From 2536fa0cd5566e665290846339d2c0f02f6b049f Mon Sep 17 00:00:00 2001
From: Dmitriy Novozhilov <dmitriy.novozhilov@jetbrains.com>
Date: Wed, 11 Dec 2019 16:16:22 +0300
Subject: [PATCH] [FIR-TEST] Add new testdata generated after changes in
 previous commit

---
 .../diagnostics/tests/Abstract.fir.kt         |  61 +++
 .../diagnostics/tests/AbstractAccessor.fir.kt |  21 +
 .../tests/AbstractInAbstractClass.fir.kt      |  45 +++
 .../diagnostics/tests/AbstractInClass.fir.kt  |  45 +++
 .../diagnostics/tests/AbstractInTrait.fir.kt  |  45 +++
 ...onymousInitializerVarAndConstructor.fir.kt |  10 +
 .../tests/AnonymousInitializers.fir.kt        |  26 ++
 .../tests/AssignToArrayElement.fir.kt         |  10 +
 .../diagnostics/tests/AutoCreatedIt.fir.kt    |  33 ++
 .../diagnostics/tests/BacktickNames.fir.kt    |  94 +++++
 .../testData/diagnostics/tests/Basic.fir.kt   |  16 +
 .../tests/BinaryCallsOnNullableValues.fir.kt  |  32 ++
 .../testData/diagnostics/tests/Bounds.fir.kt  |  43 ++
 .../diagnostics/tests/BreakContinue.fir.kt    |  96 +++++
 .../tests/BreakContinueInWhen_after.fir.kt    |  92 +++++
 .../tests/BreakContinueInWhen_before.fir.kt   |  57 +++
 .../diagnostics/tests/Builders.fir.kt         | 159 ++++++++
 .../testData/diagnostics/tests/Casts.fir.kt   |  23 ++
 .../tests/CharacterLiterals.fir.kt            |  13 +
 .../tests/CompareToWithErrorType.fir.kt       |   6 +
 .../diagnostics/tests/Constants.fir.kt        |  53 +++
 .../diagnostics/tests/Constructors.fir.kt     |  35 ++
 .../tests/ConstructorsOfPrimitives.fir.kt     |  10 +
 .../tests/CovariantOverrideType.fir.kt        |  26 ++
 ...aultValueForParameterInFunctionType.fir.kt |  20 +
 .../DefaultValuesCheckWithoutBody.fir.kt      |   9 +
 .../tests/DefaultValuesTypechecking.fir.kt    |  16 +
 .../diagnostics/tests/DeferredTypes.fir.kt    |   5 +
 ...tedGetSetPropertyDelegateConvention.fir.kt |  53 +++
 .../DeprecatedUnaryOperatorConventions.fir.kt |  33 ++
 .../diagnostics/tests/DiamondFunction.fir.kt  |   9 +
 .../tests/DiamondFunctionGeneric.fir.kt       |   9 +
 .../diagnostics/tests/DiamondProperty.fir.kt  |  11 +
 .../testData/diagnostics/tests/Dollar.fir.kt  |  12 +
 .../diagnostics/tests/EnumEntryAsType.fir.kt  |  55 +++
 .../tests/ExtensionCallInvoke.fir.kt          |   7 +
 .../tests/ExternalAccessors.fir.kt            |  19 +
 .../tests/ExternalAndAbstract.fir.kt          |   9 +
 .../tests/ForRangeConventions.fir.kt          |  93 +++++
 .../FreeFunctionCalledAsExtension.fir.kt      |  13 +
 .../tests/FunctionCalleeExpressions.fir.kt    |  84 ++++
 .../tests/FunctionParameterWithoutType.fir.kt |  11 +
 .../tests/FunctionReturnTypes.fir.kt          | 209 ++++++++++
 .../tests/GenericArgumentConsistency.fir.kt   |  43 ++
 .../GenericFunctionIsLessSpecific.fir.kt      |  10 +
 .../IdentityComparisonWithPrimitives.fir.kt   |  81 ++++
 .../testData/diagnostics/tests/IncDec.fir.kt  |  46 +++
 .../tests/IncorrectCharacterLiterals.fir.kt   |  37 ++
 .../tests/InferNullabilityInThenBlock.fir.kt  |   9 +
 .../testData/diagnostics/tests/Infix.fir.kt   |  38 ++
 .../tests/InfixModifierApplicability.fir.kt   |  27 ++
 .../tests/InvokeAndRecursiveResolve.fir.kt    |  19 +
 .../diagnostics/tests/IsExpressions.fir.kt    |  26 ++
 .../diagnostics/tests/LValueAssignment.fir.kt | 143 +++++++
 .../diagnostics/tests/LiteralAsResult.fir.kt  |   3 +
 .../LocalClassAndShortSubpackageNames.fir.kt  |  17 +
 .../tests/MultilineStringTemplates.fir.kt     |  43 ++
 .../diagnostics/tests/MultipleBounds.fir.kt   |  69 ++++
 ...medFunctionTypeParameterInSupertype.fir.kt |   9 +
 .../diagnostics/tests/Nullability.fir.kt      | 296 ++++++++++++++
 .../tests/NumberPrefixAndSuffix.fir.kt        |  54 +++
 .../tests/ObjectWithConstructor.fir.kt        |  24 ++
 .../diagnostics/tests/OperatorChecks.fir.kt   | 219 +++++++++++
 .../diagnostics/tests/Operators.fir.kt        | 114 ++++++
 .../tests/OperatorsWithWrongNames.fir.kt      |  11 +
 ...errideFunctionWithParamDefaultValue.fir.kt |  11 +
 ...enFunctionAndSpecifiedTypeParameter.fir.kt |  13 +
 .../tests/OverridenSetterVisibility.fir.kt    |  29 ++
 .../tests/OverridingVarByVal.fir.kt           |  15 +
 .../tests/PackageInExpressionPosition.fir.kt  |  26 ++
 .../tests/PackageInTypePosition.fir.kt        |   9 +
 .../diagnostics/tests/PackageQualified.fir.kt |  71 ++++
 .../tests/PrimaryConstructors.fir.kt          |  29 ++
 .../tests/PrivateFromOuterPackage.fir.kt      |  25 ++
 .../tests/PrivateSetterForOverridden.fir.kt   |  70 ++++
 .../tests/ProcessingEmptyImport.fir.kt        |   3 +
 .../ProjectionOnFunctionArgumentErrror.fir.kt |   4 +
 .../tests/ProjectionsInSupertypes.fir.kt      |   6 +
 .../diagnostics/tests/Properties.fir.kt       |  22 ++
 .../tests/PropertyInitializers.fir.kt         |   9 +
 .../tests/QualifiedExpressions.fir.kt         |  14 +
 .../diagnostics/tests/RecursiveResolve.fir.kt |  75 ++++
 .../tests/RecursiveTypeInference.fir.kt       |  43 ++
 .../diagnostics/tests/ReserveYield.fir.kt     |  71 ++++
 .../diagnostics/tests/ReserveYield2.fir.kt    |  54 +++
 .../tests/ResolveOfJavaGenerics.fir.kt        |  22 ++
 .../diagnostics/tests/ResolveToJava.fir.kt    |  58 +++
 .../testData/diagnostics/tests/Return.fir.kt  |  17 +
 .../tests/ReturnInFunctionWithoutBody.fir.kt  |   3 +
 .../diagnostics/tests/SafeCallInvoke.fir.kt   |  24 ++
 .../tests/SafeCallNonNullReceiver.fir.kt      |   6 +
 .../SafeCallNonNullReceiverReturnNull.fir.kt  |   7 +
 .../tests/SafeCallOnFakePackage.fir.kt        |  16 +
 .../tests/SafeCallOnSuperReceiver.fir.kt      |  11 +
 .../diagnostics/tests/Serializable.fir.kt     |  55 +++
 .../diagnostics/tests/SetterVisibility.fir.kt |  25 ++
 .../tests/ShiftFunctionTypes.fir.kt           |  52 +++
 .../tests/SingleUnderscoreUnsupported.fir.kt  |  27 ++
 .../tests/StarsInFunctionCalls.fir.kt         |  15 +
 .../tests/StringPrefixAndSuffix.fir.kt        |  40 ++
 .../diagnostics/tests/StringTemplates.fir.kt  |  22 ++
 .../tests/SupertypeListChecks.fir.kt          |  49 +++
 .../SyntaxErrorInTestHighlighting.fir.kt      |   5 +
 .../SyntaxErrorInTestHighlightingEof.fir.kt   |   1 +
 .../tests/TraitOverrideObjectMethods.fir.kt   |   6 +
 .../tests/TraitWithConstructor.fir.kt         |  18 +
 .../diagnostics/tests/TypeInference.fir.kt    |  19 +
 ...eMismatchOnOverrideWithSyntaxErrors.fir.kt |   9 +
 .../diagnostics/tests/Underscore.fir.kt       |  46 +++
 .../tests/UnderscoreUsageInAnnotation.fir.kt  |   6 +
 .../tests/UnderscoreUsageInCall.fir.kt        |  42 ++
 ...UnderscoreUsageInCallableRefTypeLHS.fir.kt |  11 +
 .../tests/UnderscoreUsageInType.fir.kt        |  12 +
 ...rscoreUsageInVariableAsFunctionCall.fir.kt |   6 +
 .../UnitByDefaultForFunctionTypes.fir.kt      |   3 +
 .../diagnostics/tests/UnitValue.fir.kt        |   5 +
 .../diagnostics/tests/Unresolved.fir.kt       |  32 ++
 .../tests/UnusedInDestructuring.fir.kt        |   9 +
 .../diagnostics/tests/UnusedParameters.fir.kt |  43 ++
 .../tests/UnusedParametersVersion10.fir.kt    |   3 +
 .../diagnostics/tests/UnusedVariables.fir.kt  | 133 +++++++
 ...ValAndFunOverrideCompatibilityClash.fir.kt |   9 +
 .../diagnostics/tests/VarargTypes.fir.kt      |  26 ++
 .../testData/diagnostics/tests/Varargs.fir.kt |  17 +
 .../diagnostics/tests/Variance.fir.kt         |  41 ++
 .../AmbigiousAnnotationConstructor.fir.kt     |   6 +
 .../annotations/AnnotatedConstructor.fir.kt   |   2 +
 .../AnnotatedConstructorParams.fir.kt         |  15 +
 .../AnnotatedLocalObjectFun.fir.kt            |   8 +
 .../AnnotatedLocalObjectProperty.fir.kt       |   8 +
 .../tests/annotations/AnnotatedLoop.fir.kt    |   8 +
 .../annotations/AnnotatedResultType.fir.kt    |   5 +
 .../annotations/AnnotatedTryCatch.fir.kt      |   9 +
 .../AnnotationAsDefaultParameter.fir.kt       |   5 +
 .../AnnotationForClassTypeParameter.fir.kt    |  10 +
 .../AnnotationForFunctionTypeParameter.fir.kt |  12 +
 .../annotations/AnnotationForObject.fir.kt    |   3 +
 .../annotations/AnnotationIdentifier.fir.kt   |  19 +
 .../annotations/AnnotationOnObject.fir.kt     |   6 +
 .../annotations/AnnotationsForClasses.fir.kt  |   1 +
 ...AnnotationsForPropertyTypeParameter.fir.kt |  12 +
 .../tests/annotations/BasicAnnotations.fir.kt |  10 +
 .../tests/annotations/ConstructorCall.fir.kt  |  35 ++
 .../tests/annotations/DanglingMixed.fir.kt    |  22 ++
 .../annotations/DanglingNoBrackets.fir.kt     |  13 +
 .../annotations/DanglingWithBrackets.fir.kt   |  16 +
 .../tests/annotations/Deprecated.fir.kt       |   5 +
 .../JavaAnnotationConstructors.fir.kt         |  10 +
 .../tests/annotations/MultiDeclaration.fir.kt |   9 +
 ...yRecursivelyAnnotatedGlobalFunction.fir.kt |   4 +
 .../annotations/NonAnnotationClass.fir.kt     |   3 +
 .../annotations/RecursivelyAnnotated.fir.kt   |   3 +
 ...cursivelyAnnotatedFunctionParameter.fir.kt |   3 +
 .../RecursivelyAnnotatedGlobalFunction.fir.kt |   3 +
 .../RecursivelyAnnotatedGlobalProperty.fir.kt |   3 +
 .../RecursivelyAnnotatedParameter.fir.kt      |   2 +
 .../RecursivelyAnnotatedParameterType.fir.kt  |   3 +
 ...RecursivelyAnnotatedParameterWithAt.fir.kt |   2 +
 .../RecursivelyAnnotatedProperty.fir.kt       |   5 +
 ...sivelyIncorrectlyAnnotatedParameter.fir.kt |   2 +
 ...nnotationWithExpressionTarget_after.fir.kt |  13 +
 ...notationWithExpressionTarget_before.fir.kt |  13 +
 .../UnresolvedAnnotationOnObject.fir.kt       |   9 +
 .../WrongAnnotationArgsOnObject.fir.kt        |   8 +
 ...annotatedExpressionInsideAnnotation.fir.kt |  11 +
 .../annotations/annotationInheritance.fir.kt  |   8 +
 .../annotations/annotationModifier.fir.kt     |  15 +
 ...annotationOnParameterInFunctionType.fir.kt |  29 ++
 ...notationConstructorDefaultParameter.fir.kt |  12 +
 .../booleanLocalVal.fir.kt                    |   6 +
 .../compareAndEquals.fir.kt                   |  16 +
 .../enumConst_after.fir.kt                    |  15 +
 .../enumConst_before.fir.kt                   |  15 +
 .../javaProperties.fir.kt                     |  25 ++
 .../kotlinProperties.fir.kt                   |  18 +
 .../standaloneInExpression.fir.kt             |  18 +
 .../strings.fir.kt                            |  28 ++
 .../annotationRenderingInTypes.fir.kt         |  26 ++
 .../annotationsOnLambdaAsCallArgument.fir.kt  |  19 +
 .../annotationsOnNullableTypes.fir.kt         |  44 +++
 .../annotations/atAnnotationResolve.fir.kt    |  19 +
 .../blockLevelOnTheSameLineWarning.fir.kt     |  62 +++
 .../annotations/deprecatedRepeatable.fir.kt   |  11 +
 .../annotations/extensionFunctionType.fir.kt  |  11 +
 .../forParameterAnnotationResolve.fir.kt      |  14 +
 ...onParenthesizedAnnotationsWithError.fir.kt |  70 ++++
 ...arenthesizedAnnotationsWithoutError.fir.kt |  67 ++++
 .../parenthesizedAnnotations.fir.kt           |  46 +++
 .../illegalRequireKotlinValue.fir.kt          |  38 ++
 .../illegalSinceKotlinValue.fir.kt            |  74 ++++
 .../inheritFromAnnotationClass.fir.kt         |   4 +
 .../inheritFromAnnotationClass2.fir.kt        |  25 ++
 ...invalidTypesInAnnotationConstructor.fir.kt |  76 ++++
 .../tests/annotations/javaRepeatable.fir.kt   |  19 +
 .../javaRepeatableRetention.fir.kt            |  20 +
 .../tests/annotations/javaUnrepeatable.fir.kt |   9 +
 .../tests/annotations/kt1860-negative.fir.kt  |  10 +
 .../tests/annotations/kt1860-positive.fir.kt  |  14 +
 .../kt1886annotationBody_after.fir.kt         |  31 ++
 .../kt1886annotationBody_before.fir.kt        |  31 ++
 .../annotations/missingValOnParameter.fir.kt  |   5 +
 .../nestedClassesInAnnotations.fir.kt         |  23 ++
 .../tests/annotations/noNameProperty.fir.kt   |   1 +
 .../tests/annotations/onExpression.fir.kt     |   5 +
 .../annotations/onFunctionParameter.fir.kt    |   7 +
 .../tests/annotations/onInitializer.fir.kt    |  11 +
 .../tests/annotations/onLoops.fir.kt          |  12 +
 .../annotations/onLoopsUnreachable.fir.kt     |  12 +
 .../annotations/onMultiDeclaration.fir.kt     |   7 +
 .../options/annotationAsArg.fir.kt            |  14 +
 .../options/annotationAsArgComplex.fir.kt     |  10 +
 .../annotations/options/assignment.fir.kt     |  10 +
 .../annotations/options/documented.fir.kt     |   8 +
 .../tests/annotations/options/forParam.fir.kt |  10 +
 .../options/functionExpression.fir.kt         |  12 +
 .../annotations/options/functions.fir.kt      |  40 ++
 .../annotations/options/javaDocumented.fir.kt |  20 +
 .../options/javaKotlinTargetRetention.fir.kt  |   9 +
 .../annotations/options/javaretention.fir.kt  |  35 ++
 .../options/multiDeclaration.fir.kt           |   7 +
 .../annotations/options/objectLiteral.fir.kt  |   8 +
 .../tests/annotations/options/prefix.fir.kt   |  13 +
 .../annotations/options/repeatable.fir.kt     |  31 ++
 .../annotations/options/retention.fir.kt      |   4 +
 .../annotations/options/setterParam.fir.kt    |   8 +
 .../tests/annotations/options/target.fir.kt   |   4 +
 .../options/targets/accessors.fir.kt          |  16 +
 .../options/targets/annotation.fir.kt         |  20 +
 .../options/targets/classifier.fir.kt         |  21 +
 .../options/targets/constructor.fir.kt        |  20 +
 .../annotations/options/targets/empty.fir.kt  |  21 +
 .../annotations/options/targets/expr.fir.kt   |  13 +
 .../annotations/options/targets/field.fir.kt  |  45 +++
 .../annotations/options/targets/file.fir.kt   |  23 ++
 .../options/targets/function.fir.kt           |  22 ++
 .../options/targets/funtypeargs.fir.kt        |  14 +
 .../options/targets/incorrect.fir.kt          |  21 +
 .../annotations/options/targets/init.fir.kt   |   6 +
 .../annotations/options/targets/java.fir.kt   |  82 ++++
 .../annotations/options/targets/local.fir.kt  |  20 +
 .../annotations/options/targets/nested.fir.kt |  15 +
 .../options/targets/property.fir.kt           |  21 +
 .../options/targets/returntype.fir.kt         |   9 +
 .../options/targets/suppress.fir.kt           |   5 +
 .../annotations/options/targets/type.fir.kt   |  20 +
 .../options/targets/typeParams.fir.kt         |  38 ++
 .../options/targets/typeargs.fir.kt           |  10 +
 .../options/targets/valueparam.fir.kt         |  21 +
 .../annotations/options/unrepeatable.fir.kt   |  23 ++
 .../cannotOverrideInvisibleMember.fir.kt      |  15 +
 .../rendering/conflictingOverloads.fir.kt     |  10 +
 .../differentNamesForParameter.fir.kt         |  18 +
 .../rendering/memberProjectedOut.fir.kt       |  16 +
 .../multipleInheritedDefaults.fir.kt          |  26 ++
 .../rendering/notImplementedMembers.fir.kt    |  48 +++
 .../rendering/tooManyArguments.fir.kt         |  11 +
 .../typeMismatchDueToTypeProjections.fir.kt   |  18 +
 .../rendering/typeMismatchOnOverride.fir.kt   |  26 ++
 .../typeMismatchOnOverrideJavaNullable.fir.kt |  42 ++
 .../annotations/rendering/unusedValue.fir.kt  |  12 +
 .../tests/annotations/typeAnnotations.fir.kt  |  15 +
 .../typeParameterAsAnnotation.fir.kt          |   9 +
 .../unresolvedReferenceRange.fir.kt           |   5 +
 .../DelegateAnnotations.fir.kt                |  33 ++
 .../withUseSiteTarget/FieldAnnotations.fir.kt |  36 ++
 .../withUseSiteTarget/FileAnnotations.fir.kt  |  12 +
 .../GetterAnnotations.fir.kt                  |  39 ++
 .../withUseSiteTarget/ParamAnnotations.fir.kt |  24 ++
 .../PropertyAnnotations.fir.kt                |  39 ++
 .../ReceiverAnnotations.fir.kt                |  25 ++
 .../SetterAnnotations.fir.kt                  |  38 ++
 .../SparamAnnotations.fir.kt                  |  39 ++
 ...iagnosticFileAnnotationInWrongPlace.fir.kt |  20 +
 .../diagnosticWithoutPackage.fir.kt           |   8 +
 ...cWithoutPackageWithSimpleAnnotation.fir.kt |   8 +
 .../fileAnnotationWithoutColon_after.fir.kt   |  11 +
 .../fileAnnotationWithoutColon_before.fir.kt  |  11 +
 .../withUseSiteTarget/kt23992.fir.kt          |   9 +
 .../withUseSiteTarget/kt23992_after.fir.kt    |   9 +
 .../withUseSiteTarget/kt26638.fir.kt          |  22 ++
 .../withUseSiteTarget/kt26638_after.fir.kt    |  22 ++
 ...SiteTargetOnExtensionFunction_after.fir.kt |  10 +
 ...iteTargetOnExtensionFunction_before.fir.kt |  10 +
 .../withUseSiteTarget/repeatable.fir.kt       |  59 +++
 .../wrongParamAnnotationsOnTypesError.fir.kt  |  13 +
 .../wrongParamAnnotationsOnTypes_after.fir.kt |  13 +
 ...wrongParamAnnotationsOnTypes_before.fir.kt |  13 +
 .../tests/backingField/CustomGetSet.fir.kt    |   6 +
 .../tests/backingField/CustomGetVal.fir.kt    |   4 +
 .../backingField/CustomGetValGlobal.fir.kt    |   3 +
 .../tests/backingField/CustomGetVar.fir.kt    |   4 +
 .../tests/backingField/CustomSet.fir.kt       |   4 +
 .../backingField/ExtensionProperty.fir.kt     |  17 +
 .../tests/backingField/FieldAsParam.fir.kt    |   8 +
 .../tests/backingField/FieldAsProperty.fir.kt |   9 +
 .../tests/backingField/FieldDerived.fir.kt    |  18 +
 .../backingField/FieldInInterface.fir.kt      |   4 +
 .../tests/backingField/FieldInLocal.fir.kt    |  11 +
 .../tests/backingField/FieldOnVal.fir.kt      |   2 +
 .../tests/backingField/FieldOnVar.fir.kt      |   5 +
 .../FieldReassignment_after.fir.kt            |   7 +
 .../FieldReassignment_before.fir.kt           |   7 +
 .../tests/backingField/FieldShadow.fir.kt     |   8 +
 .../backingField/InitCustomSetter.fir.kt      |  30 ++
 .../tests/backingField/InitOpenSetter.fir.kt  |  27 ++
 .../SetterWithExplicitType.fir.kt             |  26 ++
 .../backingField/kt782packageLevel.fir.kt     |  16 +
 .../tests/callableReference/bareType.fir.kt   |   8 +
 .../bound/classVsStarImportedCompanion.fir.kt |  18 +
 .../bound/classVsStarImportedObject.fir.kt    |  19 +
 .../bound/companionObject.fir.kt              |  39 ++
 .../bound/controlFlow.fir.kt                  |  22 ++
 .../callableReference/bound/dataFlow.fir.kt   |  13 +
 .../bound/expectedType.fir.kt                 |  14 +
 .../bound/expressionWithNullableType.fir.kt   |  15 +
 .../bound/functionCallWithoutArguments.fir.kt |   1 +
 .../bound/innerNested.fir.kt                  |   9 +
 .../callableReference/bound/kt12843.fir.kt    |   6 +
 .../bound/noThisInSuperCall.fir.kt            |   3 +
 .../callableReference/bound/object.fir.kt     |  11 +
 .../bound/privateToThis.fir.kt                |  24 ++
 .../referenceToStaticMethodOnInstance.fir.kt  |  14 +
 .../bound/reservedExpressionSyntax.fir.kt     |  33 ++
 .../bound/reservedExpressionSyntax2.fir.kt    |   7 +
 .../bound/reservedExpressionSyntax3.fir.kt    |  29 ++
 .../bound/syntheticExtensionOnLHS.fir.kt      |  13 +
 .../bound/valueOfTypeParameterType.fir.kt     |   3 +
 ...bleReferenceAsLastExpressionInBlock.fir.kt |  17 +
 .../callableReference/classVsPackage.fir.kt   |  24 ++
 ...nstraintFromLHSWithCorrectDirection.fir.kt |  24 ++
 .../correctInfoAfterArrayLikeCall.fir.kt      |  16 +
 .../ea81649_errorPropertyLHS.fir.kt           |  20 +
 .../tests/callableReference/emptyLhs.fir.kt   |  41 ++
 ...expectedTypeAsSubtypeOfFunctionType.fir.kt |  13 +
 .../function/abstractClassConstructors.fir.kt |  12 +
 .../ambiguityTopLevelVsTopLevel.fir.kt        |   9 +
 .../annotationClassConstructor.fir.kt         |   5 +
 .../callableRefrenceOnNestedObject.fir.kt     |   9 +
 ...lassMemberVsConstructorLikeFunction.fir.kt |  16 +
 .../function/constructorFromClass.fir.kt      |  19 +
 .../function/constructorFromCompanion.fir.kt  |  22 ++
 .../function/constructorFromExtension.fir.kt  |  14 +
 .../constructorFromExtensionInClass.fir.kt    |  23 ++
 .../function/constructorFromTopLevel.fir.kt   |  11 +
 .../constructorOfNestedClassInObject.fir.kt   |  21 +
 .../function/differentPackageClass.fir.kt     |  28 ++
 .../function/differentPackageExtension.fir.kt |  28 ++
 .../function/differentPackageTopLevel.fir.kt  |  28 ++
 .../callableReference/function/empty.fir.kt   |   6 +
 .../function/extensionFromTopLevel.fir.kt     |  23 ++
 .../extensionInClassDisallowed.fir.kt         |  20 +
 .../function/extensionOnNullable.fir.kt       |  12 +
 .../function/extensionToSupertype.fir.kt      |  19 +
 .../function/fakeOverrideType.fir.kt          |  17 +
 .../function/genericClassFromTopLevel.fir.kt  |  13 +
 .../function/importedInnerConstructor.fir.kt  |  10 +
 .../function/innerConstructorFromClass.fir.kt |  34 ++
 .../innerConstructorFromExtension.fir.kt      |  23 ++
 .../innerConstructorFromTopLevel.fir.kt       |  14 +
 .../function/javaStaticMethod.fir.kt          |  24 ++
 .../function/lhsNotAClass.fir.kt              |   9 +
 .../function/localConstructor.fir.kt          |  10 +
 ...onstructorFromExtensionInLocalClass.fir.kt |  18 +
 .../localConstructorFromLocalClass.fir.kt     |  10 +
 .../localConstructorFromLocalExtension.fir.kt |  17 +
 .../function/localNamedFun.fir.kt             |  17 +
 ...alNamedFunFromExtensionInLocalClass.fir.kt |  23 ++
 .../localNamedFunFromLocalClass.fir.kt        |  21 +
 .../localNamedFunFromLocalExtension.fir.kt    |  21 +
 .../function/longQualifiedName.fir.kt         |  18 +
 .../function/longQualifiedNameGeneric.fir.kt  |  18 +
 .../function/memberFromTopLevel.fir.kt        |  23 ++
 .../nestedConstructorFromClass.fir.kt         |  33 ++
 .../nestedConstructorFromExtension.fir.kt     |  21 +
 .../nestedConstructorFromTopLevel.fir.kt      |  13 +
 .../noAmbiguityLocalVsTopLevel.fir.kt         |   8 +
 .../noAmbiguityMemberVsExtension.fir.kt       |  15 +
 .../noAmbiguityMemberVsTopLevel.fir.kt        |  31 ++
 .../privateStaticAndPublicMember.fir.kt       |  10 +
 .../function/renameOnImport.fir.kt            |  30 ++
 .../function/topLevelFromClass.fir.kt         |  19 +
 .../function/topLevelFromExtension.fir.kt     |  19 +
 .../topLevelFromExtensionInClass.fir.kt       |  21 +
 .../function/topLevelFromTopLevel.fir.kt      |  17 +
 .../function/unresolved.fir.kt                |  24 ++
 ...WithDefaultValueAsOtherFunctionType.fir.kt |  18 +
 ...ultValueAsOtherFunctionType_enabled.fir.kt |  18 +
 .../argumentAndReturnExpectedType.fir.kt      |  37 ++
 .../generic/argumentExpectedType.fir.kt       |  12 +
 .../generic/dependOnArgumentType.fir.kt       |  30 ++
 .../generic/expectedFunctionType.fir.kt       |  24 ++
 .../generic/explicitTypeArguments.fir.kt      |  25 ++
 .../generic/genericExtensionFunction.fir.kt   |  31 ++
 .../genericFunctionsWithNullableTypes.fir.kt  |  37 ++
 .../callableReference/generic/kt10968.fir.kt  |  11 +
 .../callableReference/generic/kt11075.fir.kt  |  10 +
 .../callableReference/generic/kt12286.fir.kt  |   8 +
 .../callableReference/generic/kt7470.fir.kt   |   8 +
 .../generic/nestedCallWithOverload.fir.kt     |  22 ++
 ...ferenceFeatureForCallableReferences.fir.kt |  67 ++++
 ...ionGenericCallableWithNullableTypes.fir.kt |  23 ++
 .../resolutionWithGenericCallable.fir.kt      |  22 ++
 .../generic/specialCalls.fir.kt               |  23 ++
 .../kt15439_completeCall.fir.kt               |  11 +
 .../tests/callableReference/kt25433.fir.kt    |  17 +
 .../tests/callableReference/kt31981.fir.kt    |  23 ++
 .../tests/callableReference/kt32256.fir.kt    |  26 ++
 .../kt7430_wrongClassOnLHS.fir.kt             |  12 +
 ...sionsImportedFromObjectsUnsupported.fir.kt |  26 ++
 ...ExceptionOnRedCodeWithArrayLikeCall.fir.kt |  13 +
 .../callableReference/packageInLhs.fir.kt     |  16 +
 ...ingPriorityOfGenericArgumentsVsLess.fir.kt |   9 +
 .../abstractPropertyViaSubclasses.fir.kt      |  36 ++
 .../property/accessViaSubclass.fir.kt         |  15 +
 .../property/classFromClass.fir.kt            |  12 +
 .../property/extensionFromTopLevel.fir.kt     |  25 ++
 .../extensionPropertyOnNullable.fir.kt        |  10 +
 .../property/genericClass.fir.kt              |  16 +
 .../property/javaInstanceField.fir.kt         |  26 ++
 .../property/javaStaticFieldViaImport.fir.kt  |  28 ++
 .../callableReference/property/kt7564.fir.kt  |  12 +
 .../property/kt7945_unrelatedClass.fir.kt     |  11 +
 .../property/localVariable.fir.kt             |  15 +
 .../property/memberFromTopLevel.fir.kt        |  25 ++
 .../property/protectedVarFromClass.fir.kt     |  22 ++
 ...eturnTypeDependentOnGenericProperty.fir.kt |   8 +
 ...mePriorityForFunctionsAndProperties.fir.kt |  13 +
 .../property/syntheticProperties.fir.kt       |  19 +
 .../property/topLevelFromTopLevel.fir.kt      |  32 ++
 .../propertyOfNestedGenericClass.fir.kt       |  43 ++
 ...pplicableCallableReferenceCandidate.fir.kt |  11 +
 .../resolve/ambiguousWithVararg.fir.kt        |  16 +
 ...leCallableReferenceFromDistantScope.fir.kt |  15 +
 .../resolve/byArgType.fir.kt                  |  10 +
 .../resolve/byGenericArgType.fir.kt           |  11 +
 .../resolve/byValType.fir.kt                  |   9 +
 ...eferenceDependingOnInferredReceiver.fir.kt |  39 ++
 ...andidateDescriptorNotReflectionType.fir.kt |  14 +
 ...eOuterCallBySingleCallableReference.fir.kt |  18 +
 ...eFromReturnTypesOfCallableReference.fir.kt |  16 +
 .../resolve/constructor.fir.kt                |  12 +
 ...eagerAndPostponedCallableReferences.fir.kt |  35 ++
 ...gerResolveOfSingleCallableReference.fir.kt |  15 +
 ...lassConstructorOnOuterClassInstance.fir.kt |  13 +
 ...ctionTypeOverloadWithWrongParameter.fir.kt |  19 +
 .../callableReference/resolve/kt10036.fir.kt  |  19 +
 .../resolve/kt10036_bound.fir.kt              |  11 +
 .../callableReference/resolve/kt12338.fir.kt  |   9 +
 .../callableReference/resolve/kt12751.fir.kt  |  15 +
 .../callableReference/resolve/kt8596.fir.kt   |  25 ++
 .../callableReference/resolve/kt9601.fir.kt   |  15 +
 .../moreSpecificAmbiguousExtensions.fir.kt    |  21 +
 .../resolve/moreSpecificSimple.fir.kt         |  12 +
 ...OutersAndMultipleCallableReferences.fir.kt |  16 +
 ...ityBetweenTopLevelAndMemberProperty.fir.kt |  16 +
 .../resolve/noFakeDescriptorForObject.fir.kt  |  11 +
 .../resolve/overloads.fir.kt                  |  30 ++
 .../resolve/overloadsBound.fir.kt             |  13 +
 .../resolve/overloadsMember.fir.kt            |  16 +
 ...ponedResolveOfManyCallableReference.fir.kt |  19 +
 ...leReferencesAfterAllSimpleArguments.fir.kt |  16 +
 ...veEqualsOperatorWithAnyExpectedType.fir.kt |  11 +
 .../callableReference/resolve/valVsFun.fir.kt |  11 +
 .../callableReference/resolve/withAs.fir.kt   |  10 +
 .../resolve/withExtFun.fir.kt                 |  27 ++
 .../resolve/withGenericFun.fir.kt             |  12 +
 .../resolve/withPlaceholderTypes.fir.kt       |  28 ++
 .../resolve/withVararg.fir.kt                 |  10 +
 .../rewriteAtSliceOnGetOperator.fir.kt        |  18 +
 .../tests/callableReference/sam.fir.kt        |  31 ++
 .../subtypeArgumentFromRHSForReference.fir.kt |  27 ++
 .../suspendCallableReference.fir.kt           |  17 +
 .../callableReference/typealiases.fir.kt      |  15 +
 .../tests/callableReference/unused.fir.kt     |  23 ++
 .../whitespacesInExpression.fir.kt            |  16 +
 .../diagnostics/tests/cast/AsArray.fir.kt     |   1 +
 .../tests/cast/AsErasedError.fir.kt           |   2 +
 .../tests/cast/AsErasedFine.fir.kt            |   2 +
 .../tests/cast/AsErasedStar.fir.kt            |   3 +
 .../tests/cast/AsErasedWarning.fir.kt         |   2 +
 .../tests/cast/AsInBinaryUnary.fir.kt         |  31 ++
 .../tests/cast/AsInBlockWithReturnType.fir.kt |  53 +++
 .../tests/cast/AsInExpressionBody.fir.kt      |  12 +
 .../AsInPropertyAndPropertyAccessor.fir.kt    |  17 +
 .../diagnostics/tests/cast/AsNothing.fir.kt   |  14 +
 .../diagnostics/tests/cast/AsTypeAlias.fir.kt |  18 +
 .../tests/cast/AsWithOtherParameter.fir.kt    |  34 ++
 .../diagnostics/tests/cast/DowncastMap.fir.kt |  10 +
 .../tests/cast/ExtensionAsNonExtension.fir.kt |  10 +
 .../tests/cast/FlexibleTargetType.fir.kt      |  26 ++
 ...WithOneSubstitutedAndOneSameGeneric.fir.kt |   5 +
 ...IsErasedAllowForExactSupertypeCheck.fir.kt |   5 +
 ...wForOverridenVarianceWithProjection.fir.kt |   8 +
 ...wForSupertypeCheckWithContrvariance.fir.kt |   8 +
 ...llowForSupertypeCheckWithCovariance.fir.kt |   8 +
 ...asedAllowForTypeWithIrrelevantMixin.fir.kt |   9 +
 ...ForTypeWithTwoSameTypeSubstitutions.fir.kt |   6 +
 ...sedAllowForTypeWithoutTypeArguments.fir.kt |   5 +
 .../tests/cast/IsErasedAllowFromOut.fir.kt    |   1 +
 .../tests/cast/IsErasedAllowFromOut2.fir.kt   |   1 +
 .../cast/IsErasedAllowFromOutAtClass.fir.kt   |   1 +
 .../cast/IsErasedAllowParameterSubtype.fir.kt |   7 +
 .../IsErasedAllowSameClassParameter.fir.kt    |   3 +
 ...IsErasedAllowSameParameterParameter.fir.kt |   3 +
 ...sallowDifferentArgInvariantPosition.fir.kt |   1 +
 ...sErasedDisallowForOverridenVariance.fir.kt |   8 +
 ...rasedDisallowForTypeWithConstraints.fir.kt |   6 +
 .../tests/cast/IsErasedDisallowFromAny.fir.kt |   2 +
 .../tests/cast/IsErasedDisallowFromIn.fir.kt  |   1 +
 .../tests/cast/IsErasedDisallowFromOut.fir.kt |   2 +
 .../IsErasedDisallowFromOutAtClass.fir.kt     |   1 +
 ...peMappedToTwoParamsWithFirstInvalid.fir.kt |   8 +
 ...eMappedToTwoParamsWithSecondInvalid.fir.kt |   8 +
 .../tests/cast/IsErasedNonGeneric.fir.kt      |   3 +
 .../tests/cast/IsErasedNullableTasT.fir.kt    |   1 +
 .../tests/cast/IsErasedStar.fir.kt            |   2 +
 .../tests/cast/IsErasedTasT.fir.kt            |   1 +
 .../tests/cast/IsErasedToErrorType.fir.kt     |   1 +
 .../cast/IsErasedUpcastToNonReified.fir.kt    |  27 ++
 .../IsForTypeWithComplexUpperBound.fir.kt     |  34 ++
 .../tests/cast/IsRecursionSustainable.fir.kt  |   6 +
 .../diagnostics/tests/cast/IsTraits.fir.kt    |   4 +
 .../tests/cast/IsWithCycleUpperBounds.fir.kt  |  14 +
 .../tests/cast/NullableToNullable.fir.kt      |   7 +
 .../cast/StableTypeForUselessCast.fir.kt      |  14 +
 .../tests/cast/UselessSafeCast.fir.kt         |  23 ++
 .../cast/WhenErasedDisallowFromAny.fir.kt     |   5 +
 .../tests/cast/WhenWithExpression.fir.kt      |  11 +
 .../tests/cast/bare/AsNestedBare.fir.kt       |  10 +
 .../tests/cast/bare/AsNullable.fir.kt         |  10 +
 .../cast/bare/AsNullableNotEnough.fir.kt      |  10 +
 .../tests/cast/bare/EitherAs.fir.kt           |  18 +
 .../tests/cast/bare/EitherIs.fir.kt           |  25 ++
 .../tests/cast/bare/EitherNotIs.fir.kt        |  25 ++
 .../tests/cast/bare/EitherSafeAs.fir.kt       |  18 +
 .../tests/cast/bare/EitherWhen.fir.kt         |  19 +
 .../cast/bare/ErrorsInSubstitution.fir.kt     |   9 +
 .../tests/cast/bare/FromErrorType.fir.kt      |   8 +
 .../tests/cast/bare/NullableAs.fir.kt         |   9 +
 .../cast/bare/NullableAsNotEnough.fir.kt      |   9 +
 .../tests/cast/bare/NullableAsNullable.fir.kt |  10 +
 .../bare/NullableAsNullableNotEnough.fir.kt   |   9 +
 .../tests/cast/bare/RedundantNullable.fir.kt  |   4 +
 .../tests/cast/bare/ToErrorType.fir.kt        |   6 +
 .../tests/cast/bare/UnrelatedAs.fir.kt        |   9 +
 .../tests/cast/bare/UnrelatedColon.fir.kt     |   7 +
 .../tests/cast/bare/UnrelatedIs.fir.kt        |   4 +
 .../tests/cast/checkCastToNullableType.fir.kt |  38 ++
 .../diagnostics/tests/cast/constants.fir.kt   |  51 +++
 .../tests/cast/isErasedAnyAndStarred.fir.kt   |   3 +
 .../tests/cast/isErasedTAndStarred.fir.kt     |   3 +
 .../cast/isErasedUnrelatedAndStarred.fir.kt   |   4 +
 .../diagnostics/tests/cast/kt15161.fir.kt     |   7 +
 .../diagnostics/tests/cast/kt614.fir.kt       |   1 +
 .../neverSucceeds/CastToNotNullSuper.fir.kt   |   8 +
 .../cast/neverSucceeds/MappedDirect.fir.kt    |  33 ++
 .../cast/neverSucceeds/MappedSubtypes.fir.kt  |  21 +
 .../neverSucceeds/NoGenericsRelated.fir.kt    |  46 +++
 .../neverSucceeds/NoGenericsUnrelated.fir.kt  |  34 ++
 .../diagnostics/tests/cast/nothingAs.fir.kt   |  31 ++
 .../tests/checkArguments/SpreadVarargs.fir.kt |  96 +++++
 .../checkArguments/arrayAccessSet.fir.kt      |  35 ++
 .../arrayAccessSetTooManyArgs.fir.kt          |  11 +
 .../checkArguments/booleanExpressions.fir.kt  |   7 +
 .../kt1897_diagnostic_part.fir.kt             |  29 ++
 .../tests/checkArguments/kt1940.fir.kt        |   9 +
 .../checkArguments/overloadedFunction.fir.kt  |  17 +
 .../checkArguments/twoLambdasFunction.fir.kt  |  14 +
 .../diagnostics/tests/checkType.fir.kt        |  12 +
 .../tests/classLiteral/arrays.fir.kt          |   7 +
 .../classAndObjectLiteralType.fir.kt          |  16 +
 .../classLiteral/classLiteralType.fir.kt      |  15 +
 .../expressionWithNullableType.fir.kt         |  15 +
 .../tests/classLiteral/genericArrays.fir.kt   |  11 +
 .../tests/classLiteral/genericClasses.fir.kt  |  26 ++
 .../classLiteral/inAnnotationArguments.fir.kt |  45 +++
 .../inAnnotationArguments_noTypeParams.fir.kt |  12 +
 .../classLiteral/integerValueType.fir.kt      |  11 +
 .../tests/classLiteral/nonClassesOnLHS.fir.kt |  20 +
 .../classLiteral/qualifiedClassLiteral.fir.kt |   7 +
 .../classLiteral/simpleClassLiteral.fir.kt    |   3 +
 .../tests/classLiteral/smartCast.fir.kt       |  23 ++
 .../tests/classLiteral/typealiases.fir.kt     |  15 +
 .../tests/classLiteral/unresolvedClass.fir.kt |   2 +
 .../ClassObjectCannotAccessClassFields.fir.kt |   9 +
 .../classObjects/ClassObjectVisibility.fir.kt |  30 ++
 .../tests/classObjects/ClassObjects.fir.kt    |  43 ++
 .../InnerClassAccessThroughClassObject.fir.kt |  51 +++
 .../InnerClassAccessThroughEnum_after.fir.kt  |  50 +++
 .../InnerClassAccessThroughEnum_before.fir.kt |  50 +++
 .../classObjects/InnerClassClassObject.fir.kt |  25 ++
 .../classObjects/builtInClassObjects.fir.kt   |  43 ++
 .../classObjects/classObjectHeader.fir.kt     |   9 +
 .../classObjectInLocalClass.fir.kt            |   9 +
 .../classObjectRedeclaration.fir.kt           |  20 +
 ...anionObjectOfPrivateClassVisibility.fir.kt |  19 +
 .../importClassInClassObject.fir.kt           |  11 +
 .../classObjects/invisibleClassObjects.fir.kt |  51 +++
 .../tests/classObjects/kt3866.fir.kt          |  20 +
 .../multipleDissallowedDefaultObjects.fir.kt  |  17 +
 .../nestedClassInPrivateClassObject.fir.kt    |  15 +
 .../resolveFunctionInsideClassObject.fir.kt   |   9 +
 .../typeParametersInAnnonymousObject.fir.kt   |  39 ++
 ...eParametersInAnnonymousObject_after.fir.kt |  40 ++
 .../typeParametersInObject.fir.kt             |  21 +
 .../argumentsOfAnnotation.fir.kt              |  31 ++
 .../argumentsOfAnnotationWithKClass.fir.kt    |  31 ++
 .../basicCollectionLiterals.fir.kt            |  24 ++
 ...collectionLiteralsAsPrimitiveArrays.fir.kt |  18 +
 ...lectionLiteralsOutsideOfAnnotations.fir.kt |  22 ++
 .../collectionLiteralsWithVarargs.fir.kt      |  41 ++
 .../defaultValuesInAnnotation.fir.kt          |  26 ++
 ...aultValuesWithConstantsInAnnotation.fir.kt |  25 ++
 ...noArrayLiteralsInAnnotationsFeature.fir.kt |  19 +
 .../noCollectionLiterals.fir.kt               |  16 +
 .../resolveToFunctionFromBuiltIns.fir.kt      |  18 +
 .../afterInitialization.fir.kt                |   6 +
 .../constructorConsistency/aliencall.fir.kt   |  29 ++
 .../constructorConsistency/assignment.fir.kt  |  11 +
 .../constructorConsistency/backing.fir.kt     |  30 ++
 .../tests/constructorConsistency/basic.fir.kt |  13 +
 .../constructorConsistency/companion.fir.kt   |  19 +
 .../constructorConsistency/comparison.fir.kt  |  10 +
 .../constructorConsistency/delegate.fir.kt    |  13 +
 .../constructorConsistency/derived.fir.kt     |  11 +
 .../derivedProperty.fir.kt                    |  11 +
 .../constructorConsistency/getset.fir.kt      |  26 ++
 .../tests/constructorConsistency/init.fir.kt  |   9 +
 ...initializerWithSecondaryConstructor.fir.kt |  20 +
 .../initwithgetter.fir.kt                     |  19 +
 .../constructorConsistency/inspection.fir.kt  |  56 +++
 .../lambdaInObject.fir.kt                     |  18 +
 .../constructorConsistency/lateInit.fir.kt    |  15 +
 .../constructorConsistency/localObject.fir.kt |  19 +
 .../multipleAreNull.fir.kt                    |  24 ++
 .../constructorConsistency/nobacking.fir.kt   |  12 +
 .../tests/constructorConsistency/open.fir.kt  |  34 ++
 .../openProperty.fir.kt                       |  14 +
 .../tests/constructorConsistency/outer.fir.kt |  11 +
 .../constructorConsistency/property.fir.kt    |   5 +
 .../propertyAccess.fir.kt                     |   7 +
 .../twoSecondaryConstructors.fir.kt           |  12 +
 .../UninitializedOrReassignedVariables.fir.kt | 349 ++++++++++++++++
 .../assignedInFinally.fir.kt                  |  10 +
 .../assignmentInLocalsInConstructor.fir.kt    |  67 ++++
 .../backingFieldInsideGetter_after.fir.kt     |  23 ++
 .../backingFieldInsideGetter_before.fir.kt    |  23 ++
 .../breakContinueInTryFinally.fir.kt          |  24 ++
 .../breakInsideLocal.fir.kt                   |  86 ++++
 .../breakOrContinueInLoopCondition.fir.kt     |  34 ++
 .../checkInnerLocalDeclarations.fir.kt        |  12 +
 .../checkPropertyAccessor.fir.kt              |  38 ++
 .../constructorPropertyInterdependence.fir.kt |   8 +
 .../deadCode/commasAndWhitespaces.fir.kt      |  12 +
 .../deadCode/commentsInDeadCode.fir.kt        |  22 ++
 .../deadCode/deadCallInInvokeCall.fir.kt      |  11 +
 .../deadCode/deadCallInReceiver.fir.kt        |  11 +
 .../deadCode/deadCodeDifferentExamples.fir.kt | 168 ++++++++
 .../deadCodeFromDifferentSources.fir.kt       |  23 ++
 .../deadCode/deadCodeInArrayAccess.fir.kt     |  40 ++
 .../deadCode/deadCodeInAssignment.fir.kt      |  18 +
 .../deadCodeInBinaryExpressions.fir.kt        |  39 ++
 .../deadCode/deadCodeInCalls.fir.kt           |  13 +
 .../deadCode/deadCodeInDeadCode.fir.kt        |  24 ++
 .../deadCode/deadCodeInIf.fir.kt              |  12 +
 .../deadCodeInInnerExpressions.fir.kt         |  13 +
 .../deadCodeInLocalDeclarations.fir.kt        |  36 ++
 .../deadCode/deadCodeInLoops.fir.kt           |  21 +
 .../deadCode/deadCodeInReturn.fir.kt          |   5 +
 .../deadCode/deadCodeInUnaryExpr.fir.kt       |  15 +
 .../deadCode/deadCodeInWhileFromBreak.fir.kt  |  55 +++
 .../deadCode/expressionInUnitLiteral.fir.kt   |   8 +
 .../deadCode/kt2585_1.fir.kt                  |  12 +
 .../deadCode/kt2585_2.fir.kt                  |  23 ++
 .../deadCode/kt2585_3.fir.kt                  |   9 +
 .../deadCode/kt3162tryAsInitializer.fir.kt    |  12 +
 .../deadCode/kt5200DeadCodeInLambdas.fir.kt   |  25 ++
 .../deadCode/returnInDeadLambda.fir.kt        |  11 +
 .../ReturnFromFunctionInObject.fir.kt         |  13 +
 .../kt3444_ReturnFromLocalFunctions.fir.kt    |  17 +
 .../definiteReturn/kt4034.fir.kt              |  11 +
 .../definiteReturn/simpleClass.fir.kt         |  19 +
 .../definiteReturnInWhen.fir.kt               |   6 +
 .../delegatedPropertyEarlyAccess.fir.kt       |  32 ++
 .../doWhileAssignment.fir.kt                  |  23 ++
 .../doWhileNotDefined.fir.kt                  |   6 +
 .../elvisNotProcessed.fir.kt                  |  39 ++
 .../enumCompanionInterdependence.fir.kt       |  55 +++
 .../enumInterdependence.fir.kt                |  35 ++
 .../fieldAsClassDelegate.fir.kt               |  37 ++
 .../controlFlowAnalysis/infiniteLoops.fir.kt  |  55 +++
 .../initializationInLambda.fir.kt             |  77 ++++
 .../initializationInLocalClass.fir.kt         |  90 +++++
 .../initializationInLocalFun.fir.kt           |   8 +
 ...izationInLocalViaExplicitThis_after.fir.kt |  18 +
 ...zationInLocalViaExplicitThis_before.fir.kt |  18 +
 .../tests/controlFlowAnalysis/kt1001.fir.kt   |  34 ++
 .../tests/controlFlowAnalysis/kt1027.fir.kt   |  48 +++
 .../tests/controlFlowAnalysis/kt1066.fir.kt   |  34 ++
 .../tests/controlFlowAnalysis/kt10805.fir.kt  |  13 +
 .../tests/controlFlowAnalysis/kt10823.fir.kt  |  33 ++
 .../tests/controlFlowAnalysis/kt1156.fir.kt   |   7 +
 .../controlFlowAnalysis/kt1185enums.fir.kt    |  47 +++
 .../tests/controlFlowAnalysis/kt1189.fir.kt   |  38 ++
 .../tests/controlFlowAnalysis/kt1191.fir.kt   |  21 +
 .../controlFlowAnalysis/kt1219.1301.fir.kt    |  25 ++
 .../tests/controlFlowAnalysis/kt1571.fir.kt   |  42 ++
 .../tests/controlFlowAnalysis/kt1977.fir.kt   |  51 +++
 .../controlFlowAnalysis/kt2166_kt2103.fir.kt  |  17 +
 .../tests/controlFlowAnalysis/kt2226.fir.kt   |  15 +
 .../tests/controlFlowAnalysis/kt2330.fir.kt   |  53 +++
 .../tests/controlFlowAnalysis/kt2334.fir.kt   |   5 +
 .../tests/controlFlowAnalysis/kt2369.fir.kt   |  13 +
 .../tests/controlFlowAnalysis/kt2845.fir.kt   |  18 +
 .../tests/controlFlowAnalysis/kt2960.fir.kt   |  36 ++
 .../tests/controlFlowAnalysis/kt2972.fir.kt   |  28 ++
 .../tests/controlFlowAnalysis/kt3444.fir.kt   |  13 +
 .../tests/controlFlowAnalysis/kt3501.fir.kt   |   9 +
 .../tests/controlFlowAnalysis/kt4126.fir.kt   |   3 +
 .../tests/controlFlowAnalysis/kt4405.fir.kt   |  30 ++
 .../tests/controlFlowAnalysis/kt510.fir.kt    |  18 +
 .../tests/controlFlowAnalysis/kt607.fir.kt    |  18 +
 .../tests/controlFlowAnalysis/kt609.fir.kt    |  20 +
 .../tests/controlFlowAnalysis/kt610.fir.kt    |  10 +
 .../tests/controlFlowAnalysis/kt6788.fir.kt   |  10 +
 .../tests/controlFlowAnalysis/kt776.fir.kt    |  38 ++
 .../tests/controlFlowAnalysis/kt843.fir.kt    |   8 +
 .../tests/controlFlowAnalysis/kt897.fir.kt    |  20 +
 .../controlFlowAnalysis/localClasses.fir.kt   |  26 ++
 .../localObjectInConstructor.fir.kt           |  87 ++++
 .../mainWithWarningOnUnusedParam.fir.kt       |   5 +
 .../mainWithoutWarningOnUnusedParam.fir.kt    |   5 +
 .../nestedTryFinally.fir.kt                   |  24 ++
 .../nonLocalReturnUnreachable.fir.kt          |  26 ++
 .../nonLocalReturnWithFinally.fir.kt          |  10 +
 .../controlFlowAnalysis/privateSetter.fir.kt  |  17 +
 .../propertiesInitWithOtherInstance.fir.kt    |  12 +
 ...ropertiesInitWithOtherInstanceInner.fir.kt |  21 +
 ...rtiesInitWithOtherInstanceThisLabel.fir.kt |  12 +
 .../propertiesOrderInPackage.fir.kt           |   4 +
 .../reassignmentInTryCatch.fir.kt             | 102 +++++
 .../reassignmentInTryCatchWithJumps.fir.kt    |  55 +++
 .../referenceToPropertyInitializer.fir.kt     |  32 ++
 ...eatUnitializedErrorOnlyForLocalVars.fir.kt |  15 +
 .../scopeOfAnonymousInitializer.fir.kt        |   5 +
 .../controlFlowAnalysis/throwInLambda.fir.kt  |  13 +
 .../tryWithAssignmentUsedInCatch.fir.kt       |  36 ++
 .../uninitializedInLocalDeclarations.fir.kt   |  50 +++
 .../controlFlowAnalysis/unmappedArgs.fir.kt   |   5 +
 .../lateinitRecursiveInLambda.fir.kt          |   6 +
 .../lateinitWithConstructor.fir.kt            |   9 +
 .../lateinitWithErroneousDelegation.fir.kt    |  11 +
 .../lateinitWithInit.fir.kt                   |   7 +
 .../lateinitWithMultipleConstructors.fir.kt   |  13 +
 ...thMultipleConstructorsAndDelegation.fir.kt |  15 +
 .../lateinitWithPlusAssign.fir.kt             |   8 +
 ...ithPrimaryConstructorAndConstructor.fir.kt |   9 +
 .../unnecessaryLateinit/normalLateinit.fir.kt |   7 +
 .../normalLateinitWithTwoConstructors.fir.kt  |   9 +
 .../secondaryConstructorDelegateItself.fir.kt |  13 +
 .../secondaryConstructorDelegateLoop.fir.kt   |  18 +
 .../unresolvedReference.fir.kt                |  49 +++
 .../unusedInAnonymous.fir.kt                  |   9 +
 .../useUninitializedInLambda.fir.kt           |   6 +
 .../varInitializationInIfInCycle.fir.kt       |  15 +
 ...LoopWithExtensionIteratorOnNullable.fir.kt |  22 ++
 .../controlStructures/ForWithoutBraces.fir.kt |   8 +
 ...ForbidStatementAsDirectFunctionBody.fir.kt |  11 +
 .../controlStructures/catchGenerics.fir.kt    |  26 ++
 .../catchInnerClassesOfGenerics.fir.kt        |  41 ++
 ...hInnerClassesOfGenerics_deprecation.fir.kt |  41 ++
 .../controlStructures/catchWithDefault.fir.kt |   3 +
 ...LocalClassesCapturingTypeParameters.fir.kt |  27 ++
 .../commonSupertypeOfT.fir.kt                 |  30 ++
 ...ueAndBreakLabelWithSameFunctionName.fir.kt |  53 +++
 .../tests/controlStructures/emptyIf.fir.kt    |  16 +
 .../forLoopWithNullableRange.fir.kt           |  16 +
 .../forWithNullableIterator.fir.kt            |  12 +
 .../ifElseIntersection.fir.kt                 |  55 +++
 .../ifInResultOfLambda.fir.kt                 |   8 +
 .../ifToAnyDiscriminatingUsages.fir.kt        |  62 +++
 .../ifWhenToAnyComplexExpressions.fir.kt      |  31 ++
 .../ifWhenWithoutElse.fir.kt                  |  86 ++++
 .../improperElseInExpression.fir.kt           |  34 ++
 .../jumpAcrossFunctionBoundary.fir.kt         |  17 +
 .../tests/controlStructures/kt10322.fir.kt    |  10 +
 .../tests/controlStructures/kt10706.fir.kt    |  10 +
 .../tests/controlStructures/kt10717.fir.kt    |  47 +++
 .../tests/controlStructures/kt1075.fir.kt     |  12 +
 .../tests/controlStructures/kt30406.fir.kt    |  16 +
 .../tests/controlStructures/kt4310.fir.kt     |  12 +
 .../tests/controlStructures/kt657.fir.kt      |  20 +
 ...0.fir.kt351.fir.kt735_StatementType.fir.kt | 163 ++++++++
 .../tests/controlStructures/kt786.fir.kt      |  26 ++
 .../tests/controlStructures/kt799.fir.kt      |  25 ++
 .../lambdasInExclExclAndElvis.fir.kt          |  16 +
 ...localReturnInsidePropertyAccessor.fir.fail |   2 +-
 .../localReturnInsidePropertyAccessor.fir.kt  |  20 +
 .../notAFunctionLabel_after.fir.kt            |  62 +++
 .../notAFunctionLabel_before.fir.kt           |  62 +++
 .../controlStructures/redundantLabel.fir.kt   |  39 ++
 .../specialConstructsAndPlatformTypes.fir.kt  |  40 ++
 ...lConstructsWithNullableExpectedType.fir.kt |  20 +
 .../controlStructures/tryReturnType.fir.kt    |  28 ++
 .../typeInferenceForExclExcl.fir.kt           |  21 +
 .../valVarCatchParameter.fir.kt               |  13 +
 .../valVarLoopParameter.fir.kt                |  32 ++
 .../when.fir.kt234.fir.kt973.fir.kt           |  41 ++
 .../whenInResultOfLambda.fir.kt               |  17 +
 .../whenToAnyDiscriminatingUsages.fir.kt      |  83 ++++
 .../invokeOutideSuspend.fir.kt                |   8 +
 .../callableReference/outsideSuspend.fir.kt   |  11 +
 .../classIndirectlyInheritsNested.fir.kt      |   4 +
 .../classInheritsNested.fir.kt                |   3 +
 ...mmonSupertypeForCyclicAndUsualTypes.fir.kt |   8 +
 .../commonSupertypeForCyclicTypes.fir.kt      |   8 +
 .../cyclicHierarchy/cyclicHierarchy.fir.kt    |  30 ++
 .../cyclicHierarchy/javaJavaCycle.fir.kt      |  28 ++
 .../cyclicHierarchy/javaJavaNested.fir.kt     |  24 ++
 .../javaKotlinJavaCycle.fir.kt                |  17 +
 .../cyclicHierarchy/kotlinJavaCycle.fir.kt    |  11 +
 .../kotlinJavaKotlinCycle.fir.kt              |  17 +
 .../kotlinJavaNestedCycle.fir.kt              |  21 +
 .../tests/cyclicHierarchy/kt303.fir.kt        |  12 +
 .../nestedClassInSuperClassParameter.fir.kt   |   5 +
 .../objectInheritsNested.fir.kt               |  22 ++
 .../twoClassesWithNestedCycle.fir.kt          |   6 +
 .../everythingInOneScope_after.fir.kt         |  15 +
 .../everythingInOneScope_before.fir.kt        |  15 +
 .../withCompanion/noMembers_after.fir.kt      |  15 +
 .../withCompanion/noMembers_before.fir.kt     |  15 +
 .../withCompanion/onlyInterfaces_after.fir.kt |  18 +
 .../onlyInterfaces_before.fir.kt              |  18 +
 .../withCompanion/typeIsLowEnough.fir.kt      |  20 +
 .../withIrrelevantInterface_after.fir.kt      |  20 +
 .../withIrrelevantInterface_before.fir.kt     |  20 +
 .../withCompanion/withMembers_after.fir.kt    |  58 +++
 .../withCompanion/withMembers_before.fir.kt   |  64 +++
 .../withCompanion/withoutTypeReference.fir.kt |  17 +
 .../componentNamedComponent1.fir.kt           |   6 +
 .../conflictingCopyOverloads.fir.kt           |   6 +
 .../dataClasses/conflictingOverloads.fir.kt   |   4 +
 .../dataClasses/copyOfPrivateClass.fir.kt     |   3 +
 ...sExplicitlyOverridingCopyNoDefaults.fir.kt |   9 +
 ...xplicitlyOverridingCopyWithDefaults.fir.kt |   9 +
 .../tests/dataClasses/dataClassNoName.fir.kt  |   9 +
 .../dataClassNotOverridingCopy.fir.kt         |   9 +
 .../dataClassOverridingCopy_lv12.fir.kt       |   7 +
 .../dataClassOverridingCopy_lv13.fir.kt       |   7 +
 .../dataClasses/dataClassVarargParam.fir.kt   |   3 +
 .../tests/dataClasses/dataInheritance.fir.kt  |  13 +
 .../tests/dataClasses/dataObject.fir.kt       |   1 +
 .../tests/dataClasses/emptyConstructor.fir.kt |   6 +
 .../errorTypesInDataClasses.fir.kt            |  16 +
 .../extensionComponentsOnNullable.fir.kt      |  22 ++
 .../finalMembersInBaseClass.fir.kt            |  16 +
 .../implementMethodsFromInterface.fir.kt      |  25 ++
 .../implementTraitWhichHasComponent1.fir.kt   |   5 +
 ...plementTraitWhichHasFinalComponent1.fir.kt |   5 +
 .../tests/dataClasses/innerDataClass.fir.kt   |   3 +
 .../dataClasses/innerOuterDataClass.fir.kt    |   1 +
 .../tests/dataClasses/multiDeclaration.fir.kt |   9 +
 .../dataClasses/multiDeclarationFor.fir.kt    |  10 +
 .../tests/dataClasses/noConstructor.fir.kt    |   6 +
 .../tests/dataClasses/notADataClass.fir.kt    |   6 +
 .../tests/dataClasses/oneValParam.fir.kt      |   8 +
 .../dataClasses/repeatedProperties.fir.kt     |   9 +
 .../tests/dataClasses/sealedDataClass.fir.kt  |   4 +
 .../tests/dataClasses/strange.fir.kt          |  10 +
 .../tests/dataClasses/twoValParams.fir.kt     |   8 +
 .../tests/dataClasses/twoVarParams.fir.kt     |   8 +
 .../tests/dataFlow/CalleeExpression.fir.kt    |   7 +
 .../diagnostics/tests/dataFlow/EmptyIf.fir.kt |  24 ++
 .../tests/dataFlow/IsExpression.fir.kt        |   6 +
 .../tests/dataFlow/WhenSubject.fir.kt         |  10 +
 .../dataFlow/assignment/assignToNewVal.fir.kt |  10 +
 .../tests/dataFlow/assignment/kt6118.fir.kt   |  16 +
 .../assignment/uninitializedValIsCheck.fir.kt |  15 +
 .../uninitializedValNullability.fir.kt        |  15 +
 .../tests/dataFlow/assignment/when.fir.kt     |  12 +
 .../dataFlow/local/LocalClassBase.fir.kt      |  10 +
 .../local/LocalClassDefaultParameters.fir.kt  |   8 +
 .../LocalClassDelegatedProperties.fir.kt      |  17 +
 .../local/LocalClassDelegation.fir.kt         |  11 +
 .../dataFlow/local/LocalClassFunctions.fir.kt |  18 +
 .../LocalClassInMemberOfLocalClass.fir.kt     |  15 +
 .../local/LocalClassInitializer.fir.kt        |  16 +
 .../dataFlow/local/LocalClassProperty.fir.kt  |  12 +
 .../tests/dataFlow/local/LocalObject.fir.kt   |   9 +
 .../local/LocalObjectDelegation.fir.kt        |  15 +
 .../dataFlow/local/NestedLocalClass.fir.kt    |  11 +
 .../tests/dataFlow/local/kt2835.fir.kt        |   8 +
 .../tests/dataFlowInfoTraversal/AndOr.fir.kt  |  13 +
 .../dataFlowInfoTraversal/ArrayAccess.fir.kt  |  13 +
 .../ArrayExpression.fir.kt                    |   8 +
 .../ArrayGetSetConvention.fir.kt              |  28 ++
 .../dataFlowInfoTraversal/ArrayIndices.fir.kt |  11 +
 .../dataFlowInfoTraversal/Assignment.fir.kt   |  17 +
 .../AssignmentInInitializer.fir.kt            |  21 +
 .../AssignmentOperation.fir.kt                |  17 +
 .../AssignmentToArrayElement.fir.kt           |  12 +
 .../BinaryExpression.fir.kt                   |  11 +
 .../BinaryExpressionBooleanOperations.fir.kt  |  25 ++
 ...BinaryExpressionCompareToConvention.fir.kt |  18 +
 .../BinaryExpressionContainsConvention.fir.kt |   7 +
 .../BinaryExpressionElvis.fir.kt              |  16 +
 .../BinaryExpressionEqualsConvention.fir.kt   |  16 +
 .../BinaryExpressionIdentifier.fir.kt         |  15 +
 .../BinaryExpressionPlusConvention.fir.kt     |  18 +
 .../dataFlowInfoTraversal/Condition.fir.kt    |   7 +
 .../ContinueOuterLoop.fir.kt                  |  34 ++
 .../tests/dataFlowInfoTraversal/DeepIf.fir.kt |  31 ++
 .../dataFlowInfoTraversal/DoWhile.fir.kt      |  16 +
 .../DoWhileCondition.fir.kt                   |  20 +
 .../tests/dataFlowInfoTraversal/Elvis.fir.kt  |   9 +
 .../dataFlowInfoTraversal/ExclExcl.fir.kt     |  24 ++
 .../tests/dataFlowInfoTraversal/For.fir.kt    |  22 ++
 .../dataFlowInfoTraversal/ForLoopRange.fir.kt |   8 +
 .../FunctionLiteral.fir.kt                    |   9 +
 .../dataFlowInfoTraversal/IfStatement.fir.kt  |  31 ++
 .../dataFlowInfoTraversal/IfThenElse.fir.kt   |  30 ++
 .../IfThenElseBothInvalid.fir.kt              |  16 +
 .../dataFlowInfoTraversal/IsExpression.fir.kt |   8 +
 .../dataFlowInfoTraversal/ManyIfs.fir.kt      |  32 ++
 .../MultiDeclaration.fir.kt                   |   9 +
 .../ObjectExpression.fir.kt                   |  12 +
 .../QualifiedExpression.fir.kt                |  13 +
 .../tests/dataFlowInfoTraversal/Return.fir.kt |  18 +
 .../StringTemplate.fir.kt                     |   8 +
 .../dataFlowInfoTraversal/ThisSuper.fir.kt    |  21 +
 .../tests/dataFlowInfoTraversal/Throw.fir.kt  |   9 +
 .../dataFlowInfoTraversal/TryCatch.fir.kt     |  15 +
 .../dataFlowInfoTraversal/TryFinally.fir.kt   |  21 +
 .../UnaryExpression.fir.kt                    |  14 +
 .../tests/dataFlowInfoTraversal/When.fir.kt   |  18 +
 .../dataFlowInfoTraversal/WhenEntryAs.fir.kt  |  26 ++
 .../dataFlowInfoTraversal/WhenEntryIs.fir.kt  |  26 ++
 .../tests/dataFlowInfoTraversal/WhenIn.fir.kt |  15 +
 .../dataFlowInfoTraversal/WhenSubject.fir.kt  |   8 +
 .../tests/dataFlowInfoTraversal/While.fir.kt  |  22 ++
 .../WhileCondition.fir.kt                     |  26 ++
 .../kt4332WhenBranches.fir.kt                 |   9 +
 .../kt5155WhenBranches.fir.kt                 |  11 +
 .../kt5182WhenBranches.fir.kt                 |  13 +
 .../smartcasts/SmartcastAmbiguitites.fir.kt   |  16 +
 .../SmartcastsForStableIdentifiers.fir.kt     |  86 ++++
 ...ComponentFunctionReturnTypeMismatch.fir.kt |   9 +
 .../ConflictingAndRedundantProjections.fir.kt |  20 +
 .../DataFlowInMultiDeclInFor.fir.kt           |  15 +
 .../DataFlowInfoInMultiDecl.fir.kt            |  14 +
 .../FunctionWithMissingNames.fir.kt           |  26 ++
 .../LocalVariableWithNoTypeInformation.fir.kt |   3 +
 .../MultiDeclarationErrors.fir.kt             |  21 +
 .../RedeclarationsInMultiDecl.fir.kt          |  15 +
 .../ScalaLikeNamedFun.fir.kt                  |  36 ++
 ...OnFunctionAndPropertyTypeParameters.fir.kt |  17 +
 .../ambiguousObjectExpressionType.fir.kt      | 120 ++++++
 ...anonymousFunAsLastExpressionInBlock.fir.kt |  43 ++
 ...ymousFunUnusedLastExpressionInBlock.fir.kt |  21 +
 .../DoubleDeclForLoop.fir.kt                  |  14 +
 .../FolLoopTypeComponentTypeMismatch.fir.kt   |  15 +
 .../ForLoopComponentFunctionAmbiguity.fir.kt  |  15 +
 .../ForLoopComponentFunctionMissing.fir.kt    |  13 +
 .../ForLoopMissingLoopParameter.fir.kt        |  15 +
 .../ForLoopWithExtensions.fir.kt              |  14 +
 .../ForWithExplicitTypes.fir.kt               |  14 +
 .../RedeclarationInForLoop.fir.kt             |  14 +
 .../SingleDeclForLoop.fir.kt                  |  13 +
 ...turingDeclarationAssignedUnresolved.fir.kt |  11 +
 ...turingDeclarationMissingInitializer.fir.kt |  11 +
 .../destructuringDeclarations/kt2829.fir.kt   |  16 +
 ...lastDestructuringDeclarationInBlock.fir.kt |  30 ++
 .../underscore.fir.kt                         |  51 +++
 .../CasesWithOneTypeParameter.fir.kt          |  17 +
 .../CasesWithTwoTypeParameters.fir.kt         |  12 +
 .../JavaSuperType.fir.kt                      |   5 +
 .../illegalModifiersOnClass.fir.kt            |  19 +
 .../kClassInSignature.fir.kt                  |  23 ++
 .../tests/declarationChecks/kt1141.fir.kt     |  21 +
 .../tests/declarationChecks/kt1193.fir.kt     |  13 +
 .../tests/declarationChecks/kt2096.fir.kt     |   7 +
 .../tests/declarationChecks/kt2142.fir.kt     |   8 +
 .../tests/declarationChecks/kt2397.fir.kt     |  17 +
 .../kt2631_MultipleDeclaration.fir.kt         |  27 ++
 .../kt2643MultiDeclInControlFlow.fir.kt       |  27 ++
 .../tests/declarationChecks/kt559.fir.kt      |  30 ++
 .../localDeclarationModifiers.fir.kt          |  12 +
 .../localFunctionNoInheritVisibility.fir.kt   |  16 +
 ...ocalVariablesWithTypeParameters_1_3.fir.kt |  19 +
 ...ocalVariablesWithTypeParameters_1_4.fir.kt |  19 +
 .../mulitpleVarargParameters.fir.kt           |  35 ++
 .../namedFunAsLastExpressionInBlock.fir.kt    |  75 ++++
 .../JavaWithKotlin.fir.kt                     |  14 +
 .../JavaWithKotlin2.fir.kt                    |  16 +
 .../PureKotlin.fir.kt                         |  28 ++
 .../packageDeclarationModifiers.fir.kt        |  12 +
 ...ertyInPackageHasNoInheritVisibility.fir.kt |  10 +
 .../declarationChecks/sealedOnMembers.fir.kt  |  18 +
 .../unambiguousObjectExpressionType.fir.kt    | 175 +++++++++
 .../valVarFunctionParameter.fir.kt            |  12 +
 .../tests/defaultArguments/kt5232.fir.kt      |  11 +
 .../tests/defaultArguments/superCall.fir.kt   |  28 ++
 .../absentErrorAboutInitializer.fir.kt        |  11 +
 .../absentErrorAboutType.fir.kt               |  11 +
 .../abstractDelegatedProperty.fir.kt          |  13 +
 .../delegatedProperty/backingField.fir.kt     |  15 +
 .../delegatedProperty/defaultGetter.fir.kt    |  12 +
 .../delegatedProperty/defaultSetter.fir.kt    |  14 +
 .../delegatedPropertyOverridedInTrait.fir.kt  |  21 +
 ...ropertyOverridedInTraitTypeMismatch.fir.kt |  21 +
 .../disallowImplInTypeParameter.fir.kt        |   7 +
 .../delegatedProperty/genericGetter.fir.kt    |  11 +
 .../getterWithSubtype.fir.kt                  |  15 +
 .../tests/delegatedProperty/inTrait.fir.kt    |  13 +
 .../incompleteTypeInference.fir.kt            |  17 +
 ...erenceArgumentInDelegatedExpression.fir.kt |  17 +
 .../delegateExpressionAsLambda.fir.kt         |  22 ++
 .../differentDelegatedExpressions.fir.kt      |  53 +++
 .../inference/extensionGet.fir.kt             |  35 ++
 .../inference/extensionProperty.fir.kt        |  22 ++
 .../genericMethodInGenericClass.fir.kt        |  28 ++
 .../inference/genericMethods.fir.kt           |  27 ++
 .../labeledDelegatedExpression.fir.kt         |  11 +
 .../inference/manyIncompleteCandidates.fir.kt |  26 ++
 .../noErrorsForImplicitConstraints.fir.kt     |  45 +++
 ...oExpectedTypeForSupertypeConstraint.fir.kt |  18 +
 ...ultTypeOfLambdaForConventionMethods.fir.kt |  17 +
 ...peOfLazyDelegatedPropertyWithObject.fir.kt |  29 ++
 .../useCompleterWithoutExpectedType.fir.kt    |  15 +
 .../inference/useExpectedType.fir.kt          |  76 ++++
 .../inference/useExpectedTypeForVal.fir.kt    |  64 +++
 .../tests/delegatedProperty/kt4640.fir.kt     |  11 +
 .../delegatedProperty/localVariable.fir.kt    |  15 +
 .../localWithSmartCast.fir.kt                 |  15 +
 .../delegatedProperty/missedGetter.fir.kt     |   3 +
 .../delegatedProperty/missedSetter.fir.kt     |  11 +
 .../nonDefaultAccessors.fir.kt                |  12 +
 .../propertyDefferedType.fir.kt               |  12 +
 .../commonCaseForInference.fir.kt             |  14 +
 .../genericProvideDelegate.fir.kt             |  13 +
 .../provideDelegate/hostAndReceiver1.fir.kt   |   9 +
 .../provideDelegate/hostAndReceiver2.fir.kt   |  14 +
 .../provideDelegate/hostAndReceiver3.fir.kt   |  12 +
 .../inferenceFromReceiver1.fir.kt             |  15 +
 .../inferenceFromReceiver2.fir.kt             |  14 +
 .../localDelegatedProperty.fir.kt             |  11 +
 ...noOperatorModifierOnProvideDelegate.fir.kt |  18 +
 ...esolutionForSeveralProvideDelegates.fir.kt |  19 +
 .../provideDelegateOperatorDeclaration.fir.kt |  32 ++
 .../provideDelegate/setValue.fir.kt           |  17 +
 .../simpleProvideDelegate.fir.kt              |  10 +
 .../unsupportedOperatorProvideDelegate.fir.kt |  15 +
 .../delegatedProperty/recursiveType.fir.kt    |  18 +
 .../delegatedProperty/redundantGetter.fir.kt  |  12 +
 .../delegatedProperty/redundantSetter.fir.kt  |  15 +
 .../setterThisTypeMismatch.fir.kt             |  18 +
 .../setterWithSupertype.fir.kt                |  16 +
 .../delegatedProperty/severalReceivers.fir.kt |  13 +
 .../delegatedProperty/thisInDelegate.fir.kt   |  15 +
 .../delegatedProperty/thisOfAnyType.fir.kt    |  16 +
 .../thisOfNothingNullableType.fir.kt          |  18 +
 .../thisOfNothingType.fir.kt                  |  18 +
 .../delegatedProperty/twoGetMethods.fir.kt    |  17 +
 .../typeMismatchForGetReturnType.fir.kt       |  12 +
 .../typeMismatchForGetWithGeneric.fir.kt      |  23 ++
 .../typeMismatchForSetParameter.fir.kt        |  16 +
 .../typeMismatchForThisGetParameter.fir.kt    |  18 +
 .../wrongCountOfParametersInGet.fir.kt        |  15 +
 .../wrongCountOfParametersInSet.fir.kt        |  17 +
 .../wrongSetterReturnType.fir.kt              |  15 +
 .../delegation/DelegationAndOverriding.fir.kt |  38 ++
 .../delegation/DelegationExpectedType.fir.kt  |  26 ++
 .../delegation/DelegationNotTotrait.fir.kt    |  15 +
 .../delegation/DelegationToJavaIface.fir.kt   |   4 +
 .../Delegation_ClashingFunctions.fir.kt       |  18 +
 .../delegation/Delegation_Hierarchy.fir.kt    |  12 +
 .../Delegation_MultipleDelegates.fir.kt       |  19 +
 ...Delegation_ScopeInitializationOrder.fir.kt |  10 +
 .../clashes/finalMemberOverridden.fir.kt      |  56 +++
 .../clashes/propertyTypeMismatch.fir.kt       |  57 +++
 .../clashes/returnTypeMismatch.fir.kt         |  59 +++
 .../clashes/varOverriddenByVal.fir.kt         |  29 ++
 .../covariantOverrides/fromClass.fir.kt       |  19 +
 .../covariantOverrides/irrelevant.fir.kt      |  19 +
 .../covariantOverrides/kt13952.fir.kt         |  17 +
 .../covariantOverrides/simple.fir.kt          |  19 +
 .../tests/delegation/kt8154.fir.kt            |  11 +
 .../abstractOverride.fir.kt                   |  18 +
 .../delegationToSubType.fir.kt                |  19 +
 .../delegationToSubTypeProperty.fir.kt        |  20 +
 .../delegationToSubTypeWithOverride.fir.kt    |  19 +
 ...gationToSubTypeWithOverrideProperty.fir.kt |  26 ++
 .../diamond.fir.kt                            |  43 ++
 .../explicitOverride.fir.kt                   |  18 +
 .../fakeOverrideInTheMiddle.fir.kt            |  13 +
 .../generic.fir.kt                            |  14 +
 .../sameDelegationInHierarchy.fir.kt          |  16 +
 .../sameDelegationInHierarchy2.fir.kt         |  21 +
 .../severalDelegates.fir.kt                   |  28 ++
 .../simple.fir.kt                             |  19 +
 .../simpleNoOverride.fir.kt                   |  15 +
 .../simpleProp.fir.kt                         |  17 +
 .../ParenthesizedVariable.fir.kt              |   3 +
 .../deparenthesize/annotatedSafeCall.fir.kt   |   7 +
 .../checkDeparenthesizedType.fir.kt           |  30 ++
 .../deparenthesize/labeledSafeCall.fir.kt     |   3 +
 .../multiParenthesizedSafeCall.fir.kt         |   3 +
 .../parenthesizedSafeCall.fir.kt              |   3 +
 .../tests/deprecated/annotationUsage.fir.kt   |   9 +
 .../classWithCompanionObject.fir.kt           |   8 +
 .../deprecated/companionObjectUsage.fir.kt    |  32 ++
 .../tests/deprecated/componentUsage.fir.kt    |  11 +
 .../deprecated/deprecatedConstructor.fir.kt   |  34 ++
 .../tests/deprecated/deprecatedError.fir.kt   |  11 +
 .../deprecated/deprecatedErrorBuilder.fir.kt  |  21 +
 .../tests/deprecated/deprecatedHidden.fir.kt  |  11 +
 .../deprecated/deprecatedInheritance.fir.kt   | 140 +++++++
 .../deprecatedPropertyInheritance.fir.kt      | 135 +++++++
 .../tests/deprecated/functionUsage.fir.kt     |  51 +++
 .../deprecated/genericConstructorUsage.fir.kt |   8 +
 .../deprecated/hiddenPropertyAccessors.fir.kt |  40 ++
 .../deprecated/importJavaSamInterface.fir.kt  |  13 +
 .../tests/deprecated/imports.fir.kt           |   8 +
 .../tests/deprecated/iteratorUsage.fir.kt     |  24 ++
 .../tests/deprecated/javaDeprecated.fir.kt    |  16 +
 .../javaDeprecatedInheritance.fir.kt          |  53 +++
 .../tests/deprecated/javaDocDeprecated.fir.kt |  20 +
 .../tests/deprecated/nestedTypesUsage.fir.kt  |  18 +
 .../tests/deprecated/objectUsage.fir.kt       |   9 +
 .../tests/deprecated/propertyUsage.fir.kt     |  66 ++++
 .../propertyUseSiteTargetedAnnotations.fir.kt |  31 ++
 .../deprecated/propertyWithInvoke.fir.kt      |   6 +
 .../tests/deprecated/thisUsage.fir.kt         |   7 +
 .../tests/deprecated/typeUsage.fir.kt         |  42 ++
 .../typealiasCompanionObject.fir.kt           |  12 +
 .../deprecated/typealiasConstructor.fir.kt    |  17 +
 .../typealiasForDeprecatedClass.fir.kt        |  21 +
 .../tests/deprecated/typealiasUsage.fir.kt    |  24 ++
 .../tests/deprecated/unusedImport.fir.kt      |  10 +
 .../warningOnConstructorErrorOnClass.fir.kt   |   8 +
 .../accidentalOverrideFromGrandparent.fir.kt  |  14 +
 .../classFunctionOverriddenByProperty.fir.kt  |   8 +
 ...onOverriddenByPropertyInConstructor.fir.kt |   5 +
 ...unctionOverriddenByPropertyNoGetter.fir.kt |   7 +
 .../classPropertyOverriddenByFunction.fir.kt  |   8 +
 .../defaultFunction.fir.kt                    |   9 +
 ...legatedFunctionOverriddenByProperty.fir.kt |  10 +
 .../genericClassFunction.fir.kt               |   9 +
 .../overridesNothing.fir.kt                   |   7 +
 ...teClassFunctionOverriddenByProperty.fir.kt |   8 +
 .../accidentalOverrides/require.fir.kt        |   7 +
 .../traitFunctionOverriddenByProperty.fir.kt  |   8 +
 ...tFunctionOverriddenByPropertyNoImpl.fir.kt |   8 +
 .../traitPropertyOverriddenByFunction.fir.kt  |   8 +
 ...tPropertyOverriddenByFunctionNoImpl.fir.kt |   7 +
 .../bridges/class.fir.kt                      |  11 +
 .../bridges/fakeOverrideTrait.fir.kt          |   9 +
 .../bridges/trait.fir.kt                      |  11 +
 .../caseInProperties.fir.kt                   |   2 +
 .../clashFromInterfaceAndSuperClass.fir.kt    |  19 +
 .../erasure/collections.fir.kt                |   4 +
 .../erasure/delegateToTwoTraits.fir.kt        |  12 +
 .../erasure/delegationAndOwnMethod.fir.kt     |   9 +
 .../delegationToTraitImplAndOwnMethod.fir.kt  |  15 +
 .../erasure/extensionProperties.fir.kt        |   7 +
 .../erasure/genericType.fir.kt                |   6 +
 .../erasure/inheritFromTwoTraits.fir.kt       |  12 +
 .../erasure/kotlinAndJavaCollections.fir.kt   |   4 +
 .../erasure/nullableType.fir.kt               |   4 +
 .../superTraitAndDelegationToTraitImpl.fir.kt |  13 +
 .../erasure/twoTraitsAndOwnFunction.fir.kt    |  13 +
 .../erasure/typeMappedToJava.fir.kt           |   4 +
 .../erasure/typeParameter.fir.kt              |   4 +
 .../erasure/typeParameterWithBound.fir.kt     |   6 +
 .../erasure/typeParameterWithTwoBounds.fir.kt |   8 +
 .../typeParameterWithTwoBoundsInWhere.fir.kt  |   8 +
 .../enumMembers.fir.kt                        |   6 +
 .../waitNotifyGetClass.fir.kt                 |  19 +
 .../functionAndProperty/class.fir.kt          |   4 +
 .../functionAndProperty/classObject.fir.kt    |   6 +
 .../classPropertyInConstructor.fir.kt         |   3 +
 .../extensionFunctionAndNormalFunction.fir.kt |   6 +
 .../extensionPropertyAndFunction.fir.kt       |   7 +
 .../functionAndSetter.fir.kt                  |   7 +
 .../functionAndProperty/functionAndVar.fir.kt |   8 +
 .../functionAndProperty/localClass.fir.kt     |   6 +
 .../localClassInClass.fir.kt                  |   8 +
 .../functionAndProperty/nestedClass.fir.kt    |   6 +
 .../functionAndProperty/object.fir.kt         |   4 +
 .../objectExpression.fir.kt                   |   5 +
 .../objectExpressionInConstructor.fir.kt      |   6 +
 .../privateClassPropertyNoClash.fir.kt        |  13 +
 .../functionAndProperty/topLevel.fir.kt       |   2 +
 .../topLevelDifferentFiles.fir.kt             |   5 +
 .../functionAndProperty/topLevelGetter.fir.kt |   3 +
 .../functionAndProperty/trait.fir.kt          |   5 +
 .../functionAndProperty/withErrorTypes.fir.kt |   4 +
 .../duplicateJvmSignature/missingNames.fir.kt |  68 ++++
 .../specialNames/classObject.fir.kt           |   5 +
 .../classObjectCopiedField.fir.kt             |   8 +
 .../classObjectCopiedFieldObject.fir.kt       |  13 +
 .../specialNames/dataClassCopy.fir.kt         |   5 +
 .../specialNames/defaults.fir.kt              |   6 +
 .../specialNames/delegationBy.fir.kt          |   5 +
 .../specialNames/enum.fir.kt                  |   7 +
 .../specialNames/innerClassField.fir.kt       |   7 +
 .../specialNames/instance.fir.kt              |   3 +
 .../specialNames/propertyMetadataCache.fir.kt |  13 +
 .../duplicateJvmSignature/statics/jkjk.fir.kt |  34 ++
 .../kotlinClassExtendsJavaClass.fir.kt        |  22 ++
 ...assExtendsJavaClassExtendsJavaClass.fir.kt |  29 ++
 .../kotlinClassImplementsJavaInterface.fir.kt |  22 ++
 ...ntsJavaInterfaceExtendsJavaInteface.fir.kt |  29 ++
 ...otlinMembersVsJavaNonVisibleStatics.fir.kt |  24 ++
 .../synthesized/enumValuesValueOf.fir.kt      |  12 +
 .../traitImpl/oneTrait.fir.kt                 |   7 +
 ...FunctionOverriddenByPropertyInTrait.fir.kt |   8 +
 ...PropertyOverriddenByFunctionInTrait.fir.kt |   8 +
 .../traitImpl/twoTraits.fir.kt                |  11 +
 .../tests/duplicateJvmSignature/vararg.fir.kt |   8 +
 .../tests/dynamicTypes/delegationBy.fir.kt    |   5 +
 .../tests/dynamicTypes/unsupported.fir.kt     |   7 +
 .../withInvisibleSynthesized.fir.kt           |  35 ++
 .../tests/enum/AbstractEnum.fir.kt            |   3 +
 .../tests/enum/AbstractInEnum.fir.kt          |  47 +++
 .../tests/enum/AbstractOverrideInEnum.fir.kt  |  12 +
 .../enum/ConstructorCallFromOutside.fir.kt    |  10 +
 .../tests/enum/ExplicitConstructorCall.fir.kt |  10 +
 .../enum/InsideEntryConstructorCall.fir.kt    |  15 +
 .../InsideSecondaryConstructorCall.fir.kt     |  13 +
 .../tests/enum/NonPrivateConstructor.fir.kt   |   7 +
 .../enum/SecondaryConstructorCall.fir.kt      |   9 +
 .../tests/enum/classObjectInEnum.fir.kt       |   9 +
 .../enum/classObjectInEnumPrivate.fir.kt      |  10 +
 .../tests/enum/commonSupertype.fir.kt         |   7 +
 .../enum/compareTwoDifferentEnums.fir.kt      |  16 +
 ...onstructorWithDefaultParametersOnly.fir.kt |  21 +
 ...CreatePackageTypeForEnumEntry_after.fir.kt |  16 +
 ...reatePackageTypeForEnumEntry_before.fir.kt |  16 +
 .../tests/enum/emptyConstructor.fir.kt        |   4 +
 .../tests/enum/entryShouldBeOfEnumType.fir.kt |   9 +
 .../enumEntryCannotHaveClassObject.fir.kt     |  11 +
 .../tests/enum/enumEntryInAbstractEnum.fir.kt |  13 +
 .../tests/enum/enumImplementingTrait.fir.kt   |  21 +
 .../tests/enum/enumInheritance.fir.kt         |  11 +
 .../enum/enumIsAssignableToBuiltInEnum.fir.kt |  14 +
 .../tests/enum/enumMissingName.fir.kt         |   6 +
 .../tests/enum/enumModifier.fir.kt            |  15 +
 .../tests/enum/enumStarImport.fir.kt          |  20 +
 .../tests/enum/enumSubjectTypeCheck.fir.kt    |  40 ++
 .../enum/enumWithAnnotationKeyword.fir.kt     |   3 +
 .../tests/enum/enumWithEmptyName.fir.kt       |   2 +
 .../tests/enum/extendingEnumDirectly.fir.kt   |   9 +
 .../enum/extensionNamedAsEnumEntry.fir.kt     |   8 +
 .../diagnostics/tests/enum/ifEnumEntry.fir.kt |   6 +
 .../tests/enum/importEnumFromJava.fir.kt      |   7 +
 .../enum/incompatibleEnumEntryClasses.fir.kt  |  90 +++++
 .../tests/enum/incompatibleEnums.fir.kt       | 145 +++++++
 .../tests/enum/incompatibleEnums_1_4.fir.kt   | 145 +++++++
 .../tests/enum/inheritFromEnumEntry.fir.kt    |   5 +
 .../tests/enum/inheritanceFromEnum.fir.kt     |  13 +
 .../diagnostics/tests/enum/inline.fir.kt      |   3 +
 .../enum/inner/existingClassObject.fir.kt     |  19 +
 .../tests/enum/inner/insideClass.fir.kt       |   5 +
 .../tests/enum/inner/insideClassObject.fir.kt |   7 +
 .../tests/enum/inner/insideEnum.fir.kt        |   7 +
 .../enum/inner/insideEnumEntry_after.fir.kt   |   9 +
 .../enum/inner/insideEnumEntry_before.fir.kt  |   9 +
 .../inner/insideInnerClassNotAllowed.fir.kt   |   7 +
 .../tests/enum/inner/insideObject.fir.kt      |   5 +
 .../tests/enum/inner/insideTrait.fir.kt       |   5 +
 .../inner/redeclarationInClassObject.fir.kt   |  11 +
 .../tests/enum/inner/twoEnums.fir.kt          |   4 +
 .../twoEnumsInClassObjectAndInnerClass.fir.kt |   9 +
 .../enum/interfaceWithEnumKeyword.fir.kt      |   8 +
 .../diagnostics/tests/enum/isEnumEntry.fir.kt |   6 +
 .../tests/enum/javaEnumValueOfMethod.fir.kt   |  10 +
 .../tests/enum/javaEnumValuesMethod.fir.kt    |  11 +
 .../tests/enum/javaEnumWithAbstractFun.fir.kt |  16 +
 .../tests/enum/javaEnumWithFuns.fir.kt        |  16 +
 .../enum/javaEnumWithNameClashing.fir.kt      |  15 +
 .../tests/enum/javaEnumWithProperty.fir.kt    |  19 +
 .../diagnostics/tests/enum/kt2834.fir.kt      |   6 +
 .../tests/enum/kt8972_cloneNotAllowed.fir.kt  |   7 +
 .../diagnostics/tests/enum/localEnums.fir.kt  |  20 +
 .../tests/enum/modifiersOnEnumEntry.fir.kt    |  23 ++
 .../tests/enum/multipleConstructors.fir.kt    |   8 +
 .../tests/enum/openMemberInEnum.fir.kt        |  17 +
 .../enum/overrideFinalEnumMethods.fir.kt      |  11 +
 .../starImportNestedClassAndEntries.fir.kt    |  24 ++
 .../tests/enum/typeParametersInEnum.fir.kt    |   7 +
 ...aluesValueOfAndEntriesAccessibility.fir.kt |  18 +
 .../enum/wrongUnitializedEnumCompanion.fir.kt |   9 +
 .../evaluate/binaryMinusDepOnExpType.fir.kt   |  30 ++
 .../evaluate/binaryMinusIndepWoExpType.fir.kt |  36 ++
 .../binaryMinusIndependentExpType.fir.kt      |  24 ++
 .../tests/evaluate/divisionByZero.fir.kt      |  18 +
 .../diagnostics/tests/evaluate/float.fir.kt   |  10 +
 .../evaluate/floatLiteralOutOfRange.fir.kt    |  21 +
 .../infixFunOverBuiltinMemberInConst.fir.kt   |  10 +
 .../constructorOfUnsignedType.fir.kt          |  44 +++
 .../tests/evaluate/intOverflow.fir.kt         |  77 ++++
 .../intOverflowWithJavaProperties.fir.kt      |  14 +
 .../diagnostics/tests/evaluate/integer.fir.kt |  10 +
 .../tests/evaluate/logicWithNumber.fir.kt     |   8 +
 .../tests/evaluate/longOverflow.fir.kt        |  65 +++
 .../tests/evaluate/noOverflowWithZero.fir.kt  |  11 +
 .../evaluate/numberBinaryOperations.fir.kt    |  26 ++
 .../numberBinaryOperationsCall.fir.kt         |  31 ++
 .../numberBinaryOperationsInfixCall.fir.kt    |  31 ++
 .../tests/evaluate/otherOverflow.fir.kt       |   2 +
 .../tests/evaluate/parentesized.fir.kt        |  12 +
 .../evaluate/qualifiedExpressions.fir.kt      |   8 +
 .../evaluate/unaryMinusDepOnExpType.fir.kt    |  36 ++
 .../evaluate/unaryMinusIndepWoExpType.fir.kt  |  41 ++
 .../unaryMinusIndependentExpType.fir.kt       |  29 ++
 .../tests/evaluate/wrongLongSuffix.fir.kt     |  10 +
 .../diagnostics/tests/exposed/delegate.fir.kt |   6 +
 .../exposed/exceptionOnFakeInvisible.fir.kt   |  12 +
 .../tests/exposed/functional.fir.kt           |  12 +
 .../tests/exposed/implements.fir.kt           |   4 +
 .../tests/exposed/inaccessibleType.fir.kt     |  89 +++++
 .../diagnostics/tests/exposed/internal.fir.kt |  25 ++
 .../tests/exposed/internalAndProtected.fir.kt |  10 +
 .../tests/exposed/internalFromLocal.fir.kt    |  10 +
 .../diagnostics/tests/exposed/local.fir.kt    |  18 +
 .../tests/exposed/localFromInternal.fir.kt    |   7 +
 .../tests/exposed/localFromPrivate.fir.kt     |  15 +
 .../tests/exposed/localInFunReturnType.fir.kt |  60 +++
 .../tests/exposed/localInMemberType.fir.kt    |  21 +
 .../tests/exposed/localInPropertyType.fir.kt  |  60 +++
 .../diagnostics/tests/exposed/nested.fir.kt   |   6 +
 .../diagnostics/tests/exposed/object.fir.kt   |  30 ++
 .../tests/exposed/packagePrivate.fir.kt       |  35 ++
 .../tests/exposed/privateFromLocal.fir.kt     |  12 +
 ...privatePropertyInPrivateConstructor.fir.kt |   3 +
 ...propertyInConstructorOfPrivateClass.fir.kt |   3 +
 .../propertyInPrivateConstructor.fir.kt       |   3 +
 .../propertyInSimpleConstructor.fir.kt        |   3 +
 .../tests/exposed/protected.fir.kt            |  20 +
 .../tests/exposed/protectedInProtected.fir.kt |  12 +
 .../tests/exposed/protectedJava.fir.kt        |  16 +
 .../tests/exposed/protectedSameWay.fir.kt     |  13 +
 .../diagnostics/tests/exposed/simple.fir.kt   |  23 ++
 .../diagnostics/tests/exposed/typeArgs.fir.kt |  17 +
 .../extensions/ExtensionFunctions.fir.kt      |  76 ++++
 .../extensions/ExtensionsCalledOnSuper.fir.kt |  22 ++
 .../tests/extensions/GenericIterator.fir.kt   |  36 ++
 .../tests/extensions/GenericIterator2.fir.kt  |  15 +
 .../tests/extensions/classObject.fir.kt       |  20 +
 .../extensionMemberInClassObject.fir.kt       |  18 +
 .../extensionPropertyVsParameter.fir.kt       |   8 +
 .../tests/extensions/kt1875.fir.kt            |  22 ++
 .../tests/extensions/kt2317.fir.kt            |  15 +
 .../tests/extensions/kt3470.fir.kt            |   7 +
 .../tests/extensions/kt3563.fir.kt            |  17 +
 .../kt819ExtensionProperties.fir.kt           |  37 ++
 .../extensions/noClassObjectsInJava.fir.kt    |  11 +
 .../tests/extensions/object.fir.kt            |   6 +
 .../throwOutCandidatesByReceiver.fir.kt       |  56 +++
 .../throwOutCandidatesByReceiver2.fir.kt      |  15 +
 .../tests/extensions/variableInvoke.fir.kt    |  11 +
 .../tests/fileDependencyRecursion.fir.kt      |  15 +
 .../functionAsExpression/AutoLabels.fir.kt    |  11 +
 .../tests/functionAsExpression/Common.fir.kt  |  19 +
 .../DifficultInferenceForParameter.fir.kt     |   7 +
 .../ForbiddenNonLocalReturn.fir.kt            |  22 ++
 .../functionAsExpression/FunctionType.fir.kt  |  32 ++
 .../InferenceParametersTypes.fir.kt           |  20 +
 .../MissingParameterTypes.fir.kt              |  27 ++
 .../NameDeprecation.fir.kt                    |   9 +
 .../NoOverloadError.fir.kt                    |  18 +
 .../functionAsExpression/Parameters.fir.kt    |  18 +
 .../ReceiverByExpectedType.fir.kt             |   3 +
 .../ReturnAndLabels.fir.kt                    |   9 +
 .../ReturnTypeCheck.fir.kt                    |   9 +
 .../functionAsExpression/ScopeCheck.fir.kt    |  20 +
 .../WithGenericParameters.fir.kt              |  19 +
 .../WithOuterGeneric.fir.kt                   |  31 ++
 .../functionAsExpression/WithoutBody.fir.kt   |  12 +
 .../functionLiterals/DeprecatedSyntax.fir.kt  |  25 ++
 ...pectedParameterTypeMismatchVariance.fir.kt |  21 +
 .../ExpectedParametersTypesMismatch.fir.kt    |  45 +++
 .../LabeledFunctionLiterals.fir.kt            |  16 +
 .../assignmentOperationInLambda.fir.kt        |  17 +
 ...ntOperationInLambdaWithExpectedType.fir.kt |  16 +
 .../complexInference.fir.kt                   |  48 +++
 .../extensionComponents.fir.kt                |  53 +++
 .../inferredFunctionalType.fir.kt             |  34 ++
 .../destructuringInLambdas/modifiers.fir.kt   |  15 +
 .../noExpectedType.fir.kt                     |  32 ++
 .../redeclaration.fir.kt                      |  30 ++
 .../destructuringInLambdas/shadowing.fir.kt   |  25 ++
 .../destructuringInLambdas/simple.fir.kt      |  54 +++
 .../destructuringInLambdas/underscore.fir.kt  |  63 +++
 .../unsupportedFeature.fir.kt                 |  13 +
 .../unusedParameters.fir.kt                   |  43 ++
 ...onExpressionAsLastExpressionInBlock.fir.kt |  15 +
 .../functionLIteralInBlockInIf.fir.kt         |  10 +
 ...unctionLiteralAsArgumentForFunction.fir.kt |  25 ++
 .../functionLiteralInIf.fir.kt                |  15 +
 .../functionLiteralWithoutArgumentList.fir.kt |   7 +
 ...ericFunctionalTypeOnRHSOfPlusAssign.fir.kt |  11 +
 .../higherOrderCallMissingParameters.fir.kt   |  16 +
 .../tests/functionLiterals/kt11733.fir.kt     |  15 +
 .../tests/functionLiterals/kt11733_1.fir.kt   |  16 +
 .../tests/functionLiterals/kt16016.fir.kt     |   6 +
 .../tests/functionLiterals/kt2906.fir.kt      |  22 ++
 .../tests/functionLiterals/kt3343.fir.kt      |  25 ++
 .../tests/functionLiterals/kt4529.fir.kt      |  19 +
 ...t6541_extensionForExtensionFunction.fir.kt |  10 +
 .../tests/functionLiterals/kt6869.fir.kt      |  10 +
 .../kt7383_starProjectedFunction.fir.kt       |   7 +
 ...ixingTypeVariableForAnotherArgument.fir.kt |  14 +
 .../functionLiterals/return/AutoLabels.fir.kt |  22 ++
 .../return/AutoLabelsNonLocal.fir.kt          |  11 +
 .../ForbiddenNonLocalReturnNoType.fir.kt      |  19 +
 .../return/IfInReturnedExpression.fir.kt      |   9 +
 .../return/IfWithoutElse.fir.kt               |  15 +
 .../IfWithoutElseWithExplicitType.fir.kt      |  22 ++
 .../return/LambdaWithParameter.fir.kt         |  17 +
 .../LocalAndNonLocalReturnInLambda.fir.kt     |  11 +
 .../LocalReturnExplicitLabelNoParens.fir.kt   |   6 +
 .../LocalReturnExplicitLabelParens.fir.kt     |  12 +
 .../return/LocalReturnHasTypeNothing.fir.kt   |   7 +
 .../return/LocalReturnInNestedFunction.fir.kt |  12 +
 .../return/LocalReturnInNestedLambda.fir.kt   |  11 +
 .../return/LocalReturnNoCoercionToUnit.fir.kt |   7 +
 .../return/LocalReturnNull.fir.kt             |  14 +
 .../return/LocalReturnSecondUnit.fir.kt       |   6 +
 .../return/LocalReturnUnit.fir.kt             |   9 +
 .../LocalReturnUnitAndDontCareType.fir.kt     |  21 +
 .../LocalReturnUnitWithBodyExpression.fir.kt  |   7 +
 .../return/LocalReturnWithExpectedType.fir.kt |   9 +
 .../return/LocalReturnWithExplicitUnit.fir.kt |  16 +
 .../LocalReturnsWithExplicitReturnType.fir.kt |  10 +
 .../return/MixedReturnsFromLambda.fir.kt      |  14 +
 .../return/NoCommonSystem.fir.kt              |  19 +
 .../functionLiterals/return/SmartCast.fir.kt  |  19 +
 .../return/SmartCastWithExplicitType.fir.kt   |  17 +
 .../unresolvedReferenceInReturnBlock.fir.kt   |   9 +
 .../tests/functionLiterals/returnNull.fir.kt  |  10 +
 .../returnNullWithReturn.fir.kt               |  11 +
 .../underscopeParameters.fir.kt               |  48 +++
 .../functionLiterals/unusedLiteral.fir.kt     |  12 +
 .../unusedLiteralInsideUnitLiteral.fir.kt     |   8 +
 .../InconsistentTypeParameterBounds.fir.kt    |   7 +
 .../tests/generics/Projections.fir.kt         |  54 +++
 .../tests/generics/PseudoRawTypes.fir.kt      |  25 ++
 .../generics/RawTypeInIsExpression.fir.kt     |  14 +
 .../tests/generics/RawTypeInIsPattern.fir.kt  |  13 +
 .../generics/RecursiveUpperBoundCheck.fir.kt  |   3 +
 ...RecursiveUpperBoundWithTwoArguments.fir.kt |   1 +
 .../tests/generics/TypeParameterBounds.fir.kt |  23 ++
 ...TypeParametersInTypeParameterBounds.fir.kt |  15 +
 .../tests/generics/argumentsForT.fir.kt       |   7 +
 .../capturedParameters/captured.fir.kt        |  30 ++
 .../capturedParameters/innerLocalClass.fir.kt |  35 ++
 .../capturedParameters/localClass.fir.kt      |  25 ++
 .../localWithTypeParameter.fir.kt             |  22 ++
 .../capturedParameters/objectLiteral.fir.kt   |  23 ++
 .../capturedParameters/uncheckedCast.fir.kt   |  37 ++
 .../commonSupertypeContravariant.fir.kt       |  10 +
 .../commonSupertypeContravariant2.fir.kt      |   9 +
 .../generics/cyclicBounds/functions.fir.kt    |   7 +
 .../generics/cyclicBounds/inClass.fir.kt      |   7 +
 .../generics/doNotCaptureSupertype.fir.kt     |  15 +
 .../finalUpperBoundWithOverride.fir.kt        |  97 +++++
 .../finalUpperBoundWithoutOverride.fir.kt     |  82 ++++
 .../tests/generics/genericsInType.fir.kt      |  36 ++
 .../generics/innerClasses/bareTypes.fir.kt    |  20 +
 .../innerClasses/bareTypesComplex.fir.kt      |  14 +
 .../innerClasses/checkBoundsOuter.fir.kt      |   5 +
 .../fromCompanionObject_after.fir.kt          |  22 ++
 .../fromCompanionObject_before.fir.kt         |  22 ++
 .../fromOuterClassInObjectLiteral.fir.kt      |  15 +
 .../implicitArguments/fromSuperClasses.fir.kt |  26 ++
 .../fromSuperClassesLocal.fir.kt              |  55 +++
 .../fromSuperClassesLocalInsideInner.fir.kt   |  59 +++
 .../fromSuperClassesTransitive.fir.kt         |  19 +
 .../implicitArguments/inStaticScope.fir.kt    |   7 +
 .../implicitArguments/secondLevelDepth.fir.kt |  18 +
 .../innerClasses/importedInner.fir.kt         |  20 +
 .../innerClasses/innerSuperCall.fir.kt        |   9 +
 .../innerSuperCallSecondary.fir.kt            |  12 +
 .../generics/innerClasses/innerTP.fir.kt      |  42 ++
 .../innerClasses/innerUncheckedCast.fir.kt    |  32 ++
 .../innerClasses/innerVariance.fir.kt         |  14 +
 .../generics/innerClasses/iterator.fir.kt     |  37 ++
 .../tests/generics/innerClasses/j+k.fir.kt    |  28 ++
 .../generics/innerClasses/j+k_complex.fir.kt  |  35 ++
 .../tests/generics/innerClasses/kt3357.fir.kt |  18 +
 .../tests/generics/innerClasses/kt408.fir.kt  |  12 +
 .../tests/generics/innerClasses/kt6325.fir.kt |  21 +
 .../outerArgumentsRequired.fir.kt             |  23 ++
 .../innerClasses/parameterShadowing.fir.kt    |  18 +
 .../innerClasses/qualifiedOuter.fir.kt        |  24 ++
 .../qualifiedTypesResolution.fir.kt           |  51 +++
 .../tests/generics/innerClasses/simple.fir.kt |  36 ++
 .../generics/innerClasses/simpleIn.fir.kt     |  40 ++
 .../generics/innerClasses/simpleOut.fir.kt    |  37 ++
 .../innerClasses/simpleOutUseSite.fir.kt      |  37 ++
 .../substitutedMemberScope.fir.kt             |  49 +++
 .../invalidArgumentsNumberInWhere.fir.kt      |  19 +
 .../tests/generics/kt1575-Class.fir.kt        |   1 +
 .../tests/generics/kt1575-Function.fir.kt     |   2 +
 .../diagnostics/tests/generics/kt30590.fir.kt |   9 +
 .../diagnostics/tests/generics/kt5508.fir.kt  |  24 ++
 .../diagnostics/tests/generics/kt9203.fir.kt  |  11 +
 .../tests/generics/kt9203_1.fir.kt            |  18 +
 .../diagnostics/tests/generics/kt9985.fir.kt  |  46 +++
 .../conflictingReturnType.fir.kt              |  13 +
 .../flexibleTypes.fir.kt                      |  19 +
 .../mostSpecific.fir.kt                       |  13 +
 .../properties.fir.kt                         |  19 +
 .../propertiesConflict.fir.kt                 |  19 +
 .../multipleBoundsMemberScope/simple.fir.kt   |  14 +
 .../validTypeParameters.fir.kt                |  13 +
 .../capturedTypeWithPlatformSupertype.fir.kt  |  17 +
 ...rTypeNotNullOnlyIfItHasNotNullBound.fir.kt |   6 +
 ...stitutionForIncorporationConstraint.fir.kt |  17 +
 .../declarationsBoundsViolation.fir.kt        |  13 +
 .../expressionsBoundsViolation.fir.kt         |  19 +
 .../nullability/functionalBound.fir.kt        |  14 +
 ...TypeFromIntersectionOfNullableTypes.fir.kt |  38 ++
 .../tests/generics/nullability/kt25182.fir.kt |  14 +
 ...lSmartcastOnIntersectionOfNullables.fir.kt |  18 +
 .../generics/nullability/nullToGeneric.fir.kt |  35 ++
 .../nullability/smartCastRefinedClass.fir.kt  |  13 +
 .../generics/nullability/smartCasts.fir.kt    |  46 +++
 .../nullability/smartCastsOnThis.fir.kt       |  36 ++
 .../smartCastsValueArgument.fir.kt            |  52 +++
 .../nullability/tpBoundsViolation.fir.kt      |  49 +++
 .../tpBoundsViolationVariance.fir.kt          |  67 ++++
 .../generics/nullability/tpInBounds.fir.kt    |  40 ++
 .../generics/nullability/useAsReceiver.fir.kt |  27 ++
 .../nullability/useAsValueArgument.fir.kt     |  18 +
 .../generics/projectionsScope/MLOut.fir.kt    |  18 +
 .../generics/projectionsScope/addAll.fir.kt   |  32 ++
 .../approximateDispatchReceiver.fir.kt        |  14 +
 .../extensionReceiverTypeMismatch.fir.kt      |  18 +
 .../extensionResultSubstitution.fir.kt        |  13 +
 .../flexibleProjectedScope.fir.kt             |  16 +
 .../projectionsScope/inValueParameter.fir.kt  |   9 +
 .../iterateOnExtension.fir.kt                 |  11 +
 .../generics/projectionsScope/kt7296.fir.kt   |  15 +
 .../generics/projectionsScope/kt8647.fir.kt   |   8 +
 .../projectionsScope/lambdaArgument.fir.kt    |  16 +
 .../leakedApproximatedType.fir.kt             |  19 +
 .../multipleArgumentProjectedOut.fir.kt       |  10 +
 .../platformSuperClass.fir.kt                 |  23 ++
 .../projectedOutConventions.fir.kt            |  14 +
 .../projectedOutSmartCast.fir.kt              |  23 ++
 .../recursiveUpperBoundStar.fir.kt            |  14 +
 .../recursiveUpperBoundStarOut.fir.kt         |  12 +
 .../projectionsScope/starNullability.fir.kt   |  16 +
 .../starNullabilityRecursive.fir.kt           |   9 +
 .../projectionsScope/superClass.fir.kt        |  12 +
 .../typeMismatchConventions.fir.kt            |  20 +
 .../typeMismatchInLambda.fir.kt               |  27 ++
 .../typeParameterBounds.fir.kt                |  44 +++
 .../unsafeVarianceStar.fir.kt                 |  10 +
 .../generics/projectionsScope/varargs.fir.kt  |  13 +
 .../tests/generics/protectedSuperCall.fir.kt  |  21 +
 .../tests/generics/recursive.fir.kt           |  11 +
 ...esolveGenericBoundsBeforeSupertypes.fir.kt |   7 +
 .../generics/sameTypeParameterUse.fir.kt      |  15 +
 .../starProjections/checkBounds.fir.kt        |   3 +
 .../collectionInheritedFromJava.fir.kt        |  14 +
 .../starProjections/inheritedFromJava.fir.kt  |  14 +
 .../inheritedFromKotlin.fir.kt                |   9 +
 .../generics/starProjections/invalid.fir.kt   |  28 ++
 .../generics/suppressVarianceConflict.fir.kt  |  17 +
 .../tpAsReified/CapturedAsReified.fir.kt      |   9 +
 .../tpAsReified/ClassDereference.fir.kt       |   3 +
 .../generics/tpAsReified/Conventions.fir.kt   |  13 +
 .../GenericArrayAsReifiedArgument.fir.kt      |  19 +
 ...enericArrayAsReifiedArgumentWarning.fir.kt |  19 +
 .../GenericAsReifiedArgument.fir.kt           |  24 ++
 .../generics/tpAsReified/InConstructor.fir.kt |  17 +
 .../generics/tpAsReified/InFunction.fir.kt    |  18 +
 .../generics/tpAsReified/InProperty.fir.kt    |   2 +
 .../tests/generics/tpAsReified/InType.fir.kt  |   4 +
 .../tpAsReified/InlineableReified.fir.kt      |   8 +
 .../generics/tpAsReified/LocalFun.fir.kt      |   9 +
 .../tpAsReified/NotInlineableReified.fir.kt   |   4 +
 .../generics/tpAsReified/ReifiedClass.fir.kt  |   3 +
 .../unresolvedClassifierInWhere.fir.kt        |  14 +
 .../setterNotProjectedOutAssign.fir.kt        |  10 +
 .../setterProjectedOutAssign.fir.kt           |  14 +
 .../setterProjectedOutNoPlusAssign.fir.kt     |  11 +
 ...setterProjectedOutPlusAssignDefined.fir.kt |  13 +
 .../generics/wildcardInValueParameter.fir.kt  |  14 +
 ...rongNumberOfTypeArgumentsDiagnostic.fir.kt |  16 +
 .../tests/implicitIntersection.fir.kt         |  30 ++
 .../tests/implicitNestedIntersection.fir.kt   |  24 ++
 .../diagnostics/tests/implicitNothing.fir.kt  |  52 +++
 .../imports/AllUnderImportsAmbiguity.fir.kt   |  17 +
 .../AllUnderImportsLessPriority.fir.kt        |  17 +
 ...UnderImportsSamePriorityForFunction.fir.kt |  19 +
 ...UnderImportsSamePriorityForProperty.fir.kt |  19 +
 .../tests/imports/CheckJavaVisibility.fir.kt  |  73 ++++
 .../tests/imports/CheckJavaVisibility2.fir.kt |  62 +++
 .../tests/imports/CheckVisibility.fir.kt      |  28 ++
 .../tests/imports/ClassClash.fir.kt           |  81 ++++
 .../tests/imports/ClassClashStarImport.fir.kt |  76 ++++
 .../imports/ClassImportsConflicting.fir.kt    |  15 +
 .../CurrentPackageAndAllUnderImport.fir.kt    |  16 +
 .../CurrentPackageAndExplicitImport.fir.kt    |  16 +
 .../imports/DefaultImportsPriority.fir.kt     |   6 +
 .../imports/ExplicitImportsAmbiguity.fir.kt   |  17 +
 ...plicitImportsUnambiguityForFunction.fir.kt |  19 +
 .../ExplicitPackageImportsAmbiguity.fir.kt    |  17 +
 .../tests/imports/ImportClassClash.fir.kt     |  48 +++
 .../imports/ImportFromCompanionObject.fir.kt  | 138 +++++++
 .../ImportFromCurrentWithDifferentName.fir.kt |   8 +
 .../tests/imports/ImportFromObject.fir.kt     | 132 +++++++
 .../imports/ImportFromRootPackage.fir.kt      |  32 ++
 ...ImportHidingDefinitionInTheSameFile.fir.kt |   9 +
 .../ImportNestedWithDifferentName.fir.kt      |  10 +
 .../ImportObjectAndUseAsSupertype.fir.kt      |  19 +
 .../ImportObjectHidesCurrentPackage.fir.kt    |  12 +
 .../imports/ImportOverloadFunctions.fir.kt    |  45 +++
 .../tests/imports/ImportPrivateMember.fir.kt  |  37 ++
 .../ImportPrivateMemberFromOtherFile.fir.kt   |  26 ++
 .../ImportPrivateMembersWithStar.fir.kt       |  32 ++
 .../tests/imports/ImportProtectedClass.fir.kt |  14 +
 .../imports/ImportResolutionOrder.fir.kt      |  23 ++
 .../tests/imports/ImportTwoTimes.fir.kt       |  14 +
 .../tests/imports/ImportTwoTimesStar.fir.kt   |  14 +
 .../diagnostics/tests/imports/Imports.fir.kt  | 102 +++++
 .../tests/imports/ImportsConflicting.fir.kt   |  15 +
 .../imports/InaccessiblePrivateClass.fir.kt   |  18 +
 .../JavaPackageLocalClassNotImported.fir.kt   |  12 +
 .../tests/imports/MalformedImports.fir.kt     |   9 +
 .../tests/imports/NestedClassClash.fir.kt     |  31 ++
 .../imports/OperatorRenameOnImport.fir.kt     |  16 +
 .../PackageLocalClassNotImported.fir.kt       |  17 +
 .../PackageLocalClassReferencedError.fir.kt   |  11 +
 .../tests/imports/PackageVsClass.fir.kt       | 152 +++++++
 .../imports/PrivateClassNotImported.fir.kt    |  21 +
 .../PrivateClassReferencedError.fir.kt        |  14 +
 .../tests/imports/RenameOnImport.fir.kt       |  22 ++
 .../tests/imports/StarImportFromObject.fir.kt |  47 +++
 .../tests/imports/SyntaxError.fir.kt          |  60 +++
 .../imports/TopLevelClassVsPackage.fir.kt     |  68 ++++
 .../tests/imports/WrongImport.fir.kt          |  78 ++++
 .../importFunctionWithAllUnderImport.fir.kt   |  13 +
 ...nWithAllUnderImportAfterNamedImport.fir.kt |  22 ++
 .../invisibleFakeReferenceInImport.fir.kt     |  16 +
 .../diagnostics/tests/imports/kt13112.fir.kt  |  46 +++
 ...ropertyClassFileDependencyRecursion.fir.kt |  17 +
 .../tests/imports/twoImportLists.fir.kt       | 105 +++++
 .../NoSenselessComparisonForErrorType.fir.kt  |   9 +
 .../SupertypeOfErrorType.fir.kt               |  24 ++
 .../incompleteCode/arrayBracketsRange.fir.kt  |   9 +
 .../checkNothingIsSubtype.fir.kt              |  16 +
 .../controlStructuresErrors.fir.kt            |  26 ++
 .../arrayExpression.fir.kt                    |   8 +
 .../checkBackingFieldException.fir.kt         |  17 +
 ...pleteFunctionArgumentsOfNestedCalls.fir.kt |   8 +
 ...declarationAfterDotSelectorExpected.fir.kt |  29 ++
 .../declarationAfterIncompleteElvis.fir.kt    |  22 ++
 .../funEquals.fir.kt                          |   1 +
 .../funKeyword.fir.kt                         |   1 +
 .../funcitonTypes.fir.kt                      |   1 +
 .../incompleteEnumReference.fir.kt            |  11 +
 .../incompleteVal.fir.kt                      |   3 +
 .../incompleteValWithAccessor.fir.kt          |   3 +
 .../incompleteWhen.fir.kt                     |   3 +
 .../diagnosticWithSyntaxError/namedFun.fir.kt |   1 +
 .../noTypeParamsInReturnType.fir.kt           |  11 +
 .../typeReferenceError.fir.kt                 |   3 +
 .../valNoName.fir.kt                          |  43 ++
 ...eBeforeNextDeclarationWithModifiers.fir.kt |  15 +
 .../valWithNoNameInBlock.fir.kt               |  50 +++
 .../illegalSelectorCallableReference.fir.kt   |   8 +
 .../tests/incompleteCode/inExpr.fir.kt        |   5 +
 .../incompleteAssignment.fir.kt               |  30 ++
 .../incompleteCode/incompleteEquals.fir.kt    |   3 +
 .../incompleteTryCatchBlock.fir.kt            |  14 +
 .../tests/incompleteCode/kt1955.fir.kt        |   8 +
 .../tests/incompleteCode/kt2014.fir.kt        |  20 +
 .../kt4866UnresolvedArrayAccess.fir.kt        |   5 +
 .../incompleteCode/plusOnTheRight.fir.kt      |  11 +
 .../pseudocodeTraverseNextInstructions.fir.kt |   8 +
 .../senselessComparisonWithNull.fir.kt        |   6 +
 .../typeParameterOnLhsOfDot.fir.kt            |   8 +
 .../incompleteCode/unresolvedArguments.fir.kt |  13 +
 .../incompleteCode/unresolvedOperation.fir.kt |   4 +
 .../variableDeclarationInSelector.fir.kt      |   4 +
 .../NoInferenceFromDeclaredBounds.fir.kt      |  12 +
 .../cannotCompleteResolveAmbiguity.fir.kt     |   9 +
 ...ompleteResolveFunctionLiteralsNoUse.fir.kt |   7 +
 ...otCompleteResolveNoInfoForParameter.fir.kt |  11 +
 ...cannotCompleteResolveNoneApplicable.fir.kt |   8 +
 ...CompleteResolveWithFunctionLiterals.fir.kt |  11 +
 .../capturedInProjectedFlexibleType.fir.kt    |  16 +
 .../approximateBeforeFixation.fir.kt          |   8 +
 .../cannotCaptureInProjection.fir.kt          |  17 +
 .../captureForNullableTypes.fir.kt            |  19 +
 .../captureForPlatformTypes.fir.kt            |  27 ++
 .../captureFromNullableTypeVariable.fir.kt    |  14 +
 .../capturedTypes/captureFromSubtyping.fir.kt |   9 +
 .../captureFromTypeParameterUpperBound.fir.kt |  11 +
 .../captureTypeOnlyOnTopLevel.fir.kt          |  10 +
 .../capturedTypes/capturedType.fir.kt         |  16 +
 .../capturedTypeAndApproximation.fir.kt       |  16 +
 ...peSubstitutedIntoOppositeProjection.fir.kt |  14 +
 .../capturedTypeWithInnerTypealias.fir.kt     |  12 +
 ...pturedTypeWithTypeVariableSubtyping.fir.kt |  22 ++
 .../expectedTypeMismatchWithInVariance.fir.kt |  10 +
 .../invokeCallWithCapturedReceiver.fir.kt     |  10 +
 .../inference/capturedTypes/kt25302.fir.kt    |  18 +
 .../inference/capturedTypes/kt2570.fir.kt     |   9 +
 .../inference/capturedTypes/kt2872.fir.kt     |   7 +
 .../memberScopeOfCaptured.fir.kt              |  12 +
 .../noCaptureTypeErrorForNonTopLevel.fir.kt   |  19 +
 .../notApproximateWhenCopyDescriptors.fir.kt  |   7 +
 .../overApproximationForInCaptured.fir.kt     |   8 +
 .../overApproximationForOutCaptured.fir.kt    |   8 +
 ...lailityOnSupertypesWhenCaptureTypes.fir.kt |  23 ++
 .../starProjectionRegression.fir.kt           |  17 +
 .../topLevelCapturingInsideReturnType.fir.kt  |  11 +
 .../coerceFunctionLiteralToSuspend.fir.kt     |  29 ++
 ...ToUnitForIfAsLastExpressionInLambda.fir.kt |  42 ++
 ...coercionToUnitForLastLambdaInLambda.fir.kt |  13 +
 .../coercionWithExpectedType.fir.kt           |  26 ++
 .../coercionWithExpectedTypeAndBound.fir.kt   |  13 +
 .../coercionWithExplicitTypeArgument.fir.kt   |  10 +
 .../coercionWithoutExpectedType.fir.kt        |  19 +
 .../indirectCoercionWithExpectedType.fir.kt   |  36 ++
 .../inference/coercionToUnit/kt30242.fir.kt   |  64 +++
 .../coercionToUnit/noCoercion.fir.kt          |  26 ++
 ...nOfCoercionToUnitInsideNestedLambda.fir.kt |  52 +++
 .../boundOnNullableVariable.fir.kt            |   6 +
 ...ullableChildAndNonParameterizedType.fir.kt |  20 +
 ...tWithTypeContainingNonFixedVariable.fir.kt |  88 +++++
 .../dontCaptureTypeVariable.fir.kt            |  11 +
 .../fixVariablesInRightOrder.fir.kt           |  17 +
 .../genericCandidateInGenericClass.fir.kt     |   9 +
 .../inferenceWithUpperBoundsInLambda.fir.kt   |  13 +
 .../inference/commonSystem/kt30300.fir.kt     |  21 +
 .../inference/commonSystem/kt31969.fir.kt     |  12 +
 .../inference/commonSystem/kt32818.fir.kt     |   5 +
 .../inference/commonSystem/kt33197.fir.kt     |  19 +
 .../commonSystem/kt3372toCollection.fir.kt    |  12 +
 ...eForArgumentCallWithExactAnnotation.fir.kt |  17 +
 ...rArgumentCallWithExactAnnotation_ni.fir.kt |  17 +
 .../manyArgumentsForVararg.fir.kt             | 178 +++++++++
 .../commonSystem/nestedLambdas.fir.kt         |  10 +
 .../nonFixedVariableFromBothBranches.fir.kt   |  20 +
 .../nonFixedVariableInsideFlexibleType.fir.kt |  30 ++
 .../outProjectedTypeToOutProjected.fir.kt     |  12 +
 ...tponedCompletionWithExactAnnotation.fir.kt |  28 ++
 ...nedCompletionWithExactAnnotation_ni.fir.kt |  39 ++
 ...tFromCovariantAndContravariantTypes.fir.kt |  20 +
 .../selectFromTwoIncompatibleTypes.fir.kt     |  24 ++
 .../selectIntegerValueTypeFromIf.fir.kt       |   8 +
 .../commonSystem/theSameFunctionInArgs.fir.kt |   6 +
 .../completeInferenceIfManyFailed.fir.kt      |  17 +
 .../inference/conflictingSubstitutions.fir.kt |  20 +
 ...FromVariantTypeWithNestedProjection.fir.kt |  16 +
 .../constraintOnFunctionLiteral.fir.kt        |  12 +
 ...initelyNotNullTypeInvariantPosition.fir.kt |  24 ++
 .../earlyCompletionForCalls.fir.kt            |  15 +
 .../equalityConstraintOnNullableType.fir.kt   |  19 +
 .../errorUpperBoundConstraint.fir.kt          |  26 ++
 ...onstraintEarlierThanComplexVariable.fir.kt |  16 +
 ...noreConstraintFromImplicitInNothing.fir.kt |  16 +
 ...inferTypeFromCapturedStarProjection.fir.kt |   5 +
 .../tests/inference/constraints/kt6320.fir.kt |  21 +
 ...t7351ConstraintFromUnitExpectedType.fir.kt |  19 +
 .../tests/inference/constraints/kt7433.fir.kt |   9 +
 .../tests/inference/constraints/kt8879.fir.kt |  13 +
 ...anyConstraintsDueToFlexibleRawTypes.fir.kt |  32 ++
 ...RecursiveFlexibleTypesWithWildcards.fir.kt |  32 ++
 .../notNullConstraintOnNullableType.fir.kt    |  25 ++
 .../operationsOnIntegerValueTypes.fir.kt      |   9 +
 ...recursiveJavaTypeWithStarProjection.fir.kt |  22 ++
 ...aintContainingTypeWithoutProjection.fir.kt |  30 ++
 .../constraints/returnLambdaFromLambda.fir.kt |  22 ++
 .../subtypeConstraintOnNullableType.fir.kt    |  22 ++
 .../supertypeConstraintOnNullableType.fir.kt  |  22 ++
 ...tionWithDefNotNullTypesAndDelegates.fir.kt |  15 +
 .../inference/dependOnExpectedType.fir.kt     |  53 +++
 .../inference/dependantOnVariance.fir.kt      |  69 ++++
 .../dependantOnVarianceNullable.fir.kt        |  14 +
 .../expectedTypeAdditionalTest.fir.kt         |  13 +
 .../expectedTypeDoubleReceiver.fir.kt         |  20 +
 .../inference/expectedTypeFromCast.fir.kt     |  21 +
 ...pectedTypeFromCastComplexExpression.fir.kt |  16 +
 .../expectedTypeFromCastParenthesized.fir.kt  |  22 ++
 .../inference/expectedTypeWithGenerics.fir.kt |  18 +
 .../tests/inference/findViewById.fir.kt       |  59 +++
 .../inference/fixVariableToNothing.fir.kt     |  15 +
 .../fixationOrderForProperConstraints.fir.kt  |   7 +
 .../flexibleTypesAsUpperBound.fir.kt          |  13 +
 .../inference/functionPlaceholderError.fir.kt |  15 +
 .../genericAssignmentOperator.fir.kt          |   9 +
 .../hasErrorInConstrainingTypes.fir.kt        |   8 +
 .../tests/inference/immutableArrayList.fir.kt |  17 +
 ...vokeExtensionWithFunctionalArgument.fir.kt |  29 ++
 ...mpanionObjectWithFunctionalArgument.fir.kt |  17 +
 ...nvokeInObjectWithFunctionalArgument.fir.kt |  15 +
 ...itInvokeWithFunctionLiteralArgument.fir.kt |  38 ++
 .../inference/inferInFunctionLiterals.fir.kt  |  12 +
 .../inferInFunctionLiteralsWithReturn.fir.kt  |  12 +
 ...sectionTypeMultipleBoundsAsReceiver.fir.kt |  13 +
 .../inference/invokeLambdaAsFunction.fir.kt   |   7 +
 .../inference/knownTypeParameters.fir.kt      |  30 ++
 .../tests/inference/kt11963.fir.kt            |   1 +
 .../tests/inference/kt12399.fir.kt            |   3 +
 .../diagnostics/tests/inference/kt1293.fir.kt |  12 +
 .../tests/inference/kt28598.fir.kt            |  85 ++++
 .../tests/inference/kt28654.fir.kt            |  10 +
 .../tests/inference/kt30405.fir.kt            |  16 +
 .../diagnostics/tests/inference/kt3184.fir.kt |  26 ++
 .../tests/inference/kt32415.fir.kt            |   9 +
 .../tests/inference/kt32434.fir.kt            |  32 ++
 .../diagnostics/tests/inference/kt6175.fir.kt |  49 +++
 .../diagnostics/tests/inference/kt619.fir.kt  |   4 +
 ...alInitializerWithAnonymousFunctions.fir.kt |   9 +
 .../tests/inference/listConstructor.fir.kt    |  30 ++
 .../localFunctionInsideIfBlock.fir.kt         |  10 +
 .../tests/inference/mapFunction.fir.kt        |  35 ++
 .../mostSpecificAfterInference.fir.kt         |  24 ++
 .../inference/nestedCalls/arrayAccess.fir.kt  |  11 +
 .../nestedCalls/binaryExpressions.fir.kt      |  72 ++++
 .../checkTypesForQualifiedProperties.fir.kt   |   9 +
 ...eteNestedCallsForArraySetExpression.fir.kt |   8 +
 .../completeNestedCallsInference.fir.kt       |  19 +
 ...leteNestedForVariableAsFunctionCall.fir.kt |  16 +
 .../nestedCalls/externalTypeParameter.fir.kt  |   6 +
 .../inferenceForNestedBinaryCall.fir.kt       |  12 +
 .../tests/inference/nestedCalls/kt3395.fir.kt |  35 ++
 .../nestedCalls/kt3461checkTypes.fir.kt       |  15 +
 .../nestedCalls/makeNullableIfSafeCall.fir.kt |  41 ++
 .../nontrivialCallExpression.fir.kt           |  18 +
 .../noInformationForParameter.fir.kt          |  15 +
 ...ancyOnVariableWithTrivialConstraint.fir.kt |  15 +
 ...erateConstraintWithInnerNothingType.fir.kt |  13 +
 ...implicitNothingConstraintFromReturn.fir.kt |  15 +
 .../inference/nothingType/kt24490.fir.kt      |  13 +
 .../inference/nothingType/kt32051.fir.kt      |  32 ++
 .../inference/nothingType/kt32081.fir.kt      |  10 +
 .../inference/nothingType/kt32207.fir.kt      |  15 +
 .../inference/nothingType/kt32388.fir.kt      |  13 +
 .../lambdaNothingAndExpectedType.fir.kt       |  12 +
 ...ferenceWithIncorporationOfVariables.fir.kt |  12 +
 .../nothingWithCallableReference.fir.kt       |  31 ++
 .../platformNothingAsUsefulConstraint.fir.kt  |  35 ++
 ...leTypeArgumentWithNotNullUpperBound.fir.kt |  11 +
 .../tests/inference/nullableUpperBound.fir.kt |   9 +
 .../tests/inference/opposite.fir.kt           |  11 +
 .../possibleCycleOnConstraints.fir.kt         |  14 +
 .../inference/recursiveCalls/kt23531.fir.kt   |  19 +
 .../recursiveLocalFuns/localFactorial.fir.kt  |  12 +
 .../recursiveLocalFuns/recursiveFun.fir.kt    |   4 +
 .../recursiveLocalFuns/recursiveLambda.fir.kt |   6 +
 .../recursiveLocalFuns/selfCall.fir.kt        |   9 +
 .../tests/inference/recursiveTypes.fir.kt     |  15 +
 .../inference/regressions/compareBy.fir.kt    |   9 +
 .../tests/inference/regressions/kt1029.fir.kt |  17 +
 .../tests/inference/regressions/kt1031.fir.kt |  21 +
 .../tests/inference/regressions/kt1127.fir.kt |  10 +
 .../tests/inference/regressions/kt1145.fir.kt |  15 +
 .../tests/inference/regressions/kt1358.fir.kt |  12 +
 .../tests/inference/regressions/kt1410.fir.kt |  26 ++
 .../tests/inference/regressions/kt1718.fir.kt |  17 +
 .../tests/inference/regressions/kt1944.fir.kt |  14 +
 .../tests/inference/regressions/kt2057.fir.kt |  11 +
 .../tests/inference/regressions/kt2179.fir.kt |  46 +++
 .../tests/inference/regressions/kt2200.fir.kt |  18 +
 .../tests/inference/regressions/kt2283.fir.kt |  14 +
 .../tests/inference/regressions/kt2286.fir.kt |  28 ++
 .../tests/inference/regressions/kt2294.fir.kt |  18 +
 .../tests/inference/regressions/kt2320.fir.kt |  13 +
 .../tests/inference/regressions/kt2324.fir.kt |  35 ++
 .../tests/inference/regressions/kt2407.fir.kt |  18 +
 .../tests/inference/regressions/kt2445.fir.kt |  12 +
 .../tests/inference/regressions/kt2459.fir.kt |  10 +
 .../tests/inference/regressions/kt2484.fir.kt |  18 +
 .../tests/inference/regressions/kt2505.fir.kt |  22 ++
 .../tests/inference/regressions/kt2514.fir.kt |  16 +
 .../tests/inference/regressions/kt2588.fir.kt |  18 +
 .../tests/inference/regressions/kt2741.fir.kt |  11 +
 .../tests/inference/regressions/kt2754.fir.kt |  28 ++
 .../tests/inference/regressions/kt2838.fir.kt |  19 +
 .../tests/inference/regressions/kt2841.fir.kt |  15 +
 .../inference/regressions/kt2841_it.fir.kt    |  18 +
 .../regressions/kt2841_it_this.fir.kt         |  19 +
 .../inference/regressions/kt2841_this.fir.kt  |  18 +
 .../tests/inference/regressions/kt2842.fir.kt |  27 ++
 .../tests/inference/regressions/kt2883.fir.kt |  33 ++
 .../tests/inference/regressions/kt3007.fir.kt |  43 ++
 .../tests/inference/regressions/kt3038.fir.kt |  22 ++
 .../tests/inference/regressions/kt3150.fir.kt |  24 ++
 .../tests/inference/regressions/kt3174.fir.kt |  12 +
 .../inference/regressions/kt32862_both.fir.kt |  16 +
 .../inference/regressions/kt32862_none.fir.kt |  11 +
 .../tests/inference/regressions/kt3301.fir.kt |  20 +
 .../tests/inference/regressions/kt3344.fir.kt |  16 +
 .../inference/regressions/kt34029.fir.kt      |   6 +
 .../inference/regressions/kt34282.fir.kt      |  10 +
 .../tests/inference/regressions/kt3496.fir.kt |   9 +
 .../inference/regressions/kt3496_2.fir.kt     |  11 +
 .../tests/inference/regressions/kt3559.fir.kt |  10 +
 .../tests/inference/regressions/kt4420.fir.kt |  10 +
 .../tests/inference/regressions/kt702.fir.kt  |  20 +
 .../tests/inference/regressions/kt731.fir.kt  |  19 +
 .../tests/inference/regressions/kt742.fir.kt  |  13 +
 .../tests/inference/regressions/kt8132.fir.kt |  11 +
 .../tests/inference/regressions/kt832.fir.kt  |  11 +
 .../tests/inference/regressions/kt943.fir.kt  |  22 ++
 .../tests/inference/regressions/kt9461.fir.kt |  17 +
 .../tests/inference/regressions/kt948.fir.kt  |  23 ++
 ...tlinFunctionAsSyntheticJavaAccessor.fir.kt |   3 +
 ...boutUnresolvedReferenceAsUnresolved.fir.kt |   7 +
 .../ErrorTypeAsGenericParameter.fir.kt        |   9 +
 .../FunctionPlaceholder.fir.kt                |  17 +
 ...oAmbiguityForDifferentFunctionTypes.fir.kt |  16 +
 ...nnotInferParameterTypeWithInference.fir.kt |  17 +
 .../inferTypeFromUnresolvedArgument.fir.kt    |  13 +
 ...renceWrongReceiverForManyCandidates.fir.kt |   8 +
 ...ubtypeForInvariantWithErrorGenerics.fir.kt |  13 +
 .../typeInferenceFailedOnComponentN.fir.kt    |  10 +
 .../typeInferenceFailedOnIteratorCall.fir.kt  |   9 +
 .../wrongArgumentExtensionFunction.fir.kt     |   8 +
 ...umentPassedToLocalExtensionFunction.fir.kt |  21 +
 .../delegationAndInference.fir.kt             |  14 +
 ...9returnTypeWithTypealiasSubtitution.fir.kt |  22 ++
 ...ithTypealiasSubtitutionOldInference.fir.kt |  22 ++
 .../kt6081SubstituteIntoClassCorrectly.fir.kt |  14 +
 ...CheckTypeArgumentsNotTypeParameters.fir.kt |  10 +
 .../substitutionIntoAnonymousClass.fir.kt     |  25 ++
 .../substitutionIntoInnerClass.fir.kt         |  22 ++
 ...yNumberLowerBoundsBeforeUpperBounds.fir.kt |   6 +
 .../inference/typeConstructorMismatch.fir.kt  |  14 +
 .../typeInferenceExpectedTypeMismatch.fir.kt  |  42 ++
 .../typeParameterInConstructor.fir.kt         |   5 +
 ...flictingSubstitutionsFromUpperBound.fir.kt |  12 +
 .../doNotInferFromBoundsOnly.fir.kt           |  68 ++++
 .../upperBounds/intersectUpperBounds.fir.kt   |  33 ++
 .../tests/inference/upperBounds/kt2856.fir.kt |  20 +
 .../upperBounds/nonNullUpperBound.fir.kt      |  13 +
 .../typeParameterAsUpperBound.fir.kt          |  16 +
 .../useBoundsIfUnknownParameters.fir.kt       |  12 +
 .../useBoundsToInferTypeParamsSimple.fir.kt   |  23 ++
 .../useFunctionLiteralsToInferType.fir.kt     |  16 +
 .../infos/PropertiesWithBackingFields.fir.kt  |  59 +++
 .../diagnostics/tests/infos/SmartCasts.fir.kt | 228 +++++++++++
 .../tests/inline/anonymousObjects.fir.kt      |  12 +
 .../tests/inline/assignment.fir.kt            |  14 +
 .../inline/binaryExpressions/andOr.fir.kt     |  17 +
 .../binaryExpressions/arrayAccess.fir.kt      |  22 ++
 .../binaryExpressions/assignment.fir.kt       |  30 ++
 .../binaryExpressions/comparison.fir.kt       |  26 ++
 .../binaryExpressions/componentAccess.fir.kt  |  18 +
 .../inline/binaryExpressions/contains.fir.kt  |  24 ++
 .../binaryExpressions/mathOperations.fir.kt   |  34 ++
 .../inline/binaryExpressions/rangeTo.fir.kt   |  29 ++
 .../diagnostics/tests/inline/capture.fir.kt   |  51 +++
 .../tests/inline/constructor.fir.kt           |   7 +
 .../diagnostics/tests/inline/default.fir.kt   |  15 +
 .../inline/defaultLambdaInlineDisable.fir.kt  |  48 +++
 .../inline/defaultLambdaInlineSuspend.fir.kt  |  10 +
 .../tests/inline/defaultLambdaInlining.fir.kt |  47 +++
 .../tests/inline/extensionOnFunction.fir.kt   |  28 ++
 .../tests/inline/fromInlineToNoInline.fir.kt  |   7 +
 .../diagnostics/tests/inline/functions.fir.kt |  12 +
 ...nlineLambdaInDefaultInlineParameter.fir.kt |  58 +++
 ...bdaInDefaultInlineParameterDisabled.fir.kt |  61 +++
 .../tests/inline/inlineReified.fir.kt         |   2 +
 .../diagnostics/tests/inline/invoke.fir.kt    |  26 ++
 .../diagnostics/tests/inline/isCheck.fir.kt   |  10 +
 .../diagnostics/tests/inline/kt15410.fir.kt   |  10 +
 .../diagnostics/tests/inline/kt19679.fir.kt   |   4 +
 .../diagnostics/tests/inline/kt4869.fir.kt    |   6 +
 .../diagnostics/tests/inline/labeled.fir.kt   |  40 ++
 .../tests/inline/lambdaCast.fir.kt            |   9 +
 .../diagnostics/tests/inline/localFun.fir.kt  |   4 +
 .../messagesForUnsupportedInInline.fir.kt     |  18 +
 .../nonLocalReturns/anonymousObjects.fir.kt   |  23 ++
 .../anonymousObjectsNested.fir.kt             |  48 +++
 .../nonLocalReturns/explicitReturnType.fir.kt |  41 ++
 .../nonLocalReturns/fromOnlyLocal.fir.kt      |   8 +
 .../nonLocalReturns/inlineLambda.fir.kt       |  16 +
 .../nonLocalReturns/labeledReturn.fir.kt      |  31 ++
 .../nonLocalReturns/lambdaAsGeneric.fir.kt    |  13 +
 .../lambdaAsNonFunction.fir.kt                |  11 +
 ...WithGlobalReturnsInsideOnlyLocalOne.fir.kt |   9 +
 .../inline/nonLocalReturns/localFun.fir.kt    |  15 +
 .../nonLocalReturns/nestedNonLocals.fir.kt    |  41 ++
 .../nonLocalReturns/noInlineAnnotation.fir.kt |  10 +
 .../nonLocalReturns/noInlineLambda.fir.kt     |  13 +
 .../nonLocalReturns/nonInlinedClass.fir.kt    |  23 ++
 .../onlyLocalReturnLambda.fir.kt              |  43 ++
 .../onlyLocalReturnLambdaBinaryExpr.fir.kt    |  25 ++
 .../propertyAccessorsAndConstructor.fir.kt    |  24 ++
 .../inline/nonLocalReturns/toOnlyLocal.fir.kt |   8 +
 .../nonPublicMember/inNonPublicClass.fir.kt   |  47 +++
 .../inNonPublicInnerClass.fir.kt              |  36 ++
 .../inline/nonPublicMember/inPackage.fir.kt   |  27 ++
 .../nonPublicMember/inPublicClass.fir.kt      |  37 ++
 .../inline/nonPublicMember/kt14887.fir.kt     |   8 +
 .../inline/nonPublicMember/localClass.fir.kt  |  15 +
 .../inline/nonPublicMember/localClass2.fir.kt |  13 +
 .../inline/nonPublicMember/localFun.fir.kt    |  11 +
 .../nonPublicMember/publishedApi.fir.kt       |  48 +++
 .../inline/nonVirtualMembersWithInline.fir.kt |  47 +++
 .../tests/inline/nothingToInline.fir.kt       |  29 ++
 .../tests/inline/nullabilityOperations.fir.kt |  16 +
 .../tests/inline/nullableFunction.fir.kt      |  21 +
 .../tests/inline/overrideWithInline.fir.kt    |  60 +++
 .../tests/inline/parenthesized.fir.kt         |  27 ++
 .../tests/inline/privateClass.fir.kt          |  25 ++
 .../tests/inline/propagation.fir.kt           |  37 ++
 .../tests/inline/property/invoke.fir.kt       |  20 +
 .../property/propertyWithBackingField.fir.kt  |  21 +
 .../property/unsupportedConstruction.fir.kt   |  20 +
 .../inline/property/virtualProperty.fir.kt    |  38 ++
 .../inline/protectedCallDepecation.fir.kt     | 102 +++++
 .../tests/inline/protectedCallError.fir.kt    | 102 +++++
 .../tests/inline/publishedApi.fir.kt          | 175 +++++++++
 .../diagnostics/tests/inline/recursion.fir.kt |  24 ++
 .../tests/inline/regressions/kt4341.fir.kt    |   6 +
 .../diagnostics/tests/inline/returns.fir.kt   |  20 +
 .../diagnostics/tests/inline/sam.fir.kt       |  58 +++
 .../tests/inline/stringTemplate.fir.kt        |  10 +
 .../unaryExpressions/mathOperation.fir.kt     |  35 ++
 .../inline/unaryExpressions/notOnCall.fir.kt  |   3 +
 .../unaryExpressions/notOperation.fir.kt      |  21 +
 .../inline/unsupportedConstruction.fir.kt     |  33 ++
 .../diagnostics/tests/inline/vararg.fir.kt    |  16 +
 .../diagnostics/tests/inline/when.fir.kt      |  11 +
 .../tests/inline/wrongUsage.fir.kt            |  51 +++
 .../basicInlineClassDeclaration.fir.kt        |   8 +
 ...basicInlineClassDeclarationDisabled.fir.kt |  10 +
 .../constructorsJvmSignaturesClash.fir.kt     |  18 +
 .../delegatedPropertyInInlineClass.fir.kt     |  28 ++
 .../functionsJvmSignaturesClash.fir.kt        |  37 ++
 ...sJvmSignaturesConflictOnInheritance.fir.kt |  14 +
 ...identityComparisonWithInlineClasses.fir.kt |  15 +
 ...lineClassCanOnlyImplementInterfaces.fir.kt |  13 +
 ...annotImplementInterfaceByDelegation.fir.kt |   9 +
 ...onstructorParameterWithDefaultValue.fir.kt |   3 +
 .../inlineClassDeclarationCheck.fir.kt        |  33 ++
 .../inlineClassImplementsCollection.fir.kt    |  12 +
 ...ineClassWithForbiddenUnderlyingType.fir.kt |  16 +
 .../inlineClassesInsideAnnotations.fir.kt     |  12 +
 .../lateinitInlineClasses.fir.kt              |  10 +
 ...OfInitializerBlockInsideInlineClass.fir.kt |  10 +
 ...licPrimaryConstructorForInlineClass.fir.kt |   7 +
 ...sWithBackingFieldsInsideInlineClass.fir.kt |  34 ++
 .../recursiveInlineClasses.fir.kt             |  21 +
 ...mbersAndConstructsInsideInlineClass.fir.kt |  45 +++
 ...dLiteralsWithoutArtifactOnClasspath.fir.kt |   3 +
 ...arargsOnParametersOfInlineClassType.fir.kt |  21 +
 .../tests/inner/InnerClassNameClash.fir.kt    |  10 +
 .../inner/accessingToJavaNestedClass.fir.kt   |  64 +++
 .../inner/accessingToKotlinNestedClass.fir.kt |  44 +++
 .../tests/inner/annotationInInnerClass.fir.kt |   5 +
 .../inner/classesInClassObjectHeader.fir.kt   |  11 +
 .../tests/inner/constructorAccess.fir.kt      |  32 ++
 .../tests/inner/deepInnerClass.fir.kt         |  14 +
 .../tests/inner/enumEntries.fir.kt            |  12 +
 .../tests/inner/enumInInnerClass.fir.kt       |   5 +
 .../tests/inner/extensionFun.fir.kt           |  28 ++
 .../extensionLambdaInsideNestedClass.fir.kt   |  27 ++
 .../tests/inner/illegalModifier.fir.kt        |  45 +++
 .../tests/inner/illegalModifier_lv12.fir.kt   |  45 +++
 ...rClassInEnumEntryClassMemberResolve.fir.kt |  13 +
 .../innerClassInEnumEntryClass_lv11.fir.kt    |  19 +
 .../innerClassInEnumEntryClass_lv12.fir.kt    |  19 +
 .../innerClassInEnumEntryClass_lv13.fir.kt    |  19 +
 .../innerClassesInStaticParameters.fir.kt     |  11 +
 .../innerConstructorsFromQualifiers.fir.kt    |  36 ++
 ...omQualifiersWithIrrelevantCandidate.fir.kt |  43 ++
 .../inner/innerErrorForClassObjects.fir.kt    |  26 ++
 .../tests/inner/innerErrorForObjects.fir.kt   |  27 ++
 .../tests/inner/innerThisSuper.fir.kt         |  22 ++
 .../tests/inner/interfaceInInnerClass.fir.kt  |   5 +
 .../diagnostics/tests/inner/kt5854.fir.kt     |  11 +
 .../diagnostics/tests/inner/kt6026.fir.kt     |   8 +
 .../diagnostics/tests/inner/localClass.fir.kt |  18 +
 .../tests/inner/localClassInsideNested.fir.kt |  11 +
 .../tests/inner/localThisSuper.fir.kt         |  23 ++
 .../diagnostics/tests/inner/modality.fir.kt   |  17 +
 ...edClassAccessedViaInstanceReference.fir.kt |  53 +++
 .../inner/nestedClassExtendsOuter.fir.kt      |   8 +
 .../nestedClassExtendsOuterGeneric.fir.kt     |  12 +
 .../tests/inner/nestedClassInObject.fir.kt    |  16 +
 .../inner/nestedClassNotAllowed_after.fir.kt  |  26 ++
 .../inner/nestedClassNotAllowed_before.fir.kt |  26 ++
 .../tests/inner/nestedObject.fir.kt           |  12 +
 .../nestedVsInnerAccessOuterMember.fir.kt     |  27 ++
 .../tests/inner/outerGenericParam.fir.kt      |  13 +
 .../tests/inner/outerProtectedMember.fir.kt   |  13 +
 .../tests/inner/outerSuperClassMember.fir.kt  |   9 +
 .../classObjectOfNestedClass.fir.kt           |  14 +
 .../constructNestedClass.fir.kt               |  17 +
 .../dataLocalVariable.fir.kt                  |   5 +
 .../qualifiedExpression/enumConstant.fir.kt   |   7 +
 .../genericNestedClass.fir.kt                 |  10 +
 .../importNestedClass.fir.kt                  |  17 +
 .../nestedClassInPackage.fir.kt               |   8 +
 .../nestedEnumConstant.fir.kt                 |   9 +
 .../qualifiedExpression/nestedObjects.fir.kt  |   7 +
 .../qualifiedExpression/typePosition.fir.kt   |  11 +
 .../tests/inner/referenceToSelfInLocal.fir.kt |  30 ++
 .../inner/resolvePackageClassInObjects.fir.kt |   9 +
 .../inner/selfAnnotationForClassObject.fir.kt |   9 +
 .../diagnostics/tests/inner/traits.fir.kt     |  11 +
 .../diagnostics/tests/inner/visibility.fir.kt |  34 ++
 .../tests/j+k/GenericsInSupertypes.fir.kt     |  49 +++
 .../tests/j+k/InheritedGenericFunction.fir.kt |  30 ++
 .../tests/j+k/InnerClassFromJava.fir.kt       |  16 +
 .../tests/j+k/KJKInheritance.fir.kt           |  18 +
 .../tests/j+k/KJKInheritanceGeneric.fir.kt    |  17 +
 .../tests/j+k/OverrideVararg.fir.kt           |  12 +
 .../diagnostics/tests/j+k/Simple.fir.kt       |  11 +
 .../j+k/StaticMembersFromSuperclasses.fir.kt  |  16 +
 ...ntsNullability-NotNull-SpecialTypes.fir.kt |  23 ++
 ...umentsNullability-NotNull-UserTypes.fir.kt |  23 ++
 ...peArgumentsNullability-SpecialTypes.fir.kt |  20 +
 ...rtypeArgumentsNullability-UserTypes.fir.kt |  20 +
 .../tests/j+k/UnboxingNulls.fir.kt            |  13 +
 .../j+k/accessClassObjectFromJava.fir.kt      |  10 +
 .../tests/j+k/ambiguousSamAdapters.fir.kt     |  17 +
 ...ionWithArgumentsMissingDependencies.fir.kt |  12 +
 .../tests/j+k/annotationsInheritance.fir.kt   |  19 +
 .../tests/j+k/arrayOfStarParametrized.fir.kt  |  14 +
 .../j+k/brokenCode/classDuplicates.fir.kt     |  13 +
 .../j+k/brokenCode/fieldDuplicates.fir.kt     |  13 +
 ...callableReferencesStaticMemberClash.fir.kt |  16 +
 .../canDeclareIfSamAdapterIsInherited.fir.kt  |  11 +
 .../j+k/collectionOverrides/charBuffer.fir.kt |  22 ++
 .../collectionStringImpl.fir.kt               |  85 ++++
 .../commonCollections.fir.kt                  |  28 ++
 .../j+k/collectionOverrides/contains.fir.kt   |  66 ++++
 .../collectionOverrides/containsAll.fir.kt    |  56 +++
 .../containsAndOverload.fir.kt                |  24 ++
 .../getCharSequence.fir.kt                    |  30 ++
 .../irrelevantCharAtAbstract.fir.kt           |  19 +
 .../irrelevantImplCharSequence.fir.kt         |  25 ++
 .../irrelevantImplCharSequenceKotlin.fir.kt   |  28 ++
 .../irrelevantImplMutableList.fir.kt          | 119 ++++++
 .../irrelevantImplMutableListKotlin.fir.kt    | 106 +++++
 .../irrelevantMapGetAbstract.fir.kt           |  19 +
 .../collectionOverrides/mapGetOverride.fir.kt |  14 +
 .../overridesBuiltinNoMagic.fir.kt            | 163 ++++++++
 .../j+k/collectionOverrides/removeAt.fir.kt   |  23 ++
 .../collectionOverrides/removeAtInt.fir.kt    |  23 ++
 .../sizeFromKotlinOverriddenInJava.fir.kt     |  13 +
 .../tests/j+k/collectorInference.fir.kt       |  14 +
 .../j+k/computeIfAbsentConcurrent.fir.kt      |  22 ++
 .../tests/j+k/contravariantIterable.fir.kt    |  20 +
 .../tests/j+k/defaultMethods.fir.kt           | 166 ++++++++
 .../defaultMethodsIndirectInheritance.fir.kt  |  79 ++++
 .../tests/j+k/defaultMethods_warning.fir.kt   | 168 ++++++++
 .../j+k/deprecations/forFakeOverrides.fir.kt  |  36 ++
 .../j+k/deprecations/forMixedOverride.fir.kt  |  27 ++
 .../j+k/deprecations/forOverrides.fir.kt      |  23 ++
 .../tests/j+k/differentFilename.fir.kt        |  26 ++
 .../tests/j+k/enumGetOrdinal.fir.kt           |  12 +
 .../tests/j+k/exceptionMessage.fir.kt         |  20 +
 .../tests/j+k/fieldOverridesField.fir.kt      |  17 +
 .../fieldOverridesFieldOfDifferentType.fir.kt |  19 +
 .../tests/j+k/fieldOverridesNothing.fir.kt    |  19 +
 .../tests/j+k/finalCollectionSize.fir.kt      |  12 +
 .../tests/j+k/flexibleNothing.fir.kt          |  19 +
 ...ssTypeParameterInferredFromArgument.fir.kt |  17 +
 .../j+k/genericConstructor/innerClass.fir.kt  |  18 +
 .../noClassTypeParameters.fir.kt              |  18 +
 .../noClassTypeParametersInvParameter.fir.kt  |  21 +
 .../j+k/genericConstructor/recursive.fir.kt   |  12 +
 .../j+k/genericConstructor/selfTypes.fir.kt   |  19 +
 .../j+k/genericConstructor/superCall.fir.kt   |  18 +
 .../superCallImpossibleToInfer.fir.kt         |  21 +
 .../withClassTypeParameters.fir.kt            |  19 +
 ...enericConstructorWithMultipleBounds.fir.kt |  18 +
 .../j+k/inheritAbstractSamAdapter.fir.kt      |  18 +
 ...nheritanceStaticMethodFromInterface.fir.kt |  32 ++
 .../tests/j+k/innerNestedClassFromJava.fir.kt |  32 ++
 ...isiblePackagePrivateInheritedMember.fir.kt |  23 ++
 .../tests/j+k/javaStaticImport.fir.kt         |  37 ++
 .../diagnostics/tests/j+k/kt1402.fir.kt       |  26 ++
 .../diagnostics/tests/j+k/kt1431.fir.kt       |  17 +
 .../j+k/kt1730_implementCharSequence.fir.kt   |  24 ++
 .../diagnostics/tests/j+k/kt2152.fir.kt       |  10 +
 .../diagnostics/tests/j+k/kt2394.fir.kt       |  15 +
 .../diagnostics/tests/j+k/kt2606.fir.kt       |  11 +
 .../diagnostics/tests/j+k/kt2619.fir.kt       |  15 +
 .../diagnostics/tests/j+k/kt2641.fir.kt       |  18 +
 .../diagnostics/tests/j+k/kt2890.fir.kt       |  20 +
 .../diagnostics/tests/j+k/kt3307.fir.kt       |  21 +
 .../diagnostics/tests/j+k/kt3311.fir.kt       |  19 +
 .../tests/j+k/kt6720_abstractProperty.fir.kt  |  18 +
 .../diagnostics/tests/j+k/kt7523.fir.kt       |  14 +
 .../diagnostics/tests/j+k/matchers.fir.kt     |  18 +
 .../tests/j+k/mutableIterator.fir.kt          |  29 ++
 .../tests/j+k/nullForOptionalOrElse.fir.kt    |   9 +
 .../tests/j+k/overrideRawType.fir.kt          |  15 +
 .../overrideWithSamAndTypeParameter.fir.kt    |  22 ++
 .../packagePrivateClassStaticMember.fir.kt    |  17 +
 .../tests/j+k/packageVisibility.fir.kt        |  44 +++
 .../j+k/primitiveOverrides/kt11140.fir.kt     |  24 ++
 .../notNullAnnotated.fir.kt                   |  22 ++
 .../primitiveOverrides/specializedMap.fir.kt  | 113 ++++++
 .../inlineClassErasedToPrimitiveInt.fir.kt    |  29 ++
 .../j+k/privateFieldOverridesNothing.fir.kt   |  19 +
 .../j+k/privateNestedClassStaticMember.fir.kt |  18 +
 .../tests/j+k/properties/interface.fir.kt     |  32 ++
 .../tests/j+k/properties/isName.fir.kt        |  27 ++
 .../tests/j+k/properties/val.fir.kt           |  25 ++
 .../tests/j+k/properties/var.fir.kt           |  42 ++
 .../j+k/protectedStaticSamePackage.fir.kt     |  20 +
 .../recursionWithJavaSyntheticProperty.fir.kt |  12 +
 .../tests/j+k/recursiveRawUpperBound.fir.kt   |  13 +
 .../tests/j+k/recursiveRawUpperBound2.fir.kt  |   8 +
 .../tests/j+k/recursiveRawUpperBound3.fir.kt  |   8 +
 .../j+k/sam/enhancedSamConstructor.fir.kt     |  28 ++
 .../fakeOverrideFunctionForStaticSam.fir.kt   |  20 +
 .../tests/j+k/sam/inheritedStaticSam.fir.kt   |  13 +
 ...privateCandidatesWithWrongArguments.fir.kt |  21 +
 .../j+k/sam/recursiveSamsAndInvoke.fir.kt     |  28 ++
 .../tests/j+k/sam/samOnTypeParameter.fir.kt   |  17 +
 .../sam/staticSamFromImportWithStar.fir.kt    |  17 +
 .../sam/staticSamWithExplicitImport.fir.kt    |  17 +
 .../j+k/sam/typeInferenceOnSamAdapters.fir.kt |  19 +
 .../tests/j+k/sam/withDefaultMethods.fir.kt   |  22 ++
 .../genericInReturnType.fir.kt                |  53 +++
 .../genericInValueParameter.fir.kt            |  32 ++
 .../genericSuperWildcard.fir.kt               |  25 ++
 ...AdapterBecuaseOfRecursiveUpperBound.fir.kt |  28 ++
 .../starProjectionComplexUpperBound.fir.kt    |  33 ++
 .../j+k/samInConstructorWithGenerics.fir.kt   |  23 ++
 .../tests/j+k/samWithConsumer.fir.kt          |  23 ++
 .../tests/j+k/selectMoreSpecific.fir.kt       |  16 +
 .../diagnostics/tests/j+k/serializable.fir.kt |  60 +++
 .../j+k/shadowingPrimitiveStaticField.fir.kt  |  24 ++
 .../signatureAnnotations/defaultEnum.fir.kt   |  67 ++++
 .../defaultLongLiteral.fir.kt                 |  49 +++
 .../signatureAnnotations/defaultNull.fir.kt   |  31 ++
 .../defaultNullAndParameter.fir.kt            |  57 +++
 .../defaultParameter.fir.kt                   |  45 +++
 .../emptyParameterName.fir.kt                 |  27 ++
 .../notNullVarargOverride.fir.kt              |  22 ++
 .../nullableVarargOverride.fir.kt             |  22 ++
 .../overridesDefaultValue.fir.kt              | 100 +++++
 .../overridesParameterName.fir.kt             |  98 +++++
 .../reorderedParameterNames.fir.kt            |  17 +
 .../sameParameterName.fir.kt                  |  17 +
 .../specialCharsParameterName.fir.kt          |  24 ++
 .../stableParameterName.fir.kt                |  20 +
 .../staticMethodWithDefaultValue.fir.kt       |  17 +
 .../tests/j+k/specialBridges.fir.kt           |   7 +
 .../hashtableInheritance.fir.kt               |   6 +
 .../specialBuiltIns/securityProvider.fir.kt   |   5 +
 .../tests/j+k/staticMethodInClass.fir.kt      |  16 +
 .../tests/j+k/traitDefaultCall.fir.kt         |  41 ++
 .../j+k/typeAliasWithSamConstructor.fir.kt    |  18 +
 .../tests/j+k/types/arrayList.fir.kt          |  15 +
 .../tests/j+k/types/returnCollection.fir.kt   |  13 +
 .../shapeMismatchInCovariantPosition.fir.kt   |  19 +
 ...eMismatchInCovariantPositionGeneric.fir.kt |  19 +
 .../tests/j+k/types/typeParameter.fir.kt      |  11 +
 .../tests/j+k/wrongVarianceInJava.fir.kt      |  24 ++
 ...stractBaseClassMemberNotImplemented.fir.kt |   9 +
 .../java8Overrides/abstractVsAbstract.fir.kt  |  13 +
 .../java8Overrides/defaultVsAbstract.fir.kt   |  13 +
 .../java8Overrides/hidingMethodOfAny.fir.kt   |   5 +
 .../implementingMethodOfAny.fir.kt            |   9 +
 .../java8Overrides/notAMethodOfAny.fir.kt     |   3 +
 .../overridingMethodOfAnyChain.fir.kt         |  13 +
 .../overridingMethodOfAnyDiamond.fir.kt       |  11 +
 .../singleRelevantDefault.fir.kt              |   9 +
 .../testData/diagnostics/tests/kt13401.fir.kt |  18 +
 .../testData/diagnostics/tests/kt310.fir.kt   |   5 +
 .../testData/diagnostics/tests/kt435.fir.kt   |   7 +
 .../testData/diagnostics/tests/kt53.fir.kt    |   6 +
 .../automaticLabelFromInfixOperator.fir.kt    |  17 +
 .../diagnostics/tests/labels/kt1703.fir.kt    |  15 +
 .../diagnostics/tests/labels/kt361.fir.kt     |  11 +
 .../diagnostics/tests/labels/kt3920.fir.kt    |   9 +
 .../diagnostics/tests/labels/kt3988.fir.kt    |  21 +
 .../diagnostics/tests/labels/kt4247.fir.kt    |  11 +
 .../diagnostics/tests/labels/kt4586.fir.kt    |  17 +
 .../diagnostics/tests/labels/kt4603.fir.kt    |  12 +
 .../diagnostics/tests/labels/kt591.fir.kt     |  11 +
 ...elReferencesInsideObjectExpressions.fir.kt |  27 ++
 .../labels/labeledFunctionLiteral.fir.kt      |  17 +
 .../tests/labels/labelsMustBeNamed.fir.kt     |  36 ++
 .../local/inapplicableLateinitModifier.fir.kt |  18 +
 .../tests/lateinit/local/localLateinit.fir.kt |   7 +
 .../tests/lateinit/local/uninitialized.fir.kt |  24 ++
 .../lateinit/modifierApplicability.fir.kt     |  71 ++++
 .../modifierApplicability_lv12.fir.kt         |  71 ++++
 .../diagnostics/tests/lateinit/setter.fir.kt  |  22 ++
 .../tests/library/Collections.fir.kt          | 111 ++++++
 .../diagnostics/tests/library/kt828.fir.kt    |  12 +
 .../localClasses/localAnnotationClass.fir.kt  |   9 +
 .../localAnnotationClassError.fir.kt          |   9 +
 .../diagnostics/tests/localInterfaces.fir.kt  |  14 +
 .../tests/modifiers/IllegalModifiers.fir.kt   | 163 ++++++++
 .../tests/modifiers/NoLocalVisibility.fir.kt  |   6 +
 .../tests/modifiers/annotations.fir.kt        |  12 +
 .../modifiers/const/applicability.fir.kt      | 110 ++++++
 .../arrayInAnnotationArgumentType.fir.kt      |   3 +
 .../modifiers/const/constInteraction.fir.kt   |  18 +
 .../tests/modifiers/const/fromJava.fir.kt     |  26 ++
 .../modifiers/const/fromJavaSubclass.fir.kt   |  15 +
 .../tests/modifiers/const/kt12248.fir.kt      |  19 +
 .../tests/modifiers/const/kt15913.fir.kt      |  19 +
 .../const/noDivisionByZeroFeature.fir.kt      |  21 +
 .../tests/modifiers/const/types.fir.kt        |  17 +
 .../tests/modifiers/defaultModifier.fir.kt    |  55 +++
 .../incompatibleVarianceModifiers.fir.kt      |  23 ++
 .../tests/modifiers/inlineParameters.fir.kt   |  20 +
 .../modifiers/internalInInterface.fir.kt      |   7 +
 .../modifierOnParameterInFunctionType.fir.kt  |  52 +++
 .../tests/modifiers/openInInterface.fir.kt    |  10 +
 .../operatorInfix/LocalFunctions.fir.kt       |  39 ++
 .../operatorInfix/MemberFunctions.fir.kt      |  45 +++
 .../modifiers/operatorInfix/Simple.fir.kt     |  45 +++
 .../primaryConstructorMissingBrackets.fir.kt  |   2 +
 .../primaryConstructorMissingKeyword.fir.kt   |   9 +
 .../tests/modifiers/privateInInterface.fir.kt |  12 +
 .../tests/modifiers/protected.fir.kt          |  21 +
 .../tests/modifiers/redundantTargets.fir.kt   |  10 +
 .../tests/modifiers/repeatedModifiers.fir.kt  |  41 ++
 .../collectionMethodStub.fir.kt               |  21 +
 .../differentGenericArguments.fir.kt          |  29 ++
 .../differentGenericArgumentsReversed.fir.kt  |  29 ++
 .../duplicateClass/duplicateClass.fir.kt      |  32 ++
 .../duplicateNestedClasses.fir.kt             |  68 ++++
 .../duplicateClass/duplicateSuperClass.fir.kt |  30 ++
 .../genericArgumentNumberMismatch.fir.kt      |  30 ++
 .../duplicateClass/genericSuperClass.fir.kt   |  42 ++
 .../inTheSameModuleWithUsage.fir.kt           |  23 ++
 ...SameModuleWithUsageNoTypeAnnotation.fir.kt |  23 ++
 .../multimodule/duplicateClass/members.fir.kt |  38 ++
 .../sameClassNameDifferentPackages.fir.kt     |  22 ++
 .../sameGenericArguments.fir.kt               |  29 ++
 .../classGenericsInParams.fir.kt              |  36 ++
 .../classGenericsInParamsBoundMismatch.fir.kt |  38 ++
 .../classGenericsInParamsIndexMismatch.fir.kt |  34 ++
 .../classGenericsInParamsNameMismatch.fir.kt  |  36 ++
 .../classGenericsInReturnType.fir.kt          |  36 ++
 ...sVsFunctionGenericsInParamsMismatch.fir.kt |  37 ++
 .../covariantReturnTypes.fir.kt               |  36 ++
 .../differenceInParamNames.fir.kt             |  36 ++
 .../differentGenericsInParams.fir.kt          |  43 ++
 .../differentNumberOfParams.fir.kt            |  34 ++
 .../differentReturnTypes.fir.kt               |  36 ++
 .../duplicateMethod/extensionMatch.fir.kt     |  36 ++
 .../functionGenericsInParams.fir.kt           |  42 ++
 ...ctionGenericsInParamsBoundsMismatch.fir.kt |  40 ++
 .../functionGenericsInParamsEqNull.fir.kt     |  52 +++
 .../functionGenericsInParamsNotIs.fir.kt      |  40 ++
 .../functionGenericsInParamsReturnFooT.fir.kt |  44 +++
 .../functionGenericsInParamsReturnT.fir.kt    |  40 ++
 .../incompleteCodeNoNoneApplicable.fir.kt     |  20 +
 .../duplicateMethod/noGenericsInParams.fir.kt |  35 ++
 .../duplicateMethod/noParams.fir.kt           |  36 ++
 .../sameGenericsInParams.fir.kt               |  43 ++
 .../simpleWithInheritance.fir.kt              |  38 ++
 .../duplicateMethod/sinceKotlin.fir.kt        |  34 ++
 .../substitutedGenericInParams.fir.kt         |  34 ++
 .../differentSuperTraits.fir.kt               |  31 ++
 .../duplicateSuper/sameSuperTrait.fir.kt      |  26 ++
 .../sameSuperTraitDifferentBounds.fir.kt      |  29 ++
 .../sameSuperTraitGenerics.fir.kt             |  26 ++
 .../deprecatedHiddenImportPriority.fir.kt     |  37 ++
 .../deprecatedHiddenMultipleClasses.fir.kt    |  46 +++
 .../sinceKotlinImportPriority.fir.kt          |  38 ++
 .../sinceKotlinMultipleClasses.fir.kt         |  47 +++
 .../tests/multimodule/internal.fir.kt         |  35 ++
 .../tests/multimodule/kt14249.fir.kt          |  20 +
 .../tests/multimodule/packagePrivate.fir.kt   |  19 +
 .../multimodule/publishedApiInternal.fir.kt   |  56 +++
 .../multimodule/redundantElseInWhen.fir.kt    |  45 +++
 .../tests/multimodule/varargConflict.fir.kt   |  26 ++
 .../annotationArgumentEquality.fir.kt         |  89 +++++
 .../defaultArguments/annotations.fir.kt       |  33 ++
 .../annotationsViaActualTypeAlias.fir.kt      |  64 +++
 .../annotationsViaActualTypeAlias2.fir.kt     |  79 ++++
 .../defaultArguments/constructor.fir.kt       |  23 ++
 .../expectedDeclaresDefaultArguments.fir.kt   |  41 ++
 .../expectedInheritsDefaultArguments.fir.kt   |  37 ++
 .../expectedVsNonExpectedWithDefaults.fir.kt  |  17 +
 .../multiplatform/deprecated/header.fir.kt    |  30 ++
 .../enum/additionalEntriesInImpl.fir.kt       |  10 +
 .../enum/constructorInHeaderEnum.fir.kt       |  15 +
 .../enum/differentEntryOrder.fir.kt           |  10 +
 .../enum/enumEntryWithBody.fir.kt             |  11 +
 .../tests/multiplatform/enum/javaEnum.fir.kt  |  32 ++
 .../multiplatform/enum/simpleEnum.fir.kt      |  16 +
 .../functionTypeParameterBounds.fir.kt        |  12 +
 .../generic/genericMemberBounds.fir.kt        |  25 ++
 .../generic/membersInGenericClass.fir.kt      |  18 +
 ...erBoundsDifferentOrderActualMissing.fir.kt |  13 +
 ...faultValuesInAnnotationViaTypealias.fir.kt |  48 +++
 ...ctualClassWithDifferentConstructors.fir.kt |  55 +++
 .../headerClass/actualMissing.fir.kt          |  14 +
 .../baseExpectClassWithoutConstructor.fir.kt  |  13 +
 .../headerClass/classKinds.fir.kt             |  26 ++
 ...ideMethodsFromInterfaceInCommonCode.fir.kt |  28 ++
 ...pectClassWithExplicitAbstractMember.fir.kt |  23 ++
 .../expectClassWithoutConstructor.fir.kt      |  25 ++
 ...larationWithStrongIncompatibilities.fir.kt |  33 ++
 ...eclarationWithWeakIncompatibilities.fir.kt |  28 ++
 .../headerClass/expectFinalActualOpen.fir.kt  |  27 ++
 .../explicitConstructorDelegation.fir.kt      |  14 +
 ...tendExpectedClassWithAbstractMember.fir.kt |  62 +++
 ...lassWithoutExplicitOverrideOfMethod.fir.kt |  36 ++
 .../headerClass/extraHeaderOnMembers.fir.kt   |  14 +
 .../functionAndPropertyWithSameName.fir.kt    |  15 +
 .../genericClassImplTypeAlias.fir.kt          |  31 ++
 .../headerClass/headerClassMember.fir.kt      |  24 ++
 .../headerClassWithFunctionBody.fir.kt        |  27 ++
 .../headerClass/implDataClass.fir.kt          |  32 ++
 .../headerClass/implOpenClass.fir.kt          |  18 +
 ...nheritanceByDelegationInExpectClass.fir.kt |  10 +
 .../headerClass/memberPropertyKinds.fir.kt    |  31 ++
 ...CheckForExplicitAndImplicitOverride.fir.kt |  35 ++
 .../morePermissiveVisibilityOnActual.fir.kt   |  39 ++
 ...ssiveVisibilityOnActualViaTypeAlias.fir.kt |  22 ++
 .../headerClass/nestedClasses.fir.kt          |  58 +++
 .../nestedClassesWithErrors.fir.kt            |  46 +++
 .../headerClass/noImplKeywordOnMember.fir.kt  |  14 +
 .../headerClass/privateMembers.fir.kt         |  22 ++
 .../headerClass/simpleHeaderClass.fir.kt      |  12 +
 .../headerClass/smartCastOnExpectClass.fir.kt |  13 +
 .../headerClass/superClass.fir.kt             |  23 ++
 .../headerFunInNonHeaderClass.fir.kt          |  10 +
 .../multiplatform/implDelegatedMember.fir.kt  |  19 +
 .../tests/multiplatform/implDynamic.fir.kt    |  29 ++
 .../multiplatform/implFakeOverride.fir.kt     |  16 +
 .../tests/multiplatform/incompatibles.fir.kt  |  13 +
 .../expectActualInlineClass.fir.kt            |  28 ++
 .../multiplatform/java/flexibleTypes.fir.kt   |  32 ++
 .../multiplatform/java/parameterNames.fir.kt  |  18 +
 .../modifierApplicability.fir.kt              |  35 ++
 .../tests/multiplatform/namedArguments.fir.kt |  37 ++
 .../privateTopLevelDeclarations.fir.kt        |  18 +
 .../multiplatform/sealedTypeAlias.fir.kt      |  17 +
 .../sealedTypeAliasTopLevel.fir.kt            |  16 +
 .../topLevelFun/callHeaderFun.fir.kt          |  25 ++
 .../callableReferenceOnExpectFun.fir.kt       |  21 +
 .../conflictingHeaderDeclarations.fir.kt      |   8 +
 .../conflictingImplDeclarations.fir.kt        |  17 +
 .../topLevelFun/functionModifiers.fir.kt      |  19 +
 .../headerAndImplInDIfferentPackages.fir.kt   |  18 +
 .../headerDeclarationWithBody.fir.kt          |   9 +
 .../topLevelFun/headerWithoutImpl.fir.kt      |   5 +
 .../implDeclarationWithoutBody.fir.kt         |  12 +
 .../topLevelFun/implWithoutHeader.fir.kt      |   5 +
 .../topLevelFun/inlineFun.fir.kt              |  18 +
 .../topLevelFun/simpleHeaderFun.fir.kt        |  12 +
 .../valueParameterModifiers.fir.kt            |  27 ++
 .../differentKindsOfProperties.fir.kt         |  40 ++
 .../topLevelProperty/simpleHeaderVar.fir.kt   |  12 +
 .../allowForJavaAnnotation.fir.kt             |  12 +
 .../ambiguousNamedArguments1.fir.kt           |  27 ++
 .../ambiguousNamedArguments2.fir.kt           |  24 ++
 ...mbiguousNamedArgumentsWithGenerics1.fir.kt |  15 +
 ...mbiguousNamedArgumentsWithGenerics2.fir.kt |  15 +
 ...mbiguousNamedArgumentsWithGenerics3.fir.kt |  15 +
 .../disallowForJavaConstructor.fir.kt         |   9 +
 .../disallowForJavaMethods.fir.kt             |  27 ++
 .../disallowForSamAdapterConstructor.fir.kt   |  17 +
 .../disallowForSamAdapterFunction.fir.kt      |  17 +
 .../mixedNamedPosition/defaults.fir.kt        |  28 ++
 .../mixedNamedPosition/disabledFeature.fir.kt |  20 +
 .../mixedNamedPosition/oldInference.fir.kt    |  20 +
 .../mixedNamedPosition/simple.fir.kt          |  20 +
 .../mixedNamedPosition/varargs.fir.kt         |  57 +++
 .../namedArgumentsAndDefaultValues.fir.kt     |  27 ++
 .../namedArgumentsInOverloads.fir.kt          |  14 +
 .../namedArgumentsInOverrides.fir.kt          |  22 ++
 .../AssertNotNull.fir.kt                      |  39 ++
 .../InfixCallNullability.fir.kt               |  41 ++
 .../NullableNothingIsExactlyNull.fir.kt       |   8 +
 .../PreferExtensionsOnNullableReceiver.fir.kt |   9 +
 .../QualifiedExpressionNullability.fir.kt     |  30 ++
 .../ReceiverNullability.fir.kt                |  44 +++
 .../SenselessNullInWhen.fir.kt                |  10 +
 .../dataFlowInfoAfterExclExcl.fir.kt          |   8 +
 .../equalityUnderNotNullCheck.fir.kt          |   5 +
 .../funcLiteralArgsInsideAmbiguity.fir.kt     |  14 +
 ...LiteralArgsInsideUnresolvedFunction.fir.kt |  10 +
 .../nullabilityAndSmartCasts/kt1270.fir.kt    |  13 +
 .../nullabilityAndSmartCasts/kt1680.fir.kt    |  14 +
 .../nullabilityAndSmartCasts/kt1778.fir.kt    |  12 +
 .../nullabilityAndSmartCasts/kt2109.fir.kt    |  20 +
 .../nullabilityAndSmartCasts/kt2125.fir.kt    |  12 +
 .../nullabilityAndSmartCasts/kt2146.fir.kt    |  55 +++
 .../nullabilityAndSmartCasts/kt2164.fir.kt    |  39 ++
 .../nullabilityAndSmartCasts/kt2176.fir.kt    |  29 ++
 .../nullabilityAndSmartCasts/kt2195.fir.kt    |   8 +
 .../nullabilityAndSmartCasts/kt2212.fir.kt    |   8 +
 .../nullabilityAndSmartCasts/kt2216.fir.kt    |  22 ++
 .../nullabilityAndSmartCasts/kt2223.fir.kt    |   8 +
 .../nullabilityAndSmartCasts/kt2234.fir.kt    |  23 ++
 .../nullabilityAndSmartCasts/kt2336.fir.kt    |  11 +
 .../nullabilityAndSmartCasts/kt244.fir.kt     |  33 ++
 .../nullabilityAndSmartCasts/kt30734.fir.kt   |  16 +
 .../nullabilityAndSmartCasts/kt362.fir.kt     |  29 ++
 .../noSenselessNullOnNullableType.fir.kt      |  21 +
 ...ecessaryNotNullAssertionOnErrorType.fir.kt |   7 +
 .../notnullTypesFromJavaWithSmartcast.fir.kt  |  20 +
 ...ullableReceiverWithOverloadedMethod.fir.kt |  29 ++
 ...sComparisonWithNullOnTypeParameters.fir.kt |  16 +
 .../smartCastReceiverWithGenerics.fir.kt      |   7 +
 .../smartCastsAndBooleanExpressions.fir.kt    |   8 +
 .../unnecessaryNotNullAssertion.fir.kt        |  24 ++
 ...rtcastWhenOpenGetterWithOverloading.fir.kt |  15 +
 ...leSmartcastWithOverloadedExtensions.fir.kt |  14 +
 .../baseWithNullableUpperBound.fir.kt         |  13 +
 .../tests/nullableTypes/elvisOnUnit.fir.kt    |  11 +
 ...lAssertOnTypeWithNullableUpperBound.fir.kt |  15 +
 .../nullableArgumentForIn.fir.kt              |   3 +
 ...eArgumentToNonNullParameterPlatform.fir.kt |  18 +
 ...bleArgumentToNonNullParameterSimple.fir.kt |  13 +
 .../nullableTypes/redundantNullable.fir.kt    |   9 +
 .../redundantNullableInSupertype.fir.kt       |   9 +
 .../nullableTypes/safeAccessOnUnit.fir.kt     |   7 +
 ...afeCallOnTypeWithNullableUpperBound.fir.kt |  14 +
 .../nullableTypes/safeCallWithInvoke.fir.kt   |  12 +
 .../tests/nullableTypes/uselessElvis.fir.kt   |  48 +++
 .../numbers/characterIsNotANumber.fir.kt      |  12 +
 .../numbers/doublesInSimpleConstraints.fir.kt |  23 ++
 .../tests/numbers/intValuesOutOfRange.fir.kt  |  17 +
 .../numberAsUnionAndIntersection.fir.kt       |  22 ++
 .../numbers/numbersInSimpleConstraints.fir.kt |  78 ++++
 .../diagnostics/tests/objects/Objects.fir.kt  |  29 ++
 .../tests/objects/ObjectsInheritance.fir.kt   |   5 +
 .../tests/objects/ObjectsLocal.fir.kt         |  25 ++
 .../tests/objects/ObjectsNested.fir.kt        |  29 ++
 .../tests/objects/OpenInObject.fir.kt         |   9 +
 .../tests/objects/invokeOnInnerObject.fir.kt  |  12 +
 .../kt21515/annotationConstructor.fir.kt      |  13 +
 ...ReferenceComplexCasesWithImportsOld.fir.kt |  74 ++++
 ...cesComplexCasesWithQualificationOld.fir.kt |  69 ++++
 .../kt21515/callableReferencesNew.fir.kt      | 142 +++++++
 .../kt21515/callableReferencesOld.fir.kt      | 142 +++++++
 .../callableReferencesOldComplexCases.fir.kt  |  69 ++++
 ...lableReferencesWithQualificationNew.fir.kt | 142 +++++++
 ...lableReferencesWithQualificationOld.fir.kt | 142 +++++++
 .../classifierFromCompanionObjectNew.fir.kt   |  99 +++++
 .../classifierFromCompanionObjectOld.fir.kt   |  98 +++++
 ...CompanionObjectWithQualificationNew.fir.kt |  99 +++++
 ...CompanionObjectWithQualificationOld.fir.kt |  98 +++++
 .../classifierIsVisibleByTwoPaths.fir.kt      |  17 +
 .../kt21515/inheritedFromDeprecatedNew.fir.kt | 100 +++++
 .../kt21515/inheritedFromDeprecatedOld.fir.kt | 100 +++++
 ...dFromDeprecatedWithQualificationNew.fir.kt | 100 +++++
 ...dFromDeprecatedWithQualificationOld.fir.kt | 100 +++++
 .../objects/kt21515/staticsFromJavaNew.fir.kt |  48 +++
 .../objects/kt21515/staticsFromJavaOld.fir.kt |  48 +++
 ...staticsFromJavaWithQualificationNew.fir.kt |  53 +++
 ...staticsFromJavaWithQualificationOld.fir.kt |  53 +++
 .../useDeprecatedConstructorNew.fir.kt        | 100 +++++
 .../useDeprecatedConstructorOld.fir.kt        |  99 +++++
 ...atedConstructorWithQualificationNew.fir.kt | 100 +++++
 ...atedConstructorWithQualificationOld.fir.kt | 100 +++++
 .../diagnostics/tests/objects/kt2240.fir.kt   |  13 +
 .../diagnostics/tests/objects/kt5527.fir.kt   |  20 +
 .../objects/localObjectInsideObject.fir.kt    |  11 +
 .../tests/objects/localObjects.fir.kt         |  15 +
 .../nestedClassInAnonymousObject.fir.kt       |  11 +
 .../tests/objects/objectInsideFun.fir.kt      |  11 +
 ...objectLiteralExpressionTypeMismatch.fir.kt |   9 +
 .../tests/objects/upperBoundViolated.fir.kt   |   9 +
 ...recatedModAssignOperatorConventions.fir.kt |  43 ++
 .../DeprecatedModOperatorConventions.fir.kt   |  37 ++
 .../deprecatedModConvention.fir.kt            |  38 ++
 .../doNotResolveToInapplicableRem.fir.kt      |  14 +
 .../operatorRem/errorOnExplicitModCall.fir.kt |   3 +
 .../forbiddenModOperatorConvention.fir.kt     |  32 ++
 .../tests/operatorRem/modWithRemAssign.fir.kt |  17 +
 ...precatedModConventionWithoutFeature.fir.kt |  38 ++
 .../operatorRem/noOperatorRemFeature.fir.kt   |  36 ++
 ...gForModFromBuiltinsWhenApi1_0_after.fir.kt |  48 +++
 ...ForModFromBuiltinsWhenApi1_0_before.fir.kt |  48 +++
 .../operatorRem/numberRemConversions.fir.kt   |  15 +
 .../tests/operatorRem/operatorRem.fir.kt      |  15 +
 .../preferRemAsExtentionOverMod.fir.kt        |  13 +
 .../preferRemAsMemberOverMod.fir.kt           |  13 +
 ...preferRemFromCompanionObjectOverRem.fir.kt |  16 +
 .../preferRemOverModInLocalFunctions.fir.kt   |  30 ++
 .../preferRemWithImplicitReceivers.fir.kt     |  20 +
 .../prefereRemAsExtensionOverMemberMod.fir.kt |  15 +
 .../remAndRemAssignAmbiguity.fir.kt           |  12 +
 .../operatorRem/remWithModAndModAssign.fir.kt |  17 +
 .../tests/operatorRem/remWithModAssign.fir.kt |  12 +
 .../resolveModIfRemIsHidden.fir.kt            |  15 +
 ...esolveToModWhenNoOperatorRemFeature.fir.kt |  39 ++
 .../warningOnExplicitModCall1_1.fir.kt        |   5 +
 .../warningOnExplicitModCall1_2.fir.kt        |   5 +
 .../AssignOperatorAmbiguity.fir.kt            |  17 +
 .../AssignmentOperations.fir.kt               |  40 ++
 .../InconsistentGetSet.fir.kt                 |  45 +++
 .../IteratorAmbiguity.fir.kt                  |  27 ++
 ...assignmentOperationsCheckReturnType.fir.kt |  48 +++
 .../compareToNullable.fir.kt                  |  12 +
 .../tests/operatorsOverloading/kt1028.fir.kt  |  35 ++
 .../tests/operatorsOverloading/kt11300.fir.kt |  13 +
 .../tests/operatorsOverloading/kt13330.fir.kt |   4 +
 .../tests/operatorsOverloading/kt13349.fir.kt |   7 +
 .../tests/operatorsOverloading/kt3450.fir.kt  |  23 ++
 .../plusAssignOnArray.fir.kt                  |  20 +
 .../plusAssignOnLocal.fir.kt                  |  13 +
 .../plusAssignOnProperty.fir.kt               |  19 +
 ...nflictingOlverloadsGenericFunctions.fir.kt |  34 ++
 ...OverloadsFunsDifferentReturnInClass.fir.kt |   6 +
 ...erloadsFunsDifferentReturnInPackage.fir.kt |   7 +
 ...gOverloadsIdenticalExtFunsInPackage.fir.kt |   5 +
 ...ictingOverloadsIdenticalFunsInClass.fir.kt |   7 +
 ...tingOverloadsIdenticalFunsTPInClass.fir.kt |   4 +
 ...ictingOverloadsIdenticalValsInClass.fir.kt |   4 +
 ...ngOverloadsValsDifferentTypeInClass.fir.kt |   4 +
 .../overload/ConstructorVsFunOverload.fir.kt  |  29 ++
 .../overload/EmptyArgumentListInLambda.fir.kt |   8 +
 .../overload/ExtFunDifferentReceiver.fir.kt   |   3 +
 .../FunNoConflictInDifferentPackages.fir.kt   |  13 +
 .../tests/overload/LocalFunctions.fir.kt      | 213 ++++++++++
 .../overload/OverloadFunRegularAndExt.fir.kt  |   7 +
 .../overload/OverloadVarAndFunInClass.fir.kt  |   4 +
 .../overload/SyntheticAndNotSynthetic.fir.kt  |   7 +
 .../TypeParameterMultipleBounds.fir.kt        |  15 +
 .../overload/UnsubstitutedJavaGenetics.fir.kt |  17 +
 .../tests/overload/defaultParameters.fir.kt   |  59 +++
 .../diagnostics/tests/overload/kt10939.fir.kt |  28 ++
 .../diagnostics/tests/overload/kt1998.fir.kt  |  14 +
 .../diagnostics/tests/overload/kt2493.fir.kt  |  20 +
 .../diagnostics/tests/overload/kt7068.fir.kt  |  17 +
 .../tests/overload/kt7068_2.fir.kt            |  17 +
 .../diagnostics/tests/overload/kt7440.fir.kt  |  17 +
 .../onlyPrivateOverloadsDiagnostic.fir.kt     |  12 +
 .../override/AbstractFunImplemented.fir.kt    |   7 +
 .../override/AbstractFunNotImplemented.fir.kt |   6 +
 .../override/AbstractValImplemented.fir.kt    |   7 +
 .../override/AbstractValNotImplemented.fir.kt |   6 +
 .../override/AbstractVarImplemented.fir.kt    |   7 +
 .../override/AbstractVarNotImplemented.fir.kt |   6 +
 .../override/AllPrivateFromSuperTypes.fir.kt  |  14 +
 .../override/ComplexValRedeclaration.fir.kt   |  10 +
 ...tingFunctionSignatureFromSuperclass.fir.kt |   7 +
 ...tingPropertySignatureFromSuperclass.fir.kt |   8 +
 .../DefaultParameterValueInOverride.fir.kt    |  13 +
 ...rrorsWhenInheritingFromOneTypeTwice.fir.kt |  15 +
 .../tests/override/Delegation.fir.kt          |  49 +++
 .../tests/override/DelegationFun.fir.kt       |   7 +
 .../tests/override/DelegationVal.fir.kt       |   7 +
 .../tests/override/DelegationVar.fir.kt       |   7 +
 .../tests/override/DuplicateMethod.fir.kt     |   8 +
 .../EqualityOfIntersectionTypes.fir.kt        |  15 +
 .../tests/override/ExtendFunctionClass.fir.kt |   9 +
 ...keOverrideAbstractAndNonAbstractFun.fir.kt |   9 +
 ...rrideDifferentDeclarationSignatures.fir.kt |  11 +
 .../override/FakeOverrideModality1.fir.kt     |  14 +
 .../override/FakeOverrideModality2.fir.kt     |  18 +
 .../override/FakeOverrideModality3.fir.kt     |  16 +
 .../tests/override/Generics.fir.kt            |  60 +++
 .../InvisiblePotentialOverride.fir.kt         |   7 +
 .../tests/override/MissingDelegate.fir.kt     |   3 +
 ...ltipleDefaultParametersInSupertypes.fir.kt |  15 +
 ...ultParametersInSupertypesNoOverride.fir.kt |  15 +
 ...ultipleDefaultsAndNamesInSupertypes.fir.kt |  14 +
 ...aultsInSupertypesNoExplicitOverride.fir.kt |  10 +
 .../tests/override/NonGenerics.fir.kt         |  50 +++
 .../override/ObjectDelegationManyImpl.fir.kt  |  13 +
 .../tests/override/OverrideWithErrors.fir.kt  |   9 +
 .../override/OverridingFinalMember.fir.kt     |   7 +
 ...es-DefaultValueFromOnlyOneSupertype.fir.kt |  11 +
 .../ParentInheritsManyImplementations.fir.kt  |  17 +
 .../override/PropertyInConstructor.fir.kt     |  11 +
 .../ProtectedAndPrivateFromSupertypes.fir.kt  |  17 +
 .../tests/override/SuspiciousCase1.fir.kt     |  12 +
 .../ToAbstractMembersFromSuper-kt1996.fir.kt  |  11 +
 .../covariantOverrides.fir.kt                 |  37 ++
 .../flexibleReturnType.fir.kt                 |  27 ++
 .../flexibleReturnTypeIn.fir.kt               |  61 +++
 .../flexibleReturnTypeList.fir.kt             |  43 ++
 .../genericWithUpperBound.fir.kt              |  56 +++
 .../clashesOnInheritance/kt13355.fir.kt       |  13 +
 .../kt13355viaJava.fir.kt                     |  47 +++
 .../clashesOnInheritance/kt9550.fir.kt        |  13 +
 .../returnTypeMismatch.fir.kt                 |  29 ++
 .../unrelatedInherited.fir.kt                 |  33 ++
 .../valTypeMismatch.fir.kt                    |  29 ++
 .../varTypeMismatch.fir.kt                    |  29 ++
 .../tests/override/fakeEquals.fir.kt          |   9 +
 .../diagnostics/tests/override/kt12358.fir.kt |   9 +
 .../diagnostics/tests/override/kt12467.fir.kt |  14 +
 .../diagnostics/tests/override/kt12482.fir.kt |  11 +
 .../diagnostics/tests/override/kt1862.fir.kt  |  11 +
 .../diagnostics/tests/override/kt2052.fir.kt  |  10 +
 .../diagnostics/tests/override/kt2491.fir.kt  |  11 +
 .../diagnostics/tests/override/kt4763.fir.kt  |  11 +
 .../tests/override/kt4763property.fir.kt      |  11 +
 .../diagnostics/tests/override/kt4785.fir.kt  |  11 +
 .../diagnostics/tests/override/kt6014.fir.kt  |  17 +
 .../diagnostics/tests/override/kt880.fir.kt   |  16 +
 .../diagnostics/tests/override/kt8990.fir.kt  |  11 +
 .../overrideMemberFromFinalClass.fir.kt       |  28 ++
 .../changeOnOverrideDiagnostic.fir.kt         |  13 +
 ...ifferentNamesInSupertypesDiagnostic.fir.kt |  15 +
 .../invokeInFunctionClass.fir.kt              |  27 ++
 .../parameterNames/jjkHierarchy.fir.kt        |  16 +
 .../parameterNames/kjkHierarchy.fir.kt        |  16 +
 .../kjkWithSeveralSupers.fir.kt               |  51 +++
 .../kotlinInheritsBothJavaAndKotlin.fir.kt    |  13 +
 .../parameterNames/kotlinInheritsJava.fir.kt  |  18 +
 .../classAndTwoInterfaceBounds.fir.kt         |  31 ++
 .../differentSetsOfBounds.fir.kt              |   7 +
 .../override/typeParameters/kt9850.fir.kt     |   8 +
 .../simpleVisitorTwoAccepts.fir.kt            |  10 +
 ...tationsOnNullableParenthesizedTypes.fir.kt |  29 ++
 .../annotationsOnParenthesizedTypes.fir.kt    |  31 ++
 .../splitModifierList.fir.kt                  |  16 +
 .../commonSupertype/collectionOrNull.fir.kt   |  19 +
 .../commonSupertype/inferenceWithBound.fir.kt |  41 ++
 .../commonSupertype/mixedElvis.fir.kt         |  13 +
 .../commonSupertype/mixedIf.fir.kt            |  21 +
 .../commonSupertype/recursiveGeneric.fir.kt   |  35 ++
 .../commonSupertype/stringOrNull.fir.kt       |  19 +
 .../commonSupertype/typeOfElvis.fir.kt        |  20 +
 .../commonSupertype/withNothing.fir.kt        |  27 ++
 .../delegateByComplexInheritance.fir.kt       |  15 +
 .../tests/platformTypes/dereference.fir.kt    |  30 ++
 .../tests/platformTypes/elvis.fir.kt          |  16 +
 .../explicitFlexibleNoPackage.fir.kt          |   8 +
 .../explicitFlexibleWithPackage.fir.kt        |   9 +
 .../listSuperType.fir.kt                      |  16 +
 .../genericVarianceViolation/rawTypes.fir.kt  |  14 +
 .../genericVarianceViolation/simple.fir.kt    |  67 ++++
 .../genericVarianceViolation/smartCast.fir.kt |  16 +
 .../strangeVariance.fir.kt                    |  18 +
 .../userDefinedOut.fir.kt                     |  17 +
 .../valueFromJava.fir.kt                      |  14 +
 .../genericVarianceViolation/wildcards.fir.kt |  49 +++
 .../platformTypes/getParentOfType.fir.kt      |  36 ++
 .../tests/platformTypes/inference.fir.kt      |  25 ++
 .../intVsIntegerAmbiguity.fir.kt              |  37 ++
 .../platformTypes/intersection/map.fir.kt     |  12 +
 .../tests/platformTypes/javaEmptyList.fir.kt  |  25 ++
 .../platformTypes/methodCall/entrySet.fir.kt  |  24 ++
 .../methodCall/genericsAndArrays.fir.kt       |  24 ++
 .../tests/platformTypes/methodCall/int.fir.kt |  16 +
 .../platformTypes/methodCall/intArray.fir.kt  |  16 +
 .../methodCall/javaCollectionToKotlin.fir.kt  |   9 +
 .../methodCall/javaToJava.fir.kt              |  20 +
 .../methodCall/javaToKotlin.fir.kt            |  18 +
 .../methodCall/kotlinCollectionToJava.fir.kt  |   7 +
 .../platformTypes/methodCall/kt27565.fir.kt   |  21 +
 .../platformTypes/methodCall/list.fir.kt      |  18 +
 .../methodCall/multipleExactBounds.fir.kt     |  21 +
 .../multipleExactBoundsNullable.fir.kt        |  39 ++
 .../methodCall/objectArray.fir.kt             |  23 ++
 .../methodCall/overloadingForSubclass.fir.kt  |  30 ++
 .../tests/platformTypes/methodCall/sam.fir.kt |  26 ++
 .../platformTypes/methodCall/singleton.fir.kt |  10 +
 .../platformTypes/methodCall/string.fir.kt    |  16 +
 .../platformTypes/methodCall/visitor.fir.kt   |  26 ++
 .../methodTypeParameterDefaultBound.fir.kt    |  25 ++
 .../noAnnotationInClassPath.fir.kt            |  17 +
 .../enhancementFromAnnotation.fir.kt          |  28 ++
 .../enhancementFromKotlin.fir.kt              |  28 ++
 .../methodTypeParameter.fir.kt                |  19 +
 .../noInheritanceReturnType.fir.kt            |  23 ++
 .../noInheritanceValueParameter.fir.kt        |  26 ++
 .../onTypeProjection.fir.kt                   |  19 +
 .../substitutionInSuperType.fir.kt            |  41 ++
 .../nullabilityWarnings/arithmetic.fir.kt     |  55 +++
 .../nullabilityWarnings/array.fir.kt          |  31 ++
 .../nullabilityWarnings/assignToVar.fir.kt    |  27 ++
 .../nullabilityWarnings/conditions.fir.kt     |  48 +++
 .../nullabilityWarnings/dataFlowInfo.fir.kt   |  32 ++
 .../defaultParameters.fir.kt                  |  28 ++
 .../delegatedProperties.fir.kt                |  23 ++
 .../nullabilityWarnings/delegation.fir.kt     |  19 +
 .../derefenceExtension.fir.kt                 |  45 +++
 .../derefenceMember.fir.kt                    |  40 ++
 .../nullabilityWarnings/elvis.fir.kt          |  67 ++++
 .../nullabilityWarnings/expectedType.fir.kt   |  32 ++
 .../nullabilityWarnings/for.fir.kt            |  28 ++
 .../functionArguments.fir.kt                  |  27 ++
 .../inferenceInConditionals.fir.kt            |  27 ++
 .../nullabilityWarnings/invoke.fir.kt         |  24 ++
 .../nullabilityWarnings/kt6829.fir.kt         |  24 ++
 .../multiDeclaration.fir.kt                   |  32 ++
 .../noWarningOnDoubleElvis.fir.kt             |   8 +
 .../notNullAfterSafeCall.fir.kt               |  16 +
 .../notNullAssertion.fir.kt                   |  40 ++
 .../notNullAssertionInCall.fir.kt             |  27 ++
 ...ullTypeMarkedWithNullableAnnotation.fir.kt |  22 ++
 .../nullabilityWarnings/passToJava.fir.kt     |  90 +++++
 .../nullabilityWarnings/primitiveArray.fir.kt |  31 ++
 .../nullabilityWarnings/safeCall.fir.kt       |  43 ++
 .../senselessComparisonEquals.fir.kt          |  42 ++
 .../senselessComparisonIdentityEquals.fir.kt  |  40 ++
 .../nullabilityWarnings/throw.fir.kt          |  26 ++
 .../uselessElvisInCall.fir.kt                 |  28 ++
 .../uselessElvisRightIsNull.fir.kt            |  39 ++
 .../platformTypes/nullableTypeArgument.fir.kt |   9 +
 .../tests/platformTypes/override.fir.kt       |  26 ++
 .../tests/platformTypes/rawOverrides.fir.kt   |  41 ++
 .../platformTypes/rawSamOverrides.fir.kt      |  41 ++
 .../platformTypes/rawTypes/arrays.fir.kt      |  44 +++
 .../platformTypes/rawTypes/errorType.fir.kt   |  12 +
 .../rawTypes/genericInnerClass.fir.kt         |  34 ++
 .../rawTypes/interClassesRecursion.fir.kt     |   4 +
 .../rawTypes/nonGenericRawMember.fir.kt       |  34 ++
 .../rawTypes/nonTrivialErasure.fir.kt         |  29 ++
 .../rawTypes/rawEnhancment.fir.kt             |  17 +
 .../rawTypes/rawSupertype.fir.kt              |  36 ++
 .../rawTypes/rawSupertypeOverride.fir.kt      |  41 ++
 .../rawTypes/rawTypeInUpperBound.fir.kt       |  38 ++
 .../rawTypes/rawWithInProjection.fir.kt       |  11 +
 .../rawTypes/recursiveBound.fir.kt            |  15 +
 .../platformTypes/rawTypes/samRaw.fir.kt      |  28 ++
 ...saveRawCapabilitiesAfterSubtitution.fir.kt |  20 +
 .../platformTypes/rawTypes/simple.fir.kt      |  39 ++
 .../rawTypes/starProjectionToRaw.fir.kt       |  25 ++
 .../rawTypes/typeEnhancement.fir.kt           |  27 ++
 .../tests/platformTypes/safeCall.fir.kt       |  15 +
 .../samAdapterInConstructor.fir.kt            |  14 +
 .../tests/platformTypes/samConstructor.fir.kt |  17 +
 .../supertypeArgumentsExplicit.fir.kt         |  13 +
 .../supertypeTypeArguments.fir.kt             |   3 +
 .../overriddenExtensions.fir.kt               |  63 +++
 .../saveAnnotationAfterSubstitution.fir.kt    |  43 ++
 ...ertypeDifferentParameterNullability.fir.kt |  33 ++
 ...supertypeDifferentReturnNullability.fir.kt |  35 ++
 .../tests/privateInFile/kt12429.fir.kt        |   4 +
 .../topLevelAnnotationCall.fir.kt             |  27 ++
 .../tests/privateInFile/visibility.fir.kt     |  54 +++
 ...roperDefaultInitializationInTailrec.fir.kt |  39 ++
 ...opertyMustHaveAccessorsOrBeAbstract.fir.kt |  25 ++
 .../blockBodyGetter.fir.kt                    |   3 +
 .../cantBeInferred.fir.kt                     |   7 +
 .../explicitGetterType.fir.kt                 |  18 +
 .../inferenceFromGetters/members.fir.kt       |  24 ++
 .../inferenceFromGetters/nullAsNothing.fir.kt |   9 +
 .../objectExpression.fir.kt                   |  36 ++
 .../inferenceFromGetters/overrides.fir.kt     |  41 ++
 .../primaryConstructorParameter.fir.kt        |  23 ++
 .../recursiveGetter.fir.kt                    |  20 +
 .../inferenceFromGetters/topLevel.fir.kt      |  21 +
 .../unsupportedInferenceFromGetters.fir.kt    |  71 ++++
 .../inferenceFromGetters/vars.fir.kt          |  21 +
 .../properties/lateinitOnTopLevel.fir.kt      |  14 +
 .../diagnostics/tests/publishedApi.fir.kt     |  71 ++++
 .../GenericClassVsPackage.fir.kt              |  76 ++++
 .../qualifiedExpression/JavaQualifier.fir.kt  |   9 +
 .../qualifiedExpression/PackageVsClass.fir.kt |  88 +++++
 .../PackageVsClass2.fir.kt                    |  33 ++
 .../PackageVsRootClass.fir.kt                 |  44 +++
 .../qualifiedExpression/TypeWithError.fir.kt  |  32 ++
 .../calleeExpressionAsCallExpression.fir.kt   |   2 +
 .../nullCalleeExpression.fir.kt               |   4 +
 .../visibleClassVsQualifiedClass.fir.kt       |  58 +++
 .../tests/reassignment/afterfor.fir.kt        |  10 +
 .../tests/reassignment/dowhile.fir.kt         |  10 +
 .../tests/reassignment/else.fir.kt            |  11 +
 .../tests/reassignment/foronly.fir.kt         |   9 +
 .../diagnostics/tests/reassignment/if.fir.kt  |  10 +
 .../tests/reassignment/ifelse.fir.kt          |  13 +
 .../tests/reassignment/noifelse.fir.kt        |   6 +
 .../tests/reassignment/when.fir.kt            |  10 +
 .../tests/reassignment/whiletrue.fir.kt       |  11 +
 .../tests/recovery/absentLeftHandSide.fir.kt  |  16 +
 .../tests/recovery/emptyTypeArgs.fir.kt       |   3 +
 .../tests/recovery/namelessInJava.fir.kt      |  18 +
 .../tests/recovery/namelessMembers.fir.kt     |  17 +
 .../namelessToplevelDeclarations.fir.kt       |  26 ++
 .../ClassRedeclarationInDifferentFiles.fir.kt |  11 +
 .../ConflictingExtensionProperties.fir.kt     |   4 +
 ...plicateParameterNamesInFunctionType.fir.kt |   7 +
 .../tests/redeclarations/EnumName.fir.kt      |   3 +
 .../FunVsCtorInDifferentFiles.fir.kt          |  10 +
 .../MultiFilePackageRedeclaration.fir.kt      |   7 +
 ...eclarationForClassesInDefaultObject.fir.kt |  12 +
 ...rEnumEntriesAndDefaultObjectMembers.fir.kt |  11 +
 .../PropertyAndFunInClass.fir.kt              |   9 +
 .../PropertyAndInnerClass.fir.kt              |  13 +
 .../RedeclarationInDefaultObject.fir.kt       |   6 +
 .../RedeclarationInMultiFile.fir.kt           |   9 +
 .../RedeclarationMainInFile.fir.kt            |   4 +
 .../RedeclarationMainInMultiFile.fir.kt       |   5 +
 .../RedeclarationParameterlessMain.fir.kt     |   5 +
 ...declarationParameterlessMainInvalid.fir.kt |   7 +
 ...declarationParameterlessMain_before.fir.kt |   7 +
 ...RedeclarationSuspendMainInMultiFile.fir.kt |   5 +
 ...rationSuspendMainInMultiFile_before.fir.kt |   7 +
 .../redeclarations/Redeclarations.fir.kt      |  15 +
 .../RedeclarationsInObjects.fir.kt            |   9 +
 .../RedeclaredTypeParameters.fir.kt           |   6 +
 .../RedeclaringPrivateToFile.fir.kt           |  49 +++
 .../SingletonAndFunctionSameName.fir.kt       |  21 +
 .../TopLevelPropertyVsClassifier.fir.kt       |  13 +
 .../redeclarations/TypeAliasCtorVsFun.fir.kt  |  14 +
 .../redeclarations/TypeAliasVsClass.fir.kt    |  18 +
 .../redeclarations/TypeAliasVsProperty.fir.kt |  16 +
 .../interfaceTypeParameters.fir.kt            |   6 +
 .../tests/redeclarations/kt2418.fir.kt        |  27 ++
 .../tests/redeclarations/kt2438.fir.kt        |  22 ++
 .../tests/redeclarations/kt470.fir.kt         |  37 ++
 ...nFunShadowedByInnerClassConstructor.fir.kt |  31 ++
 .../extensionFunShadowedByMemberFun.fir.kt    |  32 ++
 ...nShadowedByMemberPropertyWithInvoke.fir.kt |  18 +
 ...onFunShadowedBySynthesizedMemberFun.fir.kt |   5 +
 .../extensionFunVsMemberExtensionFun.fir.kt   |   5 +
 .../extensionOnErrorType.fir.kt               |   7 +
 .../extensionOnNullableReceiver.fir.kt        |   7 +
 ...ionPropertyShadowedByMemberProperty.fir.kt |  22 ++
 .../extensionShadowedByDelegatedMember.fir.kt |  16 +
 .../extensionVsNonPublicMember.fir.kt         |  47 +++
 .../infixExtensionVsNonInfixMember.fir.kt     |   7 +
 .../localExtensionShadowedByMember.fir.kt     |   7 +
 .../memberExtensionShadowedByMember.fir.kt    |   9 +
 ...peratorExtensionVsNonOperatorMember.fir.kt |   7 +
 .../typeParameterWithTwoBounds.fir.kt         |   8 +
 .../reflection/noReflectionInClassPath.fir.kt |  62 +++
 .../AmbiguityOnLazyTypeComputation.fir.kt     |  12 +
 .../AssignmentsUnderOperators.fir.kt          |   6 +
 .../tests/regressions/CoercionToUnit.fir.kt   |   9 +
 .../tests/regressions/DoubleDefine.fir.kt     |  65 +++
 ...rorsOnIbjectExpressionsAsParameters.fir.kt |   5 +
 .../tests/regressions/Jet11.fir.kt            |   4 +
 .../tests/regressions/Jet121.fir.kt           |  14 +
 .../tests/regressions/Jet124.fir.kt           |   8 +
 .../tests/regressions/Jet169.fir.kt           |   8 +
 .../tests/regressions/Jet17.fir.kt            |   6 +
 .../tests/regressions/Jet183-1.fir.kt         |  21 +
 .../tests/regressions/Jet183.fir.kt           |  15 +
 .../tests/regressions/Jet53.fir.kt            |   5 +
 .../tests/regressions/Jet67.fir.kt            |   4 +
 .../tests/regressions/Jet68.fir.kt            |  11 +
 .../tests/regressions/Jet69.fir.kt            |  10 +
 .../tests/regressions/Jet72.fir.kt            |  18 +
 .../tests/regressions/Jet81.fir.kt            |  29 ++
 .../regressions/OrphanStarProjection.fir.kt   |   3 +
 .../tests/regressions/OutProjections.fir.kt   |  22 ++
 .../regressions/OverrideResolution.fir.kt     |  16 +
 .../regressions/SpecififcityByReceiver.fir.kt |   9 +
 .../TypeMismatchOnUnaryOperations.fir.kt      |  16 +
 .../TypeParameterAsASupertype.fir.kt          |   1 +
 .../UnavaliableQualifiedThis.fir.kt           |  13 +
 .../WrongTraceInCallResolver.fir.kt           |   9 +
 ...tResultSubstitutorForErrorCandidate.fir.kt |  10 +
 .../regressions/delegationWithReceiver.fir.kt |  10 +
 .../tests/regressions/ea40964.fir.kt          |   8 +
 .../tests/regressions/ea43298.fir.kt          |   3 +
 .../tests/regressions/ea53340.fir.kt          |   7 +
 .../tests/regressions/ea65509.fir.kt          |   5 +
 .../tests/regressions/ea66984.fir.kt          |   2 +
 .../tests/regressions/ea69735.fir.kt          |   5 +
 .../tests/regressions/ea72837.fir.kt          |  10 +
 .../tests/regressions/ea76264.fir.kt          |   4 +
 .../tests/regressions/intchar.fir.kt          |   1 +
 .../regressions/itselfAsUpperBound.fir.kt     |   3 +
 .../itselfAsUpperBoundInClass.fir.kt          |   1 +
 .../itselfAsUpperBoundInClassNotNull.fir.kt   |   1 +
 .../itselfAsUpperBoundLocal.fir.kt            |   5 +
 .../itselfAsUpperBoundMember.fir.kt           |   5 +
 .../itselfAsUpperBoundNotNull.fir.kt          |   3 +
 .../tests/regressions/kt10243.fir.kt          |  17 +
 .../tests/regressions/kt10243a.fir.kt         |  11 +
 .../tests/regressions/kt10633.fir.kt          |  19 +
 .../tests/regressions/kt10824.fir.kt          |  52 +++
 .../tests/regressions/kt10843.fir.kt          |   8 +
 .../tests/regressions/kt127.fir.kt            |  18 +
 .../tests/regressions/kt128.fir.kt            |  12 +
 .../tests/regressions/kt13685.fir.kt          |   7 +
 .../tests/regressions/kt13954.fir.kt          |  26 ++
 .../tests/regressions/kt14740.fir.kt          |  20 +
 .../tests/regressions/kt1489_1728.fir.kt      |  31 ++
 .../tests/regressions/kt1550.fir.kt           |  12 +
 .../tests/regressions/kt16086.fir.kt          |  21 +
 .../tests/regressions/kt16086_2.fir.kt        |  13 +
 .../tests/regressions/kt1639-JFrame.fir.kt    |  12 +
 .../tests/regressions/kt1647.fir.kt           |  11 +
 .../tests/regressions/kt1736.fir.kt           |  10 +
 .../tests/regressions/kt174.fir.kt            |   7 +
 .../tests/regressions/kt201.fir.kt            |   8 +
 .../tests/regressions/kt235.fir.kt            |  49 +++
 .../tests/regressions/kt2376.fir.kt           |  10 +
 .../tests/regressions/kt24488.fir.kt          |  15 +
 .../tests/regressions/kt251.fir.kt            |  34 ++
 .../tests/regressions/kt258.fir.kt            |  10 +
 .../tests/regressions/kt26-1.fir.kt           |   9 +
 .../diagnostics/tests/regressions/kt26.fir.kt |  12 +
 .../tests/regressions/kt26303.fir.kt          |  17 +
 .../tests/regressions/kt2768.fir.kt           |  20 +
 .../tests/regressions/kt28001.fir.kt          |  32 ++
 .../tests/regressions/kt282.fir.kt            |  19 +
 .../tests/regressions/kt287.fir.kt            |  12 +
 .../tests/regressions/kt2956.fir.kt           |   1 +
 .../tests/regressions/kt302.fir.kt            |  13 +
 .../tests/regressions/kt306.fir.kt            |  23 ++
 .../tests/regressions/kt307.fir.kt            |  11 +
 .../tests/regressions/kt312.fir.kt            |  10 +
 .../tests/regressions/kt313.fir.kt            |  11 +
 .../tests/regressions/kt316.fir.kt            |  10 +
 .../tests/regressions/kt31975.fir.kt          |  18 +
 .../tests/regressions/kt32205.fir.kt          |  12 +
 .../tests/regressions/kt328.fir.kt            |  29 ++
 .../tests/regressions/kt32836.fir.kt          |  17 +
 .../tests/regressions/kt334.fir.kt            |   8 +
 .../tests/regressions/kt335.336.fir.kt        |  13 +
 .../tests/regressions/kt337.fir.kt            |  14 +
 .../tests/regressions/kt352.fir.kt            |  29 ++
 .../tests/regressions/kt353.fir.kt            |  33 ++
 .../tests/regressions/kt3535.fir.kt           |   9 +
 .../tests/regressions/kt3647.fir.kt           |   9 +
 .../tests/regressions/kt3731.fir.kt           |  17 +
 .../tests/regressions/kt3810.fir.kt           |   5 +
 .../tests/regressions/kt385.109.441.fir.kt    |  33 ++
 .../tests/regressions/kt394.fir.kt            |  11 +
 .../tests/regressions/kt398.fir.kt            |  11 +
 .../tests/regressions/kt399.fir.kt            |  11 +
 .../tests/regressions/kt402.fir.kt            |   8 +
 .../diagnostics/tests/regressions/kt41.fir.kt |  11 +
 .../tests/regressions/kt411.fir.kt            |  69 ++++
 .../tests/regressions/kt439.fir.kt            |   5 +
 .../tests/regressions/kt442.fir.kt            |  31 ++
 .../tests/regressions/kt443.fir.kt            |  14 +
 .../tests/regressions/kt455.fir.kt            |  10 +
 .../tests/regressions/kt456.fir.kt            |  30 ++
 .../tests/regressions/kt459.fir.kt            |   8 +
 .../tests/regressions/kt469.fir.kt            |  28 ++
 .../tests/regressions/kt4693.fir.kt           |   8 +
 .../tests/regressions/kt4827.fir.kt           |  16 +
 .../tests/regressions/kt498.fir.kt            |   8 +
 .../tests/regressions/kt524.fir.kt            |  14 +
 ...kt526UnresolvedReferenceInnerStatic.fir.kt |  15 +
 .../tests/regressions/kt5326.fir.kt           |  11 +
 .../tests/regressions/kt5362.fir.kt           |  31 ++
 .../tests/regressions/kt549.fir.kt            |  17 +
 .../tests/regressions/kt557.fir.kt            |  12 +
 .../tests/regressions/kt571.fir.kt            |   3 +
 .../tests/regressions/kt575.fir.kt            |  32 ++
 .../diagnostics/tests/regressions/kt58.fir.kt |  91 +++++
 .../tests/regressions/kt580.fir.kt            |  22 ++
 .../tests/regressions/kt588.fir.kt            |  14 +
 .../tests/regressions/kt597.fir.kt            |  19 +
 .../tests/regressions/kt600.fir.kt            |   8 +
 .../tests/regressions/kt604.fir.kt            |  20 +
 .../tests/regressions/kt618.fir.kt            |  28 ++
 .../tests/regressions/kt629.fir.kt            |  23 ++
 .../tests/regressions/kt630.fir.kt            |   6 +
 .../tests/regressions/kt6508.fir.kt           |  24 ++
 .../tests/regressions/kt688.fir.kt            |  14 +
 .../tests/regressions/kt691.fir.kt            |   2 +
 .../tests/regressions/kt701.fir.kt            |  17 +
 .../tests/regressions/kt716.fir.kt            |  16 +
 .../tests/regressions/kt743.fir.kt            |   7 +
 .../tests/regressions/kt750.fir.kt            |  10 +
 .../tests/regressions/kt7585/base.fir.kt      |  20 +
 .../tests/regressions/kt7585/java.fir.kt      |  30 ++
 .../regressions/kt7585/twoparents.fir.kt      |  16 +
 .../tests/regressions/kt762.fir.kt            |   4 +
 .../tests/regressions/kt7804.fir.kt           |  65 +++
 .../tests/regressions/kt847.fir.kt            |   4 +
 .../tests/regressions/kt860.fir.kt            |  14 +
 .../tests/regressions/kt9384.fir.kt           |  11 +
 .../tests/regressions/kt9620.fir.kt           |  14 +
 .../tests/regressions/kt9633.fir.kt           |   2 +
 .../tests/regressions/kt9682.fir.kt           |  28 ++
 .../tests/regressions/kt9808.fir.kt           |   8 +
 .../tests/regressions/noThis.fir.kt           |  10 +
 .../propertyWithExtensionTypeInvoke.fir.kt    |   7 +
 .../regressions/resolveSubclassOfList.fir.kt  |   7 +
 .../tests/resolve/CycleInTypeArgs.fir.kt      |   3 +
 .../tests/resolve/HiddenDeclarations.fir.kt   |  74 ++++
 ...yOnPropertiesWithTheSamePackageName.fir.kt |  30 ++
 ...tyWithTwoCorrespondingFunctionTypes.fir.kt |  11 +
 .../anonymousObjectFromTopLevelMember.fir.kt  |  24 ++
 .../resolve/callableReferenceInCST.fir.kt     |  36 ++
 .../capturedTypesInLambdaParameter.fir.kt     |  42 ++
 .../resolve/constructorVsCompanion.fir.kt     |  23 ++
 .../dslMarker/annotatedFunctionType.fir.kt    |  57 +++
 .../annotatedFunctionType_1_4.fir.kt          |  58 +++
 .../dslMarker/annotatedTypeArgument.fir.kt    |  26 ++
 .../dslMarker/dslMarkerOnTypealias.fir.kt     |  28 ++
 .../dslMarkerWithTypealiasRecursion.fir.kt    |  24 ++
 .../resolve/dslMarker/inheritedMarker.fir.kt  |  30 ++
 .../dslMarker/insideTopLevelExtension.fir.kt  |  23 ++
 ...nsideTopLevelExtensionAnnotatedType.fir.kt |  22 ++
 .../tests/resolve/dslMarker/kt29948.fir.kt    |  19 +
 .../tests/resolve/dslMarker/kt31360.fir.kt    |  25 ++
 ...kedReceiverWithCapturedTypeArgument.fir.kt |  11 +
 .../dslMarker/markersIntersection.fir.kt      |  93 +++++
 .../dslMarker/nestedWithSameReceiver.fir.kt   |  40 ++
 .../tests/resolve/dslMarker/properties.fir.kt |  62 +++
 .../dslMarker/simpleAnnotatedClasses.fir.kt   |  27 ++
 .../dslMarker/simpleAnnotatedTypes.fir.kt     |  26 ++
 ...substitutedReceiverAnnotatedClasses.fir.kt |  27 ++
 .../substitutedReceiverAnnotatedType.fir.kt   |  27 ++
 .../dslMarker/threeImplicitReceivers.fir.kt   | 111 ++++++
 .../dslMarker/threeImplicitReceivers2.fir.kt  | 106 +++++
 .../dslMarker/twoImplicitReceivers.fir.kt     | 102 +++++
 .../resolve/dslMarker/twoLanguages.fir.kt     | 104 +++++
 .../dslMarker/unsupportedFeature.fir.kt       |  28 ++
 .../resolve/dslMarker/useOfExtensions.fir.kt  |  27 ++
 .../tests/resolve/dslMarker/usingWith.fir.kt  |  24 ++
 .../resolve/dslMarker/usingWithThis.fir.kt    |  30 ++
 .../resolve/implicitReceiverProperty.fir.kt   |  33 ++
 .../incompleteConstructorInvocation.fir.kt    |  10 +
 .../resolve/inferenceInLinkedLambdas.fir.kt   |   8 +
 ...inkedLambdasDependentOnExpectedType.fir.kt |   7 +
 .../tests/resolve/invoke/KT-4372.fir.kt       |  22 ++
 .../invoke/errors/ambiguityForInvoke.fir.kt   |  11 +
 .../invoke/errors/invisibleInvoke.fir.kt      |  10 +
 .../receiverPresenceErrorForInvoke.fir.kt     |  11 +
 .../errors/typeInferenceErrorForInvoke.fir.kt |  14 +
 .../invoke/errors/unresolvedInvoke.fir.kt     |   5 +
 .../invoke/errors/unsafeCallWithInvoke.fir.kt |  10 +
 .../wrongReceiverForInvokeOnExpression.fir.kt |  17 +
 .../errors/wrongReceiverTypeForInvoke.fir.kt  |  10 +
 .../extensionValueAsNonExtension.fir.kt       |  23 ++
 ...tionExpectedWhenSeveralInvokesExist.fir.kt |  14 +
 .../resolve/invoke/implicitInvoke.fir.kt      |  33 ++
 .../resolve/invoke/invokeAndSmartCast.fir.kt  |  22 ++
 .../resolve/invoke/invokeAsExtension.fir.kt   |  61 +++
 .../resolve/invoke/invokeAsMember.fir.kt      |  60 +++
 .../invoke/invokeAsMemberExtension.fir.kt     | 123 ++++++
 ...AsMemberExtensionToExplicitReceiver.fir.kt |  12 +
 .../invokeNonExtensionLambdaInContext.fir.kt  |   7 +
 ...OnVariableWithExtensionFunctionType.fir.kt |  84 ++++
 .../tests/resolve/invoke/kt3772.fir.kt        |  27 ++
 .../kt3833-invokeInsideNestedClass.fir.kt     |  35 ++
 ...kt4204-completeNestedCallsForInvoke.fir.kt |  24 ++
 .../resolve/invoke/kt4321InvokeOnEnum.fir.kt  |  35 ++
 .../tests/resolve/invoke/kt9517.fir.kt        |  16 +
 .../tests/resolve/invoke/kt9805.fir.kt        |  17 +
 ...tFunctionExpectedWhenOneInvokeExist.fir.kt |  13 +
 .../resolve/invoke/valNamedInvoke.fir.kt      |   9 +
 .../invoke/wrongInvokeExtension.fir.kt        |  18 +
 .../tests/resolve/localObject.fir.kt          |   4 +
 ...analyzeArgsInFreeExpressionPosition.fir.kt |  12 +
 .../analyzeUnmappedArguments.fir.kt           |   9 +
 .../nestedCalls/argumentsInParentheses.fir.kt |  20 +
 ...eInferenceForNestedInNoneApplicable.fir.kt |  11 +
 .../completeUnmappedArguments.fir.kt          |  14 +
 .../nestedCalls/kt5971NestedSafeCall.fir.kt   |   9 +
 .../tests/resolve/nestedCalls/kt7597.fir.kt   |   8 +
 ...nyInapplicableCandidatesWithLambdas.fir.kt |  53 +++
 .../nestedCalls/twoTypeParameters.fir.kt      |  17 +
 .../tests/resolve/newLineLambda.fir.kt        | 118 ++++++
 .../tests/resolve/noCandidates/kt2787.fir.kt  |   6 +
 .../noCandidates/resolvedToClassifier.fir.kt  |  19 +
 .../resolvedToClassifierWithReceiver.fir.kt   |  39 ++
 .../resolve/objectLiteralAsArgument.fir.kt    |  36 ++
 .../overloadConflicts/allLambdas.fir.kt       |  10 +
 .../extensionReceiverAndVarargs.fir.kt        |  12 +
 .../overloadConflicts/genericClash.fir.kt     |  20 +
 .../genericWithProjection.fir.kt              |  11 +
 .../resolve/overloadConflicts/kt10472.fir.kt  |  13 +
 .../resolve/overloadConflicts/kt10640.fir.kt  |  10 +
 .../resolve/overloadConflicts/kt31670.fir.kt  |  16 +
 .../overloadConflicts/kt31670_compat.fir.kt   |  16 +
 .../resolve/overloadConflicts/kt31758.fir.kt  |  26 ++
 .../overloadConflicts/kt31758_compat.fir.kt   |  26 ++
 .../overloadConflicts/numberOfDefaults.fir.kt |  10 +
 .../overloadConflicts/originalExamples.fir.kt |  21 +
 ...ionOnNullableContravariantParameter.fir.kt |  24 ++
 ...llableContravariantParameter_compat.fir.kt |  24 ++
 .../varargWithMoreSpecificSignature.fir.kt    |   9 +
 .../resolve/overloadConflicts/varargs.fir.kt  |  11 +
 .../varargsInDifferentPositions.fir.kt        |  13 +
 .../overloadConflicts/varargsMixed.fir.kt     |  13 +
 .../varargsWithRecursiveGenerics.fir.kt       |  21 +
 .../overloadConflicts/withVariance.fir.kt     |  10 +
 ...ameterAsDefaultValueInLocalFunction.fir.kt |   6 +
 .../priority/invokeExtensionVsOther.fir.kt    |  18 +
 .../priority/invokeExtensionVsOther2.fir.kt   |  13 +
 .../tests/resolve/priority/kt10219.fir.kt     |  22 ++
 .../tests/resolve/priority/kt10510.fir.kt     |  13 +
 .../tests/resolve/priority/kt9810.fir.kt      |  12 +
 .../tests/resolve/priority/kt9965.fir.kt      |  20 +
 .../priority/localExtVsNonLocalExt.fir.kt     |  16 +
 .../resolve/priority/memberVsLocalExt.fir.kt  |  18 +
 .../staticVsImplicitReceiverMember.fir.kt     |  19 +
 .../synthesizedMembersVsExtension.fir.kt      |  10 +
 .../syntheticPropertiesVsExtensions.fir.kt    |  29 ++
 .../syntheticPropertiesVsMembers.fir.kt       |  36 ++
 .../resolveAnnotatedLambdaArgument.fir.kt     |  12 +
 .../resolveTypeArgsForUnresolvedCall.fir.kt   |   4 +
 .../resolveWithFunctionLiteralWithId.fir.kt   |  32 ++
 .../resolveWithFunctionLiterals.fir.kt        |  30 ++
 ...resolveWithFunctionLiteralsOverload.fir.kt |  31 ++
 .../tests/resolve/resolveWithGenerics.fir.kt  |  21 +
 .../resolveWithRedeclarationError.fir.kt      |  34 ++
 ...eWithSpecifiedFunctionLiteralWithId.fir.kt |  36 ++
 .../resolve/resolveWithoutGenerics.fir.kt     |  20 +
 .../specialConstructions/constantsInIf.fir.kt |  14 +
 .../specialConstructions/elvisAsCall.fir.kt   |  37 ++
 .../exclExclAsCall.fir.kt                     |  29 ++
 .../inferenceForElvis.fir.kt                  |   8 +
 .../multipleSuperClasses.fir.kt               |  29 ++
 .../reportTypeMismatchDeeplyOnBranches.fir.kt |  28 ++
 ...ameterInDefaultValueInLocalFunction.fir.kt |   7 +
 .../resolve/wrongNumberOfTypeArguments.fir.kt |  15 +
 .../tests/resolve/wrongReceiver.fir.kt        |  21 +
 .../diagnostics/tests/safeCall.fir.kt         |  15 +
 .../samConversions/DisabledForKTSimple.fir.kt |  20 +
 .../samConversions/GenericSubstitution.fir.kt |  29 ++
 .../GenericSubstitutionKT.fir.kt              |  27 ++
 .../samConversions/OverloadPriority.fir.kt    |  31 ++
 .../samConversions/OverloadPriorityKT.fir.kt  |  30 ++
 .../SAMAfterSubstitution.fir.kt               |  18 +
 .../SAMAfterSubstitutionKT.fir.kt             |  17 +
 .../tests/samConversions/SimpleCorrect.fir.kt |  34 ++
 .../samConversions/SimpleCorrectKT.fir.kt     |  31 ++
 ...kSamConversionsAreDisabledByDefault.fir.kt |  31 ++
 .../AmbiguityBetweenRootAndPackage.fir.kt     |  12 +
 .../scopes/AmbiguousNonExtensions.fir.kt      |  18 +
 .../NoAmbiguityBetweenRootAndPackage.fir.kt   |  12 +
 .../scopes/VisibilityInClassObject.fir.kt     |  33 ++
 .../scopes/VisibilityInheritModifier.fir.kt   |  85 ++++
 .../classHeader/annotationOnClass.fir.kt      |  51 +++
 .../annotationOnConstructors.fir.kt           |  65 +++
 .../classHeader/classGenericParameters.fir.kt |  20 +
 .../scopes/classHeader/classParents.fir.kt    |  12 +
 .../classHeader/companionObjectParents.fir.kt |  25 ++
 ...nionObjectSuperConstructorArguments.fir.kt |  19 +
 .../scopes/classHeader/constructors.fir.kt    |  65 +++
 .../scopes/classHeader/delegation.fir.kt      |  50 +++
 .../scopes/classHeader/objectParents.fir.kt   |  11 +
 .../objectSuperConstructorArguments.fir.kt    |   8 +
 .../classHeader/simpleDelegation.fir.kt       |  10 +
 .../superConstructorArguments.fir.kt          |  48 +++
 ...ctorArgumentsInSecondaryConstructor.fir.kt |  50 +++
 .../tests/scopes/genericVsNested.fir.kt       |  57 +++
 .../implicitReceiverMemberVsParameter.fir.kt  |   5 +
 .../scopes/inheritance/companionObject.fir.kt |  41 ++
 .../companionObjectAfterJava.fir.kt           |  52 +++
 .../inheritance/companionObjectsOrder.fir.kt  |  37 ++
 .../scopes/inheritance/innerClasses.fir.kt    |  66 ++++
 .../tests/scopes/inheritance/kt3856.fir.kt    |  33 ++
 .../scopes/inheritance/methodsPriority.fir.kt |  34 ++
 .../nestedClassesFromInterface.fir.kt         |  27 ++
 .../inheritance/nestedCompanionClass.fir.kt   |  39 ++
 .../nestedCompanionClassVsNested.fir.kt       |  95 +++++
 .../nestedCompanionClassVsNestedJava.fir.kt   |  47 +++
 .../scopes/inheritance/nestedFromJava.fir.kt  |  90 +++++
 .../nestedFromJavaAfterKotlin.fir.kt          |  82 ++++
 .../inheritance/nestedVsToplevelClass.fir.kt  |  38 ++
 .../inheritance/severalCompanions.fir.kt      |  22 ++
 ...StaticMembersOfParentClassJKJ_after.fir.kt |  55 +++
 ...taticMembersOfParentClassJKJ_before.fir.kt |  55 +++
 ...sToStaticMembersOfParentClass_after.fir.kt |  46 +++
 ...ToStaticMembersOfParentClass_before.fir.kt |  46 +++
 .../inheritFromContainingClass_after.fir.kt   |  54 +++
 .../inheritFromContainingClass_before.fir.kt  |  54 +++
 .../inheritFromJavaAfterKotlin_after.fir.kt   |  50 +++
 .../inheritFromJavaAfterKotlin_before.fir.kt  |  50 +++
 .../inheritFromJava_after.fir.kt              |  39 ++
 .../inheritFromJava_before.fir.kt             |  39 ++
 .../statics/hidePrivateByPublic.fir.kt        |  36 ++
 .../scopes/inheritance/statics/jjkj.fir.kt    |  43 ++
 .../scopes/inheritance/statics/kjk.fir.kt     |  37 ++
 .../inheritance/statics/localVsStatic.fir.kt  |  27 ++
 .../inheritance/statics/nameClash0.fir.kt     |  32 ++
 .../inheritance/statics/nameClash1.fir.kt     |  32 ++
 .../inheritance/statics/nameClash2.fir.kt     |  66 ++++
 .../statics/oneInterfaceManyTimes.fir.kt      |  55 +++
 .../inheritance/statics/overloadStatic.fir.kt |  20 +
 .../statics/staticFunVsImport.fir.kt          |  50 +++
 .../statics/staticPropertyVsImport.fir.kt     |  59 +++
 .../statics/staticVsCompanion.fir.kt          |  36 ++
 .../inheritance/statics/staticVsMember.fir.kt |  69 ++++
 .../inheritance/statics/staticVsOuter.fir.kt  |  19 +
 .../statics/staticsFromjava.fir.kt            |  51 +++
 .../statics/staticsFromjavaAfterKotlin.fir.kt |  27 ++
 ...initializerScopeOfExtensionProperty.fir.kt |  31 ++
 .../tests/scopes/invisibleSetter.fir.kt       |   9 +
 .../diagnostics/tests/scopes/kt1078.fir.kt    |  16 +
 .../diagnostics/tests/scopes/kt1080.fir.kt    |  19 +
 .../diagnostics/tests/scopes/kt1244.fir.kt    |  13 +
 .../diagnostics/tests/scopes/kt1248.fir.kt    |  12 +
 .../diagnostics/tests/scopes/kt151.fir.kt     |  40 ++
 .../diagnostics/tests/scopes/kt1579.fir.kt    |  10 +
 .../tests/scopes/kt1579_map_entry.fir.kt      |  19 +
 .../diagnostics/tests/scopes/kt1580.fir.kt    |  15 +
 .../diagnostics/tests/scopes/kt1642.fir.kt    |   9 +
 .../diagnostics/tests/scopes/kt1738.fir.kt    |  11 +
 .../diagnostics/tests/scopes/kt1805.fir.kt    |  20 +
 .../diagnostics/tests/scopes/kt1806.fir.kt    |  24 ++
 .../diagnostics/tests/scopes/kt1822.fir.kt    |  30 ++
 .../diagnostics/tests/scopes/kt1942.fir.kt    |  19 +
 .../diagnostics/tests/scopes/kt2262.fir.kt    |  16 +
 .../tests/scopes/kt250.617.10.fir.kt          |  49 +++
 .../diagnostics/tests/scopes/kt323.fir.kt     |  18 +
 .../diagnostics/tests/scopes/kt37.fir.kt      |  16 +
 .../diagnostics/tests/scopes/kt587.fir.kt     |  11 +
 .../diagnostics/tests/scopes/kt900-1.fir.kt   |  24 ++
 .../diagnostics/tests/scopes/kt900-2.fir.kt   |  33 ++
 .../diagnostics/tests/scopes/kt900.fir.kt     |  69 ++++
 .../diagnostics/tests/scopes/kt939.fir.kt     |  18 +
 .../diagnostics/tests/scopes/kt9430.fir.kt    |  16 +
 .../complexCompanion.fir.kt                   |  18 +
 .../protectedVisibility/constructors.fir.kt   |  22 ++
 .../constructorsInner.fir.kt                  |  19 +
 .../innerClassInJava.fir.kt                   |  24 ++
 .../innerProtectedClass.fir.kt                |  13 +
 .../javaInheritedInKotlin.fir.kt              |  58 +++
 .../scopes/protectedVisibility/kt7971.fir.kt  |  22 ++
 .../nonSuperCallConstructor.fir.kt            |  27 ++
 ...CallConstructorJavaDifferentPackage.fir.kt |  32 ++
 ...SuperCallConstructorJavaSamePackage.fir.kt |  30 ++
 .../protectedCallOnSubClass.fir.kt            |  15 +
 .../smartcastOnExtensionReceiver.fir.kt       |   9 +
 .../syntheticPropertyExtensions.fir.kt        |  45 +++
 .../syntheticSAMExtensions.fir.kt             |  31 ++
 .../unstableSmartCast.fir.kt                  |  19 +
 .../protectedVisibility/withSmartcast.fir.kt  |  30 ++
 .../tests/scopes/sameClassNameResolve.fir.kt  |  10 +
 .../scopes/stopResolutionOnAmbiguity.fir.kt   |  20 +
 .../tests/scopes/visibility.fir.kt            |  95 +++++
 .../tests/scopes/visibility2.fir.kt           |  49 +++
 .../tests/scopes/visibility3.fir.kt           |  47 +++
 .../tests/sealed/DerivedTopLevel.fir.kt       |  10 +
 .../tests/sealed/DoubleInner.fir.kt           |   9 +
 .../tests/sealed/ExhaustiveOnRoot.fir.kt      |  23 ++
 .../tests/sealed/ExhaustiveOnTree.fir.kt      |  34 ++
 .../sealed/ExhaustiveOnTriangleStar.fir.kt    |  24 ++
 .../tests/sealed/ExhaustiveWhen.fir.kt        |  16 +
 .../sealed/ExhaustiveWhenDoubleInner.fir.kt   |  16 +
 .../sealed/ExhaustiveWhenMultipleInner.fir.kt |  47 +++
 .../tests/sealed/ExhaustiveWhenNegated.fir.kt |  16 +
 .../sealed/ExhaustiveWhenNegatedTwice.fir.kt  |  17 +
 .../ExhaustiveWhenOnNestedSealed.fir.kt       |  20 +
 .../sealed/ExhaustiveWhenOnNullable.fir.kt    |  17 +
 .../ExhaustiveWhenWithAdditionalMember.fir.kt |  18 +
 .../sealed/ExhaustiveWhenWithElse.fir.kt      |  15 +
 .../diagnostics/tests/sealed/Local.fir.kt     |  13 +
 .../tests/sealed/LocalSealed.fir.kt           |   3 +
 .../tests/sealed/NestedSealed.fir.kt          |  45 +++
 .../tests/sealed/NeverConstructed.fir.kt      |   3 +
 .../sealed/NeverDerivedFromNested.fir.kt      |   9 +
 .../diagnostics/tests/sealed/NeverEnum.fir.kt |   6 +
 .../tests/sealed/NeverFinal.fir.kt            |   3 +
 .../tests/sealed/NeverInterface.fir.kt        |   3 +
 .../tests/sealed/NeverObject.fir.kt           |   3 +
 .../diagnostics/tests/sealed/NeverOpen.fir.kt |   3 +
 .../tests/sealed/NonExhaustiveWhen.fir.kt     |  14 +
 .../sealed/NonExhaustiveWhenNegated.fir.kt    |  14 +
 ...NonExhaustiveWhenWithAdditionalCase.fir.kt |  22 ++
 .../NonExhaustiveWhenWithAnyCase.fir.kt       |  15 +
 .../tests/sealed/NonPrivateConstructor.fir.kt |   7 +
 .../diagnostics/tests/sealed/NotFinal.fir.kt  |  10 +
 .../tests/sealed/OperationWhen.fir.kt         |  20 +
 .../tests/sealed/RedundantAbstract.fir.kt     |   3 +
 .../diagnostics/tests/sealed/TreeWhen.fir.kt  |  13 +
 .../tests/sealed/TreeWhenFunctional.fir.kt    |  11 +
 .../sealed/TreeWhenFunctionalNoIs.fir.kt      |  23 ++
 .../tests/sealed/WhenOnEmptySealed.fir.kt     |  11 +
 .../tests/sealed/WithInterface.fir.kt         |  10 +
 ...mentsResolveInBodyAndDelegationCall.fir.kt |  25 ++
 .../classInitializersWithoutPrimary.fir.kt    |   4 +
 .../companionObjectScope.fir.kt               |  17 +
 .../constructorCallType.fir.kt                |  28 ++
 .../constructorInObject.fir.kt                |  20 +
 .../constructorInTrait.fir.kt                 |   3 +
 .../ctrsAnnotationResolve.fir.kt              |  12 +
 .../cyclicDelegationCalls.fir.kt              |  39 ++
 .../secondaryConstructors/dataClasses.fir.kt  |  14 +
 .../dataFlowInDelegationCall.fir.kt           |   7 +
 .../delegationByWithoutPrimary.fir.kt         |   6 +
 .../tests/secondaryConstructors/enums.fir.kt  |  40 ++
 .../errorsOnEmptyDelegationCall.fir.kt        |  42 ++
 .../expectedPrimaryConstructorCall.fir.kt     |   8 +
 .../secondaryConstructors/generics.fir.kt     |  21 +
 .../secondaryConstructors/generics2.fir.kt    |  27 ++
 .../secondaryConstructors/generics3.fir.kt    |  16 +
 ...seGenericFromInnerExtendingSameBase.fir.kt |  12 +
 ...eGenericFromInnerExtendingSameBase2.fir.kt |  13 +
 .../accessBaseWithSameExtension.fir.kt        |  12 +
 .../accessGenericBaseWithSameExtension.fir.kt |  13 +
 .../innerInstanceCreation.fir.kt              |  11 +
 .../headerCallChecker/lambdaAsArgument.fir.kt |  15 +
 .../headerCallChecker/memberFunAccess.fir.kt  |   7 +
 .../objectLiteralAsArgument.fir.kt            |  12 +
 ...bjectLiteralAsDefaultValueParameter.fir.kt |  11 +
 .../headerCallChecker/operatorCall.fir.kt     |  13 +
 .../headerCallChecker/passingInstance.fir.kt  |   8 +
 .../headerCallChecker/propertyAccess.fir.kt   |   7 +
 .../propertyAccessUnitialized.fir.kt          |   7 +
 .../headerCallChecker/superFunAccess.fir.kt   |   8 +
 .../superFunAccessOverriden.fir.kt            |   9 +
 .../superPropertyAccess.fir.kt                |   6 +
 .../thisAsExtensionReceiver.fir.kt            |  15 +
 .../usingOuterInstance.fir.kt                 |   8 +
 .../usingOuterProperty.fir.kt                 |   8 +
 .../headerSupertypeInitialization.fir.kt      |   5 +
 .../implicitSuperCallErrorsIfPrimary.fir.kt   |   7 +
 .../initializationFromOtherInstance.fir.kt    |  15 +
 .../tests/secondaryConstructors/kt6992.fir.kt |   3 +
 .../tests/secondaryConstructors/kt6993.fir.kt |   5 +
 .../tests/secondaryConstructors/kt6994.fir.kt |   4 +
 .../lambdaInDelegation.fir.kt                 |   5 +
 .../nestedExtendsInner.fir.kt                 |   7 +
 .../noDefaultIfEmptySecondary.fir.kt          |   4 +
 .../noPrimaryConstructor.fir.kt               |   6 +
 ...ertypeInitWithSecondaryConstructors.fir.kt |   6 +
 .../propertyInitializationWithPrimary.fir.kt  |  33 ++
 ...ropertyInitializationWithoutPrimary.fir.kt |  39 ++
 .../redeclarations.fir.kt                     |  27 ++
 ...redeclarationsOfConstructorsIgnored.fir.kt |  11 +
 ...reportResolutionErrorOnImplicitOnce.fir.kt |   6 +
 ...vePropertyInitializerWithoutPrimary.fir.kt |   4 +
 .../tests/secondaryConstructors/return.fir.kt |  17 +
 .../superAnyNonEmpty.fir.kt                   |   4 +
 .../superSecondaryNonExisting.fir.kt          |  10 +
 .../thisNonExisting.fir.kt                    |   8 +
 .../unreachableCode.fir.kt                    |  38 ++
 .../useOfPropertiesWithPrimary.fir.kt         |  30 ++
 .../useOfPropertiesWithoutPrimary.fir.kt      |  46 +++
 .../valOrValAndModifiersInCtr.fir.kt          |   7 +
 .../varargsInDelegationCallToPrimary.fir.kt   |  12 +
 .../varargsInDelegationCallToSecondary.fir.kt |  17 +
 .../senselessComparison/noExplicitType.fir.kt |  15 +
 .../senselessComparison/parenthesized.fir.kt  |  23 ++
 .../shadowing/ShadowLambdaParameter.fir.kt    |  13 +
 ...dowMultiDeclarationWithFunParameter.fir.kt |  14 +
 .../ShadowParameterInFunctionBody.fir.kt      |   4 +
 .../ShadowParameterInNestedBlockInFor.fir.kt  |   7 +
 .../shadowing/ShadowPropertyInClosure.fir.kt  |   3 +
 .../shadowing/ShadowPropertyInFor.fir.kt      |  11 +
 .../shadowing/ShadowPropertyInFunction.fir.kt |  10 +
 .../shadowing/ShadowVariableInFor.fir.kt      |   6 +
 .../ShadowVariableInNestedBlock.fir.kt        |   7 +
 .../ShadowVariableInNestedClosure.fir.kt      |   5 +
 .../ShadowVariableInNestedClosureParam.fir.kt |   5 +
 .../noNameShadowingForSimpleParameters.fir.kt |  24 ++
 .../tests/smartCasts/afterBinaryExpr.fir.kt   |  14 +
 .../tests/smartCasts/alwaysNull.fir.kt        |  23 ++
 .../smartCasts/alwaysNullWithJava.fir.kt      |  17 +
 .../smartCasts/castchecks/basicOff.fir.kt     |  36 ++
 .../smartCasts/castchecks/basicOn.fir.kt      |  36 ++
 .../smartCasts/castchecks/impossible.fir.kt   |  25 ++
 .../smartCasts/castchecks/insideCall.fir.kt   |  13 +
 ...fNullableExpressionWithExpectedType.fir.kt |   9 +
 .../smartCasts/castchecks/variables.fir.kt    |  68 ++++
 .../tests/smartCasts/classObjectMember.fir.kt |  22 ++
 .../combineWithNoSelectorInfo.fir.kt          |  13 +
 .../smartCasts/comparisonUnderAnd.fir.kt      |  39 ++
 .../tests/smartCasts/complexComparison.fir.kt |  23 ++
 .../complexConditionsWithExcl.fir.kt          |  55 +++
 .../dataFlowInfoForArguments.fir.kt           |   7 +
 .../smartCasts/doubleLambdaArgument.fir.kt    |  10 +
 .../tests/smartCasts/elvis/basicOff.fir.kt    |  50 +++
 .../tests/smartCasts/elvis/basicOn.fir.kt     |  50 +++
 .../tests/smartCasts/elvis/impossible.fir.kt  |  41 ++
 .../tests/smartCasts/elvisExclExcl.fir.kt     |   9 +
 .../smartCasts/elvisExclExclMerge.fir.kt      |   6 +
 .../smartCasts/elvisExclExclPlatform.fir.kt   |  27 ++
 .../tests/smartCasts/elvisExprNotNull.fir.kt  |  37 ++
 .../tests/smartCasts/elvisNothingRHS.fir.kt   |  11 +
 .../tests/smartCasts/elvisRHS.fir.kt          |  10 +
 .../smartCasts/enumEntryMembers_after.fir.kt  |  19 +
 .../smartCasts/enumEntryMembers_before.fir.kt |  19 +
 .../tests/smartCasts/equals.fir.kt            |  25 ++
 .../tests/smartCasts/exclUnderAnd.fir.kt      |  13 +
 .../smartCasts/explicitDefaultGetter.fir.kt   |  12 +
 .../tests/smartCasts/extensionSafeCall.fir.kt |  13 +
 .../smartCasts/fakeSmartCastOnEquality.fir.kt |  95 +++++
 .../smartCasts/falseReceiverSmartCast.fir.kt  |  15 +
 .../smartCasts/falseUnnecessaryCall.fir.kt    |  11 +
 .../tests/smartCasts/fieldExclExcl.fir.kt     |  12 +
 .../tests/smartCasts/fieldInGetter.fir.kt     |   5 +
 .../tests/smartCasts/fieldPlus.fir.kt         |  14 +
 .../smartCasts/genericIntersection.fir.kt     |   7 +
 .../tests/smartCasts/genericSet.fir.kt        |   7 +
 .../smartCasts/ifCascadeExprNotNull.fir.kt    |  14 +
 .../ifExprInConditionNonNull.fir.kt           |  11 +
 .../ifExprInWhenSubjectNonNull.fir.kt         |  11 +
 .../tests/smartCasts/ifExprNonNull.fir.kt     |  19 +
 .../tests/smartCasts/ifWhenExprNonNull.fir.kt |  13 +
 .../tests/smartCasts/implicitReceiver.fir.kt  |  29 ++
 .../smartCasts/implicitToGrandSon.fir.kt      |  11 +
 .../tests/smartCasts/incDecToNull.fir.kt      |  10 +
 .../inference/dependentOnPrevArg.fir.kt       |   7 +
 .../inference/intersectionTypes.fir.kt        |  61 +++
 .../tests/smartCasts/inference/kt1275.fir.kt  |  11 +
 .../tests/smartCasts/inference/kt1355.fir.kt  |  40 ++
 .../tests/smartCasts/inference/kt25432.fir.kt |  11 +
 .../tests/smartCasts/inference/kt2746.fir.kt  |  18 +
 .../tests/smartCasts/inference/kt2851.fir.kt  |  20 +
 .../tests/smartCasts/inference/kt29767.fir.kt |  11 +
 .../tests/smartCasts/inference/kt4009.fir.kt  |  22 ++
 .../tests/smartCasts/inference/kt4403.fir.kt  |  11 +
 .../tests/smartCasts/inference/kt4415.fir.kt  |  17 +
 .../tests/smartCasts/inference/kt6242.fir.kt  |  12 +
 .../inference/smartCastOnReceiver.fir.kt      |  13 +
 .../conflictTypeParameters.fir.kt             |  13 +
 .../conflictingReturnType.fir.kt              |  15 +
 .../intersectionScope/flexibleTypes.fir.kt    |  53 +++
 .../moreSpecificSetter.fir.kt                 |  15 +
 .../moreSpecificVisibility.fir.kt             |  16 +
 .../intersectionScope/mostSpecific.fir.kt     |  19 +
 .../mostSpecificIrrelevant.fir.kt             |  15 +
 .../intersectionScope/properties.fir.kt       |  21 +
 .../propertiesConflict.fir.kt                 |  20 +
 .../intersectionScope/refineReturnType.fir.kt |  16 +
 .../intersectionScope/simple.fir.kt           |  12 +
 .../unstableSmartCast.fir.kt                  |  38 ++
 .../validTypeParameters.fir.kt                |  15 +
 .../validTypeParametersNoSmartCast.fir.kt     |  15 +
 .../tests/smartCasts/kt10232.fir.kt           |  15 +
 .../tests/smartCasts/kt10444.fir.kt           |  35 ++
 .../tests/smartCasts/kt10483.fir.kt           |  17 +
 .../tests/smartCasts/kt1461.fir.kt            |  18 +
 .../tests/smartCasts/kt2422.fir.kt            |  23 ++
 .../tests/smartCasts/kt27221.fir.kt           |  28 ++
 .../tests/smartCasts/kt27221_2.fir.kt         |  36 ++
 .../kt27221_irrelevantClasses.fir.kt          |  28 ++
 .../tests/smartCasts/kt2865.fir.kt            |  12 +
 .../tests/smartCasts/kt30826.fir.kt           |  19 +
 .../tests/smartCasts/kt30927.fir.kt           |  51 +++
 .../tests/smartCasts/kt3224.fir.kt            |   8 +
 .../tests/smartCasts/kt3244.fir.kt            |  12 +
 .../tests/smartCasts/kt3572.fir.kt            |  17 +
 .../tests/smartCasts/kt3711.fir.kt            |   9 +
 .../tests/smartCasts/kt3899.fir.kt            |  13 +
 .../tests/smartCasts/kt3993.fir.kt            |  10 +
 .../tests/smartCasts/kt5427.fir.kt            |   5 +
 .../tests/smartCasts/kt5455.fir.kt            |  28 ++
 .../tests/smartCasts/kt6819.fir.kt            |   7 +
 .../tests/smartCasts/kt7561.fir.kt            |  15 +
 .../tests/smartCasts/lambdaAndArgument.fir.kt |  14 +
 .../smartCasts/lambdaAndArgumentFun.fir.kt    |  14 +
 .../lambdaArgumentNoSubstitutedReturn.fir.kt  |  19 +
 .../lambdaArgumentWithBoundWithoutType.fir.kt |  26 ++
 ...mbdaArgumentWithExpectedGenericType.fir.kt |   8 +
 .../lambdaArgumentWithoutType.fir.kt          |  20 +
 .../lambdaArgumentWithoutTypeIf.fir.kt        |  13 +
 .../lambdaArgumentWithoutTypeIfMerge.fir.kt   |  14 +
 .../lambdaArgumentWithoutTypeWhen.fir.kt      |  13 +
 .../tests/smartCasts/lambdaCall.fir.kt        |   6 +
 .../smartCasts/lambdaCallAnnotated.fir.kt     |  11 +
 .../lambdaDeclaresAndModifies.fir.kt          |   8 +
 .../lambdaDeclaresAndModifiesInLoop.fir.kt    |  10 +
 ...ambdaDeclaresAndModifiesInSecondary.fir.kt |  10 +
 ...mbdaDeclaresAndModifiesWithDirectEq.fir.kt |  20 +
 .../smartCasts/lambdaUsesOwnerModifies.fir.kt |  10 +
 .../tests/smartCasts/level_1_0.fir.kt         |  52 +++
 .../tests/smartCasts/localClassChanges.fir.kt |  15 +
 .../localDelegatedPropertyAfter.fir.kt        |  15 +
 .../localDelegatedPropertyBefore.fir.kt       |  15 +
 .../tests/smartCasts/localFunBetween.fir.kt   |  15 +
 .../tests/smartCasts/localFunChanges.fir.kt   |  15 +
 .../smartCasts/localObjectChanges.fir.kt      |  15 +
 .../WhileTrueWithBreakInIfCondition.fir.kt    |  13 +
 .../assignElvisIfBreakInsideWhileTrue.fir.kt  |  11 +
 .../loops/assignWhenInsideWhileTrue.fir.kt    |  17 +
 .../callBreakBetweenInsideDoWhile.fir.kt      |  16 +
 .../loops/callBreakFirstInsideDoWhile.fir.kt  |  13 +
 .../loops/callBreakInsideDoWhile.fir.kt       |  14 +
 .../loops/callBreakSecondInsideDoWhile.fir.kt |  13 +
 .../loops/callBreakThirdInsideDoWhile.fir.kt  |  16 +
 .../tests/smartCasts/loops/doWhile.fir.kt     |  11 +
 .../smartCasts/loops/doWhileBreak.fir.kt      |  11 +
 .../smartCasts/loops/doWhileContinue.fir.kt   |  11 +
 .../smartCasts/loops/doWhileEarlyBreak.fir.kt |  13 +
 .../loops/doWhileEarlyContinue.fir.kt         |  13 +
 .../loops/doWhileInCondition.fir.kt           |   5 +
 .../loops/doWhileInConditionWithBreak.fir.kt  |   9 +
 .../smartCasts/loops/doWhileLiteral.fir.kt    |  10 +
 .../loops/doWhileNotNullBreak.fir.kt          |  10 +
 .../tests/smartCasts/loops/doWhileNull.fir.kt |   5 +
 .../loops/doWhileNullWithBreak.fir.kt         |   9 +
 .../loops/elvisBreakInsideDoWhile.fir.kt      |  10 +
 .../loops/elvisIfBreakInsideWhileTrue.fir.kt  |   9 +
 .../loops/elvisInsideDoWhile.fir.kt           |   9 +
 .../elvisLeftBreakInsideWhileTrue.fir.kt      |   9 +
 .../loops/ifBlockInsideDoWhile.fir.kt         |  12 +
 .../loops/ifBreakAssignInsideDoWhile.fir.kt   |  14 +
 .../loops/ifBreakAssignInsideWhileTrue.fir.kt |  10 +
 .../loops/ifBreakExprInsideWhileTrue.fir.kt   |  10 +
 .../loops/ifElseBlockInsideDoWhile.fir.kt     |  15 +
 .../smartCasts/loops/ifInsideDoWhile.fir.kt   |   9 +
 .../leftElvisBreakInsideWhileTrue.fir.kt      |  11 +
 .../smartCasts/loops/nestedDoWhile.fir.kt     |  13 +
 .../nestedDoWhileWithLongContinue.fir.kt      |  14 +
 .../tests/smartCasts/loops/nestedLoops.fir.kt |  17 +
 .../smartCasts/loops/nestedLoopsShort.fir.kt  |  15 +
 .../loops/nestedLoopsWithBreak.fir.kt         |  18 +
 .../loops/nestedLoopsWithLongBreak.fir.kt     |  20 +
 .../loops/nestedLoopsWithLongContinue.fir.kt  |  19 +
 .../loops/plusAssignWhenInsideDoWhile.fir.kt  |  22 ++
 .../loops/safeCallBreakInsideDoWhile.fir.kt   |  14 +
 .../loops/safeCallInsideDoWhile.fir.kt        |  12 +
 .../smartCasts/loops/useInsideDoWhile.fir.kt  |   9 +
 .../loops/whenInsideWhileTrue.fir.kt          |  12 +
 .../loops/whenReturnInsideWhileTrue.fir.kt    |  13 +
 .../smartCasts/loops/whileInCondition.fir.kt  |   6 +
 .../loops/whileInConditionWithBreak.fir.kt    |   9 +
 .../tests/smartCasts/loops/whileNull.fir.kt   |   5 +
 .../loops/whileNullAssignToSomething.fir.kt   |   9 +
 .../loops/whileNullWithBreak.fir.kt           |   9 +
 .../tests/smartCasts/loops/whileSimple.fir.kt |  10 +
 .../smartCasts/loops/whileTrivial.fir.kt      |  11 +
 .../tests/smartCasts/loops/whileTrue.fir.kt   |  12 +
 .../loops/whileTrueBreakReturn.fir.kt         |  12 +
 .../loops/whileTrueEarlyBreak.fir.kt          |  11 +
 .../smartCasts/loops/whileTrueReturn.fir.kt   |  13 +
 ...eWithAssertInConditionAndBreakAfter.fir.kt |  23 ++
 ...WithAssertInConditionAndBreakBefore.fir.kt |  21 +
 .../smartCasts/multipleResolvedCalls.fir.kt   |  19 +
 .../noErrorCheckForPackageLevelVal.fir.kt     |  25 ++
 .../noUnnecessarySmartCastForReceiver.fir.kt  |   7 +
 .../tests/smartCasts/notNullorNotNull.fir.kt  |   6 +
 .../objectLiterals/assignment.fir.kt          |  19 +
 .../smartCasts/objectLiterals/base.fir.kt     |  19 +
 .../smartCasts/objectLiterals/captured.fir.kt |  23 ++
 .../smartCasts/objectLiterals/exclexcl.fir.kt |  22 ++
 .../objectLiterals/exclexclArgument.fir.kt    |  17 +
 .../objectLiterals/exclexclTwoArgument.fir.kt |  21 +
 .../smartCasts/objectLiterals/kt7110.fir.kt   |  11 +
 .../smartCasts/objectLiterals/receiver.fir.kt |  16 +
 .../tests/smartCasts/openInSealed.fir.kt      |   8 +
 .../ownerDeclaresBothModifies.fir.kt          |  13 +
 .../smartCasts/propertyAsCondition.fir.kt     |  30 ++
 .../tests/smartCasts/propertyToNotNull.fir.kt |  14 +
 .../smartCasts/publicVals/customGetter.fir.kt |  13 +
 .../smartCasts/publicVals/delegate.fir.kt     |  24 ++
 .../tests/smartCasts/publicVals/kt4409.fir.kt |  13 +
 .../tests/smartCasts/publicVals/kt5502.fir.kt |  16 +
 .../tests/smartCasts/publicVals/open.fir.kt   |  11 +
 .../smartCasts/publicVals/otherModule.fir.kt  |  35 ++
 .../smartCasts/publicVals/protected.fir.kt    |  17 +
 .../tests/smartCasts/publicVals/simple.fir.kt |  12 +
 .../tests/smartCasts/publicVals/var.fir.kt    |  15 +
 .../tests/smartCasts/safeAs.fir.kt            |  17 +
 .../smartCasts/safecalls/anotherVal.fir.kt    |   8 +
 .../smartCasts/safecalls/argument.fir.kt      |   6 +
 .../smartCasts/safecalls/chainAndUse.fir.kt   |   6 +
 .../smartCasts/safecalls/chainInChain.fir.kt  |   6 +
 .../safecalls/chainMixedUnsafe.fir.kt         |   5 +
 .../smartCasts/safecalls/doubleCall.fir.kt    |   6 +
 .../smartCasts/safecalls/extension.fir.kt     |   6 +
 .../smartCasts/safecalls/extensionCall.fir.kt |   6 +
 .../smartCasts/safecalls/falseArgument.fir.kt |   7 +
 .../smartCasts/safecalls/falseChain.fir.kt    |   4 +
 .../safecalls/falseExtension.fir.kt           |   7 +
 .../safecalls/falseSecondArgument.fir.kt      |   7 +
 .../smartCasts/safecalls/innerReceiver.fir.kt |   8 +
 .../smartCasts/safecalls/insideCall.fir.kt    |   8 +
 .../smartCasts/safecalls/insideIfExpr.fir.kt  |  43 ++
 .../smartCasts/safecalls/longChain.fir.kt     |   6 +
 .../safecalls/nullableReceiver.fir.kt         |  13 +
 .../nullableReceiverInLongChain.fir.kt        |  42 ++
 .../nullableReceiverWithExclExcl.fir.kt       |  11 +
 .../nullableReceiverWithFlexible.fir.kt       |  25 ++
 .../smartCasts/safecalls/property.fir.kt      |   6 +
 .../smartCasts/safecalls/propertyChain.fir.kt |  14 +
 .../smartCasts/safecalls/receiver.fir.kt      |   8 +
 .../safecalls/receiverAndChain.fir.kt         |   8 +
 .../safecalls/receiverAndChainFalse.fir.kt    |  10 +
 .../safeAccessReceiverNotNull.fir.kt          | 136 +++++++
 .../tests/smartCasts/safecalls/simple.fir.kt  |   6 +
 .../safecalls/simpleNullableReceiver.fir.kt   |   6 +
 .../tests/smartCasts/safecalls/twoArgs.fir.kt |   6 +
 .../severalSmartCastsOnReified.fir.kt         |  11 +
 .../smartCasts/shortIfExprNotNull.fir.kt      |   9 +
 .../smartCastAndArgumentApproximation.fir.kt  |   8 +
 .../tests/smartCasts/smartCastOnElvis.fir.kt  |  15 +
 .../tests/smartCasts/smartCastOnIf.fir.kt     |  10 +
 .../tests/smartCasts/smartCastOnWhen.fir.kt   |  20 +
 ...castOnSameFieldOfDifferentInstances.fir.kt |  11 +
 .../tests/smartCasts/thisWithLabel.fir.kt     |  36 ++
 .../thisWithLabelAsReceiverPart.fir.kt        |  39 ++
 .../smartCasts/threeImplicitReceivers.fir.kt  |  27 ++
 .../smartCasts/twoImplicitReceivers.fir.kt    |  18 +
 .../tests/smartCasts/typeDegradation.fir.kt   |  17 +
 .../tests/smartCasts/typeInComparison.fir.kt  |   9 +
 .../tests/smartCasts/unstableToStable.fir.kt  |  18 +
 .../smartCasts/unstableToStableTypes.fir.kt   |  22 ++
 .../smartCasts/varChangedInInitializer.fir.kt |   7 +
 .../varChangedInLocalInitializer.fir.kt       |  10 +
 .../tests/smartCasts/varInAccessor.fir.kt     |  17 +
 .../smartCasts/varInInitNoPrimary.fir.kt      |  22 ++
 .../tests/smartCasts/varInInitializer.fir.kt  |  12 +
 .../varInSecondaryConstructor.fir.kt          |  10 +
 .../tests/smartCasts/varInsideLocalFun.fir.kt |  17 +
 .../variables/accessorAndFunction.fir.kt      |  23 ++
 .../smartCasts/variables/assignment.fir.kt    |  10 +
 .../variables/assignmentConversion.fir.kt     |  35 ++
 .../variables/doWhileWithMiddleBreak.fir.kt   |  12 +
 .../variables/ifElseBlockInsideDoWhile.fir.kt |  15 +
 .../ifElseBlockInsideDoWhileWithBreak.fir.kt  |  16 +
 .../variables/ifNullAssignment.fir.kt         |  73 ++++
 .../tests/smartCasts/variables/ifVarIs.fir.kt |   9 +
 .../smartCasts/variables/ifVarIsAnd.fir.kt    |  13 +
 .../variables/ifVarIsChanged.fir.kt           |  11 +
 .../smartCasts/variables/inPropertySam.fir.kt |  18 +
 .../tests/smartCasts/variables/infix.fir.kt   |  11 +
 .../variables/initialization.fir.kt           |   8 +
 .../tests/smartCasts/variables/kt7599.fir.kt  |  23 ++
 .../variables/lambdaBetweenArguments.fir.kt   |  10 +
 .../smartCasts/variables/property.fir.kt      |  11 +
 .../variables/propertyNotNeeded.fir.kt        |  10 +
 .../variables/propertySubtype.fir.kt          |  10 +
 .../variables/propertySubtypeInMember.fir.kt  |  10 +
 .../propertySubtypeInMemberCheck.fir.kt       |  13 +
 .../smartCasts/variables/varAsUse.fir.kt      |   9 +
 .../variables/varChangedInLoop.fir.kt         |   9 +
 .../variables/varNotChangedInLoop.fir.kt      |   8 +
 .../smartCasts/variables/whileTrue.fir.kt     |  13 +
 .../variables/whileWithBreak.fir.kt           |  17 +
 .../varnotnull/assignNestedWhile.fir.kt       |  28 ++
 .../smartCasts/varnotnull/assignment.fir.kt   |  11 +
 .../varnotnull/boundInitializer.fir.kt        |  20 +
 .../varnotnull/boundInitializerWrong.fir.kt   |  46 +++
 .../capturedInClosureModifiedBefore.fir.kt    |  60 +++
 .../varnotnull/capturedInClosureOff.fir.kt    |  15 +
 .../varnotnull/doWhileWithBreak.fir.kt        |  21 +
 .../varnotnull/doWhileWithMiddleBreak.fir.kt  |  12 +
 .../smartCasts/varnotnull/forEach.fir.kt      |  17 +
 .../varnotnull/forEachWithBreak.fir.kt        |  18 +
 .../varnotnull/forEachWithContinue.fir.kt     |  18 +
 .../smartCasts/varnotnull/ifVarNotNull.fir.kt |   9 +
 .../varnotnull/ifVarNotNullAnd.fir.kt         |  13 +
 .../varnotnull/ifVarNullElse.fir.kt           |  12 +
 .../varnotnull/ifVarNullReturn.fir.kt         |  11 +
 .../smartCasts/varnotnull/inference.fir.kt    |  21 +
 .../varnotnull/infiniteWhileWithBreak.fir.kt  |  20 +
 .../tests/smartCasts/varnotnull/infix.fir.kt  |  11 +
 .../varnotnull/initInTryReturnInCatch.fir.kt  |  80 ++++
 .../varnotnull/initialization.fir.kt          |   8 +
 .../smartCasts/varnotnull/iterations.fir.kt   |  14 +
 .../varnotnull/nestedDoWhile.fir.kt           |  15 +
 .../smartCasts/varnotnull/nestedLoops.fir.kt  |  19 +
 .../smartCasts/varnotnull/nestedWhile.fir.kt  |  27 ++
 .../varnotnull/plusplusMinusminus.fir.kt      |  21 +
 .../postfixNotnullClassIncrement.fir.kt       |  13 +
 .../postfixNullableClassIncrement.fir.kt      |  12 +
 .../postfixNullableIncrement.fir.kt           |   8 +
 .../prefixNotnullClassIncrement.fir.kt        |  13 +
 .../prefixNullableClassIncrement.fir.kt       |  13 +
 .../varnotnull/prefixNullableIncrement.fir.kt |   8 +
 .../varnotnull/setNotNullInTry.fir.kt         |  14 +
 .../smartCasts/varnotnull/setNullInTry.fir.kt |  10 +
 .../varnotnull/setNullInTryFinally.fir.kt     |  16 +
 .../varnotnull/setNullInTryUnsound.fir.kt     |  10 +
 .../smartCasts/varnotnull/setSameInTry.fir.kt |  11 +
 .../varnotnull/toFlexibleType.fir.kt          |  16 +
 .../smartCasts/varnotnull/unnecessary.fir.kt  |  12 +
 .../varnotnull/unnecessaryWithBranch.fir.kt   |  12 +
 .../varnotnull/unnecessaryWithMap.fir.kt      |  20 +
 .../varnotnull/varCapturedInClosure.fir.kt    |  17 +
 .../varCapturedInInlineClosure.fir.kt         |  16 +
 .../varCapturedInSafeClosure.fir.kt           |  15 +
 .../varnotnull/varChangedInLoop.fir.kt        |   9 +
 .../smartCasts/varnotnull/varCheck.fir.kt     |   9 +
 .../smartCasts/varnotnull/varIntNull.fir.kt   |   6 +
 .../varnotnull/varNotChangedInLoop.fir.kt     |   8 +
 .../smartCasts/varnotnull/varNull.fir.kt      |   6 +
 .../smartCasts/varnotnull/whileTrue.fir.kt    |  13 +
 .../varnotnull/whileTrueWithBracketSet.fir.kt |  13 +
 .../varnotnull/whileTrueWithBrackets.fir.kt   |  13 +
 .../varnotnull/whileWithBreak.fir.kt          |  17 +
 .../tests/smartCasts/whenExprNonNull.fir.kt   |  18 +
 .../tests/smartCasts/whenIfExprNonNull.fir.kt |  13 +
 .../smartCasts/whenSubjectImpossible.fir.kt   |  10 +
 .../whenSubjectImpossibleJava.fir.kt          |  11 +
 .../apiVersion/annotations.fir.kt             |  11 +
 .../apiVersion/classesAndConstructors.fir.kt  |  23 ++
 .../apiVersion/overriddenMembers.fir.kt       |  34 ++
 .../apiVersion/propertyAccessors.fir.kt       |  48 +++
 .../apiVersion/simpleMembers.fir.kt           |  19 +
 .../apiVersion/sinceOldVersionIsOK.fir.kt     |  18 +
 .../typealiasesAsCompanionObjects.fir.kt      |  15 +
 .../typealiasesAsConstructors.fir.kt          |  20 +
 .../apiVersion/typealiasesAsObjects.fir.kt    |  11 +
 .../apiVersion/typealiasesAsTypes.fir.kt      |  21 +
 .../apiVersion/typealiasesOnImport.fir.kt     |  18 +
 .../inlineFunctionAlways.fir.kt               |  16 +
 .../noBigFunctionTypes.fir.kt                 |  20 +
 .../boundCallableReference.fir.kt             |  25 ++
 .../boundClassLiteral.fir.kt                  |  18 +
 ...edJavaClassLiteralInKClassExtension.fir.kt |  11 +
 ...JavaClassReferenceInKClassExtension.fir.kt |  10 +
 .../noCallableReferencesWithEmptyLHS.fir.kt   |  28 ++
 .../noDataClassInheritance.fir.kt             |  23 ++
 .../noInlineProperty.fir.kt                   |  11 +
 .../noLocalDelegatedProperty.fir.kt           |  21 +
 .../noMultiplatformProjects.fir.kt            |   7 +
 .../noTopLevelSealedInheritance.fir.kt        |   5 +
 .../tests/substitutions/kt1558-short.fir.kt   |   5 +
 .../tests/substitutions/kt4887.fir.kt         |   8 +
 .../substitutions/starProjections.fir.kt      |  25 ++
 ...nForOverloadResolutionWithAmbiguity.fir.kt |  19 +
 ...ForOverloadResolutionWithErrorTypes.fir.kt |   9 +
 .../extFunctionTypeAsSuperType.fir.kt         |  24 ++
 .../findClosestCorrespondingSupertype.fir.kt  |  10 +
 .../subtyping/functionTypeAsSuperType.fir.kt  |  45 +++
 ...tForTypeParameterWithMultipleBounds.fir.kt |  18 +
 .../subtyping/javaAndKotlinSuperType.fir.kt   |  42 ++
 .../tests/subtyping/kt-1457.fir.kt            |  12 +
 .../diagnostics/tests/subtyping/kt2069.fir.kt |  14 +
 .../diagnostics/tests/subtyping/kt2744.fir.kt |   3 +
 .../diagnostics/tests/subtyping/kt304.fir.kt  |   7 +
 .../diagnostics/tests/subtyping/kt3159.fir.kt |   9 +
 .../subtyping/localAnonymousObjects.fir.kt    |   5 +
 .../tests/subtyping/localClasses.fir.kt       |  19 +
 .../subtyping/memberAnonymousObjects.fir.kt   |   6 +
 .../subtyping/nestedIntoLocalClasses.fir.kt   |  23 ++
 .../tests/subtyping/nestedLocalClasses.fir.kt |  23 ++
 .../subtyping/topLevelAnonymousObjects.fir.kt |   5 +
 .../subtyping/unresolvedSupertype.fir.kt      |   7 +
 ...WarningsOnAnonymousObjectInVariable.fir.kt |   4 +
 .../suppressWarningsOnClass.fir.kt            |   7 +
 .../suppressWarningsOnClassObject.fir.kt      |   6 +
 .../suppressWarningsOnExpression.fir.kt       |   4 +
 .../allWarnings/suppressWarningsOnFile.fir.kt |   7 +
 .../suppressWarningsOnFunction.fir.kt         |   4 +
 .../suppressWarningsOnObject.fir.kt           |   4 +
 .../suppressWarningsOnParameter.fir.kt        |   3 +
 .../suppressWarningsOnProperty.fir.kt         |   4 +
 .../suppressWarningsOnPropertyAccessor.fir.kt |   5 +
 .../tests/suppress/manyWarnings/mixed.fir.kt  |   5 +
 .../suppress/manyWarnings/onClass.fir.kt      |   4 +
 .../manyWarnings/onClassObject.fir.kt         |   6 +
 .../suppress/manyWarnings/onExpression.fir.kt |   4 +
 .../suppress/manyWarnings/onFunction.fir.kt   |   4 +
 .../suppress/manyWarnings/onObject.fir.kt     |   4 +
 .../suppress/manyWarnings/onParameter.fir.kt  |   3 +
 .../suppress/manyWarnings/onProperty.fir.kt   |   4 +
 .../manyWarnings/onPropertyAccessor.fir.kt    |   5 +
 .../oneWarning/onBlockStatement.fir.kt        |  60 +++
 .../onBlockStatementSameLine.fir.kt           |  19 +
 .../tests/suppress/oneWarning/onClass.fir.kt  |   4 +
 .../suppress/oneWarning/onClassObject.fir.kt  |   6 +
 .../suppress/oneWarning/onExpression.fir.kt   |   4 +
 .../suppress/oneWarning/onFunction.fir.kt     |   4 +
 .../oneWarning/onLocalVariable.fir.kt         |   7 +
 .../tests/suppress/oneWarning/onObject.fir.kt |   4 +
 .../suppress/oneWarning/onParameter.fir.kt    |   3 +
 .../suppress/oneWarning/onProperty.fir.kt     |   4 +
 .../oneWarning/onPropertyAccessor.fir.kt      |   5 +
 .../javaProperties/AbbreviationName.fir.kt    |  20 +
 .../javaProperties/Bases.fir.kt               |  31 ++
 .../javaProperties/CompiledClass.fir.kt       |   6 +
 .../javaProperties/Deprecated.fir.kt          |  48 +++
 .../javaProperties/FalseGetters.fir.kt        |  21 +
 .../javaProperties/FalseSetters.fir.kt        |  26 ++
 .../javaProperties/FromTwoBases.fir.kt        |  19 +
 .../javaProperties/GenericClass.fir.kt        |  10 +
 .../javaProperties/GetA.fir.kt                |  10 +
 .../javaProperties/Getter.fir.kt              |  20 +
 .../javaProperties/GetterAndSetter.fir.kt     |  14 +
 .../javaProperties/ImplicitReceiver.fir.kt    |  12 +
 .../javaProperties/IsNaming.fir.kt            |  37 ++
 .../javaProperties/JavaOverridesKotlin.fir.kt |  29 ++
 .../javaProperties/KotlinOverridesJava.fir.kt |  52 +++
 .../KotlinOverridesJava2.fir.kt               |  25 ++
 .../KotlinOverridesJava3.fir.kt               |  25 ++
 .../KotlinOverridesJava4.fir.kt               |  28 ++
 .../KotlinOverridesJava5.fir.kt               |  29 ++
 .../javaProperties/OnlyAscii.fir.kt           |  22 ++
 .../javaProperties/OnlyPublic.fir.kt          |  22 ++
 .../javaProperties/OverrideGetterOnly.fir.kt  |  22 ++
 .../SetterHasHigherAccess.fir.kt              |  16 +
 .../javaProperties/SetterOnly.fir.kt          |   9 +
 .../javaProperties/SmartCast.fir.kt           |  28 ++
 .../SmartCastImplicitReceiver.fir.kt          |  23 ++
 .../SyntheticJavaPropertyReference.fir.kt     |   9 +
 .../javaProperties/TypeAnnotation.fir.kt      |  13 +
 .../TypeParameterReceiver.fir.kt              |  16 +
 .../samAdapters/Deprecated.fir.kt             |  22 ++
 .../samAdapters/GenericClass.fir.kt           |  14 +
 .../samAdapters/GenericMethod.fir.kt          |  14 +
 .../GenericMethodInGenericClass.fir.kt        |  16 +
 .../samAdapters/InnerClassInGeneric.fir.kt    |  17 +
 .../samAdapters/NoNamedArgsAllowed.fir.kt     |  14 +
 .../samAdapters/PackageLocal.fir.kt           |  18 +
 .../ParameterTypeAnnotation.fir.kt            |  13 +
 .../samAdapters/PassNull.fir.kt               |  10 +
 .../samAdapters/Private.fir.kt                |  10 +
 .../samAdapters/Protected.fir.kt              |  24 ++
 .../samAdapters/ReturnTypeAnnotation.fir.kt   |  18 +
 .../samAdapters/Simple.fir.kt                 |  30 ++
 .../samAdapters/overloadResolution.fir.kt     |  36 ++
 .../overloadResolutionStatic.fir.kt           |  36 ++
 ...dResolutionStaticWithoutRefinedSams.fir.kt |  37 ++
 ...verloadResolutionWithoutRefinedSams.fir.kt |  37 ++
 .../tests/tailRecOnVirtualMember.fir.kt       | 171 ++++++++
 .../tests/tailRecOnVirtualMemberError.fir.kt  | 170 ++++++++
 .../tests/tailRecOverridden.fir.kt            |  32 ++
 .../tests/tailRecursionComplex.fir.kt         |  16 +
 .../backwardCompatibility/basic.fir.kt        |  18 +
 .../backwardCompatibility/delegation.fir.kt   |  32 ++
 .../derivedInterfaces.fir.kt                  |  13 +
 .../derivedInterfacesWithKotlinFun.fir.kt     |  15 +
 .../fillInStackTrace.fir.kt                   |   4 +
 .../backwardCompatibility/finalize.fir.kt     |  10 +
 .../hashMapGetOrDefault.fir.kt                |   6 +
 .../concurrentMapRemove.fir.kt                |  22 ++
 .../forEachRemainingNullability.fir.kt        |  41 ++
 .../targetedBuiltIns/getOrDefault.fir.kt      |  20 +
 .../targetedBuiltIns/mutableMapRemove.fir.kt  |  31 ++
 .../tests/targetedBuiltIns/removeIf.fir.kt    |  12 +
 .../tests/targetedBuiltIns/stream.fir.kt      |  13 +
 .../tests/thisAndSuper/QualifiedThis.fir.kt   |  12 +
 .../tests/thisAndSuper/Super.fir.kt           |  64 +++
 .../thisAndSuper/ambigousLabelOnThis.fir.kt   |   5 +
 .../genericQualifiedSuperOverridden.fir.kt    |  19 +
 .../thisAndSuper/implicitInvokeOnSuper.fir.kt |  15 +
 .../notAccessibleSuperInTrait.fir.kt          |  10 +
 .../qualifiedSuperOverridden.fir.kt           |  29 ++
 .../superInExtensionFunction.fir.kt           |   4 +
 .../superInExtensionFunctionCall.fir.kt       |   9 +
 .../superInToplevelFunction.fir.kt            |   5 +
 .../superIsNotAnExpression.fir.kt             |  12 +
 .../thisInFunctionLiterals.fir.kt             |  18 +
 .../thisAndSuper/thisInInnerClasses.fir.kt    |  11 +
 .../thisInPropertyInitializer.fir.kt          |   8 +
 .../thisInToplevelFunction.fir.kt             |   4 +
 .../tests/thisAndSuper/traitSuperCall.fir.kt  |  24 ++
 .../ambiguousSuperWithGenerics.fir.kt         |  38 ++
 .../unqualifiedSuper/unqualifiedSuper.fir.kt  |  57 +++
 ...unqualifiedSuperWithAbstractMembers.fir.kt |  39 ++
 ...nqualifiedSuperWithCallableProperty.fir.kt |  21 +
 ...qualifiedSuperWithDeeperHierarchies.fir.kt |  51 +++
 .../unqualifiedSuperWithGenerics.fir.kt       |  22 ++
 .../unqualifiedSuperWithInnerClass.fir.kt     |  33 ++
 .../unqualifiedSuperWithInterfaces.fir.kt     |  28 ++
 .../unqualifiedSuperWithLocalClass.fir.kt     |  21 +
 .../unqualifiedSuperWithUnresolvedBase.fir.kt |  53 +++
 ...withMethodOfAnyOverridenInInterface.fir.kt |   8 +
 ...hMethodOverriddenInAnotherSupertype.fir.kt |  29 ++
 .../unqualifiedSuper/withMethodsOfAny.fir.kt  |  10 +
 .../traitWithRequired/traitRequiresAny.fir.kt |   5 +
 .../traitSupertypeList.fir.kt                 |  10 +
 .../cannotHaveManyClassUpperBounds.fir.kt     |  18 +
 .../typeParameters/deprecatedSyntax.fir.kt    |   3 +
 .../extFunctionTypeAsUpperBound.fir.kt        |   7 +
 .../functionTypeAsUpperBound.fir.kt           |   7 +
 .../implicitNothingAsTypeParameter.fir.kt     | 103 +++++
 .../implicitNothingOnDelegates.fir.kt         |  23 ++
 .../misplacedConstraints.fir.kt               |  13 +
 .../propertyTypeParameters.fir.kt             |  44 +++
 ...opertyTypeParametersWithUpperBounds.fir.kt |  28 ++
 .../tests/typeParameters/repeatedBound.fir.kt |   7 +
 .../upperBoundCannotBeArray.fir.kt            |  18 +
 .../tests/typealias/aliasesOnly.fir.kt        |   8 +
 .../typealias/annotationsOnTypeAliases.fir.kt |  15 +
 ...oundViolationInTypeAliasConstructor.fir.kt |  18 +
 ...dsViolationInDeepTypeAliasExpansion.fir.kt |  17 +
 ...boundsViolationInTypeAliasExpansion.fir.kt |  30 ++
 .../boundsViolationInTypeAliasRHS.fir.kt      |  20 +
 ...pturingTypeParametersFromOuterClass.fir.kt |  29 ++
 .../tests/typealias/classReference.fir.kt     |   3 +
 .../typealias/conflictingProjections.fir.kt   |  16 +
 .../constructorCallThroughPrivateAlias.fir.kt |  29 ++
 .../cyclicInheritanceViaTypeAlias.fir.kt      |   7 +
 .../tests/typealias/enumEntryQualifier.fir.kt |   6 +
 .../typealias/exposedExpandedType.fir.kt      |  45 +++
 .../typealias/functionTypeInTypeAlias.fir.kt  |   3 +
 .../genericTypeAliasConstructor.fir.kt        |  10 +
 .../typealias/genericTypeAliasObject.fir.kt   |  25 ++
 .../illegalTypeInTypeAliasExpansion.fir.kt    |  12 +
 .../diagnostics/tests/typealias/import.fir.kt |  25 ++
 .../typealias/importForTypealiasObject.fir.kt |  18 +
 .../importFromTypeAliasObject.fir.kt          |  15 +
 .../importMemberFromJavaViaAlias.fir.kt       |  28 ++
 .../tests/typealias/inGenerics.fir.kt         |  12 +
 .../tests/typealias/inSupertypesList.fir.kt   |   6 +
 .../typealias/inheritedNestedTypeAlias.fir.kt |  20 +
 ...tedTypeAliasQualifiedByDerivedClass.fir.kt |  13 +
 .../innerClassTypeAliasConstructor.fir.kt     |  24 ++
 ...assTypeAliasConstructorInSupertypes.fir.kt |  40 ++
 .../typealias/innerTypeAliasAsType.fir.kt     |  34 ++
 .../typealias/innerTypeAliasAsType2.fir.kt    |  24 ++
 .../innerTypeAliasConstructor.fir.kt          |  24 ++
 .../tests/typealias/isAsWithTypeAlias.fir.kt  |   5 +
 .../javaStaticMembersViaTypeAlias.fir.kt      |  46 +++
 .../tests/typealias/kt14498.fir.kt            |  17 +
 .../tests/typealias/kt14498a.fir.kt           |  11 +
 .../tests/typealias/kt14518.fir.kt            |  10 +
 .../tests/typealias/kt14641.fir.kt            |  11 +
 .../tests/typealias/kt15734.fir.kt            |  19 +
 .../tests/typealias/kt19601.fir.kt            |  11 +
 .../tests/typealias/localTypeAlias.fir.kt     |  19 +
 .../localTypeAliasConstructor.fir.kt          |  11 +
 .../typealias/localTypeAliasModifiers.fir.kt  |   5 +
 .../typealias/localTypeAliasRecursive.fir.kt  |   7 +
 .../tests/typealias/methodReference.fir.kt    |   7 +
 .../diagnostics/tests/typealias/nested.fir.kt |  24 ++
 .../nestedCapturingTypeParameters.fir.kt      |  23 ++
 .../tests/typealias/nestedSubstituted.fir.kt  |   9 +
 ...tionInTypeAliasArgumentSubstitution.fir.kt |  17 +
 .../diagnostics/tests/typealias/noRHS.fir.kt  |   6 +
 .../typealias/parameterRestrictions.fir.kt    |   9 +
 .../typealias/parameterSubstitution.fir.kt    |   8 +
 .../tests/typealias/privateInFile.fir.kt      |  22 ++
 .../projectionsInTypeAliasConstructor.fir.kt  |   6 +
 .../tests/typealias/recursive.fir.kt          |  11 +
 ...eNothingShouldBeSpecifiedExplicitly.fir.kt |   5 +
 .../tests/typealias/simpleTypeAlias.fir.kt    |   8 +
 .../typealias/starImportOnTypeAlias.fir.kt    |  30 ++
 .../tests/typealias/starProjection.fir.kt     |  15 +
 .../starProjectionInTypeAliasArgument.fir.kt  |   6 +
 .../typealias/substitutionVariance.fir.kt     |  67 ++++
 .../tests/typealias/throwJLException.fir.kt   |   7 +
 .../typealias/topLevelTypeAliasesOnly.fir.kt  |  19 +
 ...typeAliasArgumentsInCompanionObject.fir.kt |  10 +
 .../typeAliasArgumentsInConstructor.fir.kt    |  11 +
 .../typealias/typeAliasAsBareType.fir.kt      |  35 ++
 .../typealias/typeAliasAsQualifier.fir.kt     |  21 +
 .../typeAliasAsSuperQualifier.fir.kt          |  41 ++
 .../typealias/typeAliasConstructor.fir.kt     |  24 ++
 ...ypeAliasConstructorCrazyProjections.fir.kt |  16 +
 .../typeAliasConstructorForInterface.fir.kt   |   6 +
 .../typeAliasConstructorForProjection.fir.kt  |  15 +
 ...onstructorForProjectionInSupertypes.fir.kt |  17 +
 .../typeAliasConstructorInSuperCall.fir.kt    |  14 +
 ...onstructorInferenceInSupertypesList.fir.kt |   7 +
 .../typeAliasConstructorReturnType.fir.kt     |  18 +
 ...asConstructorTypeArgumentsInference.fir.kt |  33 ++
 ...peArgumentsInferenceWithNestedCalls.fir.kt |   8 +
 ...eArgumentsInferenceWithNestedCalls2.fir.kt |  41 ++
 ...eArgumentsInferenceWithPhantomTypes.fir.kt |  17 +
 .../typeAliasConstructorVsFunction.fir.kt     |  14 +
 .../typeAliasConstructorWrongClass.fir.kt     |  34 ++
 ...typeAliasConstructorWrongVisibility.fir.kt |  29 ++
 ...peAliasExpansionRepeatedAnnotations.fir.kt |  16 +
 ...AliasForProjectionInSuperInterfaces.fir.kt |  32 ++
 .../typeAliasInAnonymousObjectType.fir.kt     |   5 +
 .../typealias/typeAliasInvisibleObject.fir.kt |   8 +
 .../tests/typealias/typeAliasNotNull.fir.kt   |   6 +
 .../tests/typealias/typeAliasObject.fir.kt    |  32 ++
 .../typeAliasObjectWithInvoke.fir.kt          |  24 ++
 .../typeAliasShouldExpandToClass.fir.kt       |  16 +
 .../typeAliasesInImportDirectives.fir.kt      |  47 +++
 .../typealias/typeAliasesInQualifiers.fir.kt  |  75 ++++
 .../typealias/typealiasRhsAnnotations.fir.kt  |  16 +
 .../typealiasRhsAnnotationsInArguments.fir.kt |  11 +
 ...iasRhsRepeatedAnnotationInArguments.fir.kt |   6 +
 .../typealiasRhsRepeatedAnnotations.fir.kt    |   4 +
 .../typealias/unsupportedTypeAlias.fir.kt     |  14 +
 .../typealias/unusedTypeAliasParameter.fir.kt |   2 +
 ...erOfArgumentsInTypeAliasConstructor.fir.kt |  42 ++
 .../illegalUnderscores.fir.kt                 |  17 +
 .../noUnderscores.fir.kt                      |   9 +
 .../tests/unit/nullableUnit.fir.kt            |   5 +
 ...roperDefaultInitializationInTailrec.fir.kt |  39 ++
 .../tests/varargs/AmbiguousVararg.fir.kt      |   6 +
 .../MoreSpecificVarargsOfEqualLength.fir.kt   |   9 +
 .../MostSepcificVarargsWithJava.fir.kt        |  19 +
 .../tests/varargs/NilaryVsVararg.fir.kt       |  10 +
 .../NullableTypeForVarargArgument.fir.kt      |  66 ++++
 .../tests/varargs/UnaryVsVararg.fir.kt        |   9 +
 ...gleArrayElementAsVarargInAnnotation.fir.kt |  26 ++
 ...rayElementAsVarargInAnnotationError.fir.kt |  26 ++
 ...signingArraysToVarargsInAnnotations.fir.kt |  46 +++
 ...entsInNamedFormAnnDeprecation_after.fir.kt |  30 ++
 ...ntsInNamedFormAnnDeprecation_before.fir.kt |  30 ++
 ...entsInNamedFormFunDeprecation_after.fir.kt |  60 +++
 ...ntsInNamedFormFunDeprecation_before.fir.kt |  60 +++
 .../diagnostics/tests/varargs/kt1781.fir.kt   |  13 +
 .../diagnostics/tests/varargs/kt1835.fir.kt   |  12 +
 .../tests/varargs/kt1838-param.fir.kt         |   5 +
 .../tests/varargs/kt1838-val.fir.kt           |   5 +
 .../diagnostics/tests/varargs/kt2163.fir.kt   |   7 +
 .../diagnostics/tests/varargs/kt422.fir.kt    |  17 +
 .../noAssigningArraysToVarargsFeature.fir.kt  |  49 +++
 ...tAssigningSingleElementsInNamedForm.fir.kt |  20 +
 .../tests/varargs/varargInSetter.fir.kt       |   6 +
 .../tests/varargs/varargIterator.fir.kt       |   5 +
 .../tests/varargs/varargOfNothing.fir.kt      |  15 +
 .../tests/varargs/varargViewedAsArray.fir.kt  |  29 ++
 .../varargs/varargsAndFunctionLiterals.fir.kt |  13 +
 .../tests/varargs/varargsAndOut1.fir.kt       |  13 +
 .../tests/varargs/varargsAndOut2.fir.kt       |   9 +
 .../tests/varargs/varargsAndPair.fir.kt       |  10 +
 .../diagnostics/tests/variance/Class.fir.kt   |  23 ++
 .../tests/variance/Function.fir.kt            |  34 ++
 .../tests/variance/FunctionTypes.fir.kt       |  12 +
 .../tests/variance/InPosition.fir.kt          |  48 +++
 .../tests/variance/InvariantPosition.fir.kt   |  45 +++
 .../tests/variance/NullableTypes.fir.kt       |  16 +
 .../tests/variance/OutPosition.fir.kt         |  40 ++
 .../tests/variance/PrimaryConstructor.fir.kt  |  25 ++
 .../tests/variance/ValProperty.fir.kt         |  50 +++
 .../tests/variance/VarProperty.fir.kt         |  50 +++
 .../tests/variance/Visibility.fir.kt          |  20 +
 .../tests/variance/ea1337846.fir.kt           |  21 +
 .../variance/privateToThis/Abstract.fir.kt    |   7 +
 .../privateToThis/FunctionCall.fir.kt         |  37 ++
 .../variance/privateToThis/GetVal.fir.kt      |  37 ++
 .../variance/privateToThis/SetVar.fir.kt      |  37 ++
 .../privateToThis/ValReassigned.fir.kt        |  20 +
 .../abstractInvisibleMemberFromJava.fir.kt    |  21 +
 .../abstractInvisibleMemberFromKotlin.fir.kt  |  47 +++
 ...actInvisibleMemberFromKotlinWarning.fir.kt |  22 ++
 .../tests/when/AnnotatedWhenStatement.fir.kt  |   8 +
 .../tests/when/BranchBypassVal.fir.kt         |  12 +
 .../tests/when/BranchBypassVar.fir.kt         |  12 +
 .../tests/when/BranchFalseBypass.fir.kt       |  12 +
 .../tests/when/BranchFalseBypassElse.fir.kt   |  12 +
 ...CommaInWhenConditionWithoutArgument.fir.kt |  11 +
 .../tests/when/DuplicatedLabels.fir.kt        |  51 +++
 .../tests/when/ElseOnNullableEnum.fir.kt      |  46 +++
 .../ElseOnNullableEnumWithSmartCast.fir.kt    |  11 +
 .../when/EmptyConditionWithExpression.fir.kt  |   8 +
 .../EmptyConditionWithExpressionEnum.fir.kt   |   9 +
 .../tests/when/ExhaustiveBoolean.fir.kt       |   8 +
 .../when/ExhaustiveBooleanBrackets.fir.kt     |   7 +
 .../when/ExhaustiveBooleanComplex.fir.kt      |   8 +
 .../when/ExhaustiveBooleanNullable.fir.kt     |   9 +
 .../tests/when/ExhaustiveBreakContinue.fir.kt |  14 +
 .../tests/when/ExhaustiveEnumIs.fir.kt        |  11 +
 .../tests/when/ExhaustiveEnumMixed.fir.kt     |  11 +
 .../when/ExhaustiveInitialization.fir.kt      |  15 +
 .../when/ExhaustiveNoInitialization.fir.kt    |  11 +
 .../tests/when/ExhaustiveNullable.fir.kt      |  14 +
 .../tests/when/ExhaustivePlatformEnum.fir.kt  |  21 +
 .../ExhaustivePlatformEnumAnnotated.fir.kt    |  23 ++
 .../when/ExhaustivePlatformEnumElse.fir.kt    |  21 +
 .../when/ExhaustivePlatformEnumNull.fir.kt    |  22 ++
 .../ExhaustivePlatformEnumStatement.fir.kt    |  20 +
 .../tests/when/ExhaustiveReturn.fir.kt        |  13 +
 .../tests/when/ExhaustiveReturnThrow.fir.kt   |  14 +
 .../ExhaustiveValOverConditionalInit.fir.kt   |  22 ++
 .../ExhaustiveVarOverConditionalInit.fir.kt   |  22 ++
 .../ExhaustiveWithNullabilityCheck.fir.kt     |  14 +
 ...xhaustiveWithNullabilityCheckBefore.fir.kt |  12 +
 ...haustiveWithNullabilityCheckBoolean.fir.kt |  13 +
 .../ExhaustiveWithNullabilityCheckElse.fir.kt |  14 +
 .../tests/when/NoElseExpectedUnit.fir.kt      |   7 +
 .../tests/when/NoElseNoExpectedType.fir.kt    |   6 +
 .../when/NoElseReturnedCoercionToUnit.fir.kt  |  11 +
 ...NoElseReturnedFromLambdaExpectedInt.fir.kt |  11 +
 .../tests/when/NoElseReturnedNonUnit.fir.kt   |   5 +
 .../tests/when/NoElseReturnedUnit.fir.kt      |   6 +
 .../tests/when/NoElseWhenStatement.fir.kt     |   6 +
 .../when/NonExhaustiveBooleanNullable.fir.kt  |   8 +
 .../when/NonExhaustivePlatformEnum.fir.kt     |  20 +
 .../tests/when/NonExhaustiveWarning.fir.kt    |  11 +
 .../when/NonExhaustiveWarningElse.fir.kt      |  12 +
 .../when/NonExhaustiveWarningFalse.fir.kt     |  13 +
 .../NonExhaustiveWarningForSealedClass.fir.kt |  16 +
 .../when/NonExhaustiveWarningNull.fir.kt      |  14 +
 .../NonExhaustiveWithNullabilityCheck.fir.kt  |  12 +
 .../tests/when/PropertyNotInitialized.fir.kt  |  16 +
 .../tests/when/RedundantElse.fir.kt           |  68 ++++
 .../tests/when/ReservedExhaustiveWhen.fir.kt  |  37 ++
 .../tests/when/TopLevelSealed.fir.kt          |  22 ++
 .../diagnostics/tests/when/When.fir.kt        |  46 +++
 .../tests/when/WhenTypeDisjunctions.fir.kt    |  21 +
 .../diagnostics/tests/when/kt10439.fir.kt     |  13 +
 .../diagnostics/tests/when/kt10809.fir.kt     |  52 +++
 .../diagnostics/tests/when/kt10811.fir.kt     |  24 ++
 .../diagnostics/tests/when/kt4434.fir.kt      |  27 ++
 .../diagnostics/tests/when/kt9929.fir.kt      |  10 +
 .../diagnostics/tests/when/kt9972.fir.kt      |  18 +
 .../when/whenAndLambdaWithExpectedType.fir.kt |  25 ++
 .../when/whenWithNothingAndLambdas.fir.kt     |  39 ++
 .../capturingInInitializer.fir.kt             |  37 ++
 .../invisibleOutsideOfWhen.fir.kt             |  14 +
 .../jumpoutInInitializer.fir.kt               |  43 ++
 .../nestedWhenWithSubject.fir.kt              |  41 ++
 .../noSubjectVariableName.fir.kt              |  10 +
 .../reassignmentToWhenSubjectVariable.fir.kt  |  10 +
 .../shadowingOtherVariable.fir.kt             |  27 ++
 ...rtCastOnValueBoundToSubjectVariable.fir.kt |  49 +++
 .../smartCastsOnSubjectVariable.fir.kt        |   8 +
 .../smartcastToEnum.fir.kt                    |  18 +
 .../smartcastToSealed.fir.kt                  |  20 +
 .../softModifierName.fir.kt                   |   7 +
 .../subjectVariableInIsPattern.fir.kt         |   8 +
 .../unsupportedFeature.fir.kt                 |  16 +
 ...edVariableDeclarationsInWhenSubject.fir.kt |  29 ++
 .../unusedWhenSubjectVariable.fir.kt          |   8 +
 .../testsWithStdLib/ArrayOfNothing.fir.kt     |  55 +++
 .../CallCompanionProtectedNonStatic.fir.kt    |  93 +++++
 .../CallToMainRedeclaredInMultiFile.fir.kt    |   8 +
 .../InaccessibleInternalClass.fir.kt          |  15 +
 .../PropertyDelegateWithPrivateSet.fir.kt     |  12 +
 .../RedeclarationMainInMultiFileClass.fir.kt  |  11 +
 .../RenameOnImportHidesDefaultImport.fir.kt   |   9 +
 .../testsWithStdLib/addAllProjection.fir.kt   |  15 +
 .../ClassObjectAnnotatedWithItsKClass.fir.kt  |  12 +
 .../annotations/JvmSyntheticOnDelegate.fir.kt |  10 +
 .../annotations/Synchronized.fir.kt           |  31 ++
 ...chronizedOnInterfaceCompanionMember.fir.kt |  23 ++
 .../annotations/TransientOnDelegate.fir.kt    |   5 +
 .../annotations/Volatile.fir.kt               |  13 +
 .../annotationsOnUseSiteTargets.fir.kt        |  13 +
 .../illegalPlatformName.fir.kt                |  12 +
 .../annotationApplicability/jvmName.fir.kt    |  95 +++++
 .../jvmNameOnMangledNames.fir.kt              |  13 +
 .../multifileClassPart.fir.kt                 |  19 +
 ...ultifileClassPartWithJavaAnnotation.fir.kt |  40 ++
 .../suppressOnFunctionReference.fir.kt        |   4 +
 .../array.fir.kt                              |  24 ++
 .../simple.fir.kt                             |  30 ++
 .../useOfNonConstVal.fir.kt                   |  16 +
 .../vararg.fir.kt                             |  27 ++
 .../annotationParameters/kt10136.fir.kt       |   8 +
 .../nonConstValAsArgument.fir.kt              |  34 ++
 .../orderWithValue.fir.kt                     |   9 +
 .../orderWithoutValue.fir.kt                  |   8 +
 .../annotationParameters/valueArray.fir.kt    |  23 ++
 .../valueArrayAndOtherDefault.fir.kt          |  27 ++
 .../valueArrayOnly.fir.kt                     |  15 +
 .../valueArrayWithDefault.fir.kt              |  15 +
 .../javaAnnotationWithVarargArgument.fir.kt   |  11 +
 .../kotlinAnnotationWithVarargArgument.fir.kt |   7 +
 ...notationsTargetingLateinitAccessors.fir.kt |  14 +
 ...tationsTargetingNonExistentAccessor.fir.kt | 114 ++++++
 .../defaultValueMustBeConstant.fir.kt         |  22 ++
 .../annotations/explicitMetadata.fir.kt       |   9 +
 .../annotationAsArgument.fir.kt               |  19 +
 .../arg.fir.kt                                |   7 +
 .../argAndOtherDefault.fir.kt                 |   9 +
 .../argArray.fir.kt                           |   7 +
 .../argWithDefault.fir.kt                     |   8 +
 .../argWithDefaultAndOther.fir.kt             |   9 +
 .../twoArgs.fir.kt                            |   8 +
 .../value.fir.kt                              |   8 +
 .../valueAndOtherDefault.fir.kt               |  12 +
 .../valueArray.fir.kt                         |   9 +
 .../valueWithDefault.fir.kt                   |   9 +
 .../valueWithDefaultAndOther.fir.kt           |  10 +
 .../annotations/jvmDefault/generic.fir.kt     |  60 +++
 .../jvmDefault/javaOverride.fir.kt            |  72 ++++
 .../jvmDefault/jvmDefaultInInheritance.fir.kt |  36 ++
 .../annotations/jvmDefault/jvmDefaults.fir.kt | 322 +++++++++++++++
 .../jvmDefault/jvmDefaultsWithJava.fir.kt     | 162 ++++++++
 .../jvmDefault/noJvmDefaultFlag.fir.kt        |  29 ++
 .../jvmDefault/notInterface.fir.kt            |  22 ++
 .../jvmDefault/propertyAccessor.fir.kt        |  14 +
 .../jvmDefault/simpleOverride.fir.kt          |  31 ++
 .../jvmDefault/simplePropertyOverride.fir.kt  |  32 ++
 .../annotations/jvmDefault/superCall.fir.kt   |  62 +++
 .../jvmDefault/superCallAmbiguity.fir.kt      |  32 ++
 .../jvmDefault/superCallAmbiguity2.fir.kt     |  32 ++
 .../jvmDefault/superCallAmbiguity3.fir.kt     |  31 ++
 .../annotations/jvmDefault/target6.fir.kt     |  29 ++
 .../annotations/jvmDefault/target8.fir.kt     |  30 ++
 .../clashWithCompanionObjectField.fir.kt      |   8 +
 .../jvmField/inMultiFileFacade.fir.kt         |  13 +
 .../jvmField/inSingleFileFacade.fir.kt        |  12 +
 .../annotations/jvmField/interface13.fir.kt   |  59 +++
 .../jvmField/jvmFieldApplicability.fir.kt     | 143 +++++++
 .../JvmOverloadWithNoDefaults.fir.kt          |   7 +
 .../jvmOverloadsOnAbstractMethods.fir.kt      |  11 +
 ...adsOnAnnotationClassConstructor_1_3.fir.kt |   4 +
 ...adsOnAnnotationClassConstructor_1_4.fir.kt |   4 +
 .../jvmOverloads/jvmOverloadsOnPrivate.fir.kt |  23 ++
 .../incorrectJvmPackageName.fir.kt            |  27 ++
 ...piVersionIsAtLeastHasConstArguments.fir.kt |  23 ++
 .../jvmStatic/constOrJvmFieldProperty.fir.kt  |  18 +
 .../jvmStatic/constructorProperty.fir.kt      |   4 +
 .../jvmStatic/constructorProperty_LL13.fir.kt |   4 +
 .../annotations/jvmStatic/constructors.fir.kt |   8 +
 .../jvmStatic/finalAndAbstract.fir.kt         |  33 ++
 .../annotations/jvmStatic/functions.fir.kt    |  53 +++
 .../jvmStatic/functions_LL13.fir.kt           |  53 +++
 .../jvmStatic/interfaceCompanion_LL12.fir.kt  |  54 +++
 .../interfaceCompanion_LL13_16.fir.kt         |  55 +++
 .../interfaceCompanion_LL13_18.fir.kt         |  56 +++
 .../annotations/jvmStatic/localFun.fir.kt     |   7 +
 .../jvmStatic/localFun_LL13.fir.kt            |   7 +
 .../annotations/jvmStatic/property.fir.kt     |  45 +++
 .../jvmStatic/property_LL13.fir.kt            |  45 +++
 .../kClassArrayInAnnotationsInVariance.fir.kt |  29 ++
 ...kClassArrayInAnnotationsOutVariance.fir.kt |  29 ++
 .../kClass/kClassInAnnotation.fir.kt          |  20 +
 .../kClassInAnnotationsInVariance.fir.kt      |  27 ++
 .../kClassInAnnotationsOutVariance.fir.kt     |  27 ++
 .../kClass/kClassInvariantTP.fir.kt           |  23 ++
 ...assOutArrayInAnnotationsOutVariance.fir.kt |   7 +
 .../kotlinAnnotation.fir.kt                   |   5 +
 .../tooManyArgs.fir.kt                        |  11 +
 .../typeMismatch.fir.kt                       |  13 +
 .../withValue.fir.kt                          |  17 +
 .../withoutValue.fir.kt                       |  17 +
 .../annotations/qualifiedCallValue.fir.kt     |  27 ++
 .../annotations/strictfpOnClass.fir.kt        |  17 +
 .../annotations/targetuse.fir.kt              |  21 +
 .../testsWithStdLib/assert/cast.fir.kt        |  21 +
 .../testsWithStdLib/assert/safeCall.fir.kt    |  38 ++
 .../builtins/arraysAreCloneable.fir.kt        |  25 ++
 .../testsWithStdLib/cast/AsInsideIn.fir.kt    |  21 +
 .../testsWithStdLib/cast/IsArray.fir.kt       |   5 +
 .../testsWithStdLib/cast/IsReified.fir.kt     |   1 +
 .../testsWithStdLib/commonCollections.fir.kt  |  30 ++
 .../breakContinuesInInlinedLambda.fir.kt      |  51 +++
 .../flowInlining/expressionBody.fir.kt        |  18 +
 .../implicitCastToAnyInReturnType.fir.kt      |  20 +
 .../inlinedLambdaAlwaysThrows.fir.kt          |  17 +
 .../irrelevantUnknownClosure.fir.kt           |  23 ++
 .../flowInlining/labeledReturns.fir.kt        |  86 ++++
 .../flowInlining/nestedTryCatchFinally.fir.kt |  98 +++++
 .../flowInlining/nestedTryCatchs.fir.kt       |  47 +++
 .../flowInlining/nonLocalReturn.fir.kt        |  18 +
 .../nonReturningInlinedLambda.fir.kt          |  34 ++
 .../safeCallAndInPlaceReturn.fir.kt           |  23 ++
 .../severalJumpOutsFromInlinedLambda.fir.kt   |  79 ++++
 .../flowInlining/throwIfNotCalled.fir.kt      |  48 +++
 .../controlflow/flowInlining/tryCatch.fir.kt  |  58 +++
 .../flowInlining/tryCatchFinally.fir.kt       |  34 ++
 .../flowInlining/typeMismatch.fir.kt          |  19 +
 .../flowInlining/unreachableCode.fir.kt       |  17 +
 .../valDefiniteReassignment.fir.kt            |  75 ++++
 .../varDefiniteInitialization.fir.kt          |  31 ++
 .../varIndefiniteIntialization.fir.kt         |  29 ++
 .../valDefiniteInitialization.fir.kt          |  92 +++++
 .../valDefiniteReassignment.fir.kt            |  28 ++
 .../valIndefiniteInitialization.fir.kt        |  68 ++++
 .../varDefiniteInitalization.fir.kt           |  42 ++
 .../varIndefiniteInitialization.fir.kt        |  51 +++
 .../exactlyOnce/withReceiver.fir.kt           |  28 ++
 .../unknown/unknownInvocations.fir.kt         |  18 +
 .../dsl/callUsualContractFunction.fir.kt      |  42 ++
 .../dsl/errors/booleanComparisons.fir.kt      |  23 ++
 .../errors/callInContractDescription.fir.kt   |  14 +
 .../dsl/errors/contractCallSites.fir.kt       |  86 ++++
 .../contracts/dsl/errors/emptyContract.fir.kt |   9 +
 .../illegalConstructionInContractBlock.fir.kt |  55 +++
 .../dsl/errors/illegalEqualsCondition.fir.kt  |  30 ++
 .../errors/nestedConditionalEffects.fir.kt    |  11 +
 .../errors/nonLambdaLiteralAsArgument.fir.kt  |  15 +
 .../dsl/errors/notFirstStatement.fir.kt       |  76 ++++
 .../dsl/errors/recursiveContract.fir.kt       |  25 ++
 ...rsiveContractCustomContractFunction.fir.kt |  39 ++
 .../dsl/errors/referenceToProperty.fir.kt     |  14 +
 .../dsl/errors/typeReferences.fir.kt          |  53 +++
 .../dsl/errors/unlabeledReceiver.fir.kt       |  12 +
 .../contracts/dsl/fqnContractFunction.fir.kt  |  20 +
 .../dsl/rewriteAtSliceFunctor.fir.kt          |  10 +
 .../contracts/dsl/useBeforeDeclaration.fir.kt |  20 +
 .../contracts/fromStdlib/check.fir.kt         |  33 ++
 .../fromStdlib/fromStandardKt.fir.kt          | 110 ++++++
 .../contracts/fromStdlib/isNullOrBlank.fir.kt |  20 +
 .../contracts/fromStdlib/isNullOrEmpty.fir.kt |  20 +
 .../contracts/fromStdlib/require.fir.kt       |  27 ++
 .../contracts/fromStdlib/synchronize.fir.kt   |  11 +
 .../smartcasts/callWithDefaultValue.fir.kt    |  17 +
 .../smartcasts/catchExceptionSpilling.fir.kt  |  21 +
 .../contracts/smartcasts/compositions.fir.kt  |  70 ++++
 .../contracts/smartcasts/deeplyNested.fir.kt  | 104 +++++
 .../smartcasts/extensionReceiver.fir.kt       |  38 ++
 .../smartcasts/extensionReceiver_after.fir.kt |  38 ++
 .../smartcasts/intersectingInfo.fir.kt        |  61 +++
 .../smartcasts/intersectionTypes.fir.kt       |  45 +++
 .../smartcasts/multieffect/implicitIff.fir.kt |  87 ++++
 .../multieffect/returnsAndCalls.fir.kt        |  68 ++++
 ...nullabilitySmartcastWhenNullability.fir.kt |  57 +++
 .../operatorsTests/andOperator.fir.kt         |  81 ++++
 .../andOperatorWithConstant.fir.kt            |  60 +++
 .../andOperatorWithUnknown.fir.kt             |  60 +++
 .../operatorsTests/equalsOperator.fir.kt      |  47 +++
 .../equalsWithNullableBoolean.fir.kt          |  69 ++++
 .../operatorsTests/isInstanceOperator.fir.kt  |  60 +++
 .../operatorsTests/orOperator.fir.kt          |  78 ++++
 .../orOperatorWithConstant.fir.kt             |  57 +++
 .../orOperatorWithUnknown.fir.kt              |  60 +++
 .../smartcasts/partiallyIncorrect.fir.kt      |  21 +
 .../contracts/smartcasts/receiver.fir.kt      |  36 ++
 .../smartcasts/safecallAndReturnsNull.fir.kt  |  17 +
 .../contracts/smartcasts/throwsEffect.fir.kt  |  66 ++++
 .../typeSmartcastWhenNullability.fir.kt       |  59 +++
 .../smartcasts/unreachableBranches.fir.kt     |  32 ++
 .../valueOfContractedFunctionIngored.fir.kt   |  11 +
 .../smartcasts/when/withSubject.fir.kt        |  36 ++
 .../when/withSubjectNullableBoolean.fir.kt    |  56 +++
 .../smartcasts/when/withoutSubject.fir.kt     |  31 ++
 .../deprecated/deprecationOnReadBytes.fir.kt  |   7 +
 .../noDeprecationOnReadBytes.fir.kt           |   9 +
 .../delegatedProperty.fir.kt                  |   7 +
 .../duplicateJvmSignature/jvmNames.fir.kt     |  22 ++
 .../jvmNamesDuplicate.fir.kt                  |  53 +++
 .../duplicateJvmSignature/jvmOverloads.fir.kt |   8 +
 .../jvmStaticInClassObject.fir.kt             |   9 +
 .../jvmStaticInObject.fir.kt                  |   8 +
 .../duplicateJvmSignature/statics/jjk.fir.kt  |  31 ++
 .../duplicateJvmSignature/statics/jk.fir.kt   |  21 +
 .../duplicateJvmSignature/statics/jkjk.fir.kt |  36 ++
 ...otlinMembersVsJavaNonVisibleStatics.fir.kt |  22 ++
 .../testsWithStdLib/elvisOnJavaList.fir.kt    |  19 +
 .../testsWithStdLib/elvisOnUnitInLet.fir.kt   |   9 +
 .../experimental/annotation.fir.kt            | 136 +++++++
 .../experimental/bodyUsages.fir.kt            |  30 ++
 .../experimental/bodyUsagesAndInline.fir.kt   |  83 ++++
 .../experimental/classMembers.fir.kt          |  88 +++++
 .../classMembersOverlyExperimental.fir.kt     |  36 ++
 .../experimental/constVal.fir.kt              |  43 ++
 .../experimental/deeplyNestedClass.fir.kt     |  57 +++
 .../experimental/errors.fir.kt                |  26 ++
 .../experimentalIsNotEnabled.fir.kt           |  23 ++
 .../experimentalOnWholeModule.fir.kt          |  23 ++
 .../experimentalUnsignedLiterals.fir.kt       |  33 ++
 .../experimental/fullFqNameUsage.fir.kt       |  12 +
 .../experimental/importStatement.fir.kt       |  27 ++
 ...ectTargetsForExperimentalAnnotation.fir.kt |  25 ++
 .../incorrectUseExperimental.fir.kt           |   9 +
 .../experimental/override.fir.kt              |  44 +++
 .../overrideDifferentExperimentalities.fir.kt |  35 ++
 .../experimental/topLevel.fir.kt              |  78 ++++
 .../experimental/typealias.fir.kt             |  13 +
 .../experimental/usageNotAsAnnotation.fir.kt  |  77 ++++
 .../experimental/useExperimentalOnFile.fir.kt |  37 ++
 ...talOnFileWithVeryExperimentalMarker.fir.kt |  30 ++
 .../useExperimentalOnWholeModule.fir.kt       |  22 ++
 .../useExperimentalTargets.fir.kt             |  57 +++
 ...eExperimentalWithSeveralAnnotations.fir.kt |  52 +++
 .../experimental/wasExperimental.fir.kt       |  59 +++
 ...uredRangeVariableAssignmentBefore13.fir.kt | 103 +++++
 ...forInFieldUpdatedInLoopBodyBefore13.fir.kt |  15 +
 ...DelegatedPropertyAssignmentBefore13.fir.kt |  16 +
 .../rangeVariableAssignment13.fir.kt          |  19 +
 .../rangeVariableAssignmentBefore13.fir.kt    |  39 ++
 .../pseudocodeMemoryOverhead.fir.kt           | 371 ++++++++++++++++++
 .../hugeUnresolvedKotlinxHtml.fir.kt          |  60 +++
 .../testsWithStdLib/ifElseJavaList.fir.kt     |  16 +
 .../testsWithStdLib/implicitCastToAny.fir.kt  |  34 ++
 .../exactAnnotation.fir.kt                    |  12 +
 ...xplicitTypeArgumentAsValidInputType.fir.kt |  12 +
 .../internalAnnotationsOnTypes.fir.kt         |  30 ++
 .../annotationsForResolve/kt26698.fir.kt      |  22 ++
 .../annotationsForResolve/kt29307.fir.kt      |  31 ++
 .../noInferAndLowPriority.fir.kt              |  16 +
 .../noInferAnnotation.fir.kt                  |  33 ++
 .../notNullAnnotation.fir.kt                  |  26 ++
 .../onlyInputTypes.fir.kt                     |  47 +++
 .../onlyInputTypesAndLowPriority.fir.kt       |  26 ++
 ...yInputTypesAndTopLevelCapturedTypes.fir.kt |  73 ++++
 ...putTypesAnnotationWithPlatformTypes.fir.kt |  19 +
 .../onlyInputTypesCaptured.fir.kt             | 113 ++++++
 .../onlyInputTypesWithVarargs.fir.kt          |  26 ++
 .../propagationOfNoInferAnnotation.fir.kt     |  25 ++
 ...resolveWithOnlyInputTypesAnnotation.fir.kt |  25 ++
 .../inference/arrayConstructor.fir.kt         |  14 +
 .../inference/integerLiterals.fir.kt          |  24 ++
 .../inference/intersectionInputType.fir.kt    |  12 +
 .../testsWithStdLib/inference/kt11266.fir.kt  |   4 +
 .../testsWithStdLib/inference/kt12008.fir.kt  |  12 +
 .../testsWithStdLib/inference/kt1558.fir.kt   |  26 ++
 .../testsWithStdLib/inference/kt27772.fir.kt  |   9 +
 .../testsWithStdLib/inference/kt30292.fir.kt  |   5 +
 .../testsWithStdLib/inference/kt32345.fir.kt  |  49 +++
 .../testsWithStdLib/inference/kt3458.fir.kt   |   9 +
 .../testsWithStdLib/inference/kt4975.fir.kt   |  10 +
 ...inlineOnlySuppressesNothingToInline.fir.kt |  31 ++
 .../inline/synchronizedOnInline.fir.kt        |  16 +
 .../diagnostics/testsWithStdLib/instar.fir.kt |  11 +
 .../java/concurrentHashMapContains.fir.kt     |  79 ++++
 .../concurrentHashMapContainsError.fir.kt     |  80 ++++
 .../testsWithStdLib/java/functionN.fir.kt     |  58 +++
 .../java/inheritedFunctionN.fir.kt            |  16 +
 .../patternCompileCallableReference.fir.kt    |   8 +
 .../javaClassOnCompanion.fir.kt               |  32 ++
 .../testsWithStdLib/javaForKClass.fir.kt      |  28 ++
 .../testsWithStdLib/kt7585/delegate.fir.kt    |  76 ++++
 .../diagnostics/testsWithStdLib/kt8050.fir.kt |  11 +
 .../diagnostics/testsWithStdLib/kt9078.fir.kt |  12 +
 .../diagnostics/testsWithStdLib/kt9985.fir.kt |   3 +
 .../lateinit/isInitialized.fir.kt             |  87 ++++
 .../multiplatform/jvmOverloads.fir.kt         |  11 +
 .../testsWithStdLib/native/abstract.fir.kt    |  11 +
 .../testsWithStdLib/native/body.fir.kt        |  25 ++
 .../testsWithStdLib/native/constructor.fir.kt |  10 +
 .../testsWithStdLib/native/inline.fir.kt      |  11 +
 .../testsWithStdLib/native/noBody.fir.kt      |  25 ++
 .../testsWithStdLib/native/nonFunction.fir.kt |   9 +
 .../testsWithStdLib/native/override.fir.kt    |   9 +
 .../testsWithStdLib/native/reified.fir.kt     |   4 +
 .../testsWithStdLib/native/trait.fir.kt       |  11 +
 .../testsWithStdLib/outstar.fir.kt            |  11 +
 .../overrideWithFunctionalType.fir.kt         |  17 +
 .../testsWithStdLib/pureReifiable.fir.kt      |  12 +
 .../pureReifiableArrayOperations.fir.kt       |  18 +
 .../arrayList.fir.kt                          |  23 ++
 .../arrayListNullable.fir.kt                  |  23 ++
 .../customClassMutableCollection.fir.kt       |  33 ++
 .../customClassMutableList.fir.kt             |  41 ++
 .../invalidFqName.fir.kt                      |  28 ++
 .../purelyImplementedCollection/maps.fir.kt   |  81 ++++
 .../mapsWithNullableKey.fir.kt                |  57 +++
 .../mapsWithNullableValues.fir.kt             |  56 +++
 .../purelyImplementedCollection/sets.fir.kt   |  49 +++
 .../wrongTypeParametersCount.fir.kt           |  40 ++
 .../typeOfWithNonReifiedParameter.fir.kt      |  35 ++
 .../testsWithStdLib/regression/ea63992.fir.kt |   7 +
 .../testsWithStdLib/regression/ea65206.fir.kt |   9 +
 .../ea66827_dataClassWrongToString.fir.kt     |   7 +
 .../ea70485_functionTypeInheritor.fir.kt      |  17 +
 .../regression/ea70880_illegalJvmName.fir.kt  |   8 +
 .../testsWithStdLib/regression/kt10001.fir.kt |   9 +
 .../testsWithStdLib/regression/kt2082.fir.kt  |  10 +
 .../testsWithStdLib/regression/kt26806.fir.kt |   9 +
 .../testsWithStdLib/regression/kt34391.fir.kt |  19 +
 .../testsWithStdLib/regression/kt9345.fir.kt  |   3 +
 .../kt9820_javaFunctionTypeInheritor.fir.kt   |  16 +
 .../reified/arrayConstruction.fir.kt          |  18 +
 .../reified/arrayOfNullsReified.fir.kt        |  14 +
 .../testsWithStdLib/reified/kt11881.fir.kt    |   9 +
 .../reified/nonCallableReiefied.fir.kt        |  11 +
 .../reified/reifiedNothingSubstitution.fir.kt |  17 +
 .../resolve/hidesMembers.fir.kt               |  52 +++
 .../resolve/hidesMembers2.fir.kt              |  42 ++
 .../resolve/javaPackageMembers.fir.kt         |   9 +
 .../resolve/javaStaticMembers.fir.kt          |  12 +
 .../testsWithStdLib/resolve/kt10103.fir.kt    |   1 +
 .../testsWithStdLib/resolve/kt10732a.fir.kt   |  10 +
 .../testsWithStdLib/resolve/kt4711.fir.kt     |  21 +
 .../resolve/samAgainstFunctionalType.fir.kt   |  30 ++
 .../resolve/samConstructorVsFun.fir.kt        |  30 ++
 .../resolve/samOverloadsWithGenerics.fir.kt   |  25 ++
 ...loadsWithGenericsWithoutRefinedSams.fir.kt |  26 ++
 .../resolve/samOverloadsWithKtFunction.fir.kt |  20 +
 ...adsWithKtFunctionWithoutRefinedSams.fir.kt |  22 ++
 .../shadowingInDestructuring.fir.kt           |  10 +
 .../smartcasts/forEachSafe.fir.kt             |  12 +
 .../smartcasts/forEachUnsafe.fir.kt           |  14 +
 .../testsWithStdLib/smartcasts/kt10463.fir.kt |   6 +
 .../smartcasts/lazyDeclaresAndModifies.fir.kt |  11 +
 .../letAlwaysChangesToNotNull.fir.kt          |   7 +
 .../smartcasts/letChangesToNotNull.fir.kt     |   7 +
 .../smartcasts/letChangesToNull.fir.kt        |   9 +
 .../smartcasts/letChangesToNullComplex.fir.kt |  11 +
 .../smartcasts/letMergeNotNull.fir.kt         |   9 +
 .../smartcasts/letStable.fir.kt               |  10 +
 .../smartcasts/letUsesOwnReceiver.fir.kt      |   7 +
 .../smartcasts/listOfGeneric.fir.kt           |   8 +
 .../smartcasts/withChangesToNull.fir.kt       |  10 +
 .../noDefaultImportOfKotlinComparisons.fir.kt |   3 +
 .../testsWithStdLib/streams.fir.kt            |   9 +
 .../targetedBuiltIns/blackListed.fir.kt       |  22 ++
 .../unsupportedFeature.fir.kt                 |  66 ++++
 ...iableDeclarationWithDisabledFeature.fir.kt |  19 +
 ...riableDeclarationWithEnabledFeature.fir.kt |  20 +
 .../trailingComma/noDisambiguation.fir.kt     |  10 +
 .../typeArgumentsWithDisabledFeature.fir.kt   |  28 ++
 .../typeArgumentsWithEnabledFeature.fir.kt    |  28 ++
 .../typeParametersWithDisabledFeature.fir.kt  |  48 +++
 .../typeParametersWithEnabledFeature.fir.kt   |  51 +++
 .../valueArgumentsWithDisabledFeature.fir.kt  |  73 ++++
 .../valueArgumentsWithEnabledFeature.fir.kt   |  69 ++++
 .../valueParametersWithDisabledFeature.fir.kt | 120 ++++++
 .../valueParametersWithEnabledFeature.fir.kt  | 104 +++++
 .../whenEntryWithDisabledFeature.fir.kt       |  49 +++
 .../whenEntryWithEnabledFeature.fir.kt        |  50 +++
 .../testsWithStdLib/tryCatch/assignTry.fir.kt | 111 ++++++
 .../tryCatch/boundedSmartcasts.fir.kt         | 101 +++++
 .../tryCatch/catchRedeclaration.fir.kt        |  54 +++
 .../tryCatch/correctSmartcasts.fir.kt         |  88 +++++
 .../tryCatch/correctSmartcasts_after.fir.kt   |  89 +++++
 .../tryCatch/falseNegativeSmartcasts.fir.kt   |  19 +
 .../falseNegativeSmartcasts_after.fir.kt      |  20 +
 .../tryCatch/falsePositiveSmartcasts.fir.kt   | 106 +++++
 .../falsePositiveSmartcasts_after.fir.kt      | 108 +++++
 .../tryCatch/tryExpression.fir.kt             |  35 ++
 .../typealias/exceptionTypeAliases.fir.kt     |   3 +
 ...peAliasesInvisibleWithApiVersion1_0.fir.kt |   5 +
 ...nTypeAliasesInvisibleWithoutFeature.fir.kt |   4 +
 .../typealias/hashMapTypeAlias.fir.kt         |  20 +
 .../typeAliasSamAdapterConstructors.fir.kt    |   8 +
 .../typeAliasSamAdapterConstructors2.fir.kt   |  27 ++
 .../testsWithStdLib/varargs/kt3213.fir.kt     |   7 +
 .../testsWithStdLib/varargs/kt4172j.fir.kt    |   9 +
 .../testsWithStdLib/varargs/kt5534.fir.kt     |   6 +
 .../testsWithStdLib/when/kt10192.fir.kt       |  20 +
 .../testsWithStdLib/when/kt10807.fir.kt       |  17 +
 .../when/noTypeArgumentsInConstructor.fir.kt  |  43 ++
 4578 files changed, 104067 insertions(+), 1 deletion(-)
 create mode 100644 compiler/testData/diagnostics/tests/Abstract.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AbstractAccessor.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AbstractInAbstractClass.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AbstractInClass.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AbstractInTrait.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AnonymousInitializerVarAndConstructor.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AnonymousInitializers.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AssignToArrayElement.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/AutoCreatedIt.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/BacktickNames.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/Basic.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/BinaryCallsOnNullableValues.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/Bounds.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/BreakContinue.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/BreakContinueInWhen_after.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/BreakContinueInWhen_before.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/Builders.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/Casts.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/CharacterLiterals.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/CompareToWithErrorType.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/Constants.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/Constructors.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/ConstructorsOfPrimitives.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/CovariantOverrideType.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/DefaultValueForParameterInFunctionType.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/DefaultValuesCheckWithoutBody.fir.kt
 create mode 100644 compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt
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 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/kt10103.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/kt10732a.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/kt4711.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/samAgainstFunctionalType.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/samConstructorVsFun.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenerics.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenericsWithoutRefinedSams.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunction.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunctionWithoutRefinedSams.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/shadowingInDestructuring.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachSafe.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachUnsafe.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/kt10463.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/lazyDeclaresAndModifies.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/letAlwaysChangesToNotNull.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNotNull.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNull.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNullComplex.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/letMergeNotNull.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/letStable.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/letUsesOwnReceiver.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/listOfGeneric.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/smartcasts/withChangesToNull.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/sourceCompatibility/noDefaultImportOfKotlinComparisons.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/streams.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/blackListed.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/unsupportedFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt
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 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/noDisambiguation.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithEnabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithEnabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithEnabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithEnabledFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt
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 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/tryCatch/assignTry.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/tryCatch/boundedSmartcasts.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/tryCatch/catchRedeclaration.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/tryCatch/correctSmartcasts.fir.kt
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 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts_after.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/tryCatch/tryExpression.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliases.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithApiVersion1_0.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithoutFeature.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/typealias/hashMapTypeAlias.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors2.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/varargs/kt3213.fir.kt
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 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/varargs/kt5534.fir.kt
 create mode 100644 compiler/testData/diagnostics/testsWithStdLib/when/kt10192.fir.kt
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diff --git a/compiler/testData/diagnostics/tests/Abstract.fir.kt b/compiler/testData/diagnostics/tests/Abstract.fir.kt
new file mode 100644
index 00000000000..fa1c36427a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Abstract.fir.kt
@@ -0,0 +1,61 @@
+// FILE: b.kt
+package MyPackage
+    //properties
+    val a: Int
+    val a1: Int = 1
+    abstract val a2: Int
+    abstract val a3: Int = 1
+
+    var b: Int                private set
+    var b1: Int = 0;                         private set
+    abstract var b2: Int      private set
+    abstract var b3: Int = 0; private set
+
+    var c: Int                set(v: Int) { field = v }
+    var c1: Int = 0;                         set(v: Int) { field = v }
+    abstract var c2: Int      set(v: Int) { field = v }
+    abstract var c3: Int = 0; set(v: Int) { field = v }
+
+    val e: Int                               get() = a
+    val e1: Int = 0;          get() = a
+    abstract val e2: Int      get() = a
+    abstract val e3: Int = 0; get() = a
+
+    //methods
+    fun f()
+    fun g() {}
+    abstract fun h()
+    abstract fun j() {}
+
+    //property accessors
+    var i: Int                       abstract get  abstract set
+    var i1: Int = 0;  abstract get  abstract set
+
+    var j: Int                       get() = i;    abstract set
+    var j1: Int = 0;  get() = i;    abstract set
+
+    var k: Int        abstract set
+    var k1: Int = 0;                 abstract set
+
+    var l: Int                       abstract get  abstract set
+    var l1: Int = 0;  abstract get  abstract set
+
+    var n: Int                       abstract get abstract set(v: Int) {}
+
+// FILE: c.kt
+//creating an instance
+abstract class B1(
+    val i: Int,
+    val s: String
+) {
+}
+
+class B2() : B1(1, "r") {}
+
+abstract class B3(i: Int) {
+}
+
+fun foo(c: B3) {
+    val a = B3(1)
+    val b = B1(2, "s")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/AbstractAccessor.fir.kt b/compiler/testData/diagnostics/tests/AbstractAccessor.fir.kt
new file mode 100644
index 00000000000..3bfbc333f51
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AbstractAccessor.fir.kt
@@ -0,0 +1,21 @@
+abstract class My {
+    abstract var x: Int
+        public get
+        private set
+
+    abstract val y: Int
+        protected get
+
+    abstract protected var z: Int
+        internal get
+        private set
+
+    abstract internal val w: Int
+        protected get
+
+    abstract var u: Int
+        protected set
+
+    open var t: Int = 0
+        private set
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/AbstractInAbstractClass.fir.kt b/compiler/testData/diagnostics/tests/AbstractInAbstractClass.fir.kt
new file mode 100644
index 00000000000..5fa3158c3ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AbstractInAbstractClass.fir.kt
@@ -0,0 +1,45 @@
+package abstract
+
+abstract class MyAbstractClass() {
+    //properties
+    val a: Int
+    val a1: Int = 1
+    abstract val a2: Int
+    abstract val a3: Int = 1
+
+    var b: Int                private set
+    var b1: Int = 0;                         private set
+    abstract var b2: Int      private set
+    abstract var b3: Int = 0; private set
+
+    var c: Int                set(v: Int) { field = v }
+    var c1: Int = 0;                         set(v: Int) { field = v }
+    abstract var c2: Int                     set(v: Int) { field = v }
+    abstract var c3: Int = 0; set(v: Int) { field = v }
+
+    val e: Int                               get() = a
+    val e1: Int = 0;          get() = a
+    abstract val e2: Int                     get() = a
+    abstract val e3: Int = 0; get() = a
+
+    //methods
+    fun f()
+    fun g() {}
+    abstract fun h()
+    abstract fun j() {}
+
+    //property accessors
+    var i: Int                       abstract get  abstract set
+    var i1: Int = 0;  abstract get  abstract set
+
+    var j: Int                       get() = i;    abstract set
+    var j1: Int                      get() = i;    abstract set
+
+    var k: Int        abstract set
+    var k1: Int = 0;                 abstract set
+
+    var l: Int                       abstract get  abstract set
+    var l1: Int = 0;  abstract get  abstract set
+
+    var n: Int                       abstract get abstract set(v: Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/AbstractInClass.fir.kt b/compiler/testData/diagnostics/tests/AbstractInClass.fir.kt
new file mode 100644
index 00000000000..ca2612d35bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AbstractInClass.fir.kt
@@ -0,0 +1,45 @@
+package abstract
+
+class MyClass() {
+    //properties
+    val a: Int
+    val a1: Int = 1
+    abstract val a2: Int
+    abstract val a3: Int = 1
+
+    var b: Int                private set
+    var b1: Int = 0;                         private set
+    abstract var b2: Int      private set
+    abstract var b3: Int = 0; private set
+
+    var c: Int                set(v: Int) { field = v }
+    var c1: Int = 0;                         set(v: Int) { field = v }
+    abstract var c2: Int      set(v: Int) { field = v }
+    abstract var c3: Int = 0; set(v: Int) { field = v }
+
+    val e: Int                               get() = a
+    val e1: Int = 0;          get() = a
+    abstract val e2: Int      get() = a
+    abstract val e3: Int = 0; get() = a
+
+    //methods
+    fun f()
+    fun g() {}
+    abstract fun h()
+    abstract fun j() {}
+
+    //property accessors
+    var i: Int                       abstract get  abstract set
+    var i1: Int = 0;  abstract get  abstract set
+
+    var j: Int                       get() = i;    abstract set
+    var j1: Int = 0;  get() = i;    abstract set
+
+    var k: Int        abstract set
+    var k1: Int = 0;                 abstract set
+
+    var l: Int                       abstract get  abstract set
+    var l1: Int = 0;  abstract get  abstract set
+
+    var n: Int                       abstract get abstract set(v: Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/AbstractInTrait.fir.kt b/compiler/testData/diagnostics/tests/AbstractInTrait.fir.kt
new file mode 100644
index 00000000000..2560ef10b9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AbstractInTrait.fir.kt
@@ -0,0 +1,45 @@
+package abstract
+
+interface MyTrait {
+    //properties
+    val a: Int
+    val a1: Int = 1
+    abstract val a2: Int
+    abstract val a3: Int = 1
+
+    var b: Int                                                                                              private set
+    var b1: Int = 0;                                                private set
+    abstract var b2: Int                                               private set
+    abstract var b3: Int = 0; private set
+
+    var c: Int                                   set(v: Int) { field = v }
+    var c1: Int = 0;              set(v: Int) { field = v }
+    abstract var c2: Int                     set(v: Int) { field = v }
+    abstract var c3: Int = 0; set(v: Int) { field = v }
+
+    val e: Int                                                  get() = a
+    val e1: Int = 0;                             get() = a
+    abstract val e2: Int                     get() = a
+    abstract val e3: Int = 0; get() = a
+
+    //methods
+    fun f()
+    fun g() {}
+    abstract fun h()
+    abstract fun j() {}
+
+    //property accessors
+    var i: Int                       abstract get  abstract set
+    var i1: Int = 0;  abstract get  abstract set
+
+    var j: Int                       get() = i;    abstract set
+    var j1: Int = 0;  get() = i;    abstract set
+
+    var k: Int                       abstract set
+    var k1: Int = 0;  abstract set
+
+    var l: Int                       abstract get  abstract set
+    var l1: Int = 0;  abstract get  abstract set
+
+    var n: Int                       abstract get abstract set(v: Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/AnonymousInitializerVarAndConstructor.fir.kt b/compiler/testData/diagnostics/tests/AnonymousInitializerVarAndConstructor.fir.kt
new file mode 100644
index 00000000000..65e6d55d878
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AnonymousInitializerVarAndConstructor.fir.kt
@@ -0,0 +1,10 @@
+// http://youtrack.jetbrains.net/issue/KT-419
+
+class A(w: Int) {
+    var c = w
+
+    init {
+        c = 81
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/AnonymousInitializers.fir.kt b/compiler/testData/diagnostics/tests/AnonymousInitializers.fir.kt
new file mode 100644
index 00000000000..f066a44ab9b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AnonymousInitializers.fir.kt
@@ -0,0 +1,26 @@
+interface NoC {
+  init {
+
+  }
+
+  val a : Int get() = 1
+
+  init {
+
+  }
+}
+
+class WithC() {
+  val x : Int = 1
+  init {
+    val b = x
+
+  }
+
+  val a : Int get() = 1
+
+  init {
+    val z = b
+    val zz = x
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/AssignToArrayElement.fir.kt b/compiler/testData/diagnostics/tests/AssignToArrayElement.fir.kt
new file mode 100644
index 00000000000..43f8284a476
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AssignToArrayElement.fir.kt
@@ -0,0 +1,10 @@
+fun getArray(): Array<Int> = throw Exception()
+fun getList(): MutableList<Int> = throw Exception()
+fun fn() {
+    getArray()[1] = 2
+    getList()[1] = 2
+    getArray()[1]++
+    getList()[1]++
+    getArray()[1] += 2
+    getList()[1] += 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/AutoCreatedIt.fir.kt b/compiler/testData/diagnostics/tests/AutoCreatedIt.fir.kt
new file mode 100644
index 00000000000..52f3a1f0369
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/AutoCreatedIt.fir.kt
@@ -0,0 +1,33 @@
+// !WITH_NEW_INFERENCE
+fun text() {
+    "direct:a" to "mock:a"
+    "direct:a" on {it.body == "<hello/>"} to "mock:a"
+    "direct:a" on {it -> it.body == "<hello/>"} to "mock:a"
+    bar {1}
+    bar {<!UNRESOLVED_REFERENCE!>it<!> + 1}
+    bar {it, it1 -> it}
+
+    bar1 {1}
+    bar1 {it + 1}
+
+    bar2 {}
+    bar2 {1}
+    bar2 {<!UNRESOLVED_REFERENCE!>it<!>}
+    <!INAPPLICABLE_CANDIDATE!>bar2<!> {it -> it}
+}
+
+fun bar(f :  (Int, Int) -> Int) {}
+fun bar1(f :  (Int) -> Int) {}
+fun bar2(f :  () -> Int) {}
+
+infix fun String.to(dest : String) {
+
+}
+
+infix fun String.on(predicate :  (s : URI) -> Boolean) : URI {
+    return URI(this)
+}
+
+class URI(val body : Any) {
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun to(dest : String) {}<!>
+}
diff --git a/compiler/testData/diagnostics/tests/BacktickNames.fir.kt b/compiler/testData/diagnostics/tests/BacktickNames.fir.kt
new file mode 100644
index 00000000000..a1f1b49f01c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/BacktickNames.fir.kt
@@ -0,0 +1,94 @@
+//  !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+// TODO Uncomment all the examples when there will be no problems with light classes
+//package `foo.bar`
+
+// TODO: Uncomment after fixing KT-9416
+//import kotlin.Deprecated as `deprecate\entity`
+
+//@`deprecate\entity`("") data class Pair(val x: Int, val y: Int)
+
+// Names should not contains characters: '.', ';', '[', ']', '/', '<', '>', ':', '\\'
+//class `class.name`
+class `class;name`
+class `class[name`
+class `class]name`
+//class `class/name`
+class `class<name`
+class `class>name`
+class `class:name`
+class `class\name`
+
+class ` ` {}
+class `  `
+
+//val `val.X` = 10
+val `val;X` = 10
+val `val[X` = 10
+val `val]X` = 10
+//val `val/X` = 10
+val `val<X` = 10
+val `val>X` = 10
+val `val:X` = 10
+val `val\X` = 10
+
+val `;` = 1
+val `[` = 2
+val `]` = 3
+val `<` = 4
+
+val `>` = 5
+val `:` = 6
+val `\` = 7
+val `<>` = 8
+
+val `[]` = 9
+val `[;]` = 10
+
+// TODO Uncomment when there will be no problems with light classes (Error: Invalid formal type parameter (must be a valid Java identifier))
+//class AWithTypeParameter<`T:K`> {}
+//fun <`T/K`> genericFun(x: `T/K`) {}
+
+class B(val `a:b`: Int, val `c:d`: Int)
+
+val ff: (`x:X`: Int) -> Unit = {}
+val fg: ((`x:X`: Int) -> Unit) -> Unit = {}
+val fh: ((Int) -> ((`x:X`: Int) -> Unit) -> Unit) = {{}}
+
+fun f(x: Int, g: (Int) -> Unit) = g(x)
+
+data class Data(val x: Int,  val y: Int)
+
+class A() {
+    init {
+        val `a:b` = 10
+    }
+
+    fun g(`x:y`: Int) {
+        val `s:` = 30
+    }
+}
+
+fun `foo:bar`(`\arg`: Int): Int {
+    val (`a:b`, c) = Data(10, 20)
+    val `a\b` = 10
+
+    fun localFun() {}
+
+    for (`x/y` in 0..10) {
+    }
+
+    f(10) {
+        `x:z`: Int -> localFun()
+    }
+
+    f(20, fun(`x:z`: Int): Unit {})
+
+    try {
+        val `a:` = 10
+    }
+    catch (`e:a`: Exception) {
+        val `b:` = 20
+    }
+
+    return `\arg`
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Basic.fir.kt b/compiler/testData/diagnostics/tests/Basic.fir.kt
new file mode 100644
index 00000000000..6da1912608e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Basic.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+fun foo(u : Unit) : Int = 1
+
+fun test() : Int {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1)
+    val a : () -> Unit = {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(1)
+    }
+    return 1 - "1"
+}
+
+class A() {
+    val x : Int = <!INAPPLICABLE_CANDIDATE!>foo1<!>(<!UNRESOLVED_REFERENCE!>xx<!>)
+}
+
+fun foo1() {}
diff --git a/compiler/testData/diagnostics/tests/BinaryCallsOnNullableValues.fir.kt b/compiler/testData/diagnostics/tests/BinaryCallsOnNullableValues.fir.kt
new file mode 100644
index 00000000000..2d3b17bca8e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/BinaryCallsOnNullableValues.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+class A() {
+    override fun equals(other : Any?) : Boolean = false
+}
+
+fun f(): Unit {
+    var x: Int? = 1
+    x = null
+    x + 1
+    x plus 1
+    x < 1
+    x += 1
+
+    x == 1
+    x != 1
+
+    A() == 1
+
+    x === "1"
+    x !== "1"
+
+    x === 1
+    x !== 1
+
+    x<!UNRESOLVED_REFERENCE!>..<!>2
+    x in 1..2
+
+    val y : Boolean? = true
+    false || y
+    y && true
+    y && 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Bounds.fir.kt b/compiler/testData/diagnostics/tests/Bounds.fir.kt
new file mode 100644
index 00000000000..7f4547bc671
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Bounds.fir.kt
@@ -0,0 +1,43 @@
+// !WITH_NEW_INFERENCE
+// FILE: a.kt
+package boundsWithSubstitutors
+    open class A<T>
+    class B<X : A<X>>()
+
+    class C : A<C>()
+
+    val a = B<C>()
+    val a1 = B<Int>()
+
+    class X<A, B : A>()
+
+    val b = X<Any, X<A<C>, C>>()
+    val b0 = X<Any, Any?>()
+    val b1 = X<Any, X<A<C>, String>>()
+
+// FILE: b.kt
+  open class A {}
+  open class B<T : A>()
+
+  class Pair<A, B>
+
+  abstract class C<T : B<Int>, X :  (B<Char>) -> Pair<B<Any>, B<A>>>() : B<Any>() { // 2 errors
+    val a = B<Char>() // error
+
+    abstract val x :  (B<Char>) -> B<Any>
+  }
+
+
+fun test() {
+    foo<Int?>()
+    foo<Int>()
+    bar<Int?>()
+    bar<Int>()
+    bar<Double?>()
+    bar<Double>()
+    1.<!INAPPLICABLE_CANDIDATE!>buzz<!><Double>()
+}
+
+fun <T : Any> foo() {}
+fun <T : Int?> bar() {}
+fun <T : Int> Int.buzz() : Unit {}
diff --git a/compiler/testData/diagnostics/tests/BreakContinue.fir.kt b/compiler/testData/diagnostics/tests/BreakContinue.fir.kt
new file mode 100644
index 00000000000..9ed9dad5de2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/BreakContinue.fir.kt
@@ -0,0 +1,96 @@
+class C {
+
+    fun f (a : Boolean, b : Boolean) {
+        b@ while (true)
+          a@ {
+            break@f
+            break
+            break@b
+            break@a
+          }
+
+        continue
+
+        b@ while (true)
+          a@ {
+            continue@f
+            continue
+            continue@b
+            continue@a
+          }
+
+        break
+
+        continue@f
+        break@f
+    }
+
+    fun containsBreak(a: String?, b: String?) {
+        while (a == null) {
+            break;
+        }
+        a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("2")
+    }
+
+    fun notContainsBreak(a: String?, b: String?) {
+        while (a == null) {
+            while (b == null) {
+                break;
+            }
+        }
+        a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("2")
+    }
+
+    fun containsBreakWithLabel(a: String?) {
+        loop@ while(a == null) {
+            break@loop
+        }
+        a?.compareTo("2")
+    }
+
+    fun containsIllegalBreak(a: String?) {
+        loop@ while(a == null) {
+            break@label
+        }
+        a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("2")
+    }
+
+    fun containsBreakToOuterLoop(a: String?, b: String?) {
+        loop@ while(b == null) {
+            while(a == null) {
+                break@loop
+            }
+            a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("2")
+        }
+    }
+
+    fun containsBreakInsideLoopWithLabel(a: String?, array: Array<Int>) {
+        l@ while(a == null) {
+            for (el in array) {
+                break@l
+            }
+        }
+        a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("2")
+    }
+
+    fun unresolvedBreak(a: String?, array: Array<Int>) {
+        while(a == null) {
+            l@ for (el in array) {
+                break
+            }
+            if (true) break else break@l
+        }
+        a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("2")
+    }
+
+    fun twoLabelsOnLoop() {
+        label1@ label2@ for (i in 1..100) {
+            if (i > 0) {
+                break@label1
+            }
+            else {
+                break@label2
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/BreakContinueInWhen_after.fir.kt b/compiler/testData/diagnostics/tests/BreakContinueInWhen_after.fir.kt
new file mode 100644
index 00000000000..0d72e61d39f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/BreakContinueInWhen_after.fir.kt
@@ -0,0 +1,92 @@
+// !LANGUAGE: +AllowBreakAndContinueInsideWhen
+
+fun breakContinueInWhen(i: Int) {
+    for (y in 0..10) {
+        when(i) {
+            0 -> continue
+            1 -> break
+            2 -> {
+                for(z in 0..10) {
+                    break
+                }
+                for(w in 0..10) {
+                    continue
+                }
+            }
+        }
+    }
+}
+
+
+fun breakContinueInWhenWithWhile(i: Int, j: Int) {
+    while (i > 0) {
+        when (i) {
+            0 -> continue
+            1 -> break
+            2 -> {
+                while (j > 0) {
+                    break
+                }
+            }
+        }
+    }
+}
+
+fun breakContinueInWhenWithDoWhile(i: Int, j: Int) {
+    do {
+        when (i) {
+            0 -> continue
+            1 -> break
+            2 -> {
+                do {
+                    if (j == 5) break
+                    if (j == 10) continue
+                } while (j > 0)
+            }
+        }
+    } while (i > 0)
+}
+
+fun labeledBreakContinue(i: Int) {
+    outer@ for (y in 0..10) {
+        when (i) {
+            0 -> continue@outer
+            1 -> break@outer
+        }
+    }
+}
+
+fun testBreakContinueInWhenInWhileCondition() {
+    var i = 0
+    while (
+        when (i) {
+            1 -> break
+            2 -> continue
+            else -> true
+        }
+    ) {
+        ++i
+    }
+}
+
+fun testBreakContinueInWhenInDoWhileCondition() {
+    var i = 0
+    do {
+        ++i
+    } while (
+        when (i) {
+            1 -> break
+            2 -> continue
+            else -> true
+        }
+    )
+}
+
+fun testBreakContinueInWhenInForIteratorExpression(xs: List<Any>, i: Int) {
+    for (x in when (i) {
+        1 -> break
+        2 -> continue
+        else -> xs
+    }) {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/BreakContinueInWhen_before.fir.kt b/compiler/testData/diagnostics/tests/BreakContinueInWhen_before.fir.kt
new file mode 100644
index 00000000000..8d32c2adfce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/BreakContinueInWhen_before.fir.kt
@@ -0,0 +1,57 @@
+// !LANGUAGE: -AllowBreakAndContinueInsideWhen
+
+fun breakContinueInWhen(i: Int) {
+    for (y in 0..10) {
+        when(i) {
+            0 -> continue
+            1 -> break
+            2 -> {
+                for(z in 0..10) {
+                    break
+                }
+                for(w in 0..10) {
+                    continue
+                }
+            }
+        }
+    }
+}
+
+
+fun breakContinueInWhenWithWhile(i: Int, j: Int) {
+    while (i > 0) {
+        when (i) {
+            0 -> continue
+            1 -> break
+            2 -> {
+                while (j > 0) {
+                    break
+                }
+            }
+        }
+    }
+}
+
+fun breakContinueInWhenWithDoWhile(i: Int, j: Int) {
+    do {
+        when (i) {
+            0 -> continue
+            1 -> break
+            2 -> {
+                do {
+                    if (j == 5) break
+                    if (j == 10) continue
+                } while (j > 0)
+            }
+        }
+    } while (i > 0)
+}
+
+fun labeledBreakContinue(i: Int) {
+    outer@ for (y in 0..10) {
+        when (i) {
+            0 -> continue@outer
+            1 -> break@outer
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/Builders.fir.kt b/compiler/testData/diagnostics/tests/Builders.fir.kt
new file mode 100644
index 00000000000..dd611744660
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Builders.fir.kt
@@ -0,0 +1,159 @@
+// FILE: a.kt
+
+/**
+ * This is an example of a Type-Safe Groovy-style Builder
+ *
+ * Builders are good for declaratively describing data in your code.
+ * In this example we show how to describe an HTML page in Kotlin.
+ *
+ * See this page for details:
+ * http://confluence.jetbrains.net/display/Kotlin/Type-safe+Groovy-style+builders
+ */
+package html
+
+import java.util.*
+
+fun main(args : Array<String>) {
+  val result =
+    html {
+      head {
+        title {+"XML encoding with Kotlin"}
+      }
+      body {
+        h1 {+"XML encoding with Kotlin"}
+        p {+"this format can be used as an alternative markup to XML"}
+
+        // an element with attributes and text content
+        a(href = "https://jetbrains.com/kotlin") {+"Kotlin"}
+
+        // mixed content
+        p {
+          +"This is some"
+          b {+"mixed"}
+          +"text. For more see the"
+          a(href = "https://jetbrains.com/kotlin") {+"Kotlin"}
+          +"project"
+        }
+        p {+"some text"}
+
+        // content generated from command-line arguments
+        p {
+          +"Command line arguments were:"
+          ul {
+            for (arg in args)
+              li {+arg}
+          }
+        }
+      }
+    }
+  println(result)
+}
+
+abstract class Element {
+  abstract fun render(builder : StringBuilder, indent : String)
+
+  override fun toString() : String {
+    val builder = StringBuilder()
+    render(builder, "")
+    return builder.toString()
+  }
+}
+
+class TextElement(val text : String) : Element() {
+  override fun render(builder : StringBuilder, indent : String) {
+    builder.append("$indent$text\n")
+  }
+}
+
+abstract class Tag(val name : String) : Element() {
+  val children = ArrayList<Element>()
+  val attributes = HashMap<String, String>()
+
+  protected fun <T : Element> initTag(tag : T, init : T.() -> Unit) : T {
+    tag.<!UNRESOLVED_REFERENCE!>init<!>()
+    children.add(tag)
+    return tag
+  }
+
+  override fun render(builder : StringBuilder, indent : String) {
+    builder.append("$indent<$name${renderAttributes()}>\n")
+    for (c in children) {
+      c.render(builder, indent + "  ")
+    }
+    builder.append("$indent</$name>\n")
+  }
+
+  private fun renderAttributes() : String? {
+    val builder = StringBuilder()
+    for (a in attributes.keys) {
+      builder.append(" $a=\"${attributes[a]}\"")
+    }
+    return builder.toString()
+  }
+}
+
+abstract class TagWithText(name : String) : Tag(name) {
+  operator fun String.unaryPlus() {
+    children.add(TextElement(this))
+  }
+}
+
+class HTML() : TagWithText("html") {
+  fun head(init : Head.() -> Unit) = initTag(Head(), init)
+
+  fun body(init : Body.() -> Unit) = initTag(Body(), init)
+}
+
+class Head() : TagWithText("head") {
+  fun title(init : Title.() -> Unit) = initTag(Title(), init)
+}
+
+class Title() : TagWithText("title")
+
+abstract class BodyTag(name : String) : TagWithText(name) {
+  fun b(init : B.() -> Unit) = initTag(B(), init)
+  fun p(init : P.() -> Unit) = initTag(P(), init)
+  fun h1(init : H1.() -> Unit) = initTag(H1(), init)
+  fun ul(init : UL.() -> Unit) = initTag(UL(), init)
+  fun a(href : String, init : A.() -> Unit) {
+    val a = initTag(A(), init)
+    a.href = href
+  }
+}
+
+class Body() : BodyTag("body")
+class UL() : BodyTag("ul") {
+  fun li(init : LI.() -> Unit) = initTag(LI(), init)
+}
+
+class B() : BodyTag("b")
+class LI() : BodyTag("li")
+class P() : BodyTag("p")
+class H1() : BodyTag("h1")
+class A() : BodyTag("a") {
+  public var href : String?
+    get() = attributes["href"]
+    set(value) {
+       if (value != null) {
+           attributes.put("href", value)
+//         attributes["href"] = value //doesn't work: KT-1355
+       }
+    }
+}
+
+fun html(init : HTML.() -> Unit) : HTML {
+  val html = HTML()
+  html.<!UNRESOLVED_REFERENCE!>init<!>()
+  return html
+}
+
+// An excerpt from the Standard Library
+operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) = this.put(key, value)
+
+fun println(message : Any?) {
+  System.out.println(message)
+}
+
+fun print(message : Any?) {
+  System.out.print(message)
+}
diff --git a/compiler/testData/diagnostics/tests/Casts.fir.kt b/compiler/testData/diagnostics/tests/Casts.fir.kt
new file mode 100644
index 00000000000..54d6ee2d330
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Casts.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+fun test() : Unit {
+  var x : Int? = 0
+  var y : Int = 0
+
+  checkSubtype<Int?>(x)
+  checkSubtype<Int>(y)
+  checkSubtype<Int>(x as Int)
+  checkSubtype<Int>(y as Int)
+  checkSubtype<Int?>(x as Int?)
+  checkSubtype<Int?>(y as Int?)
+  checkSubtype<Int?>(x as? Int)
+  checkSubtype<Int?>(y as? Int)
+  checkSubtype<Int?>(x as? Int?)
+  checkSubtype<Int?>(y as? Int?)
+
+  val s = "" as Any
+  ("" as String?)?.length
+  (data@("" as String?))?.length
+  (@MustBeDocumented()( "" as String?))?.length
+  Unit
+}
diff --git a/compiler/testData/diagnostics/tests/CharacterLiterals.fir.kt b/compiler/testData/diagnostics/tests/CharacterLiterals.fir.kt
new file mode 100644
index 00000000000..fc9280d4f3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/CharacterLiterals.fir.kt
@@ -0,0 +1,13 @@
+fun test(c : Char) {
+  test(<!INFERENCE_ERROR!>''<!>)
+  test('a')
+  test(<!INFERENCE_ERROR!>'aa'<!>)
+  <!INAPPLICABLE_CANDIDATE!>test<!>(<!INFERENCE_ERROR!>'a)<!>
+  <!UNRESOLVED_REFERENCE!>test<!>(<!INFERENCE_ERROR!>'<!>
+  <!UNRESOLVED_REFERENCE!>test<!>(0<!INFERENCE_ERROR!><!SYNTAX!><!>'<!>
+  <!UNRESOLVED_REFERENCE!>test<!>('\n')
+  <!UNRESOLVED_REFERENCE!>test<!>('\\')
+  <!UNRESOLVED_REFERENCE!>test<!>(<!INFERENCE_ERROR!>''<!><!INFERENCE_ERROR!><!SYNTAX!><!>''<!>)
+  test('\'')
+  test('\"')
+}
diff --git a/compiler/testData/diagnostics/tests/CompareToWithErrorType.fir.kt b/compiler/testData/diagnostics/tests/CompareToWithErrorType.fir.kt
new file mode 100644
index 00000000000..de38f681f4b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/CompareToWithErrorType.fir.kt
@@ -0,0 +1,6 @@
+// !WITH_NEW_INFERENCE
+fun test() {
+  if (<!UNRESOLVED_REFERENCE!>x<!> > 0) {
+
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Constants.fir.kt b/compiler/testData/diagnostics/tests/Constants.fir.kt
new file mode 100644
index 00000000000..fd7b1e0f60c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Constants.fir.kt
@@ -0,0 +1,53 @@
+// !CHECK_TYPE
+
+fun varargByte(vararg v: Byte) = v
+
+fun varargShort(vararg v: Short) = v
+
+fun varargInt(vararg v: Int) = v
+
+fun varargLong(vararg v: Long) = v
+
+fun varargFloat(vararg v: Float) = v
+
+fun varargDouble(vararg v: Double) = v
+
+fun <T> testFun(p: T) {}
+
+fun test() {
+    checkSubtype<Byte>(1)
+    checkSubtype<Short>(1)
+    checkSubtype<Int>(1)
+    checkSubtype<Long>(1)
+
+    checkSubtype<Long>(0x001)
+    checkSubtype<Int>(0b001)
+
+    checkSubtype<Double>(0.1)
+    checkSubtype<Float>(0.1.toFloat())
+
+    checkSubtype<Double>(1e5)
+    checkSubtype<Float>(1e-5.toFloat())
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Double>(1)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Float>(1)
+    
+    1 as Byte
+    1 as Int
+    0xff as Long
+    
+    1.1 as Int
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(1.1)
+
+    <!INAPPLICABLE_CANDIDATE!>varargByte<!>(0x77, 1, 3, 200, 0b111)
+    <!INAPPLICABLE_CANDIDATE!>varargShort<!>(0x777, 1, 2, 3, 200000, 0b111)
+    <!INAPPLICABLE_CANDIDATE!>varargInt<!>(0x77777777, 0x7777777777, 1, 2, 3, 2000000000, 0b111)
+    varargLong(0x777777777777, 1, 2, 3, 200000, 0b111)
+    <!INAPPLICABLE_CANDIDATE!>varargFloat<!>(1, 1.0, -0.1, 1e4, 1e-4, -1e4)
+    <!INAPPLICABLE_CANDIDATE!>varargDouble<!>(1, 1.0, -0.1, 1e4, 1e-4, -1e4)
+
+    testFun(1.0)
+    <!INAPPLICABLE_CANDIDATE!>testFun<!><Float>(1.0)
+    testFun(1.0.toFloat())
+    testFun<Float>(1.0.toFloat())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Constructors.fir.kt b/compiler/testData/diagnostics/tests/Constructors.fir.kt
new file mode 100644
index 00000000000..b891906c1c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Constructors.fir.kt
@@ -0,0 +1,35 @@
+open class NoC
+class NoC1 : NoC
+
+class WithC0() : NoC()
+open class WithC1() : NoC
+class NoC2 : WithC1
+class NoC3 : WithC1()
+class WithC2() : WithC1
+
+class WithPC0() {
+}
+
+class WithPC1(a : Int) {
+}
+
+
+class Foo() : WithPC0, <!SYNTAX!>this<!>() {
+
+}
+
+class WithCPI_Dup(x : Int) {
+  var x : Int
+}
+
+class WithCPI(x : Int) {
+  val a = 1
+  val xy : Int = x
+}
+
+class NoCPI {
+  val a = 1
+  var ab = 1
+    get() = 1
+    set(v) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ConstructorsOfPrimitives.fir.kt b/compiler/testData/diagnostics/tests/ConstructorsOfPrimitives.fir.kt
new file mode 100644
index 00000000000..da6e15df17d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ConstructorsOfPrimitives.fir.kt
@@ -0,0 +1,10 @@
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>Double<!>()
+    <!INAPPLICABLE_CANDIDATE!>Float<!>()
+    <!INAPPLICABLE_CANDIDATE!>Long<!>()
+    <!INAPPLICABLE_CANDIDATE!>Int<!>()
+    <!INAPPLICABLE_CANDIDATE!>Short<!>()
+    <!INAPPLICABLE_CANDIDATE!>Byte<!>()
+    <!INAPPLICABLE_CANDIDATE!>Char<!>()
+    <!INAPPLICABLE_CANDIDATE!>Boolean<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/CovariantOverrideType.fir.kt b/compiler/testData/diagnostics/tests/CovariantOverrideType.fir.kt
new file mode 100644
index 00000000000..bbfd7ba22a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/CovariantOverrideType.fir.kt
@@ -0,0 +1,26 @@
+interface A<H> {
+    fun foo() : Int = 1
+    fun foo2() : Int = 1
+    fun foo1() : Int = 1
+    val a : Int
+    val a1 : Int
+    val g : Iterator<H>
+
+    fun <T> g() : T
+    fun <T> g1() : T
+}
+
+abstract class B<H>() : A<H> {
+    override fun foo() {
+    }
+    override fun foo2() : Unit {
+    }
+
+    override val a : Double = 1.toDouble()
+    override val a1 = 1.toDouble()
+
+    abstract override fun <X> g() : Int
+    abstract override fun <X> g1() : List<X>
+
+    abstract override val g : Iterator<Int>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/DefaultValueForParameterInFunctionType.fir.kt b/compiler/testData/diagnostics/tests/DefaultValueForParameterInFunctionType.fir.kt
new file mode 100644
index 00000000000..41c7b8eedbd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DefaultValueForParameterInFunctionType.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun f(x: Int = 0) {}
+
+val inVal: (x: Int = 0)->Unit = {}
+
+fun inParam(fn: (x: Int = 0)->Unit) {}
+
+fun inParamNested(fn1: (fn2: (n: Int = 0)->Unit)->Unit) {}
+
+fun inReturn(): (x: Int = 0)->Unit = {}
+
+class A : (Int)->Unit {
+    override fun invoke(p1: Int) {
+        var lambda: (x: Int = 0)->Unit = {}
+    }
+
+    val prop: (x: Int = 0)->Unit
+        get(): (x: Int = 0)->Unit = {}
+}
diff --git a/compiler/testData/diagnostics/tests/DefaultValuesCheckWithoutBody.fir.kt b/compiler/testData/diagnostics/tests/DefaultValuesCheckWithoutBody.fir.kt
new file mode 100644
index 00000000000..635ae083091
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DefaultValuesCheckWithoutBody.fir.kt
@@ -0,0 +1,9 @@
+interface Inter {
+    fun foo(x: Int = <!UNRESOLVED_REFERENCE!>y<!>, y: Int = x)
+}
+
+abstract class Abst {
+    abstract fun foo(x: Int = <!UNRESOLVED_REFERENCE!>y<!>, y: Int = x)
+}
+
+fun extraDiagnostics(x: Int = <!UNRESOLVED_REFERENCE!>y<!>, y: Int)
diff --git a/compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt b/compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt
new file mode 100644
index 00000000000..5ea18909bba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DefaultValuesTypechecking.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+val x = ""
+
+fun bar(x : Int = "", y : Int = x, z : String = y) {
+
+}
+
+// KT-371 Resolve default parameters for constructors
+
+class A(x : Int = <!UNRESOLVED_REFERENCE!>y<!>, y : Int = x) { // None of the references is resolved, no types checked
+    fun foo(bool: Boolean, a: Int = <!UNRESOLVED_REFERENCE!>b<!>, b: String = a) {}
+}
+
+val z = 3
+
+fun foo(x: Int = <!UNRESOLVED_REFERENCE!>y<!>, y: Int = x, i : Int = z): Int = x + y
diff --git a/compiler/testData/diagnostics/tests/DeferredTypes.fir.kt b/compiler/testData/diagnostics/tests/DeferredTypes.fir.kt
new file mode 100644
index 00000000000..e2b364f0e11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DeferredTypes.fir.kt
@@ -0,0 +1,5 @@
+// NI_EXPECTED_FILE
+
+interface T {
+  val a = <!UNRESOLVED_REFERENCE!>Foo<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/DeprecatedGetSetPropertyDelegateConvention.fir.kt b/compiler/testData/diagnostics/tests/DeprecatedGetSetPropertyDelegateConvention.fir.kt
new file mode 100644
index 00000000000..009457f0ff9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DeprecatedGetSetPropertyDelegateConvention.fir.kt
@@ -0,0 +1,53 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class CustomDelegate {
+    operator fun get(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun set(thisRef: Any?, prop: KProperty<*>, value: String) {}
+}
+
+class OkDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, value: String) {}
+}
+
+class CustomDelegate2 {
+    operator fun get(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun set(thisRef: Any?, prop: KProperty<*>, value: String) {}
+
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): Int = 5
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, value: Int) {}
+}
+
+class CustomDelegate3 {
+    operator fun get(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun set(thisRef: Any?, prop: KProperty<*>, value: String) {}
+}
+
+operator fun OkDelegate.get(thisRef: Any?, prop: KProperty<*>): Int = 4
+operator fun OkDelegate.set(thisRef: Any?, prop: KProperty<*>, value: Int) {}
+
+operator fun CustomDelegate3.getValue(thisRef: Any?, prop: KProperty<*>): Int = 4
+operator fun CustomDelegate3.setValue(thisRef: Any?, prop: KProperty<*>, value: Int) {}
+
+class Example {
+
+    var a by CustomDelegate()
+    val aval by CustomDelegate()
+    var b by OkDelegate()
+    var c by CustomDelegate2()
+    var d by CustomDelegate3()
+
+    fun test() {
+        requireString(a)
+        requireString(aval)
+        requireString(b)
+        requireInt(c)
+        requireInt(d)
+    }
+
+    fun requireString(s: String) {}
+    fun requireInt(n: Int) {}
+
+}
diff --git a/compiler/testData/diagnostics/tests/DeprecatedUnaryOperatorConventions.fir.kt b/compiler/testData/diagnostics/tests/DeprecatedUnaryOperatorConventions.fir.kt
new file mode 100644
index 00000000000..36926e1421d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DeprecatedUnaryOperatorConventions.fir.kt
@@ -0,0 +1,33 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Example {
+    operator fun plus(): String = ""
+    operator fun unaryPlus(): Int = 0
+}
+
+class ExampleDeprecated {
+    operator fun plus(): String = ""
+}
+
+operator fun String.plus(): String = this
+operator fun String.unaryPlus(): Int = 0
+
+fun test() {
+    requireInt(+ "")
+    requireInt(+ Example())
+    requireString(<!INAPPLICABLE_CANDIDATE!>+<!> ExampleDeprecated())
+}
+
+fun requireInt(n: Int) {}
+fun requireString(s: String) {}
+
+class Example2 {
+    operator fun plus() = this
+    operator fun minus() = this
+
+    fun test() {
+        <!INAPPLICABLE_CANDIDATE!>+<!>this
+        <!UNRESOLVED_REFERENCE!>-<!>this
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/DiamondFunction.fir.kt b/compiler/testData/diagnostics/tests/DiamondFunction.fir.kt
new file mode 100644
index 00000000000..0d8b9a77755
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DiamondFunction.fir.kt
@@ -0,0 +1,9 @@
+interface Base {
+    fun f() = 1
+}
+    
+open class Left() : Base
+
+interface Right : Base
+
+class Diamond() : Left(), Right
diff --git a/compiler/testData/diagnostics/tests/DiamondFunctionGeneric.fir.kt b/compiler/testData/diagnostics/tests/DiamondFunctionGeneric.fir.kt
new file mode 100644
index 00000000000..d84e34a40a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DiamondFunctionGeneric.fir.kt
@@ -0,0 +1,9 @@
+interface Base<P> {
+    fun f() = 1
+}
+    
+open class Left<P>() : Base<P>
+
+interface Right<P> : Base<P>
+
+class Diamond<P>() : Left<P>(), Right<P>
diff --git a/compiler/testData/diagnostics/tests/DiamondProperty.fir.kt b/compiler/testData/diagnostics/tests/DiamondProperty.fir.kt
new file mode 100644
index 00000000000..5a93ad88daa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/DiamondProperty.fir.kt
@@ -0,0 +1,11 @@
+interface Base {
+    var v : Int
+        get() = 1
+        set(v) {}
+}
+    
+open class Left() : Base
+
+interface Right : Base
+
+class Diamond() : Left(), Right
diff --git a/compiler/testData/diagnostics/tests/Dollar.fir.kt b/compiler/testData/diagnostics/tests/Dollar.fir.kt
new file mode 100644
index 00000000000..ca13dc9c9d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Dollar.fir.kt
@@ -0,0 +1,12 @@
+package dollar
+
+open class `$$$$$`() {
+}
+open class `$`() {
+}
+open class `$$`(`$$$$` : `$$$$$`?) : `$`() {
+    val `$$$` : `$$$$$`? = `$$$$`
+    open public fun `$$$$$$`() : `$$$$$`? {
+        return `$$$`
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/EnumEntryAsType.fir.kt b/compiler/testData/diagnostics/tests/EnumEntryAsType.fir.kt
new file mode 100644
index 00000000000..cf9bf545942
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/EnumEntryAsType.fir.kt
@@ -0,0 +1,55 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+enum class Color {
+    RED {
+        fun <T : RED> simpleName(): RED = null!!
+    }
+}
+
+class MyColor(val x: Color.RED, y: Color.RED) : Color.RED {
+
+    var z: Color.RED = Color.RED
+    set(arg: Color.RED) { z = arg }
+
+    fun foo(arg: Color.RED): Color.RED = arg
+
+    fun bar(): Color.RED {
+        class Local : Color.RED
+        fun local(arg: Color.RED): Color.RED = arg
+        val temp: Color.RED = Color.RED
+        temp as? Color.RED
+        if (temp is Color.RED) {
+        return temp as Color.RED
+    }
+        val obj = object : Color.RED {}
+        if (obj is Color.RED) {
+        return obj
+    }
+        return Color.RED
+    }
+}
+
+fun create(): Array<Color.RED>? = null
+
+interface Your<T : Color.RED>
+
+class His : Your<Color.RED>
+
+fun <T : Color.RED> otherCreate(): Array<T>? = null
+
+typealias RedAlias = Color.RED
+
+typealias ArrayOfEnumEntry = Array<Color.RED>
+
+typealias ArrayOfEnumEntryAlias = Array<RedAlias>
+
+fun <T> bar(a: Any): T = a as T
+
+fun <T> foo() {
+    foo<Color.RED>()
+    foo<RedAlias>()
+    bar<Color.RED>(Color.RED)
+}
+
+fun Array<Color.RED>.foo(entries: Array<Color.RED>): Array<Color.RED> = null!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ExtensionCallInvoke.fir.kt b/compiler/testData/diagnostics/tests/ExtensionCallInvoke.fir.kt
new file mode 100644
index 00000000000..a4092148fba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ExtensionCallInvoke.fir.kt
@@ -0,0 +1,7 @@
+fun bar(doIt: Int.() -> Int) {
+    1.<!UNRESOLVED_REFERENCE!>doIt<!>()
+    1?.<!UNRESOLVED_REFERENCE!>doIt<!>()
+    val i: Int? = 1
+    i.<!UNRESOLVED_REFERENCE!>doIt<!>()
+    i?.<!UNRESOLVED_REFERENCE!>doIt<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/ExternalAccessors.fir.kt b/compiler/testData/diagnostics/tests/ExternalAccessors.fir.kt
new file mode 100644
index 00000000000..55bea112b91
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ExternalAccessors.fir.kt
@@ -0,0 +1,19 @@
+// See KT-13997
+
+class Foo {
+    var bar: Int // Ok
+        external get
+        external set
+}
+
+class Bar {
+    val foo: Int // Ok
+        external get
+
+    var baz: Int
+        external get
+
+    var gav: Int
+        external set
+}
+
diff --git a/compiler/testData/diagnostics/tests/ExternalAndAbstract.fir.kt b/compiler/testData/diagnostics/tests/ExternalAndAbstract.fir.kt
new file mode 100644
index 00000000000..fa3f698fe67
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ExternalAndAbstract.fir.kt
@@ -0,0 +1,9 @@
+abstract class A {
+    abstract val x : Int
+        external get
+}
+
+interface B {
+    val x: Int
+        external get
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ForRangeConventions.fir.kt b/compiler/testData/diagnostics/tests/ForRangeConventions.fir.kt
new file mode 100644
index 00000000000..87cad73a5f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ForRangeConventions.fir.kt
@@ -0,0 +1,93 @@
+// !CHECK_TYPE
+
+import java.util.*;
+
+class NotRange1() {
+
+}
+
+abstract class NotRange2() {
+  abstract operator fun iterator() : Unit
+}
+
+abstract class ImproperIterator1 {
+  abstract operator fun hasNext() : Boolean
+}
+
+abstract class NotRange3() {
+  abstract operator fun iterator() : ImproperIterator1
+}
+
+abstract class ImproperIterator2 {
+  abstract operator fun next() : Boolean
+}
+
+abstract class NotRange4() {
+  abstract operator fun iterator() : ImproperIterator2
+}
+
+abstract class ImproperIterator3 {
+  abstract operator fun hasNext() : Int
+  abstract operator fun next() : Int
+}
+
+abstract class NotRange5() {
+  abstract operator fun iterator() : ImproperIterator3
+}
+
+abstract class AmbiguousHasNextIterator {
+  abstract operator fun hasNext() : Boolean
+  val hasNext : Boolean get() = false
+  abstract operator fun next() : Int
+}
+
+abstract class NotRange6() {
+  abstract operator fun iterator() : AmbiguousHasNextIterator
+}
+
+abstract class ImproperIterator4 {
+  val hasNext : Int get() = 1
+  abstract operator fun next() : Int
+}
+
+abstract class NotRange7() {
+  abstract operator fun iterator() : ImproperIterator3
+}
+
+abstract class GoodIterator {
+  abstract operator fun hasNext() : Boolean
+  abstract operator fun next() : Int
+}
+
+abstract class Range0() {
+  abstract operator fun iterator() : GoodIterator
+}
+
+abstract class Range1() {
+  abstract operator fun iterator() : Iterator<Int>
+}
+
+abstract class ImproperIterator5 {
+    abstract val String.hasNext : Boolean
+    abstract operator fun next() : Int
+}
+
+abstract class NotRange8() {
+    abstract operator fun iterator() : ImproperIterator5
+}
+
+
+fun test(notRange1: NotRange1, notRange2: NotRange2, notRange3: NotRange3, notRange4: NotRange4, notRange5: NotRange5, notRange6: NotRange6, notRange7: NotRange7, notRange8: NotRange8, range0: Range0, range1: Range1) {
+  <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (i in notRange1)<!>;
+  <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (i in notRange2)<!>;
+  <!UNRESOLVED_REFERENCE!>for (i in notRange3)<!>;
+  <!UNRESOLVED_REFERENCE!>for (i in notRange4)<!>;
+  for (i in notRange5);
+  for (i in notRange6);
+  for (i in notRange7);
+  <!UNRESOLVED_REFERENCE!>for (i in notRange8)<!>;
+  for (i in range0);
+  for (i in range1);
+
+  for (i in (checkSubtype<List<Int>>(ArrayList<Int>())));
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/FreeFunctionCalledAsExtension.fir.kt b/compiler/testData/diagnostics/tests/FreeFunctionCalledAsExtension.fir.kt
new file mode 100644
index 00000000000..22b2715d38f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/FreeFunctionCalledAsExtension.fir.kt
@@ -0,0 +1,13 @@
+fun foo(a: (String) -> Unit) {
+    "".<!UNRESOLVED_REFERENCE!>a<!>()
+}
+
+
+
+interface A : (String) -> Unit {}
+
+fun foo(a: @ExtensionFunctionType A) {
+    // @Extension annotation on an unrelated type shouldn't have any effect on this diagnostic.
+    // Only kotlin.Function{n} type annotated with @Extension should
+    "".<!UNRESOLVED_REFERENCE!>a<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/FunctionCalleeExpressions.fir.kt b/compiler/testData/diagnostics/tests/FunctionCalleeExpressions.fir.kt
new file mode 100644
index 00000000000..ba26cc68507
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/FunctionCalleeExpressions.fir.kt
@@ -0,0 +1,84 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+package foo
+
+fun Any.foo() : () -> Unit {
+  return {}
+}
+
+fun Any.foo1() : (i : Int) -> Unit {
+  return {}
+}
+
+fun foo2() : (i : () -> Unit) -> Unit {
+  return {}
+}
+
+fun <T> fooT1(t : T) : () -> T {
+  return {t}
+}
+
+fun <T> fooT2() : (t : T) -> T {
+  return {it}
+}
+
+fun main(args : Array<String>) {
+    args.foo()()
+    <!INAPPLICABLE_CANDIDATE!>args.foo1()()<!>
+    <!INAPPLICABLE_CANDIDATE!><!UNRESOLVED_REFERENCE!>a<!>.foo1()()<!>
+    <!UNRESOLVED_REFERENCE!>a<!>.foo1()(<!UNRESOLVED_REFERENCE!>a<!>)
+
+    args.foo1()(1)
+    <!INAPPLICABLE_CANDIDATE!>args.foo1()("1")<!>
+    <!INAPPLICABLE_CANDIDATE!><!UNRESOLVED_REFERENCE!>a<!>.foo1()("1")<!>
+    <!UNRESOLVED_REFERENCE!>a<!>.foo1()(<!UNRESOLVED_REFERENCE!>a<!>)
+
+    foo2()({})
+    <!INAPPLICABLE_CANDIDATE!>foo2<!>(){}
+    (foo2()){}
+    <!INAPPLICABLE_CANDIDATE!>(foo2()){x -> }<!>
+    <!INAPPLICABLE_CANDIDATE!>foo2()({x -> })<!>
+
+    val a = fooT1(1)()
+    checkSubtype<Int>(a)
+
+    val b = fooT2<Int>()(1)
+    checkSubtype<Int>(b)
+    fooT2()(1) // : Any?
+
+    <!UNRESOLVED_REFERENCE!>1()<!>
+    <!UNRESOLVED_REFERENCE!>1{}<!>
+    <!UNRESOLVED_REFERENCE!>1(){}<!>
+}
+
+fun f() :  Int.() -> Unit = {}
+
+fun main1() {
+    1.<!UNRESOLVED_REFERENCE!>(fun Int.() = 1)()<!>;
+    <!UNRESOLVED_REFERENCE!>{1}()<!>;
+    <!UNRESOLVED_REFERENCE!>(fun (x : Int) = x)(1)<!>
+    1.<!UNRESOLVED_REFERENCE!>(fun Int.(x : Int) = x)(1)<!>;
+    l@<!UNRESOLVED_REFERENCE!>{1}()<!>
+    1.<!UNRESOLVED_REFERENCE!>((fun Int.() = 1))()<!>
+    1.<!UNRESOLVED_REFERENCE!>(f())()<!>
+    1.<!UNRESOLVED_REFERENCE!>if(true){f()}else{f()}()<!>
+    1.<!UNRESOLVED_REFERENCE!>if(true)(fun Int.() {})else{f()}()<!>
+
+    1.<!UNRESOLVED_REFERENCE!>"sdf"()<!>
+
+    1."sdf"
+    1.{}
+    1.if (true) {}
+}
+
+fun test() {
+    <!UNRESOLVED_REFERENCE!>{x : Int -> 1}()<!>;
+    <!UNRESOLVED_REFERENCE!>(fun Int.() = 1)()<!>
+    "sd".<!UNRESOLVED_REFERENCE!>(fun Int.() = 1)()<!>
+    val i : Int? = null
+    i.<!UNRESOLVED_REFERENCE!>(fun Int.() = 1)()<!>;
+    <!UNRESOLVED_REFERENCE!>{}<Int>()<!>
+    1?.<!UNRESOLVED_REFERENCE!>(fun Int.() = 1)()<!>
+    1.<!UNRESOLVED_REFERENCE!>{}()<!>
+}
diff --git a/compiler/testData/diagnostics/tests/FunctionParameterWithoutType.fir.kt b/compiler/testData/diagnostics/tests/FunctionParameterWithoutType.fir.kt
new file mode 100644
index 00000000000..770829cde47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/FunctionParameterWithoutType.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+fun test(a) {
+
+}
+
+class A(a<!SYNTAX!><!>)
+
+val bar = fun(a){}
+
+val la = { a -> }
+val las = { a: Int -> }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/FunctionReturnTypes.fir.kt b/compiler/testData/diagnostics/tests/FunctionReturnTypes.fir.kt
new file mode 100644
index 00000000000..8d72e507236
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/FunctionReturnTypes.fir.kt
@@ -0,0 +1,209 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+
+fun none() {}
+
+fun unitEmptyInfer() {}
+fun unitEmpty() : Unit {}
+fun unitEmptyReturn() : Unit {return}
+fun unitIntReturn() : Unit {return 1}
+fun unitUnitReturn() : Unit {return Unit}
+fun test1() : Any = {return}
+fun test2() : Any = a@ {return@a 1}
+fun test3() : Any { return }
+fun test4(): ()-> Unit = { return@test4 }
+fun test5(): Any = l@{ return@l }
+fun test6(): Any = {return 1}
+
+fun bbb() {
+    return 1
+}
+
+fun foo(expr: StringBuilder): Int {
+    val c = 'a'
+    when(c) {
+        0.toChar() -> throw Exception("zero")
+        else -> throw Exception("nonzero" + c)
+    }
+}
+
+
+fun unitShort() : Unit = Unit
+fun unitShortConv() : Unit = 1
+fun unitShortNull() : Unit = null
+
+fun intEmpty() : Int {}
+fun intShortInfer() = 1
+fun intShort() : Int = 1
+//fun intBlockInfer()  {1}
+fun intBlock() : Int {return 1}
+fun intBlock1() : Int {1}
+
+fun intString(): Int = "s"
+fun intFunctionLiteral(): Int = { 10 }
+
+fun blockReturnUnitMismatch() : Int {return}
+fun blockReturnValueTypeMismatch() : Int {return 3.4}
+fun blockReturnValueTypeMatch() : Int {return 1}
+fun blockReturnValueTypeMismatchUnit() : Int {return Unit}
+
+fun blockAndAndMismatch() : Int {
+    true && false
+    }
+fun blockAndAndMismatch1() : Int {
+    return true && false
+}
+fun blockAndAndMismatch2() : Int {
+    (return true) && (return false)
+}
+
+fun blockAndAndMismatch3() : Int {
+    true || false
+    }
+fun blockAndAndMismatch4() : Int {
+    return true || false
+}
+fun blockAndAndMismatch5() : Int {
+    (return true) || (return false)
+}
+fun blockReturnValueTypeMatch1() : Int {
+    return if (1 > 2) 1.0 else 2.0
+}
+fun blockReturnValueTypeMatch2() : Int {
+    return if (1 > 2) 1
+}
+fun blockReturnValueTypeMatch3() : Int {
+    return if (1 > 2) else 1
+}
+fun blockReturnValueTypeMatch4() : Int {
+    if (1 > 2)
+        return 1.0
+    else return 2.0
+}
+fun blockReturnValueTypeMatch5() : Int {
+    if (1 > 2)
+        return 1.0
+    return 2.0
+}
+fun blockReturnValueTypeMatch6() : Int {
+    if (1 > 2)
+    else return 1.0
+    return 2.0
+}
+fun blockReturnValueTypeMatch7() : Int {
+    if (1 > 2)
+    1.0
+    else 2.0
+    }
+fun blockReturnValueTypeMatch8() : Int {
+    if (1 > 2)
+    1.0
+    else 2.0
+    return 1
+}
+fun blockReturnValueTypeMatch9() : Int {
+    if (1 > 2)
+    1.0
+    }
+fun blockReturnValueTypeMatch10() : Int {
+    return if (1 > 2)
+    1
+}
+fun blockReturnValueTypeMatch11() : Int {
+    if (1 > 2)
+    else 1.0
+    }
+fun blockReturnValueTypeMatch12() : Int {
+    if (1 > 2)
+        return 1
+    else return 1.0
+}
+fun blockNoReturnIfValDeclaration(): Int {
+    val x = 1
+    }
+fun blockNoReturnIfEmptyIf(): Int {
+    if (1 < 2) {} else {}
+    }
+fun blockNoReturnIfUnitInOneBranch(): Int {
+    if (1 < 2) {
+        return 1
+    } else {
+        if (3 < 4) {
+        } else {
+            return 2
+        }
+    }
+    }
+fun nonBlockReturnIfEmptyIf(): Int = if (1 < 2) {} else {}
+fun nonBlockNoReturnIfUnitInOneBranch(): Int = if (1 < 2) {} else 2
+
+val a = return 1
+
+class A() {
+}
+fun illegalConstantBody(): Int = "s"
+fun illegalConstantBlock(): String {
+    return 1
+}
+fun illegalIfBody(): Int =
+        if (1 < 2) 'a' else { 1.0 }
+fun illegalIfBlock(): Boolean {
+    if (1 < 2)
+        return false
+    else { return 1 }
+}
+fun illegalReturnIf(): Char {
+    return if (1 < 2) 'a' else { 1 }
+}
+
+fun returnNothing(): Nothing {
+    throw 1
+}
+fun f(): Int {
+    if (1 < 2) { return 1 } else returnNothing()
+}
+
+fun f1(): Int = if (1 < 2) 1 else returnNothing()
+
+public fun f2() = 1
+class B() {
+    protected fun f() = "ss"
+}
+
+fun testFunctionLiterals() {
+    val endsWithVarDeclaration : () -> Boolean = {
+        val x = 2
+    }
+
+    val endsWithAssignment: () -> Int = {
+        var x = 1
+        x = 333
+    }
+
+    val endsWithReAssignment: () -> Int = {
+        var x = 1
+        x += 333
+    }
+
+    val endsWithFunDeclaration : () -> String = {
+        var x = 1
+        x = 333
+        fun meow() : Unit {}
+    }
+
+    val endsWithObjectDeclaration : () -> Int = {
+        var x = 1
+        x = 333
+        object A {}
+    }
+
+    val expectedUnitReturnType1: () -> Unit = {
+        val x = 1
+    }
+
+    val expectedUnitReturnType2: () -> Unit = {
+        fun meow() : Unit {}
+        object A {}
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/GenericArgumentConsistency.fir.kt b/compiler/testData/diagnostics/tests/GenericArgumentConsistency.fir.kt
new file mode 100644
index 00000000000..d5421d842e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/GenericArgumentConsistency.fir.kt
@@ -0,0 +1,43 @@
+// FILE: b.kt
+interface A<in T> {}
+interface B<T> : A<Int> {}
+interface C<T> : B<T>, A<T> {}
+interface C1<T> : B<T>, A<Any> {}
+interface D : C<Boolean>, B<Double>{}
+
+interface A1<out T> {}
+interface B1 : A1<Int> {}
+interface B2 : A1<Any>, B1 {}
+
+interface BA1<T> {}
+interface BB1 : BA1<Int> {}
+interface BB2 : BA1<Any>, BB1 {}
+
+
+// FILE: b.kt
+package x
+    interface AA1<out T> {}
+    interface AB1 : AA1<Int> {}
+    interface AB3 : AA1<Comparable<Int>> {}
+    interface AB2 : AA1<Number>, AB1, AB3 {}
+
+// FILE: b.kt
+package x2
+    interface AA1<out T> {}
+    interface AB1 : AA1<Any> {}
+    interface AB3 : AA1<Comparable<Int>> {}
+    interface AB2 : AA1<Number>, AB1, AB3 {}
+
+// FILE: b.kt
+package x3
+    interface AA1<in T> {}
+    interface AB1 : AA1<Any> {}
+    interface AB3 : AA1<Comparable<Int>> {}
+    interface AB2 : AA1<Number>, AB1, AB3 {}
+
+// FILE: b.kt
+package sx2
+    interface AA1<in T> {}
+    interface AB1 : AA1<Int> {}
+    interface AB3 : AA1<Comparable<Int>> {}
+    interface AB2 : AA1<Number>, AB1, AB3 {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/GenericFunctionIsLessSpecific.fir.kt b/compiler/testData/diagnostics/tests/GenericFunctionIsLessSpecific.fir.kt
new file mode 100644
index 00000000000..67150ef3926
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/GenericFunctionIsLessSpecific.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+// A generic funciton is always less specific than a non-generic one
+fun <T> foo(t : T) : Unit {}
+fun foo(i : Int) : Int = 1
+
+fun test() {
+    checkSubtype<Int>(foo(1))
+    checkSubtype<Unit>(foo("s"))
+}
diff --git a/compiler/testData/diagnostics/tests/IdentityComparisonWithPrimitives.fir.kt b/compiler/testData/diagnostics/tests/IdentityComparisonWithPrimitives.fir.kt
new file mode 100644
index 00000000000..6b1c6f1338a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/IdentityComparisonWithPrimitives.fir.kt
@@ -0,0 +1,81 @@
+val z: Boolean = true
+val b: Byte = 0
+val s: Short = 0
+val i: Int = 0
+val j: Long = 0L
+val f: Float = 0.0f
+val d: Double = 0.0
+val c: Char = '0'
+
+val nz: Boolean? = true
+val nb: Byte? = 0
+val ns: Short? = 0
+val ni: Int? = 0
+val nj: Long? = 0L
+val nf: Float? = 0.0f
+val nd: Double? = 0.0
+val nc: Char? = '0'
+
+val n: Number = 0
+val nn: Number? = 0
+val a: Any = 0
+val na: Any? = 0
+
+// Identity for primitive values of same type
+val test_zz = z === z || z !== z
+val test_bb = b === b || b !== b
+val test_ss = s === s || s !== s
+val test_ii = i === i || i !== i
+val test_jj = j === j || j !== j
+val test_ff = f === f || f !== f
+val test_dd = d === d || d !== d
+val test_cc = c === c || c !== c
+
+// Identity for primitive values of different types (no extra error)
+val test_zb = z === b || z !== b
+
+// Primitive vs nullable
+val test_znz = z === nz || nz === z || z !== nz || nz !== z
+val test_bnb = b === nb || nb === b || b !== nb || nb !== b
+val test_sns = s === ns || ns === s || s !== ns || ns !== s
+val test_ini = i === ni || ni === i || i !== ni || ni !== i
+val test_jnj = j === nj || nj === j || j !== nj || nj !== j
+val test_fnf = f === nf || nf === f || f !== nf || nf !== f
+val test_dnd = d === nd || nd === d || d !== nd || nd !== d
+val test_cnc = c === nc || nc === c || c !== nc || nc !== c
+
+// Primitive number vs Number
+val test_bn = b === n || n === b || b !== n || n !== b
+val test_sn = s === n || n === s || s !== n || n !== s
+val test_in = i === n || n === i || i !== n || n !== i
+val test_jn = j === n || n === j || j !== n || n !== j
+val test_fn = f === n || n === f || f !== n || n !== f
+val test_dn = d === n || n === d || d !== n || n !== d
+
+// Primitive number vs Number?
+val test_bnn = b === nn || nn === b || b !== nn || nn !== b
+val test_snn = s === nn || nn === s || s !== nn || nn !== s
+val test_inn = i === nn || nn === i || i !== nn || nn !== i
+val test_jnn = j === nn || nn === j || j !== nn || nn !== j
+val test_fnn = f === nn || nn === f || f !== nn || nn !== f
+val test_dnn = d === nn || nn === d || d !== nn || nn !== d
+
+// Primitive vs Any
+val test_za = z === a || a === z || z !== a || a !== z
+val test_ba = b === a || a === b || b !== a || a !== b
+val test_sa = s === a || a === s || s !== a || a !== s
+val test_ia = i === a || a === i || i !== a || a !== i
+val test_ja = j === a || a === j || j !== a || a !== j
+val test_fa = f === a || a === f || f !== a || a !== f
+val test_da = d === a || a === d || d !== a || a !== d
+val test_ca = c === a || a === c || c !== a || a !== c
+
+// Primitive vs Any?
+val test_zna = z === na || na === z || z !== na || na !== z
+val test_bna = b === na || na === b || b !== na || na !== b
+val test_sna = s === na || na === s || s !== na || na !== s
+val test_ina = i === na || na === i || i !== na || na !== i
+val test_jna = j === na || na === j || j !== na || na !== j
+val test_fna = f === na || na === f || f !== na || na !== f
+val test_dna = d === na || na === d || d !== na || na !== d
+val test_cna = c === na || na === c || c !== na || na !== c
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/IncDec.fir.kt b/compiler/testData/diagnostics/tests/IncDec.fir.kt
new file mode 100644
index 00000000000..71ddec78514
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/IncDec.fir.kt
@@ -0,0 +1,46 @@
+class IncDec() {
+  operator fun inc() : IncDec = this
+  operator fun dec() : IncDec = this
+}
+
+fun testIncDec() {
+  var x = IncDec()
+  x++
+  ++x
+  x--
+  --x
+  x = x++
+  x = x--
+  x = ++x
+  x = --x
+}
+
+class WrongIncDec() {
+  operator fun inc() : Int = 1
+  operator fun dec() : Int = 1
+}
+
+fun testWrongIncDec() {
+  var x = WrongIncDec()
+  x++
+  <!AMBIGUITY!>++<!>x
+  x<!AMBIGUITY!>--<!>
+  <!AMBIGUITY!>--<!>x
+}
+
+class UnitIncDec() {
+  operator fun inc() : Unit {}
+  operator fun dec() : Unit {}
+}
+
+fun testUnitIncDec() {
+  var x = UnitIncDec()
+  x++
+  ++x
+  x--
+  --x
+  x = x++
+  x = x--
+  x = ++x
+  x = --x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/IncorrectCharacterLiterals.fir.kt b/compiler/testData/diagnostics/tests/IncorrectCharacterLiterals.fir.kt
new file mode 100644
index 00000000000..ae99eb93871
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/IncorrectCharacterLiterals.fir.kt
@@ -0,0 +1,37 @@
+// http://youtrack.jetbrains.net/issue/KT-451
+// KT-451 Incorrect character literals cause assertion failures
+
+fun ff() {
+    val b = <!INFERENCE_ERROR, INFERENCE_ERROR!>''<!>
+    val c = <!INFERENCE_ERROR, INFERENCE_ERROR!>'23'<!>
+    val d = <!INFERENCE_ERROR, INFERENCE_ERROR!>'a<!>
+    val e = <!INFERENCE_ERROR, INFERENCE_ERROR!>'ab<!>
+    val f = <!INFERENCE_ERROR, INFERENCE_ERROR!>'\'<!>
+}
+
+fun test() {
+    'a'
+    '\n'
+    '\t'
+    '\b'
+    '\r'
+    '\"'
+    '\''
+    '\\'
+    '\$'
+    <!INFERENCE_ERROR!>'\x'<!>
+    <!INFERENCE_ERROR!>'\123'<!>
+    <!INFERENCE_ERROR!>'\ra'<!>
+    <!INFERENCE_ERROR!>'\000'<!>
+    <!INFERENCE_ERROR!>'\000'<!>
+    '\u0000'
+    '\u000a'
+    '\u000A'
+    <!INFERENCE_ERROR!>'\u'<!>
+    <!INFERENCE_ERROR!>'\u0'<!>
+    <!INFERENCE_ERROR!>'\u00'<!>
+    <!INFERENCE_ERROR!>'\u000'<!>
+    <!INFERENCE_ERROR!>'\u000z'<!>
+    <!INFERENCE_ERROR!>'\\u000'<!>
+    <!INFERENCE_ERROR, INFERENCE_ERROR!>'\'<!>
+}
diff --git a/compiler/testData/diagnostics/tests/InferNullabilityInThenBlock.fir.kt b/compiler/testData/diagnostics/tests/InferNullabilityInThenBlock.fir.kt
new file mode 100644
index 00000000000..81dbd493513
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/InferNullabilityInThenBlock.fir.kt
@@ -0,0 +1,9 @@
+fun ff(a: String) = 1
+
+fun gg() {
+    val a: String? = ""
+
+    if (a != null) {
+        ff(a)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/Infix.fir.kt b/compiler/testData/diagnostics/tests/Infix.fir.kt
new file mode 100644
index 00000000000..f852458c439
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Infix.fir.kt
@@ -0,0 +1,38 @@
+class Pair<out A, out B>(val first: A, val second: B)
+
+class Example {
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun to(other: Example) = Pair(this, other)<!>
+    fun toNonInfix(other: Example) = Pair(this, other)
+}
+
+infix fun Example.toExt(other: Example) = Pair(this, other)
+fun Example.toExtNonInfix(other: Example) = Pair(this, other)
+
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun Example.toExtWithExtraParams(other: Example, blah: Int = 0) = Pair(this, other)<!>
+fun Example.toExtNonInfixWithExtraParams(other: Example, blah: Int = 0) = Pair(this, other)
+
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun Example.toExtDefaultValues(other: Example? = null, blah: Int = 0) = Pair(this, other)<!>
+fun Example.toExtNonInfixDefaultValues(other: Example? = null, blah: Int = 0) = Pair(this, other)
+
+fun Example.withLambda(f: () -> Unit) = Pair(this, f)
+
+fun test() {
+    Example() to Example()
+    Example() toNonInfix Example()
+    Example().toNonInfix(Example())
+
+    val a = Example()
+    val b = Example()
+
+    a toExt b
+    a toExtNonInfix b
+    a.toExtNonInfix(b)
+
+    a toExtWithExtraParams b
+    a toExtNonInfixWithExtraParams b
+
+    a toExtDefaultValues b
+    a toExtNonInfixDefaultValues b
+
+    a withLambda { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/InfixModifierApplicability.fir.kt b/compiler/testData/diagnostics/tests/InfixModifierApplicability.fir.kt
new file mode 100644
index 00000000000..e276ad484b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/InfixModifierApplicability.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Pair<A, B>(val a: A, val b: B)
+infix fun <A, B> A.to(that: B): Pair<A, B> = Pair(this, that)
+
+// OK
+infix fun String.ok1(o: String) {}
+class OkTest {
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun ok2(o: String) {}<!>
+    infix fun String.ok3(o: String) {}
+}
+
+// Errors
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun String.e1(o: String, o2: String? = null) = o<!>
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun String.e2(o: String = "", o2: String? = null) = o<!>
+
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun e3() {}<!>
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun e4(s: String) {}<!>
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun String.e5() {}<!>
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun String.e6(a: Int, b: Int) {}<!>
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun e7(a: Int, b: Int) {}<!>
+
+class Example {
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun e8(s: String, a: Int = 0) {}<!>
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun e9(s: String, a: Int) {}<!>
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun e10() {}<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/InvokeAndRecursiveResolve.fir.kt b/compiler/testData/diagnostics/tests/InvokeAndRecursiveResolve.fir.kt
new file mode 100644
index 00000000000..1a8d787d47f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/InvokeAndRecursiveResolve.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+fun test() = 3
+
+fun <T> proxy(t: T) = t
+
+class A {
+    val test = test()
+}
+
+class B {
+    val test = proxy(test())
+}
+
+class C {
+    val bar = test()
+    val test = <!UNRESOLVED_REFERENCE!>bar<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/IsExpressions.fir.kt b/compiler/testData/diagnostics/tests/IsExpressions.fir.kt
new file mode 100644
index 00000000000..a12b3ef9fe4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/IsExpressions.fir.kt
@@ -0,0 +1,26 @@
+// FILE: KotlinFile.kt
+
+fun test() {
+   if (1 is Int) {
+     if (1 is Boolean) {
+
+     }
+   }
+
+   A.create() is A
+   A.create() is A?
+
+   <!UNRESOLVED_REFERENCE!>unresolved<!> is A
+   <!UNRESOLVED_REFERENCE!>unresolved<!> is A?
+
+   val x = foo()
+   x as String
+   x is String
+}
+
+fun foo(): Any = ""
+
+// FILE: A.java
+class A {
+    static A create() { return null; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/LValueAssignment.fir.kt b/compiler/testData/diagnostics/tests/LValueAssignment.fir.kt
new file mode 100644
index 00000000000..89c5d1c5d1c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/LValueAssignment.fir.kt
@@ -0,0 +1,143 @@
+package lvalue_assignment
+
+open class B() {
+    var b: Int = 2
+    val c: Int = 34
+}
+
+class C() : B() {
+    var x = 4
+    fun foo(c: C) {
+        this.x = 34
+        this.b = 123
+        super.b = 23
+        this.c = 34
+        super.c = 3535 //repeat for 'c'
+
+        getInt() = 12
+    }
+
+    fun foo1(c: C) {
+        super.c = 34
+    }
+
+    fun bar(c: C) {
+        this = c  //should be an error
+    }
+}
+
+fun getInt() = 0
+
+class D() {
+    inner class B() {
+        fun foo() {
+            this@D = D()
+        }
+    }
+}
+
+fun foo(): Unit {}
+
+fun cannotBe() {
+    var i: Int = 5
+
+    <!UNRESOLVED_REFERENCE!>z<!> = 30;
+    "" = "";
+    foo() = Unit;
+
+    (i as Int) = 34
+    (i is Int) = false
+    A() = A()
+    5 = 34
+}
+
+fun canBe(i0: Int, j: Int) {
+    var i = i0
+    (label@ i) = 34
+
+    (label@ j) = 34 //repeat for j
+
+    val a = A()
+    (l@ a.a) = 3894
+}
+
+fun canBe2(j: Int) {
+    (label@ j) = 34
+}
+
+class A() {
+    var a: Int = 3
+}
+
+class Test() {
+    fun testIllegalValues() {
+        <!VARIABLE_EXPECTED!>1<!> += 23
+        (l@ <!VARIABLE_EXPECTED!>1<!>) += 23
+
+        <!VARIABLE_EXPECTED!>getInt()<!> += 343
+        (f@ <!VARIABLE_EXPECTED!>getInt()<!>) += 343
+
+        1++
+        (r@ 1)++
+
+        getInt()++
+        (m@ getInt())++
+
+        this<!UNRESOLVED_REFERENCE!>++<!>
+
+        var s : String = "r"
+        s += "ss"
+        s += this
+        s += (a@ 2)
+    }
+
+    fun testIncompleteSyntax() {
+        val s = "s"
+        <!UNRESOLVED_REFERENCE!>++<!>s.<!SYNTAX!><!>
+    }
+
+    fun testVariables() {
+        var a: Int = 34
+        val b: Int = 34
+
+        a += 34
+        (l@ a) += 34
+
+        <!VARIABLE_EXPECTED!>b<!> += 34
+
+        a++
+        (l@ a)++
+        (a)++
+    }
+
+    fun testVariables1() {
+        val b: Int = 34
+
+        (l@ <!VARIABLE_EXPECTED!>b<!>) += 34
+        //repeat for b
+        (<!VARIABLE_EXPECTED!>b<!>) += 3
+    }
+
+    fun testArrays(a: Array<Int>, ab: Ab) {
+        a[3] = 4
+        a[4]++
+        a[6] += 43
+
+        ab.getArray()[54] = 23
+        ab.getArray()[54]++
+
+        (f@ a)[3] = 4
+
+        <!UNRESOLVED_REFERENCE!>this[54] = 34<!>
+    }
+}
+
+fun Array<Int>.checkThis() {
+    this[45] = 34
+    this[352]++
+    this[35] += 234
+}
+
+abstract class Ab {
+    abstract fun getArray() : Array<Int>
+}
diff --git a/compiler/testData/diagnostics/tests/LiteralAsResult.fir.kt b/compiler/testData/diagnostics/tests/LiteralAsResult.fir.kt
new file mode 100644
index 00000000000..434e19277b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/LiteralAsResult.fir.kt
@@ -0,0 +1,3 @@
+// Here we want just to check return type
+// Should be () -> Int
+fun foo() = { 42 }
diff --git a/compiler/testData/diagnostics/tests/LocalClassAndShortSubpackageNames.fir.kt b/compiler/testData/diagnostics/tests/LocalClassAndShortSubpackageNames.fir.kt
new file mode 100644
index 00000000000..cf97ae1f74a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/LocalClassAndShortSubpackageNames.fir.kt
@@ -0,0 +1,17 @@
+// FILE: A.kt
+package foo.bar
+
+class X
+
+// FILE: B.kt
+
+package foo
+
+fun f() {
+    class Local1 {
+        fun g() : bar.X? = null
+    }
+    class Local2 {
+        fun g() : foo.bar.X? = null
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/MultilineStringTemplates.fir.kt b/compiler/testData/diagnostics/tests/MultilineStringTemplates.fir.kt
new file mode 100644
index 00000000000..715007c246c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/MultilineStringTemplates.fir.kt
@@ -0,0 +1,43 @@
+fun box() : String {
+    val s = "abc"
+    val test1 = """$s"""
+    if (test1 != "abc") return "Fail 1: $test1"
+
+    val test2 = """${s}"""
+    if (test2 != "abc") return "Fail 2: $test2"
+
+    val test3 = """ "$s" """
+    if (test3 != " \"abc\" ") return "Fail 3: $test3"
+
+    val test4 = """ "${s}" """
+    if (test4 != " \"abc\" ") return "Fail 4: $test4"
+
+    val test5 =
+"""
+  ${s.length}
+"""
+    if (test5 != "\n  3\n") return "Fail 5: $test5"
+
+    val test6 = """\n"""
+    if (test6 != "\\n") return "Fail 6: $test6"
+
+    val test7 = """\${'$'}foo"""
+    if (test7 != "\\\$foo") return "Fail 7: $test7"
+
+    val test8 = """$ foo"""
+    if (test8 != "$ foo") return "Fail 8: $test8"
+
+    return "OK"
+}
+
+
+fun new() : String {
+  return """
+    sdfasdf
+    ${<!UNRESOLVED_REFERENCE!>a<!>}
+    ds"asdfas
+    $<!UNRESOLVED_REFERENCE!>b<!>
+    asgfaf
+  """
+
+}
diff --git a/compiler/testData/diagnostics/tests/MultipleBounds.fir.kt b/compiler/testData/diagnostics/tests/MultipleBounds.fir.kt
new file mode 100644
index 00000000000..966c8561ea9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/MultipleBounds.fir.kt
@@ -0,0 +1,69 @@
+package Jet87
+
+open class A() {
+  fun foo() : Int = 1
+}
+
+interface B {
+  fun bar() : Double = 1.0;
+}
+
+interface G<X> {
+    val <X> boo: Double  where X : A, X : B
+    val <A> bal: Double  where A : B
+    val <Y> bas: Double where Y : B, X : B
+}
+
+class C() : A(), B
+
+class D() {
+  companion object : A(), B {}
+}
+
+class Test1<T>()
+  where
+    T : A,
+    T : B,
+    B : T // error
+  {
+
+  fun test(t : T) {
+    <!OTHER_ERROR!>T<!>.<!UNRESOLVED_REFERENCE!>foo<!>()
+    <!OTHER_ERROR!>T<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+    t.foo()
+    t.bar()
+  }
+}
+
+fun test() {
+  Test1<B>()
+  Test1<A>()
+  Test1<C>()
+}
+
+class Foo() {}
+
+class Bar<T : Foo>
+
+class Buzz<T> where T : Bar<Int>, T : nioho
+
+class X<T : Foo>
+class Y<T> where T : Foo, T : Bar<Foo>
+
+fun <T> test2(t : T)
+  where
+    T : A,
+    T : B,
+    B : T
+{
+  <!OTHER_ERROR!>T<!>.<!UNRESOLVED_REFERENCE!>foo<!>()
+  <!OTHER_ERROR!>T<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+  t.foo()
+  t.bar()
+}
+
+val t1 = <!INAPPLICABLE_CANDIDATE!>test2<!><A>(A())
+val t2 = <!INAPPLICABLE_CANDIDATE!>test2<!><B>(C())
+val t3 = test2<C>(C())
+
+val <T, B : T> x : Int = 0
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/NamedFunctionTypeParameterInSupertype.fir.kt b/compiler/testData/diagnostics/tests/NamedFunctionTypeParameterInSupertype.fir.kt
new file mode 100644
index 00000000000..76b787ffc75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/NamedFunctionTypeParameterInSupertype.fir.kt
@@ -0,0 +1,9 @@
+abstract class A : Function1<Any, Unit>
+
+abstract class B : (Int)->Unit
+
+// Named parameter is prohibited because of possible inconsistency between
+// type declaration and actual override
+class C : (x: Int)->Unit {
+    override fun invoke(p1: Int): Unit {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Nullability.fir.kt b/compiler/testData/diagnostics/tests/Nullability.fir.kt
new file mode 100644
index 00000000000..c71b2e98286
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Nullability.fir.kt
@@ -0,0 +1,296 @@
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+fun test() {
+  val a : Int? = 0
+  if (a != null) {
+    a.plus(1)
+  }
+  else {
+    a?.plus(1)
+  }
+
+  val out : java.io.PrintStream? = null
+  val ins : java.io.InputStream? = null
+
+  out?.println()
+  ins?.read()
+
+  if (ins != null) {
+    ins.read()
+    out?.println()
+    if (out != null) {
+      ins.read();
+      out.println();
+    }
+  }
+
+  if (out != null && ins != null) {
+    ins.read();
+    out.println();
+  }
+
+  if (out == null) {
+    out?.println()
+  } else {
+    out.println()
+  }
+
+  if (out != null && ins != null || out != null) {
+    ins?.read();
+    ins.<!INAPPLICABLE_CANDIDATE!>read<!>();
+    out.println();
+  }
+
+  if (out == null || out.println(0) == Unit) {
+    out?.println(1)
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>(1)
+  }
+  else {
+    out.println(2)
+  }
+
+  if (out != null && out.println() == Unit) {
+    out.println();
+  }
+  else {
+    out?.println();
+  }
+
+  if (out == null || out.println() == Unit) {
+    out?.println();
+  }
+  else {
+    out.println();
+  }
+
+  if (1 == 2 || out != null && out.println(1) == Unit) {
+    out?.println(2);
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>(2);
+  }
+  else {
+    out?.println(3)
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>(3)
+  }
+
+  out?.println()
+  ins?.read()
+
+  if (ins != null) {
+    ins.read()
+    out?.println()
+    if (out != null) {
+      ins.read();
+      out.println();
+    }
+  }
+
+  if (out != null && ins != null) {
+    ins.read();
+    out.println();
+  }
+
+  if (out == null) {
+    out?.println()
+  } else {
+    out.println()
+  }
+
+  if (out != null && ins != null || out != null) {
+    ins?.read();
+    out.println();
+  }
+
+  if (out == null || out.println(0) == Unit) {
+    out?.println(1)
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>(1)
+  }
+  else {
+    out.println(2)
+  }
+
+  if (out != null && out.println() == Unit) {
+    out.println();
+  }
+  else {
+    out?.println();
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>();
+  }
+
+  if (out == null || out.println() == Unit) {
+    out?.println();
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>();
+  }
+  else {
+    out.println();
+  }
+
+  if (1 == 2 || out != null && out.println(1) == Unit) {
+    out?.println(2);
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>(2);
+  }
+  else {
+    out?.println(3)
+    out.<!INAPPLICABLE_CANDIDATE!>println<!>(3)
+  }
+
+  if (1 > 2) {
+    if (out == null) return;
+    out.println();
+  }
+  out?.println();
+
+  while (out != null) {
+    out.println();
+  }
+  out?.println();
+
+  val out2 : java.io.PrintStream? = null
+  
+  while (out2 == null) {
+    out2?.println();
+    out2.<!INAPPLICABLE_CANDIDATE!>println<!>();
+  }
+  out2.<!INAPPLICABLE_CANDIDATE!>println<!>()
+
+}
+
+
+fun f(out : String?) {
+  out?.get(0)
+  out.<!INAPPLICABLE_CANDIDATE!>get<!>(0)
+  if (out != null) else return;
+  out.get(0)
+}
+
+fun f1(out : String?) {
+  out?.get(0)
+  if (out != null) else {
+    1 + 2
+    return;
+  }
+  out.get(0)
+}
+
+fun f2(out : String?) {
+  out?.get(0)
+  if (out == null) {
+    1 + 2
+    return;
+  }
+  out.get(0)
+}
+
+fun f3(out : String?) {
+  out?.get(0)
+  if (out == null) {
+    1 + 2
+    return;
+  }
+  else {
+    1 + 2
+  }
+  out.get(0)
+}
+
+fun f4(s : String?) {
+  s?.get(0)
+  while (1 < 2 && s != null) {
+    s.get(0)
+  }
+  s?.get(0)
+  while (s == null || 1 < 2) {
+     s?.get(0)
+  }
+  s.get(0)
+}
+
+fun f5(s : String?) {
+  s?.get(0)
+  while (1 < 2 && s != null) {
+    s.get(0)
+  }
+  s?.get(0)
+  while (s == null || 1 < 2) {
+    if (1 > 2) break
+     s?.get(0)
+  }
+  s?.get(0);
+}
+
+fun f6(s : String?) {
+  s?.get(0)
+  do {
+    s?.get(0)
+    if (1 < 2) break;
+  } while (s == null)
+  s?.get(0)
+  do {
+    s?.get(0)
+  } while (s == null)
+  s.<!INAPPLICABLE_CANDIDATE!>get<!>(0)
+}
+
+fun f7(s : String?, t : String?) {
+  s?.get(0)
+  if (!(s == null)) {
+    s.get(0)
+  }
+  s?.get(0)
+  if (!(s != null)) {
+    s?.get(0)
+  }
+  else {
+    s.get(0)
+  }
+  s?.get(0)
+  if (!!(s != null)) {
+    s.get(0)
+  }
+  else {
+    s?.get(0)
+  }
+  s?.get(0)
+  t?.get(0)
+  if (!(s == null || t == null)) {
+    s.get(0)
+    t.get(0)
+  }
+  else {
+    s?.get(0)
+    t?.get(0)
+  }
+  s?.get(0)
+  t?.get(0)
+  if (!(s == null)) {
+    s.get(0)
+    t?.get(0)
+  }
+  else {
+    s?.get(0)
+    t?.get(0)
+  }
+}
+
+fun f8(b : String?, a : String) {
+  b?.get(0)
+  if (b == a) {
+    b.get(0);
+  }
+  b?.get(0)
+  if (a == b) {
+    b.get(0)
+  }
+  if (a != b) {
+    b?.get(0)
+  }
+  else {
+    b.<!INAPPLICABLE_CANDIDATE!>get<!>(0)
+  }
+}
+
+fun f9(a : Int?) : Int {
+  if (a != null)
+    return a
+  return 1
+}
diff --git a/compiler/testData/diagnostics/tests/NumberPrefixAndSuffix.fir.kt b/compiler/testData/diagnostics/tests/NumberPrefixAndSuffix.fir.kt
new file mode 100644
index 00000000000..7301b10cf92
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/NumberPrefixAndSuffix.fir.kt
@@ -0,0 +1,54 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -USELESS_CAST
+
+infix fun Any?.foo(a: Any) {}
+infix fun Any?.zoo(a: Any) {}
+infix fun Any?.Loo(a: Any) {}
+infix fun Any?.doo(a: Any) {}
+infix fun Any?.ddoo(a: Any) {}
+operator fun Any?.contains(a: Any): Boolean = true
+
+fun test(a: Any) {
+    1f<!UNRESOLVED_REFERENCE!>oo<!> a
+    1ffoo a
+    1doo a
+    1ddoo a
+    1contains a
+
+    1Lfoo a
+    1L<!UNRESOLVED_REFERENCE!>oo<!> a
+    1LLoo a
+
+    0b1foo a
+    0b1Lfoo a
+    0b1L<!UNRESOLVED_REFERENCE!>oo<!> a
+    0b1LLoo a
+
+    0xf<!UNRESOLVED_REFERENCE!>oo<!> a
+    0xff<!UNRESOLVED_REFERENCE!>oo<!> a
+    0xfLLoo a
+
+    1.0f<!UNRESOLVED_REFERENCE!>oo<!> a
+    1.0ffoo a
+    1.0doo a
+    1.0ddoo a
+
+    .0f<!UNRESOLVED_REFERENCE!>oo<!> a
+    .0ffoo a
+    .0doo a
+    .0ddoo a
+
+    1in a
+    1.0in a
+    1.0fin a
+    1.0<!UNRESOLVED_REFERENCE!>din<!> a
+    .0in a
+    .0fin a
+    .0<!UNRESOLVED_REFERENCE!>din<!> a
+
+    1is Any
+    1as Any
+    1as? Any
+
+    1!is Any
+    1!in a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ObjectWithConstructor.fir.kt b/compiler/testData/diagnostics/tests/ObjectWithConstructor.fir.kt
new file mode 100644
index 00000000000..7ee1f433ccc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ObjectWithConstructor.fir.kt
@@ -0,0 +1,24 @@
+object A1() {
+    constructor(x: Int = "", y: Int) : this() {
+        x + y
+    }
+}
+
+object A2 public constructor(private val prop: Int) {
+    constructor(x: Int = "", y: Int) : this(x * y) {
+        x + y
+    }
+}
+
+val x = object (val prop: Int) {
+    <!CONSTRUCTOR_IN_OBJECT, CONSTRUCTOR_IN_OBJECT!>constructor()<!> : <!UNRESOLVED_REFERENCE!>this<!>(1) {
+        val x = 1
+        x * x
+    }
+}
+
+class A3 {
+    companion object B(val prop: Int) {
+        public constructor() : this(2)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/OperatorChecks.fir.kt b/compiler/testData/diagnostics/tests/OperatorChecks.fir.kt
new file mode 100644
index 00000000000..ac4f09e9adc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/OperatorChecks.fir.kt
@@ -0,0 +1,219 @@
+// !DIAGNOSTICS: -EXTENSION_SHADOWED_BY_MEMBER
+
+import kotlin.reflect.KProperty
+
+interface Example {
+    operator fun plus(o: Example): Example
+    operator fun div(o: Example): Example
+    operator fun plus(o: Example, s: String = ""): Example
+    operator fun minus(vararg o: Example): Example
+    operator fun plus(): Example
+    operator fun minus(): Example
+
+    operator fun unaryPlus(): Example
+    operator fun unaryMinus(): Example
+
+    operator fun unaryPlus(s: String = ""): Example
+    operator fun unaryMinus(o: Example)
+
+    operator fun inc(): Example
+    operator fun dec(): Example?
+
+    operator fun plusAssign(n: Int)
+    operator fun minusAssign(n: Int): String
+    operator fun divAssign(n: Int, a: String = "")
+    operator fun modAssign(vararg n: Int)
+
+    operator fun compareTo(other: Example): Int
+
+    override operator fun equals(other: Any?): Boolean
+    operator fun equals(a: String): Boolean
+
+    operator fun contains(n: Int): Boolean
+    operator fun contains(n: Int, s: String = ""): Boolean
+
+    operator fun invoke()
+
+    operator fun get(n: Int)
+    operator fun get(n: Int, n2: Int)
+    operator fun get()
+
+    operator fun set(n: Int, v: Int)
+    operator fun set(n: Int, n2: Int, v: Int)
+    operator fun set(v: Int)
+
+    operator fun rangeTo(o: Int)
+    operator fun rangeTo(o: Int, o2: Int)
+    operator fun rangeTo(vararg o: String)
+
+    operator fun component1(): Int
+    operator fun component1(n: Int): Int
+    operator fun componentN(): Int
+
+    operator fun iterator(): String
+    operator fun iterator(n: Int): String
+
+    operator fun next(): String
+    operator fun next(n: Int): String
+
+    operator fun hasNext(): Boolean
+    operator fun hasNext(n: Int): String
+
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun i1(n: Int)<!>
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun i1(n: Int, n2: Int)<!>
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun i1(vararg n: Int)<!>
+}
+
+class OkDelegates {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = ""
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, s: String): String = ""
+    operator fun setValue(thisRef: Any?, prop: Any, n: Int) {}
+    operator fun setValue(thisRef: Any?, prop: Any?, s: String) {}
+}
+
+class DelegatesWithErrors {
+    operator fun getValue(thisRef: Any?, prop: String): String = ""
+    operator fun setValue(thisRef: Any?, prop: String, value: String) {}
+
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, vararg n: Int) {}
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, f: Float = 0.0f) {}
+
+    operator fun getValue(prop: KProperty<*>): String = ""
+    operator fun setValue(prop: KProperty<*>, value: String) {}
+}
+
+interface Example2 {
+    operator fun inc(s: String): Example
+    operator fun dec()
+    operator fun compareTo(vararg other: Example): Int
+    operator fun contains(vararg n: Int): Boolean
+    operator fun hasNext(): Int
+}
+
+interface Example3 {
+    operator fun compareTo(other: Example, s: String = ""): Int
+    operator fun contains(n: Int)
+}
+
+
+
+
+operator fun Example.plus(o: Any): Example {}
+operator fun Example.div(o: Example): Example {}
+operator fun Example.plus(o: Example, s: String = ""): Example {}
+operator fun Example.minus(vararg o: Example): Example {}
+operator fun Example.plus(): Example {}
+operator fun Example.minus(): Example {}
+
+operator fun Example.unaryPlus(): Example {}
+operator fun Example.unaryMinus(): Example {}
+
+operator fun Example.unaryPlus(s: String = ""): Example {}
+operator fun Example.unaryMinus(o: Example) {}
+
+operator fun Example.inc(): Example {}
+operator fun Example.dec(): Example? {}
+
+operator fun Example.plusAssign(n: Int) {}
+operator fun Example.minusAssign(n: Int): String {}
+operator fun Example.divAssign(n: Int, a: String = "") {}
+operator fun Example.modAssign(vararg n: Int) {}
+
+operator fun Example.compareTo(other: Example): Int {}
+
+operator fun Example.equals(a: String): Boolean {}
+
+operator fun Example.contains(n: Int): Boolean {}
+operator fun Example.contains(n: Int, s: String = ""): Boolean {}
+
+operator fun Example.invoke() {}
+
+operator fun Example.get(n: Int) {}
+operator fun Example.get(n: Int, n2: Int) {}
+operator fun Example.get() {}
+
+operator fun Example.set(n: Int, v: Int) {}
+operator fun Example.set(n: Int, n2: Int, v: Int) {}
+operator fun Example.set(v: Int) {}
+
+operator fun Example.rangeTo(o: Int) {}
+operator fun Example.rangeTo(o: Int, o2: Int) {}
+operator fun Example.rangeTo(vararg o: String) {}
+
+operator fun Example.component1(): Int {}
+operator fun Example.component1(n: Int): Int {}
+operator fun Example.componentN(): Int {}
+
+operator fun Example.iterator(): String {}
+operator fun Example.iterator(n: Int): String {}
+
+operator fun Example.next(): String {}
+operator fun Example.next(n: Int): String {}
+
+operator fun Example.hasNext(): Boolean {}
+operator fun Example.hasNext(n: Int): String {}
+
+infix fun Example.i1(n: Int) {}
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun Example.i1(n: Int, n2: Int) {}<!>
+infix fun Example.i1(vararg n: Int) {}
+
+
+
+
+
+operator fun plus(o: String): Example {}
+operator fun div(o: Example): Example {}
+operator fun plus(o: Example, s: String = ""): Example {}
+operator fun minus(vararg o: Example): Example {}
+
+operator fun unaryPlus(): Example {}
+operator fun unaryMinus(): Example {}
+
+operator fun unaryPlus(s: String = ""): Example {}
+operator fun unaryMinus(o: Example) {}
+
+operator fun inc(): Example {}
+operator fun dec(): Example? {}
+
+operator fun plusAssign(n: Int) {}
+operator fun minusAssign(n: Int): String {}
+operator fun divAssign(n: Int, a: String = "") {}
+operator fun modAssign(vararg n: Int) {}
+
+operator fun compareTo(other: Example): Int {}
+
+operator fun equals(a: String): Boolean {}
+
+operator fun contains(n: Int): Boolean {}
+operator fun contains(n: Int, s: String = ""): Boolean {}
+
+operator fun invoke() {}
+
+operator fun get(n: Int) {}
+operator fun get(n: Int, n2: Int) {}
+operator fun get() {}
+
+operator fun set(n: Int, v: Int) {}
+operator fun set(n: Int, n2: Int, v: Int) {}
+operator fun set(v: Int) {}
+
+operator fun rangeTo(o: Int) {}
+operator fun rangeTo(o: Int, o2: Int) {}
+operator fun rangeTo(vararg o: String) {}
+
+operator fun component1(): Int {}
+operator fun component1(n: Int): Int {}
+operator fun componentN(): Int {}
+
+operator fun iterator(): String {}
+operator fun iterator(n: Int): String {}
+
+operator fun next(): String {}
+operator fun next(n: Int): String {}
+
+operator fun hasNext(): Boolean {}
+operator fun hasNext(n: Int): String {}
+
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun i1(n: Int) {}<!>
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun i1(n: Int, n2: Int) {}<!>
+<!INAPPLICABLE_INFIX_MODIFIER!>infix fun i1(vararg n: Int) {}<!>
diff --git a/compiler/testData/diagnostics/tests/Operators.fir.kt b/compiler/testData/diagnostics/tests/Operators.fir.kt
new file mode 100644
index 00000000000..4e99d4993d7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Operators.fir.kt
@@ -0,0 +1,114 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Example {
+    public fun plus(o: Example) = o
+    public operator fun minus(o: Example) = o
+
+    public fun get(i: Int) = ""
+    public operator fun get(s: String) = ""
+
+    public fun set(i: Int, v: String) {}
+    public operator fun set(s: String, v: String) {}
+
+    public fun not() = false
+
+    public fun rangeTo(o: Example) = o
+    public fun contains(o: Example) = false
+    public fun compareTo(o: Example) = 0
+
+    public fun inc() = this
+    public fun dec() = this
+
+    public fun invoke() {}
+}
+
+class Example2 {
+    public operator fun not() = true
+
+    public fun plusAssign(o: Example2) {}
+    public operator fun minusAssign(o: Example2) {}
+
+    public operator fun rangeTo(o: Example2) = o
+    public operator fun contains(o: Example2) = false
+    public operator fun compareTo(o: Example2) = 0
+
+    public operator fun inc() = this
+    public operator fun dec() = this
+
+    public operator fun invoke() {}
+}
+
+fun test() {
+    var a = Example()
+    var b = Example()
+    var c = Example2()
+    var d = Example2()
+
+    Example() == Example()
+
+    a == b
+    c != d
+
+    Example() + Example()
+
+    a + b
+    a - b
+    a[1]
+    a["str"]
+
+    a[1] = "A"
+    a["str"] = "str"
+
+    a.plus(b)
+    a.minus(b)
+    a.get(1)
+    a.get("str")
+
+    c += d
+    c -= d
+
+    a..b
+    c..d
+
+    Example()..Example()
+    Example2()..Example2()
+
+    a < b
+    a >= b
+    c > d
+
+    a in b
+    c in d
+
+    a++
+    a--
+    c++
+    c--
+
+    !a
+    !c
+
+    a()
+    c()
+
+    Example()()
+    Example2()()
+}
+
+abstract class Base {
+    abstract operator fun plus(o: Base): Base
+    abstract fun minus(o: Base): Base
+}
+
+open class Anc : Base() {
+    override fun plus(o: Base) = o
+    override fun minus(o: Base) = o
+}
+
+class Anc2 : Anc()
+
+fun test2() {
+    Anc() + Anc()
+    Anc() - Anc()
+    Anc2() + Anc2()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/OperatorsWithWrongNames.fir.kt b/compiler/testData/diagnostics/tests/OperatorsWithWrongNames.fir.kt
new file mode 100644
index 00000000000..16440292185
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/OperatorsWithWrongNames.fir.kt
@@ -0,0 +1,11 @@
+class A {
+    operator fun A.minus(o: A) = o
+
+    operator fun A.add(o: A) = o
+    operator fun A.get(o: A) = o
+    operator fun A.invokee() {}
+}
+
+operator fun A.plus(o: A) = o
+operator fun A.component1() = 1
+operator fun A.componentN() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/OverrideFunctionWithParamDefaultValue.fir.kt b/compiler/testData/diagnostics/tests/OverrideFunctionWithParamDefaultValue.fir.kt
new file mode 100644
index 00000000000..df495e555ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/OverrideFunctionWithParamDefaultValue.fir.kt
@@ -0,0 +1,11 @@
+abstract class B() {
+    abstract fun foo2(arg: Int = 239) : Int
+}
+
+class C() : B() {
+    override fun foo2(arg: Int) : Int = arg
+}
+
+fun invokeIt() {
+    C().foo2()
+}
diff --git a/compiler/testData/diagnostics/tests/OverridenFunctionAndSpecifiedTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/OverridenFunctionAndSpecifiedTypeParameter.fir.kt
new file mode 100644
index 00000000000..95d4fdcc9c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/OverridenFunctionAndSpecifiedTypeParameter.fir.kt
@@ -0,0 +1,13 @@
+
+interface Aaa<T> {
+  fun zzz(value: T): Unit
+}
+
+class Bbb<T>() : Aaa<T> {
+    override fun zzz(value: T) { }
+}
+
+fun foo() {
+    var a = Bbb<Double>()
+    a.zzz(10.0)
+}
diff --git a/compiler/testData/diagnostics/tests/OverridenSetterVisibility.fir.kt b/compiler/testData/diagnostics/tests/OverridenSetterVisibility.fir.kt
new file mode 100644
index 00000000000..cbae506efc4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/OverridenSetterVisibility.fir.kt
@@ -0,0 +1,29 @@
+public interface ITest {
+    public var prop : Int
+        get() = 12
+        set(value) {}
+}
+
+abstract class ATest {
+    protected open var prop2 : Int
+        get() = 13
+        set(value) {}
+}
+
+class Test: ATest(), ITest {
+    override var prop : Int
+        get() = 12
+        private set(value) {}
+
+    override var prop2 : Int
+        get() = 14
+        internal set(value) {}
+}
+
+fun main() {
+    val test = Test()
+    test.prop = 12
+
+    val itest: ITest = test
+    itest.prop = 12 // No error here
+}
diff --git a/compiler/testData/diagnostics/tests/OverridingVarByVal.fir.kt b/compiler/testData/diagnostics/tests/OverridingVarByVal.fir.kt
new file mode 100644
index 00000000000..6ad543c6d65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/OverridingVarByVal.fir.kt
@@ -0,0 +1,15 @@
+open class Var() {
+  open var v : Int = 1
+}
+
+interface VarT {
+  var v : Int
+}
+
+class Val() : Var(), VarT {
+  override val v : Int = 1
+}
+
+class Var2() : Var() {
+  override var v : Int = 1
+}
diff --git a/compiler/testData/diagnostics/tests/PackageInExpressionPosition.fir.kt b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.fir.kt
new file mode 100644
index 00000000000..81208da3b4f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/PackageInExpressionPosition.fir.kt
@@ -0,0 +1,26 @@
+package foo
+
+class X {}
+
+val s = java
+val ss = System
+val sss = X
+val x = "${System}"
+val xs = java.lang
+val xss = java.<!UNRESOLVED_REFERENCE!>lang<!>.<!UNRESOLVED_REFERENCE!>System<!>
+val xsss = foo.X
+val xssss = foo
+val f = { System }
+
+fun main() {
+    java = null
+    System = null
+    System!!
+    java.lang.System = null
+    java.lang.System!!
+    System is Int
+    <!INAPPLICABLE_CANDIDATE!>System<!>()
+    (System)
+    foo@ System
+    null <!UNRESOLVED_REFERENCE!>in<!> System
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/PackageInTypePosition.fir.kt b/compiler/testData/diagnostics/tests/PackageInTypePosition.fir.kt
new file mode 100644
index 00000000000..4969f3b9ee1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/PackageInTypePosition.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: a.kt
+
+package foo
+
+// FILE: b.kt
+
+@foo fun bar(p: foo): foo = null!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/PackageQualified.fir.kt b/compiler/testData/diagnostics/tests/PackageQualified.fir.kt
new file mode 100644
index 00000000000..16faade22a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/PackageQualified.fir.kt
@@ -0,0 +1,71 @@
+// !WITH_NEW_INFERENCE
+// FILE: b.kt
+
+
+package foobar.a
+    import java.*
+
+    val a : java.util.List<Int>? = null
+    val a2 : util.List<Int>? = null
+    val a3 : LinkedList<Int>? = null
+
+// FILE: b.kt
+package foobar
+
+abstract class Foo<T>() {
+    abstract val x : T<Int>
+}
+
+// FILE: b.kt
+package foobar.a
+    import java.util.*
+
+    val b : List<Int>? = a
+    val b1 : util.List<Int>? = a
+
+// FILE: b.kt
+package foobar
+val x1 = <!UNRESOLVED_REFERENCE!>a<!>.<!UNRESOLVED_REFERENCE!>a<!>
+val x2 = foobar.a.a
+
+val y1 = foobar.a.b
+
+
+/////////////////////////////////////////////////////////////////////////
+
+fun <O> done(result : O) : Iteratee<Any?, O> = StrangeIterateeImpl<Any?, O>(result)
+
+abstract class Iteratee<in I, out O> {
+  abstract fun process(item : I) : Iteratee<I, O>
+  abstract val isDone : Boolean
+  abstract val result : O
+  abstract fun done() : O
+}
+
+class StrangeIterateeImpl<in I, out O>(val obj: O) : Iteratee<I, O>() {
+    override fun process(item: I): Iteratee<I, O> = StrangeIterateeImpl<I, O>(obj)
+    override val isDone = true
+    override val result = obj
+    override fun done() = obj
+}
+
+abstract class Sum() : Iteratee<Int, Int>() {
+  override fun process(item : Int) : Iteratee<Int, Int> {
+    return foobar.done<Int>(item);
+  }
+  abstract override val isDone : Boolean
+  abstract override val result : Int
+  abstract override fun done() : Int
+}
+
+abstract class Collection<E> : Iterable<E> {
+  fun <O> iterate(iteratee : Iteratee<E, O>) : O {
+      var current = iteratee
+      for (x in this) {
+        val it = current.process(x)
+        if (it.isDone) return it.result
+        current = it
+      }
+      return current.done()
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/PrimaryConstructors.fir.kt b/compiler/testData/diagnostics/tests/PrimaryConstructors.fir.kt
new file mode 100644
index 00000000000..d576493f416
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/PrimaryConstructors.fir.kt
@@ -0,0 +1,29 @@
+class X {
+  val x : Int
+}
+
+open class Y() {
+  val x : Int = 2
+}
+
+class Y1 {
+  val x : Int get() = 1
+}
+
+class Z : Y() {
+}
+
+//KT-650 Prohibit creating class without constructor.
+
+class MyIterable<T> : Iterable<T>
+{
+    override fun iterator(): Iterator<T>  = MyIterator()
+
+    inner class MyIterator : Iterator<T>
+    {
+        override fun hasNext(): Boolean = false
+        override fun next(): T {
+            throw UnsupportedOperationException()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/PrivateFromOuterPackage.fir.kt b/compiler/testData/diagnostics/tests/PrivateFromOuterPackage.fir.kt
new file mode 100644
index 00000000000..7c63a2ef936
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/PrivateFromOuterPackage.fir.kt
@@ -0,0 +1,25 @@
+// FILE: a.kt
+package outer
+
+private fun a() {}
+private class B
+
+// FILE: b.kt
+package outer.p1
+
+import outer.a
+
+fun use() {
+    <!INAPPLICABLE_CANDIDATE!>a<!>()
+    outer.<!INAPPLICABLE_CANDIDATE!>B<!>()
+}
+
+// FILE: c.kt
+package outer.p1.p2
+
+import outer.a
+
+fun use() {
+    <!INAPPLICABLE_CANDIDATE!>a<!>()
+    outer.<!INAPPLICABLE_CANDIDATE!>B<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/PrivateSetterForOverridden.fir.kt b/compiler/testData/diagnostics/tests/PrivateSetterForOverridden.fir.kt
new file mode 100644
index 00000000000..787940eac55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/PrivateSetterForOverridden.fir.kt
@@ -0,0 +1,70 @@
+// See KT-10325: private setters are allowed for overridden properties in final class
+
+interface A {
+    val a: Int
+
+    var b: Int
+}
+
+abstract class AA {
+    abstract val c: Int
+
+    abstract var d: Int
+}
+
+class B : A, AA() {
+    override var a: Int = 0
+        // Ok
+        private set
+
+    override var b: Int = 1
+        private set
+
+    override var c: Int = 2
+        // Ok
+        private set
+
+    override var d: Int = 3
+        private set
+}
+
+open class C : A, AA() {
+    override var a: Int = 0
+        // Errors here and below
+        private set
+
+    override var b: Int = 1
+        private set
+
+    override var c: Int = 2
+        private set
+
+    override var d: Int = 3
+        private set
+}
+
+abstract class D : A, AA() {
+    override var a: Int = 0
+        // Errors here and below
+        private set
+
+    override var b: Int = 1
+        private set
+
+    override var c: Int = 2
+        private set
+
+    override var d: Int = 3
+        private set
+}
+
+interface E : A {
+    override var a: Int
+        get() = 0
+        // Errors here and below
+        private set(arg) {}
+
+    override var b: Int
+        get() = 0
+        private set(arg) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ProcessingEmptyImport.fir.kt b/compiler/testData/diagnostics/tests/ProcessingEmptyImport.fir.kt
new file mode 100644
index 00000000000..35c39eae02b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ProcessingEmptyImport.fir.kt
@@ -0,0 +1,3 @@
+import<!SYNTAX!><!>
+
+fun firstFun() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ProjectionOnFunctionArgumentErrror.fir.kt b/compiler/testData/diagnostics/tests/ProjectionOnFunctionArgumentErrror.fir.kt
new file mode 100644
index 00000000000..43c935eb9b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ProjectionOnFunctionArgumentErrror.fir.kt
@@ -0,0 +1,4 @@
+fun test() {
+    fun <T> foo(){}
+    foo<in Int>()
+}
diff --git a/compiler/testData/diagnostics/tests/ProjectionsInSupertypes.fir.kt b/compiler/testData/diagnostics/tests/ProjectionsInSupertypes.fir.kt
new file mode 100644
index 00000000000..2e5805d7b18
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ProjectionsInSupertypes.fir.kt
@@ -0,0 +1,6 @@
+interface A<T> {}
+interface B<T> {}
+interface C<T> {}
+interface D<T> {}
+
+interface Test : A<in Int>, B<out Int>, C<*>???, D<Int> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Properties.fir.kt b/compiler/testData/diagnostics/tests/Properties.fir.kt
new file mode 100644
index 00000000000..ba5fcedde03
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Properties.fir.kt
@@ -0,0 +1,22 @@
+var x : Int = 1 + x
+   get() : Int = 1
+   set(value : Long) {
+      field = value.toInt()
+      field = 1.toLong()
+    }
+
+ val xx : Int = 1 + x
+   get() : Int = 1
+   set(value : Long) {}
+
+  val p : Int = 1
+    get() = 1
+
+class Test() {
+    var a : Int = 111
+    var b : Int = 222
+        get() = field
+        set(x) {a = x; field = x}
+
+   public val i = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/PropertyInitializers.fir.kt b/compiler/testData/diagnostics/tests/PropertyInitializers.fir.kt
new file mode 100644
index 00000000000..feecafe9145
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/PropertyInitializers.fir.kt
@@ -0,0 +1,9 @@
+class Foo(val a: Int, b: Int) {
+    val c = a + b
+
+    val d: Int
+        get() = a
+
+    val e: Int
+        get() = b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/QualifiedExpressions.fir.kt b/compiler/testData/diagnostics/tests/QualifiedExpressions.fir.kt
new file mode 100644
index 00000000000..d34cd8ec1cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/QualifiedExpressions.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+package qualified_expressions
+
+fun test(s: IntRange?) {
+   val a: Int = s?.start
+   val b: Int? = s?.start
+   val c: Int = s?.start ?: -11
+   val d: Int = s?.start ?: "empty"
+   val e: String = s?.start ?: "empty"
+   val f: Int = s?.endInclusive ?: b ?: 1
+   val g: Boolean? = e.startsWith("s")//?.length
+}
+
+fun String.startsWith(s: String): Boolean = true
diff --git a/compiler/testData/diagnostics/tests/RecursiveResolve.fir.kt b/compiler/testData/diagnostics/tests/RecursiveResolve.fir.kt
new file mode 100644
index 00000000000..39c0000bfff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/RecursiveResolve.fir.kt
@@ -0,0 +1,75 @@
+class Test(foo: Any?, bar: Any?) {
+    val foo = foo ?: this
+    private val bar = bar ?: this
+    private val bas = bas()
+    val bas2 = bas2()
+
+    private fun bas(): Int = null!!
+    private fun bas2(): Int = null!!
+
+    fun bar() = bar(1)
+    fun bar(i: Int) = 2
+    private fun bar2() = bar2(1)
+    private fun bar2(i: Int) = 2
+}
+
+// KT-6413 Typechecker recursive problem when class have non-invariant generic parameters
+class Test2<A, B, C>(foo: Any?, bar: Any?) {
+    val foo = foo ?: this
+    private val bar = bar ?: this
+    private val bas = bas()
+    val bas2 = bas2()
+
+    private fun bas(): Int = null!!
+    private fun bas2(): Int = null!!
+
+    fun bar() = bar(1)
+    fun bar(i: Int) = 2
+    private fun bar2() = bar2(1)
+    private fun bar2(i: Int) = 2
+}
+
+class Test3<in A, B, C>(foo: Any?, bar: Any?) {
+    val foo = foo ?: this
+    private val bar = bar ?: this
+    private val bas = bas()
+    val bas2 = bas2()
+
+    private fun bas(): Int = null!!
+    private fun bas2(): Int = null!!
+
+    fun bar() = bar(1)
+    fun bar(i: Int) = 2
+    private fun bar2() = bar2(1)
+    private fun bar2(i: Int) = 2
+}
+
+class Test4<A, out B, C>(foo: Any?, bar: Any?) {
+    val foo = foo ?: this
+    private val bar = bar ?: this
+    private val bas = bas()
+    val bas2 = bas2()
+
+    private fun bas(): Int = null!!
+    private fun bas2(): Int = null!!
+
+    fun bar() = bar(1)
+    fun bar(i: Int) = 2
+    private fun bar2() = bar2(1)
+    private fun bar2(i: Int) = 2
+}
+
+class Test5<A, out B, C>(foo: Any?, bar: Any?) {
+    val foo = foo ?: this
+    private val bar = bar ?: this
+    private val bas: Int = bas()
+    val bas2 = bas2()
+
+    private fun bas(): Int = null!!
+    private fun bas2(): Int = null!!
+
+    fun bar() = bar(1)
+    fun bar(i: Int) = 2
+    private fun bar2(): Int = bar2(1)
+    private fun bar2(i: Int) = 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/RecursiveTypeInference.fir.kt b/compiler/testData/diagnostics/tests/RecursiveTypeInference.fir.kt
new file mode 100644
index 00000000000..4c0c35b113a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/RecursiveTypeInference.fir.kt
@@ -0,0 +1,43 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+// FILE: f.kt
+package a
+    val foo = bar()
+
+    fun bar() = foo
+
+// FILE: f.kt
+package b
+    fun foo() = bar()
+
+    fun bar() = foo()
+
+// FILE: f.kt
+package c
+    fun bazz() = bar()
+
+    fun foo() = bazz()
+
+    fun bar() = foo()
+
+// FILE: f.kt
+
+    package ok.a
+        val foo = bar()
+
+        fun bar() : Int = foo
+
+// FILE: f.kt
+    package ok.b
+        fun foo() : Int = bar()
+
+        fun bar() = foo()
+
+// FILE: f.kt
+    package ok.c
+        fun bazz() = bar()
+
+        fun foo() : Int = bazz()
+
+        fun bar() = foo()
diff --git a/compiler/testData/diagnostics/tests/ReserveYield.fir.kt b/compiler/testData/diagnostics/tests/ReserveYield.fir.kt
new file mode 100644
index 00000000000..314f4435d9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ReserveYield.fir.kt
@@ -0,0 +1,71 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION -UNREACHABLE_CODE -UNUSED_VARIABLE
+
+// FILE: 1.kt
+package p1.yield
+
+import p1.yield.yield
+import p1.yield.foo
+
+val yield = 5
+fun foo(){}
+
+fun bar(yield: Int = 4) {}
+
+fun yield(yield: Int) {
+    "$yield"
+    "${yield}"
+
+    yield
+    val foo = yield + yield
+    val foo2 = yield
+
+    bar(yield = 5)
+
+    yield(4)
+    yield {}
+
+    class yield<T: yield<T>>
+
+    return@yield
+    return@yield Unit
+
+    val foo5: yield<*>
+}
+
+fun yield(i: (Int) -> Unit) {}
+
+// FILE: 2.kt
+
+package p2.yield
+
+import p2.yield.yield
+import p2.yield.foo
+
+val yield = 5
+fun foo(){}
+
+fun bar(yield: Int = 4) {}
+
+fun yield(yield: Int) {
+    "$`yield`"
+    "${`yield`}"
+
+    `yield`
+    val foo = `yield` + `yield`
+    val foo2 = `yield`
+
+    bar(`yield` = 5)
+
+    `yield`(4)
+    `yield` {}
+
+    class `yield`<T: `yield`<T>>
+
+    return@`yield`
+    return@`yield` Unit
+
+    val foo5: `yield`<*>
+}
+
+fun yield(i: (Int) -> Unit) {}
diff --git a/compiler/testData/diagnostics/tests/ReserveYield2.fir.kt b/compiler/testData/diagnostics/tests/ReserveYield2.fir.kt
new file mode 100644
index 00000000000..aab3b906def
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ReserveYield2.fir.kt
@@ -0,0 +1,54 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_EXPRESSION -UNREACHABLE_CODE -UNUSED_VARIABLE -WRONG_ANNOTATION_TARGET -UNUSED_LAMBDA_EXPRESSION
+
+// FILE: 1.kt
+
+annotation class yield
+
+fun bar(p: Int) {
+    yield@ p
+    `yield`@ p
+
+    @yield() p
+    @`yield`() p
+
+    for (yield in 1..5) {
+
+    }
+    { yield: Int -> }
+
+    val (yield) = listOf(4)
+
+}
+
+fun <T> listOf(vararg e: T): List<T> = null!!
+operator fun <T> List<T>.component1() = get(0)
+
+// FILE: 2.kt
+package p3
+
+enum class yield {
+    yield
+}
+
+fun f1(yield: Int, foo: Int = yield) {}
+
+fun f2(foo: yield) {}
+
+// FILE: 3.kt
+package p4
+
+typealias yield = Number
+
+fun <yield: Number> f1() {}
+fun <y: yield> f2() {}
+
+// FILE: 4.kt
+object X {
+    fun yield() {}
+
+    fun test3(yield: Int) {
+        X::yield
+
+        yield::toInt
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.fir.kt b/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.fir.kt
new file mode 100644
index 00000000000..8391182a406
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// Fixpoint generic in Java: Enum<T extends Enum<T>>
+fun test(a : java.lang.annotation.RetentionPolicy) {
+
+}
+
+fun test() {
+  java.util.Collections.emptyList()
+  val a : Collection<String>? = java.util.Collections.emptyList()
+}
+
+fun test(a : java.lang.Comparable<Int>) {
+
+}
+
+fun test(a : java.util.ArrayList<Int>) {
+
+}
+
+fun test(a : java.lang.Class<Int>) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ResolveToJava.fir.kt b/compiler/testData/diagnostics/tests/ResolveToJava.fir.kt
new file mode 100644
index 00000000000..223ad431198
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ResolveToJava.fir.kt
@@ -0,0 +1,58 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// JAVAC_SKIP
+// FULL_JDK
+
+// FILE: f.kt
+
+import java.*
+import java.util.*
+import utils.*
+
+import java.io.PrintStream
+import java.lang.Comparable as Com
+
+val l : MutableList<in Int> = ArrayList<Int>()
+
+fun test(l : java.util.List<Int>) {
+  val x : java.List
+  val y : java.util.List<Int>
+  val b : java.lang.Object
+  val z : java.utils.List<Int>
+
+  val f : java.io.File? = null
+
+  Collections.<!UNRESOLVED_REFERENCE!>emptyList<!>
+  Collections.<!UNRESOLVED_REFERENCE!>emptyList<!><Int>
+  Collections.emptyList<Int>()
+  Collections.emptyList()
+
+  checkSubtype<Set<Int>?>(Collections.singleton<Int>(1))
+  Collections.<!INAPPLICABLE_CANDIDATE!>singleton<!><Int>(1.0)
+
+  List<Int>
+
+
+  val o = "sdf" as Object
+
+  try {
+    // ...
+  }
+  catch(e: Exception) {
+    System.out.println(e.message)
+  }
+
+  PrintStream("sdf")
+
+  val c : Com<Int>? = null
+
+  checkSubtype<java.lang.Comparable<Int>?>(c)
+
+//  Collections.sort<Integer>(ArrayList<Integer>())
+  xxx.<!UNRESOLVED_REFERENCE!>Class<!>()
+}
+
+
+// FILE: f.kt
+package xxx
+  import java.lang.Class;
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Return.fir.kt b/compiler/testData/diagnostics/tests/Return.fir.kt
new file mode 100644
index 00000000000..747f383243e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Return.fir.kt
@@ -0,0 +1,17 @@
+package <!SYNTAX!>return<!>
+
+class A {
+    fun outer() {
+        fun inner() {
+            if (1 < 2)
+                return@inner
+            else
+            return@outer
+        }
+        if (1 < 2)
+            return@A
+        else if (2 < 3)
+            return@inner
+        return@outer
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/ReturnInFunctionWithoutBody.fir.kt b/compiler/testData/diagnostics/tests/ReturnInFunctionWithoutBody.fir.kt
new file mode 100644
index 00000000000..d2a51a83105
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ReturnInFunctionWithoutBody.fir.kt
@@ -0,0 +1,3 @@
+fun foo1(): () -> String = return { "some long expression "}
+fun foo2(): () -> String = return@label { "some long expression "}
+fun foo3(): () -> String = return<!SYNTAX!>@<!> { "some long expression "}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/SafeCallInvoke.fir.kt b/compiler/testData/diagnostics/tests/SafeCallInvoke.fir.kt
new file mode 100644
index 00000000000..b5366e9679c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SafeCallInvoke.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+class Rule(val apply:() -> Unit)
+
+fun bar() {}
+
+fun foo() {
+    val rule: Rule? = Rule { bar() }
+
+    // this compiles and works
+    val apply = rule?.apply
+    if (apply != null) apply()
+
+    // this compiles and works
+    rule?.apply?.invoke()
+
+    // this should be an error
+    rule?.apply()
+
+    // these both also ok (with smart cast / unnecessary safe call)
+    if (rule != null) {
+        rule.apply()
+        rule?.apply()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/SafeCallNonNullReceiver.fir.kt b/compiler/testData/diagnostics/tests/SafeCallNonNullReceiver.fir.kt
new file mode 100644
index 00000000000..4e4765234c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SafeCallNonNullReceiver.fir.kt
@@ -0,0 +1,6 @@
+// http://youtrack.jetbrains.net/issue/KT-418
+
+fun ff() {
+    val i: Int = 1
+    val a: Int = i?.plus(2)
+}
diff --git a/compiler/testData/diagnostics/tests/SafeCallNonNullReceiverReturnNull.fir.kt b/compiler/testData/diagnostics/tests/SafeCallNonNullReceiverReturnNull.fir.kt
new file mode 100644
index 00000000000..ccdd7aa33cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SafeCallNonNullReceiverReturnNull.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+fun Int.gg() = null
+
+fun ff() {
+    val a: Int = 1
+    val b: Int = a?.gg()
+}
diff --git a/compiler/testData/diagnostics/tests/SafeCallOnFakePackage.fir.kt b/compiler/testData/diagnostics/tests/SafeCallOnFakePackage.fir.kt
new file mode 100644
index 00000000000..9750c5ecc86
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SafeCallOnFakePackage.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Test.java
+public class Test {
+    public static final String FOO = "test";
+}
+
+// FILE: anotherTest.kt
+package foo
+
+val s: String = "test"
+
+// FILE: test.kt
+fun ff() {
+    val a = Test?.FOO
+    val b = foo?.s
+    System?.out.println(a + b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/SafeCallOnSuperReceiver.fir.kt b/compiler/testData/diagnostics/tests/SafeCallOnSuperReceiver.fir.kt
new file mode 100644
index 00000000000..0f1d94e9d7a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SafeCallOnSuperReceiver.fir.kt
@@ -0,0 +1,11 @@
+// http://youtrack.jetbrains.net/issue/KT-413
+
+open class A {
+    fun f() {}
+}
+
+class B : A() {
+    fun g() {
+        super?.f()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Serializable.fir.kt b/compiler/testData/diagnostics/tests/Serializable.fir.kt
new file mode 100644
index 00000000000..ee3ba199974
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Serializable.fir.kt
@@ -0,0 +1,55 @@
+fun use(s: java.io.Serializable) {
+
+}
+
+fun useList(s: List<java.io.Serializable>) {
+
+}
+
+fun testPrimitives(b: Byte, ss: Short, i: Int, l: Long, d: Double, s: String, f: Float, bool: Boolean) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(b)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(ss)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(i)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(l)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(s)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(f)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(d)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(bool)
+}
+
+class N
+class S: java.io.Serializable
+
+fun testArrays(ia: IntArray, ai: Array<Int>, an: Array<N>, a: Array<S>) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(ia)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(ai)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(an)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(a)
+}
+
+fun testLiterals() {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(1)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(1.0)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(11111111111111)
+    <!INAPPLICABLE_CANDIDATE!>use<!>("Asdsd")
+    <!INAPPLICABLE_CANDIDATE!>use<!>(true)
+}
+
+fun testNotSerializable(l: List<Int>) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(l)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(N())
+}
+
+enum class C {
+    E, E2
+}
+
+fun testEnums(a: Enum<*>) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(C.E)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(C.E2)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(a)
+}
+
+fun testLists(a: List<Int>) {
+    <!INAPPLICABLE_CANDIDATE!>useList<!>(a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/SetterVisibility.fir.kt b/compiler/testData/diagnostics/tests/SetterVisibility.fir.kt
new file mode 100644
index 00000000000..35e921407f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SetterVisibility.fir.kt
@@ -0,0 +1,25 @@
+class My {
+    var x: Int = 0
+        // Ok
+        private set
+    
+    private var y: Int = 1
+        // Error: better
+        public set
+
+    protected var z: Int = 2
+        // Ok
+        private set
+
+    protected var w: Int = 3
+        // Error: incompatible
+        internal set
+
+    internal var v: Int = 4
+        // Error: incompatible
+        protected set
+
+    internal var t: Int = 5
+        // Error: better
+        public set
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/ShiftFunctionTypes.fir.kt b/compiler/testData/diagnostics/tests/ShiftFunctionTypes.fir.kt
new file mode 100644
index 00000000000..cfc6fb59656
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ShiftFunctionTypes.fir.kt
@@ -0,0 +1,52 @@
+// FILE: f.kt
+class A {
+}
+
+// FILE: f.kt
+package n
+  class B
+// FILE: f.kt
+abstract class XXX() {
+    abstract val a : Int
+    abstract val a2 : n.B
+    abstract val a3 : (A)
+    abstract val a31 : (n.B)
+    abstract val a4 : A?
+    abstract val a5 : (A)?
+    abstract val a6 : (A?)
+    abstract val a7 : (A) -> n.B
+    abstract val a8 : (A, n.B) -> n.B
+
+//val a9 : (A, B)
+//val a10 : (B)? -> B
+
+    val a11 : ((Int) -> Int)? = null
+    val a12 : ((Int) -> (Int))? = null
+    abstract val a13 : Int.(Int) -> Int
+    abstract val a14 : n.B.(Int) -> Int
+    abstract val a15 : Int? .(Int) -> Int
+    abstract val a152 : (Int?).(Int) -> Int
+//    abstract val a151 : Int?.(Int) -> Int
+    abstract val a16 : (Int) -> (Int) -> Int
+    abstract val a17 : ((Int) -> Int).(Int) -> Int
+    abstract val a18 : (Int) -> ((Int) -> Int)
+    abstract val a19 : ((Int) -> Int) -> Int
+}
+
+abstract class YYY() {
+    abstract val a7 : (a : A) -> n.B
+    abstract val a8 : (a : A, b : n.B) -> n.B
+//val a9 : (A, B)
+//val a10 : (B)? -> B
+    val a11 : ((a : Int) -> Int)? = null
+    val a12 : ((a : Int) -> (Int))? = null
+    abstract val a13 : Int.(a : Int) -> Int
+    abstract val a14 : n.B.(a : Int) -> Int
+    abstract val a15 : Int? .(a : Int) -> Int
+    abstract val a152 : (Int?).(a : Int) -> Int
+//abstract val a151 : Int?.(a : Int) -> Int
+    abstract val a16 : (a : Int) -> (a : Int) -> Int
+    abstract val a17 : ((a : Int) -> Int).(a : Int) -> Int
+    abstract val a18 : (a : Int) -> ((a : Int) -> Int)
+    abstract val a19 : (b : (a : Int) -> Int) -> Int
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/SingleUnderscoreUnsupported.fir.kt b/compiler/testData/diagnostics/tests/SingleUnderscoreUnsupported.fir.kt
new file mode 100644
index 00000000000..691287f983b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SingleUnderscoreUnsupported.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: -SingleUnderscoreForParameterName
+
+data class A(val x: Int, val y: Int)
+
+fun foo(a: Array<A>) {
+    val (_, y) = A(1, 2)
+    y.hashCode()
+
+    val q1: (Int, String) -> Unit = {
+        _, s -> s.hashCode()
+    }
+    q1(1, "")
+
+    val q2: (Int, String) -> Unit = fun(_: Int, s: String) {
+        s.hashCode()
+    }
+    q2(1, "")
+
+    val q3: (A) -> Unit = {
+        (_, y) -> y.hashCode()
+    }
+    q3(A(2, 3))
+
+    for ((_, z) in a) {
+        z.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/StarsInFunctionCalls.fir.kt b/compiler/testData/diagnostics/tests/StarsInFunctionCalls.fir.kt
new file mode 100644
index 00000000000..bd8811ea0c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/StarsInFunctionCalls.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+
+fun <T> getT() {}
+fun <A, B> getTT() {}
+fun <A, B, C> getTTT(x : Any) {}
+fun foo(a : Any?) {}
+
+public fun main() {
+    getT<*>()
+    <!UNRESOLVED_REFERENCE!>ggetT<!><*>()
+    getTT<*, *>()
+    getTT<*, Int>()
+    getTT<Int, *>()
+    foo(getTTT<Int, *, Int>(1))
+}
diff --git a/compiler/testData/diagnostics/tests/StringPrefixAndSuffix.fir.kt b/compiler/testData/diagnostics/tests/StringPrefixAndSuffix.fir.kt
new file mode 100644
index 00000000000..f32edd2fe40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/StringPrefixAndSuffix.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+infix fun Any?.foo(a: Any) {}
+operator fun Any?.contains(a: Any): Boolean = true
+
+fun test(a: Any) {
+
+    a foo""
+    a foo"asd"
+    a foo"$a"
+    a foo"asd${a}sfsa"
+    a foo"""sdf"""
+    a foo'd'
+    a foo<!INFERENCE_ERROR!>''<!>
+
+    a foo""foo a
+    a foo"asd"foo a
+    a foo"$a"foo a
+    a foo"asd${a}sfsa"foo a
+    a foo"""sdf"""foo a
+    a foo'd'foo a
+    a foo<!INFERENCE_ERROR!>''<!>foo a
+
+    a in"foo"
+    a in"""foo"""
+    a in's'
+    a in<!INFERENCE_ERROR!>''<!>
+
+    a !in"foo"
+    a !in"""foo"""
+    a !in's'
+    a !in<!INFERENCE_ERROR!>''<!>
+
+    if("s"is Any) {}
+    if("s"is Any) {}
+    test("s"as Any)
+
+    a foo""<!SYNTAX!>1<!>
+    a foo""<!SYNTAX!>1.0<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/StringTemplates.fir.kt b/compiler/testData/diagnostics/tests/StringTemplates.fir.kt
new file mode 100644
index 00000000000..42ebed1181f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/StringTemplates.fir.kt
@@ -0,0 +1,22 @@
+fun demo() {
+  val abc = 1
+  val a = ""
+  val asd = 1
+  val bar = 5
+  fun map(f :  () -> Any?) : Int  = 1
+  fun buzz(f :  () -> Any?) : Int  = 1
+  val sdf = 1
+  val foo = 3;
+    "$abc"
+    "$"
+    "$.$.asdf$\t"
+    "asd\$"
+    "asd$a\x"
+    "asd$a$asd$ $<!UNRESOLVED_REFERENCE!>xxx<!>"
+    "fosdfasdo${1 + bar + 100}}sdsdfgdsfsdf"
+    "foo${bar + map {foo}}sdfsdf"
+    "foo${bar + map { "foo" }}sdfsdf"
+    "foo${bar + map {
+      "foo$sdf${ buzz{}}" }}sdfsdf"
+    "a\u \u0 \u00 \u000 \u0000 \u0AaA \u0AAz.length( ) + \u0022b"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/SupertypeListChecks.fir.kt b/compiler/testData/diagnostics/tests/SupertypeListChecks.fir.kt
new file mode 100644
index 00000000000..bbc92ce0967
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SupertypeListChecks.fir.kt
@@ -0,0 +1,49 @@
+// KT-286 Check supertype lists
+
+/*
+In a supertype list:
+ Same type should not be mentioned twice
+ Same type should not be indirectly mentioned with incoherent type arguments
+ Every interface's required dependencies should be satisfied
+ No final types should appear
+ Only one class is allowed
+*/
+
+class C1()
+
+open class OC1()
+
+open class C2 {}
+
+open class C3 {}
+
+interface T1 {}
+
+interface T2<T> {}
+
+interface Test() {
+}
+
+interface Test1 : C2() {}
+
+interface Test2 : C2 {}
+
+interface Test3 : C2, C3 {}
+
+interface Test4 : T1 {}
+
+interface Test5 : T1, T1 {}
+
+interface Test6 : C1 {}
+
+class CTest1() : OC1() {}
+
+class CTest2 : C2 {}
+
+class CTest3 : C2, C3 {}
+
+class CTest4 : T1 {}
+
+class CTest5 : T1, T1 {}
+
+class CTest6 : C1 {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/SyntaxErrorInTestHighlighting.fir.kt b/compiler/testData/diagnostics/tests/SyntaxErrorInTestHighlighting.fir.kt
new file mode 100644
index 00000000000..6698a262bcb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SyntaxErrorInTestHighlighting.fir.kt
@@ -0,0 +1,5 @@
+// dummy test of syntax error highlighting in tests
+
+fun get() {
+    1 + 2 <!SYNTAX!>2 3 4<!>
+}
diff --git a/compiler/testData/diagnostics/tests/SyntaxErrorInTestHighlightingEof.fir.kt b/compiler/testData/diagnostics/tests/SyntaxErrorInTestHighlightingEof.fir.kt
new file mode 100644
index 00000000000..7114933f970
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/SyntaxErrorInTestHighlightingEof.fir.kt
@@ -0,0 +1 @@
+fun f() {<!SYNTAX!><!>
diff --git a/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.fir.kt b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.fir.kt
new file mode 100644
index 00000000000..2866cc8751a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.fir.kt
@@ -0,0 +1,6 @@
+// JAVAC_EXPECTED_FILE
+interface MyTrait: Object {
+    override fun toString(): String
+    public override fun finalize()
+    public override fun wait()
+}
diff --git a/compiler/testData/diagnostics/tests/TraitWithConstructor.fir.kt b/compiler/testData/diagnostics/tests/TraitWithConstructor.fir.kt
new file mode 100644
index 00000000000..f4bc01edac2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/TraitWithConstructor.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -MISSING_CONSTRUCTOR_KEYWORD
+
+class C(val a: String) {}
+
+interface T1(val x: String) {}
+
+interface T2 constructor() {}
+
+interface T3 private constructor(a: Int) {}
+
+interface T4 {
+    constructor(a: Int) {
+        val b: Int = 1
+    }
+}
+
+interface T5 private () : T4 {}
+interface T6 private<!SYNTAX!><!> : T5 {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/TypeInference.fir.kt b/compiler/testData/diagnostics/tests/TypeInference.fir.kt
new file mode 100644
index 00000000000..b1f763b91b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/TypeInference.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+class C<T>() {
+  fun foo() : T {}
+}
+
+fun foo(c: C<Int>) {}
+fun <T> bar() : C<T> {}
+
+fun main() {
+  val a : C<Int> = C();
+  val x : C<in String> = C()
+  val y : C<out String> = C()
+  val z : C<*> = C()
+
+  val ba : C<Int> = bar();
+  val bx : C<in String> = bar()
+  val by : C<out String> = bar()
+  val bz : C<*> = bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/TypeMismatchOnOverrideWithSyntaxErrors.fir.kt b/compiler/testData/diagnostics/tests/TypeMismatchOnOverrideWithSyntaxErrors.fir.kt
new file mode 100644
index 00000000000..79f4f16d1bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/TypeMismatchOnOverrideWithSyntaxErrors.fir.kt
@@ -0,0 +1,9 @@
+abstract class A {
+    abstract var x: Int;
+    abstract fun foo() : Int;
+}
+
+abstract class C : A() {
+    override abstract var x: String =<!SYNTAX!><!> <!SYNTAX!>?<!>
+    override abstract fun foo(): String =<!SYNTAX!><!> <!SYNTAX!>?<!>
+}
diff --git a/compiler/testData/diagnostics/tests/Underscore.fir.kt b/compiler/testData/diagnostics/tests/Underscore.fir.kt
new file mode 100644
index 00000000000..1ab54eb4c44
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Underscore.fir.kt
@@ -0,0 +1,46 @@
+// !DIAGNOSTICS: -DEPRECATION -TOPLEVEL_TYPEALIASES_ONLY
+
+import kotlin.Deprecated as ___
+
+@___("") data class Pair(val x: Int, val y: Int)
+
+class _<________>
+val ______ = _<Int>()
+
+fun __(___: Int, y: _<Int>?): Int {
+    val (_, z) = Pair(___ - 1, 42)
+    val (x, __________) = Pair(___ - 1, 42)
+    val ____ = x
+    // in backquotes: allowed
+    val `_` = __________
+
+    val q = fun(_: Int, __: Int) {}
+    q(1, 2)
+
+    val _ = 56
+
+    fun localFun(_: String) = 1
+
+    __@ return if (y != null) __(____, y) else __(`_`, ______)
+}
+
+
+class A1(val _: String)
+class A2(_: String) {
+    class B {
+        typealias _ = CharSequence
+    }
+    val _: Int = 1
+
+    fun _() {}
+
+    fun foo(_: Double) {}
+}
+
+// one underscore parameters for named function are still prohibited
+fun oneUnderscore(_: Int) {}
+
+fun doIt(f: (Any?) -> Any?) = f(null)
+
+val something = doIt { __ -> __ }
+val something2 = doIt { _ -> 1 }
diff --git a/compiler/testData/diagnostics/tests/UnderscoreUsageInAnnotation.fir.kt b/compiler/testData/diagnostics/tests/UnderscoreUsageInAnnotation.fir.kt
new file mode 100644
index 00000000000..8259c0d577d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnderscoreUsageInAnnotation.fir.kt
@@ -0,0 +1,6 @@
+package test
+
+annotation class `__`(val value: String)
+
+@__("") class TestAnn
+@`__`("") class TestAnn2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/UnderscoreUsageInCall.fir.kt b/compiler/testData/diagnostics/tests/UnderscoreUsageInCall.fir.kt
new file mode 100644
index 00000000000..7c60cce7fc8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnderscoreUsageInCall.fir.kt
@@ -0,0 +1,42 @@
+// !DIAGNOSTICS: -DEPRECATION -TOPLEVEL_TYPEALIASES_ONLY
+
+fun test(`_`: Int) {
+    _ + 1
+    `_` + 1
+}
+
+fun `__`() {}
+
+fun testCall() {
+    __()
+    `__`()
+}
+
+val testCallableRef = ::__
+val testCallableRef2 = ::`__`
+
+
+object Host {
+    val `_` = 42
+    object `__` {
+        val bar = 4
+    }
+}
+
+val testQualified = Host._
+val testQualified2 = Host.`_`
+
+object `___` {
+    val test = 42
+}
+
+val testQualifier = ___.test
+val testQualifier2 = `___`.test
+val testQualifier3 = Host.__.bar
+val testQualifier4 = Host.`__`.bar
+
+fun testCallableRefLHSValue(`_`: Any) = _::toString
+fun testCallableRefLHSValue2(`_`: Any) = `_`::toString
+
+val testCallableRefLHSObject = ___::toString
+val testCallableRefLHSObject2 = `___`::toString
diff --git a/compiler/testData/diagnostics/tests/UnderscoreUsageInCallableRefTypeLHS.fir.kt b/compiler/testData/diagnostics/tests/UnderscoreUsageInCallableRefTypeLHS.fir.kt
new file mode 100644
index 00000000000..e97cd0f103f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnderscoreUsageInCallableRefTypeLHS.fir.kt
@@ -0,0 +1,11 @@
+class `___` {
+    class `____`
+}
+
+val testCallableRefLHSType = ___::toString
+val testCallableRefLHSType2 = `___`::toString
+
+val testClassLiteralLHSType = ___::class
+val testClassLiteralLHSType2 = `___`::class
+
+val tesLHSTypeFQN = `___`.____::class
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/UnderscoreUsageInType.fir.kt b/compiler/testData/diagnostics/tests/UnderscoreUsageInType.fir.kt
new file mode 100644
index 00000000000..181bc7a41cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnderscoreUsageInType.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -DEPRECATION -TOPLEVEL_TYPEALIASES_ONLY
+
+class `_`<`__`> {
+    fun testTypeArgument(x: List<__>) = x
+    fun testTypeArgument2(x: List<`__`>) = x
+}
+
+fun _<Any>.testTypeConstructor() {}
+fun `_`<Any>.testTypeConstructor2() {}
+
+val testConstructor = _<Any>()
+val testConstructor2 = `_`<Any>()
diff --git a/compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.fir.kt b/compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.fir.kt
new file mode 100644
index 00000000000..84c1dc55f57
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnderscoreUsageInVariableAsFunctionCall.fir.kt
@@ -0,0 +1,6 @@
+object Host {
+    val `____` = { -> }
+    fun testFunTypeVal() {
+        ____()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/UnitByDefaultForFunctionTypes.fir.kt b/compiler/testData/diagnostics/tests/UnitByDefaultForFunctionTypes.fir.kt
new file mode 100644
index 00000000000..bf866f26c3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnitByDefaultForFunctionTypes.fir.kt
@@ -0,0 +1,3 @@
+fun foo(f : () -> Unit) {
+    val x : Unit = f()
+}
diff --git a/compiler/testData/diagnostics/tests/UnitValue.fir.kt b/compiler/testData/diagnostics/tests/UnitValue.fir.kt
new file mode 100644
index 00000000000..b4d92bc704a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnitValue.fir.kt
@@ -0,0 +1,5 @@
+// !CHECK_TYPE
+
+fun test() {
+  return checkSubtype<Unit>(Unit)
+}
diff --git a/compiler/testData/diagnostics/tests/Unresolved.fir.kt b/compiler/testData/diagnostics/tests/Unresolved.fir.kt
new file mode 100644
index 00000000000..d4133613353
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Unresolved.fir.kt
@@ -0,0 +1,32 @@
+package unresolved
+
+class Pair<A, B>(val a: A, val b: B)
+
+fun testGenericArgumentsCount() {
+    val p1: Pair<Int> = Pair(2, 2)
+    val p2: Pair = Pair(2, 2)
+}
+
+fun testUnresolved() {
+    if (<!UNRESOLVED_REFERENCE!>a<!> is String) {
+        val s = <!UNRESOLVED_REFERENCE!>a<!>
+    }
+    <!UNRESOLVED_REFERENCE!>foo<!>(<!UNRESOLVED_REFERENCE!>a<!>)
+    val s = "s"
+    <!UNRESOLVED_REFERENCE!>foo<!>(s)
+    foo1(<!UNRESOLVED_REFERENCE!>i<!>)
+    s.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+    when(<!UNRESOLVED_REFERENCE!>a<!>) {
+        is Int -> <!UNRESOLVED_REFERENCE!>a<!>
+        is String -> <!UNRESOLVED_REFERENCE!>a<!>
+    }
+
+    <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (j in <!UNRESOLVED_REFERENCE!>collection<!>) {
+       var i: Int = j
+       i += 1
+       foo1(j)
+    }<!>
+}
+
+fun foo1(i: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/UnusedInDestructuring.fir.kt b/compiler/testData/diagnostics/tests/UnusedInDestructuring.fir.kt
new file mode 100644
index 00000000000..ddf1ff5a0fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnusedInDestructuring.fir.kt
@@ -0,0 +1,9 @@
+data class D(val x: Int, val y: Int, val z: Int)
+fun foo(): Int {
+    val (x, y, z) = D(1, 2, 3)
+    return y + z // x is not used, but we cannot do anything with it
+}
+fun bar(): Int {
+    val (x, y, z) = D(1, 2, 3)
+    return y + x // z is not used
+}
diff --git a/compiler/testData/diagnostics/tests/UnusedParameters.fir.kt b/compiler/testData/diagnostics/tests/UnusedParameters.fir.kt
new file mode 100644
index 00000000000..17eed4370af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnusedParameters.fir.kt
@@ -0,0 +1,43 @@
+import kotlin.reflect.KProperty
+
+class C(a: Int, b: Int, c: Int, d: Int, e: Int = d, val f: String) {
+    init {
+        a + a
+    }
+
+    val g = b
+
+    init {
+        c + c
+    }
+}
+
+fun f(a: Int, b: Int, c: Int = b) {
+    a + a
+}
+
+fun Any.getValue(thisRef: Any?, prop: KProperty<*>): String = ":)"
+fun Any.setValue(thisRef: Any?, prop: KProperty<*>, value: String) {
+}
+
+fun Any.provideDelegate(thisRef: Any?, prop: KProperty<*>) {
+}
+
+operator fun Int.getValue(thisRef: Any?, prop: KProperty<*>): String = ":)"
+
+operator fun Int.setValue(thisRef: Any?, prop: KProperty<*>, value: String) {
+}
+
+operator fun Int.provideDelegate(thisRef: Any?, prop: KProperty<*>) {
+}
+
+
+fun get(p: Any) {
+}
+
+fun set(p: Any) {
+}
+
+fun foo(s: String) {
+    s.<!UNRESOLVED_REFERENCE!>xxx<!> = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/UnusedParametersVersion10.fir.kt b/compiler/testData/diagnostics/tests/UnusedParametersVersion10.fir.kt
new file mode 100644
index 00000000000..b3c56ab9bd4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnusedParametersVersion10.fir.kt
@@ -0,0 +1,3 @@
+// !LANGUAGE: -SingleUnderscoreForParameterName
+
+val x = 1.let { arg -> }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/UnusedVariables.fir.kt b/compiler/testData/diagnostics/tests/UnusedVariables.fir.kt
new file mode 100644
index 00000000000..70f2c6d91cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/UnusedVariables.fir.kt
@@ -0,0 +1,133 @@
+package unused_variables
+
+fun testSimpleCases() {
+    var i = 2
+    i = 34
+    i = 34
+    doSmth(i)
+    i = 5
+
+    var j = 2
+    j = j++
+    j = j--
+}
+
+class IncDec() {
+  operator fun inc() : IncDec = this
+  operator fun dec() : IncDec = this
+}
+
+class MyTest() {
+    fun testIncDec() {
+      var x = IncDec()
+      x++
+      ++x
+      x--
+      --x
+      x = x++
+      x = x--
+      x = ++x
+      x = --x
+    }
+
+    var a: String = "s"
+        set(v: String) {
+            var i: Int = 23
+            doSmth(i)
+            i = 34
+            field = v
+        }
+
+    init {
+        a = "rr"
+    }
+
+    fun testSimple() {
+        a = "rro"
+
+        var i = 1;
+        i = 34;
+        i = 456;
+    }
+
+    fun testWhile() {
+        var a : Any? = true
+        var b : Any? = 34
+        while (a is Any) {
+            a = null
+        }
+        while (b != null) {
+            a = null
+        }
+    }
+
+    fun testIf() {
+        var a : Any
+        if (1 < 2) {
+            a = 23
+        }
+        else {
+            a = "ss"
+            doSmth(a)
+        }
+        doSmth(a)
+
+        if (1 < 2) {
+            a = 23
+        }
+        else {
+            a = "ss"
+        }
+    }
+
+    fun testFor() {
+        for (i in 1..10) {
+            doSmth(i)
+        }
+    }
+
+    fun doSmth(s: String) {}
+    fun doSmth(a: Any) {}
+}
+
+fun testInnerFunctions() {
+    var y = 1
+    fun foo() {
+        y = 1
+    }
+    var z = 1
+    fun bar() {
+        doSmth(z)
+    }
+}
+
+fun testFunctionLiterals() {
+    var x = 1
+    var fl = {
+        x
+    }
+    var y = 2
+    var fl1 = {
+        doSmth(y)
+    }
+}
+
+interface Trait {
+    fun foo()
+}
+
+fun testObject() : Trait {
+    val x = 24
+    val o = object : Trait {
+        val y : Int   //in this case y should not be marked as unused
+           get() = 55
+
+        override fun foo() {
+            doSmth(x)
+        }
+    }
+
+    return o
+}
+
+fun doSmth(i : Int) {}
diff --git a/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.fir.kt b/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.fir.kt
new file mode 100644
index 00000000000..6331a7778ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.fir.kt
@@ -0,0 +1,9 @@
+// JAVAC_EXPECTED_FILE
+class Foo1() : java.util.ArrayList<Int>()
+
+open class Bar() {
+    fun v() : Int  = 1
+    val v : Int = 1
+}
+
+class Barr() : Bar() {}
diff --git a/compiler/testData/diagnostics/tests/VarargTypes.fir.kt b/compiler/testData/diagnostics/tests/VarargTypes.fir.kt
new file mode 100644
index 00000000000..66e2f692ab9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/VarargTypes.fir.kt
@@ -0,0 +1,26 @@
+// KT-389 Wrong type inference for varargs etc.
+
+import java.util.*
+
+fun foob(vararg a : Byte) : ByteArray = a
+fun fooc(vararg a : Char) : CharArray = a
+fun foos(vararg a : Short) : ShortArray = a
+fun fooi(vararg a : Int) : IntArray = a
+fun fool(vararg a : Long) : LongArray = a
+fun food(vararg a : Double) : DoubleArray = a
+fun foof(vararg a : Float) : FloatArray = a
+fun foob(vararg a : Boolean) : BooleanArray = a
+fun foos(vararg a : String) : Array<out String> = a
+
+fun test() {
+    Arrays.asList(1, 2, 3)
+    Arrays.asList<Int>(1, 2, 3)
+
+    foob(1, 2, 3)
+    foos(1, 2, 3)
+    fooc('1', '2', '3')
+    fooi(1, 2, 3)
+    fool(1, 2, 3)
+    food(1.0, 2.0, 3.0)
+    foof(1.0.toFloat(), 2.0.toFloat(), 3.0.toFloat())
+}
diff --git a/compiler/testData/diagnostics/tests/Varargs.fir.kt b/compiler/testData/diagnostics/tests/Varargs.fir.kt
new file mode 100644
index 00000000000..a37f503f461
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Varargs.fir.kt
@@ -0,0 +1,17 @@
+fun v(x : Int, y : String, vararg f : Long) {}
+fun v1(vararg f :  (Int) -> Unit) {}
+
+fun test() {
+    v(1, "")
+    v(1, "", 1)
+    v(1, "", 1, 1, 1)
+    v(1, "", 1, 1, 1)
+
+    v1()
+    v1({})
+    v1({}, {})
+    <!INAPPLICABLE_CANDIDATE!>v1<!>({}, 1, {})
+    v1({}, {}, {it})
+    v1({}) {}
+    v1 {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/Variance.fir.kt b/compiler/testData/diagnostics/tests/Variance.fir.kt
new file mode 100644
index 00000000000..72753b660a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/Variance.fir.kt
@@ -0,0 +1,41 @@
+// !WITH_NEW_INFERENCE
+package variance
+
+abstract class Consumer<in T> {}
+
+abstract class Producer<out T> {}
+
+abstract class Usual<T> {}
+
+fun foo(c: Consumer<Int>, p: Producer<Int>, u: Usual<Int>) {
+    val c1: Consumer<Any> = c
+    val c2: Consumer<Int> = c1
+
+    val p1: Producer<Any> = p
+    val p2: Producer<Int> = p1
+
+    val u1: Usual<Any> = u
+    val u2: Usual<Int> = u1
+}
+
+//Arrays copy example
+class Array<T>(val length : Int, val t : T) {
+    fun get(index : Int) : T { return t }
+    fun set(index : Int, value : T) { /* ... */ }
+}
+
+fun copy1(from : Array<Any>, to : Array<Any>) {}
+
+fun copy2(from : Array<out Any>, to : Array<in Any>) {}
+
+fun <T> copy3(from : Array<out T>, to : Array<in T>) {}
+
+fun copy4(from : Array<out Number>, to : Array<in Int>) {}
+
+fun f(ints: Array<Int>, any: Array<Any>, numbers: Array<Number>) {
+    <!INAPPLICABLE_CANDIDATE!>copy1<!>(ints, any)
+    copy2(ints, any) //ok
+    <!INAPPLICABLE_CANDIDATE!>copy2<!>(ints, numbers)
+    copy3<Int>(ints, numbers)
+    copy4(ints, numbers) //ok
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AmbigiousAnnotationConstructor.fir.kt b/compiler/testData/diagnostics/tests/annotations/AmbigiousAnnotationConstructor.fir.kt
new file mode 100644
index 00000000000..e2fb989be02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AmbigiousAnnotationConstructor.fir.kt
@@ -0,0 +1,6 @@
+// !WITH_NEW_INFERENCE
+import java.util.ArrayList
+
+@ArrayList<Int>(1, 1) fun b() {}
+@Xoo(<!UNRESOLVED_REFERENCE!>x<!>) fun c() {}
+@java.lang.Deprecated(<!UNRESOLVED_REFERENCE!>x<!>) fun a() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotatedConstructor.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotatedConstructor.fir.kt
new file mode 100644
index 00000000000..32e92a33f72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotatedConstructor.fir.kt
@@ -0,0 +1,2 @@
+annotation class ann
+class Annotated(@ann val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotatedConstructorParams.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotatedConstructorParams.fir.kt
new file mode 100644
index 00000000000..f53a25d9ee4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotatedConstructorParams.fir.kt
@@ -0,0 +1,15 @@
+package a
+
+import java.lang.Deprecated as deprecated
+import java.lang.SuppressWarnings as suppresswarnings
+
+
+@deprecated @suppresswarnings val s: String = "";
+
+@deprecated @suppresswarnings fun main() {
+    System.out.println("Hello, world!")
+}
+
+class Test(@deprecated val s: String,
+           @suppresswarnings val x : Int) {}
+
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotatedLocalObjectFun.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotatedLocalObjectFun.fir.kt
new file mode 100644
index 00000000000..bdb7dca248a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotatedLocalObjectFun.fir.kt
@@ -0,0 +1,8 @@
+annotation class My
+
+fun foo() {
+    val s = object {
+        @My fun bar() {}
+    }
+    s.bar()
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotatedLocalObjectProperty.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotatedLocalObjectProperty.fir.kt
new file mode 100644
index 00000000000..1f95a8ea8ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotatedLocalObjectProperty.fir.kt
@@ -0,0 +1,8 @@
+annotation class My
+
+fun foo(): Int {
+    val s = object {
+        @My val bar: Int = 0
+    }
+    return s.bar
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotatedLoop.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotatedLoop.fir.kt
new file mode 100644
index 00000000000..1d30d760f42
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotatedLoop.fir.kt
@@ -0,0 +1,8 @@
+@Target(AnnotationTarget.TYPE)
+annotation class My
+
+fun foo() {
+    for (i: @My Int in 0..41) {
+        if (i == 13) return
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotatedResultType.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotatedResultType.fir.kt
new file mode 100644
index 00000000000..af41d3d5944
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotatedResultType.fir.kt
@@ -0,0 +1,5 @@
+// Result type can be annotated
+@Target(AnnotationTarget.TYPE)
+annotation class My(val x: Int)
+
+fun foo(): @My(42) Int = 24
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotatedTryCatch.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotatedTryCatch.fir.kt
new file mode 100644
index 00000000000..e98b5122708
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotatedTryCatch.fir.kt
@@ -0,0 +1,9 @@
+annotation class My
+
+fun foo(arg: Int): Int {
+    try {
+        return 1 / (arg - arg)
+    } catch (e: @My Exception) {
+        return -1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationAsDefaultParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationAsDefaultParameter.fir.kt
new file mode 100644
index 00000000000..a1ef09e0da3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationAsDefaultParameter.fir.kt
@@ -0,0 +1,5 @@
+annotation class Base(val x: Int)
+
+annotation class UseBase(val b: Base = Base(0))
+
+@UseBase class My
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationForClassTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationForClassTypeParameter.fir.kt
new file mode 100644
index 00000000000..dc3b6defedf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationForClassTypeParameter.fir.kt
@@ -0,0 +1,10 @@
+annotation class A1
+annotation class A2(val some: Int = 12)
+
+class TopLevelClass<@A1 @A2(3) @A2 @A1(12) @A2("Test") T> {
+    class InnerClass<@A1 @A2(3) @A2 @A1(12) @A2("Test") T> {
+        fun test() {
+            class InFun<@A1 @A2(3) @A2 @A1(12) @A2("Test") T>
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationForFunctionTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationForFunctionTypeParameter.fir.kt
new file mode 100644
index 00000000000..45b6124e8c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationForFunctionTypeParameter.fir.kt
@@ -0,0 +1,12 @@
+annotation class A1
+annotation class A2(val some: Int = 12)
+
+fun <@A1 @A2(3) @A2 @A1(12) @A2("Test")  T> topFun() = 12
+
+class SomeClass {
+    fun <@A1 @A2(3) @A2 @A1(12) @A2("Test") T> method() = 12
+
+    fun foo() {
+        fun <@A1 @A2(3) @A2 @A1(12) @A2("Test")  T> innerFun() = 12
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationForObject.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationForObject.fir.kt
new file mode 100644
index 00000000000..d775c840fa8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationForObject.fir.kt
@@ -0,0 +1,3 @@
+// Check that there won't be "Rewrite at slice ANNOTATION key" exception - EA-36935
+@someErrorAnnotation object Test {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationIdentifier.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationIdentifier.fir.kt
new file mode 100644
index 00000000000..57427f7f9ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationIdentifier.fir.kt
@@ -0,0 +1,19 @@
+// FILE: a.kt
+
+annotation class annotation
+
+// FILE: test/b.kt
+
+package test
+
+@test.annotation class annotation
+
+// FILE: other/c.kt
+
+package other
+
+annotation class My
+
+@test.annotation class Your
+
+@My class Our
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationOnObject.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationOnObject.fir.kt
new file mode 100644
index 00000000000..bfc2133b520
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationOnObject.fir.kt
@@ -0,0 +1,6 @@
+package test
+
+annotation class A(val a: Int = 12, val b: String = "Test", val c: String)
+
+@A(a = 12, c = "Hello")
+object SomeObject
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationsForClasses.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationsForClasses.fir.kt
new file mode 100644
index 00000000000..b33157d0892
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationsForClasses.fir.kt
@@ -0,0 +1 @@
+annotation @java.lang.Deprecated class my
diff --git a/compiler/testData/diagnostics/tests/annotations/AnnotationsForPropertyTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/AnnotationsForPropertyTypeParameter.fir.kt
new file mode 100644
index 00000000000..f5f40eedd69
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/AnnotationsForPropertyTypeParameter.fir.kt
@@ -0,0 +1,12 @@
+annotation class A1
+annotation class A2(val some: Int = 12)
+
+val <@A1 @A2(3) @A2 @A1(12) @A2("Test")  T> T.topProp: Int get() = 12
+
+class SomeClass {
+    val <@A1 @A2(3) @A2 @A1(12) @A2("Test") T> T.field: Int get() = 12
+
+    fun foo() {
+        val <@A1 @A2(3) @A2 @A1(12) @A2("Test") T> localVal = 12
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/BasicAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/BasicAnnotations.fir.kt
new file mode 100644
index 00000000000..96404567511
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/BasicAnnotations.fir.kt
@@ -0,0 +1,10 @@
+annotation class my
+annotation class my1(val i : Int)
+annotation class my2(val i : Int = 0)
+
+@my fun foo() {}
+@my1 fun foo2() {}
+@my1(2) fun foo3() {}
+@my2() fun foo4() {}
+@my2 fun foo41() {}
+@my2(2) fun foo42() {}
diff --git a/compiler/testData/diagnostics/tests/annotations/ConstructorCall.fir.kt b/compiler/testData/diagnostics/tests/annotations/ConstructorCall.fir.kt
new file mode 100644
index 00000000000..21188f702fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/ConstructorCall.fir.kt
@@ -0,0 +1,35 @@
+annotation class Ann
+annotation class Ann1(val a: Int)
+annotation class Ann2(val a: Ann1)
+
+annotation class Ann3(val a: Ann1 = Ann1(1))
+
+annotation class Ann4(val value: String)
+
+@Ann2(Ann1(1)) val a = 1
+
+@Ann2(a = Ann1(1)) val c = 2
+
+@Ann4("a") class MyClass
+
+fun foo() {
+    Ann()
+    val a = Ann()
+
+    <!INAPPLICABLE_CANDIDATE!>Ann1<!>()
+    Ann1(1)
+    bar(Ann())
+    bar(a = Ann())
+
+    val ann = javaClass<MyClass>().getAnnotation(javaClass<Ann4>())
+    ann!!.value()
+}
+
+fun bar(a: Ann = Ann()) {
+    if (a is Ann) {}
+}
+
+operator fun String.invoke() {}
+
+// from stdlib
+fun <T> javaClass() : Class<T> = null as Class<T>
diff --git a/compiler/testData/diagnostics/tests/annotations/DanglingMixed.fir.kt b/compiler/testData/diagnostics/tests/annotations/DanglingMixed.fir.kt
new file mode 100644
index 00000000000..5e619361ce3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/DanglingMixed.fir.kt
@@ -0,0 +1,22 @@
+annotation class Ann
+annotation class Ann2
+
+class C {
+    fun foo() {
+        class Local {
+            @Ann0
+            @Ann @Ann3
+            @Ann2(1)
+            @Ann4<!SYNTAX!><!>
+        }
+    }
+    @Ann0
+    @Ann @Ann3
+    @Ann2(1)
+    @Ann4<!SYNTAX!><!>
+}
+
+@Ann0
+@Ann @Ann3
+@Ann2(1)
+@Ann4<!SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/DanglingNoBrackets.fir.kt b/compiler/testData/diagnostics/tests/annotations/DanglingNoBrackets.fir.kt
new file mode 100644
index 00000000000..fe2e95895bd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/DanglingNoBrackets.fir.kt
@@ -0,0 +1,13 @@
+annotation class Ann
+
+class C {
+    fun foo() {
+        class Local {
+            @Ann<!SYNTAX!><!>
+        }
+    }
+
+    @Ann<!SYNTAX!><!>
+}
+
+@Ann<!SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/DanglingWithBrackets.fir.kt b/compiler/testData/diagnostics/tests/annotations/DanglingWithBrackets.fir.kt
new file mode 100644
index 00000000000..8a0f5e78d5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/DanglingWithBrackets.fir.kt
@@ -0,0 +1,16 @@
+annotation class Ann
+
+class C {
+    fun test() {
+        @Ann<!SYNTAX!><!>
+    }
+
+    fun foo() {
+        class Local {
+            @Ann<!SYNTAX!><!>
+        }
+    }
+    @Ann<!SYNTAX!><!>
+}
+
+@Ann<!SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/Deprecated.fir.kt b/compiler/testData/diagnostics/tests/annotations/Deprecated.fir.kt
new file mode 100644
index 00000000000..9032870147a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/Deprecated.fir.kt
@@ -0,0 +1,5 @@
+import java.lang.Deprecated as deprecated
+
+@java.lang.Deprecated fun foo() {}
+
+@deprecated fun foo1() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/JavaAnnotationConstructors.fir.kt b/compiler/testData/diagnostics/tests/annotations/JavaAnnotationConstructors.fir.kt
new file mode 100644
index 00000000000..0fa0d5677dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/JavaAnnotationConstructors.fir.kt
@@ -0,0 +1,10 @@
+import java.lang.annotation.Retention
+import java.lang.annotation.Target
+import java.lang.annotation.*
+
+@java.lang.annotation.Retention(RetentionPolicy.CLASS)
+annotation class my
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR)
+annotation class my1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/MultiDeclaration.fir.kt b/compiler/testData/diagnostics/tests/annotations/MultiDeclaration.fir.kt
new file mode 100644
index 00000000000..7ac8fbe9641
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/MultiDeclaration.fir.kt
@@ -0,0 +1,9 @@
+annotation class Ann
+
+data class Pair(val x: Int, val y: Int)
+
+fun foo(): Int {
+    @Ann val (a, b) = Pair(12, 34)
+    @Err val (c, d) = Pair(56, 78)
+    return a + b + c + d
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/MutuallyRecursivelyAnnotatedGlobalFunction.fir.kt b/compiler/testData/diagnostics/tests/annotations/MutuallyRecursivelyAnnotatedGlobalFunction.fir.kt
new file mode 100644
index 00000000000..6ea315c899a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/MutuallyRecursivelyAnnotatedGlobalFunction.fir.kt
@@ -0,0 +1,4 @@
+// Functions can be recursively annotated
+annotation class ann(val x: Int)
+@ann(bar()) fun foo() = 1
+@ann(foo()) fun bar() = 2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/NonAnnotationClass.fir.kt b/compiler/testData/diagnostics/tests/annotations/NonAnnotationClass.fir.kt
new file mode 100644
index 00000000000..b606948ff6c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/NonAnnotationClass.fir.kt
@@ -0,0 +1,3 @@
+class Foo
+
+@Foo class Bar
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotated.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotated.fir.kt
new file mode 100644
index 00000000000..86351a434ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotated.fir.kt
@@ -0,0 +1,3 @@
+// Class CAN be recursively annotated
+@RecursivelyAnnotated(1)
+annotation class RecursivelyAnnotated(val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedFunctionParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedFunctionParameter.fir.kt
new file mode 100644
index 00000000000..1319481c187
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedFunctionParameter.fir.kt
@@ -0,0 +1,3 @@
+// Function parameter CAN be recursively annotated
+annotation class ann(val x: Int)
+fun foo(@ann(foo(1)) x: Int): Int = x
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedGlobalFunction.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedGlobalFunction.fir.kt
new file mode 100644
index 00000000000..b99a231e627
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedGlobalFunction.fir.kt
@@ -0,0 +1,3 @@
+// Functions can be recursively annotated
+annotation class ann(val x: Int)
+@ann(foo()) fun foo() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedGlobalProperty.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedGlobalProperty.fir.kt
new file mode 100644
index 00000000000..638a1728975
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedGlobalProperty.fir.kt
@@ -0,0 +1,3 @@
+// Properties can be recursively annotated
+annotation class ann(val x: Int)
+@ann(x) const val x: Int = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameter.fir.kt
new file mode 100644
index 00000000000..e4277530222
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameter.fir.kt
@@ -0,0 +1,2 @@
+// Class constructor parameter CAN be recursively annotated
+annotation class RecursivelyAnnotated(@RecursivelyAnnotated(1) val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameterType.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameterType.fir.kt
new file mode 100644
index 00000000000..f3227d7dccd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameterType.fir.kt
@@ -0,0 +1,3 @@
+// Class constructor parameter type CAN be recursively annotated
+@Target(AnnotationTarget.TYPE)
+annotation class RecursivelyAnnotated(val x: @RecursivelyAnnotated(1) Int)
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameterWithAt.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameterWithAt.fir.kt
new file mode 100644
index 00000000000..e4277530222
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedParameterWithAt.fir.kt
@@ -0,0 +1,2 @@
+// Class constructor parameter CAN be recursively annotated
+annotation class RecursivelyAnnotated(@RecursivelyAnnotated(1) val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedProperty.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedProperty.fir.kt
new file mode 100644
index 00000000000..0f5f8a50c52
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyAnnotatedProperty.fir.kt
@@ -0,0 +1,5 @@
+// Properties can be recursively annotated
+annotation class ann(val x: Int)
+class My {
+    @ann(x) val x: Int = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RecursivelyIncorrectlyAnnotatedParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/RecursivelyIncorrectlyAnnotatedParameter.fir.kt
new file mode 100644
index 00000000000..b7696796635
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RecursivelyIncorrectlyAnnotatedParameter.fir.kt
@@ -0,0 +1,2 @@
+// Class constructor parameter CAN be recursively annotated
+class RecursivelyAnnotated(@RecursivelyAnnotated(1) val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RetentionsOfAnnotationWithExpressionTarget_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/RetentionsOfAnnotationWithExpressionTarget_after.fir.kt
new file mode 100644
index 00000000000..a20223575a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RetentionsOfAnnotationWithExpressionTarget_after.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +RestrictRetentionForExpressionAnnotations
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class TestRetentionSource
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.BINARY)
+annotation class TestRetentionBinary
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.RUNTIME)
+annotation class TestRetentionRuntime
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/RetentionsOfAnnotationWithExpressionTarget_before.fir.kt b/compiler/testData/diagnostics/tests/annotations/RetentionsOfAnnotationWithExpressionTarget_before.fir.kt
new file mode 100644
index 00000000000..a3cfeb4173d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/RetentionsOfAnnotationWithExpressionTarget_before.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: -RestrictRetentionForExpressionAnnotations
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class TestRetentionSource
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.BINARY)
+annotation class TestRetentionBinary
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.RUNTIME)
+annotation class TestRetentionRuntime
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/UnresolvedAnnotationOnObject.fir.kt b/compiler/testData/diagnostics/tests/annotations/UnresolvedAnnotationOnObject.fir.kt
new file mode 100644
index 00000000000..6d25c741128
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/UnresolvedAnnotationOnObject.fir.kt
@@ -0,0 +1,9 @@
+package test
+
+// Checks that there is no rewrite error at ANNOTATION slice because of resolving annotations for object in lazy resolve and resolving
+// object as property (method tries to resolve annotations too).
+
+@BadAnnotation
+object SomeObject
+
+val some = SomeObject
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/WrongAnnotationArgsOnObject.fir.kt b/compiler/testData/diagnostics/tests/annotations/WrongAnnotationArgsOnObject.fir.kt
new file mode 100644
index 00000000000..3dc7d2d7bd2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/WrongAnnotationArgsOnObject.fir.kt
@@ -0,0 +1,8 @@
+package test
+
+@BadAnnotation(1)
+object SomeObject
+
+val some = SomeObject
+
+annotation class BadAnnotation(val s: String)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotatedExpressionInsideAnnotation.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotatedExpressionInsideAnnotation.fir.kt
new file mode 100644
index 00000000000..03e91388a2e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotatedExpressionInsideAnnotation.fir.kt
@@ -0,0 +1,11 @@
+// SKIP_ERRORS_BEFORE
+
+annotation class X(val value: Y, val y: Y)
+annotation class Y()
+
+@X(@Y()<!SYNTAX!><!>, y = Y())
+fun foo1() {
+}
+@X(@Y()<!SYNTAX!><!>, y = @Y()<!SYNTAX!><!>)
+fun foo2() {
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationInheritance.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationInheritance.fir.kt
new file mode 100644
index 00000000000..dd3c7ea6d62
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationInheritance.fir.kt
@@ -0,0 +1,8 @@
+val a = object: T {}
+open class C
+interface T
+
+annotation class Ann: C()
+annotation class Ann2: T
+annotation class Ann3: T by a
+annotation class Ann4: C(), T
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationModifier.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationModifier.fir.kt
new file mode 100644
index 00000000000..a62a21476bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationModifier.fir.kt
@@ -0,0 +1,15 @@
+annotation class B
+
+class A {
+   annotation companion object {}
+}
+
+annotation object O {}
+
+annotation interface T {}
+
+annotation fun f() = 0
+
+annotation val x = 0
+
+annotation var y = 0
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationOnParameterInFunctionType.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationOnParameterInFunctionType.fir.kt
new file mode 100644
index 00000000000..63606691a1c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationOnParameterInFunctionType.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+annotation class Ann
+
+fun f(@Ann x: Int) {}
+
+val inVal: (@Ann x: Int)->Unit = {}
+
+fun inParam(fn: (@Ann x: Int)->Unit) {}
+
+fun inParamNested(fn1: (fn2: (@Ann n: Int)->Unit)->Unit) {}
+
+fun inReturn(): (@Ann x: Int)->Unit = {}
+
+class A : (@Ann Int)->Unit {
+    override fun invoke(p1: Int) {
+        var lambda: (@Ann x: Int)->Unit = {}
+    }
+
+    val prop: (@Ann x: Int)->Unit
+        get(): (@Ann x: Int)->Unit = {}
+}
+
+@Target(AnnotationTarget.TYPE)
+annotation class TypeAnn
+
+val onType: (@TypeAnn A).(@Ann a: @TypeAnn A, @TypeAnn A)->@TypeAnn A? = { null }
+
+fun (@TypeAnn A).extFun(@Ann a: @TypeAnn A): @TypeAnn A? = null
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/annotationConstructorDefaultParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/annotationConstructorDefaultParameter.fir.kt
new file mode 100644
index 00000000000..2e0eb6f8ce1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/annotationConstructorDefaultParameter.fir.kt
@@ -0,0 +1,12 @@
+const val iConst = 42
+val iVal = 42
+fun iFun() = 42
+
+annotation class Ann(val x: Int)
+annotation class Test1(val x: Int = 42)
+annotation class Test2(val x: Int = iConst)
+annotation class Test3(val x: Int = 1 + iConst + 1)
+annotation class Test4(val x: Int = iVal)
+annotation class Test5(val x: Int = 1 + iVal + 1)
+annotation class Test6(val x: Int = iFun())
+annotation class Test7(val x: Int = 1 + iFun() + 1)
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/booleanLocalVal.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/booleanLocalVal.fir.kt
new file mode 100644
index 00000000000..332422e5e47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/booleanLocalVal.fir.kt
@@ -0,0 +1,6 @@
+annotation class Ann(vararg val i: Boolean)
+fun foo() {
+    val bool1 = true
+
+    @Ann(bool1) val a = bool1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/compareAndEquals.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/compareAndEquals.fir.kt
new file mode 100644
index 00000000000..5156c7bbb89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/compareAndEquals.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+annotation class Ann(vararg val i: Boolean)
+fun foo() {
+    val a1 = 1 > 2
+    val a2 = 1 == 2
+    val a3 = a1 == a2
+    val a4 = a1 > a2
+
+    @Ann(
+            a1,
+            a2,
+            a3,
+            a1 > a2,
+            a1 == a2
+    ) val b = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/enumConst_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/enumConst_after.fir.kt
new file mode 100644
index 00000000000..e5cdcbffc91
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/enumConst_after.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +ProhibitNonConstValuesAsVarargsInAnnotations
+
+annotation class AnnE(val i: MyEnum)
+
+@AnnE(e)
+class Test
+
+val e: MyEnum = MyEnum.A
+
+enum class MyEnum {
+    A
+}
+
+@AnnE(Test())
+class Test2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/enumConst_before.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/enumConst_before.fir.kt
new file mode 100644
index 00000000000..35d43f1e3e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/enumConst_before.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -ProhibitNonConstValuesAsVarargsInAnnotations
+
+annotation class AnnE(val i: MyEnum)
+
+@AnnE(e)
+class Test
+
+val e: MyEnum = MyEnum.A
+
+enum class MyEnum {
+    A
+}
+
+@AnnE(Test())
+class Test2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/javaProperties.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/javaProperties.fir.kt
new file mode 100644
index 00000000000..9d6c13de8c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/javaProperties.fir.kt
@@ -0,0 +1,25 @@
+// FILE: Test.java
+public class Test {
+    public static int i1 = 1;
+    public static final int i2 = 1;
+    public static final int i3 = i1;
+    public static final int i4 = i2;
+    public static int i5 = i1;
+    public static int i6 = i2;
+
+    public final int i7 = 1;
+}
+
+// FILE: a.kt
+annotation class Ann(vararg val i: Int)
+
+@Ann(
+        Test.i1,
+        Test.i2,
+        Test.i3,
+        Test.i4,
+        Test.i5,
+        Test.i6,
+        Test().i7
+)
+class A
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/kotlinProperties.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/kotlinProperties.fir.kt
new file mode 100644
index 00000000000..b580df33fee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/kotlinProperties.fir.kt
@@ -0,0 +1,18 @@
+annotation class Ann(vararg val i: Int)
+
+@Ann(
+        i1,
+        i2,
+        i3,
+        i4,
+        i5,
+        i6
+)
+class Test
+
+var i1 = 1  // var
+const val i2 = 1  // val
+val i3 = i1 // val with var in initializer
+const val i4 = i2 // val with val in initializer
+var i5 = i1 // var with var in initializer
+var i6 = i2 // var with val in initializer
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/standaloneInExpression.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/standaloneInExpression.fir.kt
new file mode 100644
index 00000000000..5283fe5f70a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/standaloneInExpression.fir.kt
@@ -0,0 +1,18 @@
+annotation class AnnE(val i: String)
+
+enum class MyEnum {
+    A
+}
+
+@AnnE("1" + MyEnum.A)
+class Test
+
+@AnnE("1" + MyEnum::class)
+class Test2
+
+@AnnE("1" + AnnE("23"))
+class Test3
+
+@AnnE("1" + arrayOf("23", "34"))
+class Test4
+
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/strings.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/strings.fir.kt
new file mode 100644
index 00000000000..a90f4b533c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationParameterMustBeConstant/strings.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+annotation class Ann(vararg val i: String)
+
+const val topLevel = "topLevel"
+
+fun foo() {
+    val a1 = "a"
+    val a2 = "b"
+    val a3 = a1 + a2
+
+    val a4 = 1
+    val a5 = 1.0
+
+    @Ann(
+            a1,
+            a2,
+            a3,
+            "$topLevel",
+            "$a1",
+            "$a1 $topLevel",
+            "$a4",
+            "$a5",
+            a1 + a2,
+            "a" + a2,
+            "a" + topLevel,
+            "a" + a4
+    ) val b = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationRenderingInTypes.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationRenderingInTypes.fir.kt
new file mode 100644
index 00000000000..42ba06bd17d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationRenderingInTypes.fir.kt
@@ -0,0 +1,26 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -UNUSED_ANONYMOUS_PARAMETER
+// !WITH_NEW_INFERENCE
+
+fun f1(x: String) {}
+fun f2(f: () -> Unit) {}
+fun test1() = <!INAPPLICABLE_CANDIDATE!>f2<!>(::f1)
+
+
+@Target(AnnotationTarget.TYPE_PARAMETER,  AnnotationTarget.TYPE)
+annotation class Ann
+
+fun <@Ann R : @Ann Any> f3(a: Array<@Ann R>): Array<@Ann R?> =  null!!
+
+fun test2(a: @Ann Array<in @Ann Int>) {
+    val r: Array<in Int?> = <!INAPPLICABLE_CANDIDATE!>f3<!>(a)
+}
+
+
+var test3: Int = 0
+    set(s: @Ann String) {}
+
+
+fun f4(fn: (@Ann Int, @Ann Int) -> Unit) {}
+
+val test4 = <!INAPPLICABLE_CANDIDATE!>f4<!> { single -> }
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationsOnLambdaAsCallArgument.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationsOnLambdaAsCallArgument.fir.kt
new file mode 100644
index 00000000000..33f552e47e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationsOnLambdaAsCallArgument.fir.kt
@@ -0,0 +1,19 @@
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Ann(val x: Int = 1)
+
+inline fun bar(block: () -> Int): Int = block()
+
+fun foo() {
+    bar() @Ann(1) @Ann(2) { 101 }
+    bar() @Ann(3) { 102 }
+
+    bar @Ann l1@ {
+        return@l1 103
+    }
+
+    bar @Ann("") {
+        104
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/annotationsOnNullableTypes.fir.kt b/compiler/testData/diagnostics/tests/annotations/annotationsOnNullableTypes.fir.kt
new file mode 100644
index 00000000000..840cb49a5de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/annotationsOnNullableTypes.fir.kt
@@ -0,0 +1,44 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER
+
+@Target(AnnotationTarget.TYPE)
+annotation class a
+
+@Target(AnnotationTarget.TYPE)
+annotation class b(val i: Int)
+
+annotation class c
+
+fun foo(i: @a Int?) {}
+
+fun foo(l: List<@a Int?>) {}
+
+fun @a Int?.bar() {}
+
+val baz: @a Int? = 1
+
+
+fun foo1(i: @b(1) Int?) {}
+
+fun foo1(l: List<@b(1) Int?>) {}
+
+fun @b(1) Int?.bar1() {}
+
+val baz1: @b(1) Int? = 1
+
+
+fun foo2(i: @[a b(1)] Int?) {}
+
+fun foo2(l: List<@[a b(1)] Int?>) {}
+
+fun @[a b(1)] Int?.bar2() {}
+
+val baz2: @[a b(1)] Int? = 1
+
+
+fun foo3(i: @c Int?) {}
+
+fun foo3(l: List<@c Int?>) {}
+
+fun @c Int?.bar3() {}
+
+val baz3: @c Int? = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/atAnnotationResolve.fir.kt b/compiler/testData/diagnostics/tests/annotations/atAnnotationResolve.fir.kt
new file mode 100644
index 00000000000..b2e39f4b44a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/atAnnotationResolve.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS,
+        AnnotationTarget.CONSTRUCTOR, AnnotationTarget.FUNCTION,
+        AnnotationTarget.EXPRESSION, AnnotationTarget.PROPERTY)
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Ann(val x: Int = 6)
+
+@Ann(1) @Ann(2) @Ann(3) private class A @Ann constructor() {
+    @Ann(x = 5) fun foo() {
+        1 + @Ann(1) 1 * @Ann("") 6
+
+        @Ann fun local() {}
+    }
+
+    @Ann val x = 1
+
+    fun bar(x: @Ann(1) @Ann(2) @Ann(3) Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/blockLevelOnTheSameLineWarning.fir.kt b/compiler/testData/diagnostics/tests/annotations/blockLevelOnTheSameLineWarning.fir.kt
new file mode 100644
index 00000000000..467dbcb69f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/blockLevelOnTheSameLineWarning.fir.kt
@@ -0,0 +1,62 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class Ann1
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class Ann2(val x: String)
+
+fun bar() {}
+fun bar(block: () -> Unit) {}
+
+fun foo(y: IntArray) {
+    @Ann1 bar()
+    @Ann1 bar() { }
+    @Ann1 bar { }
+
+    @Ann2("") bar()
+    @Ann2("") bar() { }
+    @Ann2("") bar { }
+
+    @Ann1 @Ann2("") bar()
+
+    var x = 1
+
+    @Ann1 ++x
+    @Ann1 x++
+    @Ann2("") ++x
+    @Ann2("") x++
+    @Ann1 @Ann2("") ++x
+    @Ann1 @Ann2("") x++
+
+    @Ann1 y[0]
+
+    @Ann1 { x: Int -> x }
+    @Ann1 <!UNRESOLVED_REFERENCE!>{ x: Int -> x }(1)<!>
+    @Ann1 object { fun foo() = 1 }
+    @Ann1 object { fun foo() = 1 }.foo()
+
+    @Ann1() (x * x)
+    var z = 1
+    @Ann1 x + z
+
+    @Ann1 x = x + 2
+    @Ann1 x += z + 2
+
+    @Ann1 x + 6 * 2 > 0
+    @Ann1 x * 6 + 2 > 0
+
+    @Ann1 object { operator fun plus(x: Int) = 1 } + 1
+    @Ann1 object { operator fun plus(x: Int) = 1 } + 1 * 4 > 0
+
+    @Ann1 x foo z + 8
+
+    1 + @Ann1 x
+    1 + @Ann1 x * z + 8
+
+    x foo @Ann1 z + 8
+}
+
+infix fun Int.foo(other: Int) = 1
diff --git a/compiler/testData/diagnostics/tests/annotations/deprecatedRepeatable.fir.kt b/compiler/testData/diagnostics/tests/annotations/deprecatedRepeatable.fir.kt
new file mode 100644
index 00000000000..df340589e70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/deprecatedRepeatable.fir.kt
@@ -0,0 +1,11 @@
+// FULL_JDK
+
+import java.lang.annotation.Repeatable
+
+@java.lang.annotation.Repeatable(Annotations::class) annotation class RepAnn
+
+@Repeatable(OtherAnnotations::class) annotation class OtherAnn
+
+annotation class Annotations(vararg val value: RepAnn)
+
+annotation class OtherAnnotations(vararg val value: OtherAnn)
diff --git a/compiler/testData/diagnostics/tests/annotations/extensionFunctionType.fir.kt b/compiler/testData/diagnostics/tests/annotations/extensionFunctionType.fir.kt
new file mode 100644
index 00000000000..f034031bb3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/extensionFunctionType.fir.kt
@@ -0,0 +1,11 @@
+// This test checks that annotations on extension function types are preserved. See the corresponding .txt file
+
+@Target(AnnotationTarget.TYPE)
+annotation class ann
+
+interface Some {
+    fun f1(): String.() -> Int
+    fun f2(): @ExtensionFunctionType() (String.() -> Int)
+    fun f3(): @ann String.() -> Int
+    fun f4(): @ExtensionFunctionType @ann() (String.() -> Int)
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/forParameterAnnotationResolve.fir.kt b/compiler/testData/diagnostics/tests/annotations/forParameterAnnotationResolve.fir.kt
new file mode 100644
index 00000000000..fd63f5b0969
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/forParameterAnnotationResolve.fir.kt
@@ -0,0 +1,14 @@
+annotation class Ann(val x: Int)
+
+data class A(val x: Int, val y: Int)
+
+fun bar(): Array<A> = null!!
+
+fun foo() {
+    for (@Ann(1) i in 1..100) {}
+    for (@Ann(2) i in 1..100) {}
+
+    for (@Ann(3) (x, @Ann(4) y) in bar()) {}
+
+    for (@Err() (x,y) in bar()) {}
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/functionalTypes/nonParenthesizedAnnotationsWithError.fir.kt b/compiler/testData/diagnostics/tests/annotations/functionalTypes/nonParenthesizedAnnotationsWithError.fir.kt
new file mode 100644
index 00000000000..9936973da17
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/functionalTypes/nonParenthesizedAnnotationsWithError.fir.kt
@@ -0,0 +1,70 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -CAST_NEVER_SUCCEEDS -CANNOT_CHECK_FOR_ERASED -UNCHECKED_CAST -UNUSED_ANONYMOUS_PARAMETER
+// SKIP_TXT
+// Issue: KT-31734
+
+@Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Foo
+
+fun foo1(x: @Foo () -> Unit) = x as Iterable<@Foo () -> Unit>?
+
+fun foo2() = null as @Foo () -> Unit
+
+fun foo3(x: Any?) {
+    if (x is (@Foo () -> Unit)?) {
+
+    }
+}
+
+fun foo4(x: Any) = x is @Foo () -> (() -> Unit?)
+
+fun foo5(x: Any): @Foo () -> Unit = x as @Foo() @[Foo Foo()] @Foo () -> Unit
+
+fun foo6() {
+    val x: @Foo() @[Foo Foo()] @Foo () -> Unit = {}
+}
+
+fun foo7() {
+    val x: @Foo (@Foo () -> Unit) -> Unit = { x: @Foo () -> Unit -> }
+}
+
+fun foo8(x: Any?) {
+    val x: (@Foo () -> Unit)? = {}
+}
+
+fun foo9(x: (@Foo () -> Unit)?) = x as Iterable<(@Foo () -> Unit?)?>?
+
+fun foo10(x: @[Foo] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo11(x: @[Foo ] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo12(x: @[Foo/**/] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+val foo13: @Foo (x: @Foo Any) -> Unit get() = {}
+
+val foo14: @Foo (x: @Foo () -> Unit) -> Unit get() = {}
+
+val foo15: @Foo () @Foo () -> Unit get() = {}
+
+val foo16: @Foo @Foo () @Foo () -> Unit get() = {}
+
+val foo17: @Foo() @Foo () @Foo () -> Unit get() = {}
+
+val foo18: @Foo()@Foo () @Foo () -> Unit get() = {}
+
+val foo19: @Foo@Foo () @Foo () -> Unit get() = {}
+
+val foo20: @Foo@Foo () -> Unit get() = {}
+
+val foo21: @Foo()@Foo () -> Unit get() = {}
+
+val foo22: @Foo (x: @Foo () -> Unit) -> Unit get() = {}
+
+val foo23: @Foo (@Foo () -> Unit) -> Unit get() = {}
+
+val foo24: @Foo (@Foo () -> Unit, @Foo () -> Unit) -> Unit get() = {x, y -> }
+
+val foo25: @Foo (x: @Foo Any, @Foo Any) -> Unit get() = {x, y -> }
+
+val foo26: @Foo suspend () -> Unit = {}
diff --git a/compiler/testData/diagnostics/tests/annotations/functionalTypes/nonParenthesizedAnnotationsWithoutError.fir.kt b/compiler/testData/diagnostics/tests/annotations/functionalTypes/nonParenthesizedAnnotationsWithoutError.fir.kt
new file mode 100644
index 00000000000..87c031e3a6a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/functionalTypes/nonParenthesizedAnnotationsWithoutError.fir.kt
@@ -0,0 +1,67 @@
+// !LANGUAGE: +NonParenthesizedAnnotationsOnFunctionalTypes
+// !DIAGNOSTICS: -UNUSED_VARIABLE -CAST_NEVER_SUCCEEDS -CANNOT_CHECK_FOR_ERASED -UNCHECKED_CAST -UNUSED_ANONYMOUS_PARAMETER
+// SKIP_TXT
+// Issue: KT-31734
+
+@Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Foo
+
+class MyClass
+
+fun foo1(x: @Foo () -> Unit) = x as Iterable<@Foo () -> Unit>?
+
+fun foo2() = null as @Foo () -> Unit
+
+fun foo3(x: Any?) {
+    if (x is (@Foo () -> Unit)?) {
+
+    }
+}
+
+fun foo4(x: Any) = x is @Foo () -> (() -> Unit?)
+
+fun foo5(x: Any): @Foo () -> Unit = x as @Foo() @[Foo Foo()] @Foo () -> Unit
+
+fun foo6() {
+    val x: @Foo() @[Foo Foo()] @Foo () -> Unit = {}
+}
+
+fun foo7() {
+    val x: @Foo (@Foo () -> Unit) -> Unit = { x: @Foo () -> Unit -> }
+}
+
+fun foo10(x: @[Foo()] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo11(x: @[Foo] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo12(x: @[Foo ] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo13(x: @[Foo/**/] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+val foo14: @Foo (x: @Foo () -> Unit) -> Unit get() = {}
+
+val foo15: @Foo () @Foo () -> Unit get() = {}
+
+val foo16: @Foo @Foo () @Foo () -> Unit get() = {}
+
+val foo17: @Foo() @Foo () @Foo () -> Unit get() = {}
+
+val foo18: @Foo()@Foo () @Foo () -> Unit get() = {}
+
+val foo19: @Foo@Foo () @Foo () -> Unit get() = {}
+
+val foo20: @Foo@Foo () -> Unit get() = {}
+
+val foo21: @Foo()@Foo () -> Unit get() = {}
+
+val foo22: @Foo (x: @Foo () -> Unit) -> Unit get() = {}
+
+val foo23: @Foo (@Foo () -> Unit) -> Unit get() = {}
+
+val foo24: @Foo (@Foo () -> Unit, @Foo () -> Unit) -> Unit get() = {x, y -> }
+
+val foo25: @Foo (x: @Foo Any, @Foo Any) -> Unit get() = {x, y -> }
+
+val foo26: @Foo suspend () -> Unit = {}
diff --git a/compiler/testData/diagnostics/tests/annotations/functionalTypes/parenthesizedAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/functionalTypes/parenthesizedAnnotations.fir.kt
new file mode 100644
index 00000000000..89371321a75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/functionalTypes/parenthesizedAnnotations.fir.kt
@@ -0,0 +1,46 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -CAST_NEVER_SUCCEEDS -CANNOT_CHECK_FOR_ERASED -UNCHECKED_CAST -UNUSED_ANONYMOUS_PARAMETER
+// SKIP_TXT
+// Issue: KT-31734
+
+@Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Foo
+
+fun foo1(x: @Foo() () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo2() = null as @Foo() () -> Unit
+
+fun foo3(x: Any?) {
+    if (x is (@Foo() () -> Unit)?) {
+
+    }
+}
+
+fun foo4(x: Any) = x is @Foo() () -> (() -> Unit?)
+
+fun foo5(x: Any): @Foo() () -> Unit = x as @Foo () @[Foo Foo ()] @Foo() () -> Unit
+
+fun foo6() {
+    val x: @Foo() @[Foo Foo()] @Foo() () -> Unit = {}
+}
+
+fun foo7() {
+    val x: @Foo() (@Foo() () -> Unit) -> Unit = { x: @Foo() () -> Unit -> }
+}
+
+fun foo8(x: @[Foo() ] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo9(x: @[Foo()] () -> Unit) = x as Iterable<@Foo() () -> Unit>?
+
+fun foo10() {
+    val x: @Foo () @Foo () () -> Unit = {}
+}
+
+fun foo11() {
+    val x: @Foo @Foo () () -> Unit = {}
+}
+
+fun foo12() {
+    val x: @Foo() @Foo () () -> Unit = {}
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/illegalRequireKotlinValue.fir.kt b/compiler/testData/diagnostics/tests/annotations/illegalRequireKotlinValue.fir.kt
new file mode 100644
index 00000000000..f253cd804d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/illegalRequireKotlinValue.fir.kt
@@ -0,0 +1,38 @@
+@file:Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+package test
+
+import kotlin.internal.RequireKotlin
+
+@RequireKotlin("")
+fun f01() {}
+
+@RequireKotlin("x")
+fun f02() {}
+
+@RequireKotlin("1")
+fun f03() {}
+
+@RequireKotlin("1.0-beta")
+fun f04() {}
+
+@RequireKotlin("1.1.0-dev-1111")
+fun f05() {}
+
+@RequireKotlin("1.5.3.7")
+fun f06() {}
+
+@RequireKotlin("1..0")
+fun f07() {}
+
+@RequireKotlin(" 1.0")
+fun f08() {}
+
+
+@RequireKotlin("1.1")
+fun ok1() {}
+
+@RequireKotlin("1.1.0")
+fun ok2() {}
+
+@RequireKotlin("0.0.0")
+fun ok3() {}
diff --git a/compiler/testData/diagnostics/tests/annotations/illegalSinceKotlinValue.fir.kt b/compiler/testData/diagnostics/tests/annotations/illegalSinceKotlinValue.fir.kt
new file mode 100644
index 00000000000..e5b29c8b002
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/illegalSinceKotlinValue.fir.kt
@@ -0,0 +1,74 @@
+@SinceKotlin("")
+fun f01() {}
+
+@SinceKotlin("x")
+fun f02() {}
+
+@SinceKotlin("1")
+fun f03() {}
+
+@SinceKotlin("1,0")
+fun f04() {}
+
+@SinceKotlin("1,0,1")
+fun f05() {}
+
+@SinceKotlin("a.b")
+fun f06() {}
+
+@SinceKotlin("1.a")
+fun f07() {}
+
+@SinceKotlin("1.0.a")
+fun f08() {}
+
+@SinceKotlin("1.0-beta")
+fun f09() {}
+
+@SinceKotlin("1.1.0-dev-1111")
+fun f10() {}
+
+@SinceKotlin("1.1.0+rc")
+fun f11() {}
+
+@SinceKotlin("1.5.3.7")
+fun f12() {}
+
+@SinceKotlin("01.1")
+fun f13() {}
+
+@SinceKotlin("1.01")
+fun f14() {}
+
+@SinceKotlin("-1.0")
+fun f15() {}
+
+@SinceKotlin("1.-1.0")
+fun f16() {}
+
+@SinceKotlin("0.00.1")
+fun f17() {}
+
+@SinceKotlin("1..0")
+fun f18() {}
+
+@SinceKotlin(" 1.0")
+fun f19() {}
+
+@SinceKotlin("1.0 ")
+fun f20() {}
+
+
+
+
+@SinceKotlin("1.1")
+fun ok1() {}
+
+@SinceKotlin("1.1.0")
+fun ok2() {}
+
+@SinceKotlin("0.0.0")
+fun ok3() {}
+
+@SinceKotlin("123456789012345678901234567890.123456789012345678901234567890.123456789012345678901234567890")
+fun ok4() {}
diff --git a/compiler/testData/diagnostics/tests/annotations/inheritFromAnnotationClass.fir.kt b/compiler/testData/diagnostics/tests/annotations/inheritFromAnnotationClass.fir.kt
new file mode 100644
index 00000000000..17b9a770ad2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/inheritFromAnnotationClass.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -FINAL_SUPERTYPE
+// This error needs to be suppressed to cause light class generation
+
+class Foo : Target()
diff --git a/compiler/testData/diagnostics/tests/annotations/inheritFromAnnotationClass2.fir.kt b/compiler/testData/diagnostics/tests/annotations/inheritFromAnnotationClass2.fir.kt
new file mode 100644
index 00000000000..7a63ab0f4e5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/inheritFromAnnotationClass2.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -SUPERTYPES_FOR_ANNOTATION_CLASS -VIRTUAL_MEMBER_HIDDEN -FINAL_SUPERTYPE -MISSING_DEPENDENCY_SUPERCLASS
+// These errors need to be suppressed to cause light class generation
+// FILE: test.kt
+
+annotation class Ann : Target()
+
+annotation class Ann2(vararg val allowedTargets: AnnotationTarget) : Target()
+
+interface I : J {
+    override fun foo(): List<String> = throw Exception()
+}
+class C : I {
+    fun bar(): Set<Number> = throw Exception()
+}
+annotation class Ann3 : C()
+annotation class Ann4 : I
+
+// FILE: J.java
+
+import java.util.Collection;
+import kotlin.annotation.Target;
+
+public interface J extends Target {
+    Collection<String> foo();
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/invalidTypesInAnnotationConstructor.fir.kt b/compiler/testData/diagnostics/tests/annotations/invalidTypesInAnnotationConstructor.fir.kt
new file mode 100644
index 00000000000..73a5332afb9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/invalidTypesInAnnotationConstructor.fir.kt
@@ -0,0 +1,76 @@
+package test
+
+import java.lang.annotation.RetentionPolicy
+
+// CORRECT
+annotation class Ann1(val p1: Int,
+                      val p2: Byte,
+                      val p3: Short,
+                      val p4: Long,
+                      val p5: Double,
+                      val p6: Float,
+                      val p7: Char,
+                      val p8: Boolean)
+
+annotation class Ann2(val p1: String)
+annotation class Ann3(val p1: Ann1)
+annotation class Ann4(val p1: IntArray,
+                      val p2: ByteArray,
+                      val p3: ShortArray,
+                      val p4: LongArray,
+                      val p5: DoubleArray,
+                      val p6: FloatArray,
+                      val p7: CharArray,
+                      val p8: BooleanArray)
+
+annotation class Ann5(val p1: MyEnum)
+
+annotation class Ann6(val p: Class<*>)
+annotation class Ann7(val p: RetentionPolicy)
+
+annotation class Ann8(val p1: Array<String>,
+                      val p2: Array<Class<*>>,
+                      val p3: Array<MyEnum>,
+                      val p4: Array<Ann1>)
+
+annotation class Ann9(
+        val error: Unresolved = <!UNRESOLVED_REFERENCE!>Unresolved<!>.<!UNRESOLVED_REFERENCE!>VALUE<!>
+)
+
+
+// INCORRECT
+annotation class InAnn1(val p1: Int?,
+                        val p3: Short?,
+                        val p4: Long?,
+                        val p5: Double?,
+                        val p6: Float?,
+                        val p7: Char?,
+                        val p8: Boolean?)
+
+annotation class InAnn4(val p1: Array<Int>,
+                        val p2: Array<Int>?)
+
+annotation class InAnn6(val p:  Class<*>?)
+annotation class InAnn7(val p:  RetentionPolicy?)
+annotation class InAnn8(val p1: Array<Int>,
+                        val p2: Array<Int?>,
+                        val p3: Array<MyClass>,
+                        val p4: Array<IntArray>)
+
+annotation class InAnn9(val p: MyClass)
+
+annotation class InAnn10(val p1: String?)
+annotation class InAnn11(val p1: Ann1?)
+annotation class InAnn12(val p1: MyEnum?)
+
+annotation class InAnn13(vararg val p1: String,
+                        vararg val p2: Class<*>,
+                        vararg val p3: MyEnum,
+                        vararg val p4: Ann1,
+                        vararg val p5: Int)
+
+enum class MyEnum {
+    A
+}
+
+class MyClass
diff --git a/compiler/testData/diagnostics/tests/annotations/javaRepeatable.fir.kt b/compiler/testData/diagnostics/tests/annotations/javaRepeatable.fir.kt
new file mode 100644
index 00000000000..4cee7b2a11a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/javaRepeatable.fir.kt
@@ -0,0 +1,19 @@
+// FULL_JDK
+// FILE: RepeatableAnnotation.java
+
+import java.lang.annotation.Repeatable;
+
+@Repeatable(RepeatableAnnotations.class)
+public @interface RepeatableAnnotation {
+}
+
+// FILE: RepeatableAnnotations.java
+
+public @interface RepeatableAnnotations {
+    RepeatableAnnotation[] value();
+}
+
+// FILE: RepeatableUse.kt
+
+// Error should be gone when Java 8 Target will be available
+@RepeatableAnnotation @RepeatableAnnotation class My
diff --git a/compiler/testData/diagnostics/tests/annotations/javaRepeatableRetention.fir.kt b/compiler/testData/diagnostics/tests/annotations/javaRepeatableRetention.fir.kt
new file mode 100644
index 00000000000..7c63caeac1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/javaRepeatableRetention.fir.kt
@@ -0,0 +1,20 @@
+// FULL_JDK
+// FILE: RepeatableAnnotation.java
+
+import java.lang.annotation.*;
+
+@Repeatable(RepeatableAnnotations.class)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface RepeatableAnnotation {
+}
+
+// FILE: RepeatableAnnotations.java
+
+public @interface RepeatableAnnotations {
+    RepeatableAnnotation[] value();
+}
+
+// FILE: RepeatableUse.kt
+
+// Error should be gone when Java 8 Target will be available
+@RepeatableAnnotation @RepeatableAnnotation class My
diff --git a/compiler/testData/diagnostics/tests/annotations/javaUnrepeatable.fir.kt b/compiler/testData/diagnostics/tests/annotations/javaUnrepeatable.fir.kt
new file mode 100644
index 00000000000..204ca20c272
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/javaUnrepeatable.fir.kt
@@ -0,0 +1,9 @@
+// FILE: UnrepeatableAnnotation.java
+
+public @interface UnrepeatableAnnotation {
+
+}
+
+// FILE: UnrepeatableUse.kt
+
+@UnrepeatableAnnotation @UnrepeatableAnnotation class My
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/kt1860-negative.fir.kt b/compiler/testData/diagnostics/tests/annotations/kt1860-negative.fir.kt
new file mode 100644
index 00000000000..e19143ff1bd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/kt1860-negative.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+fun foo(@varargs f : Int) {}
+
+var bar : Int = 1
+  set(@varargs v) {}
+
+val x : (Int) -> Int = {@varargs x <!SYNTAX!>: Int -> x<!>}
+
+class Hello(@varargs args: Any) {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/kt1860-positive.fir.kt b/compiler/testData/diagnostics/tests/annotations/kt1860-positive.fir.kt
new file mode 100644
index 00000000000..ce6384ae9e7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/kt1860-positive.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+@Target(AnnotationTarget.VALUE_PARAMETER, AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class test
+
+fun foo(@test f : Int) {}
+
+var bar : Int = 1
+    set(@test v) {}
+
+val x : (Int) -> Int = {@test x <!SYNTAX!>: Int -> x<!>} // todo fix parser annotation on lambda parameter
+
+class Hello(@test args: Any) {
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/kt1886annotationBody_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/kt1886annotationBody_after.fir.kt
new file mode 100644
index 00000000000..db9574ebd15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/kt1886annotationBody_after.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +NestedClassesInAnnotations
+
+annotation class Annotation2() {
+    public val s: String = ""
+}
+
+annotation class Annotation3() {
+    public fun foo() {}
+}
+
+annotation class Annotation4() {
+    class Foo() {}
+}
+
+annotation class Annotation5() {
+    companion object {}
+}
+
+annotation class Annotation6() {
+    init {}
+}
+
+annotation class Annotation1() {}
+
+annotation class Annotation7(val name: String) {}
+
+annotation class Annotation8(var name: String = "") {}
+
+annotation class Annotation9(val name: String)
+
+annotation class Annotation10
diff --git a/compiler/testData/diagnostics/tests/annotations/kt1886annotationBody_before.fir.kt b/compiler/testData/diagnostics/tests/annotations/kt1886annotationBody_before.fir.kt
new file mode 100644
index 00000000000..4f8115d7162
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/kt1886annotationBody_before.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: -NestedClassesInAnnotations
+
+annotation class Annotation2() {
+    public val s: String = ""
+}
+
+annotation class Annotation3() {
+    public fun foo() {}
+}
+
+annotation class Annotation4() {
+    class Foo() {}
+}
+
+annotation class Annotation5() {
+    companion object {}
+}
+
+annotation class Annotation6() {
+    init {}
+}
+
+annotation class Annotation1() {}
+
+annotation class Annotation7(val name: String) {}
+
+annotation class Annotation8(var name: String = "") {}
+
+annotation class Annotation9(val name: String)
+
+annotation class Annotation10
diff --git a/compiler/testData/diagnostics/tests/annotations/missingValOnParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/missingValOnParameter.fir.kt
new file mode 100644
index 00000000000..41d19140eb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/missingValOnParameter.fir.kt
@@ -0,0 +1,5 @@
+annotation class Ann(
+        val a: Int,
+        var b: Int,
+        c: String
+        )
diff --git a/compiler/testData/diagnostics/tests/annotations/nestedClassesInAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/nestedClassesInAnnotations.fir.kt
new file mode 100644
index 00000000000..b347ffd50f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/nestedClassesInAnnotations.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +NestedClassesInAnnotations
+
+annotation class Foo {
+    class Nested
+
+    inner class Inner
+
+    enum class E { A, B }
+    object O
+    interface I
+    annotation class Anno(val e: E)
+
+    companion object {
+        val x = 1
+        const val y = ""
+    }
+
+
+    constructor(s: Int) {}
+    init {}
+    fun function() {}
+    val property get() = Unit
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/noNameProperty.fir.kt b/compiler/testData/diagnostics/tests/annotations/noNameProperty.fir.kt
new file mode 100644
index 00000000000..3fcd987d7ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/noNameProperty.fir.kt
@@ -0,0 +1 @@
+annotation class Ann(val x: Int, val<!SYNTAX!><!> )
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/onExpression.fir.kt b/compiler/testData/diagnostics/tests/annotations/onExpression.fir.kt
new file mode 100644
index 00000000000..9ffd58eb14a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/onExpression.fir.kt
@@ -0,0 +1,5 @@
+fun foo() = @ann 1
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class ann
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/onFunctionParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/onFunctionParameter.fir.kt
new file mode 100644
index 00000000000..f0b2fcb1e1c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/onFunctionParameter.fir.kt
@@ -0,0 +1,7 @@
+annotation class ann
+
+fun test(@ann p: Int) {
+
+}
+
+val bar = fun(@ann g: Int) {}
diff --git a/compiler/testData/diagnostics/tests/annotations/onInitializer.fir.kt b/compiler/testData/diagnostics/tests/annotations/onInitializer.fir.kt
new file mode 100644
index 00000000000..9cfe8761a65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/onInitializer.fir.kt
@@ -0,0 +1,11 @@
+class A {
+    @ann init {}
+    @aaa init {}
+}
+
+interface T {
+    @ann init {}
+    @aaa init {}
+}
+
+annotation class ann
diff --git a/compiler/testData/diagnostics/tests/annotations/onLoops.fir.kt b/compiler/testData/diagnostics/tests/annotations/onLoops.fir.kt
new file mode 100644
index 00000000000..2ec18eb93d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/onLoops.fir.kt
@@ -0,0 +1,12 @@
+fun test() {
+    @ann
+    while (2 < 1) {}
+
+    @ann
+    do {} while (2 < 1)
+
+    @ann
+    for (i in 1..2) {}
+}
+
+annotation class ann
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/onLoopsUnreachable.fir.kt b/compiler/testData/diagnostics/tests/annotations/onLoopsUnreachable.fir.kt
new file mode 100644
index 00000000000..2500c6f6f4c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/onLoopsUnreachable.fir.kt
@@ -0,0 +1,12 @@
+fun test() {
+    @ann
+    while (2 > 1) {}
+
+    @ann
+    do {} while (2 > 1)
+
+    @ann
+    for (i in 1..2) {}
+}
+
+annotation class ann
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/onMultiDeclaration.fir.kt b/compiler/testData/diagnostics/tests/annotations/onMultiDeclaration.fir.kt
new file mode 100644
index 00000000000..b9c8cf57036
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/onMultiDeclaration.fir.kt
@@ -0,0 +1,7 @@
+fun test(): Any? {
+    @ann val (a, b) = P(1, 1)
+    return a + b
+}
+
+annotation class ann
+data class P(val a: Int, val b: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/annotationAsArg.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/annotationAsArg.fir.kt
new file mode 100644
index 00000000000..5484366eef0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/annotationAsArg.fir.kt
@@ -0,0 +1,14 @@
+class Annotation(val x: Int) {
+    fun baz() {}
+    fun bar() = x
+}
+
+fun foo(annotation: Annotation): Int {
+    if (annotation.bar() == 0) {
+        annotation.baz()
+        return 0
+    }
+    else {
+        return -1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/annotationAsArgComplex.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/annotationAsArgComplex.fir.kt
new file mode 100644
index 00000000000..e2c064206da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/annotationAsArgComplex.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+class Annotation {
+    fun setProblemGroup() {}
+    fun getQuickFixes() = 0
+}
+
+fun registerQuickFix(annotation: Annotation) {
+    annotation.setProblemGroup()
+    val fixes = annotation.getQuickFixes()
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/assignment.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/assignment.fir.kt
new file mode 100644
index 00000000000..53727d0796c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/assignment.fir.kt
@@ -0,0 +1,10 @@
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class ExprAnn
+
+fun foo(): Int {
+    var a: Int
+    @ExprAnn a = 1
+    @ExprAnn a += 1
+    return a
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/documented.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/documented.fir.kt
new file mode 100644
index 00000000000..6b97984be50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/documented.fir.kt
@@ -0,0 +1,8 @@
+@MustBeDocumented
+annotation class DocAnn
+
+annotation class NotDocAnn
+
+@DocAnn class My
+
+@NotDocAnn class Your
diff --git a/compiler/testData/diagnostics/tests/annotations/options/forParam.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/forParam.fir.kt
new file mode 100644
index 00000000000..f4416823d77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/forParam.fir.kt
@@ -0,0 +1,10 @@
+// See KT-9145
+
+@Target(AnnotationTarget.CLASS)
+annotation class Ann
+
+fun foo() {
+    for (@Ann private x in 1..100) {
+        if (x == 1) return
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/functionExpression.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/functionExpression.fir.kt
new file mode 100644
index 00000000000..7bd5906366e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/functionExpression.fir.kt
@@ -0,0 +1,12 @@
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class ExprAnn
+
+@Target(AnnotationTarget.FUNCTION)
+annotation class FunAnn
+
+fun foo(): Int {
+    val x = @ExprAnn fun() = 1
+    val y = @FunAnn fun() = 2
+    return x() + y()    
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/functions.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/functions.fir.kt
new file mode 100644
index 00000000000..e1caca0c43e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/functions.fir.kt
@@ -0,0 +1,40 @@
+// !WITH_NEW_INFERENCE
+@Target(AnnotationTarget.FUNCTION)
+annotation class FunAnn
+
+@Target(AnnotationTarget.FUNCTION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class SourceAnn
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class ExprAnn
+
+fun bar(arg: () -> Int) = arg()
+
+inline fun fast(arg: () -> Int) = arg()
+
+inline fun fast2(x: Int, arg: () -> Int) = x + arg()
+
+@FunAnn fun gav() = 13
+
+fun foo(arg: Int) {
+    // Literal is annotatable
+    bar @FunAnn { arg }
+    // Annotatable in principle but useless, fast is inline
+    fast @FunAnn { arg }
+    fast2(1, @FunAnn { arg })
+    // Source annotation, ok
+    fast @SourceAnn { arg }
+    fast2(1, @SourceAnn { arg })
+    // Expression annotation, ok
+    fast @ExprAnn { arg }
+    fast2(1, @ExprAnn { arg })
+    // Function expression too
+    val f = @FunAnn fun(): Int { return 42 }
+    // But here, f and gav should be annotated instead
+    bar(@FunAnn f)
+    bar(@FunAnn ::gav)
+    // Function expression, ok
+    fast(f)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/javaDocumented.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/javaDocumented.fir.kt
new file mode 100644
index 00000000000..3c50e6cf83b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/javaDocumented.fir.kt
@@ -0,0 +1,20 @@
+// FILE: DocumentedAnnotations.java
+
+import java.lang.annotation.*;
+
+public class DocumentedAnnotations {
+
+    @Documented public @interface DocAnn {};
+
+    public @interface NotDocAnn {};
+
+    @Documented @Retention(RetentionPolicy.RUNTIME) public @interface RunDocAnn {};
+}
+
+// FILE: DocumentedAnnotations.kt
+
+@DocumentedAnnotations.DocAnn class My
+
+@DocumentedAnnotations.NotDocAnn class Your
+
+@DocumentedAnnotations.RunDocAnn class His
diff --git a/compiler/testData/diagnostics/tests/annotations/options/javaKotlinTargetRetention.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/javaKotlinTargetRetention.fir.kt
new file mode 100644
index 00000000000..878fb7ad602
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/javaKotlinTargetRetention.fir.kt
@@ -0,0 +1,9 @@
+import java.lang.annotation.*
+
+@java.lang.annotation.Target(ElementType.PACKAGE)
+@Target(AnnotationTarget.CLASS)
+annotation class my
+
+@java.lang.annotation.Retention(RetentionPolicy.SOURCE)
+@Retention(AnnotationRetention.BINARY)
+annotation class your
diff --git a/compiler/testData/diagnostics/tests/annotations/options/javaretention.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/javaretention.fir.kt
new file mode 100644
index 00000000000..9da8584e996
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/javaretention.fir.kt
@@ -0,0 +1,35 @@
+// FILE: AnnotationRetentions.java
+
+import java.lang.annotation.*;
+
+public class AnnotationRetentions {
+
+    public @interface BaseAnnotation {
+
+    }
+
+    @Retention(RetentionPolicy.SOURCE)
+    public @interface SourceAnnotation {
+
+    }
+
+    @Retention(RetentionPolicy.CLASS)
+    public @interface BinaryAnnotation {
+
+    }
+
+    @Retention(RetentionPolicy.RUNTIME)
+    public @interface RuntimeAnnotation {
+
+    }
+}
+
+// FILE: AnnotationRetentions.kt
+
+@AnnotationRetentions.BaseAnnotation class BaseClass
+
+@AnnotationRetentions.SourceAnnotation class SourceClass
+
+@AnnotationRetentions.BinaryAnnotation class BinaryClass
+
+@AnnotationRetentions.RuntimeAnnotation class RuntimeClass
diff --git a/compiler/testData/diagnostics/tests/annotations/options/multiDeclaration.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/multiDeclaration.fir.kt
new file mode 100644
index 00000000000..80ffcfcb864
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/multiDeclaration.fir.kt
@@ -0,0 +1,7 @@
+@Target(AnnotationTarget.CLASS)
+annotation class My
+data class Pair(val a: Int, val b: Int)
+fun foo(): Int {
+    val (@My private a, @My public b) = Pair(12, 34)
+    return a + b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/objectLiteral.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/objectLiteral.fir.kt
new file mode 100644
index 00000000000..4f9a6d917c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/objectLiteral.fir.kt
@@ -0,0 +1,8 @@
+@Target(AnnotationTarget.CLASS)
+annotation class Ann
+
+open class My
+
+fun foo(): My {
+    return (@Ann object: My() {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/prefix.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/prefix.fir.kt
new file mode 100644
index 00000000000..8eb29e09ae3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/prefix.fir.kt
@@ -0,0 +1,13 @@
+@Target(AnnotationTarget.FUNCTION)
+annotation class FunAnn
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class ExprAnn
+
+fun foo(): Int {
+    var x = 5
+    @FunAnn ++x
+    @ExprAnn ++x
+    return x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/repeatable.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/repeatable.fir.kt
new file mode 100644
index 00000000000..1b3c23a9272
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/repeatable.fir.kt
@@ -0,0 +1,31 @@
+@Repeatable
+annotation class repann
+
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class repann1(val x: Int)
+
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class repann2(val f: Boolean)
+
+@Retention(AnnotationRetention.BINARY)
+@Repeatable
+annotation class binrepann
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class repexpr
+
+@repann @repann class DoubleAnnotated
+
+@repann1(1) @repann1(2) @repann1(3) class TripleAnnotated
+
+@repann2(true) @repann2(false) @repann2(false) @repann2(true) class FourTimesAnnotated
+
+@binrepann @binrepann class BinaryAnnotated
+
+@repann @repann fun foo(@repann @repann x: Int): Int {
+    @repexpr @repexpr return x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/retention.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/retention.fir.kt
new file mode 100644
index 00000000000..2ea2d384d69
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/retention.fir.kt
@@ -0,0 +1,4 @@
+@Retention(AnnotationRetention.SOURCE)
+annotation class sourceann
+
+@sourceann class AnnotatedAtSource
diff --git a/compiler/testData/diagnostics/tests/annotations/options/setterParam.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/setterParam.fir.kt
new file mode 100644
index 00000000000..89d774979d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/setterParam.fir.kt
@@ -0,0 +1,8 @@
+// KT-9145
+
+@Target(AnnotationTarget.CLASS)
+annotation class Ann
+
+var x: Int
+    get() = 1
+    set(@Ann private x) { }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/target.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/target.fir.kt
new file mode 100644
index 00000000000..107ff9bb57f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/target.fir.kt
@@ -0,0 +1,4 @@
+@Target(AnnotationTarget.CLASS)
+annotation class base
+
+@base data class My(val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/accessors.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/accessors.fir.kt
new file mode 100644
index 00000000000..47f5a243a6e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/accessors.fir.kt
@@ -0,0 +1,16 @@
+@Target(AnnotationTarget.PROPERTY_GETTER)
+annotation class smartget
+
+@Target(AnnotationTarget.PROPERTY_SETTER)
+annotation class smartset
+
+@Target(AnnotationTarget.FUNCTION)
+annotation class base
+
+class My(x: Int) {
+    @smartget var y = x
+    @base @smartget @smartset get
+    @base @smartget @smartset set
+
+    @base @smartget @smartset fun foo() = y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/annotation.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/annotation.fir.kt
new file mode 100644
index 00000000000..31b8e95d177
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/annotation.fir.kt
@@ -0,0 +1,20 @@
+@Target(AnnotationTarget.ANNOTATION_CLASS) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: Int) {
+    @base constructor(): this(0)
+}
+
+@base enum class My {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/classifier.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/classifier.fir.kt
new file mode 100644
index 00000000000..fc66e1f59ce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/classifier.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Target(AnnotationTarget.CLASS) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: Int, @base w: @base Int) {
+    @base constructor(): this(0, 0)
+}
+
+@base enum class My @base constructor() {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/constructor.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/constructor.fir.kt
new file mode 100644
index 00000000000..294579bda78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/constructor.fir.kt
@@ -0,0 +1,20 @@
+@Target(AnnotationTarget.CONSTRUCTOR) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: Int) {
+    @base constructor(): this(0)
+}
+
+@base enum class My @base constructor() {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/empty.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/empty.fir.kt
new file mode 100644
index 00000000000..19674e7f39b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/empty.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Target() annotation class empty
+
+@empty annotation class derived
+
+@empty class correct(@empty val x: Int, @empty w: @empty Int) {
+    @empty constructor(): this(0, 0)
+}
+
+@empty enum class My @empty constructor() {
+    @empty FIRST,
+    @empty SECOND
+}
+
+@empty fun foo(@empty y: @empty Int): Int {
+    @empty fun bar(@empty z: @empty Int) = z + 1
+    @empty val local = bar(y)
+    return local
+}
+
+@empty val z = @empty 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/expr.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/expr.fir.kt
new file mode 100644
index 00000000000..0c3f82d9278
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/expr.fir.kt
@@ -0,0 +1,13 @@
+annotation class base
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class special
+
+fun transform(i: Int, tr: (Int) -> Int): Int = @base @special tr(@special i)
+
+@base @special fun foo(i: Int): Int {
+    val j = @base @special i + 1
+    if (j == 1) return foo(@special @base 42)
+    return transform(@special j, @base @special { @special it * 2 })
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/field.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/field.fir.kt
new file mode 100644
index 00000000000..c1a3bdc1a65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/field.fir.kt
@@ -0,0 +1,45 @@
+// !WITH_NEW_INFERENCE
+@Target(AnnotationTarget.FIELD) 
+annotation class Field
+
+@Field
+annotation class Another
+
+@Field
+val x: Int = 42
+
+@Field
+val y: Int
+    get() = 13
+
+@Field
+abstract class My(@Field arg: Int, @Field val w: Int) {
+    @Field
+    val x: Int = arg
+
+    @Field
+    val y: Int
+        get() = 0
+
+    @Field
+    abstract val z: Int
+
+    @Field
+    fun foo() {}
+
+    @Field
+    val v: Int by <!UNRESOLVED_REFERENCE!>Delegates<!>.<!UNRESOLVED_REFERENCE!>lazy<!> { 42 }
+}
+
+enum class Your {
+    @Field FIRST
+}
+
+interface His {
+    @Field
+    val x: Int
+
+    @Field
+    val y: Int
+        get() = 42
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/file.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/file.fir.kt
new file mode 100644
index 00000000000..fff4469146c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/file.fir.kt
@@ -0,0 +1,23 @@
+// FILE: annotation.kt
+
+package test
+
+@Target(AnnotationTarget.FILE) annotation class special
+
+annotation class common
+
+// FILE: other.kt
+
+@file:special
+
+package test
+
+@special class Incorrect
+
+// FILE: another.kt
+
+@file:common
+
+package test
+
+@common class Correct
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/function.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/function.fir.kt
new file mode 100644
index 00000000000..e64693a83d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/function.fir.kt
@@ -0,0 +1,22 @@
+@Target(AnnotationTarget.FUNCTION) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: Int) {
+    @base constructor(): this(0)
+
+    @base public fun baz() {}
+}
+
+@base enum class My @base constructor() {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/funtypeargs.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/funtypeargs.fir.kt
new file mode 100644
index 00000000000..5374da7895c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/funtypeargs.fir.kt
@@ -0,0 +1,14 @@
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class special
+
+@Target(AnnotationTarget.TYPE)
+annotation class base
+
+fun transform(i: Int, tr: (@special Int) -> Int): Int = @special tr(@special i)
+
+fun foo(i: Int): Int {
+    val j = @special i + 1
+    if (j == 1) return foo(@special 42)
+    return transform(@special j, @special { i: @base Int -> @base i * 2 })
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/incorrect.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/incorrect.fir.kt
new file mode 100644
index 00000000000..fe4219516fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/incorrect.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Target(AnnotationTarget.<!UNRESOLVED_REFERENCE!>INIT<!>) annotation class incorrect
+
+@incorrect annotation class derived
+
+@incorrect class correct(@incorrect val x: Int, @incorrect w: @incorrect Int) {
+    @incorrect constructor(): this(0, 0)
+}
+
+@incorrect enum class My @incorrect constructor() {
+    @incorrect FIRST,
+    @incorrect SECOND
+}
+
+@incorrect fun foo(@incorrect y: @incorrect Int): Int {
+    @incorrect fun bar(@incorrect z: @incorrect Int) = z + 1
+    @incorrect val local = bar(y)
+    return local
+}
+
+@incorrect val z = @incorrect 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/init.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/init.fir.kt
new file mode 100644
index 00000000000..b69a5251d59
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/init.fir.kt
@@ -0,0 +1,6 @@
+annotation class base
+
+@base class My {
+    @base init {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/java.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/java.fir.kt
new file mode 100644
index 00000000000..7d9b683f27e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/java.fir.kt
@@ -0,0 +1,82 @@
+// FILE: test/AnnotationTargets.java
+
+package test;
+
+import java.lang.annotation.*;
+
+public class AnnotationTargets {
+
+    public @interface base {
+
+    }
+
+    @Target(ElementType.ANNOTATION_TYPE)
+    public @interface meta {
+
+    }
+
+    @Target(ElementType.CONSTRUCTOR)
+    public @interface konstructor {
+
+    }
+
+    @Target(ElementType.FIELD)
+    public @interface fieldann {
+
+    }
+
+
+    @Target(ElementType.LOCAL_VARIABLE)
+    public @interface local {
+
+    }
+
+    @Target(ElementType.METHOD)
+    public @interface method {
+
+    }
+
+    @Target(ElementType.PARAMETER)
+    public @interface parameter {
+
+    }
+
+
+    @Target(ElementType.TYPE)
+    public @interface type {
+
+    }
+
+    @Target({ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.FIELD})
+    public @interface multiple {
+
+    }
+}
+
+// FILE: test/AnnotationTargets.kt
+
+@file:AnnotationTargets.type
+package test
+
+import test.AnnotationTargets.*
+
+@base @meta @type @konstructor annotation class KMeta
+
+@base @meta @type @method @multiple class KClass(
+        @base @fieldann @parameter val y:
+        @base @type Int) {
+
+    @base @multiple @fieldann @local val x = 0
+    @method @konstructor @type get
+
+    @base @method @multiple @konstructor
+    fun foo(@parameter @type i:
+    @base @multiple Int
+    ): @fieldann @parameter Int {
+
+        @local @base @multiple @fieldann val j = i + 1
+        @base @multiple return j
+    }
+
+    @base @method @konstructor constructor(): this(0)
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/local.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/local.fir.kt
new file mode 100644
index 00000000000..a3b51770c7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/local.fir.kt
@@ -0,0 +1,20 @@
+@Target(AnnotationTarget.LOCAL_VARIABLE) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: Int) {
+    @base constructor(): this(0)
+}
+
+@base enum class My {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/nested.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/nested.fir.kt
new file mode 100644
index 00000000000..a836dd98491
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/nested.fir.kt
@@ -0,0 +1,15 @@
+@Target(AnnotationTarget.CLASS)
+annotation class base
+
+@Target(AnnotationTarget.ANNOTATION_CLASS)
+annotation class meta
+
+@base class Outer {
+    @base @meta class Nested
+
+    @base @meta annotation class Annotated
+
+    fun foo() {
+        @base @meta class Local
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/property.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/property.fir.kt
new file mode 100644
index 00000000000..73fe69e8cda
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/property.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Target(AnnotationTarget.PROPERTY) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: Int, @base w: Int) {
+    @base constructor(): this(0, 0)
+}
+
+@base enum class My {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/returntype.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/returntype.fir.kt
new file mode 100644
index 00000000000..fc73f675e77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/returntype.fir.kt
@@ -0,0 +1,9 @@
+annotation class base
+
+@Target(AnnotationTarget.TYPE)
+annotation class typed
+
+@base class My(val x: @base @typed Int, y: @base @typed Int) {
+    val z: @base @typed Int = y
+    fun foo(): @base @typed Int = z
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/suppress.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/suppress.fir.kt
new file mode 100644
index 00000000000..a2bcb5cb48c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/suppress.fir.kt
@@ -0,0 +1,5 @@
+@file:Suppress("abc")
+
+fun foo(): Int {
+    @Suppress("xyz") return 1
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/type.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/type.fir.kt
new file mode 100644
index 00000000000..fddebafe484
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/type.fir.kt
@@ -0,0 +1,20 @@
+@Target(AnnotationTarget.TYPE) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: @base Int) {
+    @base constructor(): this(0)
+}
+
+@base enum class My @base constructor() {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/typeParams.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/typeParams.fir.kt
new file mode 100644
index 00000000000..bb4af67b25c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/typeParams.fir.kt
@@ -0,0 +1,38 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER
+
+@Target(AnnotationTarget.TYPE_PARAMETER)
+annotation class A
+
+@Target(AnnotationTarget.TYPE_PARAMETER)
+annotation class B(val i: Int = 12)
+
+
+fun <@A @B(3) T> topFun() = 12
+
+class Class1 {
+    fun <@A @B(3)T> method() = 12
+
+    fun foo() {
+        fun <@A @B(3) T> innerFun() = 12
+    }
+}
+
+val <@A @B(3) T> T.topProp: Int get() = 12
+
+class Class2 {
+    val <@A @B(3) T> T.field: Int get() = 12
+}
+
+
+@A fun foo() {}
+@A class D
+fun foo(i: @A Int) {
+    @A val i = 1
+}
+fun <T> test(t: @A T): T = t
+
+
+@Target(AnnotationTarget.TYPE)
+internal annotation class C
+
+fun <@C T> test2(t: T): T = t
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/typeargs.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/typeargs.fir.kt
new file mode 100644
index 00000000000..0ac291e9e92
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/typeargs.fir.kt
@@ -0,0 +1,10 @@
+annotation class base
+
+val x: List<@base String>? = null
+
+val y: List<@[base] String>? = null
+
+@Target(AnnotationTarget.TYPE)
+annotation class typeAnn
+
+fun foo(list: List<@typeAnn Int>) = list
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/options/targets/valueparam.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/targets/valueparam.fir.kt
new file mode 100644
index 00000000000..89f1de3c26d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/targets/valueparam.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Target(AnnotationTarget.VALUE_PARAMETER) annotation class base
+
+@base annotation class derived
+
+@base class correct(@base val x: Int, @base w: Int) {
+    @base constructor(): this(0, 0)
+}
+
+@base enum class My {
+    @base FIRST,
+    @base SECOND
+}
+
+@base fun foo(@base y: @base Int): Int {
+    @base fun bar(@base z: @base Int) = z + 1
+    @base val local = bar(y)
+    return local
+}
+
+@base val z = 0
diff --git a/compiler/testData/diagnostics/tests/annotations/options/unrepeatable.fir.kt b/compiler/testData/diagnostics/tests/annotations/options/unrepeatable.fir.kt
new file mode 100644
index 00000000000..ea3e981f159
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/options/unrepeatable.fir.kt
@@ -0,0 +1,23 @@
+annotation class unrepann(val x: Int)
+
+annotation class ann(val y: Int)
+
+@unrepann(1) @unrepann(2) class DoubleAnnotated
+
+@ann(3) @ann(7) @ann(42) class TripleAnnotated
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class annexpr
+
+@ann(0) @ann(1) fun foo(@ann(7) @ann(2) x: Int): Int {
+    @annexpr @annexpr return x
+}
+
+@unrepann(0)
+@get:unrepann(1)
+var annotated = 1 // No errors should be here
+
+@unrepann(0)
+@property:unrepann(1)
+var annotated2 = 2
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/cannotOverrideInvisibleMember.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/cannotOverrideInvisibleMember.fir.kt
new file mode 100644
index 00000000000..ae412ba8eb7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/cannotOverrideInvisibleMember.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -INCOMPATIBLE_MODIFIERS
+// !RENDER_DIAGNOSTICS_MESSAGES
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS)
+annotation class A
+
+@A
+open class B1 {
+    @A
+    private open fun foo() {}
+}
+
+class D1 : B1() {
+    override fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/conflictingOverloads.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/conflictingOverloads.fir.kt
new file mode 100644
index 00000000000..fdd2776bba6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/conflictingOverloads.fir.kt
@@ -0,0 +1,10 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS,  AnnotationTarget.PROPERTY,  AnnotationTarget.VALUE_PARAMETER)
+annotation class An
+
+@An
+data class A(@An val x: @An Int) {
+    @An
+    fun copy(@An x: @An Int) = x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/differentNamesForParameter.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/differentNamesForParameter.fir.kt
new file mode 100644
index 00000000000..322233012fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/differentNamesForParameter.fir.kt
@@ -0,0 +1,18 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS,  AnnotationTarget.PROPERTY,  AnnotationTarget.VALUE_PARAMETER)
+annotation class An
+
+@An
+interface A {
+    @An
+    fun foo(@An a : @An Int)
+}
+
+@An
+interface B {
+    @An
+    fun foo(@An b : @An Int)
+}
+
+interface C : A, B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/memberProjectedOut.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/memberProjectedOut.fir.kt
new file mode 100644
index 00000000000..fbbaba7fb47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/memberProjectedOut.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+// !RENDER_DIAGNOSTICS_MESSAGES
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS)
+annotation class A
+
+@A
+class C<T> {
+    @A
+    operator fun set(x: @A Int, y: @A T) {}
+}
+
+fun test(a: C<out CharSequence>) {
+    <!INAPPLICABLE_CANDIDATE!>a[1] = 25<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/multipleInheritedDefaults.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/multipleInheritedDefaults.fir.kt
new file mode 100644
index 00000000000..646f648ff0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/multipleInheritedDefaults.fir.kt
@@ -0,0 +1,26 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+// !DIAGNOSTICS: -ABSTRACT_MEMBER_NOT_IMPLEMENTED
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS,  AnnotationTarget.VALUE_PARAMETER,  AnnotationTarget.PROPERTY,  AnnotationTarget.EXPRESSION)
+@Retention( AnnotationRetention.SOURCE)
+annotation class An
+
+@An
+interface A {
+    @An
+    fun foo(@An a: @An Int = @An 1)
+}
+
+@An
+interface B {
+    @An
+    fun foo(@An a: @An Int = @An 2)
+}
+
+class AB1 : A, B
+
+@An
+class AB2 : A, B {
+    @An
+    override fun foo(@An a: @An Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/notImplementedMembers.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/notImplementedMembers.fir.kt
new file mode 100644
index 00000000000..081c2838d5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/notImplementedMembers.fir.kt
@@ -0,0 +1,48 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS,  AnnotationTarget.VALUE_PARAMETER,  AnnotationTarget.PROPERTY)
+annotation class An
+
+@An
+interface A {
+    @An
+    fun a(@An arg: @An Int)
+}
+
+@An
+interface B {
+    @An
+    fun <T> a(@An arg: @An Int)
+}
+
+interface C : A, B
+
+@An
+abstract class D {
+    @An
+    abstract val d: @An Int
+}
+
+class E : D(), A
+class F : A
+
+@An
+interface G {
+    @An
+    fun a(@An arg: @An Int)
+}
+
+@An
+interface AI : A {
+    @An
+    override fun a(@An arg: @An Int) {}
+}
+
+@An
+interface GI : G {
+    @An
+    override fun a(@An arg: @An Int) {}
+}
+
+class AG1(val a: A, val g: G) : A by a, G by g
+class AG2() : AI, GI
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/tooManyArguments.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/tooManyArguments.fir.kt
new file mode 100644
index 00000000000..b59d761bfba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/tooManyArguments.fir.kt
@@ -0,0 +1,11 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS)
+annotation class Ann(val s: String = "")
+
+@Ann("s")
+fun foo() {}
+
+val bar = <!INAPPLICABLE_CANDIDATE!>foo<!>(
+    15
+)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchDueToTypeProjections.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchDueToTypeProjections.fir.kt
new file mode 100644
index 00000000000..79b90d1f64c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchDueToTypeProjections.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !RENDER_DIAGNOSTICS_MESSAGES
+// !WITH_NEW_INFERENCE
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS)
+annotation class A
+
+@A
+class C<T> {
+    @A
+    operator fun plus(x: Out<@A T>): @A C<@A T> = this
+}
+
+class Out<out F>
+
+fun test(a: C<out CharSequence>, y: Out<CharSequence>) {
+    a + y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchOnOverride.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchOnOverride.fir.kt
new file mode 100644
index 00000000000..2a3d5566e23
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchOnOverride.fir.kt
@@ -0,0 +1,26 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS,  AnnotationTarget.PROPERTY,  AnnotationTarget.VALUE_PARAMETER)
+annotation class An
+
+@An
+interface A {
+    @An
+    val p1: @An String
+    @An
+    var p2: @An String
+    @An
+    fun test(@An arg: @An String): @An String
+}
+
+@An
+interface B : A {
+    override val p1: Int
+    @An
+    override val p2: @An String
+    override fun test(arg: String): Int
+}
+
+interface C : A {
+    override var p2: Int
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchOnOverrideJavaNullable.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchOnOverrideJavaNullable.fir.kt
new file mode 100644
index 00000000000..e34b5de84f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/typeMismatchOnOverrideJavaNullable.fir.kt
@@ -0,0 +1,42 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+// JAVAC_SKIP
+
+// FILE: A.java
+
+import org.jetbrains.annotations.NotNull;
+import java.lang.annotation.*;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+@javax.annotation.meta.TypeQualifier
+public @interface MyTypeQualifier {}
+
+@An
+public interface A {
+    @NotNull
+    @An
+    @MyTypeQualifier
+    String foo();
+}
+
+// FILE: k.kt
+
+import org.jetbrains.annotations.NotNull;
+
+@Target(AnnotationTarget.FUNCTION, AnnotationTarget.TYPE, AnnotationTarget.CLASS,  AnnotationTarget.PROPERTY,  AnnotationTarget.VALUE_PARAMETER)
+annotation class An
+
+class B : A {
+    override fun foo(): String? = null
+}
+
+@An
+public interface C {
+    @NotNull
+    @An
+    fun foo(): String
+}
+
+class D : C {
+    override fun foo(): String? = null
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/rendering/unusedValue.fir.kt b/compiler/testData/diagnostics/tests/annotations/rendering/unusedValue.fir.kt
new file mode 100644
index 00000000000..42e57965221
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/rendering/unusedValue.fir.kt
@@ -0,0 +1,12 @@
+// !RENDER_DIAGNOSTICS_MESSAGES
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+
+@Target(AnnotationTarget.PROPERTY,  AnnotationTarget.FUNCTION, AnnotationTarget.TYPE,  AnnotationTarget.LOCAL_VARIABLE)
+annotation class A
+
+@A
+fun test() {
+    @A
+    var b: @A Int = 0
+    b = 15
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/typeAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/typeAnnotations.fir.kt
new file mode 100644
index 00000000000..d0e22f7c574
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/typeAnnotations.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+class A
+
+@Target(AnnotationTarget.TYPE)
+annotation class x
+
+fun @x A.foo(a: @x Int) {
+    val v: @x Int = 1
+}
+
+fun <T> @x List<@x T>.foo(l: List<@x T>): @x List<@x T> = throw Exception()
+
+fun <T, U: T> List<@x T>.firstTyped(): U = throw Exception()
+
+val <T> @x List<@x T>.f: Int get() = 42
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/typeParameterAsAnnotation.fir.kt b/compiler/testData/diagnostics/tests/annotations/typeParameterAsAnnotation.fir.kt
new file mode 100644
index 00000000000..cedd6de950f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/typeParameterAsAnnotation.fir.kt
@@ -0,0 +1,9 @@
+class Foo<T> {
+    @T
+    fun foo() = 0
+}
+
+class Bar<T : Annotation> {
+    @T
+    fun foo() = 0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/unresolvedReferenceRange.fir.kt b/compiler/testData/diagnostics/tests/annotations/unresolvedReferenceRange.fir.kt
new file mode 100644
index 00000000000..9ef01c335a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/unresolvedReferenceRange.fir.kt
@@ -0,0 +1,5 @@
+@Ann class A
+@Ann class B
+@Ann(1) class C
+@kotlin.Ann(1) class D
+@kotlin.annotation.Ann(1) class E
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/DelegateAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/DelegateAnnotations.fir.kt
new file mode 100644
index 00000000000..930f962015f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/DelegateAnnotations.fir.kt
@@ -0,0 +1,33 @@
+import kotlin.reflect.KProperty
+
+@Target(AnnotationTarget.FIELD) annotation class Field
+
+@Target(AnnotationTarget.PROPERTY) annotation class Prop
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+}
+
+@delegate:Field
+class SomeClass {
+
+    @delegate:Field
+    constructor()
+
+    @delegate:Field @delegate:Prop
+    protected val simpleProperty: String = "text"
+
+    @delegate:Field @delegate:Prop
+    protected val delegatedProperty: String by CustomDelegate()
+
+    @delegate:Field @delegate:Prop
+    val propertyWithCustomGetter: Int
+        get() = 5
+
+}
+
+class WithPrimaryConstructor(@delegate:Field @delegate:Prop val a: String,
+                             @param:Field @param:Prop val b: String)
+
+fun foo(@delegate:Field @delegate:Prop x: Int) = x
+
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/FieldAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/FieldAnnotations.fir.kt
new file mode 100644
index 00000000000..006381feb39
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/FieldAnnotations.fir.kt
@@ -0,0 +1,36 @@
+import kotlin.reflect.KProperty
+
+annotation class Ann
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+}
+
+@field:Ann
+class SomeClass {
+
+    @field:Ann
+    constructor()
+
+    @field:Ann
+    protected val simpleProperty: String = "text"
+
+    @field:[Ann]
+    protected val simplePropertyWithAnnotationList: String = "text"
+
+    @field:Ann
+    protected val delegatedProperty: String by CustomDelegate()
+
+    @field:Ann
+    val propertyWithCustomGetter: Int
+        get() = 5
+
+    @field:Ann
+    fun anotherFun(@field:Ann s: String) {
+        @field:Ann
+        val localVariable = 5
+    }
+
+}
+
+class WithPrimaryConstructor(@field:Ann val a: String)
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/FileAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/FileAnnotations.fir.kt
new file mode 100644
index 00000000000..1092884e7f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/FileAnnotations.fir.kt
@@ -0,0 +1,12 @@
+// FILE: annotations.kt
+@Target(AnnotationTarget.CLASS)
+public annotation class ClassAnn
+
+@Target(AnnotationTarget.FILE)
+public annotation class FileAnn
+
+// FILE: 1.kt
+@file:ClassAnn
+
+// FILE: 2.kt
+@file:FileAnn
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/GetterAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/GetterAnnotations.fir.kt
new file mode 100644
index 00000000000..343a6ccde0d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/GetterAnnotations.fir.kt
@@ -0,0 +1,39 @@
+import kotlin.reflect.KProperty
+
+annotation class Ann
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+}
+
+@get:Ann
+class SomeClass {
+
+    @get:Ann
+    constructor()
+
+    @get:Ann
+    protected val simpleProperty: String = "text"
+
+    @get:Ann
+    protected var mutableProperty: String = "text"
+
+    @get:[Ann]
+    protected val simplePropertyWithAnnotationList: String = "text"
+
+    @get:Ann
+    protected val delegatedProperty: String by CustomDelegate()
+
+    @get:Ann
+    val propertyWithCustomGetter: Int
+        get() = 5
+
+    @get:Ann
+    fun annotationOnFunction(a: Int) = a + 5
+
+    fun anotherFun() {
+        @get:Ann
+        val localVariable = 5
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/ParamAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/ParamAnnotations.fir.kt
new file mode 100644
index 00000000000..f0f7b9c9442
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/ParamAnnotations.fir.kt
@@ -0,0 +1,24 @@
+annotation class Ann
+annotation class Second
+
+@param:Ann
+class SomeClass {
+
+    @param:Ann
+    constructor(@param:Ann a: String)
+
+    @param:Ann
+    protected val simpleProperty: String = "text"
+
+    @param:Ann
+    fun anotherFun() {
+        @param:Ann
+        val localVariable = 5
+    }
+
+}
+
+class PrimaryConstructorClass(
+        @param:Ann a: String,
+@param:[Ann Second] b: String,
+@param:Ann val c: String)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/PropertyAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/PropertyAnnotations.fir.kt
new file mode 100644
index 00000000000..9142c89dbb6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/PropertyAnnotations.fir.kt
@@ -0,0 +1,39 @@
+import kotlin.reflect.KProperty
+
+annotation class Ann
+annotation class Second
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+}
+
+@property:Ann
+class SomeClass {
+
+    @property:Ann
+    constructor(s: String)
+
+    @property:Ann
+    protected val p1: String = ""
+
+    @property:[Ann Second]
+    protected val p2: String = ""
+
+    @property:Ann
+    protected var p3: String = ""
+
+    @property:Ann
+    protected val p4: String by CustomDelegate()
+
+    @property:Ann
+    var propertyWithCustomSetter: Int
+        get() = 5
+        set(v) {}
+
+    @property:Ann
+    fun anotherFun() {
+        @property:Ann
+        val localVariable = 5
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/ReceiverAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/ReceiverAnnotations.fir.kt
new file mode 100644
index 00000000000..74ccbb4be01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/ReceiverAnnotations.fir.kt
@@ -0,0 +1,25 @@
+annotation class Ann
+
+@receiver:Ann
+class SomeClass {
+
+    @receiver:Ann
+    constructor(@receiver:Ann a: String)
+
+    @receiver:Ann
+    protected val simpleProperty: String = "text"
+
+    @receiver:Ann
+    fun anotherFun() {
+        @receiver:Ann
+        val localVariable = 5
+    }
+
+    val @receiver:Ann String.extensionProperty2: String
+        get() = "A"
+}
+
+fun @receiver:Ann String.length2() = length
+
+val @receiver:Ann String.extensionProperty: String
+    get() = "A"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/SetterAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/SetterAnnotations.fir.kt
new file mode 100644
index 00000000000..ddde82164fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/SetterAnnotations.fir.kt
@@ -0,0 +1,38 @@
+import kotlin.reflect.KProperty
+
+annotation class Ann
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, value: String) {}
+}
+
+@set:Ann
+class SomeClass {
+
+    @set:Ann
+    protected val simpleProperty: String = "text"
+
+    @set:Ann
+    protected var mutableProperty: String = "text"
+
+    @set:[Ann]
+    protected var mutablePropertyWithAnnotationList: String = "text"
+
+    @set:Ann
+    protected var delegatedProperty: String by CustomDelegate()
+
+    @set:Ann
+    var propertyWithCustomSetter: Int
+        get() = 5
+        set(v) {}
+
+    @set:Ann
+    fun annotationOnFunction(a: Int) = a + 5
+
+    fun anotherFun() {
+        @set:Ann
+        val localVariable = 5
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/SparamAnnotations.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/SparamAnnotations.fir.kt
new file mode 100644
index 00000000000..9279aa0120a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/SparamAnnotations.fir.kt
@@ -0,0 +1,39 @@
+import kotlin.reflect.KProperty
+
+annotation class Ann
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, value: String) {}
+}
+
+@setparam:Ann
+class SomeClass {
+
+    @setparam:Ann
+    constructor()
+
+    @setparam:Ann
+    protected val simpleProperty: String = "text"
+
+    @setparam:Ann
+    protected var mutableProperty: String = "text"
+
+    @setparam:[Ann]
+    protected var mutablePropertyWithAnnotationList: String = "text"
+
+    @setparam:Ann
+    protected var delegatedProperty: String by CustomDelegate()
+
+    @setparam:Ann
+    var propertyWithCustomSetter: Int
+        get() = 5
+        set(v) {}
+
+    @setparam:Ann
+    fun anotherFun() {
+        @setparam:Ann
+        val localVariable = 5
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticFileAnnotationInWrongPlace.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticFileAnnotationInWrongPlace.fir.kt
new file mode 100644
index 00000000000..91147c0b82d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticFileAnnotationInWrongPlace.fir.kt
@@ -0,0 +1,20 @@
+package bar
+
+@file:foo
+val prop
+
+@file:[bar baz]
+fun func() {}
+
+@file:[baz]
+class C
+
+<!SYNTAX!>@file:<!>
+interface T
+
+@file:[<!SYNTAX!><!>]
+interface T
+
+annotation class foo
+annotation class bar
+annotation class baz
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticWithoutPackage.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticWithoutPackage.fir.kt
new file mode 100644
index 00000000000..026f57fa379
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticWithoutPackage.fir.kt
@@ -0,0 +1,8 @@
+@file:foo
+@foo @bar
+@file:[baz]
+fun test() {}
+
+annotation class foo
+annotation class bar
+annotation class baz
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticWithoutPackageWithSimpleAnnotation.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticWithoutPackageWithSimpleAnnotation.fir.kt
new file mode 100644
index 00000000000..ab22f55f577
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/diagnosticWithoutPackageWithSimpleAnnotation.fir.kt
@@ -0,0 +1,8 @@
+@file:foo
+@foo @bar
+@file: baz
+fun test() {}
+
+annotation class foo
+annotation class bar
+annotation class baz
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/fileAnnotationWithoutColon_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/fileAnnotationWithoutColon_after.fir.kt
new file mode 100644
index 00000000000..0ea7436b026
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/fileAnnotationWithoutColon_after.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +RestrictionOfWrongAnnotationsWithUseSiteTargetsOnTypes
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test1(@file<!SYNTAX!><!> Suppress("") x: Int) {}
+
+@file <!SYNTAX!>@<!>Suppress("")
+fun test2() {}
+
+class OnType(x: @file<!SYNTAX!><!> Suppress("") Int)
+
+fun @file : Suppress("") Int.test3() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/fileAnnotationWithoutColon_before.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/fileAnnotationWithoutColon_before.fir.kt
new file mode 100644
index 00000000000..b67f6f53f0c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/fileAnnotationWithoutColon_before.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: -RestrictionOfWrongAnnotationsWithUseSiteTargetsOnTypes
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test1(@file<!SYNTAX!><!> Suppress("") x: Int) {}
+
+@file <!SYNTAX!>@<!>Suppress("")
+fun test2() {}
+
+class OnType(x: @file<!SYNTAX!><!> Suppress("") Int)
+
+fun @file : Suppress("") Int.test3() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt23992.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt23992.fir.kt
new file mode 100644
index 00000000000..2164ebed7f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt23992.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: -ProhibitUseSiteTargetAnnotationsOnSuperTypes
+
+interface Foo
+
+annotation class Ann
+
+class E : @field:Ann @get:Ann @set:Ann @setparam:Ann Foo
+
+interface G : @Ann Foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt23992_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt23992_after.fir.kt
new file mode 100644
index 00000000000..d85a79c1c5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt23992_after.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +ProhibitUseSiteTargetAnnotationsOnSuperTypes
+
+interface Foo
+
+annotation class Ann
+
+class E : @field:Ann @get:Ann @set:Ann @setparam:Ann Foo
+
+interface G : @Ann Foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt26638.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt26638.fir.kt
new file mode 100644
index 00000000000..e9e29f0434f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt26638.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !LANGUAGE: -ProhibitRepeatedUseSiteTargetAnnotations
+
+// Ann is not repeatable
+annotation class Ann(val x: Int)
+
+@get:Ann(10)
+val a: String
+    @Ann(20) get() = "foo"
+
+@set:Ann(10)
+var b: String = ""
+    @Ann(20) set(value) { field = value }
+
+@setparam:Ann(10)
+var c = " "
+    set(@Ann(20) x) {}
+
+@get:Ann(10)
+@get:Ann(20)
+val d: String
+    @Ann(30) @Ann(40) get() = "foo"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt26638_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt26638_after.fir.kt
new file mode 100644
index 00000000000..138bab0c129
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/kt26638_after.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !LANGUAGE: +ProhibitRepeatedUseSiteTargetAnnotations
+
+// Ann is not repeatable
+annotation class Ann(val x: Int)
+
+@get:Ann(10)
+val a: String
+    @Ann(20) get() = "foo"
+
+@set:Ann(10)
+var b: String = ""
+    @Ann(20) set(value) { field = value }
+
+@setparam:Ann(10)
+var c = " "
+    set(@Ann(20) x) {}
+
+@get:Ann(10)
+@get:Ann(20)
+val d: String
+    @Ann(30) @Ann(40) get() = "foo"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/receiverUseSiteTargetOnExtensionFunction_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/receiverUseSiteTargetOnExtensionFunction_after.fir.kt
new file mode 100644
index 00000000000..6fc63f57ceb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/receiverUseSiteTargetOnExtensionFunction_after.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +RestrictionOfWrongAnnotationsWithUseSiteTargetsOnTypes
+
+@Target(AnnotationTarget.VALUE_PARAMETER)
+annotation class Fancy
+
+fun @receiver:Fancy String.myExtension() { }
+val @receiver:Fancy Int.asVal get() = 0
+
+fun ((@receiver:Fancy Int) -> Unit).complexReceiver1() {}
+fun ((Int) -> @receiver:Fancy Unit).complexReceiver2() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/receiverUseSiteTargetOnExtensionFunction_before.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/receiverUseSiteTargetOnExtensionFunction_before.fir.kt
new file mode 100644
index 00000000000..e2ce398bcdc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/receiverUseSiteTargetOnExtensionFunction_before.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: -RestrictionOfWrongAnnotationsWithUseSiteTargetsOnTypes
+
+@Target(AnnotationTarget.VALUE_PARAMETER)
+annotation class Fancy
+
+fun @receiver:Fancy String.myExtension() { }
+val @receiver:Fancy Int.asVal get() = 0
+
+fun ((@receiver:Fancy Int) -> Unit).complexReceiver1() {}
+fun ((Int) -> @receiver:Fancy Unit).complexReceiver2() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/repeatable.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/repeatable.fir.kt
new file mode 100644
index 00000000000..bc12a82c794
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/repeatable.fir.kt
@@ -0,0 +1,59 @@
+import kotlin.reflect.KProperty
+
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class RepeatableAnn
+annotation class Ann
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+}
+
+public class A(@param:Ann @Ann val x: Int, @param: RepeatableAnn @Ann val y: Int) {
+
+    @field:Ann @property:Ann @RepeatableAnn @property:RepeatableAnn
+    val a: Int = 0
+
+    @Ann @field:Ann @property:Ann
+    val b: Int = 0
+
+    @field:RepeatableAnn @field:RepeatableAnn
+    val c: Int = 0
+
+    @property:RepeatableAnn @RepeatableAnn
+    val d: Int = 0
+
+    @property:RepeatableAnn @RepeatableAnn @delegate:RepeatableAnn
+    val e: String by CustomDelegate()
+
+    @property:Ann @delegate:Ann
+    val f: String by CustomDelegate()
+
+    @Ann @delegate:Ann
+    val g: String by CustomDelegate()
+
+    @Ann @field:Ann
+    val h: String = ""
+
+    @property:Ann @field:Ann
+    val i: String = ""
+}
+
+@Target(AnnotationTarget.FIELD, AnnotationTarget.PROPERTY)
+annotation class fieldOrPropAnn
+
+@Target(AnnotationTarget.PROPERTY_GETTER, AnnotationTarget.PROPERTY_SETTER, AnnotationTarget.VALUE_PARAMETER)
+annotation class getSetAndParamAnn
+
+public class B(@param:fieldOrPropAnn @fieldOrPropAnn val x: Int,
+               @property:fieldOrPropAnn @fieldOrPropAnn val y: Int) {
+    @fieldOrPropAnn @field:fieldOrPropAnn
+    val z: Int = 42
+
+    @getSetAndParamAnn
+    @setparam:getSetAndParamAnn
+    var w: Int
+        @getSetAndParamAnn @get:getSetAndParamAnn get() = 0
+        // See KT-15470: fake INAPPLICABLE_TARGET_ON_PROPERTY
+        @getSetAndParamAnn @set:getSetAndParamAnn set(arg) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypesError.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypesError.fir.kt
new file mode 100644
index 00000000000..ab1df1b5508
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypesError.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +RestrictionOfWrongAnnotationsWithUseSiteTargetsOnTypes
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test1(i: @setparam:Suppress Int) {}
+fun test2(i: @param:Suppress Int) {}
+fun test3(i: @receiver:Suppress Int) {}
+
+fun test4(): @setparam:Suppress Int = TODO()
+fun test5(i: (@setparam:Suppress Int) -> Unit) {}
+
+fun ((@setparam:Suppress Int) -> Unit).test6() {}
+
+fun test7(): ((@setparam:Suppress Int) -> Unit) = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypes_after.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypes_after.fir.kt
new file mode 100644
index 00000000000..ab1df1b5508
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypes_after.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +RestrictionOfWrongAnnotationsWithUseSiteTargetsOnTypes
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test1(i: @setparam:Suppress Int) {}
+fun test2(i: @param:Suppress Int) {}
+fun test3(i: @receiver:Suppress Int) {}
+
+fun test4(): @setparam:Suppress Int = TODO()
+fun test5(i: (@setparam:Suppress Int) -> Unit) {}
+
+fun ((@setparam:Suppress Int) -> Unit).test6() {}
+
+fun test7(): ((@setparam:Suppress Int) -> Unit) = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypes_before.fir.kt b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypes_before.fir.kt
new file mode 100644
index 00000000000..3b9eed6b1b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/annotations/withUseSiteTarget/wrongParamAnnotationsOnTypes_before.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: -RestrictionOfWrongAnnotationsWithUseSiteTargetsOnTypes
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test1(i: @setparam:Suppress Int) {}
+fun test2(i: @param:Suppress Int) {}
+fun test3(i: @receiver:Suppress Int) {}
+
+fun test4(): @setparam:Suppress Int = TODO()
+fun test5(i: (@setparam:Suppress Int) -> Unit) {}
+
+fun ((@setparam:Suppress Int) -> Unit).test6() {}
+
+fun test7(): ((@setparam:Suppress Int) -> Unit) = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/CustomGetSet.fir.kt b/compiler/testData/diagnostics/tests/backingField/CustomGetSet.fir.kt
new file mode 100644
index 00000000000..db201619dcb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/CustomGetSet.fir.kt
@@ -0,0 +1,6 @@
+class Flower() {
+
+    var minusOne: Int = 1
+        get() = field + 1
+        set(n: Int) { field = n - 1 }
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/CustomGetVal.fir.kt b/compiler/testData/diagnostics/tests/backingField/CustomGetVal.fir.kt
new file mode 100644
index 00000000000..383f29764d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/CustomGetVal.fir.kt
@@ -0,0 +1,4 @@
+class CustomGetVal() {
+    val zz = 1
+        get() = field * 2
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/CustomGetValGlobal.fir.kt b/compiler/testData/diagnostics/tests/backingField/CustomGetValGlobal.fir.kt
new file mode 100644
index 00000000000..c76eab0e2c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/CustomGetValGlobal.fir.kt
@@ -0,0 +1,3 @@
+package customGetValGlobal
+    val zz = 1
+        get() = field * 2
diff --git a/compiler/testData/diagnostics/tests/backingField/CustomGetVar.fir.kt b/compiler/testData/diagnostics/tests/backingField/CustomGetVar.fir.kt
new file mode 100644
index 00000000000..62aebd10741
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/CustomGetVar.fir.kt
@@ -0,0 +1,4 @@
+class Raise() {
+    var zz = 1
+        get() = field * 2
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/CustomSet.fir.kt b/compiler/testData/diagnostics/tests/backingField/CustomSet.fir.kt
new file mode 100644
index 00000000000..e2319e7505a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/CustomSet.fir.kt
@@ -0,0 +1,4 @@
+class Raise() {
+    var zz = 1
+        set(it) { field = it / 2 }
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/ExtensionProperty.fir.kt b/compiler/testData/diagnostics/tests/backingField/ExtensionProperty.fir.kt
new file mode 100644
index 00000000000..c66c6691dcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/ExtensionProperty.fir.kt
@@ -0,0 +1,17 @@
+// See KT-9303: synthetic field variable does not exist for extension properties
+val String.foo: Int
+    get() {
+        // No shadowing here
+        val field = 42
+        return field
+    }
+
+val String.bar: Int = 13
+    // Error
+    get() = field
+
+class My {
+    val String.x: Int = 7
+        // Error
+        get() = field
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldAsParam.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldAsParam.fir.kt
new file mode 100644
index 00000000000..33541e1b809
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldAsParam.fir.kt
@@ -0,0 +1,8 @@
+var y: Int = 1
+
+// No backing field!
+var x: Int
+    get() = y
+    set(field) {
+        y = field
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldAsProperty.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldAsProperty.fir.kt
new file mode 100644
index 00000000000..a0990d567d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldAsProperty.fir.kt
@@ -0,0 +1,9 @@
+class My(val field: Int) {
+    // Backing field, initializer
+    val second: Int = 0
+        get() = field
+
+    // No backing field, no initializer
+    val third: Int
+        get() = this.field
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldDerived.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldDerived.fir.kt
new file mode 100644
index 00000000000..02c7621e8ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldDerived.fir.kt
@@ -0,0 +1,18 @@
+open class Base {
+    open val x: Int = 1
+        get() = field - 1
+}
+
+class Other: Base() {
+    override val x = 2
+}
+
+class Another: Base() {
+    override val x = 3
+        get() = field + 1
+}
+
+class NoBackingField: Base() {
+    override val x: Int
+        get() = 5
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldInInterface.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldInInterface.fir.kt
new file mode 100644
index 00000000000..991779fad58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldInInterface.fir.kt
@@ -0,0 +1,4 @@
+interface My {
+    val x: Int = 0
+        get() = field
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldInLocal.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldInLocal.fir.kt
new file mode 100644
index 00000000000..cc14a9b10cd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldInLocal.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+fun foo() {
+    open class Local {
+        val my: Int = 2
+            get() = field
+    }
+    val your = object: Local() {
+        val your: Int = 3
+            get() = field
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldOnVal.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldOnVal.fir.kt
new file mode 100644
index 00000000000..02554ee0a3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldOnVal.fir.kt
@@ -0,0 +1,2 @@
+val my: Int = 21
+    get() = field * 2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldOnVar.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldOnVar.fir.kt
new file mode 100644
index 00000000000..882c035d8e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldOnVar.fir.kt
@@ -0,0 +1,5 @@
+var my: Int = 0
+    get() = -field
+    set(arg) {
+        field = arg
+    }
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldReassignment_after.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldReassignment_after.fir.kt
new file mode 100644
index 00000000000..a082948fe44
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldReassignment_after.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: +RestrictionOfValReassignmentViaBackingField
+
+val my: Int = 1
+    get() {
+        field++
+        return field
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldReassignment_before.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldReassignment_before.fir.kt
new file mode 100644
index 00000000000..660a0ee1d2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldReassignment_before.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: -RestrictionOfValReassignmentViaBackingField
+
+val my: Int = 1
+    get() {
+        field++
+        return field
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/FieldShadow.fir.kt b/compiler/testData/diagnostics/tests/backingField/FieldShadow.fir.kt
new file mode 100644
index 00000000000..32add099380
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/FieldShadow.fir.kt
@@ -0,0 +1,8 @@
+class My {
+    // No initialization needed because no backing field
+    val two: Int
+        get() {
+            val field = 2
+            return field
+        }
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/InitCustomSetter.fir.kt b/compiler/testData/diagnostics/tests/backingField/InitCustomSetter.fir.kt
new file mode 100644
index 00000000000..b96daa2263e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/InitCustomSetter.fir.kt
@@ -0,0 +1,30 @@
+class My(val v: Int) {
+    // Ok: setter is just private
+    var x: Int
+        private set
+
+    var y: Int
+        set(arg) { field = arg }
+
+    var z: Int
+        set(arg) { field = arg }
+
+    // Ok: initializer available
+    var w: Int = v
+        set(arg) { field = arg }
+
+    // Ok: no backing field
+    var u: Int
+        get() = w
+        set(arg) { w = 2 * arg }
+
+    constructor(): this(0) {
+        z = v        
+    }
+
+    init {
+        x = 1
+        y = 2
+        u = 3
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/InitOpenSetter.fir.kt b/compiler/testData/diagnostics/tests/backingField/InitOpenSetter.fir.kt
new file mode 100644
index 00000000000..6a8de3b254b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/InitOpenSetter.fir.kt
@@ -0,0 +1,27 @@
+abstract class My(val v: Int) {
+    // Ok: variable is just abstract
+    abstract var x: Int
+
+    open var y: Int
+
+    open var z: Int
+
+    // Ok: initializer available
+    open var w: Int = v
+        set(arg) { field = arg }    
+
+    // Ok: no backing field, no initializer possible
+    open var u: Int
+        get() = w
+        set(arg) { w = 2 * arg }
+
+    constructor(): this(0) {
+        z = v
+    }
+
+    init {
+        x = 1
+        y = 2
+        u = 3
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/backingField/SetterWithExplicitType.fir.kt b/compiler/testData/diagnostics/tests/backingField/SetterWithExplicitType.fir.kt
new file mode 100644
index 00000000000..2a343535976
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/SetterWithExplicitType.fir.kt
@@ -0,0 +1,26 @@
+// KT-7042 Providing return type for property setter is not reported as error
+
+var x: Int = 1
+
+// No backing field!
+var y: Int
+    get() = x
+    set(value): Any {
+        x = value
+    }
+
+var z: Int
+    get() = x
+    set(value): Unit {
+        x = value
+    }
+
+var u: String = ""
+    set(value): Unit {
+        field = value
+    }
+
+var v: String = ""
+    set(value): String {
+        field = value
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/backingField/kt782packageLevel.fir.kt b/compiler/testData/diagnostics/tests/backingField/kt782packageLevel.fir.kt
new file mode 100644
index 00000000000..a5bd01f37dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/backingField/kt782packageLevel.fir.kt
@@ -0,0 +1,16 @@
+// KT-782 Allow backing field usage for accessors of variables on namespace level
+
+package kt782
+
+val z : Int = 34
+
+val y : Int = 11
+get() {
+    return field
+}
+
+val x : Int
+get() = z
+
+val w : Int = 56
+get() = field
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/bareType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bareType.fir.kt
new file mode 100644
index 00000000000..34cf4aafe65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bareType.fir.kt
@@ -0,0 +1,8 @@
+fun f1() = Map::hashCode
+fun f2() = Map.Entry::hashCode
+
+class Outer<T> {
+    inner class Inner
+}
+
+fun f3() = Outer.Inner::hashCode
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/classVsStarImportedCompanion.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/classVsStarImportedCompanion.fir.kt
new file mode 100644
index 00000000000..870501ae0fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/classVsStarImportedCompanion.fir.kt
@@ -0,0 +1,18 @@
+// FILE: 1.kt
+
+package a
+
+import b.B.*
+import kotlin.reflect.KClass
+
+class Companion
+
+val f: KClass<a.Companion> = Companion::class
+
+// FILE: 2.kt
+
+package b
+
+class B {
+    companion object Companion
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/classVsStarImportedObject.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/classVsStarImportedObject.fir.kt
new file mode 100644
index 00000000000..0b2434d7c0d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/classVsStarImportedObject.fir.kt
@@ -0,0 +1,19 @@
+// FILE: 1.kt
+
+package a
+
+import b.*
+import kotlin.reflect.KClass
+
+class A
+object B
+
+val f: KClass<a.A> = A::class
+val g: KClass<a.B> = B::class
+
+// FILE: 2.kt
+
+package b
+
+object A
+object B
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/companionObject.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/companionObject.fir.kt
new file mode 100644
index 00000000000..bd6cd6dc7e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/companionObject.fir.kt
@@ -0,0 +1,39 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+package test
+
+class C {
+    companion object {
+        fun foo(): String = "companion"
+        fun bar() {}
+    }
+
+    fun foo(): Int = 0
+}
+
+fun test() {
+    val r1 = C::foo
+    checkSubtype<(C) -> Int>(r1)
+
+    val r2 = test.C::foo
+    checkSubtype<(C) -> Int>(r2)
+
+    val r3 = C.Companion::foo
+    checkSubtype<() -> String>(r3)
+
+    val r4 = test.C.Companion::foo
+    checkSubtype<() -> String>(r4)
+
+    val r5 = (C)::foo
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><() -> String>(r5)
+
+    val r6 = (test.C)::foo
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><() -> String>(r6)
+
+    val c = C.Companion
+    val r7 = c::foo
+    checkSubtype<() -> String>(r7)
+
+    C::bar
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/controlFlow.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/controlFlow.fir.kt
new file mode 100644
index 00000000000..a7879898c7c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/controlFlow.fir.kt
@@ -0,0 +1,22 @@
+fun unusedExpression(s: String) {
+    s::hashCode
+    s::class
+}
+
+fun noUnusedParameter(s: String): Int {
+    val f = s::hashCode
+    return f()
+}
+
+fun unreachableCode(): Int {
+    (if (true) return 1 else return 0)::toString
+    return 0
+}
+
+fun unreachableCodeInLoop(): Int {
+    while (true) {
+        (break)::toString
+        return 1
+    }
+    return 2
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/dataFlow.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/dataFlow.fir.kt
new file mode 100644
index 00000000000..cd0dbeda4ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/dataFlow.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+import kotlin.reflect.KClass
+
+fun f1(x: String?): String {
+    x!!::hashCode
+    return x
+}
+
+fun f2(y: String?): String {
+    val f: KClass<*> = (y ?: return "")::class
+    return y
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/expectedType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/expectedType.fir.kt
new file mode 100644
index 00000000000..2babceacb13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/expectedType.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+import kotlin.reflect.KClass
+
+fun test(s: String) {
+    val f: () -> Int = s::hashCode
+    val g: () -> String = s::toString
+    val h: (Any?) -> Boolean = s::equals
+
+    val k: KClass<out String> = s::class
+    val l: KClass<*> = s::class
+    val m: KClass<String> = String::class
+    val n: KClass<Unit> = Unit::class
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/expressionWithNullableType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/expressionWithNullableType.fir.kt
new file mode 100644
index 00000000000..90a9adae93b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/expressionWithNullableType.fir.kt
@@ -0,0 +1,15 @@
+// FILE: J.java
+
+public interface J {
+    String platformString();
+}
+
+// FILE: test.kt
+
+fun f1(x: Int?): Any = x::hashCode
+fun <T> f2(t: T): Any = t::hashCode
+fun <S : String?> f3(s: S): Any = s::hashCode
+fun <U : Any> f4(u: U?): Any = u::hashCode
+fun f5(c: List<*>): Any = c[0]::hashCode
+
+fun f6(j: J): Any = j.platformString()::hashCode
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/functionCallWithoutArguments.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/functionCallWithoutArguments.fir.kt
new file mode 100644
index 00000000000..be9c7e33b9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/functionCallWithoutArguments.fir.kt
@@ -0,0 +1 @@
+fun test() = ("").<!UNRESOLVED_REFERENCE!>hashCode<!>::hashCode
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/innerNested.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/innerNested.fir.kt
new file mode 100644
index 00000000000..07582d6980f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/innerNested.fir.kt
@@ -0,0 +1,9 @@
+class Outer {
+    class Nested
+    inner class Inner
+}
+
+fun test() {
+    Outer()::Inner
+    Outer()::Nested
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/kt12843.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/kt12843.fir.kt
new file mode 100644
index 00000000000..18df77a2d46
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/kt12843.fir.kt
@@ -0,0 +1,6 @@
+class Foo {
+    fun bar() {}
+    fun f() = <!UNRESOLVED_REFERENCE!>Unresolved<!>()::bar
+}
+
+val f: () -> Unit = <!UNRESOLVED_REFERENCE!>Unresolved<!>()::foo
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/noThisInSuperCall.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/noThisInSuperCall.fir.kt
new file mode 100644
index 00000000000..79bbc332054
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/noThisInSuperCall.fir.kt
@@ -0,0 +1,3 @@
+open class A(val x: Any)
+
+class B : A(this::class)
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/object.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/object.fir.kt
new file mode 100644
index 00000000000..d2b6f013005
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/object.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+object Obj {
+    fun foo() {}
+    val bar = 2
+}
+
+fun test() {
+    checkSubtype<() -> Unit>(Obj::foo)
+    checkSubtype<() -> Int>(Obj::bar)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/privateToThis.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/privateToThis.fir.kt
new file mode 100644
index 00000000000..e578a364358
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/privateToThis.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+class Foo<out T>(name: T) {
+    private var prop: T = name
+        private set
+
+    fun testProp() {
+        val ok1 = this::prop
+        val ok2 = this@Foo::prop
+        val ok3 = object { val y: Any = this@Foo::prop }
+
+        val fail1 = Foo(prop)::prop
+    }
+
+    fun testFunc() {
+        val ok1 = this::func
+        val ok2 = this@Foo::func
+        val ok3 = object { val y: Any = this@Foo::func }
+
+        val fail1 = Foo(prop)::func
+    }
+
+    private fun func(t: T): T = t
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/referenceToStaticMethodOnInstance.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/referenceToStaticMethodOnInstance.fir.kt
new file mode 100644
index 00000000000..656a0a5d6dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/referenceToStaticMethodOnInstance.fir.kt
@@ -0,0 +1,14 @@
+// FILE: A.java
+
+public class A {
+    public static void test() {}
+}
+
+// FILE: test.kt
+
+enum class E { EN }
+
+fun test() {
+    A()::test
+    E.EN::valueOf
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax.fir.kt
new file mode 100644
index 00000000000..554a28491c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax.fir.kt
@@ -0,0 +1,33 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+package test
+
+object ClassMemberMarker
+
+class a<T> {
+    fun foo() = ClassMemberMarker
+}
+
+class b<T1, T2> {
+    fun foo() = ClassMemberMarker
+}
+
+fun Int.foo() {}
+
+class Test {
+    val <T> List<T>.a: Int get() = size
+    val <T> List<T>.b: Int? get() = size
+
+    fun <T> List<T>.testCallable1(): () -> Unit = a<T>::foo
+    fun <T> List<T>.testCallable2(): () -> Unit = b?::foo
+    fun <T> List<T>.testCallable3(): () -> Unit = b<T, Any>::foo
+    fun <T> List<T>.testCallable4(): () -> Unit = b<T>?::foo
+
+    fun <T> List<T>.testClassLiteral1() = a<T>::class
+    fun <T> List<T>.testClassLiteral2() = b?::class
+    fun <T> List<T>.testClassLiteral3() = b<T, Any>::class
+
+    fun <T> List<T>.testUnresolved1() = <!UNRESOLVED_REFERENCE!>unresolved<!><T>::foo
+    fun <T> List<T>.testUnresolved2() = a<unresolved>::foo
+    fun <T> List<T>.testUnresolved3() = a<<!SYNTAX!><!>>::foo
+    fun <T> List<T>.testUnresolved4() = <!UNRESOLVED_REFERENCE!>unresolved<!>?::foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax2.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax2.fir.kt
new file mode 100644
index 00000000000..1283a601da5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax2.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+package test
+
+fun nullableFun(): Int? = null
+fun Int.foo() {}
+
+val test1 = nullableFun()?::foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax3.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax3.fir.kt
new file mode 100644
index 00000000000..06998a2aa87
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/reservedExpressionSyntax3.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+package test
+
+object Wrong
+object Right
+
+class a {
+    class b<T> {
+        class c {
+            fun foo() = Wrong
+        }
+    }
+}
+
+fun Int.foo() = Right
+
+class Test {
+    val a: List<Int> = null!!
+
+    val <T> List<T>.b: Int get() = 42
+
+    val Int.c: Int get() = 42
+
+    val test1: () -> Right = a.b<Int>.c::foo
+    val test1a: () -> Right = a.b.c::foo
+
+    val test2: () -> Right = a.b<Int>.c?::foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/syntheticExtensionOnLHS.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/syntheticExtensionOnLHS.fir.kt
new file mode 100644
index 00000000000..43b869004af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/syntheticExtensionOnLHS.fir.kt
@@ -0,0 +1,13 @@
+// FILE: A.java
+
+class A {
+    public CharSequence getFoo() { return null; }
+}
+
+// FILE: test.kt
+
+fun test() {
+    with (A()) {
+        foo::toString
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/bound/valueOfTypeParameterType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/bound/valueOfTypeParameterType.fir.kt
new file mode 100644
index 00000000000..928a186a85c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/bound/valueOfTypeParameterType.fir.kt
@@ -0,0 +1,3 @@
+fun <T: Any> get(t: T): () -> String {
+    return t::toString
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/callableReferenceAsLastExpressionInBlock.fir.kt b/compiler/testData/diagnostics/tests/callableReference/callableReferenceAsLastExpressionInBlock.fir.kt
new file mode 100644
index 00000000000..a70957b6ada
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/callableReferenceAsLastExpressionInBlock.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+fun test() {
+    val a = if (true) {
+        val x = 1
+        "".length
+        <!UNRESOLVED_REFERENCE!>::foo<!>
+    } else {
+        <!UNRESOLVED_REFERENCE!>::foo<!>
+    }
+    a checkType {  <!UNRESOLVED_REFERENCE!>_<!><KFunction0<Int>>() }
+}
+
+fun foo(): Int = 0
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/classVsPackage.fir.kt b/compiler/testData/diagnostics/tests/callableReference/classVsPackage.fir.kt
new file mode 100644
index 00000000000..13c46fdf61e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/classVsPackage.fir.kt
@@ -0,0 +1,24 @@
+// MODULE: m1
+// FILE: 1.kt
+
+package a
+
+class b {
+    class c
+}
+
+// MODULE: m2
+// FILE: 2.kt
+
+package a.b
+
+class c {
+    fun foo() {}
+}
+
+// MODULE: m3(m1, m2)
+// FILE: test.kt
+
+package test
+
+fun test() = a.b.c::foo
diff --git a/compiler/testData/diagnostics/tests/callableReference/constraintFromLHSWithCorrectDirection.fir.kt b/compiler/testData/diagnostics/tests/callableReference/constraintFromLHSWithCorrectDirection.fir.kt
new file mode 100644
index 00000000000..cc06049c5b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/constraintFromLHSWithCorrectDirection.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty1
+
+interface A
+inline val <T : A> T.bla get() = 1
+
+class B<T>
+fun <K, V> B<K>.foo(p: KProperty1<in K, V>): B<V> = TODO()
+
+fun <K, V> B<out K>.bar(p: KProperty1<out K, V>): B<V> = TODO()
+
+fun <K, V> B<K>.baz(p: KProperty1<out K, V>): B<V> = TODO()
+
+fun <K, V> B<K>.star(p: KProperty1<*, V>): B<V> = TODO()
+
+
+fun <R : A> B<R>.test(){
+    foo(A::bla)
+    bar(A::bla)
+    <!INAPPLICABLE_CANDIDATE!>baz<!>(A::bla)
+    star(A::bla)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/correctInfoAfterArrayLikeCall.fir.kt b/compiler/testData/diagnostics/tests/callableReference/correctInfoAfterArrayLikeCall.fir.kt
new file mode 100644
index 00000000000..ccfc84684b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/correctInfoAfterArrayLikeCall.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty1
+
+class DTO {
+    val q: Int = 0
+    operator fun get(prop: KProperty1<*, Int>): Int = 0
+}
+
+fun foo(intDTO: DTO?, p: KProperty1<*, Int>) {
+    if (intDTO != null) {
+        intDTO[DTO::q]
+        intDTO.q
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/ea81649_errorPropertyLHS.fir.kt b/compiler/testData/diagnostics/tests/callableReference/ea81649_errorPropertyLHS.fir.kt
new file mode 100644
index 00000000000..c477e447579
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/ea81649_errorPropertyLHS.fir.kt
@@ -0,0 +1,20 @@
+// Different modules are important for this test because otherwise everything is analyzed at once and some errors
+// already exist in the binding context when we're analyzing "User::surname".
+// (The assertion at DoubleColonExpressionResolver.checkNoExpressionOnLHS is only performed when there are no errors in the binding context)
+
+// MODULE: m1
+// FILE: bar.kt
+
+fun <T> bar(ff: Err.() -> Unit) {
+}
+
+// MODULE: m2(m1)
+// FILE: foo.kt
+
+data class User(val surname: String)
+
+fun foo() {
+    bar<String> {
+        User::surname
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/emptyLhs.fir.kt b/compiler/testData/diagnostics/tests/callableReference/emptyLhs.fir.kt
new file mode 100644
index 00000000000..cf009c8a4fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/emptyLhs.fir.kt
@@ -0,0 +1,41 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION, -EXTENSION_SHADOWED_BY_MEMBER
+// !LANGUAGE: +CallableReferencesToClassMembersWithEmptyLHS
+
+val topLevelVal = 1
+fun topLevelFun() = 2
+
+val A.extensionVal: Int get() = 3
+fun A.extensionFun(): Int = 4
+
+class A {
+    val memberVal = 5
+    fun memberFun() = 6
+
+    val ok1 = ::topLevelVal
+    val ok2 = ::topLevelFun
+
+    fun fail1() {
+        ::extensionVal
+        ::extensionFun
+    }
+
+    fun fail2() {
+        ::memberVal
+        ::memberFun
+    }
+}
+
+
+
+val ok1 = ::topLevelVal
+val ok2 = ::topLevelFun
+
+fun A.fail1() {
+    ::extensionVal
+    ::extensionFun
+}
+
+fun A.fail2() {
+    ::memberVal
+    ::memberFun
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/expectedTypeAsSubtypeOfFunctionType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/expectedTypeAsSubtypeOfFunctionType.fir.kt
new file mode 100644
index 00000000000..affb0318308
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/expectedTypeAsSubtypeOfFunctionType.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+abstract class SubFunction : kotlin.Function0<Unit>
+
+fun <T> takeIt(x: T, f: SubFunction) {}
+
+fun cr() {}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>takeIt<!>(42, ::cr)
+    <!INAPPLICABLE_CANDIDATE!>takeIt<!>(42, { })
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/abstractClassConstructors.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/abstractClassConstructors.fir.kt
new file mode 100644
index 00000000000..82e9593dd3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/abstractClassConstructors.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+interface A
+abstract class B
+annotation class C
+enum class D
+
+fun main() {
+    ::A
+    ::B
+    ::C   // KT-3465
+    ::D
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/ambiguityTopLevelVsTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/ambiguityTopLevelVsTopLevel.fir.kt
new file mode 100644
index 00000000000..ccddcecf6a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/ambiguityTopLevelVsTopLevel.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION,-UNUSED_VARIABLE
+fun foo(x: Int, y: Any) = x
+fun foo(x: Any, y: Int) = y
+
+fun main() {
+    <!UNRESOLVED_REFERENCE!>::foo<!>
+    
+    val fooRef: (Int, Any) -> Unit = <!UNRESOLVED_REFERENCE!>::foo<!>
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/annotationClassConstructor.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/annotationClassConstructor.fir.kt
new file mode 100644
index 00000000000..1fac9d054b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/annotationClassConstructor.fir.kt
@@ -0,0 +1,5 @@
+annotation class Ann(val prop: String)
+
+val annCtorRef = ::Ann
+val annClassRef = Ann::class
+val annPropRef = Ann::prop
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/callableRefrenceOnNestedObject.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/callableRefrenceOnNestedObject.fir.kt
new file mode 100644
index 00000000000..76c0a667973
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/callableRefrenceOnNestedObject.fir.kt
@@ -0,0 +1,9 @@
+open class A {
+    fun foo() = 42
+
+    object B: A()
+}
+
+fun test() {
+    (A::foo)(A.B)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/classMemberVsConstructorLikeFunction.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/classMemberVsConstructorLikeFunction.fir.kt
new file mode 100644
index 00000000000..5b1cccdd062
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/classMemberVsConstructorLikeFunction.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Foo.kt
+
+package test
+
+class Foo {
+    fun bar() {}
+}
+
+// FILE: test.kt
+
+import test.Foo
+
+fun Foo(): String = ""
+
+val f = Foo::bar
+val g = Foo::length
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/constructorFromClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromClass.fir.kt
new file mode 100644
index 00000000000..fef4ee7ca36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromClass.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+class A {
+    fun main() {
+        val x = ::A
+
+        checkSubtype<KFunction0<A>>(x)
+    }
+}
+
+class SomeOtherClass {
+    fun main() {
+        val x = ::A
+
+        checkSubtype<KFunction0<A>>(x)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/constructorFromCompanion.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromCompanion.fir.kt
new file mode 100644
index 00000000000..fef220c5282
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromCompanion.fir.kt
@@ -0,0 +1,22 @@
+// FILE: A.kt
+
+open class A<T>(val x: T)
+
+// FILE: AFactory.kt
+
+abstract class AFactory {
+    abstract fun create(): A<Int>?
+}
+
+// FILE: Util.kt
+
+inline fun <reified T> createWith(x: T, f: (T) -> A<T>?)
+        = f(x)
+
+// FILE: B.kt
+
+class B(x: Int) : A<Int>(x) {
+    companion object : AFactory() {
+        override fun create(): A<Int>? = createWith(0, ::B)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/constructorFromExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromExtension.fir.kt
new file mode 100644
index 00000000000..07c789acecf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromExtension.fir.kt
@@ -0,0 +1,14 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+class A
+class B
+
+fun A.ext() {
+    val x = ::A
+    val y = ::B
+
+    checkSubtype<KFunction0<A>>(x)
+    checkSubtype<KFunction0<B>>(y)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/constructorFromExtensionInClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromExtensionInClass.fir.kt
new file mode 100644
index 00000000000..56af7cecad4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromExtensionInClass.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+class A
+
+class B {
+    fun A.ext() {
+        val x = ::A
+        val y = ::B
+
+        checkSubtype<KFunction0<A>>(x)
+        checkSubtype<KFunction0<B>>(y)
+    }
+    
+    fun B.ext() {
+        val x = ::A
+        val y = ::B
+
+        checkSubtype<KFunction0<A>>(x)
+        checkSubtype<KFunction0<B>>(y)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/constructorFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromTopLevel.fir.kt
new file mode 100644
index 00000000000..4417c6fdef1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/constructorFromTopLevel.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+class A
+
+fun main() {
+    val x = ::A
+
+    checkSubtype<KFunction0<A>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/constructorOfNestedClassInObject.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/constructorOfNestedClassInObject.fir.kt
new file mode 100644
index 00000000000..4c218d67696
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/constructorOfNestedClassInObject.fir.kt
@@ -0,0 +1,21 @@
+// KT-15951 Callable reference to class constructor from object is not resolved
+
+object A {
+    class Wrapper
+}
+
+class Outer {
+    companion object {
+        class Wrapper
+    }
+}
+
+fun test() {
+    A::Wrapper
+    (A)::Wrapper
+
+    Outer.Companion::Wrapper
+    (Outer.Companion)::Wrapper
+    Outer::Wrapper
+    (Outer)::Wrapper
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/differentPackageClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/differentPackageClass.fir.kt
new file mode 100644
index 00000000000..f25fc6ddbc7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/differentPackageClass.fir.kt
@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+// FILE: a.kt
+
+package first
+
+class A {
+    fun foo() {}
+    fun bar(x: Int) {}
+    fun baz() = "OK"
+}
+
+// FILE: b.kt
+
+package other
+
+import kotlin.reflect.*
+
+import first.A
+
+fun main() {
+    val x = first.A::foo
+    val y = first.A::bar
+    val z = A::baz
+
+    checkSubtype<KFunction1<A, Unit>>(x)
+    checkSubtype<KFunction2<A, Int, Unit>>(y)
+    checkSubtype<KFunction1<A, String>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/differentPackageExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/differentPackageExtension.fir.kt
new file mode 100644
index 00000000000..7668bc02168
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/differentPackageExtension.fir.kt
@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// FILE: a.kt
+
+package first
+
+class A
+
+fun A.foo() {}
+fun A.bar() {}
+fun A.baz() {}
+
+// FILE: b.kt
+
+package other
+
+import kotlin.reflect.KFunction1
+
+import first.A
+import first.foo
+
+fun main() {
+    val x = first.A::foo
+    first.A::bar
+    A::baz
+
+    checkSubtype<KFunction1<A, Unit>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/differentPackageTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/differentPackageTopLevel.fir.kt
new file mode 100644
index 00000000000..0f7f02af9f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/differentPackageTopLevel.fir.kt
@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+// FILE: a.kt
+
+package first
+
+fun foo() {}
+fun bar(x: Int) {}
+fun baz() = "OK"
+
+// FILE: b.kt
+
+package other
+
+import kotlin.reflect.*
+
+import first.foo
+import first.bar
+import first.baz
+
+fun main() {
+    val x = ::foo
+    val y = ::bar
+    val z = ::baz
+
+    checkSubtype<KFunction0<Unit>>(x)
+    checkSubtype<KFunction1<Int, Unit>>(y)
+    checkSubtype<KFunction0<String>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/empty.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/empty.fir.kt
new file mode 100644
index 00000000000..243660cb419
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/empty.fir.kt
@@ -0,0 +1,6 @@
+class A
+
+fun main() {
+    val x = :: <!SYNTAX!><!>;
+    val y = A::
+<!SYNTAX!><!>}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/extensionFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/extensionFromTopLevel.fir.kt
new file mode 100644
index 00000000000..2ecb137ed46
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/extensionFromTopLevel.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class A
+
+fun A.foo() {}
+fun A.bar(x: Int) {}
+fun A.baz() = "OK"
+
+fun main() {
+    val x = A::foo
+    val y = A::bar
+    val z = A::baz
+
+    checkSubtype<KFunction1<A, Unit>>(x)
+    checkSubtype<KFunction2<A, Int, Unit>>(y)
+    checkSubtype<KFunction1<A, String>>(z)
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction<Unit>>(x)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction<Unit>>(y)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction<String>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/extensionInClassDisallowed.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/extensionInClassDisallowed.fir.kt
new file mode 100644
index 00000000000..8ece6d0a2f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/extensionInClassDisallowed.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+class A {
+    fun Int.extInt() = 42
+    fun A.extA(x: String) = x
+    
+    fun main() {
+        Int::extInt
+        A::extA
+
+        eat(Int::extInt)
+        eat(A::extA)
+    }
+}
+
+fun eat(value: Any) {}
+
+fun main() {
+    A::extInt
+    A::extA
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/extensionOnNullable.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/extensionOnNullable.fir.kt
new file mode 100644
index 00000000000..5434e7241ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/extensionOnNullable.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS:-UNUSED_VARIABLE
+
+import kotlin.reflect.*
+
+class A {
+    fun foo() {}
+}
+
+fun A?.foo() {}
+
+val f: KFunction1<A, Unit> = A::foo
+val g: KFunction1<A, Unit> = A?::foo
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/extensionToSupertype.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/extensionToSupertype.fir.kt
new file mode 100644
index 00000000000..719a03b5e61
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/extensionToSupertype.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.*
+
+interface A
+interface B : A
+
+fun A.foo() {}
+
+fun take(f: (A) -> Unit) {}
+fun take(f: () -> Unit) {}
+
+fun test() {
+    B::foo checkType { <!UNRESOLVED_REFERENCE!>_<!><KFunction1<B, Unit>>() }
+
+    take(B::foo)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/fakeOverrideType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/fakeOverrideType.fir.kt
new file mode 100644
index 00000000000..821dffbb84b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/fakeOverrideType.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction2
+
+open class A {
+    fun foo(s: String): String = s
+}
+
+class B : A() {
+}
+
+
+fun test() {
+    B::foo checkType { <!UNRESOLVED_REFERENCE!>_<!><KFunction2<B, String, String>>() }
+
+    <!INAPPLICABLE_CANDIDATE!>(B::hashCode)("No.")<!>
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/genericClassFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/genericClassFromTopLevel.fir.kt
new file mode 100644
index 00000000000..3ebdabd9df1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/genericClassFromTopLevel.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction1
+
+class A<T>(val t: T) {
+    fun foo(): T = t
+}
+
+fun bar() {
+    val x = A<String>::foo
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction1<A<String>, String>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/importedInnerConstructor.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/importedInnerConstructor.fir.kt
new file mode 100644
index 00000000000..d41aab8ba36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/importedInnerConstructor.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+import A.Inner
+
+class A {
+    inner class Inner
+}
+
+fun main() {
+    ::Inner
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromClass.fir.kt
new file mode 100644
index 00000000000..5141391eb96
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromClass.fir.kt
@@ -0,0 +1,34 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// !LANGUAGE: +CallableReferencesToClassMembersWithEmptyLHS
+
+import kotlin.reflect.KFunction1
+
+class A {
+    inner class Inner
+    
+    fun main() {
+        ::Inner
+        val y = A::Inner
+
+        checkSubtype<KFunction1<A, Inner>>(y)
+    }
+    
+    companion object {
+        fun main() {
+            ::Inner
+            val y = A::Inner
+
+            checkSubtype<KFunction1<A, A.Inner>>(y)
+        }
+    }
+}
+
+class B {
+    fun main() {
+        ::Inner
+        val y = A::Inner
+
+        checkSubtype<KFunction1<A, A.Inner>>(y)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromExtension.fir.kt
new file mode 100644
index 00000000000..e7fb089d9b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromExtension.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// !LANGUAGE: +CallableReferencesToClassMembersWithEmptyLHS
+
+import kotlin.reflect.KFunction1
+
+class A {
+    inner class Inner
+}
+    
+fun A.main() {
+    ::Inner
+    val y = A::Inner
+
+    checkSubtype<KFunction1<A, A.Inner>>(y)
+}
+
+fun Int.main() {
+    ::Inner
+    val y = A::Inner
+
+    checkSubtype<KFunction1<A, A.Inner>>(y)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromTopLevel.fir.kt
new file mode 100644
index 00000000000..fa27fdca024
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/innerConstructorFromTopLevel.fir.kt
@@ -0,0 +1,14 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+import kotlin.reflect.KFunction1
+
+class A {
+    inner class Inner
+}
+
+fun main() {
+    ::Inner
+    val y = A::Inner
+
+    checkSubtype<KFunction1<A, A.Inner>>(y)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/javaStaticMethod.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/javaStaticMethod.fir.kt
new file mode 100644
index 00000000000..405cf28f0f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/javaStaticMethod.fir.kt
@@ -0,0 +1,24 @@
+// !CHECK_TYPE
+// FILE: test/A.java
+
+package test;
+
+import java.util.Arrays;
+
+public class A {
+    public static void main(String[] args) {
+        System.out.println(Arrays.asList(args));
+    }
+}
+
+// FILE: 1.kt
+
+import kotlin.reflect.*
+import test.A
+
+fun foo(args: Array<String>) {
+    val main2 = A::main
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction1<Array<String>, Unit>>(main2)
+    <!INAPPLICABLE_CANDIDATE!>main2<!>(args)
+    <!INAPPLICABLE_CANDIDATE!>(A::main)(args)<!>
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/lhsNotAClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/lhsNotAClass.fir.kt
new file mode 100644
index 00000000000..f4f652c3b83
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/lhsNotAClass.fir.kt
@@ -0,0 +1,9 @@
+class A<T, U : Any> {
+    fun foo() = <!OTHER_ERROR!>T<!>::toString
+
+    fun bar() = <!OTHER_ERROR!>U<!>::toString
+}
+
+fun <T> foo() = <!OTHER_ERROR!>T<!>::toString
+
+fun <U : Any> bar() = <!OTHER_ERROR!>U<!>::toString
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localConstructor.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localConstructor.fir.kt
new file mode 100644
index 00000000000..d42785c511b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localConstructor.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+fun main() {
+    class A
+    
+    val x = ::A
+    checkSubtype<KFunction0<A>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromExtensionInLocalClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromExtensionInLocalClass.fir.kt
new file mode 100644
index 00000000000..28dcb81eeaa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromExtensionInLocalClass.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+fun main() {
+    class A
+    
+    class B {
+        fun Int.foo() {
+            val x = ::A
+            checkSubtype<KFunction0<A>>(x)
+        }
+        fun A.foo() {
+            val x = ::A
+            checkSubtype<KFunction0<A>>(x)
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromLocalClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromLocalClass.fir.kt
new file mode 100644
index 00000000000..0bcab8a24d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromLocalClass.fir.kt
@@ -0,0 +1,10 @@
+import kotlin.reflect.KFunction0
+
+fun main() {
+    class A
+    
+    class B {
+        val x = ::A
+        val f: KFunction0<A> = x
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromLocalExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromLocalExtension.fir.kt
new file mode 100644
index 00000000000..9fd725f079d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localConstructorFromLocalExtension.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+fun main() {
+    class A
+    
+    fun A.foo() {
+        val x = ::A
+        checkSubtype<KFunction0<A>>(x)
+    }
+    
+    fun Int.foo() {
+        val x = ::A
+        checkSubtype<KFunction0<A>>(x)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localNamedFun.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFun.fir.kt
new file mode 100644
index 00000000000..c528b387fb7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFun.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+fun main() {
+    fun foo() {}
+    fun bar(x: Int) {}
+    fun baz() = "OK"
+    
+    val x = ::foo
+    val y = ::bar
+    val z = ::baz
+    
+    checkSubtype<KFunction0<Unit>>(x)
+    checkSubtype<KFunction1<Int, Unit>>(y)
+    checkSubtype<KFunction0<String>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromExtensionInLocalClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromExtensionInLocalClass.fir.kt
new file mode 100644
index 00000000000..066194937bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromExtensionInLocalClass.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class A
+
+fun main() {
+    fun foo() {}
+    fun bar(x: Int) {}
+    fun baz() = "OK"
+    
+    class B {
+        fun A.ext() {
+            val x = ::foo
+            val y = ::bar
+            val z = ::baz
+
+            checkSubtype<KFunction0<Unit>>(x)
+            checkSubtype<KFunction1<Int, Unit>>(y)
+            checkSubtype<KFunction0<String>>(z)
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromLocalClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromLocalClass.fir.kt
new file mode 100644
index 00000000000..87aa5961b1f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromLocalClass.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+fun main() {
+    fun foo() {}
+    fun bar(x: Int) {}
+    fun baz() = "OK"
+    
+    class A {
+        val x = ::foo
+        val y = ::bar
+        val z = ::baz
+
+        fun main() {
+            checkSubtype<KFunction0<Unit>>(x)
+            checkSubtype<KFunction1<Int, Unit>>(y)
+            checkSubtype<KFunction0<String>>(z)
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromLocalExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromLocalExtension.fir.kt
new file mode 100644
index 00000000000..d4621ce0203
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/localNamedFunFromLocalExtension.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class A
+
+fun main() {
+    fun foo() {}
+    fun bar(x: Int) {}
+    fun baz() = "OK"
+    
+    fun A.ext() {
+        val x = ::foo
+        val y = ::bar
+        val z = ::baz
+
+        checkSubtype<KFunction0<Unit>>(x)
+        checkSubtype<KFunction1<Int, Unit>>(y)
+        checkSubtype<KFunction0<String>>(z)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/longQualifiedName.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/longQualifiedName.fir.kt
new file mode 100644
index 00000000000..143296f288d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/longQualifiedName.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+// FILE: a.kt
+
+package a.b.c
+
+class D {
+    fun foo() = 42
+}
+
+// FILE: b.kt
+
+import kotlin.reflect.KFunction1
+
+fun main() {
+    val x = a.b.c.D::foo
+
+    checkSubtype<KFunction1<a.b.c.D, Int>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/longQualifiedNameGeneric.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/longQualifiedNameGeneric.fir.kt
new file mode 100644
index 00000000000..df53d4d2ccb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/longQualifiedNameGeneric.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+// FILE: a.kt
+
+package a.b.c
+
+class D<E, F> {
+    fun foo(e: E, f: F) = this
+}
+
+// FILE: b.kt
+
+import kotlin.reflect.KFunction3
+
+fun main() {
+    val x = a.b.c.D<String, Int>::foo
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction3<a.b.c.D<String, Int>, String, Int, a.b.c.D<String, Int>>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/memberFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/memberFromTopLevel.fir.kt
new file mode 100644
index 00000000000..fdbe223f494
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/memberFromTopLevel.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class A {
+    fun foo() {}
+    fun bar(x: Int) {}
+    fun baz() = "OK"
+}
+
+fun main() {
+    val x = A::foo
+    val y = A::bar
+    val z = A::baz
+
+    checkSubtype<KFunction1<A, Unit>>(x)
+    checkSubtype<KFunction2<A, Int, Unit>>(y)
+    checkSubtype<KFunction1<A, String>>(z)
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction<Unit>>(x)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction<Unit>>(y)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction<String>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromClass.fir.kt
new file mode 100644
index 00000000000..bdeaa0b46d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromClass.fir.kt
@@ -0,0 +1,33 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+import kotlin.reflect.KFunction0
+
+class A {
+    class Nested
+    
+    fun main() {
+        val x = ::Nested
+        val y = A::Nested
+
+        checkSubtype<KFunction0<Nested>>(x)
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction0<Nested>>(y)
+    }
+    
+    companion object {
+        fun main() {
+            ::Nested
+            val y = A::Nested
+
+            <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction0<A.Nested>>(y)
+        }
+    }
+}
+
+class B {
+    fun main() {
+        ::Nested
+        val y = A::Nested
+
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction0<A.Nested>>(y)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromExtension.fir.kt
new file mode 100644
index 00000000000..195f5c0051b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromExtension.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+import kotlin.reflect.KFunction0
+
+class A {
+    class Nested
+}
+    
+fun A.main() {
+    ::Nested
+    val y = A::Nested
+    
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction0<A.Nested>>(y)
+}
+
+fun Int.main() {
+    ::Nested
+    val y = A::Nested
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction0<A.Nested>>(y)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromTopLevel.fir.kt
new file mode 100644
index 00000000000..42ce7b8d21c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/nestedConstructorFromTopLevel.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction0
+
+class A {
+    class Nested
+}
+
+fun main() {
+    val x = A::Nested
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KFunction0<A.Nested>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityLocalVsTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityLocalVsTopLevel.fir.kt
new file mode 100644
index 00000000000..77ed0bde41f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityLocalVsTopLevel.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+fun bar() = 42
+
+fun main() {
+    fun bar() = 239
+
+    ::bar
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsExtension.fir.kt
new file mode 100644
index 00000000000..f8cbe71c6b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsExtension.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KFunction1
+
+class A {
+    fun foo() = 42
+}
+
+fun A.foo() {}
+
+fun main() {
+    val x = A::foo
+
+    checkSubtype<KFunction1<A, Int>>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsTopLevel.fir.kt
new file mode 100644
index 00000000000..64caf41012d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsTopLevel.fir.kt
@@ -0,0 +1,31 @@
+// !CHECK_TYPE
+// !LANGUAGE: +CallableReferencesToClassMembersWithEmptyLHS
+
+import kotlin.reflect.KFunction0
+
+fun expectFunction0Unit(f: () -> Unit) = f
+fun expectFunction0String(f: () -> String) = f
+fun expectFunction1Unit(f: (A) -> Unit) = f
+fun expectFunction1String(f: (A) -> String) = f
+
+fun foo(): String = ""
+
+class A {
+    fun foo() {}
+    
+    fun main() {
+        val x = ::foo
+
+        checkSubtype<KFunction0<Unit>>(x)
+
+        expectFunction0Unit(x)
+        <!INAPPLICABLE_CANDIDATE!>expectFunction0String<!>(x)
+        <!INAPPLICABLE_CANDIDATE!>expectFunction1Unit<!>(x)
+        <!INAPPLICABLE_CANDIDATE!>expectFunction1String<!>(x)
+
+        expectFunction0Unit(::foo)
+        expectFunction0String(::foo)
+        <!INAPPLICABLE_CANDIDATE!>expectFunction1Unit<!>(::foo)
+        <!INAPPLICABLE_CANDIDATE!>expectFunction1String<!>(::foo)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/privateStaticAndPublicMember.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/privateStaticAndPublicMember.fir.kt
new file mode 100644
index 00000000000..4a1fcff935d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/privateStaticAndPublicMember.fir.kt
@@ -0,0 +1,10 @@
+// SKIP_TXT
+// FILE: A.java
+class A {
+    private static void foo() {}
+    public String foo(int x) {}
+}
+// FILE: main.kt
+fun main() {
+    (A::foo)(A(), 1)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/renameOnImport.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/renameOnImport.fir.kt
new file mode 100644
index 00000000000..24d48d3fff5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/renameOnImport.fir.kt
@@ -0,0 +1,30 @@
+// !CHECK_TYPE
+// FILE: a.kt
+
+package other
+
+fun foo() {}
+
+class A {
+    fun bar() = 42
+}
+
+fun A.baz(x: String) {}
+
+// FILE: b.kt
+
+import kotlin.reflect.*
+
+import other.foo as foofoo
+import other.A as AA
+import other.baz as bazbaz
+
+fun main() {
+    val x = ::foofoo
+    val y = AA::bar
+    val z = AA::bazbaz
+
+    checkSubtype<KFunction0<Unit>>(x)
+    checkSubtype<KFunction1<AA, Int>>(y)
+    checkSubtype<KFunction2<AA, String, Unit>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromClass.fir.kt
new file mode 100644
index 00000000000..957ac5d9a57
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromClass.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+fun foo() {}
+fun bar(x: Int) {}
+fun baz() = "OK"
+
+class A {
+    fun main() {
+        val x = ::foo
+        val y = ::bar
+        val z = ::baz
+
+        checkSubtype<KFunction0<Unit>>(x)
+        checkSubtype<KFunction1<Int, Unit>>(y)
+        checkSubtype<KFunction0<String>>(z)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromExtension.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromExtension.fir.kt
new file mode 100644
index 00000000000..6152a3cc17c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromExtension.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class A
+
+fun foo() {}
+fun bar(x: Int) {}
+fun baz() = "OK"
+
+fun A.main() {
+    val x = ::foo
+    val y = ::bar
+    val z = ::baz
+
+    checkSubtype<KFunction0<Unit>>(x)
+    checkSubtype<KFunction1<Int, Unit>>(y)
+    checkSubtype<KFunction0<String>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromExtensionInClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromExtensionInClass.fir.kt
new file mode 100644
index 00000000000..726176d3407
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromExtensionInClass.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class A
+
+fun foo() {}
+fun bar(x: Int) {}
+fun baz() = "OK"
+
+class B {
+    fun A.main() {
+        val x = ::foo
+        val y = ::bar
+        val z = ::baz
+
+        checkSubtype<KFunction0<Unit>>(x)
+        checkSubtype<KFunction1<Int, Unit>>(y)
+        checkSubtype<KFunction0<String>>(z)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromTopLevel.fir.kt
new file mode 100644
index 00000000000..b5a8194bacc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/topLevelFromTopLevel.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+fun foo() {}
+fun bar(x: Int) {}
+fun baz() = "OK"
+
+fun main() {
+    val x = ::foo
+    val y = ::bar
+    val z = ::baz
+
+    checkSubtype<KFunction0<Unit>>(x)
+    checkSubtype<KFunction1<Int, Unit>>(y)
+    checkSubtype<KFunction0<String>>(z)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/function/unresolved.fir.kt b/compiler/testData/diagnostics/tests/callableReference/function/unresolved.fir.kt
new file mode 100644
index 00000000000..d6e8601e7b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/function/unresolved.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION, -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+class A
+
+fun test1() {
+    val foo = ::foo
+
+    ::bar
+
+    A::bar
+
+    <!UNRESOLVED_REFERENCE!>B<!>::bar
+}
+
+fun test2() {
+    fun foo(x: Any) {}
+    fun foo() {}
+
+    <!UNRESOLVED_REFERENCE!>Unresolved<!>::foo
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(<!UNRESOLVED_REFERENCE!>Unresolved<!>::foo)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(<!UNRESOLVED_REFERENCE!>Unresolved<!>::unresolved)
+    ::unresolved
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/functionReferenceWithDefaultValueAsOtherFunctionType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/functionReferenceWithDefaultValueAsOtherFunctionType.fir.kt
new file mode 100644
index 00000000000..ed924b0da86
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/functionReferenceWithDefaultValueAsOtherFunctionType.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+
+fun foo(a: String, b: Int = 5): String {
+    return a + b
+}
+
+fun bar1(body: (String) -> String): String {
+    return body("something")
+}
+
+fun bar2(body: (String, Int) -> String): String {
+    return body("something", 0)
+}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>bar1<!>(::foo)
+    bar2(::foo)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/functionReferenceWithDefaultValueAsOtherFunctionType_enabled.fir.kt b/compiler/testData/diagnostics/tests/callableReference/functionReferenceWithDefaultValueAsOtherFunctionType_enabled.fir.kt
new file mode 100644
index 00000000000..f104ac67c15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/functionReferenceWithDefaultValueAsOtherFunctionType_enabled.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +NewInference +FunctionReferenceWithDefaultValueAsOtherType
+
+fun foo(a: String, b: Int = 5): String {
+    return a + b
+}
+
+fun bar1(body: (String) -> String): String {
+    return body("something")
+}
+
+fun bar2(body: (String, Int) -> String): String {
+    return body("something", 0)
+}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>bar1<!>(::foo)
+    bar2(::foo)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/argumentAndReturnExpectedType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/argumentAndReturnExpectedType.fir.kt
new file mode 100644
index 00000000000..c43049f5469
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/argumentAndReturnExpectedType.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+fun <T, R> foo(x: T): R = TODO()
+
+fun <T> fooReturnInt(x: T): Int = 1
+fun <T> fooTakeString(x: String): T = TODO()
+
+fun <T, R> bar(x: T, y: R, f: (T) -> R): Pair<T, R> = TODO()
+fun <T, R> baz(f: (T) -> R, g: (T) -> R): Pair<T, R> = TODO()
+
+class Pair<A, B>(val a: A, val b: B)
+
+fun test1() {
+    bar("", 1, ::foo).checkType { _<Pair<String, Int>>() }
+    bar("", 1, ::fooReturnInt).checkType { _<Pair<String, Int>>() }
+    bar("", 1, ::fooTakeString).checkType { _<Pair<String, Int>>() }
+    bar("", "", ::fooReturnInt).checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Pair<String, Any>>() }
+
+    val x: String = bar("", "", ::fooReturnInt)
+
+    baz(Int::toString, ::foo).checkType { _<Pair<Int, String>>() }
+}
+
+fun <T> listOf(): List<T> = TODO()
+fun <T> setOf(): Set<T> = TODO()
+
+fun <T> test2(x: T) {
+    bar(x, x, ::foo).checkType { _<Pair<T, T>>() }
+    bar(x, 1, ::foo).checkType { _<Pair<T, Int>>() }
+    bar(1, x, ::foo).checkType { _<Pair<Int, T>>() }
+
+    bar(listOf<T>(), setOf<T>(), ::foo).checkType { _<Pair<List<T>, Set<T>>> () }
+    bar(listOf<T>(), 1, ::foo).checkType { _<Pair<List<T>, Int>>() }
+    bar(1, listOf<T>(), ::foo).checkType { _<Pair<Int, List<T>>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/argumentExpectedType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/argumentExpectedType.fir.kt
new file mode 100644
index 00000000000..895abad9df6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/argumentExpectedType.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Case<T>
+fun <T> test(case: Case<T>) {}
+fun runTest(method: (Case<Any>) -> Unit) {}
+
+fun <T> runTestGeneric(f: (Case<T>) -> Unit) {}
+
+fun test() {
+    runTest(::test)
+    runTestGeneric<Int>(::test)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/dependOnArgumentType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/dependOnArgumentType.fir.kt
new file mode 100644
index 00000000000..44924ce85d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/dependOnArgumentType.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +SamConversionPerArgument +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A {
+    public static void invokeLater(Runnable doRun) {
+    }
+}
+
+// FILE: 1.kt
+
+fun <T> foo(t: T, x: (() -> Unit) -> Unit) {}
+
+fun <T> bar(s: T) {}
+fun <T> complex(t: T, f: (T) -> Unit) {}
+
+fun test1() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, A::invokeLater) // KT-24507 SAM conversion accidentally applied to callable reference and incorrectly handled via BE
+    foo(1, ::bar)
+
+    complex(1, ::bar)
+}
+
+fun <R> test2(x: R) {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(x, A::invokeLater) // KT-24507 SAM conversion accidentally applied to callable reference and incorrectly handled via BE
+    foo(x, ::bar)
+
+    complex(x, ::bar)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/expectedFunctionType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/expectedFunctionType.fir.kt
new file mode 100644
index 00000000000..f4b473683e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/expectedFunctionType.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A1 {
+    fun <T> a1(t: T): Unit {}
+    fun test1(): (String) -> Unit = A1()::a1
+}
+
+class A2 {
+    fun <K, V> a2(key: K): V = TODO()
+
+    fun test1(): (String) -> Unit = A2()::a2
+    fun <T3> test2(): (T3) -> T3 = A2()::a2
+}
+
+class A3<T> {
+    fun <V> a3(key: T): V = TODO()
+
+    fun test1(): (T) -> Int = this::a3
+    fun test2(): (T) -> Unit = A3<T>()::a3
+    fun test3(): (Int) -> String = A3<Int>()::a3
+
+    fun <R> test4(): (R) -> Unit = this::a3
+    fun <R> test5(): (T) -> R = this::a3
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/explicitTypeArguments.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/explicitTypeArguments.fir.kt
new file mode 100644
index 00000000000..2806859ae53
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/explicitTypeArguments.fir.kt
@@ -0,0 +1,25 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+fun <T> takeFun(f: (T) -> Unit) {}
+fun <T, R> callFun(f: (T) -> R): R = TODO()
+
+fun <T> foo(s: T) {}
+fun <T : Int> fooInt(s: T) {}
+
+open class Wrapper<T>(val value: T)
+fun <T, R : Wrapper<in T>> createWrapper(s: T): R = TODO()
+
+fun <T> Wrapper<T>.baz(transform: (T) -> Unit): T = TODO()
+
+fun test() {
+    takeFun<String>(::foo)
+    <!INAPPLICABLE_CANDIDATE!>takeFun<!><String>(::fooInt)
+
+    callFun<String, Wrapper<String>>(::createWrapper)
+    callFun<Int, Wrapper<Number>>(::createWrapper)
+    callFun<String, Wrapper<*>>(::createWrapper)
+    callFun<String, Wrapper<Int>>(::createWrapper)
+
+    callFun<Int, Wrapper<Int>>(::createWrapper).baz(::foo)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/genericExtensionFunction.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/genericExtensionFunction.fir.kt
new file mode 100644
index 00000000000..b2d645d4c59
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/genericExtensionFunction.fir.kt
@@ -0,0 +1,31 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+class Wrapper
+
+fun <R, S> Wrapper.foo(x: R): S = TODO()
+fun Wrapper.fooIntString(x: Int): String = ""
+fun <T> Wrapper.fooReturnString(x: T): String = ""
+fun <T> Wrapper.fooTakeInt(x: Int): T = TODO()
+
+fun <T, R, S> bar(f: T.(R) -> S): Tripple<T, R, S> = TODO()
+fun <T, R, S> baz(x: T, y: R, z: S, f: T.(R) -> S): Tripple<T, R, S> = TODO()
+
+class Tripple<A, B, C>(val a: A, val b: B, val c: C)
+
+fun test1() {
+    val x: Wrapper.(String) -> Boolean = Wrapper::foo
+    bar<Wrapper, Double, Float>(Wrapper::foo).checkType { _<Tripple<Wrapper, Double, Float>>() }
+    bar(Wrapper::fooIntString).checkType { _<Tripple<Wrapper, Int, String>>() }
+}
+
+fun <T> test2() {
+    bar<Wrapper, Int, String>(Wrapper::fooReturnString).checkType { _<Tripple<Wrapper, Int, String>>() }
+    bar<Wrapper, T, String>(Wrapper::fooReturnString).checkType { _<Tripple<Wrapper, T, String>>() }
+    <!INAPPLICABLE_CANDIDATE!>bar<!><Wrapper, T, T>(Wrapper::fooReturnString)
+    <!INAPPLICABLE_CANDIDATE!>bar<!><Wrapper, Int, Int>(Wrapper::fooReturnString)
+
+    bar<Wrapper, Int, T>(Wrapper::fooTakeInt).checkType { _<Tripple<Wrapper, Int, T>>() }
+    bar<Wrapper, Int, String>(Wrapper::fooTakeInt).checkType { _<Tripple<Wrapper, Int, String>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/genericFunctionsWithNullableTypes.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/genericFunctionsWithNullableTypes.fir.kt
new file mode 100644
index 00000000000..33c47530fce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/genericFunctionsWithNullableTypes.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+fun <T, R> foo(x: T): R = TODO()
+fun <T, R> bar(x: T, y: R, f: (T) -> R): Pair<T, R?> = TODO()
+
+inline fun <reified T, reified R> baz(x: T, y: R, f: (T) -> R) {}
+
+data class Pair<A, B>(val a: A, val b: B)
+
+fun <T> test(x: T) {
+    bar(1, "", ::foo).checkType { _<Pair<Int, String?>>() }
+    bar(null, "", ::foo).checkType { _<Pair<Nothing?, String?>>() }
+    bar(1, null, ::foo).checkType { _<Pair<Int, Nothing?>>() }
+    bar(null, null, ::foo).checkType { _<Pair<Nothing?, Nothing?>>() }
+    bar(1, x, ::foo).checkType { _<Pair<Int, T?>>() }
+
+    val s1: Pair<Int, String?> = bar(1, "", ::foo)
+    val (a: Int, b: String?) = bar(1, "", ::foo)
+
+    val s2: Pair<Int?, String?> = bar(null, null, ::foo)
+
+    baz<Int?, String?>(null, null, ::foo)
+
+    baz<Int, String?>(null, null, ::foo)
+    baz<Int?, String>(null, null, ::foo)
+    baz(null, "", ::foo)
+    baz(1, null, ::foo)
+    baz(null, null, ::foo)
+
+    val s3: Pair<Int, String?> = bar(null, null, ::foo)
+    val s4: Pair<Int?, String> = bar(null, null, ::foo)
+
+    val s5: Pair<Int, String> = bar(1, "", ::foo)
+    val (a1: Int, b1: String) = bar(1, "", ::foo)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/kt10968.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/kt10968.fir.kt
new file mode 100644
index 00000000000..fa82df7a68f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/kt10968.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// KT-10968 Callable reference: type inference by function return type
+
+fun <T> getT(): T = null!!
+
+fun getString() = ""
+
+fun test() {
+    val a : () -> String = ::getString
+    val b : () -> String = ::getT
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/kt11075.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/kt11075.fir.kt
new file mode 100644
index 00000000000..eca63b0f1d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/kt11075.fir.kt
@@ -0,0 +1,10 @@
+// KT-11075 NONE_APPLICABLE reported for callable reference to an overloaded generic function with expected type provided
+
+object TestCallableReferences {
+    fun <A> foo(x: A) = x
+    fun <B> foo(x: List<B>) = x
+
+    fun test0(): (String) -> String = TestCallableReferences::foo
+
+    fun <T> test1(): (List<T>) -> List<T> = <!UNRESOLVED_REFERENCE!>TestCallableReferences::foo<!>
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/kt12286.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/kt12286.fir.kt
new file mode 100644
index 00000000000..2286bb05bcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/kt12286.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// KT-12286 Strange type is required for generic callable reference
+
+fun <T: Comparable<T>> maxOf(a: T, b: T): T = if (a < b) b else a
+
+fun <T: Comparable<T>> useMaxOf() {
+    val f: (T, T) -> T = ::maxOf
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/kt7470.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/kt7470.fir.kt
new file mode 100644
index 00000000000..8a20367ae65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/kt7470.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+
+fun <T> shuffle(x: List<T>): List<T> = x
+
+fun bar() {
+    val s: (List<String>) -> List<String> = ::shuffle
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/nestedCallWithOverload.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/nestedCallWithOverload.fir.kt
new file mode 100644
index 00000000000..20c94cb3ae6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/nestedCallWithOverload.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+fun foo(i: Int) {}
+fun foo(s: String) {}
+fun <T> id(x: T): T = x
+fun <T> baz(x: T, y: T): T = TODO()
+
+fun test() {
+    val x1: (Int) -> Unit = id(id(::foo))
+    val x2: (Int) -> Unit = baz(id(::foo), ::foo)
+    val x3: (Int) -> Unit = baz(id(::foo), id(id(::foo)))
+    val x4: (String) -> Unit = baz(id(::foo), id(id(::foo)))
+    val x5: (Double) -> Unit = baz(id(<!UNRESOLVED_REFERENCE!>::foo<!>), id(id(<!UNRESOLVED_REFERENCE!>::foo<!>)))
+
+
+    id<(Int) -> Unit>(id(id(<!UNRESOLVED_REFERENCE!>::foo<!>)))
+    id(id<(Int) -> Unit>(::foo))
+    baz<(Int) -> Unit>(id(<!UNRESOLVED_REFERENCE!>::foo<!>), id(id(<!UNRESOLVED_REFERENCE!>::foo<!>)))
+    baz(id(<!UNRESOLVED_REFERENCE!>::foo<!>), id(id<(Int) -> Unit>(::foo)))
+    baz(id(<!UNRESOLVED_REFERENCE!>::foo<!>), id<(Int) -> Unit>(id(::foo)))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/noInferenceFeatureForCallableReferences.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/noInferenceFeatureForCallableReferences.fir.kt
new file mode 100644
index 00000000000..76f8bdfc56b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/noInferenceFeatureForCallableReferences.fir.kt
@@ -0,0 +1,67 @@
+// !LANGUAGE: -TypeInferenceOnGenericsForCallableReferences
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+fun <T> bar(s: T) {}
+fun <T> complex(t: T, f: (T) -> Unit) {}
+fun <T> simple(f: (T) -> Unit) {}
+
+fun test1() {
+    complex(1, ::bar)
+    simple<String>(::bar)
+}
+
+// ---
+
+fun <T> takeFun(f: (T) -> Unit) {}
+fun <T, R> callFun(f: (T) -> R): R = TODO()
+
+fun <T> foo(s: T) {}
+
+open class Wrapper<T>(val value: T)
+fun <T, R : Wrapper<in T>> createWrapper(s: T): R = TODO()
+
+fun <T> Wrapper<T>.baz(transform: (T) -> Unit): T = TODO()
+
+fun test2() {
+    takeFun<String>(::foo)
+
+    callFun<String, Wrapper<String>>(::createWrapper)
+    callFun<Int, Wrapper<Number>>(::createWrapper)
+    callFun<String, Wrapper<*>>(::createWrapper)
+
+    callFun<Int, Wrapper<Int>>(::createWrapper).baz(::foo)
+}
+
+// ---
+
+fun test3() {
+    val a1: Array<Double.(Double) -> Double> = arrayOf(Double::plus, Double::minus)
+    val a2: Array<Double.(Int) -> Double> = arrayOf(Double::plus, Double::minus)
+}
+
+// ---
+
+class A1 {
+    fun <T> a1(t: T): Unit {}
+    fun test1(): (String) -> Unit = A1()::a1
+}
+
+class A2 {
+    fun <K, V> a2(key: K): V = TODO()
+
+    fun test1(): (String) -> Unit = A2()::a2
+    fun <T3> test2(): (T3) -> T3 = A2()::a2
+}
+
+// ---
+
+fun foo1(x: Int?) {}
+fun foo1(y: String?) {}
+fun foo1(z: Boolean) {}
+
+fun <T> baz1(element: (T) -> Unit): T? = null
+
+fun test4() {
+    val a1: Int? = baz1(::foo1)
+    val a2: String? = baz1(::foo1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/resolutionGenericCallableWithNullableTypes.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/resolutionGenericCallableWithNullableTypes.fir.kt
new file mode 100644
index 00000000000..1d1c41ecace
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/resolutionGenericCallableWithNullableTypes.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+fun foo(x: Int?) {}
+fun foo(y: String?) {}
+fun foo(z: Boolean) {}
+
+fun <T> baz(element: (T) -> Unit): T? = null
+
+fun test1() {
+    val a1: Int? = baz(::foo)
+    val a2: String? = baz(::foo)
+    val a3: Boolean? = baz<Boolean>(::foo)
+
+    baz<Int>(::foo).checkType { _<Int?>() }
+    baz<String>(::foo).checkType { _<String?>() }
+    baz<Boolean>(::foo).checkType { _<Boolean?>() }
+
+    val b1: Int = baz(<!UNRESOLVED_REFERENCE!>::foo<!>)
+    val b2: String = baz(<!UNRESOLVED_REFERENCE!>::foo<!>)
+    val b3: Boolean = baz(<!UNRESOLVED_REFERENCE!>::foo<!>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/resolutionWithGenericCallable.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/resolutionWithGenericCallable.fir.kt
new file mode 100644
index 00000000000..f5d5de415b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/resolutionWithGenericCallable.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+fun test() {
+    val a1: Array<Double.(Double) -> Double> = arrayOf(Double::plus, Double::minus)
+    val a2: Array<Double.(Int) -> Double> = arrayOf(Double::plus, Double::minus)
+
+    val a3: Array<Int.(Int) -> Double> = arrayOf(<!UNRESOLVED_REFERENCE!>Double::plus<!>, <!UNRESOLVED_REFERENCE!>Double::minus<!>)
+    val a4: Array<Int.(Double) -> Double> = arrayOf(Int::plus, <!UNRESOLVED_REFERENCE!>Double::minus<!>)
+    val a5: Array<Double.(Double) -> Double> = arrayOf(Double::plus, <!UNRESOLVED_REFERENCE!>Int::minus<!>)
+}
+
+fun foo(x: Int) {}
+fun foo(y: String) {}
+
+fun <T> bar(x: T, f: (T) -> Unit) {}
+
+fun test2() {
+    bar(1, ::foo)
+    bar("", ::foo)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(1.0, <!UNRESOLVED_REFERENCE!>::foo<!>)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/generic/specialCalls.fir.kt b/compiler/testData/diagnostics/tests/callableReference/generic/specialCalls.fir.kt
new file mode 100644
index 00000000000..1d2645d1bfc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/generic/specialCalls.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+fun baz(i: Int) = i
+fun <T> bar(x: T): T = TODO()
+
+fun nullableFun(): ((Int) -> Int)? = null
+
+fun test() {
+    val x1: (Int) -> Int = bar(if (true) <!UNRESOLVED_REFERENCE!>::baz<!> else <!UNRESOLVED_REFERENCE!>::baz<!>)
+    val x2: (Int) -> Int = bar(nullableFun() ?: <!UNRESOLVED_REFERENCE!>::baz<!>)
+    val x3: (Int) -> Int = bar(::baz ?: <!UNRESOLVED_REFERENCE!>::baz<!>)
+
+    val i = 0
+    val x4: (Int) -> Int = bar(when (i) {
+                                   10 -> <!UNRESOLVED_REFERENCE!>::baz<!>
+                                   20 -> <!UNRESOLVED_REFERENCE!>::baz<!>
+                                   else -> <!UNRESOLVED_REFERENCE!>::baz<!>
+                               })
+
+    val x5: (Int) -> Int = bar(<!UNRESOLVED_REFERENCE!>::baz<!>!!)
+
+    <!UNRESOLVED_REFERENCE!>(if (true) <!UNRESOLVED_REFERENCE!>::baz<!> else <!UNRESOLVED_REFERENCE!>::baz<!>)(1)<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/kt15439_completeCall.fir.kt b/compiler/testData/diagnostics/tests/callableReference/kt15439_completeCall.fir.kt
new file mode 100644
index 00000000000..d684aa7cc51
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/kt15439_completeCall.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_VARIABLE
+
+fun test() {
+    data class Pair<F, S>(val first: F, val second: S)
+    val (x, y) =
+            Pair(1,
+                 if (1 == 1)
+                     <!UNRESOLVED_REFERENCE!>Pair<String, String>::first<!>
+                 else
+                     <!UNRESOLVED_REFERENCE!>Pair<String, String>::second<!>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/kt25433.fir.kt b/compiler/testData/diagnostics/tests/callableReference/kt25433.fir.kt
new file mode 100644
index 00000000000..b9a172d117d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/kt25433.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// Issue: KT-25433
+
+import kotlin.reflect.*
+
+fun <T, R> hidden(nameProp: KProperty1<T, R>, value: R) {}
+fun <T, R> hiddenFun(nameFunc: KFunction1<T, R>, value: R) {}
+
+class App(val nullable: String?) {
+    fun nullableFun(): String? = null
+}
+
+fun test() {
+    hidden(App::nullable, "foo")
+    hiddenFun(App::nullableFun, "foo")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/kt31981.fir.kt b/compiler/testData/diagnostics/tests/callableReference/kt31981.fir.kt
new file mode 100644
index 00000000000..7c4da22aba5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/kt31981.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty1
+import kotlin.reflect.KMutableProperty1
+
+class Inv<T> {
+    val size: Int = 0
+}
+
+class DTO<T> {
+    val test: Inv<T>? = null
+    var q: Int = 0
+    operator fun <R> get(prop: KProperty1<*, R>): R = TODO()
+    operator fun <R> set(prop: KMutableProperty1<*, R>, value: R) { }
+}
+
+fun main(intDTO: DTO<Int>?) {
+    if (intDTO != null) {
+        intDTO[DTO<Int>::q] = intDTO[DTO<Int>::test]!!.size
+        intDTO[DTO<Int>::q] = intDTO[DTO<Int>::test]!!.size
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/kt32256.fir.kt b/compiler/testData/diagnostics/tests/callableReference/kt32256.fir.kt
new file mode 100644
index 00000000000..09de610906f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/kt32256.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// Issue: KT-32256
+
+fun main() {
+    myMethod(::refA)
+    myMethod(::refB)
+    anotherMethod(::refA)
+    anotherMethod(::refB)
+}
+
+suspend fun refA(input: String): String {
+    return input
+}
+
+suspend fun refB(): String {
+    return "Hello, World!"
+}
+
+fun myMethod(f: suspend (String) -> String) {}
+
+fun myMethod(f: suspend () -> String) {}
+
+fun <I, O> anotherMethod(f: suspend (I) -> O) {}
+
+fun <O> anotherMethod(f: suspend () -> O) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/kt7430_wrongClassOnLHS.fir.kt b/compiler/testData/diagnostics/tests/callableReference/kt7430_wrongClassOnLHS.fir.kt
new file mode 100644
index 00000000000..bcf23b25647
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/kt7430_wrongClassOnLHS.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+class Unrelated()
+
+class Test(val name: String = "") {
+    init {
+        Unrelated::name
+        Unrelated::foo
+    }
+
+    fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/memberExtensionsImportedFromObjectsUnsupported.fir.kt b/compiler/testData/diagnostics/tests/callableReference/memberExtensionsImportedFromObjectsUnsupported.fir.kt
new file mode 100644
index 00000000000..acee4e1fb1d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/memberExtensionsImportedFromObjectsUnsupported.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+import Obj.ext
+import A.Companion.ext2
+
+object Obj {
+    val String.ext: String get() = this
+}
+
+class A {
+    companion object {
+        val String.ext2: String get() = this
+    }
+}
+
+fun test() {
+    String::ext
+    Obj::ext
+
+    String::ext2
+    A.Companion::ext2
+    A::ext2
+
+    A::foo
+    A::bar
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/noExceptionOnRedCodeWithArrayLikeCall.fir.kt b/compiler/testData/diagnostics/tests/callableReference/noExceptionOnRedCodeWithArrayLikeCall.fir.kt
new file mode 100644
index 00000000000..02ada4d5b93
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/noExceptionOnRedCodeWithArrayLikeCall.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +NewInference
+
+class DTO {
+    val q: Int = 0
+    operator fun get(prop: KProperty1<*, Int>): Int = 0
+}
+
+fun foo(intDTO: DTO?, p: KProperty1<*, Int>) {
+    if (intDTO != null) {
+        intDTO[DTO::q]
+        intDTO.q
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/packageInLhs.fir.kt b/compiler/testData/diagnostics/tests/callableReference/packageInLhs.fir.kt
new file mode 100644
index 00000000000..9a280b8ae57
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/packageInLhs.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// FILE: simpleName.kt
+
+package foo
+
+fun test() {
+    foo::test
+}
+
+// FILE: qualifiedName.kt
+
+package foo.bar
+
+fun test() {
+    foo.bar::test
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/parsingPriorityOfGenericArgumentsVsLess.fir.kt b/compiler/testData/diagnostics/tests/callableReference/parsingPriorityOfGenericArgumentsVsLess.fir.kt
new file mode 100644
index 00000000000..9525642a22c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/parsingPriorityOfGenericArgumentsVsLess.fir.kt
@@ -0,0 +1,9 @@
+package test
+
+class Foo {
+    fun <T> bar(x: Int) = x
+}
+
+fun test() {
+    Foo::bar <!SYNTAX!>< Int ><!> <!SYNTAX!>(2 + 2)<!>
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/abstractPropertyViaSubclasses.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/abstractPropertyViaSubclasses.fir.kt
new file mode 100644
index 00000000000..4a0a3b0b4c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/abstractPropertyViaSubclasses.fir.kt
@@ -0,0 +1,36 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KProperty1
+
+interface Base {
+    val x: Any
+}
+
+class A : Base {
+    override val x: String = ""
+}
+
+open class B : Base {
+    override val x: Number = 1.0
+}
+
+class C : B() {
+    override val x: Int = 42
+}
+
+fun test() {
+    val base = Base::x
+    checkSubtype<KProperty1<Base, Any>>(base)
+    checkSubtype<Any>(base.get(A()))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Number>(base.get(B()))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(base.get(C()))
+
+    val a = A::x
+    checkSubtype<KProperty1<A, String>>(a)
+    checkSubtype<String>(a.get(A()))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Number>(a.<!INAPPLICABLE_CANDIDATE!>get<!>(B()))
+
+    val b = B::x
+    checkSubtype<KProperty1<B, Number>>(b)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(b.get(C()))
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/accessViaSubclass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/accessViaSubclass.fir.kt
new file mode 100644
index 00000000000..ec5c86975b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/accessViaSubclass.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KProperty1
+
+open class Base {
+    val foo: Int = 42
+}
+
+open class Derived : Base()
+
+fun test() {
+    val o = Base::foo
+    checkSubtype<KProperty1<Base, Int>>(o)
+    checkSubtype<Int>(o.get(Derived()))
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/classFromClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/classFromClass.fir.kt
new file mode 100644
index 00000000000..8630be83473
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/classFromClass.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS:-UNUSED_VARIABLE
+
+import kotlin.reflect.*
+
+class A(var g: A) {
+    val f: Int = 0
+
+    fun test() {
+        val fRef: KProperty1<A, Int> = A::f
+        val gRef: KMutableProperty1<A, A> = A::g
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/extensionFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/extensionFromTopLevel.fir.kt
new file mode 100644
index 00000000000..de71e04316b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/extensionFromTopLevel.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+val String.countCharacters: Int
+    get() = length
+
+var Int.meaning: Long
+    get() = 42L
+    set(value) {}
+
+fun test() {
+    val f = String::countCharacters
+    
+    checkSubtype<KProperty1<String, Int>>(f)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KMutableProperty1<String, Int>>(f)
+    checkSubtype<Int>(f.get("abc"))
+    f.<!UNRESOLVED_REFERENCE!>set<!>("abc", 0)
+
+    val g = Int::meaning
+
+    checkSubtype<KMutableProperty1<Int, Long>>(g)
+    checkSubtype<Long>(g.get(0))
+    g.set(1, 0L)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/extensionPropertyOnNullable.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/extensionPropertyOnNullable.fir.kt
new file mode 100644
index 00000000000..ac0014dd549
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/extensionPropertyOnNullable.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+val Any?.meaning: Int
+    get() = 42
+
+fun test() {
+    val f = Any?::meaning
+    checkSubtype<Int>(f.get(null))
+    checkSubtype<Int>(f.get(""))
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/genericClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/genericClass.fir.kt
new file mode 100644
index 00000000000..709df31402c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/genericClass.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KProperty1
+
+class A<T>(val t: T) {
+    val foo: T = t
+}
+
+fun bar() {
+    val x = A<String>::foo
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KProperty1<A<String>, String>>(x)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KProperty1<A<String>, Any?>>(x)
+
+    val y = A<*>::foo
+    checkSubtype<KProperty1<A<*>, Any?>>(y)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/javaInstanceField.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/javaInstanceField.fir.kt
new file mode 100644
index 00000000000..a5f8a33c53a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/javaInstanceField.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS:-UNUSED_VARIABLE
+// FILE: JavaClass.java
+
+public class JavaClass {
+    public final int publicFinal;
+    public long publicMutable;
+
+    protected final double protectedFinal;
+    protected char protectedMutable;
+
+    private final String privateFinal;
+    private Object privateMutable;
+}
+
+// FILE: test.kt
+
+import kotlin.reflect.*
+
+fun test() {
+    val pubFinRef: KProperty1<JavaClass, Int> = JavaClass::publicFinal
+    val pubMutRef: KMutableProperty1<JavaClass, Long> = JavaClass::publicMutable
+    val protFinRef: KProperty1<JavaClass, Double> = JavaClass::protectedFinal
+    val protMutRef: KMutableProperty1<JavaClass, Char> = JavaClass::protectedMutable
+    val privFinRef: KProperty1<JavaClass, String?> = JavaClass::privateFinal
+    val privMutRef: KMutableProperty1<JavaClass, Any?> = JavaClass::privateMutable
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/javaStaticFieldViaImport.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/javaStaticFieldViaImport.fir.kt
new file mode 100644
index 00000000000..48a363f78fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/javaStaticFieldViaImport.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS:-UNUSED_VARIABLE
+// FILE: JavaClass.java
+
+public class JavaClass {
+    public static final String publicFinal;
+    public static volatile Object publicMutable;
+
+    protected static final double protectedFinal;
+    protected static char protectedMutable;
+
+    private static final JavaClass privateFinal;
+    private static Throwable privateMutable;
+}
+
+// FILE: test.kt
+
+import JavaClass.*
+
+import kotlin.reflect.*
+
+fun test() {
+    val pubFinRef: KProperty0<String> = ::publicFinal
+    val pubMutRef: KMutableProperty0<Any?> = ::publicMutable
+    val protFinRef: KProperty<Double> = ::protectedFinal
+    val protMutRef: KMutableProperty<Char> = ::protectedMutable
+    val privFinRef: KProperty<JavaClass?> = ::privateFinal
+    val privMutRef: KMutableProperty<Throwable?> = ::privateMutable
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/kt7564.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/kt7564.fir.kt
new file mode 100644
index 00000000000..0be4a663de9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/kt7564.fir.kt
@@ -0,0 +1,12 @@
+import kotlin.reflect.*
+
+fun <T> checkSubtype(t: T) = t
+
+class A(var g: A) {
+    val f: Int = 0
+
+    fun test() {
+        checkSubtype<KProperty1<A, Int>>(A::f)
+        checkSubtype<KMutableProperty1<A, A>>(A::g)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/kt7945_unrelatedClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/kt7945_unrelatedClass.fir.kt
new file mode 100644
index 00000000000..719be10b741
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/kt7945_unrelatedClass.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty1
+
+class TestClass(var prop: Int)
+open class OtherClass
+fun OtherClass.test(prop: KProperty1<TestClass, Int>): Unit = throw Exception()
+class OtherClass2: OtherClass() {
+    val result = <!INAPPLICABLE_CANDIDATE!>test<!>(TestClass::result)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/localVariable.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/localVariable.fir.kt
new file mode 100644
index 00000000000..c170c78a97a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/localVariable.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun eat(value: Any) {}
+
+fun test(param: String) {
+    val a = ::param
+
+    val local = "local"
+    val b = ::local
+
+    val lambda = { -> }
+    val g = ::lambda
+
+    eat(::param)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/memberFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/memberFromTopLevel.fir.kt
new file mode 100644
index 00000000000..09e82f8d23d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/memberFromTopLevel.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+class A {
+    val foo: Int = 42
+    var bar: String = ""
+}
+
+fun test() {
+    val p = A::foo
+
+    checkSubtype<KProperty1<A, Int>>(p)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KMutableProperty1<A, Int>>(p)
+    checkSubtype<Int>(p.get(A()))
+    p.<!INAPPLICABLE_CANDIDATE!>get<!>()
+    p.<!UNRESOLVED_REFERENCE!>set<!>(A(), 239)
+
+    val q = A::bar
+
+    checkSubtype<KProperty1<A, String>>(q)
+    checkSubtype<KMutableProperty1<A, String>>(q)
+    checkSubtype<String>(q.get(A()))
+    q.set(A(), "q")
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/protectedVarFromClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/protectedVarFromClass.fir.kt
new file mode 100644
index 00000000000..b63c2baea8f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/protectedVarFromClass.fir.kt
@@ -0,0 +1,22 @@
+// KT-12982 Incorrect type inference when accessing mutable protected property via reflection
+
+import kotlin.reflect.KMutableProperty1
+
+class Foo {
+    protected var x = 0
+
+    fun baz(p: KMutableProperty1<Foo, Int>) = p
+    fun print() = baz(Foo::x)
+}
+
+
+open class A {
+    protected fun a() {}
+}
+
+open class B : A() {
+    val x = C::a
+    val y = C()::a
+}
+
+class C : B()
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/returnTypeDependentOnGenericProperty.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/returnTypeDependentOnGenericProperty.fir.kt
new file mode 100644
index 00000000000..4cae96f7f07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/returnTypeDependentOnGenericProperty.fir.kt
@@ -0,0 +1,8 @@
+import kotlin.reflect.KProperty1
+
+fun <T, R> getProperty(x: T, property: KProperty1<T, R>): R =
+        property.get(x)
+
+class Person(val name: String)
+
+val name1 = getProperty(Person("John Smith"), Person::name)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/samePriorityForFunctionsAndProperties.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/samePriorityForFunctionsAndProperties.fir.kt
new file mode 100644
index 00000000000..218a2795117
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/samePriorityForFunctionsAndProperties.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KProperty1
+
+class C {
+    val baz: Int = 12
+}
+
+fun Int.baz() {}
+
+fun test() {
+    C::baz checkType { <!UNRESOLVED_REFERENCE!>_<!><KProperty1<C, Int>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/syntheticProperties.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/syntheticProperties.fir.kt
new file mode 100644
index 00000000000..1fd83f1c2a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/syntheticProperties.fir.kt
@@ -0,0 +1,19 @@
+// FILE: Customer.java
+public class Customer {
+    private String name;
+
+    public Customer(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}
+
+// FILE: test.kt
+val customerName = Customer::name
diff --git a/compiler/testData/diagnostics/tests/callableReference/property/topLevelFromTopLevel.fir.kt b/compiler/testData/diagnostics/tests/callableReference/property/topLevelFromTopLevel.fir.kt
new file mode 100644
index 00000000000..cff6bfaaf0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/property/topLevelFromTopLevel.fir.kt
@@ -0,0 +1,32 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.*
+
+var x: Int = 42
+val y: String get() = "y"
+
+fun testX() {
+    val xx = ::x
+    checkSubtype<KMutableProperty0<Int>>(xx)
+    checkSubtype<KProperty0<Int>>(xx)
+    checkSubtype<KMutableProperty<Int>>(xx)
+    checkSubtype<KProperty<Int>>(xx)
+    checkSubtype<KCallable<Int>>(xx)
+
+    checkSubtype<String>(xx.name)
+    checkSubtype<Int>(xx.get())
+    xx.set(239)
+}
+
+fun testY() {
+    val yy = ::y
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KMutableProperty0<String>>(yy)
+    checkSubtype<KProperty0<String>>(yy)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><KMutableProperty<String>>(yy)
+    checkSubtype<KProperty<String>>(yy)
+    checkSubtype<KCallable<String>>(yy)
+
+    checkSubtype<String>(yy.name)
+    checkSubtype<String>(yy.get())
+    yy.<!UNRESOLVED_REFERENCE!>set<!>("yy")
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/propertyOfNestedGenericClass.fir.kt b/compiler/testData/diagnostics/tests/callableReference/propertyOfNestedGenericClass.fir.kt
new file mode 100644
index 00000000000..7d7c8a4353d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/propertyOfNestedGenericClass.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION -UNUSED_VARIABLE
+
+import kotlin.reflect.KProperty1
+
+class Scope {
+    abstract class Nested<T> {
+        abstract val key: Int
+        abstract val keyT: T
+    }
+}
+
+fun simple(a: Any?) {}
+fun <K> id(x: K): K = x
+
+fun test() {
+    simple(Scope.Nested<String>::key)
+    val a = id(Scope.Nested<String>::keyT)
+
+    a
+
+    val b = id(Scope.Nested<*>::keyT)
+
+    b
+
+    val c = id(Scope.Nested<out Number?>::keyT)
+
+    c
+
+    val d = id(Scope.Nested<*>::keyT as Scope.Nested<Number>)
+
+    d
+
+    val g = id<KProperty1<Scope.Nested<*>, Any?>>(Scope.Nested<*>::keyT)
+
+    g
+}
+
+fun justResolve() {
+    val a = Scope.Nested<String>::key
+    val b = Scope.Nested<String>::keyT
+    val c = Scope.Nested<*>::keyT
+    val d = Scope.Nested<out Number?>::keyT
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/ambiguityWhenNoApplicableCallableReferenceCandidate.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/ambiguityWhenNoApplicableCallableReferenceCandidate.fir.kt
new file mode 100644
index 00000000000..42cc26544a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/ambiguityWhenNoApplicableCallableReferenceCandidate.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(x: Int) {}
+fun foo(y: String) {}
+
+fun <T> bar(f: (T) -> Unit) {}
+
+fun test() {
+    bar(<!UNRESOLVED_REFERENCE!>::foo<!>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/ambiguousWithVararg.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/ambiguousWithVararg.fir.kt
new file mode 100644
index 00000000000..ba5ac78cc8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/ambiguousWithVararg.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun fun1() {}
+fun fun1(x: Int) {}
+
+val ref1 = <!UNRESOLVED_REFERENCE!>::fun1<!>
+
+fun fun2(vararg x: Int) {}
+fun fun2(x: Int) {}
+
+val ref2 = <!UNRESOLVED_REFERENCE!>::fun2<!>
+
+fun fun3(x0: Int, vararg xs: Int) {}
+fun fun3(x0: String, vararg xs: String) {}
+
+val ref3 = <!UNRESOLVED_REFERENCE!>::fun3<!>
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/applicableCallableReferenceFromDistantScope.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/applicableCallableReferenceFromDistantScope.fir.kt
new file mode 100644
index 00000000000..55fa377705e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/applicableCallableReferenceFromDistantScope.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun foo(s: String) {}
+
+object Scope {
+    fun foo(a: Int) {}
+    fun foo(b: Boolean) {}
+
+    fun <T> bar(f: (T) -> Unit): T = TODO()
+
+    fun test() {
+        val s: String = bar(::foo)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/byArgType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/byArgType.fir.kt
new file mode 100644
index 00000000000..bcae8c1979b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/byArgType.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo() {}
+fun foo(s: String) {}
+
+fun fn(f: () -> Unit) {}
+
+fun test() {
+    fn(::foo)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/byGenericArgType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/byGenericArgType.fir.kt
new file mode 100644
index 00000000000..94b5a42062c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/byGenericArgType.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> ofType(x: T): T = x
+
+fun foo() {}
+fun foo(s: String) {}
+
+val x1 = ofType<() -> Unit>(::foo)
+val x2 = ofType<(String) -> Unit>(::foo)
+val x3 = <!INAPPLICABLE_CANDIDATE!>ofType<!><(Int) -> Unit>(<!UNRESOLVED_REFERENCE!>::foo<!>)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/byValType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/byValType.fir.kt
new file mode 100644
index 00000000000..1ce622c783a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/byValType.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo() {}
+fun foo(s: String) {}
+
+val x1 = <!UNRESOLVED_REFERENCE!>::foo<!>
+val x2: () -> Unit = ::foo
+val x3: (String) -> Unit = ::foo
+val x4: (Int) -> Unit = <!UNRESOLVED_REFERENCE!>::foo<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/chooseCallableReferenceDependingOnInferredReceiver.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/chooseCallableReferenceDependingOnInferredReceiver.fir.kt
new file mode 100644
index 00000000000..04df73cbe96
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/chooseCallableReferenceDependingOnInferredReceiver.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -UNUSED_EXPRESSION
+
+class A {
+    fun foo(i: A) {}
+
+    fun baz(i: A) {}
+}
+
+class B {
+    fun foo(s: B) {}
+    fun foo(c: Char) {}
+
+    fun baz(s: B) {}
+}
+
+fun <T> bar(f: (T) -> Unit): T = TODO()
+
+fun test() {
+    myWith(A()) {
+        val t1 = bar(::foo)
+        t1
+
+        val t2 = bar(::baz)
+        t2
+
+        myWith(B()) {
+            val a: A = bar(::foo)
+            val b: B = bar(::foo)
+
+            val t3 = bar(::baz)
+            t3
+
+            bar(<!UNRESOLVED_REFERENCE!>::foo<!>)
+        }
+    }
+}
+
+inline fun <T, R> myWith(receiver: T, block: T.() -> R): R = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/chooseMostSpecificCandidateUsingCandidateDescriptorNotReflectionType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/chooseMostSpecificCandidateUsingCandidateDescriptorNotReflectionType.fir.kt
new file mode 100644
index 00000000000..0af36281c6b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/chooseMostSpecificCandidateUsingCandidateDescriptorNotReflectionType.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test() {
+    foo(String::extensionReceiver)
+    foo(::valueParameter)
+}
+
+fun CharSequence.extensionReceiver(): CharSequence = TODO()
+fun String.extensionReceiver(): String = TODO()
+
+fun valueParameter(c: CharSequence): CharSequence = TODO()
+fun valueParameter(s: String): CharSequence = TODO()
+
+fun <R> foo(f: (String) -> R) {}
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/chooseOuterCallBySingleCallableReference.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/chooseOuterCallBySingleCallableReference.fir.kt
new file mode 100644
index 00000000000..c0c15118202
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/chooseOuterCallBySingleCallableReference.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty1
+
+class Inv<T>
+
+fun <T, R : Number> foo(prop: KProperty1<T, R>, p: String = "") {}
+
+fun <T, R> foo(prop: KProperty1<T, Inv<R>>, p: Int = 42) {}
+
+class A {
+    val prop = 42
+}
+
+fun test() {
+    foo(A::prop)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/commonSupertypeFromReturnTypesOfCallableReference.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/commonSupertypeFromReturnTypesOfCallableReference.fir.kt
new file mode 100644
index 00000000000..2f5cc8259c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/commonSupertypeFromReturnTypesOfCallableReference.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+interface Parent
+interface Child1 : Parent
+interface Child2 : Parent
+
+fun foo(): Child1 = TODO()
+fun bar(): Child2 = TODO()
+
+fun <K> select(x: K, y: K): K = TODO()
+
+fun test() {
+    val a = select(::foo, ::bar)
+    a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/constructor.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/constructor.fir.kt
new file mode 100644
index 00000000000..6cde9ce2b55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/constructor.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Klass {
+    constructor(a: Int) {}
+    constructor(a: String) {}
+}
+
+fun user(f: (Int) -> Klass) {}
+
+fun fn() {
+    user(::Klass)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/eagerAndPostponedCallableReferences.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/eagerAndPostponedCallableReferences.fir.kt
new file mode 100644
index 00000000000..56770d43dd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/eagerAndPostponedCallableReferences.fir.kt
@@ -0,0 +1,35 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -UNUSED_EXPRESSION
+
+interface A
+interface B
+
+fun multiple(a: A) {}
+fun multiple(b: B) {}
+
+fun singleA(a: A) {}
+fun singleB(a: B) {}
+
+fun <T> foo(f: (T) -> Unit, g: (T) -> Unit): T = TODO()
+
+fun test() {
+    val a1 = foo(::singleA, ::multiple)
+    a1
+
+    val a2 = foo(::singleB, ::multiple)
+    a2
+
+    val a3 = foo(::multiple, ::singleA)
+    a3
+
+    val a4 = foo(::multiple, ::singleB)
+    a4
+
+    val a5 = foo(::singleA, ::singleA)
+    a5
+
+    val a6 = foo(::singleA, ::singleB)
+    a6
+
+    foo(<!UNRESOLVED_REFERENCE!>::multiple<!>, <!UNRESOLVED_REFERENCE!>::multiple<!>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/eagerResolveOfSingleCallableReference.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/eagerResolveOfSingleCallableReference.fir.kt
new file mode 100644
index 00000000000..653866f6135
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/eagerResolveOfSingleCallableReference.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class A
+class B : A()
+
+class Or(left: A, right: A) : A()
+
+class Out<out T>
+
+fun test(ls: Out<B>) {
+    ls.reduce(::Or)
+}
+
+fun <S, T : S> Out<T>.reduce(operation: (S, T) -> S): S = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/innerClassConstructorOnOuterClassInstance.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/innerClassConstructorOnOuterClassInstance.fir.kt
new file mode 100644
index 00000000000..abf0ac624ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/innerClassConstructorOnOuterClassInstance.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+abstract class A {
+    inner class InnerInA
+}
+
+abstract class B : A()
+
+fun foo(a: A) {
+    if (a is B) {
+        val v = a::InnerInA
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/intersectionTypeOverloadWithWrongParameter.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/intersectionTypeOverloadWithWrongParameter.fir.kt
new file mode 100644
index 00000000000..92fbfedf7be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/intersectionTypeOverloadWithWrongParameter.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KCallable
+
+class Foo {
+    fun <T> installRoute(handler: T) where T : (String) -> Any?, T : KCallable<*> {
+    }
+
+    fun <T> installRoute(handler: T) where T : () -> Any?, T : KCallable<*> {
+    }
+
+    fun foo() {
+        <!INAPPLICABLE_CANDIDATE!>installRoute<!><Any>(::route)
+    }
+
+}
+
+fun route(s: String): Any? = null
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/kt10036.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/kt10036.fir.kt
new file mode 100644
index 00000000000..da79d5657c9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/kt10036.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+// KT-10036 Ambiguous overload cannot be resolved when using a member function reference in Beta 2, that worked in Beta 1
+
+class OverloadTest {
+    fun foo(bar: Boolean) {}
+    fun foo(bar: Any?) {}
+}
+
+object Literal
+
+inline fun <T : Any> OverloadTest.overload(value: T?, function: OverloadTest.(T) -> Unit) {
+    if (value == null) foo(Literal) else <!INAPPLICABLE_CANDIDATE!>function<!>(value)
+}
+
+// Overload resolution ambiguity
+fun OverloadTest.overloadBoolean(value: Boolean?) = overload(value, OverloadTest::foo)
+
+// Works fine
+fun OverloadTest.overloadBoolean2(value: Boolean?) = overload(value) { foo(it) }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/kt10036_bound.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/kt10036_bound.fir.kt
new file mode 100644
index 00000000000..128893c5704
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/kt10036_bound.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class OverloadTest {
+    fun foo(bar: Boolean) {}
+    fun foo(bar: Any?) {}
+}
+
+inline fun <T : Any> OverloadTest.overload(value: T?, function: (T) -> Unit) {
+}
+
+fun OverloadTest.overloadBoolean(value: Boolean?) = overload(value, OverloadTest()::foo)
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/kt12338.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/kt12338.fir.kt
new file mode 100644
index 00000000000..4f5d6bf441a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/kt12338.fir.kt
@@ -0,0 +1,9 @@
+// KT-12338 Compiler error ERROR: Rewrite at slice LEXICAL_SCOPE key: REFERENCE_EXPRESSION with when and function references
+
+fun a() { }
+
+fun test() {
+    when {
+        true -> ::a
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/kt12751.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/kt12751.fir.kt
new file mode 100644
index 00000000000..47b939fef44
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/kt12751.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// KT-12751 Type inference failed with forEach and bound reference
+
+class L<out T>
+
+fun <T> L<T>.foo(action: (T) -> Unit): Unit {}
+
+class B {
+    fun remove(charSequence: CharSequence) {}
+}
+
+fun foo(list: L<CharSequence>, b: B) {
+    list.foo(b::remove)
+    list.foo<CharSequence>(b::remove)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/kt8596.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/kt8596.fir.kt
new file mode 100644
index 00000000000..fed7c090b75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/kt8596.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// KT-8596 Rewrite at slice LEXICAL_SCOPE for nested class constructor reference in an argument position
+
+class K {
+    class Nested
+}
+
+fun foo(f: Any) {}
+
+fun test1() {
+    foo(K::Nested)
+}
+
+// KT-10567 Error: Rewrite at slice LEXICAL_SCOPE key: REFERENCE_EXPRESSION
+
+class Foo(val a: String, val b: String)
+
+fun test2() {
+    val prop : Foo.() -> String = if (true) {
+        <!UNRESOLVED_REFERENCE!>Foo::a<!>
+    } else {
+        <!UNRESOLVED_REFERENCE!>Foo::b<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/kt9601.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/kt9601.fir.kt
new file mode 100644
index 00000000000..377c0bad1e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/kt9601.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+open class A
+class B: A()
+
+fun A.foo() {}
+fun B.foo() {} // more specific
+
+fun bar(a: Any) {}
+fun bar(a: Int) {}  // more specific
+
+fun test() {
+    <!UNRESOLVED_REFERENCE!>B::foo<!>
+    ::bar
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/moreSpecificAmbiguousExtensions.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/moreSpecificAmbiguousExtensions.fir.kt
new file mode 100644
index 00000000000..37ad6523f03
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/moreSpecificAmbiguousExtensions.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+interface IA
+interface IB : IA
+
+fun IA.extFun(x: IB) {}
+fun IB.extFun(x: IA) {}
+
+fun test() {
+    val extFun1 = IA::extFun
+    val extFun2 = IB::extFun
+}
+
+fun testWithExpectedType() {
+    val extFun_AB_A: IA.(IB) -> Unit = IA::extFun
+    val extFun_AA_B: IA.(IA) -> Unit = IB::extFun
+    val extFun_BB_A: IB.(IB) -> Unit = IA::extFun
+    val extFun_BA_B: IB.(IA) -> Unit = IB::extFun
+    val extFun_BB_B: IB.(IB) -> Unit = IB::extFun
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/moreSpecificSimple.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/moreSpecificSimple.fir.kt
new file mode 100644
index 00000000000..432f4e57d12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/moreSpecificSimple.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+interface IA
+interface IB : IA
+
+fun IA.extFun() {}
+fun IB.extFun() {}
+
+fun test() {
+    val extFun = <!UNRESOLVED_REFERENCE!>IB::extFun<!>
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><IB.() -> Unit>(extFun)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/multipleOutersAndMultipleCallableReferences.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/multipleOutersAndMultipleCallableReferences.fir.kt
new file mode 100644
index 00000000000..4ee3798be78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/multipleOutersAndMultipleCallableReferences.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Base
+class Inv<K> : Base
+
+fun foo(x: Int): Inv<Int> = TODO()
+fun foo(y: String): Inv<String> = TODO()
+
+fun <T, R : Number> bar(f: (T) -> Inv<R>, p: String = "") {}
+
+fun <T, R : Base> bar(f: (T) -> Inv<R>, p: Int = 4) {}
+
+fun test() {
+    bar(::foo)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/noAmbiguityBetweenTopLevelAndMemberProperty.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/noAmbiguityBetweenTopLevelAndMemberProperty.fir.kt
new file mode 100644
index 00000000000..8a1a1d391b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/noAmbiguityBetweenTopLevelAndMemberProperty.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty0
+import kotlin.reflect.KProperty1
+
+fun <R> property(property: KProperty0<R>): Int = 1
+fun <T, R> property(property: KProperty1<T, R>): String = ""
+
+val subject = ""
+
+class O {
+    val subject = ""
+}
+
+val someProperty0 = property(::subject)
+val someProperty1 = property(O::subject)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/noFakeDescriptorForObject.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/noFakeDescriptorForObject.fir.kt
new file mode 100644
index 00000000000..b925d9861e5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/noFakeDescriptorForObject.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+// KT-12322 Overload resolution ambiguity with constructor references when class has a companion object
+
+class Foo {
+    companion object
+}
+
+fun test() {
+    val a = ::Foo
+    checkSubtype<() -> Foo>(a)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/overloads.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/overloads.fir.kt
new file mode 100644
index 00000000000..4d70f87fc21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/overloads.fir.kt
@@ -0,0 +1,30 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+import kotlin.reflect.KFunction1
+
+open class A {
+    open fun bar() {}
+
+    fun bas() {}
+}
+class B: A() {
+    override fun bar() {}
+
+    fun bas(i: Int) {}
+}
+
+fun A.foo() {}
+fun B.foo() {}
+
+fun fas() {}
+fun fas(i: Int = 1) {}
+
+fun test() {
+    <!UNRESOLVED_REFERENCE!>B::foo<!> // todo KT-9601 Chose maximally specific function in callable reference
+
+    B::bar checkType { <!UNRESOLVED_REFERENCE!>_<!><KFunction1<B, Unit>>() }
+
+    <!UNRESOLVED_REFERENCE!>B::bas<!>
+
+    <!UNRESOLVED_REFERENCE!>::fas<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/overloadsBound.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/overloadsBound.fir.kt
new file mode 100644
index 00000000000..f2c83059d3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/overloadsBound.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// KT-12799 Bound callable references not resolved for overload
+
+class C {
+    fun xf1(){}
+    fun xf1(s: String){}
+}
+
+fun foo(p: (String) -> Unit){}
+
+fun bar(c: C) {
+    foo(c::xf1)
+}
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/overloadsMember.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/overloadsMember.fir.kt
new file mode 100644
index 00000000000..3bb136804eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/overloadsMember.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+// KT-9601 Chose maximally specific function in callable reference
+
+open class A {
+    fun foo(a: Any) {}
+    fun fas(a: Int) {}
+}
+class B: A() {
+    fun foo(a: Int) {}
+    fun fas(a: Any) {}
+}
+
+fun test() {
+    B::foo
+    B::fas
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/postponedResolveOfManyCallableReference.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/postponedResolveOfManyCallableReference.fir.kt
new file mode 100644
index 00000000000..d63b58549f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/postponedResolveOfManyCallableReference.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+interface A
+interface B
+
+fun foo(i: A) {}
+fun foo(b: B) {}
+
+fun <T> bar1(f: (T) -> Unit): T = TODO()
+fun <T> bar2(f: (T) -> Unit, e: T) {}
+
+fun test(a: A, b: B) {
+    val expectedType1: A = bar1(::foo)
+    val expectedType2: B = bar1(::foo)
+
+    bar2(::foo, a)
+    bar2(::foo, b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/resolveCallableReferencesAfterAllSimpleArguments.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/resolveCallableReferencesAfterAllSimpleArguments.fir.kt
new file mode 100644
index 00000000000..563f1fdc365
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/resolveCallableReferencesAfterAllSimpleArguments.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A
+interface B
+
+fun fooB(b: B) {}
+
+fun <T> bar(f: (T) -> Unit, e: T) {}
+fun <T> baz(e: T, f: (T) -> Unit) {}
+
+fun test(a: A, b: B) {
+    // Note that diagnostic is always on callable references as they are resolved after simple arguments
+    <!INAPPLICABLE_CANDIDATE!>baz<!>(a, ::fooB)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(::fooB, a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/resolveEqualsOperatorWithAnyExpectedType.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/resolveEqualsOperatorWithAnyExpectedType.fir.kt
new file mode 100644
index 00000000000..5a9c7237ffb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/resolveEqualsOperatorWithAnyExpectedType.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +NewInference
+
+interface Base
+
+fun <K> materialize(): K = TODO()
+
+fun <T : Base> Base.transform(): T = materialize()
+
+fun test(child: Base) {
+    child == child.transform()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/valVsFun.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/valVsFun.fir.kt
new file mode 100644
index 00000000000..44b0d4c9074
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/valVsFun.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.*
+
+class A {
+    val x = 1
+    fun x() {}
+}
+
+fun f1(): KProperty<Int> = A::x  // ok, property
+fun f2(): (A) -> Unit = A::x     // ok, function
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/withAs.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/withAs.fir.kt
new file mode 100644
index 00000000000..649671b5eb9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/withAs.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo() {}
+fun foo(s: String) {}
+
+fun bar(f: () -> Unit) = 1
+fun bar(f: (String) -> Unit) = 2
+
+val x1 = <!UNRESOLVED_REFERENCE!>::foo<!> as () -> Unit
+val x2 = bar(::foo as (String) -> Unit)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/withExtFun.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/withExtFun.fir.kt
new file mode 100644
index 00000000000..0b8f7d52ee7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/withExtFun.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -EXTENSION_SHADOWED_BY_MEMBER
+
+import kotlin.reflect.*
+
+fun <T> ofType(x: T): T = x
+
+class A {
+    val foo: Int = 0
+    fun foo() {}
+
+    fun bar() {}
+    val bar: Int = 0
+}
+
+fun A.foo(): String = "A"
+
+val x0 = A::foo
+
+val x1 = ofType<(A) -> Unit>(A::foo)
+val x2 = ofType<KProperty1<A, Int>>(A::foo)
+val x3: KProperty1<A, Int> = A::foo
+val x4: (A) -> String = A::foo
+
+val y0 = A::bar
+val y1 = ofType<(A) -> Unit>(A::bar)
+val y2 = ofType<KProperty1<A, Int>>(A::bar)
+val y3: KProperty1<A, Int> = A::bar
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/withGenericFun.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/withGenericFun.fir.kt
new file mode 100644
index 00000000000..97276eddf24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/withGenericFun.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// NI_EXPECTED_FILE
+
+fun <T, R> apply(x: T, f: (T) -> R): R = f(x)
+
+fun foo(i: Int) {}
+fun foo(s: String) {}
+
+val x1 = apply(1, ::foo)
+val x2 = apply("hello", ::foo)
+val x3 = <!INAPPLICABLE_CANDIDATE!>apply<!>(true, <!UNRESOLVED_REFERENCE!>::foo<!>)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/withPlaceholderTypes.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/withPlaceholderTypes.fir.kt
new file mode 100644
index 00000000000..529469c7d36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/withPlaceholderTypes.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-CONFLICTING_JVM_DECLARATIONS
+// NI_EXPECTED_FILE
+
+fun foo(i: Int) = "$i"
+fun foo(s: String) = s
+
+fun bar(s: String) = s
+
+fun qux(i: Int, j: Int, k: Int): Int = i + j + k
+fun qux(a: String, b: String, c: String, d: String) {}
+
+fun fn1(x: Int, f1: (Int) -> String, f2: (String) -> String) = f2(f1(x))
+
+fun fn2(f1: (Int) -> String,    f2: (String) -> String  ) = f2(f1(0))
+fun fn2(f1: (Int) -> Int,       f2: (Int) -> String     ) = f2(f1(0))
+fun fn2(f1: (String) -> String, f2: (String) -> String  ) = f2(f1(""))
+
+fun fn3(i: Int, f: (Int, Int, Int) -> Int): Int = f(i, i, i)
+
+val x1 = fn1(1, ::foo, ::foo)
+val x2 = fn1(1, ::foo, ::bar)
+
+val x3 = fn2(::bar, ::foo)
+val x4 = <!AMBIGUITY!>fn2<!>(<!UNRESOLVED_REFERENCE!>::foo<!>, ::bar)
+val x5 = <!AMBIGUITY!>fn2<!>(<!UNRESOLVED_REFERENCE!>::foo<!>, <!UNRESOLVED_REFERENCE!>::foo<!>)
+
+val x6 = fn3(1, ::qux)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/resolve/withVararg.fir.kt b/compiler/testData/diagnostics/tests/callableReference/resolve/withVararg.fir.kt
new file mode 100644
index 00000000000..364e0e57ca7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/resolve/withVararg.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(vararg ii: Int) {}
+fun foo(vararg ss: String) {}
+fun foo(i: Int) {}
+
+val fn1: (Int) -> Unit = ::foo
+val fn2: (IntArray) -> Unit = ::foo
+val fn3: (Int, Int) -> Unit = <!UNRESOLVED_REFERENCE!>::foo<!>
+val fn4: (Array<String>) -> Unit = ::foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/rewriteAtSliceOnGetOperator.fir.kt b/compiler/testData/diagnostics/tests/callableReference/rewriteAtSliceOnGetOperator.fir.kt
new file mode 100644
index 00000000000..8fe7a6dc817
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/rewriteAtSliceOnGetOperator.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty1
+
+class Sample(val str: String)
+
+class Inv<T>
+
+class Form {
+    operator fun <F> get(field: KProperty1<*, F>): Inv<F> = TODO()
+}
+
+fun <K> foo(i: Inv<K>) {}
+
+fun test(f: Form) {
+    foo(f[Sample::str])
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/sam.fir.kt b/compiler/testData/diagnostics/tests/callableReference/sam.fir.kt
new file mode 100644
index 00000000000..e733d9060f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/sam.fir.kt
@@ -0,0 +1,31 @@
+// FILE: test/GenericSam.java
+
+package test;
+
+public interface GenericSam<T> {
+    void invoke(T t);
+}
+
+// FILE: test.kt
+
+import test.GenericSam
+
+fun f1() = Runnable::class
+fun f2() = Runnable::run
+fun f3() = java.lang.Runnable::class
+fun f4() = java.lang.Runnable::run
+
+fun f5() = GenericSam::class
+fun f6() = GenericSam<*>::invoke
+fun f7() = test.GenericSam::class
+fun f8() = test.GenericSam<String>::invoke
+
+fun g1() = Runnable {}::class
+fun g2() = Runnable {}::run
+fun g3() = java.lang.Runnable {}::class
+fun g4() = java.lang.Runnable {}::run
+
+fun g5() = GenericSam<String> {}::class
+fun g6() = GenericSam<String> {}::invoke
+fun g7() = test.GenericSam<String> {}::class
+fun g8() = test.GenericSam<String> {}::invoke
diff --git a/compiler/testData/diagnostics/tests/callableReference/subtypeArgumentFromRHSForReference.fir.kt b/compiler/testData/diagnostics/tests/callableReference/subtypeArgumentFromRHSForReference.fir.kt
new file mode 100644
index 00000000000..e6d7d426df4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/subtypeArgumentFromRHSForReference.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.*
+
+interface Parent
+class Child : Parent
+
+class ChildHolder(var child: Child)
+
+interface Inv<T>
+
+class Form {
+    fun <F> get0(field: KMutableProperty<F>): Inv<F> = TODO()
+    fun <F> get1(field: KProperty<F>): Inv<F> = TODO()
+    fun <F> get2(field: KCallable<F>): Inv<F> = TODO()
+    fun <F> get3(field: KMutableProperty1<*, F>): Inv<F> = TODO()
+}
+
+fun <T : Parent> radio(field: Inv<T>) {}
+
+fun test(form: Form) {
+    radio(form.get0(ChildHolder::child))
+    radio(form.get1(ChildHolder::child))
+    radio(form.get2(ChildHolder::child))
+    radio(form.get3(ChildHolder::child))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/suspendCallableReference.fir.kt b/compiler/testData/diagnostics/tests/callableReference/suspendCallableReference.fir.kt
new file mode 100644
index 00000000000..fdde41c88ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/suspendCallableReference.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// ISSUE: KT-32452
+
+interface A {
+    suspend fun foo(input: String): String
+}
+
+open class B<T : Any> {
+    fun <U, R : Any, T> call(function: suspend T.(U) -> R): R = TODO()
+
+    fun <U, R : Any, T> call(function: suspend T.(U) -> List<R>): List<R> = TODO()
+}
+
+class MyService : A, B<A>() {
+    override suspend fun foo(input: String) = call(A::foo)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/typealiases.fir.kt b/compiler/testData/diagnostics/tests/callableReference/typealiases.fir.kt
new file mode 100644
index 00000000000..3fed265a53f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/typealiases.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+// Issue: KT-31199
+
+typealias Global = String
+
+fun String.toUpperCase(): String = TODO()
+
+inline fun <T, R> Iterable<T>.myMap(transform: (T) -> R): List<R> {
+    TODO()
+}
+
+fun usesGlobal(p: List<Global>) {
+    p.<!INAPPLICABLE_CANDIDATE!>myMap<!>(Global::toUpperCase)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/unused.fir.kt b/compiler/testData/diagnostics/tests/callableReference/unused.fir.kt
new file mode 100644
index 00000000000..b6327ef551f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/unused.fir.kt
@@ -0,0 +1,23 @@
+fun foo() {
+
+}
+
+class A {
+    fun foo() {
+
+    }
+
+    class B
+}
+
+fun A.bar() {
+
+}
+
+fun test() {
+    ::foo
+    ::A
+    A::B
+    A::foo
+    A::bar
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/callableReference/whitespacesInExpression.fir.kt b/compiler/testData/diagnostics/tests/callableReference/whitespacesInExpression.fir.kt
new file mode 100644
index 00000000000..a2505399877
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/callableReference/whitespacesInExpression.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+class Foo
+
+fun Foo?.bar() {}
+
+fun test() {
+    val r1 = Foo ?:: bar
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><(Foo?) -> Unit>(r1)
+
+    val r2 = Foo ? :: bar
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><(Foo?) -> Unit>(r2)
+
+    val r3 = Foo ? ? :: bar
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><(Foo?) -> Unit>(r3)
+}
diff --git a/compiler/testData/diagnostics/tests/cast/AsArray.fir.kt b/compiler/testData/diagnostics/tests/cast/AsArray.fir.kt
new file mode 100644
index 00000000000..4905c48dc29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsArray.fir.kt
@@ -0,0 +1 @@
+fun f(x: Any) = x as Array<String>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/AsErasedError.fir.kt b/compiler/testData/diagnostics/tests/cast/AsErasedError.fir.kt
new file mode 100644
index 00000000000..b587d66e767
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsErasedError.fir.kt
@@ -0,0 +1,2 @@
+
+fun ff(c: MutableCollection<String>) = c as MutableList<Int>
diff --git a/compiler/testData/diagnostics/tests/cast/AsErasedFine.fir.kt b/compiler/testData/diagnostics/tests/cast/AsErasedFine.fir.kt
new file mode 100644
index 00000000000..ef761f25328
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsErasedFine.fir.kt
@@ -0,0 +1,2 @@
+
+fun ff(c: MutableCollection<String>) = c as MutableList<String>
diff --git a/compiler/testData/diagnostics/tests/cast/AsErasedStar.fir.kt b/compiler/testData/diagnostics/tests/cast/AsErasedStar.fir.kt
new file mode 100644
index 00000000000..2ec2a30cb89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsErasedStar.fir.kt
@@ -0,0 +1,3 @@
+
+fun ff(l: Any) = l as MutableList<*>
+
diff --git a/compiler/testData/diagnostics/tests/cast/AsErasedWarning.fir.kt b/compiler/testData/diagnostics/tests/cast/AsErasedWarning.fir.kt
new file mode 100644
index 00000000000..09fadc462c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsErasedWarning.fir.kt
@@ -0,0 +1,2 @@
+
+fun ff(a: Any) = a as MutableList<String>
diff --git a/compiler/testData/diagnostics/tests/cast/AsInBinaryUnary.fir.kt b/compiler/testData/diagnostics/tests/cast/AsInBinaryUnary.fir.kt
new file mode 100644
index 00000000000..87afc9c3581
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsInBinaryUnary.fir.kt
@@ -0,0 +1,31 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Base
+
+class Impl1 : Base
+
+class Impl2 : Base
+
+operator fun Base.plus(arg: Base) = Impl1()
+
+operator fun Impl2.plus(arg: Base) = Impl2()
+
+operator fun Base.plus(arg: Impl2) = Impl2()
+
+operator fun Base.unaryMinus() = Impl1()
+
+operator fun Impl2.unaryMinus() = Impl2()
+
+// See also KT-10384: in non-error functions, as is necessary!
+fun add1(x: Impl2, y: Base): Impl1 = x as Base + y
+
+fun error1(x: Impl2, y: Base): Impl1 = x + y
+
+fun add2(x: Base, y: Impl2): Impl1 = x + y as Base
+
+fun error2(x: Base, y: Impl2): Impl1 = x + y
+
+fun minus3(x: Impl2): Impl1 = -(x as Base)
+
+fun error3(x: Impl2): Impl1 = -x
diff --git a/compiler/testData/diagnostics/tests/cast/AsInBlockWithReturnType.fir.kt b/compiler/testData/diagnostics/tests/cast/AsInBlockWithReturnType.fir.kt
new file mode 100644
index 00000000000..e29d857d649
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsInBlockWithReturnType.fir.kt
@@ -0,0 +1,53 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun runWithoutReturn(r: () -> Unit) = r()
+
+fun testRun() {
+    run {
+        1 as Any
+        1 as Any
+    }
+
+    run<Any> {
+        1 as Any
+        1 as Any
+    }
+
+    fun foo(): Int = 1
+
+    run {
+        foo() as Any
+    }
+
+    run {
+        (if (true) 1 else 2) as Any
+    }
+
+    run<Int?> {
+        1 as Int
+        1 as Int
+    }
+
+    runWithoutReturn {
+        1 as Any
+        1 as Any
+    }
+}
+
+fun testReturn(): Number {
+    run { 1 as Number }
+    return run { 1 as Number }
+}
+
+fun <T> testDependent() {
+    listOf(1).map {
+        it as Any
+        it as Any
+    }
+
+    listOf<T>().map { it as Any? }
+}
+
+fun <T> listOf(vararg elements: T): List<T> = TODO()
+fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/AsInExpressionBody.fir.kt b/compiler/testData/diagnostics/tests/cast/AsInExpressionBody.fir.kt
new file mode 100644
index 00000000000..fc2124f4cb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsInExpressionBody.fir.kt
@@ -0,0 +1,12 @@
+fun <T> id(x: T): T = x
+
+fun foo() = 1 as Any
+fun bar() = id(1) as Any
+fun baz() = (1 + 1) as Any
+
+val functionLiteral1 = fun() = 1 as Any
+val functionLiteral2 = fun() = id(1) as Any
+val functionLiteral3 = fun() = (1 + 1) as Any
+
+// TODO: this and more complex cases are not supported yet
+fun baz(b: Boolean) = if (b) 1 as Any else 42 as Any?
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.fir.kt b/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.fir.kt
new file mode 100644
index 00000000000..27cdb37c820
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun test() {
+    val a = 1 as Any?
+    val b: Number = 1 as Number
+    val c = null as String?
+    val d: Number = 1 as Int
+}
+
+val c1 get() = 1 as Number
+val c2: Number get() = 1 as Number
+
+val d: Number
+    get() {
+        1 as Number
+        return 1 as Number
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/AsNothing.fir.kt b/compiler/testData/diagnostics/tests/cast/AsNothing.fir.kt
new file mode 100644
index 00000000000..230f58ce8de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsNothing.fir.kt
@@ -0,0 +1,14 @@
+// Nothing can be cast to Nothing
+fun foo(x: String) {
+    x as Nothing
+}
+
+fun gav(y: String?) {
+    y as Nothing
+}
+
+// Only nullable can be cast to Nothing?
+fun bar(x: String, y: String?) {
+    x as Nothing?
+    y as Nothing?
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/AsTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/cast/AsTypeAlias.fir.kt
new file mode 100644
index 00000000000..279219ba2ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsTypeAlias.fir.kt
@@ -0,0 +1,18 @@
+typealias MyString = String
+
+val x: MyString = ""
+val y = x as Any
+
+interface Base
+class Derived : Base
+interface Other : Base
+typealias IBase = Base
+typealias IOther = Other
+
+val ib: IBase = Derived()
+val d = ib as Derived
+val o = ib as Other
+val io = ib as IOther
+val s = d as String
+val ms = d as MyString
+
diff --git a/compiler/testData/diagnostics/tests/cast/AsWithOtherParameter.fir.kt b/compiler/testData/diagnostics/tests/cast/AsWithOtherParameter.fir.kt
new file mode 100644
index 00000000000..2b412a0f643
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsWithOtherParameter.fir.kt
@@ -0,0 +1,34 @@
+// See also: KT-6611 (cast can never succeed: Class<T> -> Class<Any>)
+
+class Class<T>(val name: String, val instance: T)
+
+fun <T> test(clazz: Class<T>) {
+    println((clazz as Class<Any>).name)
+}
+
+fun use() {
+    test(Class("String", ""))
+}
+
+fun checkArrays(): Array<Any> {
+    val someArray = arrayOfNulls<Any>(5)
+    someArray as Array<Int>
+    return someArray as Array<Any>
+}
+
+class Wrapper<T>(val x: T)
+
+fun checkArrays2(): Array<Wrapper<String>> {
+    val someArray = arrayOf(Wrapper(1), Wrapper(2))
+    return someArray as Array<Wrapper<String>>
+}
+
+fun checkArrays3() {
+    val someArray = arrayOfNulls<String>(1)
+    someArray as Array<Any>
+    val intArray = arrayOfNulls<Int>(1)
+    intArray as Array<Any>
+}
+
+fun println(s: String) = s
+
diff --git a/compiler/testData/diagnostics/tests/cast/DowncastMap.fir.kt b/compiler/testData/diagnostics/tests/cast/DowncastMap.fir.kt
new file mode 100644
index 00000000000..e7b33828ab6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/DowncastMap.fir.kt
@@ -0,0 +1,10 @@
+interface Map<K, out V>
+interface MutableMap<K, V>: Map<K, V> {
+  operator fun set(k: K, v: V)
+}
+
+fun p(p: Map<String, Int>) {
+    if (p is MutableMap<String, Int>) {
+        p[""] = 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/ExtensionAsNonExtension.fir.kt b/compiler/testData/diagnostics/tests/cast/ExtensionAsNonExtension.fir.kt
new file mode 100644
index 00000000000..b7dde7e3775
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/ExtensionAsNonExtension.fir.kt
@@ -0,0 +1,10 @@
+fun f(a: (Int) -> Unit) {
+    a as Int.() -> Unit
+
+    f1(a as Int.() -> Unit)
+}
+
+fun f1(a: Int.() -> Unit) {
+    a as (Int) -> Unit
+    f(a as (Int) -> Unit)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/FlexibleTargetType.fir.kt b/compiler/testData/diagnostics/tests/cast/FlexibleTargetType.fir.kt
new file mode 100644
index 00000000000..8041cb1ef69
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/FlexibleTargetType.fir.kt
@@ -0,0 +1,26 @@
+// FILE: Foo.java
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class Foo {
+    static Foo create() { return null; }
+
+    @Nullable
+    static Foo createN() { return null; }
+
+    @NotNull
+    static Foo createNN() { return null; }
+}
+
+// FILE: sample.kt
+
+fun test() {
+    Foo.create() as Foo
+    Foo.createN() as Foo
+    Foo.createNN() as Foo
+
+    Foo.create() as Foo?
+    Foo.createN() as Foo?
+    Foo.createNN() as Foo?
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForDerivedWithOneSubstitutedAndOneSameGeneric.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForDerivedWithOneSubstitutedAndOneSameGeneric.fir.kt
new file mode 100644
index 00000000000..5df28bb45fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForDerivedWithOneSubstitutedAndOneSameGeneric.fir.kt
@@ -0,0 +1,5 @@
+open class BaseTwo<A, B>
+open class DerivedWithOne<D>: BaseTwo<D, String>()
+
+// a is BaseTwo<T, U> => if (a is DerivedWithOne<?>) a is DerivedWithOne<T>
+fun <T, U> testing(a: BaseTwo<T, U>) = a is DerivedWithOne<T>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForExactSupertypeCheck.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForExactSupertypeCheck.fir.kt
new file mode 100644
index 00000000000..51c6eab4642
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForExactSupertypeCheck.fir.kt
@@ -0,0 +1,5 @@
+open class Base<A>
+class Some: Base<Int>()
+
+// a is Some => a is Base<Int>
+fun f(a: Some) = a is Base<Int>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForOverridenVarianceWithProjection.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForOverridenVarianceWithProjection.fir.kt
new file mode 100644
index 00000000000..09d7b2f6792
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForOverridenVarianceWithProjection.fir.kt
@@ -0,0 +1,8 @@
+open class A
+open class B: A()
+
+open class Base<out T>
+open class SubBase<T> : Base<T>()
+
+// l is Base<+B> => if (l is SubBase<?>) l is SubBase<+B> => l is SubBase<+A>
+fun ff(l: Base<B>) = l is SubBase<out A>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForSupertypeCheckWithContrvariance.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForSupertypeCheckWithContrvariance.fir.kt
new file mode 100644
index 00000000000..db875931272
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForSupertypeCheckWithContrvariance.fir.kt
@@ -0,0 +1,8 @@
+open class A
+open class B: A()
+
+open class Base<in T>
+class SubBase: Base<A>()
+
+// f is SubBase => f is Base<A> => (Base<Contravariant T>, B <: A) f is Base<B>
+fun test(f: SubBase) = f is Base<B>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForSupertypeCheckWithCovariance.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForSupertypeCheckWithCovariance.fir.kt
new file mode 100644
index 00000000000..a7ca5876259
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForSupertypeCheckWithCovariance.fir.kt
@@ -0,0 +1,8 @@
+open class A
+open class B: A()
+
+open class Base<out T>
+class SubBase: Base<B>()
+
+// f is SubBase => (SubBase <: Base<B>) f is Base<B> => (B <: A, Base<Covariant T> => SubBase <: Base<A>) f is Base<A>
+fun test(f: SubBase) = f is Base<A>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithIrrelevantMixin.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithIrrelevantMixin.fir.kt
new file mode 100644
index 00000000000..f69dc7a1aaf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithIrrelevantMixin.fir.kt
@@ -0,0 +1,9 @@
+interface A
+interface B: A
+interface D
+
+interface BaseSuper<out T>
+interface BaseImpl: BaseSuper<D>
+interface DerivedSuper<out S>: BaseSuper<S>, BaseImpl
+
+fun test(t: BaseSuper<B>) = t is DerivedSuper<A>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithTwoSameTypeSubstitutions.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithTwoSameTypeSubstitutions.fir.kt
new file mode 100644
index 00000000000..41baa2a3676
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithTwoSameTypeSubstitutions.fir.kt
@@ -0,0 +1,6 @@
+open class BaseMulti<out A, B>
+class SomeMultiDerived<out D>: BaseMulti<D, Any>()
+
+// t is BaseMulti<+String, String> => if (t is SomeMultiDerived<?>) => t is SomeMultiDerived<+String> =>
+//     => (String <: Any, SomeMultiDerived<Covariant D>) t is SomeMultiDerived<+Any>
+fun someDerived(t: BaseMulti<String, String>) = t is SomeMultiDerived<Any>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithoutTypeArguments.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithoutTypeArguments.fir.kt
new file mode 100644
index 00000000000..a481246aaad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowForTypeWithoutTypeArguments.fir.kt
@@ -0,0 +1,5 @@
+open class Base<A>
+class Some: Base<Int>()
+
+// No erased types in check
+fun <A> f(a: Base<A>) = a is Some
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOut.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOut.fir.kt
new file mode 100644
index 00000000000..29ac268ad0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOut.fir.kt
@@ -0,0 +1 @@
+fun f(a: MutableList<out Number>) = a is MutableList<out Any>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOut2.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOut2.fir.kt
new file mode 100644
index 00000000000..6f7bc4f981a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOut2.fir.kt
@@ -0,0 +1 @@
+fun f(a: MutableList<String>) = a is MutableList<out CharSequence>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOutAtClass.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOutAtClass.fir.kt
new file mode 100644
index 00000000000..f1ba3800c08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowFromOutAtClass.fir.kt
@@ -0,0 +1 @@
+fun f(a: List<Number>) = a is List<Any>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowParameterSubtype.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowParameterSubtype.fir.kt
new file mode 100644
index 00000000000..995258b9f83
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowParameterSubtype.fir.kt
@@ -0,0 +1,7 @@
+
+open class A
+
+class B : A()
+
+fun ff(l: MutableCollection<B>) = l is MutableList<out A>
+
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowSameClassParameter.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowSameClassParameter.fir.kt
new file mode 100644
index 00000000000..d8986f1938f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowSameClassParameter.fir.kt
@@ -0,0 +1,3 @@
+
+fun ff(l: MutableCollection<String>) = l is MutableList<String>
+
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedAllowSameParameterParameter.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedAllowSameParameterParameter.fir.kt
new file mode 100644
index 00000000000..d835e23aed3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedAllowSameParameterParameter.fir.kt
@@ -0,0 +1,3 @@
+
+fun <T> ff(l: MutableCollection<T>) = l is MutableList<T>
+
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDisallowDifferentArgInvariantPosition.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowDifferentArgInvariantPosition.fir.kt
new file mode 100644
index 00000000000..0a56fe22872
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowDifferentArgInvariantPosition.fir.kt
@@ -0,0 +1 @@
+fun f(a: MutableList<String>) = a is MutableList<CharSequence>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDisallowForOverridenVariance.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowForOverridenVariance.fir.kt
new file mode 100644
index 00000000000..7960af40eff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowForOverridenVariance.fir.kt
@@ -0,0 +1,8 @@
+open class A
+open class B: A()
+
+open class Base<out T>
+open class SubBase<T> : Base<T>()
+
+
+fun ff(l: Base<B>) = l is SubBase<A>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDisallowForTypeWithConstraints.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowForTypeWithConstraints.fir.kt
new file mode 100644
index 00000000000..afba616ee44
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowForTypeWithConstraints.fir.kt
@@ -0,0 +1,6 @@
+interface A
+interface B: A
+
+interface Base<T>
+
+fun <T> test(a: Base<B>) where T: Base<A> = a is T
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromAny.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromAny.fir.kt
new file mode 100644
index 00000000000..5d98c89982a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromAny.fir.kt
@@ -0,0 +1,2 @@
+
+fun ff(l: Any) = l is MutableList<String>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromIn.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromIn.fir.kt
new file mode 100644
index 00000000000..f1894cfe1b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromIn.fir.kt
@@ -0,0 +1 @@
+fun f(a: MutableList<in String>) = a is MutableList<CharSequence>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromOut.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromOut.fir.kt
new file mode 100644
index 00000000000..0e3c75f4889
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromOut.fir.kt
@@ -0,0 +1,2 @@
+
+fun f(a : MutableList<out Any>) = a is MutableList<out Int>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromOutAtClass.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromOutAtClass.fir.kt
new file mode 100644
index 00000000000..47977766298
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDisallowFromOutAtClass.fir.kt
@@ -0,0 +1 @@
+fun f(a: List<Any>) = a is List<Number>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDissallowForSubtypeMappedToTwoParamsWithFirstInvalid.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDissallowForSubtypeMappedToTwoParamsWithFirstInvalid.fir.kt
new file mode 100644
index 00000000000..631525fddac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDissallowForSubtypeMappedToTwoParamsWithFirstInvalid.fir.kt
@@ -0,0 +1,8 @@
+open class A
+open class B: A()
+open class D
+
+open class Base<out T, out U>
+open class Derived<out S>: Base<S, S>()
+
+fun test(a: Base<D, B>) = a is Derived<A>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedDissallowForSubtypeMappedToTwoParamsWithSecondInvalid.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedDissallowForSubtypeMappedToTwoParamsWithSecondInvalid.fir.kt
new file mode 100644
index 00000000000..959156243a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedDissallowForSubtypeMappedToTwoParamsWithSecondInvalid.fir.kt
@@ -0,0 +1,8 @@
+open class A
+open class B: A()
+open class D
+
+open class Base<out T, out U>
+open class Derived<out S>: Base<S, S>()
+
+fun test(a: Base<B, D>) = a is Derived<A>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedNonGeneric.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedNonGeneric.fir.kt
new file mode 100644
index 00000000000..a27a5165198
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedNonGeneric.fir.kt
@@ -0,0 +1,3 @@
+interface A
+interface B
+fun testing(a: A) = a as B
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedNullableTasT.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedNullableTasT.fir.kt
new file mode 100644
index 00000000000..0a32f3a862f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedNullableTasT.fir.kt
@@ -0,0 +1 @@
+fun <T: Any> testing(a: T?) = a is T
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedStar.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedStar.fir.kt
new file mode 100644
index 00000000000..0143c3643ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedStar.fir.kt
@@ -0,0 +1,2 @@
+
+fun ff(l: Any) = l is MutableList<*>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedTasT.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedTasT.fir.kt
new file mode 100644
index 00000000000..ae1fa33c9f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedTasT.fir.kt
@@ -0,0 +1 @@
+fun <T> testing(a: T) = a is T
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedToErrorType.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedToErrorType.fir.kt
new file mode 100644
index 00000000000..21dd6efa00e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedToErrorType.fir.kt
@@ -0,0 +1 @@
+fun testing(a: Any) = a is UnresolvedType<Int>
diff --git a/compiler/testData/diagnostics/tests/cast/IsErasedUpcastToNonReified.fir.kt b/compiler/testData/diagnostics/tests/cast/IsErasedUpcastToNonReified.fir.kt
new file mode 100644
index 00000000000..84d2d5ea5f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsErasedUpcastToNonReified.fir.kt
@@ -0,0 +1,27 @@
+fun <T, S : T> test(x: T?, y: S, z: T) {
+    x is T
+    x is T?
+
+    y is T
+    y is S
+    y is T?
+    y is S?
+
+    z is T
+    z is T?
+
+    null as T
+    null as T?
+    null as S
+}
+
+inline fun <reified T> test(x: T?) {
+    x is T
+    null as T
+    null as T?
+}
+
+fun <T> foo(x: List<T>, y: List<T>?) {
+    x is List<T>
+    y is List<T>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsForTypeWithComplexUpperBound.fir.kt b/compiler/testData/diagnostics/tests/cast/IsForTypeWithComplexUpperBound.fir.kt
new file mode 100644
index 00000000000..604eb17f20d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsForTypeWithComplexUpperBound.fir.kt
@@ -0,0 +1,34 @@
+interface A<T>
+class B : A<String> {}
+
+fun <T, U : A<T>> test1(a: U) {
+    a is B
+}
+
+fun <T, S : A<T>, U : S> test2(a: U) {
+    a is B
+}
+
+fun <T : A<String>, V : A<Int>> test3(a: T, b: V) {
+    a is B
+    b is B
+}
+
+fun <T, V : A<out T>> test4(a: T, b: V) {
+    a is B
+    b is B
+}
+
+interface Out<out T>
+class OutNothing : Out<Nothing>
+
+fun <T, S : Out<T>> test5(a: S) {
+    a is OutNothing
+}
+
+interface In<in T>
+class InNothing : In<Nothing>
+
+fun <T, S : In<T>> test6(a: S) {
+    a is InNothing
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsRecursionSustainable.fir.kt b/compiler/testData/diagnostics/tests/cast/IsRecursionSustainable.fir.kt
new file mode 100644
index 00000000000..3efa41504ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsRecursionSustainable.fir.kt
@@ -0,0 +1,6 @@
+open class RecA<T>: RecB<T>()
+open class RecB<T>: <!OTHER_ERROR!>RecA<T><!>()
+open class SelfR<T>: <!OTHER_ERROR!>SelfR<T><!>()
+
+fun test(f: SelfR<String>) = f is RecA<String>
+fun test(f: RecB<String>) = f is RecA<String>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/IsTraits.fir.kt b/compiler/testData/diagnostics/tests/cast/IsTraits.fir.kt
new file mode 100644
index 00000000000..defcbfb3bc9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsTraits.fir.kt
@@ -0,0 +1,4 @@
+interface Aaa
+interface Bbb
+
+fun f(a: Aaa) = a is Bbb
diff --git a/compiler/testData/diagnostics/tests/cast/IsWithCycleUpperBounds.fir.kt b/compiler/testData/diagnostics/tests/cast/IsWithCycleUpperBounds.fir.kt
new file mode 100644
index 00000000000..598a3e7c21e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/IsWithCycleUpperBounds.fir.kt
@@ -0,0 +1,14 @@
+// check that there is no SOE on checking for instance
+interface Visitor<T>
+interface Acceptor<T>
+
+class Word : Acceptor<Visitor<Word>>
+
+class V : Visitor<Word>
+
+class S<T : Acceptor<U>, U : Visitor<T>>(val visitor: U, val acceptor: T) {
+    fun test() {
+        visitor is V
+        acceptor is Word
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/NullableToNullable.fir.kt b/compiler/testData/diagnostics/tests/cast/NullableToNullable.fir.kt
new file mode 100644
index 00000000000..cd76ae9a3c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/NullableToNullable.fir.kt
@@ -0,0 +1,7 @@
+// From KT-13324: always succeeds
+val x = null as String?
+// From KT-260: sometimes succeeds
+fun foo(a: String?): Int? {
+    val c = a as? Int?
+    return c
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/StableTypeForUselessCast.fir.kt b/compiler/testData/diagnostics/tests/cast/StableTypeForUselessCast.fir.kt
new file mode 100644
index 00000000000..fcd72edcbe1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/StableTypeForUselessCast.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface I1
+interface I2
+
+fun foo(i: I1) {}
+fun foo(i: I2) {}
+
+fun bar(i: I1) {
+    if (i is I2) {
+        foo(i as I1)
+        foo(i as I2)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/UselessSafeCast.fir.kt b/compiler/testData/diagnostics/tests/cast/UselessSafeCast.fir.kt
new file mode 100644
index 00000000000..f35df122d02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/UselessSafeCast.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+fun test(x: Int?) {
+    val a1 = x as? Int
+    val a2 = x as? Int?
+    val a3 = x as? Number
+    val a4 = x as? Number?
+    val a5: Int? = x as? Int
+    val a6: Number? = x as? Int
+    val a7: Number? = 1 as? Number
+
+    run { x as? Int }
+    run { x as? Number }
+
+    foo(x as? Number)
+
+    if (x is Int) {
+        val b = x as? Int
+    }
+}
+
+fun foo(x: Number?) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/WhenErasedDisallowFromAny.fir.kt b/compiler/testData/diagnostics/tests/cast/WhenErasedDisallowFromAny.fir.kt
new file mode 100644
index 00000000000..b073dff8735
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/WhenErasedDisallowFromAny.fir.kt
@@ -0,0 +1,5 @@
+
+fun ff(l: Any) = when(l) {
+    is MutableList<String> -> 1
+    else <!SYNTAX!>2<!>
+}
diff --git a/compiler/testData/diagnostics/tests/cast/WhenWithExpression.fir.kt b/compiler/testData/diagnostics/tests/cast/WhenWithExpression.fir.kt
new file mode 100644
index 00000000000..9a60e0bf91e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/WhenWithExpression.fir.kt
@@ -0,0 +1,11 @@
+class List<out T>(val size : Int) {
+    companion object {
+        val Nil = List<Nothing>(0)
+    }
+}
+
+fun List<String>.join() =
+        when (this) {
+            List.Nil -> "[]" // CANNOT_CHECK_FOR_ERASED was reported
+            else -> ""
+        }
diff --git a/compiler/testData/diagnostics/tests/cast/bare/AsNestedBare.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/AsNestedBare.fir.kt
new file mode 100644
index 00000000000..92b6a51fcb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/AsNestedBare.fir.kt
@@ -0,0 +1,10 @@
+interface Tr
+interface G<T>
+
+fun test(tr: Tr): Any {
+    return tr as G<G>
+}
+
+fun test1(tr: Tr): Any {
+    return tr as G.(G) -> G
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/AsNullable.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/AsNullable.fir.kt
new file mode 100644
index 00000000000..36520d5aab8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/AsNullable.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+interface Tr<T>
+interface G<T> : Tr<T>
+
+fun test(tr: Tr<String>) {
+    val v = tr as G?
+    // If v is not nullable, there will be a warning on this line:
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><G<String>>(v!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/AsNullableNotEnough.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/AsNullableNotEnough.fir.kt
new file mode 100644
index 00000000000..1b46e9c5cdc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/AsNullableNotEnough.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+interface Tr
+interface G<T>
+
+fun test(tr: Tr) {
+    val v = tr as G?
+    // If v is not nullable, there will be a warning on this line:
+    checkSubtype<G<*>>(v!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/EitherAs.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/EitherAs.fir.kt
new file mode 100644
index 00000000000..7dd8ca15808
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/EitherAs.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+interface Either<out A, out B>
+interface Left<out A>: Either<A, Nothing>
+interface Right<out B>: Either<Nothing, B>
+
+class C1(val v1: Int)
+class C2(val v2: Int)
+
+fun _as_left(e: Either<C1, C2>): Any {
+    val v = e as Left
+    return <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Left<C1>>(v)
+}
+
+fun _as_right(e: Either<C1, C2>): Any {
+    val v = e as Right
+    return <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Right<C2>>(v)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/EitherIs.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/EitherIs.fir.kt
new file mode 100644
index 00000000000..81c74588732
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/EitherIs.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+interface Either<out A, out B>
+interface Left<out A>: Either<A, Nothing> {
+    val value: A
+}
+interface Right<out B>: Either<Nothing, B> {
+    val value: B
+}
+
+class C1(val v1: Int)
+class C2(val v2: Int)
+
+fun _is_l(e: Either<C1, C2>): Any {
+    if (e is Left) {
+        return e.value.<!UNRESOLVED_REFERENCE!>v1<!>
+    }
+    return e
+}
+
+fun _is_r(e: Either<C1, C2>): Any {
+    if (e is Right) {
+        return e.value.<!UNRESOLVED_REFERENCE!>v2<!>
+    }
+    return e
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/EitherNotIs.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/EitherNotIs.fir.kt
new file mode 100644
index 00000000000..b84a60cd28d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/EitherNotIs.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+interface Either<out A, out B>
+interface Left<out A>: Either<A, Nothing> {
+    val value: A
+}
+interface Right<out B>: Either<Nothing, B> {
+    val value: B
+}
+
+class C1(val v1: Int)
+class C2(val v2: Int)
+
+fun _is_l(e: Either<C1, C2>): Any {
+    if (e !is Left) {
+        return e
+    }
+    return e.value.<!UNRESOLVED_REFERENCE!>v1<!>
+}
+
+fun _is_r(e: Either<C1, C2>): Any {
+    if (e !is Right) {
+        return e
+    }
+    return e.value.<!UNRESOLVED_REFERENCE!>v2<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/EitherSafeAs.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/EitherSafeAs.fir.kt
new file mode 100644
index 00000000000..a2873a79f36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/EitherSafeAs.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+interface Either<out A, out B>
+interface Left<out A>: Either<A, Nothing>
+interface Right<out B>: Either<Nothing, B>
+
+class C1(val v1: Int)
+class C2(val v2: Int)
+
+fun _as_left(e: Either<C1, C2>): Any? {
+    val v = e as? Left
+    return <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Left<C1>?>(v)
+}
+
+fun _as_right(e: Either<C1, C2>): Any? {
+    val v = e as? Right
+    return <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Right<C2>?>(v)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/EitherWhen.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/EitherWhen.fir.kt
new file mode 100644
index 00000000000..09855f1dbb6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/EitherWhen.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+interface Either<out A, out B>
+interface Left<out A>: Either<A, Nothing> {
+    val value: A
+}
+interface Right<out B>: Either<Nothing, B> {
+    val value: B
+}
+
+class C1(val v1: Int)
+class C2(val v2: Int)
+
+fun _when(e: Either<C1, C2>): Any {
+    return when (e) {
+        is Left -> e.value.<!UNRESOLVED_REFERENCE!>v1<!>
+        is Right -> e.value.<!UNRESOLVED_REFERENCE!>v2<!>
+        else -> e
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/ErrorsInSubstitution.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/ErrorsInSubstitution.fir.kt
new file mode 100644
index 00000000000..08f161ac261
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/ErrorsInSubstitution.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+interface B<T>
+interface G<T>: B<T>
+
+fun f(p: B<Foo>): Any {
+    val v = p as G
+    return checkSubtype<G<*>>(v)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/FromErrorType.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/FromErrorType.fir.kt
new file mode 100644
index 00000000000..671a9ba8318
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/FromErrorType.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+class G<T>
+
+fun foo(p: P) {
+    val v = p as G?
+    checkSubtype<G<*>>(v!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/NullableAs.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/NullableAs.fir.kt
new file mode 100644
index 00000000000..b11accdcd5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/NullableAs.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+interface Tr<T>
+interface G<T> : Tr<T>
+
+fun test(tr: Tr<String>?) {
+    val v = tr as G
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><G<String>>(v)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/NullableAsNotEnough.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/NullableAsNotEnough.fir.kt
new file mode 100644
index 00000000000..e1509febc32
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/NullableAsNotEnough.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+interface Tr
+interface G<T>
+
+fun test(tr: Tr?) {
+    val v = tr as G
+    checkSubtype<G<*>>(v)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/NullableAsNullable.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/NullableAsNullable.fir.kt
new file mode 100644
index 00000000000..110de538ed4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/NullableAsNullable.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+interface Tr<T>
+interface G<T> : Tr<T>
+
+fun test(tr: Tr<String>?) {
+    val v = tr as G?
+    // If v is not nullable, there will be a warning on this line:
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><G<String>>(v!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/NullableAsNullableNotEnough.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/NullableAsNullableNotEnough.fir.kt
new file mode 100644
index 00000000000..7fa8d3c395e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/NullableAsNullableNotEnough.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+interface Tr
+interface G<T>
+
+fun test(tr: Tr?) {
+    val v = tr as G?
+    checkSubtype<G<*>>(v!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/RedundantNullable.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/RedundantNullable.fir.kt
new file mode 100644
index 00000000000..5fd96375718
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/RedundantNullable.fir.kt
@@ -0,0 +1,4 @@
+interface B<T>
+class G<T>: B<T>
+
+fun f(b: B<String>?) = b is G??
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.fir.kt
new file mode 100644
index 00000000000..9508e3d1fd5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.fir.kt
@@ -0,0 +1,6 @@
+class P
+
+fun foo(p: P): Any {
+    val v = p as G
+    return v
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/UnrelatedAs.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/UnrelatedAs.fir.kt
new file mode 100644
index 00000000000..3c480012ddb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/UnrelatedAs.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+interface Tr
+interface G<T>
+
+fun test(tr: Tr) {
+    val v = tr as G
+    checkSubtype<G<*>>(v)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/UnrelatedColon.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/UnrelatedColon.fir.kt
new file mode 100644
index 00000000000..b63ed2cd2b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/UnrelatedColon.fir.kt
@@ -0,0 +1,7 @@
+// !CHECK_TYPE
+// NI_EXPECTED_FILE
+
+interface Tr
+interface G<T>
+
+fun test(tr: Tr) = <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><G>(tr)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/bare/UnrelatedIs.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/UnrelatedIs.fir.kt
new file mode 100644
index 00000000000..31a82acc515
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/bare/UnrelatedIs.fir.kt
@@ -0,0 +1,4 @@
+interface Tr
+interface G<T>
+
+fun test(tr: Tr) = tr is G
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/checkCastToNullableType.fir.kt b/compiler/testData/diagnostics/tests/cast/checkCastToNullableType.fir.kt
new file mode 100644
index 00000000000..1b4e9c59bc3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/checkCastToNullableType.fir.kt
@@ -0,0 +1,38 @@
+// FILE: JavaClass.java
+
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.NotNull;
+
+public class JavaClass {
+    static Integer foo() {
+        return 1;
+    }
+
+    @Nullable
+    static Integer fooN() {
+        return 1;
+    }
+
+    @NotNull
+    static Integer fooNN() {
+        return 1;
+    }
+}
+
+// FILE: test.kt
+
+fun <T, S: Any> test(x1: T, x2: T?, y1: S, y2: S?) {
+    x1 is T?
+    x2 is T?
+    y1 is S?
+    y2 is S?
+
+    val f1 = JavaClass.foo()
+    f1 is Int?
+
+    val f2 = JavaClass.fooN()
+    f2 is Int?
+
+    val f3 = JavaClass.fooNN()
+    f3 is Int?
+}
diff --git a/compiler/testData/diagnostics/tests/cast/constants.fir.kt b/compiler/testData/diagnostics/tests/cast/constants.fir.kt
new file mode 100644
index 00000000000..26ebc7dc2bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/constants.fir.kt
@@ -0,0 +1,51 @@
+fun asCall() {
+    1 as Int
+    1 as Byte
+    1 as Short
+    1 as Long
+    1 as Char
+    1 as Double
+    1 as Float
+
+    1.0 as Int
+    1.0 as Byte
+    1.0 as Short
+    1.0 as Long
+    1.0 as Char
+    1.0 as Double
+    1.0 as Float
+
+    1f as Int
+    1f as Byte
+    1f as Short
+    1f as Long
+    1f as Char
+    1f as Double
+    1f as Float
+}
+
+fun asSafe() {
+    1 as? Int
+    1 as? Byte
+    1 as? Short
+    1 as? Long
+    1 as? Char
+    1 as? Double
+    1 as? Float
+
+    1.0 as? Int
+    1.0 as? Byte
+    1.0 as? Short
+    1.0 as? Long
+    1.0 as? Char
+    1.0 as? Double
+    1.0 as? Float
+
+    1f as? Int
+    1f as? Byte
+    1f as? Short
+    1f as? Long
+    1f as? Char
+    1f as? Double
+    1f as? Float
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/isErasedAnyAndStarred.fir.kt b/compiler/testData/diagnostics/tests/cast/isErasedAnyAndStarred.fir.kt
new file mode 100644
index 00000000000..61818b7a817
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/isErasedAnyAndStarred.fir.kt
@@ -0,0 +1,3 @@
+class G<T>
+
+fun f(q: Any) = q is G<*>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/isErasedTAndStarred.fir.kt b/compiler/testData/diagnostics/tests/cast/isErasedTAndStarred.fir.kt
new file mode 100644
index 00000000000..437cb1b0ef8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/isErasedTAndStarred.fir.kt
@@ -0,0 +1,3 @@
+class G<T>
+
+fun <Q> f(q: Q) = q is G<*>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/isErasedUnrelatedAndStarred.fir.kt b/compiler/testData/diagnostics/tests/cast/isErasedUnrelatedAndStarred.fir.kt
new file mode 100644
index 00000000000..f53785c40c6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/isErasedUnrelatedAndStarred.fir.kt
@@ -0,0 +1,4 @@
+class G<T>
+interface Tr
+
+fun f(q: Tr) = q is G<*>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/kt15161.fir.kt b/compiler/testData/diagnostics/tests/cast/kt15161.fir.kt
new file mode 100644
index 00000000000..da274164691
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/kt15161.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+class Array<E>(e: E) {
+    val k = Array(1) {
+        1 as Any
+        e as Any?
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/kt614.fir.kt b/compiler/testData/diagnostics/tests/cast/kt614.fir.kt
new file mode 100644
index 00000000000..ee32fdc69fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/kt614.fir.kt
@@ -0,0 +1 @@
+fun f(a: Collection<*>) = a is List<*>?
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/neverSucceeds/CastToNotNullSuper.fir.kt b/compiler/testData/diagnostics/tests/cast/neverSucceeds/CastToNotNullSuper.fir.kt
new file mode 100644
index 00000000000..15e4ca66f5c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/neverSucceeds/CastToNotNullSuper.fir.kt
@@ -0,0 +1,8 @@
+open class A {
+    fun foo() {}
+}
+class B : A()
+
+fun test(b: B?) {
+    (b as A).foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedDirect.fir.kt b/compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedDirect.fir.kt
new file mode 100644
index 00000000000..fd1651e8fab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedDirect.fir.kt
@@ -0,0 +1,33 @@
+// !DIAGNOSTICS: -WARNING +CAST_NEVER_SUCCEEDS
+import java.lang.String as JString
+import java.lang.CharSequence as JCS
+
+fun test(
+  s: String,
+  js: JString,
+  cs: CharSequence,
+  jcs: JCS
+) {
+  s as JString
+  s as JCS
+  s as CharSequence
+  s as String
+
+  js as JString
+  js as JCS
+  js as CharSequence
+  js as String
+
+  cs as JString
+  cs as JCS
+  cs as CharSequence
+  cs as String
+
+  jcs as JString
+  jcs as JCS
+  jcs as CharSequence
+  jcs as String
+
+  jcs as Int
+  s as java.lang.Integer
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedSubtypes.fir.kt b/compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedSubtypes.fir.kt
new file mode 100644
index 00000000000..98982311d56
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedSubtypes.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -WARNING +CAST_NEVER_SUCCEEDS -ABSTRACT_MEMBER_NOT_IMPLEMENTED
+import java.lang.CharSequence as JCS
+
+class JSub: JCS
+class Sub: CharSequence
+
+fun test(
+  s: Sub,
+  js: JSub,
+  cs: CharSequence,
+  jcs: JCS
+) {
+  // js as CharSequence // - this case is not supported due to limitation in PlatformToKotlinClassMap
+  js as JCS
+
+  s as CharSequence
+  s as JCS
+
+  js as Sub
+  s as JSub
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsRelated.fir.kt b/compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsRelated.fir.kt
new file mode 100644
index 00000000000..597e86183b0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsRelated.fir.kt
@@ -0,0 +1,46 @@
+// !DIAGNOSTICS: -WARNING +CAST_NEVER_SUCCEEDS
+interface T1
+interface T2
+interface T3
+open class OC1: T1
+open class OC2: OC1(), T2
+class FC1: OC2(), T3
+interface T4: OC1
+interface T5: T2
+
+fun <TP1: OC1, TP2: T2, TP3: OC2> test(
+    t2: T2,
+    t4: T4,
+    fc1: FC1,
+    oc1: OC1,
+    oc2: OC2,
+    tp1: TP1,
+    tp2: TP2
+) {
+  fc1 as FC1
+  fc1 as OC1
+  fc1 as T1
+  fc1 as TP1
+
+  oc1 as FC1
+  oc1 as OC2
+  oc2 as OC1
+  oc1 as T2
+  oc1 as T1
+  oc1 as TP1
+  oc1 as TP2
+
+  t2 as FC1
+  t2 as OC2
+  t4 as OC1
+  t2 as T2
+  t2 as T5
+  t2 as TP2
+
+  tp1 as FC1
+  tp1 as OC1
+  tp1 as OC2
+  tp2 as T2
+  tp2 as T5
+  tp1 as TP3
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsUnrelated.fir.kt b/compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsUnrelated.fir.kt
new file mode 100644
index 00000000000..1aef98f1325
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsUnrelated.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -WARNING +CAST_NEVER_SUCCEEDS
+interface Trait1
+interface Trait2
+open class OClass1
+open class OClass2
+class FClass1
+class FClass2
+
+fun <TP1: OClass1, TP2: OClass2> test(
+  t1: Trait1,
+  oc1: OClass1,
+  fc1: FClass1,
+  tp1: TP1
+) {
+  t1 as Trait2
+  t1 as OClass2
+  t1 as FClass2
+  t1 as TP2
+
+  oc1 as Trait2
+  oc1 as OClass2
+  oc1 as FClass2
+  oc1 as TP2
+
+  fc1 as Trait2
+  fc1 as OClass2
+  fc1 as FClass2
+  fc1 as TP2
+
+  tp1 as Trait2
+  tp1 as OClass2
+  tp1 as FClass2
+  tp1 as TP2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/nothingAs.fir.kt b/compiler/testData/diagnostics/tests/cast/nothingAs.fir.kt
new file mode 100644
index 00000000000..55e07cfd39f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/nothingAs.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+
+fun TODO(): Nothing = throw java.lang.<!UNRESOLVED_REFERENCE!>IllegalStateException<!>()
+
+open class OpenClass
+class FinalClass : OpenClass()
+abstract class AbstractClass
+interface Interface
+
+fun test() {
+    TODO() as Any
+    TODO() as Any?
+    TODO() as OpenClass
+    TODO() as FinalClass
+    TODO() as AbstractClass
+    TODO() as Interface
+
+    val a = TODO() as Any
+    val b = TODO() as Any?
+    val c = TODO() as OpenClass
+    val d = TODO() as FinalClass
+    val e = TODO() as AbstractClass
+    val f = TODO() as Interface
+}
+
+fun a() = TODO() as Any
+fun b() = TODO() as Any?
+fun c() = TODO() as OpenClass
+fun d() = TODO() as FinalClass
+fun e() = TODO() as AbstractClass
+fun f() = TODO() as Interface
diff --git a/compiler/testData/diagnostics/tests/checkArguments/SpreadVarargs.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/SpreadVarargs.fir.kt
new file mode 100644
index 00000000000..10d2c17af24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/SpreadVarargs.fir.kt
@@ -0,0 +1,96 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !LANGUAGE: +ProhibitAssigningSingleElementsToVarargsInNamedForm
+
+fun <T> array1(vararg a : T) = a
+
+fun main() {
+    val a = array1("a", "b")
+    val b = array1(1, 1)
+    join(1)
+    join(1, "2")
+    join(1, "2", "3")
+    join(*1, "2")
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, *"2")
+    join(x = 1, a = "2")
+    <!INAPPLICABLE_CANDIDATE!>join<!>(x = *1, a = *"2")
+    join(x = 1, a = *a)
+    <!INAPPLICABLE_CANDIDATE!>join<!>(x = 1, a = *b)
+    join(1, *a)
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, *b)
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, *b, "3")
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, "4", *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, "4", *b, "3")
+    join(1, "4", *a)
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, "4", *a, *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>join<!>(1, "4", *a, *b, "3")
+    join(a = *a, x = 1)
+    <!INAPPLICABLE_CANDIDATE!>join<!>(a = *b, x = 1)
+    <!INAPPLICABLE_CANDIDATE!>join<!>(a = a, x = 1)
+
+    joinG<String>(1, "2")
+    joinG<String>(*1, "2")
+    <!INAPPLICABLE_CANDIDATE!>joinG<!><String>(1, *"2")
+    joinG<String>(x = 1, a = *a)
+    joinG<String>(x = 1, a = "2")
+    <!INAPPLICABLE_CANDIDATE!>joinG<!><String>(x = *1, a = *"2")
+    joinG<String>(1, *a)
+    <!INAPPLICABLE_CANDIDATE!>joinG<!><String>(1, *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>joinG<!><String>(1, "4", *a, "3")
+    joinG<String>(1, "4", *a)
+    <!INAPPLICABLE_CANDIDATE!>joinG<!><String>(1, "4", *a, *a, "3")
+    joinG<String>(a = *a, x = 1)
+
+    joinG(1, "2")
+    joinG(*1, "2")
+    <!INAPPLICABLE_CANDIDATE!>joinG<!>(1, *"2")
+    joinG(x = 1, a = *a)
+    joinG(x = 1, a = "2")
+    <!INAPPLICABLE_CANDIDATE!>joinG<!>(x = *1, a = *"2")
+    joinG(1, *a)
+    <!INAPPLICABLE_CANDIDATE!>joinG<!>(1, *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>joinG<!>(1, "4", *a, "3")
+    joinG(1, "4", *a)
+    <!INAPPLICABLE_CANDIDATE!>joinG<!>(1, "4", *a, *a, "3")
+    joinG(a = *a, x = 1)
+
+    val x1 = joinT(1, "2")
+    checkSubtype<String?>(x1)
+    val x2 = joinT(*1, "2")
+    checkSubtype<String?>(x2)
+    val x6 = joinT(1, *a)
+    checkSubtype<String?>(x6)
+    val x7 = <!INAPPLICABLE_CANDIDATE!>joinT<!>(1, *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String?>(x7)
+    val x8 = <!INAPPLICABLE_CANDIDATE!>joinT<!>(1, "4", *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String?>(x8)
+    val x9 = joinT(1, "4", *a)
+    checkSubtype<String?>(x9)
+    val x10 = <!INAPPLICABLE_CANDIDATE!>joinT<!>(1, "4", *a, *a, "3")
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String?>(x10)
+    val x11 = joinT(a = *a, x = 1)
+    checkSubtype<String?>(x11)
+    val x12 = joinT(x = 1, a = *a)
+    checkSubtype<String?>(x12)
+}
+
+fun join(x : Int, vararg a : String) : String {
+    val b = StringBuilder(x.toString())
+    for (s in a) {
+        b.append(s)
+    }
+    return b.toString()
+}
+
+fun <T> joinG(x : Int, vararg a : T) : String {
+    val b = StringBuilder(x.toString())
+    for (s in a) {
+        b.append(s)
+    }
+    return b.toString()
+}
+
+fun <T: Any> joinT(x : Int, vararg a : T) : T? {
+    return null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/checkArguments/arrayAccessSet.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/arrayAccessSet.fir.kt
new file mode 100644
index 00000000000..44253d12008
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/arrayAccessSet.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object A {
+    operator fun set(x: Int, y: String = "y", z: Double) {
+    }
+}
+
+object B {
+    operator fun set(x: Int, y: String = "y", z: Double = 3.14, w: Char = 'w', v: Boolean) {
+    }
+}
+
+object D {
+    operator fun set(x: Int, vararg y: String, z: Double) {
+    }
+}
+
+object Z {
+    operator fun set() {
+    }
+}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>A[0] = ""<!>
+    <!INAPPLICABLE_CANDIDATE!>A[0] = 2.72<!>
+
+    <!INAPPLICABLE_CANDIDATE!>B[0] = ""<!>
+    <!INAPPLICABLE_CANDIDATE!>B[0] = 2.72<!>
+    <!INAPPLICABLE_CANDIDATE!>B[0] = true<!>
+
+    <!INAPPLICABLE_CANDIDATE!>D[0] = ""<!>
+    <!INAPPLICABLE_CANDIDATE!>D[0] = 2.72<!>
+
+    <!INAPPLICABLE_CANDIDATE!>Z[0] = ""<!>
+}
diff --git a/compiler/testData/diagnostics/tests/checkArguments/arrayAccessSetTooManyArgs.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/arrayAccessSetTooManyArgs.fir.kt
new file mode 100644
index 00000000000..a3725af26f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/arrayAccessSetTooManyArgs.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A {
+    operator fun get(x: Int) {}
+    operator fun set(x: String, value: Int) {}
+
+    fun d(x: Int) {
+        <!INAPPLICABLE_CANDIDATE!>this["", 1] = 1<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/checkArguments/booleanExpressions.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/booleanExpressions.fir.kt
new file mode 100644
index 00000000000..4d6dbaa913d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/booleanExpressions.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+fun foo1(b: Boolean, c: Int) {
+    if (b && c) {}
+    if (b || c) {}
+    if (c && b) {}
+    if (c || b) {}
+}
diff --git a/compiler/testData/diagnostics/tests/checkArguments/kt1897_diagnostic_part.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/kt1897_diagnostic_part.fir.kt
new file mode 100644
index 00000000000..9634aece459
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/kt1897_diagnostic_part.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+//KT-1897 When call cannot be resolved to any function, save information about types of arguments
+
+package a
+
+fun bar() {}
+
+fun foo(i: Int, s: String) {}
+
+fun test() {
+
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(<!UNRESOLVED_REFERENCE!>xx<!>)
+
+    <!INAPPLICABLE_CANDIDATE!>bar<!> { }
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>("", 1, <!UNRESOLVED_REFERENCE!>xx<!>)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(r = <!UNRESOLVED_REFERENCE!>xx<!>, i = "", s = "")
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(i = 1, i = 1, s = 11)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>("", s = 2)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(i = "", s = 2, 33)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>("", 1) {}
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>("", 1) {} {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/checkArguments/kt1940.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/kt1940.fir.kt
new file mode 100644
index 00000000000..fa19aede37b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/kt1940.fir.kt
@@ -0,0 +1,9 @@
+//KT-1940 Exception while repeating named parameters
+package kt1940
+
+fun foo(i: Int) {}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, i = 2) //exception
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(i = 1, i = 2) //exception
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/checkArguments/overloadedFunction.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/overloadedFunction.fir.kt
new file mode 100644
index 00000000000..f3502cbdb5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/overloadedFunction.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun foo() {}
+fun foo(s: Int) {}
+
+
+fun bar(a: Any) {}
+fun bar(a: Int) {}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, 2)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>("")
+
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(1, 2)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/checkArguments/twoLambdasFunction.fir.kt b/compiler/testData/diagnostics/tests/checkArguments/twoLambdasFunction.fir.kt
new file mode 100644
index 00000000000..5e5310f50e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkArguments/twoLambdasFunction.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+fun test(x: () -> Unit, y: () -> Unit) {
+
+}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>test<!> {
+        1
+    } {
+        2
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/checkType.fir.kt b/compiler/testData/diagnostics/tests/checkType.fir.kt
new file mode 100644
index 00000000000..f1e5dad30ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/checkType.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+interface A
+interface B : A
+interface C : B
+
+fun test(b: B) {
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><B>() }
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><A>() }
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><C>() }
+}
diff --git a/compiler/testData/diagnostics/tests/classLiteral/arrays.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/arrays.fir.kt
new file mode 100644
index 00000000000..aaba90a3711
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/arrays.fir.kt
@@ -0,0 +1,7 @@
+val a01 = Array::class
+val a02 = Array<Array>::class
+val a03 = Array<Any?>::class
+val a04 = Array<Array<Any?>?>::class
+val a05 = Array<IntArray?>::class
+val a06 = kotlin.Array::class
+val a07 = kotlin.Array<IntArray?>::class
diff --git a/compiler/testData/diagnostics/tests/classLiteral/classAndObjectLiteralType.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/classAndObjectLiteralType.fir.kt
new file mode 100644
index 00000000000..5b84d1aa74f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/classAndObjectLiteralType.fir.kt
@@ -0,0 +1,16 @@
+import kotlin.reflect.KClass
+
+abstract class Base<T : Any>(val klass: KClass<out T>)
+
+class DerivedClass : Base<DerivedClass>(DerivedClass::class)
+
+object DerivedObject : Base<DerivedObject>(DerivedObject::class)
+
+enum class TestEnum {
+    TEST_ENTRY
+}
+
+val test1: KClass<DerivedClass> = DerivedClass::class
+val test2: KClass<DerivedObject> = DerivedObject::class
+val test3: KClass<TestEnum> = TestEnum::class
+val test4: KClass<out TestEnum> = TestEnum.TEST_ENTRY::class
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classLiteral/classLiteralType.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/classLiteralType.fir.kt
new file mode 100644
index 00000000000..c52949ae609
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/classLiteralType.fir.kt
@@ -0,0 +1,15 @@
+import kotlin.reflect.KClass
+
+class A
+class B
+
+val listOfString: List<String> = null!!
+val arrayOfString: Array<String> = null!!
+
+val a1 : KClass<*> = A::class
+val a2 : KClass<A> = A::class
+val a3 : KClass<B> = A::class
+val a4 : B = A::class
+
+val a5 : KClass<out List<String>> = listOfString::class
+val a6 : KClass<out Array<String>> = arrayOfString::class
diff --git a/compiler/testData/diagnostics/tests/classLiteral/expressionWithNullableType.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/expressionWithNullableType.fir.kt
new file mode 100644
index 00000000000..03b9ca0cab7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/expressionWithNullableType.fir.kt
@@ -0,0 +1,15 @@
+// FILE: J.java
+
+public interface J {
+    String platformString();
+}
+
+// FILE: test.kt
+
+fun f1(x: Int?): Any = x::class
+fun <T> f2(t: T): Any = t::class
+fun <S : String?> f3(s: S): Any = s::class
+fun <U : Any> f4(u: U?): Any = u::class
+fun f5(c: List<*>): Any = c[0]::class
+
+fun f6(j: J): Any = j.platformString()::class
diff --git a/compiler/testData/diagnostics/tests/classLiteral/genericArrays.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/genericArrays.fir.kt
new file mode 100644
index 00000000000..28e72987269
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/genericArrays.fir.kt
@@ -0,0 +1,11 @@
+import kotlin.reflect.KClass
+
+fun <T> f1(): KClass<Array<T>> = Array<T>::class
+fun <T> f2(): KClass<Array<Array<T>>> = Array<Array<T>>::class
+inline fun <reified T> f3() = Array<T>::class
+inline fun <reified T> f4() = Array<Array<T>>::class
+fun f5(): KClass<Array<Any>> = Array<*>::class
+fun f6(): KClass<Array<Int?>> = Array<Int?>::class
+fun f7() = Array<List<String>>::class
+fun f8() = Array<List<String>?>::class
+fun f9() = Array<List<*>?>::class
diff --git a/compiler/testData/diagnostics/tests/classLiteral/genericClasses.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/genericClasses.fir.kt
new file mode 100644
index 00000000000..816f61b5303
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/genericClasses.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+class A<T> {
+    class Nested<N>
+
+    inner class Inner<I>
+}
+
+val a1 = A::class
+val a2 = A<*>::class
+val a3 = A<String>::class
+val a4 = A<out String?>::class
+
+val n1 = A.Nested::class
+val n2 = A.Nested<*>::class
+
+val i1 = A.Inner::class
+val i2 = A<*>.Inner<*>::class
+val i3 = A<Int>.Inner<CharSequence>::class
+
+val m1 = Map::class
+val m2 = Map<Int, *>::class
+val m3 = Map.Entry::class
+
+val b1 = Int::class
+val b2 = Nothing::class
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classLiteral/inAnnotationArguments.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/inAnnotationArguments.fir.kt
new file mode 100644
index 00000000000..46b50f7168d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/inAnnotationArguments.fir.kt
@@ -0,0 +1,45 @@
+// !LANGUAGE: +ProhibitTypeParametersInClassLiteralsInAnnotationArguments
+
+import kotlin.reflect.KClass
+
+annotation class Ann(val k: KClass<*>)
+annotation class AnnArray(val kk: Array<KClass<*>>)
+
+object AnObject
+
+class C {
+    companion object
+}
+
+fun foo() = "foo"
+
+@Ann("foo"::class)
+fun test1() {}
+
+@Ann(String::class)
+fun test2() {}
+
+@Ann(AnObject::class)
+fun test4() {}
+
+@Ann(C::class)
+fun test5() {}
+
+@Ann(C.Companion::class)
+fun test6() {}
+
+@Ann(foo()::class)
+fun test7() {}
+
+@AnnArray(arrayOf(""::class, String::class, AnObject::class))
+fun test8() {}
+
+inline val <reified T> T.test9
+    get() = @AnnArray(arrayOf(
+        <!OTHER_ERROR!>T<!>::class,
+        Array<T>::class,
+        Array<Array<Array<T>>>::class
+    )) object {}
+
+inline val <reified T> T.test10
+    get() = @AnnArray([<!OTHER_ERROR!>T<!>::class]) object {}
diff --git a/compiler/testData/diagnostics/tests/classLiteral/inAnnotationArguments_noTypeParams.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/inAnnotationArguments_noTypeParams.fir.kt
new file mode 100644
index 00000000000..cda2d9dad0a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/inAnnotationArguments_noTypeParams.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: -ProhibitTypeParametersInClassLiteralsInAnnotationArguments
+
+import kotlin.reflect.KClass
+
+annotation class Ann(vararg val k: KClass<*>)
+
+inline val <reified T> T.test
+    get() = @Ann(
+        <!OTHER_ERROR!>T<!>::class,
+        Array<T>::class,
+        Array<Array<Array<T>>>::class
+    ) object {}
diff --git a/compiler/testData/diagnostics/tests/classLiteral/integerValueType.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/integerValueType.fir.kt
new file mode 100644
index 00000000000..53b51edd83f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/integerValueType.fir.kt
@@ -0,0 +1,11 @@
+// KT-13110 Strange type mismatch error on class literal with integer receiver expression
+
+import kotlin.reflect.KClass
+
+fun f(x: KClass<out Int>) {}
+
+fun test() {
+    f(42::class)
+    f((40 + 2)::class)
+    42::toInt
+}
diff --git a/compiler/testData/diagnostics/tests/classLiteral/nonClassesOnLHS.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/nonClassesOnLHS.fir.kt
new file mode 100644
index 00000000000..a67baf0f668
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/nonClassesOnLHS.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+class A
+
+val a1 = A?::class
+val a2 = A??::class
+
+val l1 = List<String>?::class
+val l2 = List?::class
+
+fun <T : Any> foo() {
+    val t1 = <!OTHER_ERROR!>T<!>::class
+    val t2 = <!OTHER_ERROR!>T<!>?::class
+}
+
+inline fun <reified T : Any> bar() {
+    val t3 = <!OTHER_ERROR!>T<!>?::class
+}
+
+val m = Map<String>::class
diff --git a/compiler/testData/diagnostics/tests/classLiteral/qualifiedClassLiteral.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/qualifiedClassLiteral.fir.kt
new file mode 100644
index 00000000000..d44fdcba193
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/qualifiedClassLiteral.fir.kt
@@ -0,0 +1,7 @@
+package test.foo.bar
+
+class A
+
+val k = test.foo.bar.A::class
+
+val l = java.lang.Class::class
diff --git a/compiler/testData/diagnostics/tests/classLiteral/simpleClassLiteral.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/simpleClassLiteral.fir.kt
new file mode 100644
index 00000000000..ecfe5bc206b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/simpleClassLiteral.fir.kt
@@ -0,0 +1,3 @@
+class A
+
+val k = A::class
diff --git a/compiler/testData/diagnostics/tests/classLiteral/smartCast.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/smartCast.fir.kt
new file mode 100644
index 00000000000..c398d443048
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/smartCast.fir.kt
@@ -0,0 +1,23 @@
+// KT-16291 Smart cast doesn't work when getting class of instance
+
+import kotlin.reflect.KClass
+
+class Foo {
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other === null || other::class != this::class) return false
+
+        return true
+    }
+}
+
+fun test(f: Foo?): KClass<out Foo>? = if (f != null) f::class else null
+
+fun test2(): KClass<out Foo>? {
+    var f: Foo? = null
+    if (f != null) {
+        run { f = null }
+        return f::class
+    }
+    return null
+}
diff --git a/compiler/testData/diagnostics/tests/classLiteral/typealiases.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/typealiases.fir.kt
new file mode 100644
index 00000000000..ebc38e073af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/typealiases.fir.kt
@@ -0,0 +1,15 @@
+typealias TString = String
+fun f1() = TString::class
+
+typealias TNullableString = String?
+fun f2() = TNullableString::class
+
+typealias TNullableTString = TString?
+typealias TTNullableTString = TNullableTString
+fun f3() = TTNullableTString::class
+
+inline fun <reified T> f4(b: Boolean): Any {
+    typealias X = T
+    typealias Y = T?
+    return if (b) <!UNRESOLVED_REFERENCE!>X<!>::class else <!UNRESOLVED_REFERENCE!>Y<!>::class
+}
diff --git a/compiler/testData/diagnostics/tests/classLiteral/unresolvedClass.fir.kt b/compiler/testData/diagnostics/tests/classLiteral/unresolvedClass.fir.kt
new file mode 100644
index 00000000000..61b9805ec34
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classLiteral/unresolvedClass.fir.kt
@@ -0,0 +1,2 @@
+val u = <!UNRESOLVED_REFERENCE!>Unresolved<!>::class
+val g = <!UNRESOLVED_REFERENCE!>UnresolvedGeneric<!><UnresolvedTypeArg>::class
diff --git a/compiler/testData/diagnostics/tests/classObjects/ClassObjectCannotAccessClassFields.fir.kt b/compiler/testData/diagnostics/tests/classObjects/ClassObjectCannotAccessClassFields.fir.kt
new file mode 100644
index 00000000000..a76c28aba66
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/ClassObjectCannotAccessClassFields.fir.kt
@@ -0,0 +1,9 @@
+// http://youtrack.jetbrains.net/issue/KT-20
+
+class A() {
+    val x = 1
+
+    companion object {
+        val y = <!UNRESOLVED_REFERENCE!>x<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/ClassObjectVisibility.fir.kt b/compiler/testData/diagnostics/tests/classObjects/ClassObjectVisibility.fir.kt
new file mode 100644
index 00000000000..7e4d7e0d267
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/ClassObjectVisibility.fir.kt
@@ -0,0 +1,30 @@
+package foo
+
+fun test() {
+  A.d
+  A.Companion.<!INAPPLICABLE_CANDIDATE!>f<!>
+  B.D
+  CCC
+  CCC.classObjectVar
+}
+
+class A() {
+  public companion object {
+    val d = 3
+    private object f {
+
+    }
+  }
+}
+
+class B {
+    class D {
+        private companion object
+    }
+}
+
+class CCC() {
+  private companion object {
+    val classObjectVar = 3
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/ClassObjects.fir.kt b/compiler/testData/diagnostics/tests/classObjects/ClassObjects.fir.kt
new file mode 100644
index 00000000000..4cb3dd4fc51
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/ClassObjects.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -DUPLICATE_CLASS_NAMES
+package Jet86
+
+class A {
+  companion object {
+    val x = 1
+  }
+  companion object {
+    val x = 1
+  }
+}
+
+class AA {
+  companion object {
+    val x = 1
+  }
+  companion object A {
+    val x = 1
+  }
+    companion object AA {
+    val x = 1
+  }
+}
+
+class B() {
+  val x = 12
+}
+
+object b {
+  companion object {
+    val x = 1
+  } // error
+}
+
+val a = A.x
+val c = B.<!UNRESOLVED_REFERENCE!>x<!>
+val d = b.<!UNRESOLVED_REFERENCE!>x<!>
+
+val s = System  // error
+fun test() {
+  System.out.println()
+  java.lang.System.out.println()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughClassObject.fir.kt b/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughClassObject.fir.kt
new file mode 100644
index 00000000000..e50193d6d83
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughClassObject.fir.kt
@@ -0,0 +1,51 @@
+package a
+
+class A {
+    class Nested
+    inner class Inner
+
+
+    companion object {
+
+        class Nested2
+
+        val c: Int = 1
+
+        object Obj2 {
+            val c: Int = 1
+        }
+    }
+
+    object Obj
+}
+
+object O {
+    class A
+
+    object O
+}
+
+fun f() {
+    A.c
+    A.hashCode()
+    A().Nested
+    A.Nested()
+    A().Inner()
+    A.Companion.<!UNRESOLVED_REFERENCE!>Nested<!>
+    A.Companion.<!UNRESOLVED_REFERENCE!>Inner<!>
+    A.Inner
+    A.Companion.c
+    A.Companion.Obj2
+    A.Companion.Obj2.c
+
+    A.Companion.Nested2()
+    A.Companion.c
+    A.Obj
+    A.Companion.Obj2
+    A.Obj2
+    A.Obj2.c
+    A.Nested2
+
+    O.O
+    O.A()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum_after.fir.kt b/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum_after.fir.kt
new file mode 100644
index 00000000000..999da4bb935
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum_after.fir.kt
@@ -0,0 +1,50 @@
+// !LANGUAGE: +NestedClassesInEnumEntryShouldBeInner
+
+package a
+
+
+enum class C {
+    E1, E2, E3 {
+        object O_O
+
+        fun b() {
+            O_O
+        }
+
+        class G
+    },
+
+    E4 {
+        fun c() {
+            this.<!UNRESOLVED_REFERENCE!>B<!>()
+
+            C.A()
+            A()
+            //TODO: should be resolved with error
+            this.<!UNRESOLVED_REFERENCE!>A<!>()
+        }
+    };
+
+    class A
+    inner class B
+    object O {
+        object InO
+    }
+}
+
+fun f() {
+    C.E1.A
+    C.E1.A()
+    C.E2.B()
+
+    C.E2.O
+    C.E3.O.InO
+
+    C.O
+    C.O.InO
+    C.A()
+    C.<!UNRESOLVED_REFERENCE!>B<!>()
+
+    C.E3.O_O
+    C.E3.G()
+}
diff --git a/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum_before.fir.kt b/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum_before.fir.kt
new file mode 100644
index 00000000000..278924145be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum_before.fir.kt
@@ -0,0 +1,50 @@
+// !LANGUAGE: -NestedClassesInEnumEntryShouldBeInner
+
+package a
+
+
+enum class C {
+    E1, E2, E3 {
+        object O_O
+
+        fun b() {
+            O_O
+        }
+
+        class G
+    },
+
+    E4 {
+        fun c() {
+            this.<!UNRESOLVED_REFERENCE!>B<!>()
+
+            C.A()
+            A()
+            //TODO: should be resolved with error
+            this.<!UNRESOLVED_REFERENCE!>A<!>()
+        }
+    };
+
+    class A
+    inner class B
+    object O {
+        object InO
+    }
+}
+
+fun f() {
+    C.E1.A
+    C.E1.A()
+    C.E2.B()
+
+    C.E2.O
+    C.E3.O.InO
+
+    C.O
+    C.O.InO
+    C.A()
+    C.<!UNRESOLVED_REFERENCE!>B<!>()
+
+    C.E3.O_O
+    C.E3.G()
+}
diff --git a/compiler/testData/diagnostics/tests/classObjects/InnerClassClassObject.fir.kt b/compiler/testData/diagnostics/tests/classObjects/InnerClassClassObject.fir.kt
new file mode 100644
index 00000000000..57d0532952a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/InnerClassClassObject.fir.kt
@@ -0,0 +1,25 @@
+// http://youtrack.jetbrains.net/issue/KT-449
+
+class A {
+    inner class B {
+        companion object { }
+    }
+}
+
+class B {
+    companion object {
+        class B {
+            companion object {
+                class C {
+                    companion object { }
+                }
+            }
+        }
+    }
+}
+
+class C {
+    class D {
+        companion object { }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/classObjects/builtInClassObjects.fir.kt b/compiler/testData/diagnostics/tests/classObjects/builtInClassObjects.fir.kt
new file mode 100644
index 00000000000..250ca38501f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/builtInClassObjects.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+fun box(): String {
+    try {
+        // Objects
+        val i = Int
+        val d = Double
+        val f = Float
+        val l = Long
+        val sh = Short
+        val b = Byte
+        val ch = Char
+        val st = String
+
+        test(Int)
+        test(Double)
+        test(Float)
+        test(Long)
+        test(Short)
+        test(Byte)
+        test(String)
+        test(Char)
+
+        // Common Double
+        Double.POSITIVE_INFINITY
+        Double.NEGATIVE_INFINITY
+        Double.NaN
+
+        // Common Float
+        Float.POSITIVE_INFINITY
+        Float.NEGATIVE_INFINITY
+        Float.NaN
+    }
+    catch (e: Throwable) {
+        return "Error: \n" + e
+    }
+
+    return "OK"
+}
+
+fun test(a: Any) {}
+
+
diff --git a/compiler/testData/diagnostics/tests/classObjects/classObjectHeader.fir.kt b/compiler/testData/diagnostics/tests/classObjects/classObjectHeader.fir.kt
new file mode 100644
index 00000000000..d7ff67b3a32
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/classObjectHeader.fir.kt
@@ -0,0 +1,9 @@
+package test
+
+open class ToResolve<SomeClass>(f : (Int) -> Int)
+fun testFun(a : Int) = 12
+
+class TestSome<P> {
+    companion object : ToResolve<P>({testFun(it)}) {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/classObjectInLocalClass.fir.kt b/compiler/testData/diagnostics/tests/classObjects/classObjectInLocalClass.fir.kt
new file mode 100644
index 00000000000..5b91a35a64e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/classObjectInLocalClass.fir.kt
@@ -0,0 +1,9 @@
+fun test() {
+    class A {
+        companion object {}
+    }
+
+    object {
+        companion object {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/classObjectRedeclaration.fir.kt b/compiler/testData/diagnostics/tests/classObjects/classObjectRedeclaration.fir.kt
new file mode 100644
index 00000000000..564c96200af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/classObjectRedeclaration.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -DUPLICATE_CLASS_NAMES
+package test
+
+class A {
+    object Companion
+
+    companion object
+}
+
+class B {
+    companion object Named
+
+    object Named
+}
+
+class C {
+    class Named
+
+    companion object Named
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/companionObjectOfPrivateClassVisibility.fir.kt b/compiler/testData/diagnostics/tests/classObjects/companionObjectOfPrivateClassVisibility.fir.kt
new file mode 100644
index 00000000000..28f44a7fed7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/companionObjectOfPrivateClassVisibility.fir.kt
@@ -0,0 +1,19 @@
+package test
+
+fun use() {
+    Default.create()
+
+    Explicit.create()
+}
+
+private class Default {
+    companion object {
+        fun create() = Default()
+    }
+}
+
+private class Explicit {
+    private companion object {
+        fun create() = Explicit()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/importClassInClassObject.fir.kt b/compiler/testData/diagnostics/tests/classObjects/importClassInClassObject.fir.kt
new file mode 100644
index 00000000000..bc68cc2cd51
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/importClassInClassObject.fir.kt
@@ -0,0 +1,11 @@
+package f
+
+import f.A.Companion.B
+
+class A {
+    companion object {
+        class B
+    }
+}
+
+fun test() = B()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/invisibleClassObjects.fir.kt b/compiler/testData/diagnostics/tests/classObjects/invisibleClassObjects.fir.kt
new file mode 100644
index 00000000000..c94cd61519c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/invisibleClassObjects.fir.kt
@@ -0,0 +1,51 @@
+//FILE:a.kt
+package a
+
+class A {
+    companion object {
+        fun foo() {}
+    }
+}
+
+private class B {
+    companion object {
+        fun bar() {}
+    }
+}
+
+class C {
+    private companion object {
+        fun baz() {}
+    }
+}
+
+private class D {
+    private companion object {
+        fun quux() {}
+    }
+}
+
+//FILE:b.kt
+package b
+
+import a.A
+import a.B
+import a.C
+import a.D
+
+fun test() {
+    f(A)
+    f(<!INAPPLICABLE_CANDIDATE!>B<!>)
+    f(C)
+    f(<!INAPPLICABLE_CANDIDATE!>D<!>)
+
+    A.foo()
+    <!INAPPLICABLE_CANDIDATE!>B<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+    C.baz()
+    <!INAPPLICABLE_CANDIDATE!>D<!>.<!UNRESOLVED_REFERENCE!>quux<!>()
+
+    a.A.foo()
+    a.C.baz()
+}
+
+fun f(unused: Any) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/kt3866.fir.kt b/compiler/testData/diagnostics/tests/classObjects/kt3866.fir.kt
new file mode 100644
index 00000000000..5a0f25e02f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/kt3866.fir.kt
@@ -0,0 +1,20 @@
+open class C {
+}
+
+fun C.foo() {}
+
+open class X {
+    companion object : C() {}
+}
+
+open class Y {
+    companion object : C() {}
+}
+
+fun bar() {
+    val x = X
+    x.foo()
+    X.foo()
+    (X as C).foo()
+    ((if (1<2) X else Y) as C).foo()
+}
diff --git a/compiler/testData/diagnostics/tests/classObjects/multipleDissallowedDefaultObjects.fir.kt b/compiler/testData/diagnostics/tests/classObjects/multipleDissallowedDefaultObjects.fir.kt
new file mode 100644
index 00000000000..de7b2f48423
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/multipleDissallowedDefaultObjects.fir.kt
@@ -0,0 +1,17 @@
+class A {
+    inner class I {
+        companion object A
+
+        companion object B
+
+        companion object C
+    }
+}
+
+object O {
+    companion object A
+
+    companion object B
+
+    companion object C
+}
diff --git a/compiler/testData/diagnostics/tests/classObjects/nestedClassInPrivateClassObject.fir.kt b/compiler/testData/diagnostics/tests/classObjects/nestedClassInPrivateClassObject.fir.kt
new file mode 100644
index 00000000000..5a029292302
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/nestedClassInPrivateClassObject.fir.kt
@@ -0,0 +1,15 @@
+class A {
+    private companion object {
+        class B {
+            class C {
+                companion object {
+                    fun foo() {}
+                }
+            }
+        }
+    }
+}
+
+fun f1() = A.<!INAPPLICABLE_CANDIDATE!>Companion<!>.<!UNRESOLVED_REFERENCE!>B<!>.<!UNRESOLVED_REFERENCE!>C<!>
+
+fun f2() = A.<!INAPPLICABLE_CANDIDATE!>Companion<!>.<!UNRESOLVED_REFERENCE!>B<!>.<!UNRESOLVED_REFERENCE!>C<!>.<!UNRESOLVED_REFERENCE!>foo<!>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/resolveFunctionInsideClassObject.fir.kt b/compiler/testData/diagnostics/tests/classObjects/resolveFunctionInsideClassObject.fir.kt
new file mode 100644
index 00000000000..498426201be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/resolveFunctionInsideClassObject.fir.kt
@@ -0,0 +1,9 @@
+package test
+
+class Test {
+  fun test(): Int = 12
+
+  companion object {
+    val a = <!UNRESOLVED_REFERENCE!>test<!>() // Check if resolver will be able to infer type of a variable
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject.fir.kt b/compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject.fir.kt
new file mode 100644
index 00000000000..397d1642c30
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject.fir.kt
@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE!
+// ISSUE: KT-28999
+
+fun case_1() {
+    val x = object<T> { } // type of x is <anonymous object><T>
+}
+
+fun case_2() {
+    val x = object<T : Number, K: Comparable<K>> { }
+}
+
+fun case_3() {
+    val x = object<T> <!SYNTAX!>where T : Comparable<T><!> { } // ERROR: Where clause is not allowed for objects
+}
+
+val x = object<T, K: Comparable<K>> {
+    fun test() = 10 as T // OK
+}
+
+fun case_4() {
+    val x = object<T> {
+        fun test() = 10 as T
+    }
+
+    val y = x.test() // type y is T
+}
+
+inline fun <reified T> case_5() {
+    val x = object<T> {
+        fun test() = 10 as T
+    }
+
+    val z = x.test()
+
+    if (z is T) {
+        // z is {T!! & T!!} (smart cast from T)
+        <!UNRESOLVED_REFERENCE!>println<!>(z)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject_after.fir.kt b/compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject_after.fir.kt
new file mode 100644
index 00000000000..d6f2b51acda
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject_after.fir.kt
@@ -0,0 +1,40 @@
+// !LANGUAGE: +ProhibitTypeParametersInAnonymousObjects
+// !DIAGNOSTICS: -UNUSED_VARIABLE!
+// ISSUE: KT-28999
+
+fun case_1() {
+    val x = object<T> { } // type of x is <anonymous object><T>
+}
+
+fun case_2() {
+    val x = object<T : Number, K: Comparable<K>> { }
+}
+
+fun case_3() {
+    val x = object<T> <!SYNTAX!>where T : Comparable<T><!> { } // ERROR: Where clause is not allowed for objects
+}
+
+val x = object<T, K: Comparable<K>> {
+    fun test() = 10 as T // OK
+}
+
+fun case_4() {
+    val x = object<T> {
+        fun test() = 10 as T
+    }
+
+    val y = x.test() // type y is T
+}
+
+inline fun <reified T> case_5() {
+    val x = object<T> {
+        fun test() = 10 as T
+    }
+
+    val z = x.test()
+
+    if (z is T) {
+        // z is {T!! & T!!} (smart cast from T)
+        <!UNRESOLVED_REFERENCE!>println<!>(z)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/classObjects/typeParametersInObject.fir.kt b/compiler/testData/diagnostics/tests/classObjects/typeParametersInObject.fir.kt
new file mode 100644
index 00000000000..ee288a47ee3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/classObjects/typeParametersInObject.fir.kt
@@ -0,0 +1,21 @@
+object A<T>
+object B<in T, out R>
+object C<T : Comparable<T>>
+
+class D {
+    companion object<T>
+}
+
+class E {
+    companion object<in T, out R>
+}
+
+class F {
+    companion object C<T : Comparable<T>>
+}
+
+class G {
+    companion object F<T>
+}
+
+object H<T, R>()
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/argumentsOfAnnotation.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/argumentsOfAnnotation.fir.kt
new file mode 100644
index 00000000000..9bcc0a4d510
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/argumentsOfAnnotation.fir.kt
@@ -0,0 +1,31 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ArrayLiteralsInAnnotations
+
+annotation class Foo(val a: IntArray, val b: Array<String>, val c: FloatArray)
+
+@Foo([1], ["/"], [1f])
+fun test1() {}
+
+@Foo([], [], [])
+fun test2() {}
+
+@Foo([1f], [' '], [1])
+fun test3() {}
+
+@Foo(c = [1f], b = [""], a = [1])
+fun test4() {}
+
+@Foo([1 + 2], ["Hello, " + "Kotlin"], [1 / 0f])
+fun test5() {}
+
+const val ONE = 1
+val two = 2
+
+@Foo([ONE], [], [])
+fun test6() {}
+
+@Foo([ONE + two], [], [])
+fun test7() {}
+
+@Foo([two], [], [])
+fun test8() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/argumentsOfAnnotationWithKClass.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/argumentsOfAnnotationWithKClass.fir.kt
new file mode 100644
index 00000000000..ff7c6d53274
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/argumentsOfAnnotationWithKClass.fir.kt
@@ -0,0 +1,31 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ArrayLiteralsInAnnotations
+
+import kotlin.reflect.KClass
+
+annotation class Foo(val a: Array<KClass<*>> = [])
+
+class Gen<T>
+
+annotation class Bar(val a: Array<KClass<*>> = [Int::class, Array<Int>::class, Gen::class])
+
+@Foo([])
+fun test1() {}
+
+@Foo([Int::class, String::class])
+fun test2() {}
+
+@Foo([Array::class])
+fun test3() {}
+
+@Foo([Gen<Int>::class])
+fun test4() {}
+
+@Foo([""])
+fun test5() {}
+
+@Foo([Int::class, 1])
+fun test6() {}
+
+@Bar
+fun test7() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/basicCollectionLiterals.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/basicCollectionLiterals.fir.kt
new file mode 100644
index 00000000000..dd381a3eb8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/basicCollectionLiterals.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNSUPPORTED
+
+fun test() {
+    val a = []
+    val b: Array<Int> = []
+    val c = [1, 2]
+    val d: Array<Int> = [1, 2]
+    val e: Array<String> = [1]
+
+    val f: IntArray = [1, 2]
+    val g = [f]
+}
+
+fun check() {
+    [1, 2] checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<Int>>() }
+    [""] checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<String>>() }
+
+    val f: IntArray = [1]
+    [f] checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<IntArray>>() }
+
+    [1, ""] checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<Any>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsAsPrimitiveArrays.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsAsPrimitiveArrays.fir.kt
new file mode 100644
index 00000000000..99b93413995
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsAsPrimitiveArrays.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNSUPPORTED
+
+fun basicTypes() {
+    val a: IntArray = [1]
+    val b: ByteArray = [1]
+    val c: BooleanArray = [true, false]
+    val d: CharArray = ['a']
+    val e: ShortArray = [1]
+    val f: FloatArray = [1.0f]
+    val g: LongArray = [1]
+    val h: DoubleArray = [1.0]
+}
+
+fun basicTypesWithErrors() {
+    val a: IntArray = [1.0]
+    val b: ShortArray = [1.0]
+    val c: CharArray = ["a"]
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsOutsideOfAnnotations.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsOutsideOfAnnotations.fir.kt
new file mode 100644
index 00000000000..215c070f604
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsOutsideOfAnnotations.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: +NewInference
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+fun takeArray(array: Array<String>) {}
+
+fun test() {
+    "foo bar".<!UNRESOLVED_REFERENCE!>split<!>([""])
+    <!UNRESOLVED_REFERENCE!>unresolved<!>([""])
+    takeArray([""])
+    val v = [""]
+    [""]
+    [1, 2, 3].<!UNRESOLVED_REFERENCE!>size<!>
+}
+
+fun baz(arg: Array<Int> = []) {
+    if (true) ["yes"] else {["no"]}
+}
+
+class Foo(
+    val v: Array<Int> = []
+)
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsWithVarargs.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsWithVarargs.fir.kt
new file mode 100644
index 00000000000..e395835eb6e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/collectionLiteralsWithVarargs.fir.kt
@@ -0,0 +1,41 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ArrayLiteralsInAnnotations, +ProhibitAssigningSingleElementsToVarargsInNamedForm
+
+annotation class Ann1(vararg val a: String = [])
+annotation class Ann2(vararg val a: Int = [1, 2])
+annotation class Ann3(vararg val a: Float = [1f])
+annotation class Ann4(vararg val a: String = ["/"])
+
+annotation class Ann5(vararg val a: Ann4 = [])
+annotation class Ann6(vararg val a: Ann4 = [Ann4(*["a", "b"])])
+
+annotation class Ann7(vararg val a: Long = [1L, null, ""])
+
+@Ann1(*[])
+fun test1_0() {}
+
+@Ann1(*["a", "b"])
+fun test1_1() {}
+
+@Ann1(*["a", 1, null])
+fun test1_2() {}
+
+@Ann2(*[])
+fun test2() {}
+
+@Ann3(a = *[0f, 1 / 0f])
+fun test3() {}
+
+@Ann5(Ann4(*["/"]))
+fun test5() {}
+
+@Ann6(*[])
+fun test6() {}
+
+annotation class AnnArray(val a: Array<String>)
+
+@AnnArray(*["/"])
+fun testArray() {}
+
+@Ann1([""])
+fun testVararg() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesInAnnotation.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesInAnnotation.fir.kt
new file mode 100644
index 00000000000..d193faf0ba5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesInAnnotation.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ArrayLiteralsInAnnotations
+
+annotation class Foo(
+        val a: Array<String> = ["/"],
+        val b: Array<String> = [],
+        val c: Array<String> = ["1", "2"]
+)
+
+annotation class Bar(
+        val a: Array<String> = [' '],
+        val b: Array<String> = ["", <!INFERENCE_ERROR!>''<!>],
+        val c: Array<String> = [1]
+)
+
+annotation class Base(
+        val a0: IntArray = [],
+        val a1: IntArray = [1],
+        val b1: FloatArray = [1f],
+        val b0: FloatArray = []
+)
+
+annotation class Err(
+        val a: IntArray = [1L],
+        val b: Array<String> = [1]
+)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesWithConstantsInAnnotation.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesWithConstantsInAnnotation.fir.kt
new file mode 100644
index 00000000000..d3c0b59660a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/defaultValuesWithConstantsInAnnotation.fir.kt
@@ -0,0 +1,25 @@
+// !LANGUAGE: +ArrayLiteralsInAnnotations
+
+const val ONE = 1
+
+annotation class Foo(
+        val a: IntArray = [ONE],
+        val b: IntArray = [ONE, 2, 3]
+)
+
+val TWO = 2
+
+fun getOne() = ONE
+fun getTwo() = TWO
+
+annotation class Bar(
+        val a: IntArray = [TWO],
+        val b: IntArray = [1, TWO],
+        val c: IntArray = [getOne(), getTwo()]
+)
+
+annotation class Baz(
+        val a: IntArray = [null],
+        val b: IntArray = [1, null, 2],
+        val c: IntArray = [this]
+)
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/noArrayLiteralsInAnnotationsFeature.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/noArrayLiteralsInAnnotationsFeature.fir.kt
new file mode 100644
index 00000000000..2134e0ebeae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/noArrayLiteralsInAnnotationsFeature.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: -ArrayLiteralsInAnnotations
+annotation class Foo(
+        val a: IntArray = [],
+        val b: FloatArray = [1f, 2f],
+        val c: Array<String> = ["/"]
+)
+
+@Foo
+fun test1() {}
+
+@Foo(a = [1, 2], c = ["a"])
+fun test2() {}
+
+@Foo([1], [3f], ["a"])
+fun test3() {}
+
+fun test4() {
+    [1, 2]
+}
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/noCollectionLiterals.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/noCollectionLiterals.fir.kt
new file mode 100644
index 00000000000..9683fe6ce68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/noCollectionLiterals.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+fun test(): Array<Int> {
+    [1, 2]
+    <!UNRESOLVED_REFERENCE!>[1, 2][0]<!>
+    [1, 2].<!UNRESOLVED_REFERENCE!>get<!>(0)
+
+    foo([""])
+
+    val p = [1, 2] + [3, 4]
+
+    return [1, 2]
+}
+
+fun foo(a: Array<String> = [""]) {}
+
+class A(val a: Array<Int> = [])
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/collectionLiterals/resolveToFunctionFromBuiltIns.fir.kt b/compiler/testData/diagnostics/tests/collectionLiterals/resolveToFunctionFromBuiltIns.fir.kt
new file mode 100644
index 00000000000..68aef2e6c7b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/collectionLiterals/resolveToFunctionFromBuiltIns.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +ArrayLiteralsInAnnotations
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNSUPPORTED
+
+annotation class Anno(val a: Array<String> = [""], val b: IntArray = [])
+
+@Anno([], [])
+fun test() {}
+
+fun arrayOf(): Array<Int> = TODO()
+fun intArrayOf(): Array<Int> = TODO()
+
+fun local() {
+    val a1: IntArray = [1, 2]
+    val a2: IntArray = []
+
+    val s1: Array<String> = [""]
+    val s2: Array<String> = []
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/afterInitialization.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/afterInitialization.fir.kt
new file mode 100644
index 00000000000..269ed78f62b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/afterInitialization.fir.kt
@@ -0,0 +1,6 @@
+class My(val x: Int) {
+    val y: Int = x + 3
+    val z: Int? = foo()
+
+    fun foo() = if (x >= 0) x else if (y >= 0) y else null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/aliencall.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/aliencall.fir.kt
new file mode 100644
index 00000000000..f2582aebd28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/aliencall.fir.kt
@@ -0,0 +1,29 @@
+fun foo() = 42
+
+class Your {
+    fun bar() = 13
+}
+
+class My {
+    val your = Your()
+
+    val x = foo()
+
+    val y = Your().bar()
+
+    val z = your.bar()
+
+    // This extension function also can use our properties,
+    // so the call is also dangerous
+    val w = your.gav()
+
+    val v = Your().gav()
+
+    val t = your.other()
+
+    val r = Your().other()
+
+    fun Your.gav() = if (your.bar() == 0) t else r
+}
+
+fun Your.other() = "3"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/assignment.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/assignment.fir.kt
new file mode 100644
index 00000000000..02d1cb803f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/assignment.fir.kt
@@ -0,0 +1,11 @@
+class My {
+    val x: String
+
+    constructor() {
+        val temp = this
+        x = bar(temp)
+    }
+
+}
+
+fun bar(arg: My) = arg.x
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/backing.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/backing.fir.kt
new file mode 100644
index 00000000000..57e7fa3c18a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/backing.fir.kt
@@ -0,0 +1,30 @@
+class My {
+    var x = 1
+        set(value) {
+            field = value
+        }
+
+    var y: Int = 1
+        set(value) {
+            field = value + if (w == "") 0 else 1
+        }
+
+    var z: Int = 2
+        set(value) {
+            field = value + if (w == "") 1 else 0
+        }
+
+    var m: Int = 2
+        set
+
+    init {
+        x = 3
+        m = 6
+
+        // Writing properties using setters is dangerous
+        y = 4
+        this.z = 5
+    }
+
+    val w = "6"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/basic.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/basic.fir.kt
new file mode 100644
index 00000000000..48bfe299b62
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/basic.fir.kt
@@ -0,0 +1,13 @@
+class My {
+    val x: String
+
+    constructor() {
+        val y = bar(this)
+        val z = foo()
+        x = "$y$z"
+    }
+
+    fun foo() = x
+}
+
+fun bar(arg: My) = arg.x
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/companion.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/companion.fir.kt
new file mode 100644
index 00000000000..5b0313198a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/companion.fir.kt
@@ -0,0 +1,19 @@
+class My {
+
+    val x = foo()
+
+    val w = bar()
+
+    fun foo() = 0
+
+    companion object {
+        
+        val y = <!UNRESOLVED_REFERENCE!>foo<!>()
+
+        val u = bar()
+
+        val z: String? = bar()
+
+        fun bar() = "1"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/comparison.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/comparison.fir.kt
new file mode 100644
index 00000000000..0a387c86d4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/comparison.fir.kt
@@ -0,0 +1,10 @@
+val instance = My()
+
+class My {
+    val equalsInstance = (this == instance)
+
+    val isInstance = if (this === instance) "true" else "false"
+
+    override fun equals(other: Any?) =
+            other is My && isInstance.hashCode() == other.isInstance.hashCode()
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/delegate.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/delegate.fir.kt
new file mode 100644
index 00000000000..87b106a035c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/delegate.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class Delegate(val x: Int) {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int = x
+}
+
+class My {
+    val x: Int by Delegate(this.foo())
+
+    fun foo(): Int = x
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/derived.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/derived.fir.kt
new file mode 100644
index 00000000000..c722cd64575
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/derived.fir.kt
@@ -0,0 +1,11 @@
+open class Base(val x: String) {
+    fun foo() = bar()
+
+    open fun bar() = -1
+}
+
+class Derived(x: String): Base(x) {
+    // It's still dangerous: we're not sure that foo() does not call some open function inside
+    val y = foo()
+    val z = x
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/derivedProperty.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/derivedProperty.fir.kt
new file mode 100644
index 00000000000..be7f6b0fc58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/derivedProperty.fir.kt
@@ -0,0 +1,11 @@
+interface Base {
+    val x: Int
+}
+
+open class Impl(override val x: Int) : Base {
+    init {
+        if (this.x != 0) foo()
+    }
+}
+
+fun foo() {}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/getset.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/getset.fir.kt
new file mode 100644
index 00000000000..49468747f35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/getset.fir.kt
@@ -0,0 +1,26 @@
+class My(var x: String) {
+
+    var y: String
+        get() = if (x != "") x else z
+        set(arg) {
+            if (arg != "") x = arg
+        }
+
+    val z: String
+
+    var d: String = ""
+        get
+        set
+
+    val z1: String
+
+    init {
+        d = "d"
+        if (d != "") z1 = this.d else z1 = d
+
+        // Dangerous: setter!
+        y = "x"
+        // Dangerous: getter!
+        if (y != "") z = this.y else z = y
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/init.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/init.fir.kt
new file mode 100644
index 00000000000..e64714ea474
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/init.fir.kt
@@ -0,0 +1,9 @@
+class My {
+    val x: String
+
+    init {
+        x = foo()
+    }
+
+    fun foo(): String = x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/initializerWithSecondaryConstructor.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/initializerWithSecondaryConstructor.fir.kt
new file mode 100644
index 00000000000..bcfc88c8f58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/initializerWithSecondaryConstructor.fir.kt
@@ -0,0 +1,20 @@
+
+private const val A = 0L
+private val B = 0L
+private fun sample() = 0L
+
+private class PrivateClass
+
+class Foo {
+    var bar: Long = 0
+    private var other: PrivateClass? = null
+
+    init {
+        bar = A
+        bar = B
+        bar = sample()
+        other = PrivateClass()
+    }
+
+    constructor()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/initwithgetter.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/initwithgetter.fir.kt
new file mode 100644
index 00000000000..87577c486b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/initwithgetter.fir.kt
@@ -0,0 +1,19 @@
+class My {
+    val x: Int
+        get() = field + if (z != "") 1 else 0
+
+    val y: Int
+        get() = field - if (z == "") 0 else 1
+
+    val w: Int
+
+    init {
+        // Safe, val never has a setter
+        x = 0
+        this.y = 0
+        // Unsafe
+        w = this.x + y
+    }
+
+    val z = "1"
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/inspection.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/inspection.fir.kt
new file mode 100644
index 00000000000..deb9cb25b2b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/inspection.fir.kt
@@ -0,0 +1,56 @@
+class First {
+    val x: String
+
+    init {
+        use(this) // NPE! Leaking this
+        x = foo() // NPE! Own function
+    }
+
+    fun foo() = x
+}
+
+fun use(first: First) = first.x.hashCode()
+
+abstract class Second {
+    val x: String
+
+    init {
+        use(this) // Leaking this in non-final
+        x = bar() // Own function in non-final
+        foo()     // Non-final function call
+    }
+
+    private fun bar() = foo()
+
+    abstract fun foo(): String
+}
+
+fun use(second: Second) = second.x
+
+class SecondDerived : Second() {
+    val y = x // null!
+
+    override fun foo() = y
+}
+
+open class Third {
+    open var x: String
+
+    constructor() {
+        x = "X" // Non-final property access
+    }
+}
+
+class ThirdDerived : Third() {
+    override var x: String = "Y"
+        set(arg) { field = "$arg$y" }
+
+    val y = ""
+}
+
+class Fourth {
+    val x: String
+        get() = y
+
+    val y = x // null!
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/lambdaInObject.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/lambdaInObject.fir.kt
new file mode 100644
index 00000000000..eb4204ba880
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/lambdaInObject.fir.kt
@@ -0,0 +1,18 @@
+interface Wise {
+    fun doIt(): Int
+}
+
+fun Wise(f: () -> Int) = object: Wise {
+    override fun doIt() = f()
+}
+
+class My {
+    // Still dangerous (???), nobogy can guarantee what Wise() will do with this lambda
+    val x = Wise { foo() }
+
+    val y = 42
+
+    fun foo() = y
+
+    fun bar() = x.doIt()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/lateInit.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/lateInit.fir.kt
new file mode 100644
index 00000000000..87b435651e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/lateInit.fir.kt
@@ -0,0 +1,15 @@
+class WithLateInit {
+    lateinit var x: String
+
+    fun init(xx: String) {
+        x = xx
+    }
+
+    init {
+        // This is obviously a bug,
+        // but with lateinit we explicitly want it to occur in runtime
+        use()
+    }
+
+    fun use() = x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/localObject.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/localObject.fir.kt
new file mode 100644
index 00000000000..c4f8951c4f0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/localObject.fir.kt
@@ -0,0 +1,19 @@
+open class Wise {
+
+    val x = 1
+
+    open fun doIt(): Int = 42
+}
+
+class My {
+
+    fun foo(): Int {
+        val wise = object: Wise() {
+            var xx = 1
+            override fun doIt() = super.doIt() + bar(this) + xx
+        }
+        return wise.doIt()
+    }   
+}
+
+fun bar(wise: Wise): Int = wise.x
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/multipleAreNull.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/multipleAreNull.fir.kt
new file mode 100644
index 00000000000..c3d2c6276eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/multipleAreNull.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Context
+class Point
+
+class Example {
+    constructor(context: Context?)
+    constructor(context: Context?, arg1: Int)
+    constructor(context: Context?, arg1: Int, arg2: Int)
+    constructor(context: Context?, arg1: Int, arg2: Int, arg3: Int)
+
+    var condition: Boolean = false
+    private var index = newIndex(condition)
+    private fun newIndex(zero: Boolean) = if (zero) 0 else 1
+
+    private lateinit var latePoint1: Point
+    private lateinit var latePoint2: Point
+
+    private val point1 = Point()
+    private val point2 = Point()
+    private val point3 = Point()
+    private val point4 = Point()
+    private var nullPoint: Point? = null
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/nobacking.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/nobacking.fir.kt
new file mode 100644
index 00000000000..0d62f81b31f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/nobacking.fir.kt
@@ -0,0 +1,12 @@
+class My {
+
+    val x: Int
+        get() = 1
+
+    init {
+        // x has no backing field, so the call is safe
+        foo()
+    }
+
+    fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/open.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/open.fir.kt
new file mode 100644
index 00000000000..2917319c9ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/open.fir.kt
@@ -0,0 +1,34 @@
+open class Base {
+    init {
+        register(this)
+        foo()
+    }
+
+    open fun foo() {}
+}
+
+fun register(arg: Base) {
+    arg.foo()
+}
+
+class Derived(val x: Int) : Base() {
+    override fun foo() {
+        x.hashCode() // NPE in Base constructor
+    }
+}
+
+enum class MyEnum {
+    FIRST() {
+        val x: Int = 42
+
+        override fun foo() {
+            x.hashCode() // NPE in MyEnum constructor
+        }
+    };
+
+    init {
+        foo()
+    }
+
+    abstract fun foo()
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/openProperty.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/openProperty.fir.kt
new file mode 100644
index 00000000000..35a6ae666fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/openProperty.fir.kt
@@ -0,0 +1,14 @@
+open class Base {
+    open var x: Int
+
+    open var y: Int
+
+    constructor() {
+        x = 42
+        this.y = 24
+        val temp = this.x
+        this.x = y
+        y = temp
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/outer.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/outer.fir.kt
new file mode 100644
index 00000000000..a1027c124db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/outer.fir.kt
@@ -0,0 +1,11 @@
+class Outer {
+
+    fun foo() = 1
+
+    inner class Inner {
+
+        val x = this@Outer.foo()
+
+        val y = foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/property.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/property.fir.kt
new file mode 100644
index 00000000000..452aa636375
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/property.fir.kt
@@ -0,0 +1,5 @@
+class My(x: String) {
+    val y: String = foo(x)
+
+    fun foo(x: String) = "$x$y"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/propertyAccess.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/propertyAccess.fir.kt
new file mode 100644
index 00000000000..33054eb8a4c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/propertyAccess.fir.kt
@@ -0,0 +1,7 @@
+class My {
+    val x: Int
+
+    constructor(x: Int) {
+        this.x = x
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/constructorConsistency/twoSecondaryConstructors.fir.kt b/compiler/testData/diagnostics/tests/constructorConsistency/twoSecondaryConstructors.fir.kt
new file mode 100644
index 00000000000..3ecbd358560
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/constructorConsistency/twoSecondaryConstructors.fir.kt
@@ -0,0 +1,12 @@
+fun use(x: Any?) = x
+
+class Eap {
+    private val foo = toString()
+
+    constructor(foo: Int) {
+        use(foo)
+    }
+    constructor(foo: String) {
+        use(foo)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedOrReassignedVariables.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedOrReassignedVariables.fir.kt
new file mode 100644
index 00000000000..c63bea9bf28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedOrReassignedVariables.fir.kt
@@ -0,0 +1,349 @@
+// !WITH_NEW_INFERENCE
+package uninitialized_reassigned_variables
+
+fun doSmth(s: String) {}
+fun doSmth(i: Int) {}
+
+// ------------------------------------------------
+// uninitialized variables
+
+fun t1(b : Boolean) {
+    val v : Int
+    if (v == 0) {}
+
+    var u: String
+    if (b) {
+        u = "s"
+    }
+    doSmth(u)
+
+    var r: String
+    if (b) {
+        r = "s"
+    }
+    else {
+        r = "tg"
+    }
+    doSmth(r)
+
+    var t: String
+    if (b)
+        doSmth(t)
+    else
+        t = "ss"
+    doSmth(t) //repeat for t
+
+    val i = 3
+    doSmth(i)
+    if (b) {
+        return;
+    }
+    doSmth(i)
+    if (i is Int) {
+        return;
+    }
+}
+
+fun t2() {
+    val s = "ss"
+
+    for (i in 0..2) {
+        doSmth(s)
+    }
+}
+
+class A() {}
+
+fun t4(a: A) {
+    a = A()
+}
+
+// ------------------------------------------------
+// reassigned vals
+
+fun t1() {
+    val a : Int = 1
+    a = 2
+
+    var b : Int = 1
+    b = 3
+}
+
+enum class ProtocolState {
+  WAITING {
+    override fun signal() = ProtocolState.TALKING
+  },
+
+  TALKING {
+    override fun signal() = ProtocolState.WAITING
+  };
+
+  abstract fun signal() : ProtocolState
+}
+
+fun t3() {
+   val x: ProtocolState = ProtocolState.WAITING
+   x = x.signal()
+   x = x.signal() //repeat for x
+}
+
+fun t4() {
+    val x = 1
+    <!VARIABLE_EXPECTED!>x<!> += 2
+    val y = 3
+    <!VARIABLE_EXPECTED!>y<!> *= 4
+    var z = 5
+    z -= y
+}
+
+fun t5() {
+    for (i in 0..2) {
+        <!VARIABLE_EXPECTED!>i<!> += 1
+        fun t5() {
+            <!VARIABLE_EXPECTED!>i<!> += 3
+        }
+    }
+}
+
+// ------------------------------------------------
+// backing fields
+
+var x = 10
+val y = 10
+val z = 10
+
+class AnonymousInitializers(var a: String, val b: String) {
+    init {
+        a = "30"
+        a = "s"
+
+        b = "3"
+        b = "tt" //repeat for b
+    }
+
+    val i: Int
+    init {
+        i = 121
+    }
+
+    init {
+        x = 11
+        z = 10
+    }
+
+    val j: Int
+    get() = 20
+
+    init {
+        i = 13
+        j = 34
+    }
+
+    val k: String
+    init {
+        if (1 < 3) {
+            k = "a"
+        }
+        else {
+            k = "b"
+        }
+    }
+
+    val l: String
+    init {
+        if (1 < 3) {
+            l = "a"
+        }
+        else {
+            l = "b"
+        }
+    }
+
+    val o: String
+    init {
+        if (1 < 3) {
+            o = "a"
+        }
+    }
+
+    var m: Int = 30
+
+    init {
+        m = 400
+    }
+
+    val n: Int
+
+    init {
+        while (n == 0) {
+        }
+        n = 10
+        while (n == 0) {
+        }
+    }
+
+    var p = 1
+    init {
+        p++
+    }
+}
+
+fun reassignFunParams(a: Int) {
+    a = 1
+}
+
+open class Open(a: Int, w: Int) {}
+
+class LocalValsVsProperties(val a: Int, w: Int) : Open(a, w) {
+    val x : Int
+    val y : Int
+    init {
+        x = 1
+        val b = x
+    }
+    val b = a
+
+    fun foo() {
+        val r : Int
+        doSmth(x)
+        doSmth(y)
+        doSmth(r)
+        doSmth(a)
+    }
+    var xx = w
+    var yy : Int
+    init {
+        <!VARIABLE_EXPECTED!>w<!> += 1
+        yy = w
+    }
+}
+
+class Outer() {
+    val a : Int
+    var b : Int
+
+    init {
+        a = 1
+        b = 1
+    }
+
+    inner class Inner() {
+        init {
+            a++
+            b++
+        }
+    }
+
+    fun foo() {
+        a++
+        b++
+    }
+}
+
+class ForwardAccessToBackingField() { //kt-147
+    val a = a // error
+    val b = c // error
+    val c = 1
+}
+
+class ClassObject() {
+    companion object {
+        val x : Int
+
+        init {
+            x = 1
+        }
+
+
+        fun foo() {
+            val a : Int
+            doSmth(a)
+        }
+    }
+}
+
+fun foo() {
+    val a = object {
+        val x : Int
+        val y : Int
+        val z : Int
+        init {
+            x = 1
+            z = 3
+        }
+        fun foo() {
+            y = 10
+            z = 13
+        }
+    }
+}
+
+class TestObjectExpression() {
+    val a : Int
+    fun foo() {
+        val a = object {
+            val x : Int
+            val y : Int
+            init {
+                if (true)
+                    x = 12
+                else
+                    x = 1
+            }
+            fun inner1() {
+                y = 101
+                a = 231
+            }
+            fun inner2() {
+                y = 101
+                a = 231
+            }
+        }
+    }
+}
+
+
+
+object TestObjectDeclaration {
+    val x : Int
+    val y : Int
+    init {
+        x = 1
+    }
+
+    fun foo() {
+        y = 10
+        val i: Int
+        if (1 < 3) {
+            i = 10
+        }
+        doSmth(i)
+    }
+}
+
+fun func() {
+    val b = 1
+    val a = object {
+        val x = b
+        init {
+            b = 4
+        }
+    }
+}
+
+// ------------------------------------------------
+// dot qualifiers
+class M() {
+    val x = 11
+    var y = 12
+}
+
+fun test(m : M) {
+    m.x = 23
+    m.y = 23
+}
+
+fun test1(m : M) {
+    m.x++
+    m.y--
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/assignedInFinally.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/assignedInFinally.fir.kt
new file mode 100644
index 00000000000..46dc8b1e6ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/assignedInFinally.fir.kt
@@ -0,0 +1,10 @@
+fun test5() {
+    var a: Int
+    try {
+        a = 3
+    }
+    finally {
+        a = 5
+    }
+    a.hashCode()
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/assignmentInLocalsInConstructor.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/assignmentInLocalsInConstructor.fir.kt
new file mode 100644
index 00000000000..d59def7d63d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/assignmentInLocalsInConstructor.fir.kt
@@ -0,0 +1,67 @@
+// Tests for KT-13597 (val assignment inside local object in constructor)
+
+class Test {
+    val a: String
+
+    init {
+        val t = object {
+            fun some() {
+                // See KT-13597
+                a = "12"
+            }
+        }
+
+        a = "2"
+        t.some()
+    }
+}
+
+class Test2 {
+    init {
+        val t = object {
+            fun some() {
+                a = "12"
+            }
+        }
+
+        a = "2"
+        t.some()
+    }
+
+    val a: String
+}
+
+// Tests for KT-14381 (val assignment inside lambda in constructor)
+
+fun <T> exec(f: () -> T): T = f()
+
+class Test4 {
+    val a: String
+
+    init {
+        exec {
+            // See KT-14381
+            a = "12"
+        }
+        a = "34"
+    }
+}
+
+// Additional tests to prevent something broken
+
+class Test5 {
+
+    val y: Int
+
+    val z: String
+
+    init {
+        val x: String
+        <!UNRESOLVED_REFERENCE!>x<!> = ""
+        z = <!UNRESOLVED_REFERENCE!>x<!>
+    }
+
+    constructor(y: Int) {
+        this.y = y
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/backingFieldInsideGetter_after.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/backingFieldInsideGetter_after.fir.kt
new file mode 100644
index 00000000000..27b22820416
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/backingFieldInsideGetter_after.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +RestrictionOfValReassignmentViaBackingField
+
+package a
+
+import java.util.HashSet
+
+val a: MutableSet<String>? = null
+    get() {
+        if (a == null) {
+            field = HashSet()
+        }
+        return a
+    }
+
+class R {
+    val b: String? = null
+        get() {
+            if (b == null) {
+                field = "b"
+            }
+            return b
+        }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/backingFieldInsideGetter_before.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/backingFieldInsideGetter_before.fir.kt
new file mode 100644
index 00000000000..f2d5f28e3aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/backingFieldInsideGetter_before.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: -RestrictionOfValReassignmentViaBackingField
+
+package a
+
+import java.util.HashSet
+
+val a: MutableSet<String>? = null
+    get() {
+        if (a == null) {
+            field = HashSet()
+        }
+        return a
+    }
+
+class R {
+    val b: String? = null
+        get() {
+            if (b == null) {
+                field = "b"
+            }
+            return b
+        }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakContinueInTryFinally.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakContinueInTryFinally.fir.kt
new file mode 100644
index 00000000000..cd3d5ee92ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakContinueInTryFinally.fir.kt
@@ -0,0 +1,24 @@
+fun foo() {
+    outer@while (true) {
+        try {
+            while (true) {
+                continue@outer
+            }
+        } finally {
+            break
+        }
+    }
+    "OK".hashCode()
+}
+
+fun bar(): String {
+    outer@while (true) {
+        try {
+            while (true) {
+                continue@outer
+            }
+        } finally {
+            return "OK"
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakInsideLocal.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakInsideLocal.fir.kt
new file mode 100644
index 00000000000..1cd78622a47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakInsideLocal.fir.kt
@@ -0,0 +1,86 @@
+fun test() {
+    while (true) {
+        fun local1() {
+            break
+        }
+    }
+}
+
+fun test2() {
+    while (true) {
+        {
+            continue
+        }
+    }
+}
+
+fun test3() {
+    while (true) {
+        class LocalClass {
+            init {
+                continue
+            }
+
+            fun foo() {
+                break
+            }
+        }
+    }
+}
+
+fun test4() {
+    while (true) {
+        object: Any() {
+            init {
+                break
+            }
+        }
+    }
+}
+
+fun test5() {
+    while (true) {
+        class LocalClass(val x: Int) {
+            constructor() : this(42) {
+                break
+            }
+            constructor(y: Double) : this(y.toInt()) {
+                continue
+            }
+        }
+    }
+}
+
+fun test6() {
+    while (true) {
+        class LocalClass(val x: Int) {
+            init {
+                break
+            }
+            init {
+                continue
+            }
+        }
+    }
+}
+
+fun test7() {
+    while (true) {
+        class LocalClass {
+            val x: Int = if (true) {
+                break
+            }
+            else {
+                continue
+            }
+        }
+    }
+}
+
+fun test8() {
+    while (true) {
+        class LocalClass(val x: Int) {
+            constructor() : this(if (true) { 42 } else { break })
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakOrContinueInLoopCondition.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakOrContinueInLoopCondition.fir.kt
new file mode 100644
index 00000000000..da8fe3d06ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/breakOrContinueInLoopCondition.fir.kt
@@ -0,0 +1,34 @@
+fun test() {
+
+    l@ for (i in if (true) 1..10 else continue@l) {}
+    for (i in if (true) 1..10 else continue) {}
+
+    while (break) {}
+    l@ while (break@l) {}
+
+    do {} while (continue)
+    l@ do {} while (continue@l)
+
+    //KT-5704
+    var i = 0
+    while (if(i++ == 10) break else continue) {}
+}
+
+fun test2(b: Boolean) {
+    while (b) {
+        while (break) {}
+    }
+
+    do {
+        while (continue) {}
+    } while (b)
+
+    while (b) {
+        do {} while (break)
+    }
+
+    for (i in 1..10) {
+        for (j in if (true) 1..10 else continue) {
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/checkInnerLocalDeclarations.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/checkInnerLocalDeclarations.fir.kt
new file mode 100644
index 00000000000..1e5f0e60de9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/checkInnerLocalDeclarations.fir.kt
@@ -0,0 +1,12 @@
+package c
+
+fun test() {
+    val x = 10
+    fun inner1() {
+        fun inner2() {
+            fun inner3() {
+                val y = x
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/checkPropertyAccessor.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/checkPropertyAccessor.fir.kt
new file mode 100644
index 00000000000..98f5d3afdc9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/checkPropertyAccessor.fir.kt
@@ -0,0 +1,38 @@
+package d
+
+val a: Int
+    get() {
+        val b: Int
+        val c: Int
+        42
+
+        fun bar(): Int {
+            val d: Int
+            42
+            return d
+        }
+
+        return b
+    }
+
+class A {
+    val a: Int
+        get() {
+            val b: Int
+            val c: Int
+            42
+            return b
+        }
+
+    fun foo() {
+        class B {
+            val a: Int
+                get() {
+                    val b: Int
+                    val c: Int
+                    42
+                    return b
+                }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/constructorPropertyInterdependence.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/constructorPropertyInterdependence.fir.kt
new file mode 100644
index 00000000000..89a0f558c6d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/constructorPropertyInterdependence.fir.kt
@@ -0,0 +1,8 @@
+// See KT-12809
+open class A(val a: Any) {
+    override fun toString() = a.toString()
+}
+
+object B : A(B.foo) { // call B.foo should be not-allowed
+    val foo = 4
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commasAndWhitespaces.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commasAndWhitespaces.fir.kt
new file mode 100644
index 00000000000..7cd5ee47a01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commasAndWhitespaces.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun testCommasAndWhitespaces() {
+    fun bar(i: Int, s: String, x: Any) {}
+
+    bar( 1 , todo() , "" )
+}
+
+fun todo(): Nothing = throw Exception()
+
+
+
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.fir.kt
new file mode 100644
index 00000000000..1eb8bff5c0a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/commentsInDeadCode.fir.kt
@@ -0,0 +1,22 @@
+package a
+
+fun test1() {
+    bar(
+        11,
+        todo(),//comment1
+        ""//comment2
+    )
+}
+
+fun test2() {
+    bar(11, todo()/*comment1*/, ""/*comment2*/)
+}
+fun test3() {
+    bar(11, l@(todo()/*comment*/), "")
+}
+
+fun todo(): Nothing = throw Exception()
+
+fun bar(i: Int, s: String, a: Any) {}
+
+
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInInvokeCall.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInInvokeCall.fir.kt
new file mode 100644
index 00000000000..a0c9af7bfbe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInInvokeCall.fir.kt
@@ -0,0 +1,11 @@
+fun testInvoke() {
+    operator fun Nothing.invoke(): Nothing = this
+    todo()()
+}
+
+fun testInvokeWithLambda() {
+    operator fun Nothing.invoke(i: Int, f: () -> Int) = f
+    todo()(1){ 42 }
+}
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInReceiver.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInReceiver.fir.kt
new file mode 100644
index 00000000000..4056042ba8b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCallInReceiver.fir.kt
@@ -0,0 +1,11 @@
+fun test11() {
+    fun Any.bar(i: Int) {}
+    todo().bar(1)
+}
+
+fun test12() {
+    fun Any.bar(i: Int) {}
+    todo()?.bar(1)
+}
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeDifferentExamples.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeDifferentExamples.fir.kt
new file mode 100644
index 00000000000..02e113dc355
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeDifferentExamples.fir.kt
@@ -0,0 +1,168 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+fun t1() : Int{
+  return 0
+  1
+}
+
+fun t1a() : Int {
+  return
+  return 1
+  1
+}
+
+fun t1b() : Int {
+  return 1
+  return 1
+  1
+}
+
+fun t1c() : Int {
+  return 1
+  return
+  1
+}
+
+fun t2() : Int {
+  if (1 > 2)
+    return 1
+  else return 1
+  1
+}
+
+fun t2a() : Int {
+  if (1 > 2) {
+    return 1
+    1
+  } else { return 1
+    2
+  }
+  1
+}
+
+fun t3() : Any {
+  if (1 > 2)
+    return 2
+  else return ""
+  1
+}
+
+fun t4(a : Boolean) : Int {
+  do {
+    return 1
+  }
+  while (a)
+  1
+}
+
+fun t4break(a : Boolean) : Int {
+  do {
+    break
+  }
+  while (a)
+  return 1
+}
+
+fun t5() : Int {
+  do {
+    return 1
+    2
+  }
+  while (1 > 2)
+  return 1
+}
+
+fun t6() : Int {
+  while (1 > 2) {
+    return 1
+    2
+  }
+  return 1
+}
+
+fun t6break() : Int {
+  while (1 > 2) {
+    break
+    2
+  }
+  return 1
+}
+
+fun t7(b : Int) : Int {
+  for (i in 1..b) {
+    return 1
+    2
+  }
+  return 1
+}
+
+fun t7break(b : Int) : Int {
+  for (i in 1..b) {
+    return 1
+    2
+  }
+  return 1
+}
+
+fun t7() : Int {
+  try {
+    return 1
+    2
+  }
+  catch (e : Any) {
+    2
+  }
+  return 1 // this is OK, like in Java
+}
+
+fun t8() : Int {
+  try {
+    return 1
+    2
+  }
+  catch (e : Any) {
+    return 1
+    2
+  }
+  return 1
+}
+
+fun blockAndAndMismatch() : Boolean {
+  (return true) || (return false)
+  return true
+}
+
+fun tf() : Int {
+  try {return 1} finally{return 1}
+  return 1
+}
+
+fun failtest(a : Int) : Int {
+  if (fail() || true) {
+
+  }
+  return 1
+}
+
+fun foo(a : Nothing) : Unit {
+  1
+  a
+  2
+}
+
+fun fail() : Nothing {
+  throw java.lang.<!UNRESOLVED_REFERENCE!>RuntimeException<!>()
+}
+
+fun nullIsNotNothing() : Unit {
+    val x : Int? = 1
+    if (x != null) {
+         return
+    }
+    fail()
+}
+
+fun returnInWhile(a: Int) {
+    do {return}
+    while (1 > a)
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeFromDifferentSources.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeFromDifferentSources.fir.kt
new file mode 100644
index 00000000000..d2c13049fb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeFromDifferentSources.fir.kt
@@ -0,0 +1,23 @@
+package c
+
+fun test1() {
+    val r: Nothing = null!!
+}
+
+fun test2(a: A) {
+    a + a
+    bar()
+}
+
+fun test3() {
+    null!!
+    bar()
+}
+
+fun throwNPE(): Nothing = null!!
+
+class A {
+    operator fun plus(a: A): Nothing = throw Exception()
+}
+
+fun bar() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInArrayAccess.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInArrayAccess.fir.kt
new file mode 100644
index 00000000000..74ab2d9781b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInArrayAccess.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun testArrayAccess1(array: Array<Any>) {
+    array[todo()]
+}
+
+fun testArrayAccess2() {
+    operator fun Nothing.get(i: Int, s: String) {}
+    todo()[1, ""]
+}
+
+fun testAraryAccess3() {
+    operator fun Nothing.get(n: Nothing) {}
+    todo()[todo()]
+}
+
+fun testArrayAssignment1(array: Array<Any>) {
+    array[todo()] = 11
+}
+
+fun testArrayAssignment2(array: Array<Any>) {
+    array[1] = todo()
+}
+
+fun testArrayAssignment3(n: Nothing) {
+    operator fun Nothing.set(i: Int, j: Int) {}
+    n[1] = 2
+}
+
+fun testArrayAssignment4(n: Nothing) {
+    operator fun Nothing.set(i: Int, a: Any) {}
+    n[1] = todo()
+}
+
+fun testArrayPlusAssign(array: Array<Any>) {
+    operator fun Any.plusAssign(a: Any) {}
+    array[1] += todo()
+}
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInAssignment.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInAssignment.fir.kt
new file mode 100644
index 00000000000..62e8cdabb94
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInAssignment.fir.kt
@@ -0,0 +1,18 @@
+fun testAssignment() {
+    var a = 1
+    a = todo()
+}
+
+fun testVariableDeclaration() {
+    val a = todo()
+}
+
+fun testPlusAssign() {
+    operator fun Int.plusAssign(i: Int) {}
+
+    var a = 1
+    a += todo()
+}
+
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInBinaryExpressions.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInBinaryExpressions.fir.kt
new file mode 100644
index 00000000000..16c3669ddcc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInBinaryExpressions.fir.kt
@@ -0,0 +1,39 @@
+fun testBinary1() {
+    operator fun Int.times(s: String) {}
+
+    todo() * ""
+}
+fun testBinary2() {
+    "1" + todo()
+}
+
+fun testElvis1() {
+    todo() ?: ""
+}
+
+fun testElvis2(s: String?) {
+    s ?: todo()
+
+    bar()
+}
+
+fun testAnd1(b: Boolean) {
+    b && todo()
+
+    bar()
+}
+
+fun testAnd2(b: Boolean) {
+    todo() && b
+}
+
+fun returnInBinary1(): Boolean {
+    (return true) && (return false)
+}
+
+fun returnInBinary2(): Boolean {
+    (return true) || (return false)
+}
+
+fun todo(): Nothing = throw Exception()
+fun bar() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInCalls.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInCalls.fir.kt
new file mode 100644
index 00000000000..3cbdbe4eb0e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInCalls.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun testArgumentInCall() {
+    fun bar(i: Int, s: String, x: Any) {}
+
+    bar(1, todo(), "")
+}
+
+fun testArgumentInVariableAsFunctionCall(f: (Any) -> Unit) {
+    f(todo())
+}
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInDeadCode.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInDeadCode.fir.kt
new file mode 100644
index 00000000000..f18f12bb79c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInDeadCode.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun unreachable0() {
+    return
+    return todo()
+}
+
+fun unreachable2() {
+    return
+    val a = todo()
+}
+
+fun unreachable3() {
+    return
+    bar(todo())
+}
+
+fun unreachable4(array: Array<Any>) {
+    return
+    array[todo()]
+}
+
+fun bar(a: Any) {}
+fun todo(): Nothing = throw Exception()
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInIf.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInIf.fir.kt
new file mode 100644
index 00000000000..bd22f23be28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInIf.fir.kt
@@ -0,0 +1,12 @@
+fun testIf() {
+    if (todo()) 1 else 2
+}
+
+fun testIf1(b: Boolean) {
+    if (b) todo() else 1
+
+    bar()
+}
+
+fun todo(): Nothing = throw Exception()
+fun bar() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInInnerExpressions.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInInnerExpressions.fir.kt
new file mode 100644
index 00000000000..6263d0d7291
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInInnerExpressions.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun testCompound() {
+    operator fun Nothing.get(i: Int) {}
+    todo()!![12]
+}
+
+fun testCompound1() {
+    operator fun Int.times(s: String): Array<String> = throw Exception()
+    (todo() * "")[1]
+}
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInLocalDeclarations.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInLocalDeclarations.fir.kt
new file mode 100644
index 00000000000..264569235d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInLocalDeclarations.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun testObject() {
+    object : Foo(todo()) {
+        fun foo() = 1
+    }
+}
+
+fun testObjectExpression() {
+    val a  = object : Foo(todo()) {
+        fun foo() = 1
+    }
+}
+
+fun testObjectExpression1() {
+    fun bar(i: Int, x: Any) {}
+
+    bar(1, object : Foo(todo()) {
+        fun foo() = 1
+    })
+}
+
+fun testClassDeclaration() {
+    class C : Foo(todo()) {}
+
+    bar()
+}
+
+fun testFunctionDefaultArgument() {
+    fun foo(x: Int = todo()) { bar() }
+}
+
+open class Foo(i: Int) {}
+
+fun todo(): Nothing = throw Exception()
+fun bar() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInLoops.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInLoops.fir.kt
new file mode 100644
index 00000000000..533b7798499
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInLoops.fir.kt
@@ -0,0 +1,21 @@
+fun testFor() {
+    operator fun Nothing.iterator() = (0..1).iterator()
+
+    for (i in todo()) {}
+}
+
+fun testWhile() {
+    while (todo()) {
+    }
+}
+
+fun testDoWhile() {
+    do {
+
+    } while(todo())
+
+    bar()
+}
+
+fun todo(): Nothing = throw Exception()
+fun bar() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInReturn.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInReturn.fir.kt
new file mode 100644
index 00000000000..704b1f3e7b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInReturn.fir.kt
@@ -0,0 +1,5 @@
+fun testReturn() {
+    return todo()
+}
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInUnaryExpr.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInUnaryExpr.fir.kt
new file mode 100644
index 00000000000..bd53f349b08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInUnaryExpr.fir.kt
@@ -0,0 +1,15 @@
+fun testPrefix() {
+    operator fun Any.not() {}
+    !todo()
+}
+
+fun testPostfixWithCall(n: Nothing) {
+    operator fun Nothing.inc(): Nothing = this
+    n++
+}
+
+fun testPostfixSpecial() {
+    todo()!!
+}
+
+fun todo(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInWhileFromBreak.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInWhileFromBreak.fir.kt
new file mode 100644
index 00000000000..8f2c49bd960
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/deadCodeInWhileFromBreak.fir.kt
@@ -0,0 +1,55 @@
+fun foo(a: Any) {}
+fun bar(a: Any, b: Any) {}
+
+fun test(arr: Array<Int>) {
+    while (true) {
+        foo(break)
+    }
+
+
+    while (true) {
+        bar(arr, break)
+    }
+
+    while (true) {
+        arr[break]
+    }
+
+    while (true) {
+        arr[1] = break
+    }
+
+    while (true) {
+        break
+        foo(1)
+    }
+
+    while (true) {
+        var x = 1
+        break
+        x = 2
+    }
+
+    while (true) {
+        var x = 1
+        x = break
+    }
+
+    // TODO: bug, should be fixed in CFA
+    while (true) {
+        if (1 > 2 && break && 2 > 3) {
+
+        }
+    }
+
+    // TODO: bug, should be fixed in CFA
+    while (true) {
+        if (1 > 2 || break || 2 > 3) {
+
+        }
+    }
+
+    while (true) {
+        break ?: null
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/expressionInUnitLiteral.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/expressionInUnitLiteral.fir.kt
new file mode 100644
index 00000000000..4270d560304
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/expressionInUnitLiteral.fir.kt
@@ -0,0 +1,8 @@
+fun main() {
+    "".run {
+        ""
+    }
+}
+
+
+fun <T> T.run(f: (T) -> Unit): Unit = f(this)
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_1.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_1.fir.kt
new file mode 100644
index 00000000000..e6f1e165083
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_1.fir.kt
@@ -0,0 +1,12 @@
+//KT-2585 Code in try-finally is incorrectly marked as unreachable
+
+fun foo(x: String): String {
+    try {
+        throw RuntimeException()
+    } finally {
+        try {
+        } catch (e: Exception) {
+        }
+        return x     // <- Wrong UNREACHABLE_CODE
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_2.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_2.fir.kt
new file mode 100644
index 00000000000..add01027427
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_2.fir.kt
@@ -0,0 +1,23 @@
+//KT-2585 Code in try-finally is incorrectly marked as unreachable
+
+fun foo() {
+    try {
+        throw RuntimeException()
+    } catch (e: Exception) {
+        return     // <- Wrong UNREACHABLE_CODE
+    } finally {
+        while (true);
+    }
+}
+
+fun bar() {
+    try {
+        throw RuntimeException()
+    } catch (e: Exception) {
+        return     // <- Wrong UNREACHABLE_CODE
+    } finally {
+        while (cond());
+    }
+}
+
+fun cond() = true
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_3.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_3.fir.kt
new file mode 100644
index 00000000000..f7bd9d8eb5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt2585_3.fir.kt
@@ -0,0 +1,9 @@
+//KT-2585 Code in try-finally is incorrectly marked as unreachable
+
+fun foo(x: String): String {
+    try {
+        throw RuntimeException() //should be marked as unreachable, but is not
+    } finally {
+        throw NullPointerException()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt3162tryAsInitializer.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt3162tryAsInitializer.fir.kt
new file mode 100644
index 00000000000..514476f04fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt3162tryAsInitializer.fir.kt
@@ -0,0 +1,12 @@
+//KT-3162 More precise try-finally error marking
+
+fun foo(x: String) : String {
+    val a = try {
+        x
+    } finally {
+        try {
+        } catch (e: Exception) {
+        }
+        return x
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt5200DeadCodeInLambdas.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt5200DeadCodeInLambdas.fir.kt
new file mode 100644
index 00000000000..9401436a8c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/kt5200DeadCodeInLambdas.fir.kt
@@ -0,0 +1,25 @@
+//KT-5200 Mark unreachable code in lambdas
+
+fun test1(): String {
+    doCall local@ {
+        throw NullPointerException()
+        "b3" //unmarked
+    }
+
+    return "OK"
+}
+
+fun test2(nonLocal: String, b: Boolean): String {
+    doCall local@ {
+        if (b) {
+            return@local "b1"
+        } else {
+            return@local "b2"
+        }
+        "b3" //unmarked
+    }
+
+    return nonLocal
+}
+
+inline fun doCall(block: ()-> String) = block()
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/returnInDeadLambda.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/returnInDeadLambda.fir.kt
new file mode 100644
index 00000000000..723ab38f1fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/deadCode/returnInDeadLambda.fir.kt
@@ -0,0 +1,11 @@
+
+inline fun myRun(b: () -> Unit) = b()
+
+fun foo() {
+    var a: Int
+    return
+
+    myRun {
+        return
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/ReturnFromFunctionInObject.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/ReturnFromFunctionInObject.fir.kt
new file mode 100644
index 00000000000..3673a7597d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/ReturnFromFunctionInObject.fir.kt
@@ -0,0 +1,13 @@
+interface X {
+    fun f(): Boolean
+}
+
+val m = object : X {
+    override fun f(): Boolean {
+    }
+
+    fun foo() {
+        fun local(): Int {
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/kt3444_ReturnFromLocalFunctions.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/kt3444_ReturnFromLocalFunctions.fir.kt
new file mode 100644
index 00000000000..29bcdda8fc7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/kt3444_ReturnFromLocalFunctions.fir.kt
@@ -0,0 +1,17 @@
+package f
+
+
+//KT-3444 Front-end doesn't check if local function or function of anonymous class returns value
+
+fun box(): Int {
+
+    fun local(): Int {
+    }
+
+    return local()
+}
+
+fun main() {
+    box()
+}
+
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/kt4034.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/kt4034.fir.kt
new file mode 100644
index 00000000000..40c2f3f5871
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/kt4034.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// KT-4034 An expression of type Nothing may not affect 'definite return' analysis
+
+interface JavaClassifierType
+interface TypeUsage
+interface JetType
+
+private fun transformClassifierType(classifierType: JavaClassifierType, howThisTypeIsUsed: TypeUsage): JetType? {
+    null!!
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/simpleClass.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/simpleClass.fir.kt
new file mode 100644
index 00000000000..74d1173e4b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturn/simpleClass.fir.kt
@@ -0,0 +1,19 @@
+// FILE: a.kt
+package test
+
+class A {}
+
+// FILE: b.kt
+package test.p; class C {fun f() {}}
+
+// FILE: c.kt
+package test.p; open class G<T> {open fun f(): T {} fun a() {}}
+
+// FILE: d.kt
+package test.p; class G2<E> : G<E> { fun g() : E {} override fun f() : E {}}
+
+// FILE: e.kt
+package test.p; fun foo() {}
+
+// FILE: f.kt
+package test.p; fun foo(a: C) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturnInWhen.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturnInWhen.fir.kt
new file mode 100644
index 00000000000..9a82f54ac4b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/definiteReturnInWhen.fir.kt
@@ -0,0 +1,6 @@
+fun illegalWhenBlock(a: Any): Int {
+    when(a) {
+        is Int -> return a
+        is String -> return a.length
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/delegatedPropertyEarlyAccess.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/delegatedPropertyEarlyAccess.fir.kt
new file mode 100644
index 00000000000..25ca351fb4f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/delegatedPropertyEarlyAccess.fir.kt
@@ -0,0 +1,32 @@
+// See also KT-10869: Accessing lazy properties from init causes IllegalArgumentException
+
+import kotlin.reflect.KProperty
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+}
+
+class Kaboom() {
+    // Here and below we should have errors for simple AND delegated
+    init {
+        delegated.hashCode()
+        simple.hashCode()
+        withGetter.hashCode()
+    }
+
+    val other = delegated
+
+    val another = simple
+
+    val something = withGetter
+    
+    val delegated: String by CustomDelegate()
+
+    val simple = "xyz"
+
+    val withGetter: String
+        get() = "abc"
+
+    // No error should be here
+    val after = delegated
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/doWhileAssignment.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/doWhileAssignment.fir.kt
new file mode 100644
index 00000000000..08fc5a5616d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/doWhileAssignment.fir.kt
@@ -0,0 +1,23 @@
+// See KT-15334: incorrect reassignment in do...while
+
+fun test() {
+    do {
+        val s: String
+        s = ""
+    } while (s == "")
+}
+
+fun test2() {
+    do {
+        val s: String
+        s = "1"
+        s = s + "2"
+    } while (s == "1")
+}
+
+fun test3() {
+    val s: String
+    do {
+        s = ""
+    } while (s != "")
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/doWhileNotDefined.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/doWhileNotDefined.fir.kt
new file mode 100644
index 00000000000..92c4f436540
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/doWhileNotDefined.fir.kt
@@ -0,0 +1,6 @@
+fun test(cond1: Boolean) {
+    do {
+        if (cond1) continue
+        val cond2 = false
+    } while (cond2) // cond2 may be not defined here
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/elvisNotProcessed.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/elvisNotProcessed.fir.kt
new file mode 100644
index 00000000000..3709119f6f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/elvisNotProcessed.fir.kt
@@ -0,0 +1,39 @@
+// !WITH_NEW_INFERENCE
+// See KT-8277
+// NI_EXPECTED_FILE
+
+val v = { true } ?: ( { true } ?:null!! )
+
+val w = if (true) {
+    { true }
+}
+else {
+    { true } ?: null!!
+}
+
+val ww = if (true) {
+    { true } ?: null!!
+}
+else if (true) {
+    { true } ?: null!!
+}
+else {
+    null!!
+}
+
+val n = null ?: (null ?: { true })
+
+fun l(): (() -> Boolean)? = null
+
+val b = null ?: ( l() ?: false)
+
+val bb = null ?: ( l() ?: null!!)
+
+val bbb = null ?: ( l() ?: null)
+
+val bbbb = ( l() ?: null) ?: ( l() ?: null)
+
+fun f(x : Long?): Long {
+    var a = x ?: (fun() {} ?: fun() {})
+    return a
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/enumCompanionInterdependence.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/enumCompanionInterdependence.fir.kt
new file mode 100644
index 00000000000..ef40ac1e577
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/enumCompanionInterdependence.fir.kt
@@ -0,0 +1,55 @@
+enum class B(val x: Int) {
+    B1(1),
+    B2(2);
+
+    companion object {
+        val SUM = B1.x + B2.x
+        val COPY = B1
+    }
+}
+
+enum class C(val x: Int) {
+    C1(SUM),
+    C2(1);
+
+    companion object {
+        val COPY = C2
+        val SUM = C1.x + COPY.x
+    }
+}
+
+// From KT-11769
+enum class Fruit(personal: Int) {
+    APPLE(1);
+
+    companion object {
+        val common = 20
+    }
+
+    val score = personal + common
+}
+
+// Another example from KT-11769
+enum class EnumCompanion1(val x: Int) {
+    INSTANCE(<!AMBIGUITY!>Companion<!>.<!UNRESOLVED_REFERENCE!>foo<!>()),
+    ANOTHER(foo());
+
+    companion object {
+        fun foo() = 42
+    }
+}
+// Also should be reported for implicit receiver
+enum class EnumCompanion2(val x: Int) {
+    INSTANCE(foo());
+
+    companion object {
+        fun foo() = 42
+    }
+}
+// But not for another enum
+enum class EnumCompanion3(val x: Int) {
+    INSTANCE(EnumCompanion1.foo()),
+    ANOTHER(EnumCompanion2.foo());
+
+    companion object
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/enumInterdependence.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/enumInterdependence.fir.kt
new file mode 100644
index 00000000000..8c282117050
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/enumInterdependence.fir.kt
@@ -0,0 +1,35 @@
+enum class A(val v: A) {
+    A1(A2),
+    A2(A1)
+}
+
+enum class D(val x: Int) {
+    D1(D2.x),
+    D2(D1.x)
+}
+
+enum class E(val v: Int) {
+    // KT-11769 related: there is no predictable initialization order for enum entry with non-companion object
+    E1(Nested.COPY);
+
+    object Nested {
+        val COPY = E1.v
+    }
+}
+// From KT-13322: cross reference should not be reported here
+object Object1 {
+    val y: Any = Object2.z
+    object Object2 {
+        val z: Any = Object1.y
+    }
+}
+
+// From KT-6054
+enum class MyEnum {
+    A, B;
+    val x = when(this) {
+        A -> 1
+        B -> 2
+        else -> 3
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/fieldAsClassDelegate.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/fieldAsClassDelegate.fir.kt
new file mode 100644
index 00000000000..7ee3c670c3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/fieldAsClassDelegate.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+// See KT-15566
+// NI_EXPECTED_FILE
+
+import DefaultHttpClient.client
+
+interface HttpClient
+
+class HttpClientImpl : HttpClient
+
+// Below we should have initialization error for both (!) delegates
+
+object DefaultHttpClient : HttpClient by client {
+    val client = HttpClientImpl()
+}
+
+object DefaultHttpClientWithGetter : HttpClient by client {
+    val client get() = HttpClientImpl()
+}
+
+object DefaultHttpClientWithFun : HttpClient by fClient() {
+}
+
+private fun fClient() = HttpClientImpl()
+
+private fun <T> lazy(init: () -> T): kotlin.Lazy<T> {
+    init()
+    null!!
+}
+
+object DefaultHttpClientWithBy : HttpClient by client {
+    val client by lazy { HttpClientImpl() }
+}
+
+object DefaultFqHttpClient : HttpClient by DefaultFqHttpClient.client {
+    val client = HttpClientImpl()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/infiniteLoops.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/infiniteLoops.fir.kt
new file mode 100644
index 00000000000..14d4aa846e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/infiniteLoops.fir.kt
@@ -0,0 +1,55 @@
+fun unreachable() {}
+
+fun a() {
+    do {
+    } while (true)
+    unreachable()
+}
+
+fun b() {
+    while (true) {
+    }
+    unreachable()
+}
+
+fun c() {
+    do {} while (1 == 1)
+}
+
+fun d() {
+    while (2 == 2) {}
+}
+
+fun use(arg: Any) = arg
+
+fun f(cond: Boolean) {
+    val bar: Any
+    do {
+        if (cond) {
+            bar = "value"
+            break
+        }
+    } while (true)
+    use(bar) // should work
+
+    val foo: Any
+    while (true) {
+        if (cond) {
+            foo = "value"
+            break
+        }
+    }
+    use(foo) // should work
+}
+
+fun g(): Int {
+    do {
+        if (true) return 12
+    } while (true)
+} // should work
+
+fun h(): Int {
+    while (true) {
+        if (true) return 12
+    }
+} // should work
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLambda.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLambda.fir.kt
new file mode 100644
index 00000000000..5af20bee534
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLambda.fir.kt
@@ -0,0 +1,77 @@
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+
+fun ignoreIt(f: () -> Unit) {}
+
+fun exec(f: () -> Unit) = f()
+
+fun foo() {
+    var x: Int
+    ignoreIt() {
+        // Ok
+        x = 42
+    }
+    // Error!
+    x.hashCode()
+}
+
+fun bar() {
+    val x: Int
+    exec {
+        x = 13
+    }
+}
+
+fun bar2() {
+    val x: Int
+    fun foo() {
+        x = 3
+    }
+    foo()
+}
+
+class My(val cond: Boolean) {
+
+    val y: Int
+
+    init {
+        val x: Int
+        if (cond) {
+            exec {
+
+            }
+            x = 1
+        }
+        else {
+            x = 2
+        }
+        y = x
+    }
+
+    constructor(): this(false) {
+        val x: Int
+        x = 2
+        exec {
+            x.hashCode()
+        }
+    }
+}
+
+class Your {
+    val y = if (true) {
+        val xx: Int
+        exec {
+            xx = 42
+        }
+        24
+    }
+    else 0
+}
+
+val z = if (true) {
+    val xx: Int
+    exec {
+        <!UNRESOLVED_REFERENCE!>xx<!> = 24
+    }
+    42
+}
+else 0
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalClass.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalClass.fir.kt
new file mode 100644
index 00000000000..95a87ad0c5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalClass.fir.kt
@@ -0,0 +1,90 @@
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+
+fun foo() {
+    var x: String
+    class A {
+        init {
+            x = ""
+        }
+    }
+    // Error! See KT-10042
+    x.length
+}
+
+fun bar() {
+    var x: String
+    object: Any() {
+        init {
+            x = ""
+        }
+    }
+    // Ok
+    x.length
+}
+
+fun gav() {
+    val x: String
+    class B {
+        init {
+            // Error! See KT-10445
+            x = ""
+        }
+    }
+    // Error! See KT-10042
+    x.length
+    val y: String
+    class C(val s: String) {
+        constructor(): this("") {
+            // Error!
+            y = s
+        }
+    }
+    y.length
+}
+
+open class Gau(val s: String)
+
+fun gau() {
+    val x: String
+    object: Any() {
+        init {
+            // Ok
+            x = ""
+        }
+    }
+    // Ok
+    x.length
+    val y: String
+    fun local() {
+        object: Any() {
+            init {
+                // Error!
+                y = ""
+            }
+        }
+    }
+    val z: String
+    object: Gau(if (true) {
+        z = ""
+        z
+    }
+    else "") {}
+}
+
+class My {
+    init {
+        val x: String
+        class Your {
+            init {
+                // Error! See KT-10445
+                x = ""
+            }
+        }
+    }
+}
+
+val top: Int
+
+fun init() {
+    top = 1
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalFun.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalFun.fir.kt
new file mode 100644
index 00000000000..7a73b9b2a62
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalFun.fir.kt
@@ -0,0 +1,8 @@
+fun foo() {
+    var x: Int
+    fun bar() {
+        x = 42
+    }
+    x.hashCode()
+    bar()
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalViaExplicitThis_after.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalViaExplicitThis_after.fir.kt
new file mode 100644
index 00000000000..6e7d54e92c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalViaExplicitThis_after.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +ReadDeserializedContracts +UseCallsInPlaceEffect
+// See KT-17479
+
+class Test {
+    val str: String
+    init {
+        run {
+            this@Test.str = "A"
+        }
+
+        run {
+            // Not sure do we need diagnostic also here
+            this@Test.str = "B"
+        }
+
+        str = "C"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalViaExplicitThis_before.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalViaExplicitThis_before.fir.kt
new file mode 100644
index 00000000000..b04ada52941
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalViaExplicitThis_before.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: -ReadDeserializedContracts -UseCallsInPlaceEffect
+// See KT-17479
+
+class Test {
+    val str: String
+    init {
+        run {
+            this@Test.str = "A"
+        }
+
+        run {
+            // Not sure do we need diagnostic also here
+            this@Test.str = "B"
+        }
+
+        str = "C"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1001.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1001.fir.kt
new file mode 100644
index 00000000000..a277ad97574
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1001.fir.kt
@@ -0,0 +1,34 @@
+//KT-1001 Argument 2 for @NotNull parameter of JetFlowInformationProvider.checkIsInitialized must not be null
+
+package kt1001
+
+fun foo(c: Array<Int>) {
+    return
+
+    for (i in c) {}
+    for (i in c) {}
+}
+
+//more tests
+
+fun t1() : Int {
+    try {
+        return 1
+    }
+    catch (e : Exception) {
+        return 2
+    }
+    return 3
+}
+
+fun t2() : Int {
+    try {
+        return 1
+    }
+    finally {
+        doSmth()
+    }
+    return 2
+}
+
+fun doSmth() {}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1027.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1027.fir.kt
new file mode 100644
index 00000000000..c1de5c360e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1027.fir.kt
@@ -0,0 +1,48 @@
+//KT-1027 Strange selection of unreachable code
+
+package kt1027
+
+fun foo(c: List<Int>) {
+    var i = 2
+
+    return
+
+    for (j in c) {  //strange selection of unreachable code
+        i += 23
+    }
+}
+
+fun t1() {
+    return
+
+    while(true) {
+        doSmth()
+    }
+}
+
+fun t2() {
+    return
+
+    do {
+        doSmth()
+    } while (true)
+}
+
+fun t3() {
+    return
+
+    try {
+        doSmth()
+    }
+    finally {
+        doSmth()
+    }
+}
+
+fun t4() {
+    return
+
+    (43)
+}
+
+fun doSmth() {}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1066.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1066.fir.kt
new file mode 100644
index 00000000000..60304fd2db5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1066.fir.kt
@@ -0,0 +1,34 @@
+//KT-1066 false 'Variable cannot be initialized before declaration'
+
+package kt1066
+
+fun randomDigit() = 0.toChar()
+
+fun foo(excluded: Set<Char>) {
+    var digit : Char
+
+    do {
+        digit = randomDigit()
+//      ^^^^^ here!
+    } while (excluded.contains(digit))
+}
+
+fun test() {
+    var sum : Int = 0
+    var first : Int = 1
+    var second : Int = 2
+    var temp : Int //= 0 // variable 'temp' initializer is redundant
+
+    while (true)
+    {
+        if (second > 4000000)
+            break
+
+        if (second % 2 == 0)
+            sum += second
+
+        temp = second
+        second = first + second
+        first = temp
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt10805.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt10805.fir.kt
new file mode 100644
index 00000000000..35863e4997f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt10805.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// AssertionError for nested ifs with lambdas and Nothing as results
+// NI_EXPECTED_FILE
+
+val fn = if (true) {
+    { true }
+} 
+else if (true) {
+    { true }
+}
+else {
+    null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt10823.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt10823.fir.kt
new file mode 100644
index 00000000000..14ffce99161
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt10823.fir.kt
@@ -0,0 +1,33 @@
+fun find2(): Any? {
+    fun visit(element: Any) {
+        return@find2 element
+    }
+    return null
+}
+
+// For find(): AssertionError at ControlFlowInstructionsGeneratorWorker.getExitPoint()
+
+fun find(): Any? {
+    object : Any() {
+        fun visit(element: Any) {
+            return@find element
+        }
+    }
+    return null
+}
+
+fun find4(): Any? {
+    inline fun visit(element: Any) {
+        return@find4 element
+    }
+    return null
+}
+
+fun find3(): Any? {
+    object : Any() {
+        inline fun visit(element: Any) {
+            return@find3 element
+        }
+    }
+    return null
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1156.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1156.fir.kt
new file mode 100644
index 00000000000..dc513f6d0fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1156.fir.kt
@@ -0,0 +1,7 @@
+//KT-1156 Throwing exception on the right side of elvis operator marks code unreachable
+
+
+fun foo(maybe: Int?) {
+    val i : Int = maybe ?: throw RuntimeException("No value")
+    System.out.println(i)
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1185enums.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1185enums.fir.kt
new file mode 100644
index 00000000000..80b24b11bdc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1185enums.fir.kt
@@ -0,0 +1,47 @@
+//KT-1185 Support full enumeration check for 'when'
+
+package kt1185
+
+enum class Direction {
+    NORTH,
+    SOUTH,
+    WEST,
+    EAST
+}
+
+class A {
+    companion object {
+
+    }
+}
+
+enum class Color(val rgb : Int) {
+    RED(0xFF0000),
+    GREEN(0x00FF00),
+    BLUE(0x0000FF)
+}
+
+fun foo(d: Direction) = when(d) { //no 'else' should be requested
+    Direction.NORTH -> 1
+    Direction.SOUTH -> 2
+    A -> 1
+    Direction.WEST -> 3
+    Direction.EAST -> 4
+}
+
+fun foo1(d: Direction) = when(d) {
+    Direction.NORTH -> 1
+    Direction.SOUTH -> 2
+    Direction.WEST -> 3
+}
+
+fun bar(c: Color) = when (c) {
+    Color.RED -> 1
+    Color.GREEN -> 2
+    Color.BLUE -> 3
+}
+
+fun bar1(c: Color) = when (c) {
+    Color.RED -> 1
+    Color.GREEN -> 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1189.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1189.fir.kt
new file mode 100644
index 00000000000..0039e5d4d04
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1189.fir.kt
@@ -0,0 +1,38 @@
+//KT-1189 StackOverflow in ide
+package kt1189
+import java.util.concurrent.locks.ReentrantReadWriteLock
+
+inline fun <T> ReentrantReadWriteLock.write(action: ()->T) : T {
+    val rl = readLock()
+    var readCount = 0
+    val writeCount = getWriteHoldCount()
+    if(writeCount == 0) {
+        readCount = getReadHoldCount()
+        if(readCount > 0)
+            for(i in 1..readCount)
+                rl.unlock()
+    }
+
+    val wl = writeLock()
+    wl.lock()
+    try {
+        return action()
+    }
+    finally {
+        if(readCount > 0) {
+            for(j in 1..readCount) {
+                rl.lock()
+            }
+        }
+        wl.unlock()
+    }
+}
+
+fun foo() {
+    try {
+        return
+    }
+    finally {
+        for (i in 1..10) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1191.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1191.fir.kt
new file mode 100644
index 00000000000..b4fef753131
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1191.fir.kt
@@ -0,0 +1,21 @@
+//KT-1191 Wrong detection of unused parameters
+package kt1191
+
+interface FunctionalList<T> {
+    val size: Int
+    val head: T
+    val tail: FunctionalList<T>
+}
+
+fun <T> FunctionalList<T>.plus(element: T) : FunctionalList<T> = object: FunctionalList<T> {
+    override val size: Int
+    get() = 1 + this@plus.size
+    override val tail: FunctionalList<T>
+    get() = this@plus
+    override val head: T
+    get() = element
+}
+
+fun foo(unused: Int) = object {
+    val a : Int get() = unused
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1219.1301.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1219.1301.fir.kt
new file mode 100644
index 00000000000..6e975f1d8f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1219.1301.fir.kt
@@ -0,0 +1,25 @@
+//KT-1219 Incorrect 'unused value' error in closures
+
+package kt1219
+
+fun <T, R> Iterable<T>.fold(a: R, op: (T, R) -> R) : R {
+    var r = a
+    this.foreach { r = op(it, r) } //unused value here
+    return r
+}
+
+//KT-1301 Modification of local of outer function in a local function should not be marked as unused assignment
+fun foo(){
+    var local = 0
+    fun bar(){
+        local = 1
+    }
+
+    bar()
+    System.out.println(local)
+}
+
+fun <T> Iterable<T>.foreach(operation: (element: T) -> Unit) {
+  for (elem in this)
+    operation(elem)
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1571.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1571.fir.kt
new file mode 100644
index 00000000000..399ca216f0d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1571.fir.kt
@@ -0,0 +1,42 @@
+//KT-1571 Frontend fails to check val reassigment for operator overloading.
+package kt1571
+
+var c0 = 0
+var c1 = 0
+var c2 = 0
+
+class A() {
+    var p = 0
+    operator fun divAssign(a : Int) {
+        c1++;
+    }
+    operator fun times(a : Int) : A {
+        c2++;
+        return this;
+    }
+}
+
+val a : A = A()
+get() {
+    c0++
+    return field
+}
+
+fun box() : String {
+
+    a /= 3
+    if (c0 != 1) {
+        return "1"
+    }
+    if (c1 != 1) {
+        return "2"
+    }
+    <!VARIABLE_EXPECTED!>a<!> *= 3 // a = a * 3, shouldn't be able to do this on val
+    if (c0 != 2) {
+        return "3"
+    }
+    if (c2 != 1) {
+        return "4"
+    }
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1977.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1977.fir.kt
new file mode 100644
index 00000000000..9cedcf94ddf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1977.fir.kt
@@ -0,0 +1,51 @@
+package kt1977
+
+//KT-1977 Wrong 'unused expression' in catch
+fun strToInt(s : String) : Int? =
+try {
+    Integer.parseInt(s)
+} catch(e : NumberFormatException) {
+    null
+}
+
+//more tests
+fun test1(s : String) : Int? {
+    return try {
+        88
+        Integer.parseInt(s)
+        22
+    }
+    catch (e: NumberFormatException) {
+        44
+    }
+    finally {
+        22
+    }
+}
+
+fun test2(s : String) : Int? {
+    return try {
+        88
+        Integer.parseInt(s)
+        22
+    } finally {
+            {
+            x : Int -> x
+            }
+    }
+}
+
+
+//KT-2015 False "Expression is unused" warnings
+fun foo() {
+    val i : Int = try{
+        bar()
+        1
+    }
+    catch(e : Exception){
+        0
+    }
+}
+
+fun bar() {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2166_kt2103.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2166_kt2103.fir.kt
new file mode 100644
index 00000000000..1fadd54bb53
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2166_kt2103.fir.kt
@@ -0,0 +1,17 @@
+package a
+
+//KT-2166 Control flow analysis doesn't detect that a 'while(true)' loop never terminates
+fun foo(): Int {
+    while (true) {
+    }
+}
+
+//KT-2103 Compiler requires return statement after loop which never exits
+fun foo1() : Boolean{
+    while(true){
+        if (bar()) continue
+        return true
+    }
+}
+
+fun bar() : Boolean = true
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2226.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2226.fir.kt
new file mode 100644
index 00000000000..f326ec0a926
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2226.fir.kt
@@ -0,0 +1,15 @@
+//KT-2226 Parameter used as delegation by object marked as unused
+package a
+
+interface A {
+    fun foo() : Int
+}
+
+class B : A {
+    override fun foo() = 10
+}
+fun foo(b: B) : Int {
+    val o = object : A by b {
+    }
+    return o.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2330.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2330.fir.kt
new file mode 100644
index 00000000000..8f5c98ebdf4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2330.fir.kt
@@ -0,0 +1,53 @@
+//KT-2330 Check visibility of getters and setters correspondingly
+package a
+
+class P {
+    var x : Int = 0
+        private set
+
+    var y : Int = 0
+
+    val other = P();
+
+    init {
+        x = 23
+        other.x = 4
+    }
+
+    val testInGetter : Int
+       get() {
+           x = 33
+           return 3
+       }
+}
+
+fun foo() {
+    val p = P()
+    p.x = 34 //should be an error here
+    p.y = 23
+
+    fun inner() {
+        p.x = 44
+    }
+}
+
+class R {
+    val p = P();
+    init {
+        p.x = 42
+    }
+
+    val testInGetterInOtherClass : Int
+        get() {
+            p.x = 33
+            return 3
+        }
+}
+
+fun test() {
+    val o = object {
+        fun run() {
+            <!UNRESOLVED_REFERENCE!>p<!>.<!UNRESOLVED_REFERENCE!>x<!> = 43
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2334.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2334.fir.kt
new file mode 100644
index 00000000000..8c1a5ae4aea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2334.fir.kt
@@ -0,0 +1,5 @@
+//KT-2334 An error 'local function without body' is not reported
+
+fun foo() {
+    fun bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2369.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2369.fir.kt
new file mode 100644
index 00000000000..1f464cc382f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2369.fir.kt
@@ -0,0 +1,13 @@
+//KT-2369 Variable is not marked as uninitialized in 'finally' section
+
+fun main() {
+    var x : Int
+    try {
+        throw Exception()
+    }
+    finally {
+        doSmth(x + 1)
+    }
+}
+
+fun doSmth(a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2845.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2845.fir.kt
new file mode 100644
index 00000000000..c77cd41a908
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2845.fir.kt
@@ -0,0 +1,18 @@
+//KT-2845 Wrong cf-analysys for variable initialization in try..finally
+package h
+
+import java.util.ArrayList
+
+private fun doTest() : Int {
+    var list : MutableList<Int>? ;
+    try {
+        list = ArrayList()
+        // Not-null was just assigned to the list
+        list.add(3)
+        return 0 ;
+    }
+    finally {
+        if(list != null) { // Must be an ERROR
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2960.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2960.fir.kt
new file mode 100644
index 00000000000..0058a90febb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2960.fir.kt
@@ -0,0 +1,36 @@
+//KT-2960 Perform control flow checks for package property initializers
+
+package b
+
+class P {
+    var x : Int = 0
+        private set
+}
+
+val p = P()
+var f = { -> p.x = 32 }
+
+val o = object {
+    fun run() {
+        p.x = 4
+
+        val z : Int
+        doSmth(z)
+    }
+}
+
+val g = { ->
+    val x: Int
+    doSmth(x)
+}
+
+class A {
+    val a : Int = 1
+      get() {
+          val x : Int
+          doSmth(x)
+          return field
+      }
+}
+
+fun doSmth(i: Int) = i
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2972.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2972.fir.kt
new file mode 100644
index 00000000000..2180b0912e5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt2972.fir.kt
@@ -0,0 +1,28 @@
+//KT-2972 Wrong "unused value" warning when finally is present
+
+import java.io.Closeable
+
+public inline fun <T: Closeable, R> T.use(block: (T)-> R) : R {
+    var closed = false
+    try {
+        return block(this)
+    } catch (e: Exception) {
+        closed = true // warning here
+        try {
+            this.close()
+        } catch (closeException: Exception) {
+            // eat the closeException as we are already throwing the original cause
+            // and we don't want to mask the real exception
+
+            // TODO on Java 7 we should call
+            // e.addSuppressed(closeException)
+            // to work like try-with-resources
+            // http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html#suppressed-exceptions
+        }
+        throw e
+    } finally {
+        if (!closed) {
+            this.close()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt3444.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt3444.fir.kt
new file mode 100644
index 00000000000..6cc325f83bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt3444.fir.kt
@@ -0,0 +1,13 @@
+fun box() {
+    fun local():Int {
+    }
+}
+
+interface X {
+    fun f(): Boolean
+}
+
+val m = object : X {
+    override fun f(): Boolean {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt3501.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt3501.fir.kt
new file mode 100644
index 00000000000..b65e04208d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt3501.fir.kt
@@ -0,0 +1,9 @@
+//KT-3501 Variable/parameter is highlighted as unused if it is used in member of local class
+
+fun f(p: String) { // "p" is marked as unused
+    class LocalClass {
+        fun f() {
+            p
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt4126.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt4126.fir.kt
new file mode 100644
index 00000000000..cebe74c945e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt4126.fir.kt
@@ -0,0 +1,3 @@
+public data class ProductGroup(val short_name: String, val parent: ProductGroup?) {
+    val name: String = if (parent == null) short_name else "${parent.name} $short_name"
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt4405.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt4405.fir.kt
new file mode 100644
index 00000000000..bdbd9ade546
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt4405.fir.kt
@@ -0,0 +1,30 @@
+//KT-4405 Control-flow analysis is not performed for some local declarations
+
+package d
+
+val closure = {
+    val x4 = "" // error: should be UNUSED_VARIABLE
+
+    fun g() {
+        val x6 = "" // error: should be UNUSED_VARIABLE
+    }
+
+    fun h(): Int { // error: should be NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY
+    }
+}
+
+class A {
+    init {
+        fun foo(): Int {
+        }
+
+        val closure = {
+            val x = ""
+
+            fun local(): Int {
+            }
+        }
+
+        val y = ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt510.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt510.fir.kt
new file mode 100644
index 00000000000..d9a7ecbfb9d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt510.fir.kt
@@ -0,0 +1,18 @@
+//KT-510 `this.` allows initialization without backing field
+
+package kt510
+
+public open class Identifier1() {
+    var field : Boolean
+    init {
+        field = false; // error
+    }
+}
+
+
+public open class Identifier2() {
+    var field : Boolean
+    init {
+        this.field = false;
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt607.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt607.fir.kt
new file mode 100644
index 00000000000..e3fe9a716c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt607.fir.kt
@@ -0,0 +1,18 @@
+//KT-607 Val reassignment is not marked as an error
+
+package kt607
+
+fun foo(a: A) {
+    val o = object {
+        val y : Int
+           get() = 42
+    }
+
+    a.z = 23
+    o.y = 11   //Should be an error here
+}
+
+class A() {
+    val z : Int
+    get() = 3
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt609.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt609.fir.kt
new file mode 100644
index 00000000000..42b529d62f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt609.fir.kt
@@ -0,0 +1,20 @@
+//KT-609 Analyze not only local variables, but function parameters as well in 'unused values' analysis
+
+package kt609
+
+fun test(a: Int) {
+    var aa = a
+    aa = 324 //should be an 'unused value' warning here
+}
+
+class C() {
+    fun foo(s: String) {}  //should be an 'unused variable' warning
+}
+
+open class A() {
+    open fun foo(s : String) {}  //should not be a warning
+}
+
+class B() : A() {
+    final override fun foo(s : String) {}  //should not be a warning
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt610.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt610.fir.kt
new file mode 100644
index 00000000000..7a6a2782ec3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt610.fir.kt
@@ -0,0 +1,10 @@
+//KT-610 Distinguish errors 'unused variable' and 'variable is assigned but never accessed'
+
+package kt610
+
+fun foo() {
+    var j = 9  //'unused variable' error
+
+    var i = 1  //should be an error 'variable i is assigned but never accessed'
+    i = 2
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt6788.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt6788.fir.kt
new file mode 100644
index 00000000000..82e506baf31
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt6788.fir.kt
@@ -0,0 +1,10 @@
+class A(val next: A? = null) {
+    val x: String
+    init {
+        next?.x = "a"
+    }
+}
+
+class B(val next: B? = null) {
+    var x: String = next?.x ?: "default" // it's ok to use `x` of next
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt776.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt776.fir.kt
new file mode 100644
index 00000000000..4095484537b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt776.fir.kt
@@ -0,0 +1,38 @@
+//KT-776 Wrong detection of unreachable code
+
+package kt776
+
+fun test5() : Int {
+    var x = 0
+    while(true) {
+        try {
+            if(x < 10) {
+                x++
+                continue
+            }
+            else {
+                break
+            }
+        }
+        finally {
+            x++
+        }
+    }
+    return x
+}
+
+fun test1() : Int {
+    try {
+        if (true) {
+            return 1
+        }
+        else {
+            return 2
+        }
+    }
+    finally {
+        doSmth()  //unreachable
+    }
+}
+
+fun doSmth() {}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt843.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt843.fir.kt
new file mode 100644
index 00000000000..8c5ba56b94f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt843.fir.kt
@@ -0,0 +1,8 @@
+//KT-843 Don't highlight incomplete variables as unused
+
+package kt843
+
+fun main() {
+    // Integer type
+    val<!SYNTAX!><!> // this word is grey, which looks strange
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt897.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt897.fir.kt
new file mode 100644
index 00000000000..2f74c87b7ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/kt897.fir.kt
@@ -0,0 +1,20 @@
+//KT-897 Don't allow assignment to a property before it is defined
+
+package kt897
+
+class A() {
+    init {
+        i = 11
+    }
+    val i : Int? = null // must be an error
+
+    init {
+        j = 1
+    }
+    var j : Int = 2
+
+    init {
+        k = 3
+    }
+    val k : Int
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/localClasses.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/localClasses.fir.kt
new file mode 100644
index 00000000000..775de2d3bb3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/localClasses.fir.kt
@@ -0,0 +1,26 @@
+package f
+
+fun f() {
+    class LocalClass() {
+        init {
+            val x1 = "" // ok: unused
+
+            fun loc1(): Int {
+                val x1_ = "" // ok: unused
+            }
+        }
+
+        fun f() {
+            val x2 = "" // error: should be UNUSED_VARIABLE
+
+            fun loc2(): Int {
+                val x2_ = "" // error: should be UNUSED_VARIABLE
+            }
+        }
+
+        val v: String
+            get() {
+                val x3 = "" // ok: unused
+            }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/localObjectInConstructor.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/localObjectInConstructor.fir.kt
new file mode 100644
index 00000000000..3cb2bd13754
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/localObjectInConstructor.fir.kt
@@ -0,0 +1,87 @@
+fun println(obj: Any?) = obj
+
+class Demo0 {
+    private val some = object {
+        fun foo() {
+            println(state)
+        }
+    }
+
+    private var state: Boolean = true
+}
+
+class Demo1 {
+    private val some = object {
+        fun foo() {
+            if (state)
+                state = true
+
+            println(state)
+        }
+    }
+
+    private var state: Boolean = true
+}
+
+class Demo1A {
+    fun foo() {
+        if (state)
+            state = true
+
+        println(state)
+    }
+
+    private var state: Boolean = true
+}
+
+class Demo2 {
+    private val some = object {
+        fun foo() {
+            if (state)
+                state = true
+            else
+                state = false
+
+            println(state)
+        }
+    }
+
+    private var state: Boolean = true
+}
+
+class Demo3 {
+    private val some = run {
+        if (state)
+            state = true
+
+        println(state)
+    }
+
+    private var state: Boolean = true
+}
+
+fun <T> exec(f: () -> T): T = f()
+
+class Demo4 {
+    private val some = exec {
+        if (state)
+            state = true
+
+        println(state)
+    }
+
+    private var state: Boolean = true
+}
+
+class Demo5 {
+    private var state: Boolean = true
+
+    private val some = object {
+        fun foo() {
+            if (state)
+                state = true
+
+            println(state)
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/mainWithWarningOnUnusedParam.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/mainWithWarningOnUnusedParam.fir.kt
new file mode 100644
index 00000000000..647da0962c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/mainWithWarningOnUnusedParam.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: +WarningOnMainUnusedParameter
+
+fun main(args: Array<String>) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/mainWithoutWarningOnUnusedParam.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/mainWithoutWarningOnUnusedParam.fir.kt
new file mode 100644
index 00000000000..9ed477daa2e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/mainWithoutWarningOnUnusedParam.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: -WarningOnMainUnusedParameter
+
+fun main(args: Array<String>) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/nestedTryFinally.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/nestedTryFinally.fir.kt
new file mode 100644
index 00000000000..eb493096c80
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/nestedTryFinally.fir.kt
@@ -0,0 +1,24 @@
+fun use(arg: String?) = arg
+
+fun sample(): String? {
+    try {
+        if (false) {
+            return "fail"
+        } else {
+            if (false) {
+                if (false) {
+                    var foo: String? = null
+                    try {
+                        foo = "test"
+                    } catch (e: Exception) {
+                        return "fail"
+                    } finally {
+                        use(foo) // 'foo' is initialized here
+                    }
+                }
+                return "fail"
+            }
+        }
+    } finally {}
+    return null
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/nonLocalReturnUnreachable.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/nonLocalReturnUnreachable.fir.kt
new file mode 100644
index 00000000000..f09cc4b1f50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/nonLocalReturnUnreachable.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// See also KT-5198 / KT-10186
+
+inline fun doCall(f: () -> Unit) = f()
+
+fun test1(nonLocal: String): String {
+    val localResult = doCall {
+        return nonLocal  //unreachable
+    }
+    return "NON_LOCAL_FAILED $localResult"  //unreachable
+}
+
+fun doSomething() {}
+
+fun test2() {
+    fun f(x: Any?) = x
+    f(null?.let { return })
+
+    // false unreachable here
+    doSomething()
+}
+
+fun test3(x: Any?): Boolean =
+    x?.let {
+        return true
+    } ?: false
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/nonLocalReturnWithFinally.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/nonLocalReturnWithFinally.fir.kt
new file mode 100644
index 00000000000..37c23610960
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/nonLocalReturnWithFinally.fir.kt
@@ -0,0 +1,10 @@
+fun test(name: String?) {
+    try {
+        name?.let {
+            return
+        }
+    }
+    finally {
+        name?.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/privateSetter.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/privateSetter.fir.kt
new file mode 100644
index 00000000000..87364ae72a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/privateSetter.fir.kt
@@ -0,0 +1,17 @@
+open class X(s : String) {
+    public var n: String = s
+        private set
+
+}
+
+class Z : X("subclass") {
+    fun print(): String {
+        n = n
+        return n;
+    }
+}
+
+
+fun box() : String {
+    return Z().print() //error
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstance.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstance.fir.kt
new file mode 100644
index 00000000000..71ec7c200e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstance.fir.kt
@@ -0,0 +1,12 @@
+class A(val next: A? = null) {
+    val x: String
+    init {
+        next?.x = "a"
+        x = "b"
+        this.x = "c"
+        x = "d" // don't repeat the same diagnostic again with this receiver
+        this.x = "e"
+
+        next?.x = "f"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstanceInner.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstanceInner.fir.kt
new file mode 100644
index 00000000000..38e9e36656d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstanceInner.fir.kt
@@ -0,0 +1,21 @@
+class Outer {
+    val outerProp: String
+    inner class Inner(inner: Inner, outer: Outer) {
+        val innerProp: String
+        init {
+            outerProp // use of outerProp is ok because we're suppose that Outer instance should be initialized
+            this@Outer.outerProp
+
+            this@Outer.outerProp = "1"
+            outerProp = "2" // do not repeat the same diagnostic with this receiver of outer class
+            outer.outerProp = "3"
+
+            innerProp = "4" + inner.innerProp
+            this@Inner.innerProp = "5"
+            innerProp = "6" // do not repeat the same diagnostic with this receiver
+            this@Inner.innerProp = "7"
+
+            inner.innerProp = "8"
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstanceThisLabel.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstanceThisLabel.fir.kt
new file mode 100644
index 00000000000..ed28c8edac7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesInitWithOtherInstanceThisLabel.fir.kt
@@ -0,0 +1,12 @@
+class A(val next: A? = null) {
+    val x: String
+    init {
+        next?.x = "a"
+        this@A.x = "b"
+        this.x = "c"
+        x = "d" // don't repeat the same diagnostic again with this receiver
+        this@A.x = "e"
+
+        next?.x = "f"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesOrderInPackage.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesOrderInPackage.fir.kt
new file mode 100644
index 00000000000..2ca95e2a6a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/propertiesOrderInPackage.fir.kt
@@ -0,0 +1,4 @@
+package a
+
+val a : Int = b
+val b : Int = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/reassignmentInTryCatch.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/reassignmentInTryCatch.fir.kt
new file mode 100644
index 00000000000..f13951b8340
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/reassignmentInTryCatch.fir.kt
@@ -0,0 +1,102 @@
+// KT-13612 related tests (reassignment in try-catch-finally)
+
+fun f1() {
+    val n: Int
+    try {
+        n = 1
+        throw Exception()
+    }
+    catch (e: Exception) {
+        // KT-13612: reassignment
+        n = 2
+    }
+    n.hashCode()
+}
+
+fun f2() {
+    val n: Int
+    try {
+        n = 1
+        throw Exception()
+    }
+    finally {
+        n = 2
+    }
+    n.hashCode()
+}
+
+fun g1(flag: Boolean) {
+    val n: Int
+    try {
+        if (flag) throw Exception()
+        n = 1
+    }
+    catch (e: Exception) {
+        // KT-13612: ? reassignment or definite assignment ?
+        n = 2
+    }
+    n.hashCode()
+}
+
+fun g2(flag: Boolean) {
+    val n: Int
+    try {
+        if (flag) throw Exception()
+        n = 1
+    }
+    finally {
+        n = 2
+    }
+    n.hashCode()
+}
+
+fun h1(flag: Boolean) {
+    val n = try {
+        if (flag) throw Exception()
+        1
+    }
+    catch (e: Exception) {
+        2
+    }
+    n.hashCode()
+}
+
+fun h2(flag: Boolean) {
+    val n = try {
+        if (flag) throw Exception()
+        1
+    }
+    finally {
+        2
+    }
+    n.hashCode()
+}
+
+fun j(flag: Boolean) {
+    if (flag) throw Exception()
+}
+
+fun k1(flag: Boolean) {
+    val n: Int
+    try {
+        n = 1
+        j(flag)
+    }
+    catch (e: Exception) {
+        // KT-13612: reassignment
+        n = 2
+    }
+    n.hashCode()
+}
+
+fun k2(flag: Boolean) {
+    val n: Int
+    try {
+        n = 1
+        j(flag)
+    }
+    finally {
+        n = 2
+    }
+    n.hashCode()
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/reassignmentInTryCatchWithJumps.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/reassignmentInTryCatchWithJumps.fir.kt
new file mode 100644
index 00000000000..ea546d9889d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/reassignmentInTryCatchWithJumps.fir.kt
@@ -0,0 +1,55 @@
+fun exc(flag: Boolean) {
+    if (flag) throw Exception()
+}
+
+fun f1(flag: Boolean) {
+    val n: Int
+    try {
+        if (flag) {
+            n = 1
+            exc(flag)
+            return
+        }
+    }
+    catch (e: Exception) {
+        // KT-13612: reassignment
+        n = 3
+    }
+    n.hashCode()
+}
+
+fun f2(flag: Boolean) {
+    while (true) {
+        val n: Int
+        try {
+            if (flag) {
+                n = 1
+                exc(flag)
+                break
+            }
+        }
+        catch (e: Exception) {
+            // KT-13612: reassignment
+            n = 3
+        }
+        n.hashCode()
+    }
+}
+
+fun f3(flag: Boolean) {
+    while (true) {
+        val n: Int
+        try {
+            if (flag) {
+                n = 1
+                exc(flag)
+                continue
+            }
+        }
+        catch (e: Exception) {
+            // KT-13612: reassignment
+            n = 3
+        }
+        n.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/referenceToPropertyInitializer.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/referenceToPropertyInitializer.fir.kt
new file mode 100644
index 00000000000..293091f3571
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/referenceToPropertyInitializer.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+package o
+
+class TestFunctionLiteral {
+    val sum: (Int) -> Int = { x: Int ->
+        sum(x - 1) + x
+    }
+    val foo: () -> Unit = l@ ({ foo() })
+}
+
+open class A(val a: A)
+
+class TestObjectLiteral {
+    val obj: A = object: A(obj) {
+        init {
+            val x = obj
+        }
+        fun foo() {
+            val y = obj
+        }
+    }
+    val obj1: A = l@ ( object: A(obj1) {
+        init {
+            val x = obj1
+        }
+        fun foo() = obj1
+    })
+}
+
+class TestOther {
+    val x: Int = x + 1
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/repeatUnitializedErrorOnlyForLocalVars.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/repeatUnitializedErrorOnlyForLocalVars.fir.kt
new file mode 100644
index 00000000000..0f944cb0c97
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/repeatUnitializedErrorOnlyForLocalVars.fir.kt
@@ -0,0 +1,15 @@
+package aa
+
+val a : Int = b
+val b : Int = a + b
+
+class C {
+    val a : Int = b
+    val b : Int = a + b
+}
+
+fun foo() {
+    val a : Int
+    a + 1
+    a + 1
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/scopeOfAnonymousInitializer.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/scopeOfAnonymousInitializer.fir.kt
new file mode 100644
index 00000000000..6958b958954
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/scopeOfAnonymousInitializer.fir.kt
@@ -0,0 +1,5 @@
+class AnonymousInitializers(var a: String) {
+    init {
+        a = "s"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/throwInLambda.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/throwInLambda.fir.kt
new file mode 100644
index 00000000000..40108a81c53
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/throwInLambda.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// See KT-10913 Bogus unreachable code warning
+
+fun fn() : String? = null
+fun foo(): String {
+    val x = fn()?.let { throw Exception() } ?: "unreachable?"
+    return x
+}
+fun bar(): String {
+    val x = fn() ?: return ""
+    val y = x?.let { throw Exception() } ?: "unreachable"
+    return y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/tryWithAssignmentUsedInCatch.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/tryWithAssignmentUsedInCatch.fir.kt
new file mode 100644
index 00000000000..953ca2944d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/tryWithAssignmentUsedInCatch.fir.kt
@@ -0,0 +1,36 @@
+fun f() {
+    var foo = 1
+    try {
+        foo = 2
+        throw RuntimeException()
+    } catch (e: Throwable) {
+        foo.hashCode()
+    }
+    throw Exception()
+}
+
+fun g() {
+    var foo = 1
+    try {
+        foo = 2
+        f()
+    } catch (e: Throwable) {
+        foo.hashCode()
+    }
+}
+
+fun h() {
+    try {
+
+    }
+    finally {
+        var foo = 1
+        try {
+            foo = 2
+            g()
+        }
+        catch (e: Throwable) {
+            foo.hashCode()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/uninitializedInLocalDeclarations.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/uninitializedInLocalDeclarations.fir.kt
new file mode 100644
index 00000000000..7182fbeede5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/uninitializedInLocalDeclarations.fir.kt
@@ -0,0 +1,50 @@
+fun test1() {
+    fun bar() {
+        var i : Int
+        doSmth(i)
+    }
+}
+
+fun test2() {
+    fun foo() {
+        val s: String?
+
+        try {
+            s = ""
+        }
+        catch(e: Exception) {
+            doSmth(e)
+        }
+
+        doSmth(s)
+    }
+}
+
+fun test3() {
+    val f = {
+        val a : Int
+        doSmth(a)
+    }
+}
+
+fun test4() {
+    doSmth {
+        val a : Int
+        doSmth(a)
+    }
+}
+
+fun test5() {
+    fun inner1() {
+        fun inner2() {
+            fun inner3() {
+                fun inner4() {
+                    val a : Int
+                    doSmth(a)
+                }
+            }
+        }
+    }
+}
+
+fun doSmth(a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unmappedArgs.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unmappedArgs.fir.kt
new file mode 100644
index 00000000000..0e41d12110d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unmappedArgs.fir.kt
@@ -0,0 +1,5 @@
+fun foo(a: Int, b: Int) = a + b
+
+fun bar(i: Int) {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, 1, i)
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitRecursiveInLambda.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitRecursiveInLambda.fir.kt
new file mode 100644
index 00000000000..718684da9b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitRecursiveInLambda.fir.kt
@@ -0,0 +1,6 @@
+class Test {
+    lateinit var someRunnable: Runnable
+    init {
+        someRunnable = Runnable { someRunnable.run() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithConstructor.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithConstructor.fir.kt
new file mode 100644
index 00000000000..7a57d63a6f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithConstructor.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    lateinit var bar: String
+
+    constructor(baz: Int) {
+        bar = ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithErroneousDelegation.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithErroneousDelegation.fir.kt
new file mode 100644
index 00000000000..b76c4504f2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithErroneousDelegation.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    lateinit var x: String
+
+    constructor() {
+        x = "Foo"
+    }
+
+    constructor(x: String, y: String): <!INAPPLICABLE_CANDIDATE!>this<!>(y.hashCode())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithInit.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithInit.fir.kt
new file mode 100644
index 00000000000..04830ba3d15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithInit.fir.kt
@@ -0,0 +1,7 @@
+class Foo {
+    lateinit var bar: String
+
+    init {
+        bar = ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructors.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructors.fir.kt
new file mode 100644
index 00000000000..fd270a5b94a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructors.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    lateinit var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(baz: Int) {
+        bar = ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructorsAndDelegation.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructorsAndDelegation.fir.kt
new file mode 100644
index 00000000000..34ab09baf8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithMultipleConstructorsAndDelegation.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    lateinit var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(a: Int) : this() {
+    }
+
+    constructor(a: Int, b: Int) : this(a) {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPlusAssign.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPlusAssign.fir.kt
new file mode 100644
index 00000000000..332526497b9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPlusAssign.fir.kt
@@ -0,0 +1,8 @@
+class Foo {
+    lateinit var bar: String
+
+    constructor(baz: Int) {
+        // At best, we should have error here despite of lateinit
+        bar += baz
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPrimaryConstructorAndConstructor.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPrimaryConstructorAndConstructor.fir.kt
new file mode 100644
index 00000000000..d1d946dbf1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/lateinitWithPrimaryConstructorAndConstructor.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo() {
+    lateinit var bar: String
+
+    constructor(baz: Int) : this() {
+        bar = ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinit.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinit.fir.kt
new file mode 100644
index 00000000000..abee30f6f36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinit.fir.kt
@@ -0,0 +1,7 @@
+class Foo {
+    lateinit var bar: String
+
+    fun init() {
+        bar = ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinitWithTwoConstructors.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinitWithTwoConstructors.fir.kt
new file mode 100644
index 00000000000..2c54f35a1f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/normalLateinitWithTwoConstructors.fir.kt
@@ -0,0 +1,9 @@
+class Foo {
+    lateinit var x: String
+
+    constructor(y: String) {
+        x = y
+    }
+
+    constructor()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateItself.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateItself.fir.kt
new file mode 100644
index 00000000000..510b7e292f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateItself.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    lateinit var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(a: Int) : this(a) {
+        bar = "a"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateLoop.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateLoop.fir.kt
new file mode 100644
index 00000000000..596b60c7c99
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unnecessaryLateinit/secondaryConstructorDelegateLoop.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    lateinit var bar: String
+
+    constructor() {
+        bar = ""
+    }
+
+    constructor(a: Int) : this(a, 0, 0) {
+    }
+
+    constructor(a: Int, b: Int) : this(a) {
+    }
+
+    constructor(a: Int, b: Int, c: Int) : this(a, b) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unresolvedReference.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unresolvedReference.fir.kt
new file mode 100644
index 00000000000..f8e4734ccb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unresolvedReference.fir.kt
@@ -0,0 +1,49 @@
+// See KT-6665: unresolved reference (v.bar) should not produce "unreachable code" after it
+
+fun foo(): Int {
+    val v = 1
+    val c = v.<!UNRESOLVED_REFERENCE!>bar<!> ?: return 0
+    return 42
+}
+
+fun foo2(): Int {
+    val v = 1
+    val c = if (true) v.<!UNRESOLVED_REFERENCE!>bar<!> else return 3
+    val b = c
+    return 42
+}
+
+fun foo3(): Int {
+    val v = 1
+    val c = when {
+        true -> v.<!UNRESOLVED_REFERENCE!>bar<!>
+        else -> return 3
+    }
+    val b = c
+    return 42
+}
+
+// Type + ErrorType should give Type, unless Type is Nothing
+
+fun bar(): Int {
+    val v = 1
+    val c = v.<!UNRESOLVED_REFERENCE!>bar<!> ?: 42
+    return c
+}
+
+fun bar2(): Int {
+    val v = 1
+    val c = if (true) v.<!UNRESOLVED_REFERENCE!>bar<!> else 3
+    val b = c
+    return b
+}
+
+fun bar3(): Int {
+    val v = 1
+    val c = when {
+        true -> v.<!UNRESOLVED_REFERENCE!>bar<!>
+        else -> 3
+    }
+    val b = c
+    return b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/unusedInAnonymous.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unusedInAnonymous.fir.kt
new file mode 100644
index 00000000000..7495cd3595d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/unusedInAnonymous.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: -SingleUnderscoreForParameterName
+// See KT-8813, KT-9631
+
+fun someApi(f: (Int) -> Unit) = f(42)
+
+fun test() {
+    someApi(fun(p: Int) {})
+    // Apparently "p" cannot be removed because the signature is fixed by "someApi
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/useUninitializedInLambda.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/useUninitializedInLambda.fir.kt
new file mode 100644
index 00000000000..9c6fef2ec46
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/useUninitializedInLambda.fir.kt
@@ -0,0 +1,6 @@
+fun bar(f: () -> Unit) = f()
+
+fun foo() {
+    var v: Any
+    bar { v.hashCode() }
+}
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/varInitializationInIfInCycle.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/varInitializationInIfInCycle.fir.kt
new file mode 100644
index 00000000000..5757b44bd08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/varInitializationInIfInCycle.fir.kt
@@ -0,0 +1,15 @@
+fun foo(numbers: Collection<Int>) {
+    for (i in numbers) {
+        val b: Boolean
+        if (1 < 2) {
+            b = false
+        }
+        else {
+            b = true
+        }
+        use(b)
+        continue
+    }
+}
+
+fun use(vararg a: Any?) = a
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ForLoopWithExtensionIteratorOnNullable.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ForLoopWithExtensionIteratorOnNullable.fir.kt
new file mode 100644
index 00000000000..b7ff32fb78a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ForLoopWithExtensionIteratorOnNullable.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// See also KT-7428
+class Container<K>(val k: K)
+// iterator() must be an extension, otherwise code will not compile
+operator fun <K> Container<K>.iterator(): Iterator<K> = null!!
+
+fun test() {
+    val container: Container<String>? = null
+    // Error
+    container.<!INAPPLICABLE_CANDIDATE!>iterator<!>()
+    // for extension iterator, this code compiles, but should not
+    <!INAPPLICABLE_CANDIDATE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (s in container) {}<!>
+}
+class OtherContainer<K>(val k: K) {
+    operator fun iterator(): Iterator<K> = null!!
+}
+
+fun test2() {
+    val other: OtherContainer<String>? = null
+    // Error
+    <!INAPPLICABLE_CANDIDATE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (s in other) {}<!>
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ForWithoutBraces.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ForWithoutBraces.fir.kt
new file mode 100644
index 00000000000..d79dd7e77e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ForWithoutBraces.fir.kt
@@ -0,0 +1,8 @@
+// http://youtrack.jetbrains.net/issue/KT-552
+// KT-552 For variable unresolved if loop body is not block
+
+fun ff() {
+    var i = 1
+    for (j in 1..10)
+        i += j
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ForbidStatementAsDirectFunctionBody.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ForbidStatementAsDirectFunctionBody.fir.kt
new file mode 100644
index 00000000000..764126042c6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ForbidStatementAsDirectFunctionBody.fir.kt
@@ -0,0 +1,11 @@
+
+fun foo1() = <!INFERENCE_ERROR, INFERENCE_ERROR, INFERENCE_ERROR!>while (b()) {}<!>
+
+fun foo2() = <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (i in 10) {}<!>
+
+fun foo3() = when (b()) {
+    true -> 1
+    else -> 0
+}
+
+fun b(): Boolean = true
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/catchGenerics.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/catchGenerics.fir.kt
new file mode 100644
index 00000000000..44d55d0b17a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/catchGenerics.fir.kt
@@ -0,0 +1,26 @@
+// JAVAC_EXPECTED_FILE
+// See KT-9816, KT-9742
+
+// Not allowed in Java
+class ZException<T>(val p: T) : Exception()
+
+class YException<T>(val p: T): java.lang.RuntimeException()
+
+class XException<T>(val p: T): Throwable()
+
+fun bar() {
+    try {
+        throw ZException(11)
+    } catch (e: ZException<*>) {}    
+}
+
+inline fun <reified E : Exception, R> tryCatch(lazy: () -> R, failure: (E) -> R): R =
+    try {
+        lazy()
+    } catch (e: E) {
+        failure(e)
+    }
+
+fun <T : Throwable> tryCatch() {
+    try { } catch (e: T) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/catchInnerClassesOfGenerics.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/catchInnerClassesOfGenerics.fir.kt
new file mode 100644
index 00000000000..7f3299674df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/catchInnerClassesOfGenerics.fir.kt
@@ -0,0 +1,41 @@
+// !LANGUAGE: +ProhibitInnerClassesOfGenericClassExtendingThrowable
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// JAVAC_EXPECTED_FILE
+
+class OuterGeneric<T> {
+    inner class ErrorInnerExn : Exception()
+
+    inner class InnerA {
+        inner class ErrorInnerExn2 : Exception()
+    }
+
+    class OkNestedExn : Exception()
+
+    val errorAnonymousObjectExn = object : Exception() {}
+
+    fun foo() {
+        class OkLocalExn : Exception()
+
+        val errorAnonymousObjectExn = object : Exception() {}
+    }
+
+    fun <X> genericFoo() {
+        class OkLocalExn : Exception()
+
+        class LocalGeneric<Y> {
+            inner class ErrorInnerExnOfLocalGeneric : Exception()
+        }
+    }
+}
+
+class Outer {
+    inner class InnerGeneric<T> {
+        inner class ErrorInnerExn : Exception()
+    }
+}
+
+fun <T> genericFoo() {
+    class ErrorLocalExnInGenericFun : Exception()
+
+    val errorkAnonymousObjectExnInGenericFun = object : Exception() {}
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/catchInnerClassesOfGenerics_deprecation.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/catchInnerClassesOfGenerics_deprecation.fir.kt
new file mode 100644
index 00000000000..cbe8d725b61
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/catchInnerClassesOfGenerics_deprecation.fir.kt
@@ -0,0 +1,41 @@
+// !LANGUAGE: -ProhibitInnerClassesOfGenericClassExtendingThrowable
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// JAVAC_EXPECTED_FILE
+
+class OuterGeneric<T> {
+    inner class ErrorInnerExn : Exception()
+
+    inner class InnerA {
+        inner class ErrorInnerExn2 : Exception()
+    }
+
+    class OkNestedExn : Exception()
+
+    val errorAnonymousObjectExn = object : Exception() {}
+
+    fun foo() {
+        class OkLocalExn : Exception()
+
+        val errorAnonymousObjectExn = object : Exception() {}
+    }
+
+    fun <X> genericFoo() {
+        class OkLocalExn : Exception()
+
+        class LocalGeneric<Y> {
+            inner class ErrorInnerExnOfLocalGeneric : Exception()
+        }
+    }
+}
+
+class Outer {
+    inner class InnerGeneric<T> {
+        inner class ErrorInnerExn : Exception()
+    }
+}
+
+fun <T> genericFoo() {
+    class ErrorLocalExnInGenericFun : Exception()
+
+    val errorkAnonymousObjectExnInGenericFun = object : Exception() {}
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/catchWithDefault.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/catchWithDefault.fir.kt
new file mode 100644
index 00000000000..8e568f28604
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/catchWithDefault.fir.kt
@@ -0,0 +1,3 @@
+fun test() {
+    try { } catch (e: Exception = Exception()) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/catchingLocalClassesCapturingTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/catchingLocalClassesCapturingTypeParameters.fir.kt
new file mode 100644
index 00000000000..39925d38fef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/catchingLocalClassesCapturingTypeParameters.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +ProhibitInnerClassesOfGenericClassExtendingThrowable
+package test
+
+var global: Throwable? = null
+
+fun <T> foo(x: Throwable, z: T, b: (T) -> Unit) {
+    class A(val y : T) : Exception()
+
+    try {
+        throw x
+    } catch (a: A) {
+        b(a.y)
+    } catch (e: Throwable) {
+        global = A(z)
+    }
+}
+
+fun main() {
+    foo(RuntimeException(), 1) { throw IllegalStateException() }
+    foo(global!!, "") { it.length } // (*)
+}
+
+// (*):
+//Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
+//  at test.TestKt$main$2.invoke(test.kt)
+//  at test.TestKt.foo(test.kt:12)
+//  at test.TestKt.main(test.kt:21)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/commonSupertypeOfT.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/commonSupertypeOfT.fir.kt
new file mode 100644
index 00000000000..b6c4f6021ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/commonSupertypeOfT.fir.kt
@@ -0,0 +1,30 @@
+// KT-6774 Cannot find equals() when comparing with null
+
+fun <T: Any> fn(t1: T, t2: T?) {
+    val x = if (true) t1 else t2
+    x == null
+    x?.equals(null)
+    x?.hashCode()
+    x.toString()
+    x!!.hashCode()
+
+    val y = t2 ?: t1
+    y == t1
+    y.equals(null)
+    y.hashCode()
+    y.toString()
+    y.hashCode()
+}
+
+interface Tr {
+    fun foo()
+}
+
+fun <T: Tr> fn(t1: T, t2: T?) {
+    val x = if (true) t1 else t2
+    x?.foo()
+    x!!.foo()
+
+    val y = t2 ?: t1
+    y.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/continueAndBreakLabelWithSameFunctionName.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/continueAndBreakLabelWithSameFunctionName.fir.kt
new file mode 100644
index 00000000000..626811aacc7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/continueAndBreakLabelWithSameFunctionName.fir.kt
@@ -0,0 +1,53 @@
+fun test1() {
+    test1@ for(i in 1..2) {
+        continue@test1
+    }
+}
+
+fun test2() {
+    test2@ while (true) {
+        break@test2
+    }
+}
+
+class Test3 {
+    fun Test3() {
+        Test3@ while (true) {
+            break@Test3
+        }
+    }
+}
+
+fun test4() {
+    break@test4
+}
+
+class Test5 {
+    fun Test5<!SYNTAX!><!> {
+        return@Test5
+    }
+}
+
+class Test6 {
+    fun Test6() {
+        Test6@ while (true) {
+            break@Test6
+        }
+
+        Test6@ while (true) {
+            break@Test6
+        }
+    }
+}
+
+class Test7 {
+    fun Test7() {
+        Test8@ while (true) {
+            break@Test7
+        }
+
+        Test7@ while (true) {
+            break@Test8
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/emptyIf.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/emptyIf.fir.kt
new file mode 100644
index 00000000000..761a023dac8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/emptyIf.fir.kt
@@ -0,0 +1,16 @@
+fun foo(x: Unit) = x
+
+fun test() {
+    if (false);
+    if (true);
+
+    val x = if (false);
+    foo(x)
+
+    val y: Unit = if (false);
+    foo(y)
+
+    foo(<!UNRESOLVED_REFERENCE!>{if (1==1);}()<!>)
+
+    return if (true);
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/forLoopWithNullableRange.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/forLoopWithNullableRange.fir.kt
new file mode 100644
index 00000000000..596d3d773b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/forLoopWithNullableRange.fir.kt
@@ -0,0 +1,16 @@
+class Coll {
+  operator fun iterator(): It = It()
+}
+
+class It {
+  operator fun next() = 1
+  operator fun hasNext() = false
+}
+
+fun test(c: Coll?) {
+  <!INAPPLICABLE_CANDIDATE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (x in c) {}<!>
+
+  if (c != null) {
+    for(x in c) {}
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/forWithNullableIterator.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/forWithNullableIterator.fir.kt
new file mode 100644
index 00000000000..3fa6d25c9b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/forWithNullableIterator.fir.kt
@@ -0,0 +1,12 @@
+class Coll {
+  operator fun iterator(): It? = null
+}
+
+class It {
+  operator fun next() = 1
+  operator fun hasNext() = false
+}
+
+fun test() {
+  <!INAPPLICABLE_CANDIDATE, INAPPLICABLE_CANDIDATE!>for (x in Coll()) {}<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ifElseIntersection.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ifElseIntersection.fir.kt
new file mode 100644
index 00000000000..d36e959db14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ifElseIntersection.fir.kt
@@ -0,0 +1,55 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// See also KT-10896: Wrong inference of if / else result type
+
+interface Option<T>
+class Some<T> : Option<T>
+class None<T> : Option<T>
+
+fun <T> bind(r: Option<T>): Option<T> {
+    return if (r is Some) {
+        // Ideally we should infer Option<T> here (see KT-10896)
+        (if (true) None() else r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Option<T>>() }
+        // Works correctly
+        if (true) None() else r
+    }
+    else r
+}
+
+fun <T> bind2(r: Option<T>): Option<T> {
+    return if (r is Some) {
+        // Works correctly
+        if (true) None<T>() else r
+    }
+    else r
+}
+
+fun <T, R> bind3(r: Option<T>): Option<T> {
+    return if (r is Some) {
+        // Diagnoses an error correctly
+        if (true) None<R>() else r
+    }
+    else r
+}
+
+fun <T> bindWhen(r: Option<T>): Option<T> {
+    return when (r) {
+        is Some -> {
+            // Works correctly
+            if (true) None() else r
+        }
+        else -> r
+    }
+}
+
+interface SimpleOption
+class SimpleSome : SimpleOption
+class SimpleNone : SimpleOption
+
+fun bindNoGeneric(r: SimpleOption): SimpleOption {
+    return if (r is SimpleSome) {
+        (if (true) SimpleNone() else r) checkType { <!UNRESOLVED_REFERENCE!>_<!><SimpleOption>() }
+        if (true) SimpleNone() else r
+    }
+    else r
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ifInResultOfLambda.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ifInResultOfLambda.fir.kt
new file mode 100644
index 00000000000..38c443697eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ifInResultOfLambda.fir.kt
@@ -0,0 +1,8 @@
+// !WITH_NEW_INFERENCE
+val test1 = { if (true) 1 else "" }
+
+val test2 = { { if (true) 1 else "" } }
+
+val test3: (Boolean) -> Any = { if (it) 1 else "" }
+
+val test4: (Boolean) -> Any? = { if (it) 1 else "" }
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ifToAnyDiscriminatingUsages.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ifToAnyDiscriminatingUsages.fir.kt
new file mode 100644
index 00000000000..e51b1f00981
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ifToAnyDiscriminatingUsages.fir.kt
@@ -0,0 +1,62 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun println() {}
+fun foo(x: Any) {}
+fun <T> fooGeneric(x: T) {}
+
+fun testResultOfLambda1() =
+        run {
+            if (true) 42 else println()
+        }
+
+fun testResultOfLambda2() =
+        run {
+            if (true) 42 else if (true) 42 else println()
+        }
+
+fun testResultOfAnonFun1() =
+        run(fun () =
+                if (true) 42
+                else println()
+        )
+
+fun testResultOfAnonFun2() =
+        run(fun () {
+            if (true) 42 else println()
+        })
+
+fun testReturnFromAnonFun() =
+        run(fun () {
+            return if (true) 42 else println()
+        })
+
+fun testReturn1() =
+        run {
+            return if (true) 42
+                   else println()
+        }
+
+fun testReturn2() =
+        run {
+            return if (true) 42
+                   else if (true) 42
+                   else println()
+        }
+
+fun testUsage1() =
+        if (true) 42
+        else println()
+
+fun testUsage2() =
+        foo(if (true) 42 else println())
+
+fun testUsage2Generic() =
+        fooGeneric(if (true) 42 else println())
+
+val testUsage3 =
+        if (true) 42
+        else println()
+
+val testUsage4: Any get() =
+        if (true) 42 else println()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ifWhenToAnyComplexExpressions.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ifWhenToAnyComplexExpressions.fir.kt
new file mode 100644
index 00000000000..bd173b19cde
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ifWhenToAnyComplexExpressions.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun println() {}
+fun foo(x: Any) {}
+fun <T> fooGeneric(x: T) {}
+
+fun testMixedIfAndWhen() =
+        if (true)
+            when {
+                true -> if (true) 42
+                else 1
+                    true -> if (true) 42
+                else println()
+                else -> if (true) println()
+            }
+        else println()
+
+fun testWrappedExpressions() =
+        if (true) {
+            println()
+            if (true) {
+                println()
+                if (true) {
+                    println()
+                }
+                else {}
+            }
+        }
+        else {
+            (((((42)) + 1)))
+        }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/ifWhenWithoutElse.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/ifWhenWithoutElse.fir.kt
new file mode 100644
index 00000000000..ee00a4e882d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/ifWhenWithoutElse.fir.kt
@@ -0,0 +1,86 @@
+// !WITH_NEW_INFERENCE
+fun idAny(x: Any) = x
+fun <T> id(x: T) = x
+fun idUnit(x: Unit) = x
+
+class MList {
+    // MutableCollection<T>.add returns Boolean, but nobody cares
+    fun add(): Boolean = true
+}
+val mlist = MList()
+
+fun work() {}
+
+val xx1 = if (true) 42
+val xx2: Unit = if (true) 42
+val xx3 = idAny(if (true) 42)
+val xx4 = id(if (true) 42)
+val xx5 = idUnit(if (true) 42)
+val xx6 = null ?: if (true) 42
+val xx7 = "" + if (true) 42
+
+val wxx1 = when { true -> 42 }
+val wxx2: Unit = when { true -> 42 }
+val wxx3 = idAny(when { true -> 42 })
+val wxx4 = id(when { true -> 42 })
+val wxx5 = idUnit(when { true -> 42 })
+val wxx6 = null ?: when { true -> 42 }
+val wxx7 = "" + when { true -> 42 }
+
+val fn1 = { if (true) 42 }
+val fn2 = { if (true) mlist.add() }
+val fn3 = { if (true) work() }
+val fn4 = { when { true -> 42 } }
+val fn5 = { when { true -> mlist.add() } }
+val fn6 = { when { true -> work() } }
+
+val ufn1: () -> Unit = { if (true) 42 }
+val ufn2: () -> Unit = { if (true) mlist.add() }
+val ufn3: () -> Unit = { if (true) work() }
+val ufn4: () -> Unit = { when { true -> 42 } }
+val ufn5: () -> Unit = { when { true -> mlist.add() } }
+val ufn6: () -> Unit = { when { true -> work() } }
+
+fun f1() = if (true) work()
+fun f2() = if (true) mlist.add()
+fun f3() = if (true) 42
+fun f4(): Unit = if (true) work()
+fun f5(): Unit = if (true) mlist.add()
+fun f6(): Unit = if (true) 42
+fun g1() = when { true -> work() }
+fun g2() = when { true -> mlist.add() }
+fun g3() = when { true -> 42 }
+fun g4(): Unit = when { true -> work() }
+fun g5(): Unit = when { true -> mlist.add() }
+fun g6(): Unit = when { true -> 42 }
+
+fun foo1(x: String?) {
+    "" + if (true) 42
+    w@while (true) {
+        x ?: if (true) break
+        x ?: when { true -> break@w }
+    }
+}
+
+fun foo2() {
+    if (true) {
+        mlist.add()
+    }
+    else if (true) {
+        mlist.add()
+    }
+    else if (true) {
+        mlist.add()
+    }
+
+    when {
+        true -> mlist.add()
+        else -> when {
+            true -> mlist.add()
+            else -> when {
+                true -> mlist.add()
+            }
+        }
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/controlStructures/improperElseInExpression.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/improperElseInExpression.fir.kt
new file mode 100644
index 00000000000..b5d318da51f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/improperElseInExpression.fir.kt
@@ -0,0 +1,34 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun example() {
+    val a = if (true) true else false
+    val b = if (true) else false
+    val c = if (true) true
+    val d = if (true) true else;
+    val e = if (true) {} else false
+    val f = if (true) true else {}
+
+    <!UNRESOLVED_REFERENCE!>{
+        if (true) true
+    }()<!>;
+
+    <!UNRESOLVED_REFERENCE!>{
+        if (true) true else false
+    }()<!>;
+
+    <!UNRESOLVED_REFERENCE!>{
+        if (true) {} else false
+    }()<!>;
+
+
+    <!UNRESOLVED_REFERENCE!>{
+        if (true) true else {}
+    }()<!>
+
+    fun t(): Boolean {
+        return if (true) true
+    }
+
+    return if (true) true else {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/jumpAcrossFunctionBoundary.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/jumpAcrossFunctionBoundary.fir.kt
new file mode 100644
index 00000000000..188f881d28d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/jumpAcrossFunctionBoundary.fir.kt
@@ -0,0 +1,17 @@
+fun call(f: () -> Unit) = f()
+
+fun f1() {
+    outer@ while (true) {
+        call {
+            break@outer
+        }
+    }
+}
+
+fun f2() {
+    do {
+        fun inner() {
+            continue
+        }
+    } while (true)
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt10322.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt10322.fir.kt
new file mode 100644
index 00000000000..42d730e7515
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt10322.fir.kt
@@ -0,0 +1,10 @@
+fun test1() {
+    run {
+        if (true) {
+            if (true) {}
+        }
+        else {
+            1
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt10706.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt10706.fir.kt
new file mode 100644
index 00000000000..3f6ff3a7a21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt10706.fir.kt
@@ -0,0 +1,10 @@
+fun fn(c: Char?): Any? =
+        if (c == null) TODO()
+        else when (c) {
+            'a' -> when (c) {
+                'B' -> 1
+                'C' -> "sdf"
+                else -> TODO()
+            }
+            else -> TODO()
+        }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt10717.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt10717.fir.kt
new file mode 100644
index 00000000000..1389d9e036d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt10717.fir.kt
@@ -0,0 +1,47 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNREACHABLE_CODE -UNUSED_PARAMETER -RETURN_NOT_ALLOWED
+
+fun test1() = run {
+    return "OK"
+}
+
+fun test2() = run {
+    fun local(): String {
+        return ""
+    }
+    return ""
+}
+
+inline fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> = null!!
+fun test3(a: List<String>, b: List<Int>) = a.map {
+    if (it.length == 3) return null
+    if (it.length == 4) return ""
+    if (it.length == 4) return 5
+    if (it.length == 4) return b
+    1
+}
+
+fun test4() = run {
+    fun test5() {
+        return
+
+        return@test4
+
+        return return@test4
+
+        return fun() { return; return@test4 "" }
+    }
+
+    return
+    3
+}
+
+val foo: Int
+    get() = run {
+        if (true) return ""
+
+        return
+    }
+
+fun test(): Int = run {
+    return ""
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt1075.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt1075.fir.kt
new file mode 100644
index 00000000000..6883418762e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt1075.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+package kt1075
+
+//KT-1075 No type check for 'in range' condition in 'when' expression
+
+fun foo(b: String) {
+    if (b <!INAPPLICABLE_CANDIDATE!>in<!> 1..10) {} //type mismatch
+    when (b) {
+        <!INAPPLICABLE_CANDIDATE!>in<!> 1..10 -> 1 //no type mismatch, but it should be here
+        else -> 2
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt30406.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt30406.fir.kt
new file mode 100644
index 00000000000..84e3d4291e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt30406.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// !CHECK_TYPE
+// Issue: KT-30406
+
+interface Option<out T> {
+    val s: String
+}
+class Some<T>(override val s: String) : Option<T>
+class None(override val s: String = "None") : Option<Int>
+
+fun test(a: Int): Option<Any> =
+    if (a == 239)
+        Some("239")
+    else
+        None()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt4310.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt4310.fir.kt
new file mode 100644
index 00000000000..4096d674340
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt4310.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+package f
+
+fun test(a: Boolean, b: Boolean): Int {
+    return if(a) {
+        1
+    } else {
+        if (b) {
+            3
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt657.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt657.fir.kt
new file mode 100644
index 00000000000..4e9d18ad852
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt657.fir.kt
@@ -0,0 +1,20 @@
+//KT-657 Semantic checks for when without condition
+package kt657
+
+class Pair<A, B>(a: A, b: B)
+
+fun foo() =
+    when {
+        cond1() -> 12
+        cond2() -> 2
+        4 -> 34
+        Pair(1, 2) -> 3
+        in 1..10 -> 34
+        4 -> 38
+        is Int -> 33
+        else -> 34
+    }
+
+fun cond1() = false
+
+fun cond2() = true
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt770.fir.kt351.fir.kt735_StatementType.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt770.fir.kt351.fir.kt735_StatementType.fir.kt
new file mode 100644
index 00000000000..04ddcacfd16
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt770.fir.kt351.fir.kt735_StatementType.fir.kt
@@ -0,0 +1,163 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+package kt770_351_735
+
+
+//KT-770 Reference is not resolved to anything, but is not marked unresolved
+fun main() {
+    var i = 0
+    when (i) {
+        1 -> i--
+        2 -> i = 2  // i is surrounded by a black border
+        else -> <!UNRESOLVED_REFERENCE!>j<!> = 2
+    }
+    System.out.println(i)
+}
+
+//KT-351 Distinguish statement and expression positions
+val w = <!INFERENCE_ERROR, INFERENCE_ERROR, INFERENCE_ERROR!>while (true) {}<!>
+
+fun foo() {
+    var z = 2
+    val r = {  // type fun(): Any is inferred
+        if (true) {
+            2
+        }
+        else {
+            z = 34
+        }
+    }
+    val f: ()-> Int = r
+    val g: ()-> Any = r
+}
+
+//KT-735 Statements without braces are prohibited on the right side of when entries.
+fun box() : Int {
+    val d = 2
+    var z = 0
+    when(d) {
+        5, 3 -> z++
+        else -> z = -1000
+    }
+    return z
+}
+
+//More tests
+
+fun test1() { while(true) {} }
+fun test2(): Unit { while(true) {} }
+
+fun testCoercionToUnit() {
+    val simple: ()-> Unit = {
+        41
+    }
+    val withIf: ()-> Unit = {
+        if (true) {
+            3
+        } else {
+            45
+        }
+    }
+    val i = 34
+    val withWhen : () -> Unit = {
+        when(i) {
+            1 -> {
+                val d = 34
+                "1"
+                doSmth(d)
+
+            }
+            2 -> '4'
+            else -> true
+        }
+    }
+
+    var x = 43
+    val checkType = {
+        if (true) {
+            x = 4
+        } else {
+            45
+        }
+    }
+    val f : () -> String = checkType
+}
+
+fun doSmth(i: Int) {}
+
+fun testImplicitCoercion() {
+    val d = 21
+    var z = 0
+    var i = when(d) {
+        3 -> null
+        4 -> { val z = 23 }
+        else -> z = 20
+    }
+
+    var u = when(d) {
+        3 -> {
+        z = 34
+    }
+        else -> z--
+    }
+
+    var iff = if (true) {
+        z = 34
+    }
+    val g = if (true) 4
+    val h = if (false) 4 else {}
+
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(if (true) {
+        4
+    }
+        else {
+        z = 342
+    })
+}
+
+fun fooWithAnyArg(arg: Any) {}
+fun fooWithAnyNullableArg(arg: Any?) {}
+
+fun testCoercionToAny() {
+    val d = 21
+    val x1: Any = if (1>2) 1 else 2.0
+    val x2: Any? = if (1>2) 1 else 2.0
+    val x3: Any? = if (1>2) 1 else (if (1>2) null else 2.0)
+
+    fooWithAnyArg(if (1>2) 1 else 2.0)
+    fooWithAnyNullableArg(if (1>2) 1 else 2.0)
+    fooWithAnyNullableArg(if (1>2) 1 else (if (1>2) null else 2.0))
+
+    val y1: Any = when(d) { 1 -> 1.0 else -> 2.0 }
+    val y2: Any? = when(d) { 1 -> 1.0 else -> 2.0 }
+    val y3: Any? = when(d) { 1 -> 1.0; 2 -> null; else -> 2.0 }
+
+    fooWithAnyArg(when(d) { 1 -> 1.0 else -> 2.0 })
+    fooWithAnyNullableArg(when(d) { 1 -> 1.0 else -> 2.0 })
+    fooWithAnyNullableArg(when(d) { 1 -> 1.0; 2 -> null; else -> 2.0 })
+}
+
+fun fooWithAnuNullableResult(s: String?, name: String, optional: Boolean): Any? {
+    return if (s == null) {
+        if (!optional) {
+            throw java.lang.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>("Parameter '$name' was not found in the request")
+        }
+        null
+    } else {
+        name
+    }
+}
+
+fun bar(a: Unit) {}
+
+fun testStatementInExpressionContext() {
+    var z = 34
+    val a1: Unit = <!INFERENCE_ERROR!>z = 334<!>
+    val f = for (i in 1..10) {}
+    if (true) return <!INFERENCE_ERROR, INFERENCE_ERROR!>z = 34<!>
+    return <!INFERENCE_ERROR, INFERENCE_ERROR!>while (true) {}<!>
+}
+
+fun testStatementInExpressionContext2() {
+    val a2: Unit = <!INFERENCE_ERROR!>while(true) {}<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt786.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt786.fir.kt
new file mode 100644
index 00000000000..26d6aeb6e5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt786.fir.kt
@@ -0,0 +1,26 @@
+package kt786
+
+//KT-786 Exception on incomplete code with 'when'
+fun foo() : Int {
+    val d = 2
+    var z = 0
+    when(d) {
+        5, 3 -> z++
+        else -> { z = -1000 }
+        return z -> 34
+    }
+}
+
+//test unreachable code
+fun fff(): Int {
+    var d = 3
+    when(d) {
+        4 -> 21
+        return 2 -> return 47
+        bar() -> 45
+        444 -> true
+    }
+    return 34
+}
+
+fun bar(): Int = 8
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/kt799.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/kt799.fir.kt
new file mode 100644
index 00000000000..27b31997a8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/kt799.fir.kt
@@ -0,0 +1,25 @@
+//KT-799 Allow 'return' expressions in conditionals assigned to variables
+
+package kt799
+
+fun test() {
+    val a : Int = if (true) 6 else return // should be allowed
+
+    val b = if (true) 6 else return // should be allowed
+
+    doSmth(if (true) 3 else return)
+
+    <!INAPPLICABLE_CANDIDATE!>doSmth<!>(if (true) 3 else return, 1)
+}
+
+val a : Nothing = return 1
+
+val b = return 1
+
+val c = doSmth(if (true) 3 else return)
+
+
+fun f(mi: Int = if (true) 0 else return) {}
+
+fun doSmth(i: Int) {
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/lambdasInExclExclAndElvis.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/lambdasInExclExclAndElvis.fir.kt
new file mode 100644
index 00000000000..f4dc5a89eb4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/lambdasInExclExclAndElvis.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+fun use(a: Any?) = a
+
+fun test() {
+    { }!!
+    use({ }!!);
+
+    // KT-KT-9070
+    { } ?: 1
+    use({ 2 } ?: 1);
+
+    1 ?: { }
+    use(1 ?: { })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/localReturnInsidePropertyAccessor.fir.fail b/compiler/testData/diagnostics/tests/controlStructures/localReturnInsidePropertyAccessor.fir.fail
index d94cf374132..d552b3e6439 100644
--- a/compiler/testData/diagnostics/tests/controlStructures/localReturnInsidePropertyAccessor.fir.fail
+++ b/compiler/testData/diagnostics/tests/controlStructures/localReturnInsidePropertyAccessor.fir.fail
@@ -1,2 +1,2 @@
-Failures detected in FirImplicitTypeBodyResolveTransformerAdapter, file: /localReturnInsidePropertyAccessor.kt
+Failures detected in FirImplicitTypeBodyResolveTransformerAdapter, file: /localReturnInsidePropertyAccessor.fir.kt
 Cause: kotlin.KotlinNullPointerException
diff --git a/compiler/testData/diagnostics/tests/controlStructures/localReturnInsidePropertyAccessor.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/localReturnInsidePropertyAccessor.fir.kt
new file mode 100644
index 00000000000..310a467d293
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/localReturnInsidePropertyAccessor.fir.kt
@@ -0,0 +1,20 @@
+interface ClassData
+
+fun f() = object : ClassData {
+    val someInt: Int
+        get() {
+            return 5
+        }
+}
+
+fun g() = object : ClassData {
+    init {
+        if (true) {
+            return 0
+        }
+    }
+
+    fun some(): Int {
+        return 6
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.fir.kt
new file mode 100644
index 00000000000..fd20b9f612b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_after.fir.kt
@@ -0,0 +1,62 @@
+// !LANGUAGE: +RestrictReturnStatementTarget
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class Ann
+
+fun testFunctionName() {
+    return@testFunctionName
+}
+
+fun testHighOrderFunctionName() {
+    run {
+        return@run
+    }
+}
+
+fun testLambdaLabel() =
+    lambda@ {
+        return@lambda
+    }
+
+fun testParenthesizedLambdaLabel() =
+    lambda@ ( {
+        return@lambda
+    } )
+
+fun testAnnotatedLambdaLabel() =
+    lambda@ @Ann {
+        return@lambda
+    }
+
+fun testLambdaMultipleLabels1() =
+    lambda1@ lambda2@ {
+        return@lambda1
+    }
+
+fun testLambdaMultipleLabels2() =
+    lambda1@ lambda2@ {
+        return@lambda2
+    }
+
+fun testAnonymousFunctionLabel() =
+    anonFun@ fun() {
+        return@anonFun
+    }
+
+fun testLoopLabelInReturn(xs: List<Int>) {
+    L@ for (x in xs) {
+        if (x > 0) return@L
+    }
+}
+
+fun testValLabelInReturn() {
+    L@ val fn = { return@L }
+    fn()
+}
+
+fun testHighOrderFunctionCallLabelInReturn() {
+    L@ run {
+        return@L
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.fir.kt
new file mode 100644
index 00000000000..1a09741d73d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/notAFunctionLabel_before.fir.kt
@@ -0,0 +1,62 @@
+// !LANGUAGE: -RestrictReturnStatementTarget
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class Ann
+
+fun testFunctionName() {
+    return@testFunctionName
+}
+
+fun testHighOrderFunctionName() {
+    run {
+        return@run
+    }
+}
+
+fun testLambdaLabel() =
+    lambda@ {
+        return@lambda
+    }
+
+fun testParenthesizedLambdaLabel() =
+    lambda@ ( {
+        return@lambda
+    } )
+
+fun testAnnotatedLambdaLabel() =
+    lambda@ @Ann {
+        return@lambda
+    }
+
+fun testLambdaMultipleLabels1() =
+    lambda1@ lambda2@ {
+        return@lambda1
+    }
+
+fun testLambdaMultipleLabels2() =
+    lambda1@ lambda2@ {
+        return@lambda2
+    }
+
+fun testAnonymousFunctionLabel() =
+    anonFun@ fun() {
+        return@anonFun
+    }
+
+fun testLoopLabelInReturn(xs: List<Int>) {
+    L@ for (x in xs) {
+        if (x > 0) return@L
+    }
+}
+
+fun testValLabelInReturn() {
+    L@ val fn = { return@L }
+    fn()
+}
+
+fun testHighOrderFunctionCallLabelInReturn() {
+    L@ run {
+        return@L
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.fir.kt
new file mode 100644
index 00000000000..84449239afa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/redundantLabel.fir.kt
@@ -0,0 +1,39 @@
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class Ann
+
+fun testLambdaLabel() = l@ { 42 }
+
+fun testAnonymousFunctionLabel() = l@ fun() {}
+
+fun testAnnotatedLambdaLabel() = lambda@ @Ann {}
+
+fun testParenthesizedLambdaLabel() = lambda@ ( {} )
+
+fun testLabelBoundToInvokeOperatorExpression() = l@ <!UNRESOLVED_REFERENCE!>{ 42 }()<!>
+
+fun testLabelBoundToLambda() = <!UNRESOLVED_REFERENCE!>(l@ { 42 })()<!>
+
+fun testWhileLoopLabel() {
+    L@ while (true) {}
+}
+
+fun testDoWhileLoopLabel() {
+    L@ do {} while (true)
+}
+
+fun testForLoopLabel(xs: List<Any>) {
+    L@ for (x in xs) {}
+}
+
+fun testValLabel() {
+    L@ val fn = {}
+    fn()
+}
+
+fun testHighOrderFunctionCallLabel() {
+    L@ run {}
+}
+
+fun testAnonymousObjectLabel() =
+    L@ object {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/specialConstructsAndPlatformTypes.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/specialConstructsAndPlatformTypes.fir.kt
new file mode 100644
index 00000000000..133ac6dee04
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/specialConstructsAndPlatformTypes.fir.kt
@@ -0,0 +1,40 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+import java.util.*;
+
+public class J {
+    public static String s = null;
+    public static Map<String, String> m = null;
+}
+
+// FILE: k.kt
+
+val testImplicitExclExcl1: String = J.s
+val testImplicitExclExcl2: String? = J.s
+
+val testImplicitExclExcl3: String = J.m[""]
+val testImplicitExclExcl4: String? = J.m[""]
+
+val testExclExcl1: String = J.s!!
+val testExclExcl2: String? = J.s!!
+
+val testExclExcl3: String = J.m[""]!!
+val testExclExcl4: String? = J.m[""]!!
+
+val testSafeCall1: String = J.s?.let { it }
+val testSafeCall2: String? = J.s?.let { it }
+
+val testSafeCall3: String = J.m[""]?.let { it }
+val testSafeCall4: String? = J.m[""]?.let { it.toString() }
+
+val testIf1: String = if (true) J.s else J.s
+val testIf2: String? = if (true) J.s else J.s
+
+val testIf3: String = if (true) J.m[""] else J.m[""]
+val testIf4: String? = if (true) J.m[""] else J.m[""]
+
+val testWhen1: String = when { else -> J.s }
+val testWhen2: String? = when { else -> J.s }
+
+val testWhen3: String = when { else -> J.m[""] }
+val testWhen4: String? = when { else -> J.m[""] }
diff --git a/compiler/testData/diagnostics/tests/controlStructures/specialConstructsWithNullableExpectedType.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/specialConstructsWithNullableExpectedType.fir.kt
new file mode 100644
index 00000000000..0e8ec5e19de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/specialConstructsWithNullableExpectedType.fir.kt
@@ -0,0 +1,20 @@
+val ns: String? = null
+
+val testElvis1: String? = ns ?: ""
+val testElvis2: String = run { ns ?: "" }
+val testElvis3: String? = run { ns ?: "" }
+
+val testIf1: String? = if (true) "" else ""
+val testIf2: String? = run { if (true) "" else "" }
+val testIf3: String? = if (true) run { "" } else ""
+val testIf4: String? = run { run { if (true) "" else "" } }
+val testIf5: String? = run { if (true) run { "" } else "" }
+
+val testWhen1: String? = when { else -> "" }
+val testWhen2: String? = run { when { else -> "" } }
+val testWhen3: String? = when { else -> run { "" } }
+val testWhen4: String? = run { run { when { else -> "" } } }
+val testWhen5: String? = run { when { else -> run { "" } } }
+
+val testExcl1: String? = run { ns!! }
+val testExcl2: String? = run { run { ns!! } }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/tryReturnType.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/tryReturnType.fir.kt
new file mode 100644
index 00000000000..77b157a446e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/tryReturnType.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+package a
+
+fun foo() : Int {
+    try {
+        doSmth()
+    }
+    catch (e: Exception) {
+        return ""
+    }
+    finally {
+        return ""
+    }
+}
+
+fun bar() : Int =
+    try {
+        doSmth()
+    }
+    catch (e: Exception) {
+        ""
+    }
+    finally {
+        ""
+    }
+
+
+fun doSmth() {}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.fir.kt
new file mode 100644
index 00000000000..b136b408f54
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public static String foo() {
+        return "";
+    }
+}
+
+// FILE: b.kt
+fun <T: Any> exclExcl(t: T?): T = t!!
+
+fun test11() {
+    // not 'String!'
+    exclExcl(A.foo()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    exclExcl(A.foo()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+
+    // not 'String!'
+    A.foo()!! checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    A.foo()!! checkType { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/valVarCatchParameter.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/valVarCatchParameter.fir.kt
new file mode 100644
index 00000000000..f9b78e45309
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/valVarCatchParameter.fir.kt
@@ -0,0 +1,13 @@
+fun f() {
+    try {
+    } catch (val e: Exception) {
+    }
+
+    try {
+    } catch (var e: Exception) {
+    }
+
+    try {
+    } catch (e: Exception) {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/valVarLoopParameter.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/valVarLoopParameter.fir.kt
new file mode 100644
index 00000000000..54716ccce9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/valVarLoopParameter.fir.kt
@@ -0,0 +1,32 @@
+class Pair {
+    operator fun component1(): Int = null!!
+    operator fun component2(): Int = null!!
+}
+
+class Coll {
+    operator fun iterator(): It = It()
+}
+
+class It {
+    operator fun next() = Pair()
+    operator fun hasNext() = false
+}
+
+
+fun f() {
+    for (val i in 1..4) {
+
+    }
+
+    for (var i in 1..4) {
+
+    }
+
+    for (val (i,j) in Coll()) {
+
+    }
+
+    for (var (i,j) in Coll()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/when.fir.kt234.fir.kt973.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/when.fir.kt234.fir.kt973.fir.kt
new file mode 100644
index 00000000000..b7fb0ec8796
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/when.fir.kt234.fir.kt973.fir.kt
@@ -0,0 +1,41 @@
+//KT-234 Force when() expressions to have an 'else' branch
+//KT-973 Unreachable code
+
+package kt234_kt973
+
+class Pair<A, B>(a: A, b: B)
+
+fun test(t : Pair<Int, Int>) : Int {
+    when (t) {
+        Pair(10, 10) -> return 1
+    }
+    return 0 // unreachable code
+}
+
+fun test1(t : Pair<Int, Int>) : Int {
+    when (t) {
+        Pair(10, 10) -> return 1
+        else -> return 2
+    }
+    return 0 // unreachable code
+}
+
+//more tests
+fun t1(x: Int) = when(x) {
+    else -> 1
+}
+
+fun t5(x: Int) = when (x) {
+    is Int -> 1
+    2 -> 2
+}
+
+fun foo3(x: Int) = when(x) {
+    else -> 1
+    2 -> 2
+}
+
+fun foo4(x: Int) = when(x) {
+    2 -> x
+    else -> 3
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/whenInResultOfLambda.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/whenInResultOfLambda.fir.kt
new file mode 100644
index 00000000000..f7373d7a573
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/whenInResultOfLambda.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+val test1 = { when (true) { true -> 1; else -> "" } }
+
+val test2 = { { when (true) { true -> 1; else -> "" } } }
+
+val test3: (Boolean) -> Any = { when (true) { true -> 1; else -> "" } }
+
+val test4: (Boolean) -> Any? = { when (true) { true -> 1; else -> "" } }
+
+fun println() {}
+
+val test5 = {
+    when (true) {
+        true -> println()
+        else -> println()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/controlStructures/whenToAnyDiscriminatingUsages.fir.kt b/compiler/testData/diagnostics/tests/controlStructures/whenToAnyDiscriminatingUsages.fir.kt
new file mode 100644
index 00000000000..96c68ac62d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/whenToAnyDiscriminatingUsages.fir.kt
@@ -0,0 +1,83 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun println() {}
+fun foo(x: Any) {}
+fun <T> fooGeneric(x: T) {}
+
+fun testResultOfLambda1() =
+        run {
+            when {
+                true -> 42
+                else -> println()
+            }
+        }
+
+fun testResultOfLambda2() =
+        run {
+            when {
+                true -> 42
+                else ->
+                    when {
+                        true -> 42
+                        else -> println()
+                    }
+            }
+        }
+
+fun testReturn1() =
+        run {
+            return when {
+                true -> 42
+                else -> println()
+            }
+        }
+
+fun testReturn2() =
+        run {
+            return when {
+                true -> 42
+                else ->
+                    when {
+                        true -> 42
+                        else -> println()
+                    }
+            }
+        }
+
+fun testUsage1() =
+        when {
+            true -> 42
+            else -> println()
+        }
+
+fun testUsage2() =
+        foo(when {
+                true -> 42
+                else -> println()
+            })
+
+fun testUsage2Generic() =
+        fooGeneric(when {
+                       true -> 42
+                       else -> println()
+                   })
+
+val testUsage3 =
+        when {
+            true -> 42
+            else -> println()
+        }
+
+val testUsage4 =
+        when {
+            true -> 42
+            true -> 42
+            true -> 42
+            else -> println()
+        }
+
+val testUsage5: Any get() =
+        when {
+            true -> 42
+            else -> println()
+        }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/coroutines/callableReference/invokeOutideSuspend.fir.kt b/compiler/testData/diagnostics/tests/coroutines/callableReference/invokeOutideSuspend.fir.kt
new file mode 100644
index 00000000000..a335dcf87c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/coroutines/callableReference/invokeOutideSuspend.fir.kt
@@ -0,0 +1,8 @@
+// !LANGUAGE: +Coroutines
+// SKIP_TXT
+
+import kotlin.reflect.KSuspendFunction0
+
+fun test(c: KSuspendFunction0<Unit>) {
+    c()
+}
diff --git a/compiler/testData/diagnostics/tests/coroutines/callableReference/outsideSuspend.fir.kt b/compiler/testData/diagnostics/tests/coroutines/callableReference/outsideSuspend.fir.kt
new file mode 100644
index 00000000000..a3c6e936dbf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/coroutines/callableReference/outsideSuspend.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+// !LANGUAGE: +ReleaseCoroutines
+// SKIP_TXT
+
+import kotlin.reflect.KSuspendFunction0
+
+suspend fun foo() {}
+
+fun test() {
+    ::foo checkType { <!UNRESOLVED_REFERENCE!>_<!><KSuspendFunction0<Unit>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/classIndirectlyInheritsNested.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/classIndirectlyInheritsNested.fir.kt
new file mode 100644
index 00000000000..3eb40751586
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/classIndirectlyInheritsNested.fir.kt
@@ -0,0 +1,4 @@
+open class C : D() {
+    open class CC
+}
+open class D : C.CC()
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/classInheritsNested.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/classInheritsNested.fir.kt
new file mode 100644
index 00000000000..8fa8ed8d9d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/classInheritsNested.fir.kt
@@ -0,0 +1,3 @@
+open class E : E.EE() {
+    open class EE
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicAndUsualTypes.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicAndUsualTypes.fir.kt
new file mode 100644
index 00000000000..77feb341b84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicAndUsualTypes.fir.kt
@@ -0,0 +1,8 @@
+open class A : B()
+open class B : <!OTHER_ERROR!>A<!>()
+
+fun <T> select(vararg xs: T): T = xs[0]
+
+fun foo() {
+    val x = select(A(), B(), "foo")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicTypes.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicTypes.fir.kt
new file mode 100644
index 00000000000..0f45068f764
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/commonSupertypeForCyclicTypes.fir.kt
@@ -0,0 +1,8 @@
+open class A : B()
+open class B : <!OTHER_ERROR!>A<!>()
+
+fun <T> select(vararg xs: T): T = xs[0]
+
+fun foo() {
+    select(A(), B())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/cyclicHierarchy.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/cyclicHierarchy.fir.kt
new file mode 100644
index 00000000000..0eaf10e17e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/cyclicHierarchy.fir.kt
@@ -0,0 +1,30 @@
+interface A {
+    fun foo() {}
+}
+interface B : A, E {}
+interface C : <!OTHER_ERROR!>B<!> {}
+interface D : <!OTHER_ERROR!>B<!> {}
+interface E : F {}
+interface F : D, C {}
+interface G : F {}
+interface H : F {}
+
+val a : A? = null
+val b : B? = null
+val c : C? = null
+val d : D? = null
+val e : E? = null
+val f : F? = null
+val g : G? = null
+val h : H? = null
+
+fun test() {
+    a?.foo()
+    b?.foo()
+    c?.<!UNRESOLVED_REFERENCE!>foo<!>()
+    d?.<!UNRESOLVED_REFERENCE!>foo<!>()
+    e?.<!UNRESOLVED_REFERENCE!>foo<!>()
+    f?.<!UNRESOLVED_REFERENCE!>foo<!>()
+    g?.<!UNRESOLVED_REFERENCE!>foo<!>()
+    h?.<!UNRESOLVED_REFERENCE!>foo<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/javaJavaCycle.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/javaJavaCycle.fir.kt
new file mode 100644
index 00000000000..f7631022981
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/javaJavaCycle.fir.kt
@@ -0,0 +1,28 @@
+// FILE: A.java
+
+public interface A extends A {
+    int getFoo();
+}
+
+// FILE: B.java
+
+public class B {
+    interface B1 extends B2 {
+        int getFoo();
+    }
+    interface B2 extends B3 {
+        int getFoo();
+    }
+    interface B3 extends B2 {
+        int getFoo();
+    }
+}
+
+// FILE: main.kt
+fun foo() {
+    object : A { override fun getFoo() = 1 }
+    object : B.B1 { override fun getFoo() = 1 }
+    object : B.B2 { override fun getFoo() = 1 }
+    object : B.B3 { override fun getFoo() = 1 }
+}
+
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/javaJavaNested.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/javaJavaNested.fir.kt
new file mode 100644
index 00000000000..82a5d2f8eb6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/javaJavaNested.fir.kt
@@ -0,0 +1,24 @@
+// FILE: A.java
+
+public interface A extends A.B {
+    interface B extends A { public int getFoo() { return 1; } }
+}
+
+// FILE: A0.java
+public interface A0 extends A0.B {
+    interface B { public int getFoo() { return 1; } }
+}
+
+// FILE: B.java
+
+public class B extends D {
+    public int getFoo() { return 1; }
+    public static class C {
+        public int getFoo() { return 1; }
+    }
+}
+
+// FILE: D.java
+public class D extends B.C {
+    public int getFoo() { return 1; }
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/javaKotlinJavaCycle.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/javaKotlinJavaCycle.fir.kt
new file mode 100644
index 00000000000..12cc4ee45a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/javaKotlinJavaCycle.fir.kt
@@ -0,0 +1,17 @@
+// FILE: A.java
+
+interface A extends C {
+    void foo();
+}
+
+// FILE: B.kt
+
+interface B : A {
+    fun bar()
+}
+
+// FILE: C.java
+
+interface C extends B {
+    void baz();
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaCycle.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaCycle.fir.kt
new file mode 100644
index 00000000000..e05df739ef9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaCycle.fir.kt
@@ -0,0 +1,11 @@
+// FILE: J.java
+
+class J extends K {
+    void foo() {}
+}
+
+// FILE: K.kt
+
+class K : <!AMBIGUITY!>J<!>() {
+    fun bar() {}
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaKotlinCycle.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaKotlinCycle.fir.kt
new file mode 100644
index 00000000000..c805d4c1799
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaKotlinCycle.fir.kt
@@ -0,0 +1,17 @@
+// FILE: I.kt
+
+open class I : <!AMBIGUITY!>K<!>() {
+    fun foo() {}
+}
+
+// FILE: J.java
+
+class J extends I {
+    void bar() {}
+}
+
+// FILE: K.kt
+
+open class K : <!AMBIGUITY!>J<!>() {
+    fun baz() {}
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaNestedCycle.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaNestedCycle.fir.kt
new file mode 100644
index 00000000000..bcd66b00875
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/kotlinJavaNestedCycle.fir.kt
@@ -0,0 +1,21 @@
+// FILE: ExceptionTracker.kt
+
+interface ExceptionTracker : LockBasedStorageManager.ExceptionHandlingStrategy {
+}
+
+// FILE: StorageManager.kt
+
+interface StorageManager : ExceptionTracker {
+    fun foo()
+}
+
+// FILE: LockBasedStorageManager.java
+
+class LockBasedStorageManager extends StorageManager {
+    interface ExceptionHandlingStrategy {
+        void bar();
+    }
+
+    @Override
+    void foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/kt303.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/kt303.fir.kt
new file mode 100644
index 00000000000..725831b1992
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/kt303.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// KT-303 Stack overflow on a cyclic class hierarchy
+
+open class Foo() : Bar() {
+  val a : Int = 1
+}
+
+open class Bar() : <!OTHER_ERROR!>Foo<!>() {
+
+}
+
+val x : Int = Foo()
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/nestedClassInSuperClassParameter.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/nestedClassInSuperClassParameter.fir.kt
new file mode 100644
index 00000000000..f33ddf14c37
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/nestedClassInSuperClassParameter.fir.kt
@@ -0,0 +1,5 @@
+open class X<T>
+
+class A: X<A.B>() {
+    class B
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/objectInheritsNested.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/objectInheritsNested.fir.kt
new file mode 100644
index 00000000000..554aa01effa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/objectInheritsNested.fir.kt
@@ -0,0 +1,22 @@
+// As in KT-18514
+object A : A.I {
+    interface I
+}
+
+// Similar to 'classIndirectlyInheritsNested.kt'
+object D : E() {
+    open class NestedD
+}
+
+open class E : D.NestedD()
+
+
+
+// Similar to 'twoClassesWithNestedCycle.kt'
+object G : H.NestedH() {
+    open class NestedG
+}
+object H : G.NestedG() {
+    open class NestedH
+}
+
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/twoClassesWithNestedCycle.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/twoClassesWithNestedCycle.fir.kt
new file mode 100644
index 00000000000..d989abdff0c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/twoClassesWithNestedCycle.fir.kt
@@ -0,0 +1,6 @@
+open class A : B.BB() {
+    open class AA
+}
+open class B : A.AA() {
+    open class BB
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/everythingInOneScope_after.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/everythingInOneScope_after.fir.kt
new file mode 100644
index 00000000000..971fc966757
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/everythingInOneScope_after.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+open class Container {
+    open class Base {
+        open fun m() {}
+    }
+
+    // note that Base() supertype will be resolved in scope that was created on recursion
+    abstract class DerivedAbstract : Base()
+
+    companion object : DerivedAbstract() {
+        override fun m() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/everythingInOneScope_before.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/everythingInOneScope_before.fir.kt
new file mode 100644
index 00000000000..873ec0acf71
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/everythingInOneScope_before.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+open class Container {
+    open class Base {
+        open fun m() {}
+    }
+
+    // note that Base() supertype will be resolved in scope that was created on recursion
+    abstract class DerivedAbstract : Base()
+
+    companion object : DerivedAbstract() {
+        override fun m() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/noMembers_after.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/noMembers_after.fir.kt
new file mode 100644
index 00000000000..e25e2bfd70f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/noMembers_after.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+abstract class DerivedAbstract : C.Base() {
+    open class Data
+}
+
+public class C {
+
+    open class Base ()
+
+    class Foo : Data()
+
+    companion object : DerivedAbstract()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/noMembers_before.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/noMembers_before.fir.kt
new file mode 100644
index 00000000000..7f56616a319
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/noMembers_before.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+abstract class DerivedAbstract : C.Base() {
+    open class Data
+}
+
+public class C {
+
+    open class Base ()
+
+    class Foo : Data()
+
+    companion object : DerivedAbstract()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/onlyInterfaces_after.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/onlyInterfaces_after.fir.kt
new file mode 100644
index 00000000000..350e095af2c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/onlyInterfaces_after.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+open class Container {
+    // Note that here we also have errors and diagnostics, even though there are actually no loops.
+    // (this is case because we can't know if there are any loops without resolving, but resolving
+    // itself provokes loops)
+
+    interface Base {
+        open fun m() {}
+    }
+
+    interface DerivedAbstract : Base
+
+    companion object : DerivedAbstract {
+        override fun m() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/onlyInterfaces_before.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/onlyInterfaces_before.fir.kt
new file mode 100644
index 00000000000..f9d0268fe6f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/onlyInterfaces_before.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+open class Container {
+    // Note that here we also have errors and diagnostics, even though there are actually no loops.
+    // (this is case because we can't know if there are any loops without resolving, but resolving
+    // itself provokes loops)
+
+    interface Base {
+        open fun m() {}
+    }
+
+    interface DerivedAbstract : Base
+
+    companion object : DerivedAbstract {
+        override fun m() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/typeIsLowEnough.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/typeIsLowEnough.fir.kt
new file mode 100644
index 00000000000..e7d57338d70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/typeIsLowEnough.fir.kt
@@ -0,0 +1,20 @@
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+abstract class DerivedAbstract : C.Base() {
+    override abstract fun m()
+}
+
+public class C {
+    class Data
+
+    open class Base () {
+        open fun m() {}
+    }
+
+    // Note that Data is resolved successfully here because we don't step on error-scope
+    val data: Data = Data()
+
+    companion object : DerivedAbstract() {
+        override fun m() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withIrrelevantInterface_after.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withIrrelevantInterface_after.fir.kt
new file mode 100644
index 00000000000..b402ba85820
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withIrrelevantInterface_after.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+interface SomeIrrelevantInterface
+
+// note that C.Base() supertype will be resolved in normal scope
+abstract class DerivedAbstract : C.Base()
+
+class Data
+
+public class C {
+
+    val data: Data = Data()
+
+    // Note that any supertype of Base will be resolved in error-scope, even if it absolutely irrelevant
+    // to the types in cycle.
+    open class Base() : SomeIrrelevantInterface
+
+    companion object : DerivedAbstract()
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withIrrelevantInterface_before.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withIrrelevantInterface_before.fir.kt
new file mode 100644
index 00000000000..a44f2974ea0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withIrrelevantInterface_before.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+interface SomeIrrelevantInterface
+
+// note that C.Base() supertype will be resolved in normal scope
+abstract class DerivedAbstract : C.Base()
+
+class Data
+
+public class C {
+
+    val data: Data = Data()
+
+    // Note that any supertype of Base will be resolved in error-scope, even if it absolutely irrelevant
+    // to the types in cycle.
+    open class Base() : SomeIrrelevantInterface
+
+    companion object : DerivedAbstract()
+}
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withMembers_after.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withMembers_after.fir.kt
new file mode 100644
index 00000000000..4826e4a9fe1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withMembers_after.fir.kt
@@ -0,0 +1,58 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+object WithFunctionInBase {
+    abstract class DerivedAbstract : C.Base()
+
+    class Data
+
+    public class C {
+        val data: Data = Data()
+
+        open class Base() {
+            fun foo(): Int = 42
+        }
+
+        companion object : DerivedAbstract()
+    }
+}
+
+object WithPropertyInBase {
+    // This case is very similar to previous one, but there are subtle differences from POV of implementation
+
+    abstract class DerivedAbstract : C.Base()
+
+    class Data
+
+    public class C {
+
+        open class Base() {
+            val foo: Int = 42
+        }
+
+        val data: Data = Data()
+
+        companion object : DerivedAbstract()
+    }
+}
+
+object WithPropertyInBaseDifferentOrder {
+    // This case is very similar to previous one, but there are subtle differences from POV of implementation
+    // Note how position of property in file affected order of resolve, and, consequently, its results and
+    // diagnostics.
+
+    abstract class DerivedAbstract : C.Base()
+
+    class Data
+
+    public class C {
+        val data: Data = Data()
+
+        open class Base() {
+            val foo: Int = 42
+
+        }
+
+        companion object : DerivedAbstract()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withMembers_before.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withMembers_before.fir.kt
new file mode 100644
index 00000000000..818214fdd83
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withMembers_before.fir.kt
@@ -0,0 +1,64 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+object WithFunctionInBase {
+    abstract class DerivedAbstract : C.Base()
+
+    class Data
+
+    public class C {
+        // error-scope
+        val data: Data = Data()
+
+        open class Base() {
+            // error-scope
+            fun foo(): Int = 42
+        }
+
+        companion object : DerivedAbstract()
+    }
+}
+
+object WithPropertyInBase {
+    // This case is very similar to previous one, but there are subtle differences from POV of implementation
+
+    abstract class DerivedAbstract : C.Base()
+
+    class Data
+
+    public class C {
+
+        open class Base() {
+            // error-scope
+            val foo: Int = 42
+        }
+
+        // error-scope
+        val data: Data = Data()
+
+        companion object : DerivedAbstract()
+    }
+}
+
+object WithPropertyInBaseDifferentOrder {
+    // This case is very similar to previous one, but there are subtle differences from POV of implementation
+    // Note how position of property in file affected order of resolve, and, consequently, its results and
+    // diagnostics.
+
+    abstract class DerivedAbstract : C.Base()
+
+    class Data
+
+    public class C {
+        // Now it is successfully resolved (vs. ErrorType like in the previous case)
+        val data: Data = Data()
+
+        open class Base() {
+            // Now it is unresolved (vs. ErrorType like in the previous case)
+            val foo: Int = 42
+
+        }
+
+        companion object : DerivedAbstract()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withoutTypeReference.fir.kt b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withoutTypeReference.fir.kt
new file mode 100644
index 00000000000..b624ea1f79a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cyclicHierarchy/withCompanion/withoutTypeReference.fir.kt
@@ -0,0 +1,17 @@
+// see https://youtrack.jetbrains.com/issue/KT-21515
+
+abstract class DerivedAbstract : C.Base()
+
+class Data
+
+open class C {
+    open class Base {
+        open fun m() {}
+    }
+
+    val field = Data()
+
+    companion object : DerivedAbstract() {
+        override fun m() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/componentNamedComponent1.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/componentNamedComponent1.fir.kt
new file mode 100644
index 00000000000..045ee011574
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/componentNamedComponent1.fir.kt
@@ -0,0 +1,6 @@
+data class A(val component1: Int)
+
+fun foo(a: A) {
+    a.component1()
+    a.component1
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/conflictingCopyOverloads.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/conflictingCopyOverloads.fir.kt
new file mode 100644
index 00000000000..791c7e10057
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/conflictingCopyOverloads.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+data class A(val x: Int, val y: String) {
+    fun copy(x: Int, y: String) = x
+    fun copy(x: Int, y: String) = A(x, y)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/conflictingOverloads.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/conflictingOverloads.fir.kt
new file mode 100644
index 00000000000..640a34b246d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/conflictingOverloads.fir.kt
@@ -0,0 +1,4 @@
+data class A(val x: Int, val y: String) {
+    fun component1() = 1
+    fun component2() = 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/copyOfPrivateClass.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/copyOfPrivateClass.fir.kt
new file mode 100644
index 00000000000..d4e07be97da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/copyOfPrivateClass.fir.kt
@@ -0,0 +1,3 @@
+class Outer {
+    private data class Nested(val c: Int)
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataClassExplicitlyOverridingCopyNoDefaults.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataClassExplicitlyOverridingCopyNoDefaults.fir.kt
new file mode 100644
index 00000000000..f73857723f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataClassExplicitlyOverridingCopyNoDefaults.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +ProhibitDataClassesOverridingCopy
+
+interface WithCopy<T> {
+    fun copy(str: T): WithCopy<T>
+}
+
+data class Test(val str: String) : WithCopy<String> {
+    override fun copy(str: String) = Test(str)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataClassExplicitlyOverridingCopyWithDefaults.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataClassExplicitlyOverridingCopyWithDefaults.fir.kt
new file mode 100644
index 00000000000..4e62292ae3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataClassExplicitlyOverridingCopyWithDefaults.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +ProhibitDataClassesOverridingCopy
+
+interface WithCopy<T> {
+    fun copy(str: T): WithCopy<T>
+}
+
+data class Test(val str: String) : WithCopy<String> {
+    override fun copy(str: String = this.str) = Test(str)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataClassNoName.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataClassNoName.fir.kt
new file mode 100644
index 00000000000..4c9bb2fe3c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataClassNoName.fir.kt
@@ -0,0 +1,9 @@
+// See EA-73584
+data class<!SYNTAX!><!> {
+
+}
+
+// See KT-9296
+data interface<!SYNTAX!><!> {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataClassNotOverridingCopy.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataClassNotOverridingCopy.fir.kt
new file mode 100644
index 00000000000..aa5c85f6323
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataClassNotOverridingCopy.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +ProhibitDataClassesOverridingCopy
+
+interface WithCopy<T> {
+    fun copy(str: T): WithCopy<T>
+}
+
+data class Test(val str: String, val int: Int) : WithCopy<String> {
+    override fun copy(str: String) = copy(str, int)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataClassOverridingCopy_lv12.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataClassOverridingCopy_lv12.fir.kt
new file mode 100644
index 00000000000..725649fc673
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataClassOverridingCopy_lv12.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: -ProhibitDataClassesOverridingCopy
+
+interface WithCopy<T> {
+    fun copy(str: T): WithCopy<T>
+}
+
+data class Test(val str: String): WithCopy<String>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataClassOverridingCopy_lv13.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataClassOverridingCopy_lv13.fir.kt
new file mode 100644
index 00000000000..78bbb6acfc6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataClassOverridingCopy_lv13.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: +ProhibitDataClassesOverridingCopy
+
+interface WithCopy<T> {
+    fun copy(str: T): WithCopy<T>
+}
+
+data class Test(val str: String): WithCopy<String>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataClassVarargParam.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataClassVarargParam.fir.kt
new file mode 100644
index 00000000000..394aa100f74
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataClassVarargParam.fir.kt
@@ -0,0 +1,3 @@
+data class My(val x: Int, vararg val y: String)
+
+data class Your(vararg z: String)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataInheritance.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataInheritance.fir.kt
new file mode 100644
index 00000000000..c65cabe764d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataInheritance.fir.kt
@@ -0,0 +1,13 @@
+interface SuperInterface
+
+open class SuperClass
+
+abstract data class Base(val x: Int)
+
+class Derived: Base(42)
+
+data class Nasty(val z: Int, val y: Int): Base(z)
+
+data class Complex(val y: Int): SuperInterface, SuperClass()
+
+data class SubData(val sss: String) : Complex(42)
diff --git a/compiler/testData/diagnostics/tests/dataClasses/dataObject.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/dataObject.fir.kt
new file mode 100644
index 00000000000..6fb3b31efdc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/dataObject.fir.kt
@@ -0,0 +1 @@
+data object Object(val x: Int, val y: Int)
diff --git a/compiler/testData/diagnostics/tests/dataClasses/emptyConstructor.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/emptyConstructor.fir.kt
new file mode 100644
index 00000000000..ef979927e6d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/emptyConstructor.fir.kt
@@ -0,0 +1,6 @@
+data class A()
+
+fun foo(a: A) {
+    a.<!UNRESOLVED_REFERENCE!>component1<!>()
+    a.<!UNRESOLVED_REFERENCE!>component2<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/errorTypesInDataClasses.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/errorTypesInDataClasses.fir.kt
new file mode 100644
index 00000000000..2d4f2129a41
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/errorTypesInDataClasses.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+data class A(val i: Int, val j: G)
+data class B(val i: G, val j: G)
+
+
+fun fa(a: A) {
+    val (i, j) = a
+    val i2 = a.component1()
+    val j2 = a.component2()
+}
+
+fun fb(b: B) {
+    val (i, j) = b
+    val i2 = b.component1()
+    val j2 = b.component2()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/extensionComponentsOnNullable.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/extensionComponentsOnNullable.fir.kt
new file mode 100644
index 00000000000..35a91f872ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/extensionComponentsOnNullable.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+class Data<T>(val x: T, val y: T)
+
+operator fun <T> Data<T>.component1() = x
+
+operator fun <T> Data<T>.component2() = y
+
+fun foo(): Int {
+    val d: Data<Int>? = null
+    // An error must be here
+    val (<!INAPPLICABLE_CANDIDATE!>x<!>, <!INAPPLICABLE_CANDIDATE!>y<!>) = d
+    return x + y
+}
+
+data class NormalData<T>(val x: T, val y: T)
+
+fun bar(): Int {
+    val d: NormalData<Int>? = null
+    // An error must be here
+    val (<!INAPPLICABLE_CANDIDATE!>x<!>, <!INAPPLICABLE_CANDIDATE!>y<!>) = d
+    return x + y
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/finalMembersInBaseClass.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/finalMembersInBaseClass.fir.kt
new file mode 100644
index 00000000000..1969596d600
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/finalMembersInBaseClass.fir.kt
@@ -0,0 +1,16 @@
+abstract class Base {
+    final override fun equals(other: Any?) = false
+    final override fun hashCode() = 42
+
+    open override fun toString() = "OK"
+}
+
+data class Data1(val field: String) : Base()
+
+interface AbstractAnyMembers {
+    abstract override fun equals(other: Any?): Boolean
+    abstract override fun hashCode(): Int
+    abstract override fun toString(): String
+}
+
+data class Data2(val field: String): Base(), AbstractAnyMembers
diff --git a/compiler/testData/diagnostics/tests/dataClasses/implementMethodsFromInterface.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/implementMethodsFromInterface.fir.kt
new file mode 100644
index 00000000000..be0e89007bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/implementMethodsFromInterface.fir.kt
@@ -0,0 +1,25 @@
+// KT-11306 ABSTRACT_MEMBER_NOT_IMPLEMENTED for data class should inheriting interfaces requiring equals(), hashCode(), or toString()
+
+interface Foo {
+    override fun equals(other: Any?): Boolean
+    override fun hashCode(): Int
+    override fun toString(): String
+}
+
+data class FooImpl(val num: Int) : Foo
+
+data class FooImplSome(val num: Int) : Foo {
+    override fun hashCode() = 42
+}
+
+data class FooImplAll(val num: Int) : Foo {
+    override fun equals(other: Any?) = false
+    override fun hashCode() = 42
+    override fun toString() = "OK"
+}
+
+
+data class WrongSignatures(val num: Int) : Foo {
+    override fun equals(other: WrongSignatures) = false
+    override fun hashCode(): Boolean = true
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasComponent1.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasComponent1.fir.kt
new file mode 100644
index 00000000000..7cb40548632
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasComponent1.fir.kt
@@ -0,0 +1,5 @@
+interface T {
+    fun component1(): Int
+}
+
+data class A(val x: Int) : T
diff --git a/compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasFinalComponent1.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasFinalComponent1.fir.kt
new file mode 100644
index 00000000000..107969b1faf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/implementTraitWhichHasFinalComponent1.fir.kt
@@ -0,0 +1,5 @@
+interface T {
+    final fun component1(): Int = 42
+}
+
+data class A(val x: Int) : T
diff --git a/compiler/testData/diagnostics/tests/dataClasses/innerDataClass.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/innerDataClass.fir.kt
new file mode 100644
index 00000000000..18c9b2307af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/innerDataClass.fir.kt
@@ -0,0 +1,3 @@
+class Outer {
+    inner data class Inner(val x: Int)
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/innerOuterDataClass.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/innerOuterDataClass.fir.kt
new file mode 100644
index 00000000000..496921194f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/innerOuterDataClass.fir.kt
@@ -0,0 +1 @@
+inner data class Outer(val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/multiDeclaration.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/multiDeclaration.fir.kt
new file mode 100644
index 00000000000..803873a0464
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/multiDeclaration.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+data class A(val x: Int, val y: String)
+
+fun foo(a: A) {
+    val (b, c) = a
+    checkSubtype<Int>(b)
+    checkSubtype<String>(c)
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/multiDeclarationFor.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/multiDeclarationFor.fir.kt
new file mode 100644
index 00000000000..ce7a01130e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/multiDeclarationFor.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+data class A(val x: Int, val y: String)
+
+fun foo(arr: Array<A>) {
+    for ((b, c) in arr) {
+        checkSubtype<Int>(b)
+        checkSubtype<String>(c)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/noConstructor.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/noConstructor.fir.kt
new file mode 100644
index 00000000000..ddaab4d82a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/noConstructor.fir.kt
@@ -0,0 +1,6 @@
+data class A
+
+fun foo(a: A) {
+    a.<!UNRESOLVED_REFERENCE!>component1<!>()
+    a.<!UNRESOLVED_REFERENCE!>component2<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/notADataClass.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/notADataClass.fir.kt
new file mode 100644
index 00000000000..2561937f3e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/notADataClass.fir.kt
@@ -0,0 +1,6 @@
+class A(val x: Int, val y: String)
+
+fun foo(a: A) {
+    a.<!UNRESOLVED_REFERENCE!>component1<!>()
+    a.<!UNRESOLVED_REFERENCE!>component2<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/oneValParam.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/oneValParam.fir.kt
new file mode 100644
index 00000000000..6b9054c630b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/oneValParam.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+data class A(val x: Int)
+
+fun foo(a: A) {
+    checkSubtype<Int>(a.component1())
+    a.<!UNRESOLVED_REFERENCE!>component2<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/repeatedProperties.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/repeatedProperties.fir.kt
new file mode 100644
index 00000000000..798f24affcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/repeatedProperties.fir.kt
@@ -0,0 +1,9 @@
+data class A1(val x: Int, val y: String, val x: Int) {
+    val z = ""
+}
+
+data class A2(val x: Int, val y: String) {
+    val x = ""
+}
+
+data class A3(val<!SYNTAX!><!> :Int, val<!SYNTAX!><!> : Int)
diff --git a/compiler/testData/diagnostics/tests/dataClasses/sealedDataClass.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/sealedDataClass.fir.kt
new file mode 100644
index 00000000000..8899146b396
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/sealedDataClass.fir.kt
@@ -0,0 +1,4 @@
+sealed data class My(val x: Int) {
+    object Your: My(1)
+    class His(y: Int): My(y)
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/strange.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/strange.fir.kt
new file mode 100644
index 00000000000..51a73b39b19
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/strange.fir.kt
@@ -0,0 +1,10 @@
+data enum class First(val x: Int) {
+    A(1),
+    B(2)
+}
+
+data object Second
+
+data interface Third
+
+data annotation class Fourth(val x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataClasses/twoValParams.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/twoValParams.fir.kt
new file mode 100644
index 00000000000..53228d514ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/twoValParams.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+data class A(val x: Int, val y: String)
+
+fun foo(a: A) {
+    checkSubtype<Int>(a.component1())
+    checkSubtype<String>(a.component2())
+}
diff --git a/compiler/testData/diagnostics/tests/dataClasses/twoVarParams.fir.kt b/compiler/testData/diagnostics/tests/dataClasses/twoVarParams.fir.kt
new file mode 100644
index 00000000000..d7d038aabc3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataClasses/twoVarParams.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+data class A(var x: Int, var y: String)
+
+fun foo(a: A) {
+    checkSubtype<Int>(a.component1())
+    checkSubtype<String>(a.component2())
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlow/CalleeExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/CalleeExpression.fir.kt
new file mode 100644
index 00000000000..7343419e835
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/CalleeExpression.fir.kt
@@ -0,0 +1,7 @@
+class C(val f : () -> Unit)
+
+fun test(e : Any) {
+    if (e is C) {
+        (e.f)()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlow/EmptyIf.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/EmptyIf.fir.kt
new file mode 100644
index 00000000000..4b3db89acdc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/EmptyIf.fir.kt
@@ -0,0 +1,24 @@
+// !CHECK_TYPE
+
+fun f1(s: String?) {
+    if (s!! == "");
+    checkSubtype<String>(s)
+}
+
+fun f2(s: Number?) {
+    if (s is Int);
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(s)
+    if (s as Int == 42);
+    checkSubtype<Int>(s)
+}
+
+fun f3(s: Number?) {
+    if (s is Int && s as Int == 42);
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(s)
+}
+
+fun f4(s: Int?) {
+    var u = if (s!! == 42);
+    if (u == Unit) u = if (s == 239);
+    return u
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/IsExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/IsExpression.fir.kt
new file mode 100644
index 00000000000..c97b7f0dab6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/IsExpression.fir.kt
@@ -0,0 +1,6 @@
+fun f(a: Boolean, b: Int) {}
+
+fun foo(a: Any) {
+    <!INAPPLICABLE_CANDIDATE!>f<!>(a is Int, a)
+    1 <!INAPPLICABLE_CANDIDATE!>+<!> a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/WhenSubject.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/WhenSubject.fir.kt
new file mode 100644
index 00000000000..3b8d12cc256
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/WhenSubject.fir.kt
@@ -0,0 +1,10 @@
+interface Expr
+class BinOp(val operator : String) : Expr
+
+fun test(e : Expr) {
+    if (e is BinOp) {
+        when (e.operator) {
+            else -> 0
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/assignment/assignToNewVal.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/assignment/assignToNewVal.fir.kt
new file mode 100644
index 00000000000..8db26209994
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/assignment/assignToNewVal.fir.kt
@@ -0,0 +1,10 @@
+fun test(a: Any?) {
+    if (a == null) return
+    a.hashCode()
+
+    val b = a
+    b.hashCode()
+
+    val c: Any? = a
+    c.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/assignment/kt6118.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/assignment/kt6118.fir.kt
new file mode 100644
index 00000000000..c16bb040bcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/assignment/kt6118.fir.kt
@@ -0,0 +1,16 @@
+// KT-6118 Redundant type cast can be not redundant?
+
+fun foo(o: Any) {
+    if (o is String) {
+        val s = o as String
+        s.length
+    }
+}
+
+fun foo1(o: Any) {
+    if (o is String) {
+        o.length
+        val s = o
+        s.length
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValIsCheck.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValIsCheck.fir.kt
new file mode 100644
index 00000000000..4e946147fe0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValIsCheck.fir.kt
@@ -0,0 +1,15 @@
+fun test(a: Any?, flag: Boolean, x: Any?) {
+    if (a !is String) return
+    a.length
+
+    val b: Any?
+
+    if (flag) {
+        b = a
+        b.length
+    }
+    else {
+        b = x
+        b.<!UNRESOLVED_REFERENCE!>length<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValNullability.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValNullability.fir.kt
new file mode 100644
index 00000000000..9becb2e132a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/assignment/uninitializedValNullability.fir.kt
@@ -0,0 +1,15 @@
+fun test(a: Any?, flag: Boolean, x: Any?) {
+    if (a == null) return
+    a.hashCode()
+
+    val b: Any?
+
+    if (flag) {
+        b = a
+        b.hashCode()
+    }
+    else {
+        b = x
+        b.hashCode()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/assignment/when.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/assignment/when.fir.kt
new file mode 100644
index 00000000000..04b1802c088
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/assignment/when.fir.kt
@@ -0,0 +1,12 @@
+fun test(a: Any?) {
+    when (a) {
+        is String -> {
+            val s = a
+            s.length
+        }
+        "" -> {
+            val s = a
+            s.hashCode()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassBase.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassBase.fir.kt
new file mode 100644
index 00000000000..5875f99ead4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassBase.fir.kt
@@ -0,0 +1,10 @@
+open class Base(x: String, y: Int)
+
+fun test(x: Any, y: Int?) {
+  if (x !is String) return
+  if (y == null) return
+
+  class Local: Base(x, y) {
+  }
+}
+
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDefaultParameters.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDefaultParameters.fir.kt
new file mode 100644
index 00000000000..8795f2753e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDefaultParameters.fir.kt
@@ -0,0 +1,8 @@
+fun test(x: Any) {
+  if (x !is String) return
+
+  class Local(s: String = x) {
+    fun foo(s: String = x): String = s
+  }
+}
+
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDelegatedProperties.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDelegatedProperties.fir.kt
new file mode 100644
index 00000000000..d3ad13805bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDelegatedProperties.fir.kt
@@ -0,0 +1,17 @@
+import kotlin.reflect.KProperty
+
+class Del {
+  operator fun getValue(_this: Any?, p: KProperty<*>): Int = 0
+}
+
+fun df(del: Del): Del = del
+
+
+fun test(del: Any?) {
+  if (del !is Del) return
+
+  class Local {
+    val delegatedVal by <!INAPPLICABLE_CANDIDATE!>df<!>(del)
+    val delegatedVal1: Int by <!INAPPLICABLE_CANDIDATE!>df<!>(del)
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDelegation.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDelegation.fir.kt
new file mode 100644
index 00000000000..8f89fe63db1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassDelegation.fir.kt
@@ -0,0 +1,11 @@
+interface D {
+  fun foo() {}
+}
+
+fun test(d: Any?) {
+  if (d !is D) return
+
+  class Local : D by d {
+  }
+}
+
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassFunctions.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassFunctions.fir.kt
new file mode 100644
index 00000000000..d71924e256b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassFunctions.fir.kt
@@ -0,0 +1,18 @@
+interface D {
+  fun foo(): String = ""
+}
+
+fun test(d: Any?) {
+  if (d !is D) return
+
+  class Local {
+    fun f() {
+      d.foo()
+    }
+
+    fun f1() = d.foo()
+
+    fun f2(): String = d.foo()
+  }
+}
+
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassInMemberOfLocalClass.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassInMemberOfLocalClass.fir.kt
new file mode 100644
index 00000000000..aecbf5dd376
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassInMemberOfLocalClass.fir.kt
@@ -0,0 +1,15 @@
+fun test(x: Any) {
+  if (x !is String) return
+
+  class LocalOuter {
+    fun foo(y: Any) {
+      if (y !is String) return
+      class Local {
+        init {
+          x.<!UNRESOLVED_REFERENCE!>length<!>
+          y.<!UNRESOLVED_REFERENCE!>length<!>
+        }
+      }
+    }
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassInitializer.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassInitializer.fir.kt
new file mode 100644
index 00000000000..361ec612108
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassInitializer.fir.kt
@@ -0,0 +1,16 @@
+// KT-338 Support.smartcasts in nested declarations
+
+fun f(a: Any?) {
+  if (a is B) {
+    class C : X(a) {
+      init {
+        a.<!UNRESOLVED_REFERENCE!>foo<!>()
+      }
+    }
+  }
+}
+
+interface B {
+  fun foo() {}
+}
+open class X(b: B)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassProperty.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassProperty.fir.kt
new file mode 100644
index 00000000000..9438e8363d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalClassProperty.fir.kt
@@ -0,0 +1,12 @@
+fun test(x: Any?) {
+  if (x !is String) return
+
+  class C {
+    val v = x.<!UNRESOLVED_REFERENCE!>length<!>
+
+    val vGet: Int
+      get() = x.<!UNRESOLVED_REFERENCE!>length<!>
+
+    val s: String = x
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalObject.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalObject.fir.kt
new file mode 100644
index 00000000000..e867333101a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalObject.fir.kt
@@ -0,0 +1,9 @@
+fun foo(x: Any?) {
+    if (x is String) {
+        object : Base(x) {
+            fun bar() = x.length
+        }
+    }
+}
+
+open class Base(s: String)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/LocalObjectDelegation.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/LocalObjectDelegation.fir.kt
new file mode 100644
index 00000000000..06755b3f374
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/LocalObjectDelegation.fir.kt
@@ -0,0 +1,15 @@
+// KT-2225 Object expression delegation parameter should be checked with data flow info
+
+interface A {
+    fun foo() : Int
+}
+
+class B : A {
+    override fun foo() = 10
+}
+fun foo(b: B?) : Int {
+    if (b == null) return 0
+    val o = object : A by b { //no info about b not null check
+    }
+    return o.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/NestedLocalClass.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/NestedLocalClass.fir.kt
new file mode 100644
index 00000000000..c94b2140ba6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/NestedLocalClass.fir.kt
@@ -0,0 +1,11 @@
+fun test(x: Any) {
+  if (x !is String) return
+
+  class LocalOuter {
+    inner class Local {
+      init {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+      }
+    }
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlow/local/kt2835.fir.kt b/compiler/testData/diagnostics/tests/dataFlow/local/kt2835.fir.kt
new file mode 100644
index 00000000000..ccd49b6834d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlow/local/kt2835.fir.kt
@@ -0,0 +1,8 @@
+open class X(val s: String)
+
+fun f(a: String?) {
+    if (a != null) {
+        object : X(a) { // Type mismatch: inferred type is kotlin.String? but kotlin.String was expected
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AndOr.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AndOr.fir.kt
new file mode 100644
index 00000000000..90e0bb04051
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AndOr.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    if (x != null && bar(x) == 0) bar(bar(x))
+    bar(x)
+    if (x == null || bar(x) == 0) bar(bar(x))
+    bar(x)
+    if (x is Int && bar(x)*bar(x) == bar(x)) bar(x)
+    bar(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayAccess.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayAccess.fir.kt
new file mode 100644
index 00000000000..cdf5521eaa1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayAccess.fir.kt
@@ -0,0 +1,13 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+    val a = Array<Int>(3, {0})
+
+    if (x != null) bar(a[x]) else bar(a[x])
+    bar(a[if (x == null) 0 else x])
+    bar(a[x])
+    
+    "123"[x];
+    if (x != null) "123"[x];
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayExpression.fir.kt
new file mode 100644
index 00000000000..21d5cba59d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayExpression.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+fun foo(arr: Array<out Number>): Int {
+    @Suppress("UNCHECKED_CAST")
+    val result = (arr as Array<Int>)[0]
+    checkSubtype<Array<Int>>(arr)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayGetSetConvention.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayGetSetConvention.fir.kt
new file mode 100644
index 00000000000..17176604658
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayGetSetConvention.fir.kt
@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+
+interface G {
+    operator fun get(x: Int, y: Int): Int = x + y
+    operator fun set(x: Int, y: Int, value: Int) {}
+}
+
+fun foo1(a: Int?, b: G) {
+    b[a!!, a!!] = a
+    checkSubtype<Int>(a)
+}
+
+fun foo2(a: Int?, b: G) {
+    b[0, a!!] = a
+    checkSubtype<Int>(a)
+}
+
+fun foo3(a: Int?, b: G) {
+    val r = b[a!!, a]
+    checkSubtype<Int>(a)
+    checkSubtype<Int>(r)
+}
+
+fun foo4(a: Int?, b: G) {
+    val r = b[0, a!!]
+    checkSubtype<Int>(a)
+    checkSubtype<Int>(r)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayIndices.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayIndices.fir.kt
new file mode 100644
index 00000000000..1fc7a3424b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ArrayIndices.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+fun foo1(a: Int?, b: Array<Array<Int>>) {
+    b[a!!][a!!] = a
+    checkSubtype<Int>(a)
+}
+
+fun foo2(a: Int?, b: Array<Array<Int>>) {
+    b[0][a!!] = a
+    checkSubtype<Int>(a)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Assignment.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Assignment.fir.kt
new file mode 100644
index 00000000000..6645e4728ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Assignment.fir.kt
@@ -0,0 +1,17 @@
+interface A
+interface B : A {
+    fun foo()
+}
+
+fun bar1(a: A) {
+    var b: B = a as B
+    a.foo()
+    b.foo()
+}
+
+fun id(b: B) = b
+fun bar2(a: A) {
+    var b: B = id(a as B)
+    a.foo()
+    b.foo()
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentInInitializer.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentInInitializer.fir.kt
new file mode 100644
index 00000000000..dbe7546d770
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentInInitializer.fir.kt
@@ -0,0 +1,21 @@
+// KT-2825  DataFlowInfo is not retained after assignment
+
+interface A
+
+interface B : A {
+    fun foo()
+}
+
+fun baz(b: B) = b
+
+fun bar1(a: A) {
+    val b = a as B
+    a.foo()
+    b.foo()
+}
+
+fun bar2(a: A) {
+    val b = baz(a as B)
+    a.foo()
+    b.foo()
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentOperation.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentOperation.fir.kt
new file mode 100644
index 00000000000..dc1adc8f13f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentOperation.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+fun bar1(x: Number, y: Int) {
+    var yy = y
+    yy += x as Int
+    checkSubtype<Int>(x)
+}
+
+fun bar2(x: Number) {
+    <!UNRESOLVED_REFERENCE, VARIABLE_EXPECTED!>y<!> += x as Int
+    checkSubtype<Int>(x)
+}
+
+fun bar3(x: Number, y: Array<Int>) {
+    y[0] += x as Int
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentToArrayElement.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentToArrayElement.fir.kt
new file mode 100644
index 00000000000..97b08c9bd7d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/AssignmentToArrayElement.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+fun arrayAccessRHS(a: Int?, b: Array<Int>) {
+    b[0] = a!!
+    checkSubtype<Int>(a)
+}
+
+fun arrayAccessLHS(a: Int?, b: Array<Int>) {
+    b[a!!] = a
+    checkSubtype<Int>(a)
+}
+
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpression.fir.kt
new file mode 100644
index 00000000000..1b8fe6d3ec4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpression.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    bar(1 + (if (x == null) 0 else x))
+    bar(if (x == null) x else x)
+    if (x != null) bar(x + x/(x-x*x))
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionBooleanOperations.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionBooleanOperations.fir.kt
new file mode 100644
index 00000000000..6dcd58c1a3d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionBooleanOperations.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+
+fun foo1(x: Number, cond: Boolean): Boolean {
+    val result = cond && ((x as Int) == 42)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(x)
+    return result
+}
+
+fun foo2(x: Number, cond: Boolean): Boolean {
+    val result = ((x as Int) == 42) && cond
+    checkSubtype<Int>(x)
+    return result
+}
+
+fun foo3(x: Number, cond: Boolean): Boolean {
+    val result = cond || ((x as Int) == 42)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(x)
+    return result
+}
+
+fun foo4(x: Number, cond: Boolean): Boolean {
+    val result = ((x as Int) == 42) || cond
+    checkSubtype<Int>(x)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionCompareToConvention.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionCompareToConvention.fir.kt
new file mode 100644
index 00000000000..2a8e9a02aa4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionCompareToConvention.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+interface A
+
+interface B : A
+operator fun B.compareTo(b: B) = if (this == b) 0 else 1
+
+fun foo(a: A): Boolean {
+    val result = (a as B) < a
+    checkSubtype<B>(a)
+    return result
+}
+
+fun bar(a: A, b: B): Boolean {
+    val result = b < (a as B)
+    checkSubtype<B>(a)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionContainsConvention.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionContainsConvention.fir.kt
new file mode 100644
index 00000000000..53c7b299e76
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionContainsConvention.fir.kt
@@ -0,0 +1,7 @@
+// !CHECK_TYPE
+
+fun foo(x: Number): Boolean {
+    val result = (x as Int) in 1..5
+    checkSubtype<Int>(x)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionElvis.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionElvis.fir.kt
new file mode 100644
index 00000000000..395d4b3ded5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionElvis.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+fun foo(x: Int?): Int = x!!
+
+fun elvis(x: Number?): Int {
+    val result = (x as Int?) ?: foo(x)
+    checkSubtype<Int?>(x)
+    return result
+}
+
+
+fun elvisWithRHSTypeInfo(x: Number?): Any? {
+    val result = x ?: x!!
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int?>(x)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionEqualsConvention.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionEqualsConvention.fir.kt
new file mode 100644
index 00000000000..7c49c13700b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionEqualsConvention.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+interface A
+interface B : A
+
+fun foo1(a: A, b: B): Boolean {
+    val result = (a as B) == b
+    checkSubtype<B>(a)
+    return result
+}
+
+fun foo2(a: A, b: B): Boolean {
+    val result = b == (a as B)
+    checkSubtype<B>(a)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionIdentifier.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionIdentifier.fir.kt
new file mode 100644
index 00000000000..05a276ef07e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionIdentifier.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+infix fun Int.compareTo(o: Int) = 0
+
+fun foo(a: Number): Int {
+    val result = (a as Int) compareTo a
+    checkSubtype<Int>(a)
+    return result
+}
+
+fun bar(a: Number): Int {
+    val result = 42 compareTo (a as Int)
+    checkSubtype<Int>(a)
+    return result
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionPlusConvention.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionPlusConvention.fir.kt
new file mode 100644
index 00000000000..4ba75f34ed8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionPlusConvention.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+interface A
+
+interface B : A
+operator fun B.plus(b: B) = if (this == b) b else this
+
+fun foo(a: A): B {
+    val result = (a as B) + a
+    checkSubtype<B>(a)
+    return result
+}
+
+fun bar(a: A, b: B): B {
+    val result = b + (a as B)
+    checkSubtype<B>(a)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Condition.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Condition.fir.kt
new file mode 100644
index 00000000000..b3fad0f71e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Condition.fir.kt
@@ -0,0 +1,7 @@
+// !CHECK_TYPE
+
+fun foo(x: Int?): Boolean {
+    val result = ((x!! == 0) && (checkSubtype<Int>(x) == 0))
+    checkSubtype<Int>(x)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ContinueOuterLoop.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ContinueOuterLoop.fir.kt
new file mode 100644
index 00000000000..4f0be07c6ef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ContinueOuterLoop.fir.kt
@@ -0,0 +1,34 @@
+// !CHECK_TYPE
+
+fun whileLoop(x: Int?) {
+    outer@ while (x != 0) {
+        while (x != 1) {
+            if (x == 2) continue@outer
+        }
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
+
+fun doWhileLoop(x: Int?) {
+    outer@ while (x != 0) {
+        do {
+            if (x == 2) continue@outer
+        } while (x == null)
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
+
+fun whileLoopContinueInnerOuter(x: Int?) {
+    outer@ while (x != 0) {
+        inner@ while (x != 1) {
+            while (x != 2) {
+                if (x == 3) continue@inner
+            }
+            checkSubtype<Int>(x)
+        }
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DeepIf.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DeepIf.fir.kt
new file mode 100644
index 00000000000..2e9264619c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DeepIf.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+fun bar(x: Int) = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    if (x != null) {
+        bar(x)
+        if (x != null) {
+            bar(x)
+            if (1 < 2) bar(x)
+            if (1 > 2) bar(x)
+        }
+        if (x == null) {
+            bar(x)
+        }
+        if (x == null) bar(x) else bar(x)
+        bar(bar(x))
+    } else if (x == null) {
+        bar(x)
+        if (x != null) {
+            bar(x)
+            if (x == null) bar(x)
+            if (x == null) bar(x) else bar(x)
+            bar(bar(x) + bar(x))
+        } else if (x == null) {
+            bar(x)
+        }
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DoWhile.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DoWhile.fir.kt
new file mode 100644
index 00000000000..0bbb351fb40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DoWhile.fir.kt
@@ -0,0 +1,16 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    do {
+        bar(x)
+    } while (x == null)
+    bar(x)
+    
+    val y: Int? = null
+    do {
+        bar(y)
+    } while (y != null)
+    bar(y)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DoWhileCondition.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DoWhileCondition.fir.kt
new file mode 100644
index 00000000000..6013fd34399
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/DoWhileCondition.fir.kt
@@ -0,0 +1,20 @@
+// !CHECK_TYPE
+
+fun simpleDoWhile(x: Int?, y0: Int) {
+    var y = y0
+    do {
+        checkSubtype<Int?>(x)
+        y++
+    } while (x!! == y)
+    checkSubtype<Int>(x)
+}
+
+fun doWhileWithBreak(x: Int?, y0: Int) {
+    var y = y0
+    do {
+        checkSubtype<Int?>(x)
+        y++
+        if (y > 0) break
+    } while (x!! == y)
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Elvis.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Elvis.fir.kt
new file mode 100644
index 00000000000..02bcd2bcdc6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Elvis.fir.kt
@@ -0,0 +1,9 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    bar(x ?: 0)
+    if (x != null) bar(x ?: x)
+    bar(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ExclExcl.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ExclExcl.fir.kt
new file mode 100644
index 00000000000..e7b403026f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ExclExcl.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+fun bar(x: Int) = x + 1
+
+fun f1(x: Int?) {
+    bar(x)
+    if (x != null) bar(x!!)
+    if (x == null) bar(x!!)
+}
+
+fun f2(x: Int?) {    
+    if (x != null) else x!!
+}
+
+fun f3(x: Int?) {    
+    if (x != null) bar(x!!) else x!!
+}
+    
+fun f4(x: Int?) {    
+    if (x == null) x!! else bar(x!!)
+}
+
+fun f5(x: Int?) {    
+    if (x == null) else bar(x!!)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/For.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/For.fir.kt
new file mode 100644
index 00000000000..28b3d130b89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/For.fir.kt
@@ -0,0 +1,22 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+    val a = Array<Int>(3, {0})
+
+    for (p in a) {
+        bar(x)
+        if (x == null) continue
+        bar(x)
+        for (q in a) {
+            bar(x)
+            if (x == null) bar(x)
+        }
+    }
+
+    for (p in a) {
+        bar(x)
+        if (x == null) break
+        bar(x)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ForLoopRange.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ForLoopRange.fir.kt
new file mode 100644
index 00000000000..9b843e160aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ForLoopRange.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+fun foo(arr: Array<Int>?) {
+    for (x in arr!!) {
+        checkSubtype<Array<Int>>(arr)
+    }
+    checkSubtype<Array<Int>>(arr)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/FunctionLiteral.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/FunctionLiteral.fir.kt
new file mode 100644
index 00000000000..1fc2dfb71ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/FunctionLiteral.fir.kt
@@ -0,0 +1,9 @@
+fun bar(x: Int) = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    fun baz() = bar(x)
+    fun quux() = if (x != null) bar(x) else baz()
+    fun quuux() = bar(if (x == null) 0 else x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfStatement.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfStatement.fir.kt
new file mode 100644
index 00000000000..ef88daf14ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfStatement.fir.kt
@@ -0,0 +1,31 @@
+// !CHECK_TYPE
+
+fun ifThen(x: Int?) {
+    if (x!! == 0) {
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
+
+fun ifElse(x: Int?) {
+    if (x!! == 0) else {
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
+
+fun ifThenElse(x: Int?) {
+    if (x!! == 0) {
+        checkSubtype<Int>(x)
+    } else {
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
+
+fun ifIs(x: Int?, cond: Boolean) {
+    if ((x is Int) == cond) {
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfThenElse.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfThenElse.fir.kt
new file mode 100644
index 00000000000..be811fb9c40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfThenElse.fir.kt
@@ -0,0 +1,30 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    bar(if (x == null) 0 else x)
+
+    if (x == null) {
+        bar(x)
+        return
+    } else {
+        bar(x)
+    }
+    bar(x)
+
+    val y: Int? = null
+    if (y is Int) {
+        bar(y)
+    } else {
+        bar(y)
+        return
+    }
+    bar(y)
+
+    val z: Int? = null
+    if (z != null) bar(z)
+    bar(z)
+    bar(z!!)
+    if (z != null) bar(z!!)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfThenElseBothInvalid.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfThenElseBothInvalid.fir.kt
new file mode 100644
index 00000000000..94aaf079517
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IfThenElseBothInvalid.fir.kt
@@ -0,0 +1,16 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    bar(x)
+    if (x != 2) {
+        if (x == null) return
+        2<!AMBIGUITY!>+<!><!SYNTAX!><!>
+    }
+    else {
+        if (x == null) return
+        2<!AMBIGUITY!>+<!><!SYNTAX!><!>
+    }
+    bar(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IsExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IsExpression.fir.kt
new file mode 100644
index 00000000000..565ded5a2b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/IsExpression.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+fun foo(x: Number) {
+    if ((x as Int) is Int) {
+        checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ManyIfs.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ManyIfs.fir.kt
new file mode 100644
index 00000000000..e74aec692cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ManyIfs.fir.kt
@@ -0,0 +1,32 @@
+// !CHECK_TYPE
+
+fun noUselessDataFlowInfoCreation(x: Number) {
+    if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) {
+    if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) {
+    if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) {
+    if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) {
+    if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) { if (x is Int) {
+    } } } } } } } } } } } } } } } } } } } } } } } } }
+}
+
+fun dataFlowInfoAnd(a: Array<Number>) {
+    if (a[0] is Int) { if (a[1] is Int) { if (a[2] is Int) { if (a[3] is Int) { if (a[4] is Int) {
+    if (a[5] is Int) { if (a[6] is Int) { if (a[7] is Int) { if (a[8] is Int) { if (a[9] is Int) {
+    if (a[10] is Int) { if (a[11] is Int) { if (a[12] is Int) { if (a[13] is Int) { if (a[14] is Int) {
+    if (a[15] is Int) { if (a[16] is Int) { if (a[17] is Int) { if (a[18] is Int) { if (a[19] is Int) {
+    if (a[20] is Int) { if (a[21] is Int) { if (a[22] is Int) { if (a[23] is Int) { if (a[24] is Int) {
+    if (a[25] is Int) { if (a[26] is Int) { if (a[27] is Int) { if (a[28] is Int) { if (a[29] is Int) {
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(a[0])
+    } } } } } } } } } } } } } } } } } } } } } } } } } } } } } }
+}
+
+fun dataFlowInfoOr(a: Array<Number>) {
+    if (a[0] is Int || a[1] is Int || a[2] is Int || a[3] is Int || a[4] is Int || a[5] is Int || a[6] is Int || a[7] is Int || a[8] is Int || a[9] is Int || 
+        a[10] is Int || a[11] is Int || a[12] is Int || a[13] is Int || a[14] is Int || a[15] is Int || a[16] is Int || a[17] is Int || a[18] is Int || a[19] is Int || 
+        a[20] is Int || a[21] is Int || a[22] is Int || a[23] is Int || a[24] is Int || a[25] is Int || a[26] is Int || a[27] is Int || a[28] is Int || a[29] is Int || 
+        a[30] is Int || a[31] is Int || a[32] is Int || a[33] is Int || a[34] is Int || a[35] is Int || a[36] is Int || a[37] is Int || a[38] is Int || a[39] is Int || 
+        a[40] is Int || a[41] is Int || a[42] is Int || a[43] is Int || a[44] is Int || a[45] is Int || a[46] is Int || a[47] is Int || a[48] is Int || a[49] is Int || 
+        a[50] is Int || a[51] is Int || a[52] is Int || a[53] is Int || a[54] is Int || a[55] is Int || a[56] is Int || a[57] is Int || a[58] is Int || a[59] is Int) {
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(a[0])
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/MultiDeclaration.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/MultiDeclaration.fir.kt
new file mode 100644
index 00000000000..9395107e292
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/MultiDeclaration.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+operator fun Int.component1() = "a"
+
+fun foo(a: Number) {
+    val (x) = a as Int
+    checkSubtype<Int>(a)
+    checkSubtype<String>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ObjectExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ObjectExpression.fir.kt
new file mode 100644
index 00000000000..ff96ed65c89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ObjectExpression.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    val a = object {
+        fun baz() = bar(if (x == null) 0 else x)
+        fun quux(): Int = if (x == null) x else x
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/QualifiedExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/QualifiedExpression.fir.kt
new file mode 100644
index 00000000000..81eddacff27
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/QualifiedExpression.fir.kt
@@ -0,0 +1,13 @@
+fun baz(x: Int): Int = x + 1
+
+class A {
+    fun bar(x: Int) = baz(x)
+}
+
+fun foo() {
+    val x: Int? = null
+
+    A().bar(x)
+    if (x == null) return
+    A().bar(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Return.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Return.fir.kt
new file mode 100644
index 00000000000..7165f3c6a56
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Return.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+fun bar(x: Int): Int = x + 1
+
+fun foo(): Int {
+    val x: Int? = null
+
+    bar(x)
+    if (x != null) return x
+    
+    val y: Int? = null
+    if (y == null) return if (y != null) y else y
+    
+    val z: Int? = null
+    if (z != null) return if (z == null) z else z
+    
+    return z
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/StringTemplate.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/StringTemplate.fir.kt
new file mode 100644
index 00000000000..991605891da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/StringTemplate.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+fun foo(x: Number, y: String?): String {
+    val result = "abcde $x ${x as Int} ${y!!} $x $y"
+    checkSubtype<Int>(x)
+    checkSubtype<String>(y)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ThisSuper.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ThisSuper.fir.kt
new file mode 100644
index 00000000000..1d4dedb550e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/ThisSuper.fir.kt
@@ -0,0 +1,21 @@
+open class Base {
+    fun bar(x: Int): Int = x + 1
+}
+
+class Derived : Base() {
+    fun baz(x: Int): Int = x + 1
+
+    fun foo() {
+        val x: Int? = null
+
+        super.bar(x)
+        this.baz(x)
+        if (x == null) return
+        super.bar(x)
+        this.baz(x)
+
+        val y: Int? = null
+        if (y != null) super.bar(this.baz(y))
+        else this.baz(super.bar(y))
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Throw.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Throw.fir.kt
new file mode 100644
index 00000000000..ffe940b64d7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/Throw.fir.kt
@@ -0,0 +1,9 @@
+fun bar(x: Int): RuntimeException = RuntimeException(x.toString())
+
+fun foo() {
+    val x: Int? = null
+
+    if (x == null) throw bar(x)
+    throw bar(x)
+    throw bar(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/TryCatch.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/TryCatch.fir.kt
new file mode 100644
index 00000000000..48bcd7fe2aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/TryCatch.fir.kt
@@ -0,0 +1,15 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+    
+    bar(x)
+    if (x == null) return
+    try {
+        bar(x)
+    }
+    catch (e: Exception) {
+        bar(x)
+    }
+    bar(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/TryFinally.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/TryFinally.fir.kt
new file mode 100644
index 00000000000..7bf4b2deb91
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/TryFinally.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+
+fun tryFinally(x: Int?) {
+    try {
+    } finally {
+        x!!
+    }
+    checkSubtype<Int>(x)
+}
+
+fun tryCatchFinally(x: Int?) {
+    try {
+        x!!
+    } catch (e: Exception) {
+        x!!
+    } finally {
+        checkSubtype<Int>(x)
+        x!!
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/UnaryExpression.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/UnaryExpression.fir.kt
new file mode 100644
index 00000000000..168fea3ca59
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/UnaryExpression.fir.kt
@@ -0,0 +1,14 @@
+fun bar(x: Int): Int = x + 1
+fun baz(b: Boolean): Boolean = !b
+
+fun foo() {
+    val x: Int? = null
+
+    bar(<!INAPPLICABLE_CANDIDATE!>-<!>x)
+    if (x != null) bar(-x)
+    bar(<!INAPPLICABLE_CANDIDATE!>-<!>x)
+
+    val b: Boolean? = null
+    baz(<!INAPPLICABLE_CANDIDATE!>!<!>b)
+    if (b != null) baz(!b)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/When.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/When.fir.kt
new file mode 100644
index 00000000000..5582e7b2346
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/When.fir.kt
@@ -0,0 +1,18 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+
+    if (x != null) {
+        when (x) {
+            0 -> bar(x)
+            else -> {}
+        }
+    }
+
+    when (x) {
+        0 -> { if (x == null) return }
+        else -> { if (x == null) return }
+    }
+    bar(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryAs.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryAs.fir.kt
new file mode 100644
index 00000000000..cd33062c286
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryAs.fir.kt
@@ -0,0 +1,26 @@
+// !CHECK_TYPE
+
+fun foo(x: Number, y: Int) {
+    when (x) {
+        x as Int -> checkSubtype<Int>(x)
+        y -> {}
+        else -> {}
+    }
+    checkSubtype<Int>(x)
+}
+
+fun bar(x: Number) {
+    when (x) {
+        x as Int -> checkSubtype<Int>(x)
+        else -> {}
+    }
+    checkSubtype<Int>(x)
+}
+
+fun whenWithoutSubject(x: Number) {
+    when {
+        (x as Int) == 42 -> checkSubtype<Int>(x)
+        else -> {}
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryIs.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryIs.fir.kt
new file mode 100644
index 00000000000..1b923955510
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenEntryIs.fir.kt
@@ -0,0 +1,26 @@
+// !CHECK_TYPE
+
+fun foo(x: Number, y: Int) {
+    when (x) {
+        is Int -> checkSubtype<Int>(x)
+        y -> {}
+        else -> {}
+    }
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(x)
+}
+
+fun bar(x: Number) {
+    when (x) {
+        is Int -> checkSubtype<Int>(x)
+        else -> {}
+    }
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(x)
+}
+
+fun whenWithoutSubject(x: Number) {
+    when {
+        (x is Int) -> checkSubtype<Int>(x)
+        else -> {}
+    }
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenIn.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenIn.fir.kt
new file mode 100644
index 00000000000..f287d76b098
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenIn.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+fun foo(x: Int, list: List<Int>?) {
+    when (x) {
+        in list!! -> checkSubtype<List<Int>>(list)
+        else -> {}
+    }
+}
+
+fun whenWithoutSubject(x: Int, list: List<Int>?) {
+    when {
+        x in list!! -> checkSubtype<List<Int>>(list)
+        else -> {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenSubject.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenSubject.fir.kt
new file mode 100644
index 00000000000..40cf4b1af2c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhenSubject.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+fun foo(x: Number) {
+    when (x as Int) {
+        else -> checkSubtype<Int>(x)
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/While.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/While.fir.kt
new file mode 100644
index 00000000000..1a78dde9378
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/While.fir.kt
@@ -0,0 +1,22 @@
+fun bar(x: Int): Int = x + 1
+
+fun foo() {
+    val x: Int? = null
+    while (x == null) {
+        bar(x)
+    }
+    bar(x)
+    
+    val y: Int? = null
+    while (y != null) {
+        bar(y)
+    }
+    bar(y)
+    
+    val z: Int? = null
+    while (z == null) {
+        bar(z)
+        break
+    }
+    bar(z)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhileCondition.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhileCondition.fir.kt
new file mode 100644
index 00000000000..43948d78597
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/WhileCondition.fir.kt
@@ -0,0 +1,26 @@
+// !CHECK_TYPE
+
+fun simpleWhile(x: Int?, y0: Int) {
+    var y = y0
+    while (x!! == y) {
+        checkSubtype<Int>(x)
+        y++
+    }
+    checkSubtype<Int>(x)
+}
+
+fun whileWithBreak(x: Int?, y0: Int) {
+    var y = y0
+    while (x!! == y) {
+        checkSubtype<Int>(x)
+        break
+    }
+    checkSubtype<Int>(x)
+}
+
+fun whileWithNoCondition(x: Int?) {
+    while (<!SYNTAX!><!>) {
+        x!!
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt4332WhenBranches.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt4332WhenBranches.fir.kt
new file mode 100644
index 00000000000..37d2f02045a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt4332WhenBranches.fir.kt
@@ -0,0 +1,9 @@
+//KT-4332 when/smartcast underperforms
+
+fun testWhen(t: String?, x: String?): Int {
+    return when {
+        t == null -> 0
+        x == null -> t.length // Wrong error report here. t can be inferred as not-null. (And it actually does if you replace when with if/else if)
+        else -> (t + x).length
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5155WhenBranches.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5155WhenBranches.fir.kt
new file mode 100644
index 00000000000..69c9c86f1d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5155WhenBranches.fir.kt
@@ -0,0 +1,11 @@
+//KT-5155 Auto-casts do not work with when
+
+fun foo(s: String?) {
+    when {
+        s == null -> 1
+        s.foo() -> 2
+        else -> 3
+    }
+}
+
+fun String.foo() = true
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5182WhenBranches.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5182WhenBranches.fir.kt
new file mode 100644
index 00000000000..fdceaaa2d8e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/kt5182WhenBranches.fir.kt
@@ -0,0 +1,13 @@
+//KT-5182 Data flow info is lost for 'when' branches
+
+open class A
+
+class B: A() {
+    fun foo() = 1
+}
+
+fun foo(a: A) = when {
+    a !is B -> 2
+    true -> a.foo() //'foo' is unresolved, smart cast doesn't work
+    else -> a.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/smartcasts/SmartcastAmbiguitites.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/smartcasts/SmartcastAmbiguitites.fir.kt
new file mode 100644
index 00000000000..bd99e969b39
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/smartcasts/SmartcastAmbiguitites.fir.kt
@@ -0,0 +1,16 @@
+interface B {
+  fun bar() {}
+}
+
+class C() {
+  fun bar() {
+  }
+}
+
+fun test(a : Any?) {
+  if (a is B) {
+      if (a is C) {
+          a.<!AMBIGUITY!>bar<!>();
+      }
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/smartcasts/SmartcastsForStableIdentifiers.fir.kt b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/smartcasts/SmartcastsForStableIdentifiers.fir.kt
new file mode 100644
index 00000000000..738b370eb10
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dataFlowInfoTraversal/smartcasts/SmartcastsForStableIdentifiers.fir.kt
@@ -0,0 +1,86 @@
+// FILE: a.kt
+package example.ns
+
+val y : Any? = 2
+
+// FILE: b.kt
+package example
+
+import example.ns.y
+
+object Obj {
+    val y : Any? = 2
+}
+
+class AClass() {
+    companion object {
+        val y : Any? = 2
+    }
+}
+
+val x : Any? = 1
+
+fun Any?.vars(a: Any?) : Int {
+    var b: Int = 0
+    if (example.ns.y is Int) {
+        b = y
+    }
+    if (example.ns.y is Int) {
+        b = example.ns.y
+    }
+    if (Obj.y is Int) {
+        b = Obj.y
+    }
+    if (example.Obj.y is Int) {
+        b = Obj.y
+    }
+    if (AClass.y is Int) {
+        b = AClass.y
+    }
+    if (example.AClass.y is Int) {
+        b = AClass.y
+    }
+    if (x is Int) {
+        b = x
+    }
+    if (example.x is Int) {
+        b = x
+    }
+    if (example.x is Int) {
+        b = example.x
+    }
+    return 1
+}
+
+fun Any?.foo() : Int {
+    if (this is Int)
+      return this
+    if (this@foo is Int)
+      return this
+    if (this@foo is Int)
+      return this@foo
+    if (this is Int)
+      return this@foo
+    return 1
+}
+
+
+interface T {}
+
+open class C {
+    fun foo() {
+       var t : T? = null
+       if (this is T) {
+          t = this
+       }
+       if (this is T) {
+          t = this@C
+       }
+       if (this@C is T) {
+          t = this
+       }
+       if (this@C is T) {
+          t = this@C
+       }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/ComponentFunctionReturnTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/ComponentFunctionReturnTypeMismatch.fir.kt
new file mode 100644
index 00000000000..e8bc3635afa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/ComponentFunctionReturnTypeMismatch.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+class A {
+    operator fun component1() : Int = 1
+    operator fun component2() : Int = 2
+}
+
+fun a(aa : A) {
+    val (a: String, b1: String) = aa
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.fir.kt
new file mode 100644
index 00000000000..c46a729de20
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/ConflictingAndRedundantProjections.fir.kt
@@ -0,0 +1,20 @@
+class In<in T>
+class Out<out T>
+class Inv<T>
+class X
+
+fun f1(p: In<in X>) {}
+fun f2(p: In<out X>) {}
+fun f3(p: In<X>) {}
+
+fun f4(p: Out<out X>) {}
+fun f5(p: Out<in X>) {}
+fun f6(p: Out<X>) {}
+
+fun f6(p: Inv<X>) {}
+fun f7(p: Inv<in X>) {}
+fun f8(p: Inv<out X>) {}
+
+fun f9(p: In<*>) {}
+fun f10(p: Out<*>) {}
+fun f11(p: Inv<*>) {}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/DataFlowInMultiDeclInFor.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/DataFlowInMultiDeclInFor.fir.kt
new file mode 100644
index 00000000000..f84f4933f5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/DataFlowInMultiDeclInFor.fir.kt
@@ -0,0 +1,15 @@
+// KT-2667 Support multi-declarations in for-loops in control flow analysis
+package d
+
+class A {
+    operator fun component1() = 1
+    operator fun component2() = 2
+    operator fun component3() = 3
+}
+
+fun foo(list: List<A>) {
+    for (var (c1, c2, c3) in list) {
+        c1 = 1
+        c3 + 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/DataFlowInfoInMultiDecl.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/DataFlowInfoInMultiDecl.fir.kt
new file mode 100644
index 00000000000..59fec99c251
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/DataFlowInfoInMultiDecl.fir.kt
@@ -0,0 +1,14 @@
+class A {
+    operator fun component1() : Int = 1
+    operator fun component2() : Int = 2
+}
+
+fun a(aa : A?, b : Any) {
+    if (aa != null) {
+        val (a1, b1) = aa;
+    }
+
+    if (b is A) {
+        val (a1, b1) = b;
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/FunctionWithMissingNames.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/FunctionWithMissingNames.fir.kt
new file mode 100644
index 00000000000..35f770556d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/FunctionWithMissingNames.fir.kt
@@ -0,0 +1,26 @@
+@Target(AnnotationTarget.TYPE, AnnotationTarget.FUNCTION)
+annotation class a
+interface A
+interface B
+
+fun () {}
+fun A.() {}
+
+@a fun () {}
+fun @a A.() {}
+
+class Outer {
+    fun () {}
+    fun B.() {}
+
+    @a fun () {}
+    fun @a A.() {}
+}
+
+fun outerFun() {
+    fun () {}
+    fun B.() {}
+
+    @a fun () {}
+    fun @a A.() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/LocalVariableWithNoTypeInformation.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/LocalVariableWithNoTypeInformation.fir.kt
new file mode 100644
index 00000000000..12509208784
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/LocalVariableWithNoTypeInformation.fir.kt
@@ -0,0 +1,3 @@
+fun test() {
+    val a
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/MultiDeclarationErrors.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/MultiDeclarationErrors.fir.kt
new file mode 100644
index 00000000000..b6c3498867d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/MultiDeclarationErrors.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+package a
+
+class MyClass {
+    fun component1(i: Int) {}
+}
+
+class MyClass2 {}
+
+fun MyClass2.component1() = 1.2
+fun MyClass2.component1() = 1.3
+
+fun test(mc1: MyClass, mc2: MyClass2) {
+    val (<!INAPPLICABLE_CANDIDATE!>a<!>, <!UNRESOLVED_REFERENCE!>b<!>) = mc1
+    val (c) = mc2
+
+    //a,b,c are error types
+    use(a, b, c)
+}
+
+fun use(vararg a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/RedeclarationsInMultiDecl.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/RedeclarationsInMultiDecl.fir.kt
new file mode 100644
index 00000000000..0c7b4aad47f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/RedeclarationsInMultiDecl.fir.kt
@@ -0,0 +1,15 @@
+class A {
+    operator fun component1() : Int = 1
+    operator fun component2() : Int = 2
+}
+
+fun a() {
+    val (a, a) = A()
+    val (x, y) = A();
+    val b = 1
+    use(b)
+    val (b, y) = A();
+}
+
+
+fun use(a: Any): Any = a
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/ScalaLikeNamedFun.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/ScalaLikeNamedFun.fir.kt
new file mode 100644
index 00000000000..1277796ace5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/ScalaLikeNamedFun.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// KT-5068 Add special error for scala-like syntax 'fun foo(): Int = { 1 }'
+
+fun test1(): Int = { return 1 }
+fun test2(): Int = { 1 }
+val test3: () -> Int = fun (): Int = { return 1 }
+val test4: () -> Int = fun (): Int = { 1 }
+fun test5(): Int { return { 1 } }
+fun test6(): Int = fun (): Int = 1
+
+fun outer() {
+    fun test1(): Int = { return 1 }
+    fun test2(): Int = { 1 }
+    val test3: () -> Int = fun (): Int = { return 1 }
+    val test4: () -> Int = fun (): Int = { 1 }
+    fun test5(): Int { return { 1 } }
+    fun test6(): Int = fun (): Int = 1
+}
+
+class Outer {
+    fun test1(): Int = { return 1 }
+    fun test2(): Int = { 1 }
+    val test3: () -> Int = fun (): Int = { return 1 }
+    val test4: () -> Int = fun (): Int = { 1 }
+    fun test5(): Int { return { 1 } }
+    fun test6(): Int = fun (): Int = 1
+
+    class Nested {
+        fun test1(): Int = { return 1 }
+        fun test2(): Int = { 1 }
+        val test3: () -> Int = fun (): Int = { return 1 }
+        val test4: () -> Int = fun (): Int = { 1 }
+        fun test5(): Int { return { 1 } }
+        fun test6(): Int = fun (): Int = 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/VarianceOnFunctionAndPropertyTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/VarianceOnFunctionAndPropertyTypeParameters.fir.kt
new file mode 100644
index 00000000000..504ca188548
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/VarianceOnFunctionAndPropertyTypeParameters.fir.kt
@@ -0,0 +1,17 @@
+fun <in T> f() {
+    
+}
+
+fun <out T> g() {
+
+}
+
+fun <out T, in X, Y> h() {
+
+}
+
+val <out T> T.x: Int
+    get() = 1
+
+val <in T> T.y: Int
+    get() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/ambiguousObjectExpressionType.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/ambiguousObjectExpressionType.fir.kt
new file mode 100644
index 00000000000..28f01fe3d3c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/ambiguousObjectExpressionType.fir.kt
@@ -0,0 +1,120 @@
+interface MyTrait {
+    fun f1() {}
+}
+
+open class MyClass {
+    fun f2() {}
+}
+
+
+class Foo {
+
+    private val privateProperty = object : MyClass(), MyTrait {}
+
+    init {
+        privateProperty.f1()
+        privateProperty.f2()
+    }
+
+    protected val protectedProperty = object : MyClass(), MyTrait {}
+
+    val internalProperty = object : MyClass(), MyTrait {}
+
+    internal val internal2Property = object : MyClass(), MyTrait {}
+
+    public val publicProperty = object : MyClass(), MyTrait {}
+
+    val propertyWithGetter
+    get() = object: MyClass(), MyTrait {}
+
+
+    private fun privateFunction() = object : MyClass(), MyTrait {}
+
+    init {
+        privateFunction().f1()
+        privateFunction().f2()
+    }
+
+    protected fun protectedFunction() = object : MyClass(), MyTrait {}
+
+    fun internalFunction() = object : MyClass(), MyTrait {}
+
+    internal fun internal2Function() = object : MyClass(), MyTrait {}
+
+    public fun publicFunction() = object : MyClass(), MyTrait {}
+
+
+
+    class FooInner {
+        private val privatePropertyInner = object : MyClass(), MyTrait {}
+
+        init {
+            privatePropertyInner.f1()
+            privatePropertyInner.f2()
+        }
+
+        protected val protectedProperty = object : MyClass(), MyTrait {}
+
+        val internalProperty = object : MyClass(), MyTrait {}
+
+        internal val internal2Property = object : MyClass(), MyTrait {}
+
+        public val publicProperty = object : MyClass(), MyTrait {}
+
+
+        private fun privateFunctionInner() = object : MyClass(), MyTrait {}
+
+        init {
+            privateFunctionInner().f1()
+            privateFunctionInner().f2()
+        }
+
+        protected fun protectedFunction() = object : MyClass(), MyTrait {}
+
+        fun internalFunction() = object : MyClass(), MyTrait {}
+
+        internal fun internal2Function() = object : MyClass(), MyTrait {}
+
+        public fun publicFunction() = object : MyClass(), MyTrait {}
+
+    }
+
+    fun foo() {
+        val localVar = object : MyClass(), MyTrait {}
+        localVar.f1()
+        localVar.f2()
+
+        fun foo2() = object : MyClass(), MyTrait {}
+        foo2().f1()
+        foo2().f2()
+    }
+
+}
+
+private val packagePrivateProperty = object : MyClass(), MyTrait {}
+
+protected val packageProtectedProperty = object : MyClass(), MyTrait {}
+
+val packageInternalProperty = object : MyClass(), MyTrait {}
+
+internal val packageInternal2Property = object : MyClass(), MyTrait {}
+
+public val packagePublicProperty = object : MyClass(), MyTrait {}
+
+protected fun packageProtectedFunction() = object : MyClass(), MyTrait {}
+
+fun packageInternalFunction() = object : MyClass(), MyTrait {}
+
+internal fun packageInternal2Function() = object : MyClass(), MyTrait {}
+
+public fun packagePublicFunction() = object : MyClass(), MyTrait {}
+
+fun fooPackage() {
+    val packageLocalVar = object : MyClass(), MyTrait {}
+    packageLocalVar.f1()
+    packageLocalVar.f2()
+
+    fun fooPackageLocal() = object : MyClass(), MyTrait {}
+    fooPackageLocal().f1()
+    fooPackageLocal().f2()
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/anonymousFunAsLastExpressionInBlock.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/anonymousFunAsLastExpressionInBlock.fir.kt
new file mode 100644
index 00000000000..c43ed114e65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/anonymousFunAsLastExpressionInBlock.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+// !CHECK_TYPE
+fun foo(block: () -> (() -> Int)) {}
+
+fun test() {
+    foo { fun(): Int {return 1} }
+    foo({ fun() = 1 })
+
+    val x1 =
+        if (1 == 1)
+            fun(): Int {return 1}
+        else
+            fun() = 1
+
+    val x2 =
+            if (1 == 1) {
+                fun(): Int {
+                    return 1
+                }
+            }
+            else
+                fun() = 1
+
+    val x3 = when (1) {
+        0 -> fun(): Int {return 1}
+        else -> fun() = 1
+    }
+
+    val x31 = when (1) {
+        0 -> {
+            fun(): Int {return 1}
+        }
+        else -> fun() = 1
+    }
+
+    val x4 = {
+        y: Int -> fun(): Int {return 1}
+    }
+
+    x4 checkType { <!UNRESOLVED_REFERENCE!>_<!><Function1<Int, Function0<Int>>>() }
+
+    { y: Int -> fun(): Int {return 1} }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/anonymousFunUnusedLastExpressionInBlock.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/anonymousFunUnusedLastExpressionInBlock.fir.kt
new file mode 100644
index 00000000000..e8ba7c71cb2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/anonymousFunUnusedLastExpressionInBlock.fir.kt
@@ -0,0 +1,21 @@
+fun unusedExpressions() {
+    if (1 == 1)
+        fun(): Int {return 1}
+    else
+        fun() = 1
+
+    if (1 == 1) {
+        fun(): Int {
+            return 1
+        }
+    }
+    else
+        fun() = 1
+
+    when (1) {
+        0 -> fun(): Int {return 1}
+        else -> fun() = 1
+    }
+
+    fun() = 1
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/DoubleDeclForLoop.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/DoubleDeclForLoop.fir.kt
new file mode 100644
index 00000000000..065d6ac7c48
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/DoubleDeclForLoop.fir.kt
@@ -0,0 +1,14 @@
+class A {
+    operator fun component1() = 1
+    operator fun component2() = 1
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x, y) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/FolLoopTypeComponentTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/FolLoopTypeComponentTypeMismatch.fir.kt
new file mode 100644
index 00000000000..bbbf1fca597
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/FolLoopTypeComponentTypeMismatch.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+class A {
+    operator fun component1() = 1
+    operator fun component2() = 1.0
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x: Double, y: Int) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionAmbiguity.fir.kt
new file mode 100644
index 00000000000..b9a927bbe78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionAmbiguity.fir.kt
@@ -0,0 +1,15 @@
+class A {
+    operator fun component1() = 1
+    operator fun component1() = 1
+    operator fun component2() = 1
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((<!AMBIGUITY!>x<!>, y) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionMissing.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionMissing.fir.kt
new file mode 100644
index 00000000000..068be345d66
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopComponentFunctionMissing.fir.kt
@@ -0,0 +1,13 @@
+class A {
+    operator fun component1() = 1
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x, <!UNRESOLVED_REFERENCE!>y<!>) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopMissingLoopParameter.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopMissingLoopParameter.fir.kt
new file mode 100644
index 00000000000..9bbbd640e91
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopMissingLoopParameter.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+fun useDeclaredVariables() {
+    <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for ((<!UNRESOLVED_REFERENCE!>a<!>, <!UNRESOLVED_REFERENCE!>b<!>)<!SYNTAX!><!>) {
+        a
+        b
+    }<!>
+}
+
+fun checkersShouldRun() {
+    <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for ((<!UNRESOLVED_REFERENCE!>@A a<!>, <!UNRESOLVED_REFERENCE!>_<!>)<!SYNTAX!><!>) {
+
+    }<!>
+}
+
+annotation class A
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopWithExtensions.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopWithExtensions.fir.kt
new file mode 100644
index 00000000000..30fca7424e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForLoopWithExtensions.fir.kt
@@ -0,0 +1,14 @@
+class A {
+}
+operator fun A.component1() = 1
+operator fun A.component2() = 1
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x, y) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForWithExplicitTypes.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForWithExplicitTypes.fir.kt
new file mode 100644
index 00000000000..3e97d2fc5ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/ForWithExplicitTypes.fir.kt
@@ -0,0 +1,14 @@
+class A {
+    operator fun component1() = 1
+    operator fun component2() = 1.0
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x: Int, y: Double) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/RedeclarationInForLoop.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/RedeclarationInForLoop.fir.kt
new file mode 100644
index 00000000000..36f980565b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/RedeclarationInForLoop.fir.kt
@@ -0,0 +1,14 @@
+class A {
+    operator fun component1() = 1
+    operator fun component2() = 1
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x, x) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/SingleDeclForLoop.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/SingleDeclForLoop.fir.kt
new file mode 100644
index 00000000000..660bec07ada
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/SingleDeclForLoop.fir.kt
@@ -0,0 +1,13 @@
+class A {
+    operator fun component1() = 1
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x) in C()) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationAssignedUnresolved.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationAssignedUnresolved.fir.kt
new file mode 100644
index 00000000000..d4235c70ed3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationAssignedUnresolved.fir.kt
@@ -0,0 +1,11 @@
+fun useDeclaredVariables() {
+    val (<!UNRESOLVED_REFERENCE!>a<!>, <!UNRESOLVED_REFERENCE!>b<!>) = <!UNRESOLVED_REFERENCE!>unresolved<!>
+    a
+    b
+}
+
+fun checkersShouldRun() {
+    val (<!UNRESOLVED_REFERENCE!>@A a<!>, <!UNRESOLVED_REFERENCE!>_<!>) = <!UNRESOLVED_REFERENCE!>unresolved<!>
+}
+
+annotation class A
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationMissingInitializer.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationMissingInitializer.fir.kt
new file mode 100644
index 00000000000..0cc0f05cc7e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/destructuringDeclarationMissingInitializer.fir.kt
@@ -0,0 +1,11 @@
+fun useDeclaredVariables() {
+    val (<!UNRESOLVED_REFERENCE!>a<!>, <!UNRESOLVED_REFERENCE!>b<!>)
+    a
+    b
+}
+
+fun checkersShouldRun() {
+    val (<!UNRESOLVED_REFERENCE!>@A a<!>, <!UNRESOLVED_REFERENCE!>_<!>)
+}
+
+annotation class A
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/kt2829.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/kt2829.fir.kt
new file mode 100644
index 00000000000..d907ea26ca0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/kt2829.fir.kt
@@ -0,0 +1,16 @@
+package test
+
+fun a(s: String) { // <- ERROR
+    val (x, y) = Pair("", s)
+    println(x + y)
+}
+
+fun b(s: String) {
+    val x = Pair("", s)
+    println(x)
+}
+
+//from library
+data class Pair<A, B>(val a: A, val b: B)
+
+fun println(a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/lastDestructuringDeclarationInBlock.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/lastDestructuringDeclarationInBlock.fir.kt
new file mode 100644
index 00000000000..69faf3e913c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/lastDestructuringDeclarationInBlock.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+fun test(list: A) {
+    if (true) {
+        val (c) = list
+    }
+    else {}
+
+    if (true) {
+        Unit
+        val (c) = list
+    }
+    else {}
+
+    when (1) {
+        1 -> {
+            val (c) = list
+        }
+    }
+
+    fn { it ->
+        val (a) = it
+    }
+}
+
+class A {
+    operator fun component1() = 1
+}
+
+fun fn(x: (A) -> Unit) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/underscore.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/underscore.fir.kt
new file mode 100644
index 00000000000..10556a5c3dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/destructuringDeclarations/underscore.fir.kt
@@ -0,0 +1,51 @@
+// !WITH_NEW_INFERENCE
+
+class A {
+    operator fun component1() = 1
+    operator fun component2() = ""
+}
+
+class C {
+    operator fun iterator(): Iterator<A> = null!!
+}
+
+fun test() {
+    for ((x, _) in C()) {
+        foo(x, _)
+    }
+
+    for ((_, y) in C()) {
+        foo(_, y)
+    }
+
+    for ((_, _) in C()) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(_, _)
+    }
+
+    for ((_ : Int, _ : String) in C()) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(_, _)
+    }
+
+    for ((_ : String, _ : Int) in C()) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(_, _)
+    }
+
+    val (x, _) = A()
+    val (_, y) = A()
+
+    foo(x, y)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(x, _)
+    foo(_, y)
+
+    val (`_`, z) = A()
+
+    foo(_, z)
+
+    val (_, `_`) = A()
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(_, y)
+
+    val (unused, _) = A()
+}
+
+fun foo(x: Int, y: String) {}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/CasesWithOneTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/CasesWithOneTypeParameter.fir.kt
new file mode 100644
index 00000000000..16c6cc9b815
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/CasesWithOneTypeParameter.fir.kt
@@ -0,0 +1,17 @@
+interface A0<T : A0<T>>
+interface A1<T : A1<*>>
+interface A2<T : A2<out T>>
+// StackOverflowError
+//interface A3<T : A3<in T>>
+interface A4<T : A4<*>?>
+
+interface B0<T : B1<*>>
+interface B1<T : B0<*>>
+
+interface AA<T: AA<*>>
+interface BB<S : List<AA<*>>>
+
+interface A<T: List<T, T, T>>
+
+class X<Y>
+class D<T : X<in X<out X<T>>>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/CasesWithTwoTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/CasesWithTwoTypeParameters.fir.kt
new file mode 100644
index 00000000000..cb7f8d4438f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/CasesWithTwoTypeParameters.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UPPER_BOUND_VIOLATED
+
+interface C0<T, S : C0<*, S>>
+
+interface C1<T : C1<T, *>, S : C1<S, *>>   // T -> S, S -> S
+interface C2<T : C2<T, *>, S : C2<*, S>>   // T -> S, S -> T
+
+interface D1<T, U> where T : U, U: D1<*, U>
+interface D2<T, U> where T : U?, U: D2<*, *>
+interface D3<T, U, V> where T : U, U : V, V: D3<*, *, V>
+
+interface A<T, U> where T : A<U, T>, U: A<T, A<in U, T>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/JavaSuperType.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/JavaSuperType.fir.kt
new file mode 100644
index 00000000000..48fa31cfc5c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/finiteBoundRestriction/JavaSuperType.fir.kt
@@ -0,0 +1,5 @@
+// FILE: A.java
+public class A<T extends A> {}
+
+// FILE: 1.kt
+class B<S: A<*>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/illegalModifiersOnClass.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/illegalModifiersOnClass.fir.kt
new file mode 100644
index 00000000000..342314424da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/illegalModifiersOnClass.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -MANY_COMPANION_OBJECTS -REDECLARATION -DUPLICATE_CLASS_NAMES
+
+// KT-3464 Front-end shouldn't allow override modifier in class declaration
+
+override class A {
+    override companion object {}
+    open companion object {}
+    abstract companion object {}
+    final companion object {}
+}
+
+override object B1 {}
+open object B2 {}
+abstract object B3 {}
+final object B4 {}
+
+override enum class C {}
+override interface D {}
+override annotation class E
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kClassInSignature.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kClassInSignature.fir.kt
new file mode 100644
index 00000000000..9a1eca03800
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kClassInSignature.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -TYPE_PARAMETER_AS_REIFIED -TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+fun <T> test1() = <!OTHER_ERROR!>T<!>::class
+fun <T : Any> test2() = <!OTHER_ERROR!>T<!>::class
+
+val <T> test3 = <!OTHER_ERROR!>T<!>::class
+val <T> test4 get() = <!OTHER_ERROR!>T<!>::class
+
+fun <T> test5() = listOf(<!OTHER_ERROR!>T<!>::class)
+
+fun <T> test6(): kotlin.reflect.KClass<T> = <!OTHER_ERROR!>T<!>::class
+fun <T> test7(): kotlin.reflect.KClass<*> = <!OTHER_ERROR!>T<!>::class
+fun test8() = String?::class
+
+fun <T> listOf(e: T): List<T> = null!!
+
+fun <L> locals() {
+    fun <T> test1() = <!OTHER_ERROR!>T<!>::class
+    fun <T : Any> test2() = <!OTHER_ERROR!>T<!>::class
+
+    val test3 = <!OTHER_ERROR!>L<!>::class
+    fun test4() = <!OTHER_ERROR!>L<!>::class
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt1141.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt1141.fir.kt
new file mode 100644
index 00000000000..bf8bdff235d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt1141.fir.kt
@@ -0,0 +1,21 @@
+//KT-1141 No check that object in 'object expression' implements all abstract members of supertype
+
+package kt1141
+
+public interface SomeTrait {
+    fun foo()
+}
+
+fun foo() {
+    val x = object : SomeTrait {
+    }
+    x.foo()
+}
+
+object Rr : SomeTrait {}
+
+class C : SomeTrait {}
+
+fun foo2() {
+    val r = object : Runnable {} //no error
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt1193.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt1193.fir.kt
new file mode 100644
index 00000000000..b26f7fcbaf5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt1193.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+//KT-1193 Check enum entry supertype / initialization
+
+package kt1193
+
+enum class MyEnum(val i: Int) {
+    A(12),
+    B  //no error
+}
+
+open class A(x: Int = 1)
+
+val x: MyEnum = MyEnum.A
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt2096.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt2096.fir.kt
new file mode 100644
index 00000000000..94875fba26f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt2096.fir.kt
@@ -0,0 +1,7 @@
+//KT-2096 Abstract property with no type specified causes compiler to crash
+
+package c
+
+abstract class Foo{
+    protected abstract val prop
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt2142.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt2142.fir.kt
new file mode 100644
index 00000000000..4410e01c0a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt2142.fir.kt
@@ -0,0 +1,8 @@
+//KT-2142 function local classes do not work
+
+package a
+
+fun foo() {
+    class Foo() {}
+    Foo() // Unresolved reference Foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt2397.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt2397.fir.kt
new file mode 100644
index 00000000000..2f85101af3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt2397.fir.kt
@@ -0,0 +1,17 @@
+//KT-2397 Prohibit final methods in traits with no implementation
+package a
+
+interface T {
+    final fun foo()
+    final val b : Int
+
+    final fun bar() {}
+    final val c : Int
+       get() = 42
+
+    final val d = 1
+}
+
+class A {
+    final fun foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt2631_MultipleDeclaration.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt2631_MultipleDeclaration.fir.kt
new file mode 100644
index 00000000000..3a8cba18859
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt2631_MultipleDeclaration.fir.kt
@@ -0,0 +1,27 @@
+// !CHECK_TYPE
+
+//KT-2631 Check multiple assignment
+package a
+
+class MyClass {
+    operator fun component1() = 1
+    operator fun component2() = "a"
+}
+
+class MyClass2 {}
+
+operator fun MyClass2.component1() = 1.2
+
+fun test(mc1: MyClass, mc2: MyClass2) {
+    val (a, b) = mc1
+    checkSubtype<Int>(a)
+    checkSubtype<String>(b)
+
+    val (c) = mc2
+    checkSubtype<Double>(c)
+
+    //check no error types
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Boolean>(a)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Boolean>(b)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Boolean>(c)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt2643MultiDeclInControlFlow.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt2643MultiDeclInControlFlow.fir.kt
new file mode 100644
index 00000000000..bce3e510276
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt2643MultiDeclInControlFlow.fir.kt
@@ -0,0 +1,27 @@
+//KT-2643 Support multi-declarations in Data-Flow analysis
+package n
+
+class C {
+    operator fun component1() = 1
+    operator fun component2() = 2
+}
+
+fun test1(c: C) {
+    val (a, b) = c
+}
+
+fun test2(c: C) {
+    val (a, b) = c
+    a + 3
+}
+
+fun test3(c: C) {
+    var (a, b) = c
+    a = 3
+}
+
+fun test4(c: C) {
+    var (a, b) = c
+    a = 3
+    a + 1
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/kt559.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/kt559.fir.kt
new file mode 100644
index 00000000000..9a9657ce04a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/kt559.fir.kt
@@ -0,0 +1,30 @@
+//KT-559 Forbid abstract method call through super
+
+package kt559
+
+abstract class A {
+    abstract val i : Int
+
+    abstract fun foo() : Int
+
+    fun fff() {}
+}
+
+abstract class D(): A() {
+    override val i : Int = 34
+}
+
+class C() : D() {
+    fun test() {
+        super.i
+    }
+}
+
+class B() : A() {
+    override fun foo(): Int {
+        super.i
+
+        super.fff() //everything is ok
+        return super.foo()  //no error!!
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/localDeclarationModifiers.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/localDeclarationModifiers.fir.kt
new file mode 100644
index 00000000000..6b7a7bc265a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/localDeclarationModifiers.fir.kt
@@ -0,0 +1,12 @@
+package d
+
+class T {
+    fun baz() = 1
+}
+
+fun foo() {
+    public val i = 11
+    abstract val j
+    override fun T.baz() = 2
+    private fun bar() = 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/localFunctionNoInheritVisibility.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/localFunctionNoInheritVisibility.fir.kt
new file mode 100644
index 00000000000..9cb85c36042
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/localFunctionNoInheritVisibility.fir.kt
@@ -0,0 +1,16 @@
+package d
+
+class T {
+    fun baz() = 1
+}
+
+override fun zzz() {}
+
+fun foo(t: T) {
+    override fun T.baz() = 2
+
+    // was "Visibility is unknown yet exception"
+    t.baz()
+
+    zzz()
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/localVariablesWithTypeParameters_1_3.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/localVariablesWithTypeParameters_1_3.fir.kt
new file mode 100644
index 00000000000..23ee4fd91c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/localVariablesWithTypeParameters_1_3.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !LANGUAGE: -ProhibitTypeParametersForLocalVariables
+
+import kotlin.reflect.KProperty
+
+fun test() {
+    val <T> a0 = 0
+    val <T : __UNRESOLVED__> a1 = ""
+    val <T : String> a2 = 0
+    const val <T> a3 = 0
+    lateinit val <T> a4 = 0
+    val <T> a5 by Delegate<Int>()
+    val <T> a6 by Delegate<T>()
+}
+
+class Delegate<F> {
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): String = ""
+    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/localVariablesWithTypeParameters_1_4.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/localVariablesWithTypeParameters_1_4.fir.kt
new file mode 100644
index 00000000000..7aa9f13ca44
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/localVariablesWithTypeParameters_1_4.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !LANGUAGE: +ProhibitTypeParametersForLocalVariables
+
+import kotlin.reflect.KProperty
+
+fun test() {
+    val <T> a0 = 0
+    val <T : __UNRESOLVED__> a1 = ""
+    val <T : String> a2 = 0
+    const val <T> a3 = 0
+    lateinit val <T> a4 = 0
+    val <T> a5 by Delegate<Int>()
+    val <T> a6 by Delegate<T>()
+}
+
+class Delegate<F> {
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): String = ""
+    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/mulitpleVarargParameters.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/mulitpleVarargParameters.fir.kt
new file mode 100644
index 00000000000..a51b6884050
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/mulitpleVarargParameters.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PRIMARY_CONSTRUCTOR_DELEGATION_CALL_EXPECTED
+fun test(vararg x1: Int, vararg x2: Int) {
+    fun test2(vararg x1: Int, vararg x2: Int) {
+        class LocalClass(vararg x1: Int, vararg x2: Int) {
+        constructor(vararg x1: Int, vararg x2: Int, xx: Int) {}
+    }
+        fun test3(vararg x1: Int, vararg x2: Int) {}
+    }
+}
+
+fun Any.test(vararg x1: Int, vararg x2: Int, vararg x3: Int) {}
+
+interface I {
+    fun test(vararg x1: Int, vararg x2: Int)
+}
+
+abstract class C(vararg x1: Int, vararg x2: Int, b: Boolean) {
+    fun test(vararg x1: Int, vararg x2: Int) {}
+
+    abstract fun test2(vararg x1: Int, vararg x2: Int)
+
+    class CC(vararg x1: Int, vararg x2: Int, b: Boolean) {
+        constructor(vararg x1: Int, vararg x2: Int) {}
+        fun test(vararg x1: Int, vararg x2: Int) {}
+    }
+}
+
+object O {
+    fun test(vararg x1: Int, vararg x2: Int) {}
+
+    class CC(vararg x1: Int, vararg x2: Int, b: Boolean) {
+        constructor(vararg x1: Int, vararg x2: Int) {}
+        fun test(vararg x1: Int, vararg x2: Int) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/namedFunAsLastExpressionInBlock.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/namedFunAsLastExpressionInBlock.fir.kt
new file mode 100644
index 00000000000..6bfd3b74317
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/namedFunAsLastExpressionInBlock.fir.kt
@@ -0,0 +1,75 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+// !CHECK_TYPE
+fun foo(block: () -> (() -> Int)) {}
+
+fun test() {
+    val x = <!INFERENCE_ERROR, INFERENCE_ERROR, INFERENCE_ERROR!>fun named1(x: Int): Int { return 1 }<!>
+    x <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Function1<Int, Int>>() }
+
+    foo { fun named2(): Int {return 1} }
+    foo({ fun named3() = 1 })
+
+    val x1 =
+    if (1 == 1)
+    // TODO: Diagnostic content could be better
+    <!SYNTAX!><!>fun named4(): Int {return 1}
+    <!SYNTAX!>else<!>
+    fun named5() = 1
+
+    val x2 =
+    if (1 == 1) {
+        fun named6(): Int {
+            return 1
+        }
+    }
+    else
+    <!SYNTAX!><!>fun named7() = 1
+
+    val x3 = when (1) {
+        0 -> fun named8(): Int {return 1}
+        else -> fun named9() = 1
+    }
+
+    val x31 = when (1) {
+        0 -> {
+            fun named10(): Int {return 1}
+        }
+        else -> fun named11() = 1
+    }
+
+    val x4 = {
+        y: Int -> fun named12(): Int {return 1}
+    }
+
+    x4 checkType { <!UNRESOLVED_REFERENCE!>_<!><Function1<Int, Unit>>() }
+
+    { y: Int -> fun named14(): Int {return 1} }
+    val b = <!UNRESOLVED_REFERENCE!><!INFERENCE_ERROR!>(fun named15(): Boolean { return true })<!>()<!>
+
+    baz(<!INFERENCE_ERROR!>fun named16(){}<!>)
+}
+
+fun bar() = <!INFERENCE_ERROR, INFERENCE_ERROR, INFERENCE_ERROR!>fun named() {}<!>
+
+fun <T> run(block: () -> T): T = null!!
+fun run2(block: () -> Unit): Unit = null!!
+fun baz(obj: Any?) {}
+
+fun success() {
+    run { fun named1() = 1 }
+    run2 { fun named2() = 1 }
+
+    val x = run { fun named3() = 1 }
+    x checkType { <!UNRESOLVED_REFERENCE!>_<!><Unit>() }
+
+    val y = when (1) {
+        0 -> {
+            fun named4(): Int {return 1}
+        }
+        else -> {
+            fun named5(): Int {return 1}
+        }
+    }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><Unit>() }
+}
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/JavaWithKotlin.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/JavaWithKotlin.fir.kt
new file mode 100644
index 00000000000..f26dc514958
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/JavaWithKotlin.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UPPER_BOUND_VIOLATED
+
+//// FILE: D.java
+public interface D<W> {}
+
+// FILE: Q.java
+public interface Q<Z1, Z2> {}
+
+// FILE: C.java
+public interface C<X> extends D<P<X,X>> {}
+
+// FILE: 1.kt
+interface P<Y1, Y2> : Q<C<Y1>, C<D<Y2>>>
+
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/JavaWithKotlin2.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/JavaWithKotlin2.fir.kt
new file mode 100644
index 00000000000..0e95d892f06
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/JavaWithKotlin2.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UPPER_BOUND_VIOLATED
+
+//// FILE: D.java
+public interface D<W> {}
+
+// FILE: Q.java
+public interface Q<Z1, Z2> {}
+
+// FILE: C.java
+public interface C<X> extends D<P<X,X>> {}
+
+// FILE: P.java
+public interface P<Y1, Y2> extends Q<C<Y1>, C<D<Y2>>> {}
+
+// FILE: 1.kt
+interface P1<YY1, YY2> : P<YY1, YY2>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/PureKotlin.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/PureKotlin.fir.kt
new file mode 100644
index 00000000000..378bbb5bd72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/nonExpansiveInheritanceRestriction/PureKotlin.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UPPER_BOUND_VIOLATED
+
+interface A<T>
+interface B<T> : A<A<*>>
+
+interface N0<in T>
+interface C0<X> : N0<N0<C0<C0<X>>>>
+
+interface N1<in T>
+interface C1<X> : N1<N1<C1<C1<X?>>>>
+interface C2<T> : C1<C1<T>>
+
+interface C<X> : D<P<X, X>>
+interface P<Y1, Y2> : Q<C<Y1>, C<D<Y2>>>
+interface Q<Z1, Z2>
+interface D<W>
+
+interface E0<T>
+interface E1<T : E2>
+interface E2 : E0<E1<out E2>>
+
+interface F0<T>
+interface F1<T : F2<*>, U : F2<*>>
+interface F2<T> : F0<F1<out F2<*>, T>>
+
+interface G0<T>
+interface G1<T : U, U : G2<*>>
+interface G2<T> : G0<G1<out G2<*>, T>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/packageDeclarationModifiers.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/packageDeclarationModifiers.fir.kt
new file mode 100644
index 00000000000..a7bf8455a1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/packageDeclarationModifiers.fir.kt
@@ -0,0 +1,12 @@
+package d
+
+abstract val a : Int = 1
+
+override val c : Int = 1
+
+final fun foo() = 2
+
+abstract fun baz() = 2
+
+class T {}
+override fun T.bar() = 2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/propertyInPackageHasNoInheritVisibility.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/propertyInPackageHasNoInheritVisibility.fir.kt
new file mode 100644
index 00000000000..e0a5a606190
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/propertyInPackageHasNoInheritVisibility.fir.kt
@@ -0,0 +1,10 @@
+package d
+
+override val f : ()-> Int = { 12 }
+
+fun test() {
+    f()
+}
+
+var g: Int = 1
+    protected set(i: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/sealedOnMembers.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/sealedOnMembers.fir.kt
new file mode 100644
index 00000000000..fd7e97ebe76
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/sealedOnMembers.fir.kt
@@ -0,0 +1,18 @@
+interface A {
+    sealed fun foo()
+    sealed var bar: Unit
+}
+
+interface B {
+    abstract fun foo()
+    abstract var bar: Unit
+}
+
+interface C : A, B
+
+abstract class D(sealed var x: Int) {
+    abstract var y: Unit
+        sealed set
+}
+
+abstract class E : D(42)
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/unambiguousObjectExpressionType.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/unambiguousObjectExpressionType.fir.kt
new file mode 100644
index 00000000000..edca51dff64
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/unambiguousObjectExpressionType.fir.kt
@@ -0,0 +1,175 @@
+open class MyClass {
+    fun f1() {}
+}
+
+
+class Foo {
+
+    protected val protectedProperty = object : MyClass() {}
+
+    public val publicProperty = object : MyClass() {}
+
+    protected val protected2Property : MyClass = object : MyClass() {fun invisible() {}}
+
+    public val public2Property : MyClass = object : MyClass() {fun invisible() {}}
+
+    private val privateProperty = object : MyClass() {fun visible() {}}
+
+    internal val internalProperty = object : MyClass() { fun invisible() {}}
+
+
+    fun testProperties() {
+        privateProperty.f1()
+        internalProperty.f1()
+        protected2Property.f1()
+        public2Property.f1()
+
+        privateProperty.visible()
+        protected2Property.<!UNRESOLVED_REFERENCE!>invisible<!>()
+        public2Property.<!UNRESOLVED_REFERENCE!>invisible<!>()
+        internalProperty.invisible()
+    }
+
+
+    protected fun protectedFunction() = object : MyClass() {}
+
+    public fun publicFunction() = object : MyClass() {}
+
+    protected fun protected2Function(): MyClass = object : MyClass() {fun visible() {}}
+
+    public fun public2Function(): MyClass = object : MyClass() {fun visible() {}}
+
+    private fun privateFunction() = object : MyClass() {fun visible() {}}
+
+    internal fun internalFunction() = object : MyClass() {fun invisible() {}}
+
+
+    fun testFunctions() {
+        privateFunction().f1()
+        internalFunction().f1()
+        public2Function().f1()
+        protected2Function().f1()
+
+        privateFunction().visible()
+        internalFunction().invisible()
+        public2Function().<!UNRESOLVED_REFERENCE!>invisible<!>()
+        protected2Function().<!UNRESOLVED_REFERENCE!>invisible<!>()
+    }
+
+
+    class FooInner {
+
+        public val publicProperty = object : MyClass() {}
+
+        protected val protectedProperty = object : MyClass() {}
+
+        protected val protected2Property : MyClass = object : MyClass() {fun invisible() {}}
+
+        public val public2Property : MyClass = object : MyClass() {fun invisible() {}}
+
+        private val privateProperty = object : MyClass() {fun visible() {}}
+
+        internal val internalProperty = object : MyClass() { fun invisible() {}}
+
+
+        fun testProperties() {
+            privateProperty.f1()
+            internalProperty.f1()
+            protected2Property.f1()
+            public2Property.f1()
+
+            privateProperty.visible()
+            protected2Property.<!UNRESOLVED_REFERENCE!>invisible<!>()
+            public2Property.<!UNRESOLVED_REFERENCE!>invisible<!>()
+            internalProperty.invisible()
+        }
+
+
+        protected fun protectedFunction() = object : MyClass() {}
+
+        public fun publicFunction() = object : MyClass() {}
+
+        protected fun protected2Function(): MyClass = object : MyClass() {fun visible() {}}
+
+        public fun public2Function(): MyClass = object : MyClass() {fun visible() {}}
+
+        private fun privateFunction() = object : MyClass() {fun visible() {}}
+
+        internal fun internalFunction() = object : MyClass() {fun invisible() {}}
+
+
+        fun testFunctions() {
+            privateFunction().f1()
+            internalFunction().f1()
+            public2Function().f1()
+            protected2Function().f1()
+
+            privateFunction().visible()
+            internalFunction().invisible()
+            public2Function().<!UNRESOLVED_REFERENCE!>invisible<!>()
+            protected2Function().<!UNRESOLVED_REFERENCE!>invisible<!>()
+        }
+    }
+
+    fun foo() {
+        val localVar = object : MyClass() {}
+        localVar.f1()
+        fun foo2() = object : MyClass() {}
+        foo2().f1()
+    }
+
+}
+
+protected val packageProtectedProperty = object : MyClass() {}
+
+public val packagePublicProperty = object : MyClass() {}
+
+public val packagePublic2Property : MyClass = object : MyClass() {fun invisible() {}}
+
+private val packagePrivateProperty = object : MyClass() {fun invisible() {}}
+
+internal val packageInternalProperty = object : MyClass() {fun invisible() {}}
+
+
+fun testProperties() {
+    packagePrivateProperty.f1()
+    packageInternalProperty.f1()
+    packagePublic2Property.f1()
+
+    packagePrivateProperty.invisible()
+    packageInternalProperty.invisible()
+    packagePublic2Property.<!UNRESOLVED_REFERENCE!>invisible<!>()
+}
+
+
+private fun privateFunction() = object : MyClass() {fun invisible() {}}
+
+protected fun protectedFunction() = object : MyClass() {}
+
+public fun publicFunction() = object : MyClass() {}
+
+public fun public2Function() : MyClass = object : MyClass() {fun invisible() {}}
+
+internal fun internalFunction() = object : MyClass() {fun invisible() {}}
+
+
+
+fun testFunctions() {
+    privateFunction().f1()
+    internalFunction().f1()
+    public2Function().f1()
+
+    privateFunction().invisible()
+    internalFunction().invisible()
+    public2Function().<!UNRESOLVED_REFERENCE!>invisible<!>()
+}
+
+fun fooPackage() {
+    val packageLocalVar = object : MyClass() {fun visible() {}}
+    packageLocalVar.f1()
+    packageLocalVar.visible()
+
+    fun fooPackageLocal() = object : MyClass() {fun visible() {}}
+    fooPackageLocal().f1()
+    fooPackageLocal().visible()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/declarationChecks/valVarFunctionParameter.fir.kt b/compiler/testData/diagnostics/tests/declarationChecks/valVarFunctionParameter.fir.kt
new file mode 100644
index 00000000000..8ddd32db866
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/declarationChecks/valVarFunctionParameter.fir.kt
@@ -0,0 +1,12 @@
+fun f(
+        val a: Int,
+        var b: Int,
+        c: Int,
+        vararg var d: Int,
+        vararg val e: Int,
+        vararg f: Int
+) {
+    
+    
+    a + b + c + d[0] + e[0] + f[0] // to avoid 'unused parameter'
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/defaultArguments/kt5232.fir.kt b/compiler/testData/diagnostics/tests/defaultArguments/kt5232.fir.kt
new file mode 100644
index 00000000000..c41593397bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/defaultArguments/kt5232.fir.kt
@@ -0,0 +1,11 @@
+interface A {
+    fun visit(a:Int, b:String="") : String = b + a
+}
+
+class B : A {
+    override fun visit(a:Int, b:String) : String = b + a
+}
+
+class C : A {
+    override fun visit(a:Int) : String = "" + a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/defaultArguments/superCall.fir.kt b/compiler/testData/diagnostics/tests/defaultArguments/superCall.fir.kt
new file mode 100644
index 00000000000..77305e62156
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/defaultArguments/superCall.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -ABSTRACT_SUPER_CALL
+
+abstract class A {
+    open fun foo(a: String = "default") {
+    }
+
+    final fun foo2(a: String = "default") {
+    }
+
+    abstract fun foo3(a: String = "default")
+}
+
+open class B : A() {
+    fun test() {
+        super.foo("123")
+        super.foo()
+
+        super.foo2("123")
+        super.foo2()
+
+        super.foo3("123")
+        super.foo3()
+    }
+
+    override fun foo3(a: String) {
+        throw UnsupportedOperationException()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/absentErrorAboutInitializer.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/absentErrorAboutInitializer.fir.kt
new file mode 100644
index 00000000000..293bb83f024
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/absentErrorAboutInitializer.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val a: Int by Delegate()
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/absentErrorAboutType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/absentErrorAboutType.fir.kt
new file mode 100644
index 00000000000..4276b095160
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/absentErrorAboutType.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val a by Delegate()
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/abstractDelegatedProperty.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/abstractDelegatedProperty.fir.kt
new file mode 100644
index 00000000000..14895513007
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/abstractDelegatedProperty.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+abstract class A {
+    abstract val a: Int by Delegate()
+}
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/backingField.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/backingField.fir.kt
new file mode 100644
index 00000000000..7ad3dc1881f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/backingField.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class B {
+    val a: Int by Delegate()
+
+    fun foo() =<!SYNTAX!><!> <!SYNTAX!>$a<!>
+}
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/defaultGetter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/defaultGetter.fir.kt
new file mode 100644
index 00000000000..7b2135dd43f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/defaultGetter.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val a: Int by Delegate()
+    get
+
+class Delegate {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int {
+        return 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/defaultSetter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/defaultSetter.fir.kt
new file mode 100644
index 00000000000..b64b84beb28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/defaultSetter.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+var a: Int by Delegate()
+    private set
+
+class Delegate {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int {
+        return 1
+    }
+
+    operator fun setValue(t: Any?, p: KProperty<*>, i: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/delegatedPropertyOverridedInTrait.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/delegatedPropertyOverridedInTrait.fir.kt
new file mode 100644
index 00000000000..1a63e3362c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/delegatedPropertyOverridedInTrait.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+interface A {
+    val prop: Int
+}
+
+class AImpl: A  {
+    override val prop by Delegate()
+}
+
+fun foo() {
+    AImpl().prop
+}
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/delegatedPropertyOverridedInTraitTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/delegatedPropertyOverridedInTraitTypeMismatch.fir.kt
new file mode 100644
index 00000000000..d23a9803b84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/delegatedPropertyOverridedInTraitTypeMismatch.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+interface A {
+    val prop: Int
+}
+
+class AImpl: A  {
+    override val prop by Delegate()
+}
+
+fun foo() {
+    AImpl().prop
+}
+
+class Delegate {
+    operator fun getValue(t: Any?, p: KProperty<*>): String {
+        return ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/disallowImplInTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/disallowImplInTypeParameter.fir.kt
new file mode 100644
index 00000000000..6c6e19266f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/disallowImplInTypeParameter.fir.kt
@@ -0,0 +1,7 @@
+import kotlin.reflect.KProperty0
+
+val a: Int by A()
+
+class A {
+    fun getValue(t: Any?, p: KProperty0<*>): Int = 1
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/genericGetter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/genericGetter.fir.kt
new file mode 100644
index 00000000000..8c841bef535
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/genericGetter.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val a: Int by A(1)
+
+class A<T: Any>(i: T) {
+  operator fun getValue(t: Any?, p: KProperty<*>): T {
+    throw Exception()
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/getterWithSubtype.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/getterWithSubtype.fir.kt
new file mode 100644
index 00000000000..c567c076187
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/getterWithSubtype.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+open class Base
+class Derived: Base()
+
+val a: Base by A()
+
+class A {
+  operator fun getValue(t: Any?, p: KProperty<*>): Derived {
+    return Derived()
+  }
+}
+
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inTrait.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inTrait.fir.kt
new file mode 100644
index 00000000000..cbffec8a11e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inTrait.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+interface T {
+  val a: Int by Delegate()
+}
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/incompleteTypeInference.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/incompleteTypeInference.fir.kt
new file mode 100644
index 00000000000..8a6d09a8a9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/incompleteTypeInference.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A
+
+class D {
+    val c: Int by IncorrectThis<A>()
+}
+
+val cTopLevel: Int by IncorrectThis<A>()
+
+class IncorrectThis<T> {
+    fun <R> get(t: Any?, p: KProperty<*>): Int {
+        return 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/callableReferenceArgumentInDelegatedExpression.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/callableReferenceArgumentInDelegatedExpression.fir.kt
new file mode 100644
index 00000000000..8025b9d7d9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/callableReferenceArgumentInDelegatedExpression.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class Inv2<T, K>
+
+fun <T, K> create(g: (T) -> K): Inv2<T, K> = TODO()
+
+operator fun <S1, V1> Inv2<S1, V1>.getValue(o: Sample, desc: KProperty<*>): V1 = TODO()
+operator fun <S2, V2> Inv2<S2, V2>.setValue(o: Sample, desc: KProperty<*>, value: V2) {}
+
+class Version(val version: Int)
+
+class Sample {
+    var version: Version by create(::Version)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/delegateExpressionAsLambda.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/delegateExpressionAsLambda.fir.kt
new file mode 100644
index 00000000000..2f1e994bd1e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/delegateExpressionAsLambda.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+fun test(i: Int) {
+    val bad by myLazyDelegate {
+        createSample(i) { it.toString() }
+    }
+
+    <!INAPPLICABLE_CANDIDATE!>takeSample<!>(bad)
+}
+
+fun <T> myLazyDelegate(i: () -> T): LazyDelegate<T> = LazyDelegate(i())
+
+class LazyDelegate<T>(val v: T) {
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = TODO()
+}
+
+class Sample<K, V>
+
+fun takeSample(g: Sample<Int, String>) {}
+fun <T, S> createSample(i: T, a: (T) -> S): Sample<T, S> = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/differentDelegatedExpressions.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/differentDelegatedExpressions.fir.kt
new file mode 100644
index 00000000000..6e5716a408a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/differentDelegatedExpressions.fir.kt
@@ -0,0 +1,53 @@
+// !WITH_NEW_INFERENCE
+package baz
+
+import kotlin.reflect.KProperty
+
+class A(outer: Outer) {
+    var i: String by  + getMyConcreteProperty()
+    var d: String by  getMyConcreteProperty() - 1
+    var c: String by  O.getMyProperty()
+    var g: String by  outer.getContainer().getMyProperty()
+
+
+    var b: String by  foo(getMyProperty())
+    var r: String by  foo(outer.getContainer().getMyProperty())
+    var e: String by  + foo(getMyProperty())
+    var f: String by  foo(getMyProperty()) - 1
+}
+
+fun <A, B> foo(a: Any?) = MyProperty<A, B>()
+
+fun <A, B> getMyProperty() = MyProperty<A, B>()
+
+fun getMyConcreteProperty() = MyProperty<Any?, String>()
+
+class MyProperty<R, T> {
+
+    operator fun getValue(thisRef: R, desc: KProperty<*>): T {
+        println("get $thisRef ${desc.name}")
+        return null as T
+    }
+
+    operator fun setValue(thisRef: R, desc: KProperty<*>, value: T) {
+        println("set $thisRef ${desc.name} $value")
+    }
+}
+
+operator fun <R, T> MyProperty<R, T>.unaryPlus() = MyProperty<R, T>()
+operator fun <R, T> MyProperty<R, T>.minus(i: Int) = MyProperty<R, T>()
+
+object O {
+    fun <A, B> getMyProperty() = MyProperty<A, B>()
+}
+
+interface MyPropertyContainer {
+    fun <R, T> getMyProperty(): MyProperty<R, T>
+}
+
+interface Outer {
+    fun getContainer(): MyPropertyContainer
+}
+
+// -----------------
+fun println(a: Any?) = a
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/extensionGet.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/extensionGet.fir.kt
new file mode 100644
index 00000000000..ad70419a6b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/extensionGet.fir.kt
@@ -0,0 +1,35 @@
+package foo
+
+import kotlin.reflect.KProperty
+
+class A1 {
+    val a: String by MyProperty1()
+}
+
+class MyProperty1 {}
+operator fun MyProperty1.getValue(thisRef: Any?, desc: KProperty<*>): String {
+    throw Exception("$thisRef $desc")
+}
+
+//--------------------
+
+class A2 {
+    val a: String by MyProperty2()
+}
+
+class MyProperty2<T> {}
+operator fun <T> MyProperty2<T>.getValue(thisRef: Any?, desc: KProperty<*>): T {
+    throw Exception("$thisRef $desc")
+}
+
+//--------------------
+
+class A3 {
+    val a: String by MyProperty3()
+
+    class MyProperty3<T> {}
+
+    operator fun <T> MyProperty3<T>.getValue(thisRef: Any?, desc: KProperty<*>): T {
+        throw Exception("$thisRef $desc")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/extensionProperty.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/extensionProperty.fir.kt
new file mode 100644
index 00000000000..e34203d0b3c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/extensionProperty.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+package foo
+
+import kotlin.reflect.KProperty
+
+open class A {
+    val B.w: Int by MyProperty()
+}
+
+val B.r: Int by MyProperty()
+
+val A.e: Int by MyProperty()
+
+class B {
+    val A.f: Int by MyProperty()
+}
+
+class MyProperty<R : A, T> {
+    operator fun getValue(thisRef: R, desc: KProperty<*>): T {
+        throw Exception("$thisRef $desc")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/genericMethodInGenericClass.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/genericMethodInGenericClass.fir.kt
new file mode 100644
index 00000000000..9ac6919c7db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/genericMethodInGenericClass.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A<R>() {
+    operator fun <T> getValue(t: Any?, p: KProperty<*>): T = null!!
+    operator fun <T> setValue(t: Any?, p: KProperty<*>, x: T) = Unit
+}
+
+var a1: Int by A()
+var a2: Int by A<String>()
+
+class B<R>() {
+    operator fun <T> getValue(t: Any?, p: KProperty<*>): T = null!!
+    operator fun setValue(t: Any?, p: KProperty<*>, x: R) = Unit
+}
+
+var b1: Int by B()
+var b2: Int by B<Number>()
+
+class C<R>() {
+    operator fun getValue(t: Any?, p: KProperty<*>): R = null!!
+    operator fun <T> setValue(t: Any?, p: KProperty<*>, x: T) = Unit
+}
+
+var c1: Int by C()
+var c2: Int by C<Number>()
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/genericMethods.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/genericMethods.fir.kt
new file mode 100644
index 00000000000..eae33a570c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/genericMethods.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+import kotlin.reflect.KProperty
+
+var a: Int by A()
+var a1 by A()
+
+var b: Int by B()
+
+val cObj = C()
+var c: String by cObj
+
+class A {
+  operator fun <T> getValue(t: Any?, p: KProperty<*>): T = null!!
+  operator fun <T> setValue(t: Any?, p: KProperty<*>, x: T) = Unit
+}
+
+class B
+
+operator fun <T> B.getValue(t: Any?, p: KProperty<*>): T = null!!
+operator fun <T> B.setValue(t: Any?, p: KProperty<*>, x: T) = Unit
+
+class C
+
+operator inline fun <reified T> C.getValue(t: Any?, p: KProperty<*>): T = null!!
+operator inline fun <reified T> C.setValue(t: Any?, p: KProperty<*>, x: T) = Unit
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.fir.kt
new file mode 100644
index 00000000000..f8290772eae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/labeledDelegatedExpression.fir.kt
@@ -0,0 +1,11 @@
+import kotlin.reflect.KProperty
+
+class A3 {
+    val a: String by l@ MyProperty()
+
+    class MyProperty<T> {}
+
+    operator fun <T> MyProperty<T>.getValue(thisRef: Any?, desc: KProperty<*>): T {
+        throw Exception("$thisRef $desc")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/manyIncompleteCandidates.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/manyIncompleteCandidates.fir.kt
new file mode 100644
index 00000000000..8f2adfea2c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/manyIncompleteCandidates.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// FILE: main.kt
+package test
+
+import first.*
+import second.*
+
+val a12 by A()
+
+// FILE: first.kt
+package first
+
+import kotlin.reflect.KProperty
+
+class A
+
+public operator fun <T> A.getValue(thisRef: Any?, property: KProperty<*>): T = null!!
+
+
+// FILE: second.kt
+package second
+
+import first.A
+import kotlin.reflect.KProperty
+
+public operator fun <T> A.getValue(thisRef: Any?, property: KProperty<*>): T = null!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/noErrorsForImplicitConstraints.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/noErrorsForImplicitConstraints.fir.kt
new file mode 100644
index 00000000000..3e58fc32755
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/noErrorsForImplicitConstraints.fir.kt
@@ -0,0 +1,45 @@
+// !WITH_NEW_INFERENCE
+package foo
+
+import kotlin.reflect.KProperty
+
+class A {
+    var a5: String by MyProperty1()
+    var b5: String by getMyProperty1()
+}
+
+fun <A, B> getMyProperty1() = MyProperty1<A, B>()
+
+class MyProperty1<T, R> {
+
+    operator fun getValue(thisRef: R, desc: KProperty<*>): T {
+        throw Exception()
+    }
+
+    operator fun setValue(i: Int, j: Any, k: Int) {
+        println("set")
+    }
+}
+
+// -----------------
+
+class B {
+    var a5: String by MyProperty2()
+    var b5: String by getMyProperty2()
+}
+
+fun <A, B> getMyProperty2() = MyProperty2<A, B>()
+
+class MyProperty2<T, R> {
+
+    operator fun getValue(thisRef: R, desc: KProperty<*>): T {
+        throw Exception()
+    }
+
+    operator fun setValue(i: Int) {
+        println("set")
+    }
+}
+
+// -----------------
+fun println(a: Any?) = a
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/noExpectedTypeForSupertypeConstraint.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/noExpectedTypeForSupertypeConstraint.fir.kt
new file mode 100644
index 00000000000..d06461aa5d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/noExpectedTypeForSupertypeConstraint.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+import kotlin.reflect.KProperty
+
+class A {
+    var a by MyProperty()
+}
+
+class MyProperty<T, R> {
+
+    operator fun getValue(thisRef: R, desc: KProperty<*>): T {
+        throw Exception("$thisRef $desc")
+    }
+
+    operator fun setValue(thisRef: R, desc: KProperty<*>, t: T) {
+        throw Exception("$thisRef $desc $t")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/resultTypeOfLambdaForConventionMethods.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/resultTypeOfLambdaForConventionMethods.fir.kt
new file mode 100644
index 00000000000..0e4b41d5ec0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/resultTypeOfLambdaForConventionMethods.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A<E>
+class B<E, F>
+
+fun <K, V> A<K>.toB(f: (V) -> K, g: (K) -> V): B<K, V> = B()
+
+operator fun <T1, E1> B<T1, E1>.getValue(o: Any, desc: KProperty<*>): E1 = TODO()
+operator fun <T2, E2> B<T2, E2>.setValue(o: Any, desc: KProperty<*>, value: E2) {}
+
+val q = A<String>()
+
+class Test {
+    var prop by q.toB({ "abc" }, { "cde" })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/typeOfLazyDelegatedPropertyWithObject.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/typeOfLazyDelegatedPropertyWithObject.fir.kt
new file mode 100644
index 00000000000..5cc2c1fec01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/typeOfLazyDelegatedPropertyWithObject.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val b: First by lazy {
+    object : First {   }
+}
+
+private val withoutType by lazy {
+    object : First { }
+}
+
+private val withTwoSupertypes by lazy {
+    object : First, Second { }
+}
+
+class A<T> {
+    val a: First by lazy {
+        object : First { }
+    }
+}
+
+interface First
+interface Second
+
+fun <T> lazy(initializer: () -> T): Lazy<T> = TODO()
+interface Lazy<out T> {
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): T = TODO()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/useCompleterWithoutExpectedType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/useCompleterWithoutExpectedType.fir.kt
new file mode 100644
index 00000000000..684cd8878f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/useCompleterWithoutExpectedType.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+import kotlin.reflect.KProperty
+
+class A {
+    val a by MyProperty()
+
+    fun test() {
+        checkSubtype<Int>(a)
+    }
+}
+
+class MyProperty<R> {
+    operator fun getValue(thisRef: R, desc: KProperty<*>): Int = throw Exception("$thisRef $desc")
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/useExpectedType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/useExpectedType.fir.kt
new file mode 100644
index 00000000000..2b4955d7f04
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/useExpectedType.fir.kt
@@ -0,0 +1,76 @@
+package foo
+
+import kotlin.reflect.KProperty
+
+class A1 {
+    var a1: String by MyProperty1()
+    var b1: String by getMyProperty1()
+}
+
+var c1: String by getMyProperty1()
+var d1: String by MyProperty1()
+
+fun <A, B> getMyProperty1() = MyProperty1<A, B>()
+
+class MyProperty1<R, T> {
+
+    operator fun getValue(thisRef: R, desc: KProperty<*>): T {
+        println("get $thisRef ${desc.name}")
+        throw Exception()
+    }
+
+    operator fun setValue(thisRef: R, desc: KProperty<*>, value: T) {
+        println("set $thisRef ${desc.name} $value")
+    }
+}
+
+//--------------------------
+
+class A2 {
+    var a2: String by MyProperty2()
+    var b2: String by getMyProperty2()
+}
+
+var c2: String by getMyProperty2()
+var d2: String by MyProperty2()
+
+fun <A> getMyProperty2() = MyProperty2<A>()
+
+class MyProperty2<T> {
+
+    operator fun getValue(thisRef: Any?, desc: KProperty<*>): T {
+        println("get $thisRef ${desc.name}")
+        throw Exception()
+    }
+
+    operator fun setValue(thisRef: Any?, desc: KProperty<*>, value: T) {
+        println("set $thisRef ${desc.name} $value")
+    }
+}
+
+//--------------------------
+
+class A3 {
+    var a3: String by MyProperty3()
+    var b3: String by getMyProperty3()
+}
+
+var c3: String by getMyProperty3()
+var d3: String by MyProperty3()
+
+fun <A> getMyProperty3() = MyProperty3<A>()
+
+class MyProperty3<T> {
+
+    operator fun getValue(thisRef: T, desc: KProperty<*>): String {
+        println("get $thisRef ${desc.name}")
+        return ""
+    }
+
+    operator fun setValue(thisRef: Any?, desc: KProperty<*>, value: T) {
+        println("set $thisRef ${desc.name} $value")
+    }
+}
+
+//--------------------------
+fun println(a: Any?) = a
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/inference/useExpectedTypeForVal.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/inference/useExpectedTypeForVal.fir.kt
new file mode 100644
index 00000000000..2a4e6fdd94a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/inference/useExpectedTypeForVal.fir.kt
@@ -0,0 +1,64 @@
+package foo
+
+import kotlin.reflect.KProperty
+
+class A1 {
+    val a1: String by MyProperty1()
+    val b1: String by getMyProperty1()
+}
+
+val c1: String by getMyProperty1()
+val d1: String by MyProperty1()
+
+fun <A, B> getMyProperty1() = MyProperty1<A, B>()
+
+class MyProperty1<R, T> {
+
+    operator fun getValue(thisRef: R, desc: KProperty<*>): T {
+        println("get $thisRef ${desc.name}")
+        throw Exception()
+    }
+}
+
+//--------------------------
+
+class A2 {
+    val a2: String by MyProperty2()
+    val b2: String by getMyProperty2()
+}
+
+val c2: String by getMyProperty2()
+val d2: String by MyProperty2()
+
+fun <A> getMyProperty2() = MyProperty2<A>()
+
+class MyProperty2<T> {
+
+    operator fun getValue(thisRef: Any?, desc: KProperty<*>): T {
+        println("get $thisRef ${desc.name}")
+        throw Exception()
+    }
+}
+
+//--------------------------
+
+class A3 {
+    val a3: String by MyProperty3()
+    val b3: String by getMyProperty3()
+}
+
+val c3: String by getMyProperty3()
+val d3: String by MyProperty3()
+
+fun <A> getMyProperty3() = MyProperty3<A>()
+
+class MyProperty3<T> {
+
+    operator fun getValue(thisRef: T, desc: KProperty<*>): String {
+        println("get $thisRef ${desc.name}")
+        return ""
+    }
+}
+
+//--------------------------
+fun println(a: Any?) = a
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/kt4640.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/kt4640.fir.kt
new file mode 100644
index 00000000000..dbfc1239d50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/kt4640.fir.kt
@@ -0,0 +1,11 @@
+//KT-4640 "Trace is erased after resolution completion" exception
+
+class ValueWrapper()
+{
+    var backingValue: Int = 0
+
+    fun getValue() = backingValue
+    fun setValue(v: Int) { backingValue = v }
+}
+
+val foo by ValueWrapper()
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/localVariable.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/localVariable.fir.kt
new file mode 100644
index 00000000000..4816a3d23d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/localVariable.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+import kotlin.reflect.KProperty
+
+class Local {
+    fun foo() {
+        val a: Int by Delegate()
+    }
+}
+
+class Delegate {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int {
+        return 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/localWithSmartCast.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/localWithSmartCast.fir.kt
new file mode 100644
index 00000000000..fe1a2320bf8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/localWithSmartCast.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+interface A {
+    operator fun getValue(x: Any?, y: Any?): Any?
+}
+
+interface B : A {
+    override fun getValue(x: Any?, y: Any?): Int
+}
+
+fun test(a: A) {
+    if (a is B) {
+        val x: Int by a
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/missedGetter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/missedGetter.fir.kt
new file mode 100644
index 00000000000..34e79520b60
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/missedGetter.fir.kt
@@ -0,0 +1,3 @@
+val a: Int by A()
+
+class A
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/missedSetter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/missedSetter.fir.kt
new file mode 100644
index 00000000000..f0e5d03622b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/missedSetter.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+var a: Int by A()
+
+class A {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int {
+      return 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/nonDefaultAccessors.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/nonDefaultAccessors.fir.kt
new file mode 100644
index 00000000000..bc1fa1e3ab4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/nonDefaultAccessors.fir.kt
@@ -0,0 +1,12 @@
+// KT-11809 Assertion error when delegated property has getter
+
+class A {
+    val p1 by this
+        get
+
+    var p2 by this
+        get() = ""
+
+    operator fun getValue(a: Any?, p: Any?) = ""
+    operator fun setValue(a: Any?, p: Any?, v: Any?) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/propertyDefferedType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/propertyDefferedType.fir.kt
new file mode 100644
index 00000000000..2ff3633fde0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/propertyDefferedType.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// NI_EXPECTED_FILE
+
+import kotlin.reflect.KProperty
+
+class B {
+    val c by <!INAPPLICABLE_CANDIDATE!>Delegate<!>(<!UNRESOLVED_REFERENCE!>ag<!>)
+}
+
+class Delegate<T: Any>(val init: T) {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int = null!!
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/commonCaseForInference.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/commonCaseForInference.fir.kt
new file mode 100644
index 00000000000..1da5044c59f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/commonCaseForInference.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object CommonCase {
+    interface Fas<D, E, R>
+
+    fun <D, E, R> delegate() : Fas<D, E, R> = TODO()
+
+    operator fun <D, E, R> Fas<D, E, R>.provideDelegate(host: D, p: Any?): Fas<D, E, R> = TODO()
+    operator fun <D, E, R> Fas<D, E, R>.getValue(receiver: E, p: Any?): R = TODO()
+
+    val Long.test1: String by delegate() // common test, not working because of Inference1
+    val Long.test2: String by delegate<CommonCase, Long, String>() // should work
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/genericProvideDelegate.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/genericProvideDelegate.fir.kt
new file mode 100644
index 00000000000..5ccafeeeac3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/genericProvideDelegate.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Cell<out V>(val value: V)
+
+class GenericDelegate<V>(val value: V)
+
+operator fun <T> T.provideDelegate(a: Any?, p: Any?) = GenericDelegate(this)
+
+operator fun <W> GenericDelegate<W>.getValue(a: Any?, p: Any?) = Cell(value)
+
+val test1: Cell<String> by "OK"
+val test2: Cell<Any> by "OK"
+val test3 by "OK"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver1.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver1.fir.kt
new file mode 100644
index 00000000000..03a654b3bac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver1.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object T1 {
+    operator fun Int.provideDelegate(host: T1, p: Any): Long = 2
+    operator fun Long.getValue(receiver: String, p: Any): Double = 1.0
+
+    val String.test1 by 1
+    val test2 by 1
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver2.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver2.fir.kt
new file mode 100644
index 00000000000..550fd8ef522
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver2.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object T2 {
+    interface Foo<T>
+
+    fun <T> delegate(): Foo<T> = TODO()
+
+    operator fun <T> Foo<T>.provideDelegate(host: T2, p: Any?): Foo<T> = TODO()
+    operator fun <T> Foo<T>.getValue(receiver: String, p: Any?): T = TODO()
+
+    val String.test1: String by delegate()
+    val test2: String by delegate()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver3.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver3.fir.kt
new file mode 100644
index 00000000000..724f8ffddad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/hostAndReceiver3.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object T3 {
+    interface Foo<T>
+
+    fun <T> delegate(): Foo<T> = TODO()
+
+    operator fun <T> Foo<T>.provideDelegate(host: T3, p: Any?): Foo<T> = TODO()
+    operator fun <T> Foo<T>.getValue(receiver: T3, p: Any?): T = TODO()
+
+    val test1: String by delegate()
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/inferenceFromReceiver1.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/inferenceFromReceiver1.fir.kt
new file mode 100644
index 00000000000..492602db86f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/inferenceFromReceiver1.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Inference1 {
+    interface Foo<T>
+
+    fun <T> delegate(): Foo<T> = TODO()
+
+    operator fun <T> Foo<T>.getValue(receiver: T, p: Any?): String = TODO()
+
+    // not working because resulting descriptor for getValue contains type `???` instead of `T`
+    val test1: String by delegate()
+
+    val test2: String by delegate<Inference1>()
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/inferenceFromReceiver2.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/inferenceFromReceiver2.fir.kt
new file mode 100644
index 00000000000..ab1e797532d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/inferenceFromReceiver2.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Inference2 {
+    interface Foo<T>
+
+    fun <T> delegate(): Foo<T> = TODO()
+
+    operator fun <T> Foo<T>.provideDelegate(host: T, p: Any?): Foo<T> = TODO()
+    operator fun <T> Foo<T>.getValue(receiver: Inference2, p: Any?): String = TODO()
+
+    val test1: String by delegate() // same story like in Inference1
+    val test2: String by delegate<Inference2>()
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/localDelegatedProperty.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/localDelegatedProperty.fir.kt
new file mode 100644
index 00000000000..59e33c206a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/localDelegatedProperty.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+operator fun String.provideDelegate(a: Any?, p: KProperty<*>) = this
+operator fun String.getValue(a: Any?, p: KProperty<*>) = this
+
+fun test(): String {
+    val result by "OK"
+    return result
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/noOperatorModifierOnProvideDelegate.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/noOperatorModifierOnProvideDelegate.fir.kt
new file mode 100644
index 00000000000..5f1e4692894
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/noOperatorModifierOnProvideDelegate.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class StringDelegate(val s: String) {
+    operator fun getValue(a: Any?, p: KProperty<*>): Int = 42
+}
+
+// NB no operator
+fun String.provideDelegate(a: Any?, p: KProperty<*>) = StringDelegate(this)
+
+operator fun String.getValue(a: Any?, p: KProperty<*>) = this
+
+val test1: String by "OK"
+val test2: Int by "OK"
+val test3 by "OK"
+
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/overloadResolutionForSeveralProvideDelegates.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/overloadResolutionForSeveralProvideDelegates.fir.kt
new file mode 100644
index 00000000000..ef9c64db88c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/overloadResolutionForSeveralProvideDelegates.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+import kotlin.reflect.KProperty
+
+object Foo
+object Bar
+object Baz
+
+operator fun Foo.provideDelegate(receiver: Any?, property: KProperty<*>) = this
+operator fun Bar.provideDelegate(receiver: Any?, property: KProperty<*>) = this
+
+operator fun Foo.getValue(nothing: Any?, property: KProperty<*>): Any = TODO()
+operator fun Bar.getValue(nothing: Any?, property: KProperty<*>): Any = TODO()
+operator fun Baz.getValue(nothing: Any?, property: KProperty<*>): Any = TODO()
+
+fun test() {
+    val bar by Baz
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/provideDelegateOperatorDeclaration.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/provideDelegateOperatorDeclaration.fir.kt
new file mode 100644
index 00000000000..1bcc06edadb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/provideDelegateOperatorDeclaration.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+operator fun provideDelegate(x: Any?, p: KProperty<*>) {}
+
+operator fun Any.provideDelegate(x: Any?, p: KProperty<*>) {}
+
+operator fun Any.provideDelegate(x: Any?, p: Any) {}
+
+operator fun Any.provideDelegate(x: Any?, p: Int) {}
+
+class Host1 {
+    operator fun provideDelegate(x: Any?, p: KProperty<*>) {}
+}
+
+class Host2 {
+    operator fun Any.provideDelegate(x: Any?, p: KProperty<*>) {}
+}
+
+class Host3 {
+    operator fun provideDelegate(x: Any?, p: KProperty<*>, foo: Int) {}
+}
+
+class Host4 {
+    operator fun provideDelegate(x: Any?, p: KProperty<*>, foo: Int = 0) {}
+}
+
+class Host5 {
+    operator fun provideDelegate(x: Any?, p: KProperty<*>, vararg foo: Int) {}
+}
+
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/setValue.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/setValue.fir.kt
new file mode 100644
index 00000000000..03d0eae31be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/setValue.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Delegate<T>
+
+operator fun Delegate<*>.getValue(receiver: Any?, p: Any): String = ""
+operator fun <T> Delegate<T>.setValue(receiver: Any?, p: Any, value: T) {}
+
+operator fun <T> String.provideDelegate(receiver: Any?, p: Any) = Delegate<T>()
+
+var test1: String by Delegate()
+var test2: String by Delegate<String>()
+
+var test3: String by "OK"
+
+var test4: String by "OK".provideDelegate(null, "")
+var test5: String by "OK".provideDelegate<String>(null, "")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/simpleProvideDelegate.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/simpleProvideDelegate.fir.kt
new file mode 100644
index 00000000000..313f52e12ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/simpleProvideDelegate.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+operator fun String.provideDelegate(a: Any?, p: KProperty<*>) = this
+operator fun String.getValue(a: Any?, p: KProperty<*>) = this
+
+val test1: String by "OK"
+
+val test2 by "OK"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/unsupportedOperatorProvideDelegate.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/unsupportedOperatorProvideDelegate.fir.kt
new file mode 100644
index 00000000000..cd1410a8fc1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/provideDelegate/unsupportedOperatorProvideDelegate.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !LANGUAGE: -OperatorProvideDelegate
+
+class WrongDelegate(val x: Int) {
+    operator fun getValue(thisRef: Any?, prop: Any): Int = x
+}
+
+operator fun String.provideDelegate(thisRef: Any?, prop: Any) = WrongDelegate(this.length)
+
+operator fun String.getValue(thisRef: Any?, prop: Any) = this
+
+val test1: String by "OK"
+val test2: Int by "OK"
+val test3 by "OK"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/recursiveType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/recursiveType.fir.kt
new file mode 100644
index 00000000000..36cb8a7c3cd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/recursiveType.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// NI_EXPECTED_FILE
+
+import kotlin.reflect.KProperty
+
+val a by a
+
+val b by Delegate(b)
+
+val c by d
+val d by c
+
+class Delegate(i: Int) {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/redundantGetter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/redundantGetter.fir.kt
new file mode 100644
index 00000000000..3749eb07218
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/redundantGetter.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val a: Int by Delegate()
+  get() = 1
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/redundantSetter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/redundantSetter.fir.kt
new file mode 100644
index 00000000000..a7009e50fa9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/redundantSetter.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+var a: Int by Delegate()
+  get() = 1
+  set(i) {}
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+
+  operator fun setValue(t: Any?, p: KProperty<*>, i: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/setterThisTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/setterThisTypeMismatch.fir.kt
new file mode 100644
index 00000000000..8a56c046275
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/setterThisTypeMismatch.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class D {
+  var c: Int by Delegate()
+}
+
+var cTopLevel: Int by Delegate()
+
+class A
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+  operator fun setValue(t: A, p: KProperty<*>, i: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/setterWithSupertype.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/setterWithSupertype.fir.kt
new file mode 100644
index 00000000000..694a5ca0436
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/setterWithSupertype.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+open class Base
+class Derived: Base()
+
+var a: Derived by A()
+
+class A {
+  operator fun getValue(t: Any?, p: KProperty<*>): Derived {
+    return Derived()
+  }
+
+  operator fun setValue(t: Any?, p: KProperty<*>, i: Base) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/severalReceivers.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/severalReceivers.fir.kt
new file mode 100644
index 00000000000..f1864d532dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/severalReceivers.fir.kt
@@ -0,0 +1,13 @@
+import kotlin.reflect.KProperty
+
+class A
+
+object Delegate {
+    operator fun getValue(state: A, desc: KProperty<*>): Int  = 0
+    operator fun setValue(state: A, desc: KProperty<*>, value: Int) {}
+}
+
+open class B {
+    val A.foo: Int by Delegate
+    var A.bar: Int by Delegate
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/thisInDelegate.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/thisInDelegate.fir.kt
new file mode 100644
index 00000000000..86c404b813b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/thisInDelegate.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val Int.a by Delegate(this)
+
+class A {
+  val Int.a by <!INAPPLICABLE_CANDIDATE!>Delegate<!>(this)
+}
+
+class Delegate(i: Int) {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/thisOfAnyType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/thisOfAnyType.fir.kt
new file mode 100644
index 00000000000..04ef269bb5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/thisOfAnyType.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A {
+  var a: Int by Delegate()
+}
+
+var aTopLevel: Int by Delegate()
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+  operator fun setValue(t: Any?, p: KProperty<*>, a: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/thisOfNothingNullableType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/thisOfNothingNullableType.fir.kt
new file mode 100644
index 00000000000..9a35ad515a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/thisOfNothingNullableType.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+import kotlin.reflect.KProperty
+
+class A {
+  var a: Int by Delegate()
+}
+
+var aTopLevel: Int by Delegate()
+
+class Delegate {
+  operator fun getValue(t: Nothing?, p: KProperty<*>): Int {
+    return 1
+  }
+  operator fun setValue(t: Nothing?, p: KProperty<*>, a: Int) {
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/thisOfNothingType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/thisOfNothingType.fir.kt
new file mode 100644
index 00000000000..04161d13bc0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/thisOfNothingType.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+import kotlin.reflect.KProperty
+
+class A {
+  var a: Int by Delegate()
+}
+
+var aTopLevel: Int by Delegate()
+
+class Delegate {
+  fun getValue(t: Nothing, p: KProperty<*>): Int {
+    return 1
+  }
+  fun setValue(t: Nothing, p: KProperty<*>, a: Int) {
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/twoGetMethods.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/twoGetMethods.fir.kt
new file mode 100644
index 00000000000..5963ce7fcc7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/twoGetMethods.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A {
+    val c: Int by Delegate()
+}
+
+class Delegate {
+    fun getValue(t: Int, p: KProperty<*>): Int {
+        return 1
+    }
+
+    fun getValue(t: String, p: KProperty<*>): Int {
+        return 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForGetReturnType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForGetReturnType.fir.kt
new file mode 100644
index 00000000000..86f995861b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForGetReturnType.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+val c: Int by Delegate()
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): String {
+    return ""
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForGetWithGeneric.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForGetWithGeneric.fir.kt
new file mode 100644
index 00000000000..4c101ed1aef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForGetWithGeneric.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A
+
+class B {
+  val b: Int by Delegate<A>()
+}
+
+val bTopLevel: Int by Delegate<A>()
+
+class C {
+  val c: Int by Delegate<C>()
+}
+
+val cTopLevel: Int by Delegate<Nothing?>()
+
+class Delegate<T> {
+  operator fun getValue(t: T, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForSetParameter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForSetParameter.fir.kt
new file mode 100644
index 00000000000..c7001296a54
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForSetParameter.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A {
+  var a: Int by Delegate()
+}
+
+var aTopLevel: Int by Delegate()
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+  operator fun setValue(t: Any?, p: KProperty<*>, i: String) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForThisGetParameter.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForThisGetParameter.fir.kt
new file mode 100644
index 00000000000..2b5712dd009
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/typeMismatchForThisGetParameter.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+import kotlin.reflect.KProperty
+
+class B {
+  val b: Int by Delegate()
+}
+
+val bTopLevel: Int by Delegate()
+
+class A
+
+class Delegate {
+  fun getValue(t: A, p: KProperty<*>): Int {
+    return 1
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/wrongCountOfParametersInGet.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/wrongCountOfParametersInGet.fir.kt
new file mode 100644
index 00000000000..3feab5ec632
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/wrongCountOfParametersInGet.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A {
+  val a: Int by Delegate()
+}
+
+val aTopLevel: Int by Delegate()
+
+class Delegate {
+  fun getValue(t: Any?, p: KProperty<*>, a: Int): Int {
+    return a
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/wrongCountOfParametersInSet.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/wrongCountOfParametersInSet.fir.kt
new file mode 100644
index 00000000000..747b8a09c8d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/wrongCountOfParametersInSet.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A {
+  var a: Int by Delegate()
+}
+
+var aTopLevel: Int by Delegate()
+
+class Delegate {
+  operator fun getValue(t: Any?, p: KProperty<*>): Int {
+    return 1
+  }
+
+  operator fun setValue(t: Any?, p: KProperty<*>, a: Int, c: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/delegatedProperty/wrongSetterReturnType.fir.kt b/compiler/testData/diagnostics/tests/delegatedProperty/wrongSetterReturnType.fir.kt
new file mode 100644
index 00000000000..656d940c014
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegatedProperty/wrongSetterReturnType.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+var b: Int by Delegate()
+
+class Delegate {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int {
+      return 1
+    }
+
+    operator fun setValue(t: Any?, p: KProperty<*>, i: Int): Int {
+      return i
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/DelegationAndOverriding.fir.kt b/compiler/testData/diagnostics/tests/delegation/DelegationAndOverriding.fir.kt
new file mode 100644
index 00000000000..0f8abd5ae75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/DelegationAndOverriding.fir.kt
@@ -0,0 +1,38 @@
+package override
+
+interface T {
+    fun foo()
+    val v : Int
+}
+
+open class Br(t : T) : T {
+
+}
+
+class Br3(t : T) : Br(t) {
+
+}
+
+open class Br1(t : T) : T by t {
+
+}
+
+class Br2(t : T) : Br1(t) {
+
+}
+
+interface G<T> {
+    fun foo(t : T) : T
+}
+
+class GC() : G<Int> {
+
+}
+
+open class GC1(g : G<Int>) : G<Int> by g {
+
+}
+
+open class GC2(g : G<Int>) : GC1(g) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/DelegationExpectedType.fir.kt b/compiler/testData/diagnostics/tests/delegation/DelegationExpectedType.fir.kt
new file mode 100644
index 00000000000..3a14bea8dbe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/DelegationExpectedType.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A<T> {
+    fun foo(): Int
+}
+
+class AImpl<T>: A<T> {
+    override fun foo() = 42
+}
+
+class B : A<Int> by AImpl()
+
+fun <T> bar(): A<T> = AImpl()
+
+class C : A<Int> by bar()
+
+fun <T> baz(f: (T) -> T): A<T> = AImpl()
+
+class D : A<Int> by baz({ it + 1 })
+
+fun <T> boo(t: T): A<T> = AImpl()
+
+class E : A<Int> by boo("")
+
+class F : A<Int> by AImpl<String>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/DelegationNotTotrait.fir.kt b/compiler/testData/diagnostics/tests/delegation/DelegationNotTotrait.fir.kt
new file mode 100644
index 00000000000..a2be1fa6abc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/DelegationNotTotrait.fir.kt
@@ -0,0 +1,15 @@
+open class Foo() {
+
+}
+
+class Barrr() : Foo by Foo() {}
+
+interface T {}
+
+class Br(t : T) : T by t {}
+
+open enum class EN() {
+  A
+}
+
+class Test2(e : EN) : EN by e {}
diff --git a/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.fir.kt b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.fir.kt
new file mode 100644
index 00000000000..07044ecce1d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.fir.kt
@@ -0,0 +1,4 @@
+// JAVAC_EXPECTED_FILE
+class TestIface(r : Runnable) : Runnable by r {}
+
+class TestObject(o : Object) : Object by o {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/Delegation_ClashingFunctions.fir.kt b/compiler/testData/diagnostics/tests/delegation/Delegation_ClashingFunctions.fir.kt
new file mode 100644
index 00000000000..075ec0d7e46
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/Delegation_ClashingFunctions.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -CONFLICTING_JVM_DECLARATIONS
+interface One {
+    public fun foo(): Any?
+}
+interface Two {
+    public fun foo(): String?
+}
+
+interface Three {
+    public fun foo(): String
+}
+
+class Test123(val v1: One, val v2: Two, val v3: Three) : One by v1, Two by v2, Three by v3 { }
+class Test132(val v1: One, val v2: Two, val v3: Three) : One by v1, Three by v3, Two by v2 { }
+class Test312(val v1: One, val v2: Two, val v3: Three) : Three by v3, One by v1, Two by v2 { }
+class Test321(val v1: One, val v2: Two, val v3: Three) : Three by v3, Two by v2, One by v1 { }
+class Test231(val v1: One, val v2: Two, val v3: Three) : Two by v2, Three by v3, One by v1 { }
+class Test213(val v1: One, val v2: Two, val v3: Three) : Two by v2, One by v1, Three by v3 { }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/Delegation_Hierarchy.fir.kt b/compiler/testData/diagnostics/tests/delegation/Delegation_Hierarchy.fir.kt
new file mode 100644
index 00000000000..a92b0861c9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/Delegation_Hierarchy.fir.kt
@@ -0,0 +1,12 @@
+interface A {
+    fun foo() {}
+}
+
+open class B(a: A) : A by a
+
+class C(a: A): B(a), A {
+}
+
+fun b(c: C) {
+    c.foo();
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/Delegation_MultipleDelegates.fir.kt b/compiler/testData/diagnostics/tests/delegation/Delegation_MultipleDelegates.fir.kt
new file mode 100644
index 00000000000..22c4949bf8d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/Delegation_MultipleDelegates.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -CONFLICTING_JVM_DECLARATIONS
+interface One {
+  public open fun foo() : Int
+  private fun boo() = 10
+}
+interface Two {
+  public open fun foo() : Int
+}
+
+interface OneImpl : One {
+  public override fun foo() = 1
+}
+interface TwoImpl : Two {
+  public override fun foo() = 2
+}
+
+class Test1() : TwoImpl, OneImpl {}
+class Test2(a : One) : One by a, Two {}
+class Test3(a : One, b : Two) : Two by b, One by a {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/Delegation_ScopeInitializationOrder.fir.kt b/compiler/testData/diagnostics/tests/delegation/Delegation_ScopeInitializationOrder.fir.kt
new file mode 100644
index 00000000000..269d5360436
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/Delegation_ScopeInitializationOrder.fir.kt
@@ -0,0 +1,10 @@
+interface A {
+  fun foo() {}
+}
+
+interface B : A {}
+
+class C(b : B) : B by b {
+
+}
+
diff --git a/compiler/testData/diagnostics/tests/delegation/clashes/finalMemberOverridden.fir.kt b/compiler/testData/diagnostics/tests/delegation/clashes/finalMemberOverridden.fir.kt
new file mode 100644
index 00000000000..e22d9bc2926
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/clashes/finalMemberOverridden.fir.kt
@@ -0,0 +1,56 @@
+// !WITH_NEW_INFERENCE
+open class Final {
+    fun foo() {}
+    val bar: Int = 0
+    var qux: Int = 0
+}
+
+open class Derived : Final()
+
+interface IFoo {
+    fun foo()
+}
+
+class CFoo : IFoo {
+    override fun foo() {}
+}
+
+interface IBar {
+    val bar: Int
+}
+
+class CBar : IBar {
+    override val bar: Int get() = 0
+}
+
+interface IQux {
+    val qux: Int
+}
+
+class CQux : IQux {
+    override val qux: Int get() = 0
+}
+
+interface IBarT<T> {
+    val bar: T
+}
+
+class CBarT<T> : IBarT<T> {
+    override val bar: T get() = null!!
+}
+
+class Test1 : Final(), IFoo by CFoo()
+
+class Test2 : Final(), IBar by CBar()
+
+class Test3 : Final(), IQux by CQux()
+
+class Test4 : Derived(), IFoo by CFoo()
+
+class Test5 : Derived(), IBar by CBar()
+
+class Test6 : Derived(), IQux by CQux()
+
+class Test7 : Final(), IBarT<Int> by CBarT<Int>()
+
+class Test8 : Final(), IBarT<Int> by CBar()
diff --git a/compiler/testData/diagnostics/tests/delegation/clashes/propertyTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/delegation/clashes/propertyTypeMismatch.fir.kt
new file mode 100644
index 00000000000..023163cdfec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/clashes/propertyTypeMismatch.fir.kt
@@ -0,0 +1,57 @@
+interface IStr {
+    val foo: String
+}
+
+class CStr : IStr {
+    override val foo: String get() = ""
+}
+
+interface IInt {
+    val foo: Int
+}
+
+class CInt : IInt {
+    override val foo: Int get() = 42
+}
+
+interface IAny {
+    val foo: Any
+}
+
+class CAny : IAny {
+    override val foo: Any get() = null!!
+}
+
+interface IGeneric<T> {
+    val foo: T
+}
+
+class CGeneric<T> : IGeneric<T> {
+    override val foo: T get() = null!!
+}
+
+abstract class Test1 : IStr by CStr(), IInt
+
+abstract class Test2 : IStr, IInt by CInt()
+
+abstract class Test3 : IStr by CStr(), IInt by CInt()
+
+abstract class Test4 : IStr by CStr(), IGeneric<String>
+
+abstract class Test5 : IStr by CStr(), IGeneric<Any>
+
+abstract class Test6 : IStr by CStr(), IGeneric<Int>
+
+abstract class Test7 : IGeneric<String> by CGeneric<String>(), IStr
+
+abstract class Test8 : IGeneric<String> by CGeneric<String>(), IInt
+
+// Can't test right now due to https://youtrack.jetbrains.com/issue/KT-10258
+// abstract class Test9 : IGeneric<String> by CGeneric<String>(), IGeneric<Int>
+
+abstract class Test10 : IInt by CInt(), IStr by CStr(), IAny by CAny()
+
+abstract class Test11 : IInt, IStr by CStr(), IAny by CAny()
+
+abstract class Test12 : IInt, IStr, IAny by CAny()
+
diff --git a/compiler/testData/diagnostics/tests/delegation/clashes/returnTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/delegation/clashes/returnTypeMismatch.fir.kt
new file mode 100644
index 00000000000..1b7454f373f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/clashes/returnTypeMismatch.fir.kt
@@ -0,0 +1,59 @@
+interface IStr {
+    fun foo(): String
+}
+
+class CStr : IStr {
+    override fun foo(): String = ""
+}
+
+interface IInt {
+    fun foo(): Int
+}
+
+class CInt : IInt {
+    override fun foo(): Int = 42
+}
+
+interface IAny {
+    fun foo(): Any
+}
+
+class CAny : IAny {
+    override fun foo(): Any = null!!
+}
+
+interface IGeneric<T> {
+    fun foo(): T
+}
+
+class CGeneric<T> : IGeneric<T> {
+    override fun foo(): T {
+        throw UnsupportedOperationException()
+    }
+}
+
+abstract class Test1 : IStr by CStr(), IInt
+
+abstract class Test2 : IStr, IInt by CInt()
+
+abstract class Test3 : IStr by CStr(), IInt by CInt()
+
+abstract class Test4 : IStr by CStr(), IGeneric<String>
+
+abstract class Test5 : IStr by CStr(), IGeneric<Any>
+
+abstract class Test6 : IStr by CStr(), IGeneric<Int>
+
+abstract class Test7 : IGeneric<String> by CGeneric<String>(), IStr
+
+abstract class Test8 : IGeneric<String> by CGeneric<String>(), IInt
+
+// Can't test due to https://youtrack.jetbrains.com/issue/KT-10258
+// abstract class Test9 : IGeneric<String> by CGeneric<String>(), IGeneric<Int>
+
+abstract class Test10 : IInt by CInt(), IStr by CStr(), IAny by CAny()
+
+abstract class Test11 : IInt, IStr by CStr(), IAny by CAny()
+
+abstract class Test12 : IInt, IStr, IAny by CAny()
+
diff --git a/compiler/testData/diagnostics/tests/delegation/clashes/varOverriddenByVal.fir.kt b/compiler/testData/diagnostics/tests/delegation/clashes/varOverriddenByVal.fir.kt
new file mode 100644
index 00000000000..77def9382cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/clashes/varOverriddenByVal.fir.kt
@@ -0,0 +1,29 @@
+interface IVar {
+    var foo: Int
+}
+
+interface IDerived : IVar
+
+interface IVal {
+    val foo: Int
+}
+
+class CVal : IVal {
+    override val foo: Int get() = 42
+}
+
+interface IValT<T> {
+    val foo: T
+}
+
+class CValT<T> : IValT<T> {
+    override val foo: T get() = null!!
+}
+
+abstract class Test1 : IVar, IVal by CVal()
+
+abstract class Test2 : IVar, IValT<Int> by CValT<Int>()
+
+abstract class Test3 : IDerived, IVal by CVal()
+
+abstract class Test4 : IDerived, IValT<Int> by CValT<Int>()
diff --git a/compiler/testData/diagnostics/tests/delegation/covariantOverrides/fromClass.fir.kt b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/fromClass.fir.kt
new file mode 100644
index 00000000000..b4db71d128a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/fromClass.fir.kt
@@ -0,0 +1,19 @@
+interface IBase1 {
+    fun foo(): Any
+}
+
+open class IDerived1 : IBase1 {
+    override fun foo(): String = "1"
+}
+
+class Broken1(val b: IBase1) : IBase1 by b, IDerived1()
+
+interface IBase2 {
+    val foo: Any
+}
+
+open class IDerived2 : IBase2 {
+    override val foo: String = "2"
+}
+
+class Broken2(val b: IBase2) : IBase2 by b, IDerived2()
diff --git a/compiler/testData/diagnostics/tests/delegation/covariantOverrides/irrelevant.fir.kt b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/irrelevant.fir.kt
new file mode 100644
index 00000000000..a864c7c4a2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/irrelevant.fir.kt
@@ -0,0 +1,19 @@
+interface IBase1 {
+    fun foo(): Any
+}
+
+interface IDerived1 {
+    fun foo(): String
+}
+
+class Broken1(val b: IBase1) : IBase1 by b, IDerived1
+
+interface IBase2 {
+    val foo: Any
+}
+
+interface IDerived2 {
+    val foo: String
+}
+
+class Broken2(val b: IBase2) : IBase2 by b, IDerived2
diff --git a/compiler/testData/diagnostics/tests/delegation/covariantOverrides/kt13952.fir.kt b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/kt13952.fir.kt
new file mode 100644
index 00000000000..127b8af6c69
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/kt13952.fir.kt
@@ -0,0 +1,17 @@
+interface IA {
+    fun foo(): Number
+}
+
+interface IB : IA {
+    override fun foo(): Int
+}
+
+object AImpl : IA {
+    override fun foo() = 42
+}
+
+open class C : IA by AImpl, IB
+
+class D : C() {
+    override fun foo(): Double = 3.14
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/covariantOverrides/simple.fir.kt b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/simple.fir.kt
new file mode 100644
index 00000000000..5dd07749362
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/covariantOverrides/simple.fir.kt
@@ -0,0 +1,19 @@
+interface IBase1 {
+    fun foo(): Any
+}
+
+interface IDerived1 : IBase1 {
+    override fun foo(): String
+}
+
+class Broken1(val b: IBase1) : IBase1 by b, IDerived1
+
+interface IBase2 {
+    val foo: Any
+}
+
+interface IDerived2 : IBase2 {
+    override val foo: String
+}
+
+class Broken2(val b: IBase2) : IBase2 by b, IDerived2
diff --git a/compiler/testData/diagnostics/tests/delegation/kt8154.fir.kt b/compiler/testData/diagnostics/tests/delegation/kt8154.fir.kt
new file mode 100644
index 00000000000..066fef5fa23
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/kt8154.fir.kt
@@ -0,0 +1,11 @@
+interface A<T> {
+    fun foo()
+}
+
+interface B<T> : A<T> {
+    fun bar()
+}
+
+class BImpl<T>(a: A<T>) : B<T>, A<T> by a {
+    override fun bar() { throw UnsupportedOperationException() }
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/abstractOverride.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/abstractOverride.fir.kt
new file mode 100644
index 00000000000..861ec527e6b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/abstractOverride.fir.kt
@@ -0,0 +1,18 @@
+public interface Base {
+    fun test() = "OK"
+}
+
+
+abstract class Impl : Base {
+    override abstract fun test(): String
+}
+
+class Delegate : Base
+
+
+fun box(): String {
+    object : Impl(), Base by Delegate() {
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubType.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubType.fir.kt
new file mode 100644
index 00000000000..930bd45514c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubType.fir.kt
@@ -0,0 +1,19 @@
+public interface Base {
+    fun test() = "OK"
+}
+
+public interface Base2 : Base 
+
+class Delegate : Base2
+
+fun box(): String {
+    object : Base, Base2 by Delegate() {
+
+    }
+
+    object : Base2, Base by Delegate() {
+    
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeProperty.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeProperty.fir.kt
new file mode 100644
index 00000000000..9c55da1c50c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeProperty.fir.kt
@@ -0,0 +1,20 @@
+public interface Base {
+    val test: String
+            get() = "OK"
+}
+
+public interface Base2 : Base 
+
+class Delegate : Base2
+
+fun box(): String {
+    object : Base, Base2 by Delegate() {
+
+    }
+
+    object : Base2, Base by Delegate() {
+    
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverride.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverride.fir.kt
new file mode 100644
index 00000000000..eb7a997f4d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverride.fir.kt
@@ -0,0 +1,19 @@
+public interface Base {
+    fun test() = "OK"
+}
+
+public interface Base2 : Base {
+    override fun test() = "OK2"
+}
+
+class Delegate : Base2
+
+fun box(): String {
+    object : Base, Base2 by Delegate() {
+    }
+
+    object : Base2, Base by Delegate() {
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverrideProperty.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverrideProperty.fir.kt
new file mode 100644
index 00000000000..f11545756b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/delegationToSubTypeWithOverrideProperty.fir.kt
@@ -0,0 +1,26 @@
+public interface Base {
+    var test: String
+        get() = "OK"
+        set(s: String) {
+        }
+}
+
+public interface Base2 : Base {
+    override var test: String
+            get() = "OK2"
+            set(value) {}
+}
+
+class Delegate : Base2 {
+
+}
+
+fun box(): String {
+    object : Base, Base2 by Delegate() {
+    }
+
+    object : Base2, Base by Delegate() {
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/diamond.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/diamond.fir.kt
new file mode 100644
index 00000000000..a493209b585
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/diamond.fir.kt
@@ -0,0 +1,43 @@
+public interface Base {
+    fun test() = "Base"
+}
+
+public interface Base2 : Base {
+    override fun test() = "Base2"
+}
+
+public interface Base3 : Base {
+    override fun test() = "Base3"
+}
+
+class Impl : Base
+
+class Impl2 : Base2
+
+class Impl3 : Base3
+
+class ImplAll : Base, Base2, Base3 {
+    override fun test(): String {
+        return super<Base2>.test()
+    }
+}
+
+fun box(): String {
+    object : Base2, Base3, Base by Impl() {
+
+    }
+
+    object : Base2 by Impl2(), Base3, Base {
+
+    }
+
+    object : Base2, Base3 by Impl3(), Base {
+
+    }
+
+    object : Base2 by Impl2(), Base3 by Impl3(), Base by Impl() {
+
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/explicitOverride.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/explicitOverride.fir.kt
new file mode 100644
index 00000000000..d2bc0a749f0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/explicitOverride.fir.kt
@@ -0,0 +1,18 @@
+public interface Base {
+    fun test() = "OK"
+}
+
+open class Base2 : Base {
+    override fun test() = "OK2"
+}
+
+class Delegate : Base
+
+fun box(): String {
+
+    object : Base2(), Base by Delegate() {
+        override fun test() = "OK"
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/fakeOverrideInTheMiddle.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/fakeOverrideInTheMiddle.fir.kt
new file mode 100644
index 00000000000..185b566065d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/fakeOverrideInTheMiddle.fir.kt
@@ -0,0 +1,13 @@
+interface Base {
+    fun test() = "Base"
+}
+
+class Delegate : Base
+
+abstract class Middle : Base {
+    override fun test() = "MyClass"
+}
+
+abstract class MyClass : Middle()
+
+class A : MyClass(), Base by Delegate()
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/generic.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/generic.fir.kt
new file mode 100644
index 00000000000..fb4fa1e4ee9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/generic.fir.kt
@@ -0,0 +1,14 @@
+public interface Base<T> {
+    fun test(p: T) = "Base"
+}
+
+public interface Derived<Y> : Base<Y>
+
+class Delegate<Z> : Derived<Z>
+
+fun box(): String {
+    object :  Derived<String> by Delegate() {
+    }
+    return "OK"
+}
+
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/sameDelegationInHierarchy.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/sameDelegationInHierarchy.fir.kt
new file mode 100644
index 00000000000..382b104432c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/sameDelegationInHierarchy.fir.kt
@@ -0,0 +1,16 @@
+public interface Base {
+    fun test() = "Base"
+}
+
+class Delegate : Base {
+    override fun test() = "Base"
+}
+
+public open class MyClass : Base by Delegate()
+
+fun box(): String {
+    object : MyClass(), Base by Delegate() {
+    }
+    return "OK"
+}
+
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/sameDelegationInHierarchy2.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/sameDelegationInHierarchy2.fir.kt
new file mode 100644
index 00000000000..9807192268f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/sameDelegationInHierarchy2.fir.kt
@@ -0,0 +1,21 @@
+public interface Base {
+    fun test() = "Base"
+}
+
+public interface Derived : Base {
+    override fun test() = "Derived"
+}
+
+
+class Delegate : Derived {
+    override fun test() = "Delegate"
+}
+
+public open class MyClass : Base by Delegate()
+
+fun box(): String {
+    object : MyClass(), Derived by Delegate() {
+    }
+    return "OK"
+}
+
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/severalDelegates.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/severalDelegates.fir.kt
new file mode 100644
index 00000000000..06098cc48fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/severalDelegates.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+interface Base1 {
+    fun test() = "OK"
+}
+
+interface Base2 {
+    fun test2() = "OK"
+}
+
+
+class Delegate1 : Base1
+
+class Delegate2 : Base2
+
+
+public abstract class MyClass : Base1, Base2 {
+    override fun test(): String {
+        return "Class"
+    }
+
+    override fun test2(): String {
+        return "Class"
+    }
+}
+
+class A : MyClass(), Base1 by Delegate1(), Base1 by Delegate2() {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple.fir.kt
new file mode 100644
index 00000000000..caf2804ed72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simple.fir.kt
@@ -0,0 +1,19 @@
+public interface Base {
+    fun getValue(): String
+
+    fun test() = getValue()
+}
+
+class Delegate : Base {
+    override fun getValue() = "Delegate"
+}
+
+public abstract class MyClass : Base {
+    override fun test(): String {
+        return "Class"
+    }
+}
+
+class A : MyClass(), Base by Delegate() {
+    override fun getValue() = "Delegate"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleNoOverride.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleNoOverride.fir.kt
new file mode 100644
index 00000000000..cacaab043f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleNoOverride.fir.kt
@@ -0,0 +1,15 @@
+interface Base {
+    fun test() = "OK"
+}
+
+open class Base2 : Base
+
+class Delegate : Base
+
+fun box(): String {
+    object : Base2(), Base by Delegate() {
+
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleProp.fir.kt b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleProp.fir.kt
new file mode 100644
index 00000000000..3878b279f00
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/delegation/memberHidesSupertypeOverride/simpleProp.fir.kt
@@ -0,0 +1,17 @@
+public interface Base {
+    val test: String
+        get() = "OK"
+}
+
+open class Delegate : Base {
+    override val test: String
+        get() = "OK"
+}
+
+fun box(): String {
+    object : Delegate(), Base by Delegate() {
+
+    }
+
+    return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/ParenthesizedVariable.fir.kt b/compiler/testData/diagnostics/tests/deparenthesize/ParenthesizedVariable.fir.kt
new file mode 100644
index 00000000000..f8950a03263
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deparenthesize/ParenthesizedVariable.fir.kt
@@ -0,0 +1,3 @@
+fun test() {
+    (d@ val bar = 2)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/annotatedSafeCall.fir.kt b/compiler/testData/diagnostics/tests/deparenthesize/annotatedSafeCall.fir.kt
new file mode 100644
index 00000000000..f5ccb9a914f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deparenthesize/annotatedSafeCall.fir.kt
@@ -0,0 +1,7 @@
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class foo
+
+fun f(s : String?) : Boolean {
+    return (@foo s?.equals("a"))!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/checkDeparenthesizedType.fir.kt b/compiler/testData/diagnostics/tests/deparenthesize/checkDeparenthesizedType.fir.kt
new file mode 100644
index 00000000000..5a4a7138942
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deparenthesize/checkDeparenthesizedType.fir.kt
@@ -0,0 +1,30 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+package m
+
+fun test(i: Int?) {
+    if (i != null) {
+        foo(l1@ i)
+        foo((i))
+        foo(l2@ (i))
+        foo((l3@ i))
+    }
+
+    val a: Int = l4@ ""
+    val b: Int = ("")
+    val c: Int = <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>("")
+    val d: Int = <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Long>("")
+
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(l4@ "")
+    <!INAPPLICABLE_CANDIDATE!>foo<!>((""))
+    foo(<!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(""))
+    foo(<!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Long>(""))
+    
+    use(a, b, c, d)
+}
+
+fun foo(i: Int) = i
+
+fun use(vararg a: Any?) = a
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/labeledSafeCall.fir.kt b/compiler/testData/diagnostics/tests/deparenthesize/labeledSafeCall.fir.kt
new file mode 100644
index 00000000000..e270df0ec1d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deparenthesize/labeledSafeCall.fir.kt
@@ -0,0 +1,3 @@
+fun f(s : String?) : Boolean {
+    return foo@(s?.equals("a"))!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/multiParenthesizedSafeCall.fir.kt b/compiler/testData/diagnostics/tests/deparenthesize/multiParenthesizedSafeCall.fir.kt
new file mode 100644
index 00000000000..209ab44d1a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deparenthesize/multiParenthesizedSafeCall.fir.kt
@@ -0,0 +1,3 @@
+fun f(s : String?) : Boolean {
+    return (((s?.equals("a"))))!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deparenthesize/parenthesizedSafeCall.fir.kt b/compiler/testData/diagnostics/tests/deparenthesize/parenthesizedSafeCall.fir.kt
new file mode 100644
index 00000000000..bab8ed3f1be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deparenthesize/parenthesizedSafeCall.fir.kt
@@ -0,0 +1,3 @@
+fun f(s : String?) : Boolean {
+    return (s?.equals("a"))!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/annotationUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/annotationUsage.fir.kt
new file mode 100644
index 00000000000..8b1d35a1758
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/annotationUsage.fir.kt
@@ -0,0 +1,9 @@
+@Deprecated("text")
+annotation class obsolete()
+
+@Deprecated("text")
+annotation class obsoleteWithParam(val text: String)
+
+@obsolete class Obsolete
+
+@obsoleteWithParam("text") class Obsolete2
diff --git a/compiler/testData/diagnostics/tests/deprecated/classWithCompanionObject.fir.kt b/compiler/testData/diagnostics/tests/deprecated/classWithCompanionObject.fir.kt
new file mode 100644
index 00000000000..4d851d7127a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/classWithCompanionObject.fir.kt
@@ -0,0 +1,8 @@
+class A {
+    @Deprecated("deprecated") companion object
+
+    class B
+}
+
+val x1 = A.B()
+
diff --git a/compiler/testData/diagnostics/tests/deprecated/companionObjectUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/companionObjectUsage.fir.kt
new file mode 100644
index 00000000000..b348132c308
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/companionObjectUsage.fir.kt
@@ -0,0 +1,32 @@
+class Another {
+    @Deprecated("Object")
+    companion object {
+        fun use() {}
+        const val USE = 42
+    }
+}
+
+fun first() {
+    Another.use()
+    Another.Companion.USE
+    Another.USE
+}
+
+fun useCompanion() {
+    val d = Another
+    val x = Another.Companion
+    Another.Companion.use()
+    Another.use()
+}
+
+@Deprecated("Some")
+class Some {
+    companion object {
+        fun use() {}
+    }
+}
+
+fun some() {
+    Some.use()
+    Some.Companion.use()
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/componentUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/componentUsage.fir.kt
new file mode 100644
index 00000000000..a5c9bb6e78e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/componentUsage.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+class Data {
+    @Deprecated("text")
+    operator fun component1(): String = throw Exception()
+    operator fun component2(): String = throw Exception()
+}
+
+fun use() {
+    val (x, y) = Data()
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/deprecatedConstructor.fir.kt b/compiler/testData/diagnostics/tests/deprecated/deprecatedConstructor.fir.kt
new file mode 100644
index 00000000000..9a8d8ec398b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/deprecatedConstructor.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.kt
+class A(s: String) {
+    @Deprecated("")
+    constructor(i: Int) : this(i.toString()) {
+
+    }
+}
+
+// FILE: B.java
+public class B extends A {
+    @Deprecated
+    public B(int i) {
+
+    }
+
+    public B(String s) {
+
+    }
+}
+
+// FILE: C.kt
+class C @Deprecated("") constructor(s: String) {
+}
+
+// FILE: use.kt
+fun use(a: A, b: B, c: C) {
+    A(3)
+    A("")
+    B(3)
+    B("")
+    C("s")
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/deprecatedError.fir.kt b/compiler/testData/diagnostics/tests/deprecated/deprecatedError.fir.kt
new file mode 100644
index 00000000000..c39c8fb5c34
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/deprecatedError.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Deprecated("alas", level = DeprecationLevel.ERROR)
+fun foo() {}
+
+@Deprecated("alas", level = DeprecationLevel.ERROR)
+class C
+
+fun test(c: C) {
+    foo()
+    C()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/deprecatedErrorBuilder.fir.kt b/compiler/testData/diagnostics/tests/deprecated/deprecatedErrorBuilder.fir.kt
new file mode 100644
index 00000000000..05dfbdabb77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/deprecatedErrorBuilder.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class Table
+class Tr
+
+fun table(body: Table.() -> Unit) {}
+fun Table.tr(body: Tr.() -> Unit) {}
+@Deprecated("Don't call me", level = DeprecationLevel.ERROR)
+fun Tr.tr(body: Tr.() -> Unit) {}
+
+fun builderTest() {
+    table {
+        tr {
+            tr {}
+            table {
+                tr {
+                    tr {}
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/deprecatedHidden.fir.kt b/compiler/testData/diagnostics/tests/deprecated/deprecatedHidden.fir.kt
new file mode 100644
index 00000000000..f2449e1448c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/deprecatedHidden.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+@Deprecated("", level = DeprecationLevel.HIDDEN)
+open class Foo
+
+fun test(f: Foo) {
+    f.toString()
+    val g: Foo? = Foo()
+}
+
+class Bar : Foo()
diff --git a/compiler/testData/diagnostics/tests/deprecated/deprecatedInheritance.fir.kt b/compiler/testData/diagnostics/tests/deprecated/deprecatedInheritance.fir.kt
new file mode 100644
index 00000000000..b00759def84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/deprecatedInheritance.fir.kt
@@ -0,0 +1,140 @@
+package foo
+
+interface WarningDeprecated {
+    @Deprecated("", level = DeprecationLevel.WARNING)
+    fun f() {
+
+    }
+}
+
+interface ErrorDeprecated {
+    @Deprecated("", level = DeprecationLevel.ERROR)
+    fun f() {
+
+    }
+}
+
+interface HiddenDeprecated {
+    @Deprecated("", level = DeprecationLevel.HIDDEN)
+    fun f() {
+
+    }
+}
+
+interface NotDeprecated {
+    fun f() {
+
+    }
+}
+
+open class WE : WarningDeprecated, ErrorDeprecated {
+    override fun f() {
+
+    }
+}
+
+open class WH : WarningDeprecated, HiddenDeprecated {
+    override fun f() {
+
+    }
+}
+
+open class EH : ErrorDeprecated, HiddenDeprecated {
+    override fun f() {
+
+    }
+}
+
+open class NW : WarningDeprecated, NotDeprecated {
+    override fun f() {
+
+    }
+}
+
+open class NE : ErrorDeprecated, NotDeprecated {
+    override fun f() {
+
+    }
+}
+
+open class NH : HiddenDeprecated, NotDeprecated {
+    override fun f() {
+
+    }
+}
+
+open class WEH: WarningDeprecated, ErrorDeprecated, HiddenDeprecated {
+    override fun f() {
+
+    }
+}
+
+open class NWEH: NotDeprecated, WarningDeprecated, ErrorDeprecated, HiddenDeprecated {
+    override fun f() {
+
+    }
+}
+
+class WE2: WE()
+
+class NWE2: WE(), NotDeprecated
+
+class NWE3: WE(), NotDeprecated {
+    override fun f() {
+    }
+}
+
+interface E2: ErrorDeprecated
+interface W2: WarningDeprecated
+
+interface EW2: E2, W2 {
+    override fun f() {
+    }
+}
+
+interface HEW2: EW2, HiddenDeprecated {
+    override fun f() {
+    }
+}
+
+interface ExplicitError: HEW2 {
+    @Deprecated("", level = DeprecationLevel.ERROR)
+    override fun f() {
+        super.f()
+    }
+}
+
+fun use(
+        wd: WarningDeprecated, ed: ErrorDeprecated, hd: HiddenDeprecated,
+        we: WE, wh: WH, eh: EH, nw: NW, ne: NE, nh: NH,
+        weh: WEH, nweh: NWEH,
+        we2: WE2, nwe2: NWE2, nwe3: NWE3,
+        e2: E2, w2: W2, ew2: EW2, hew2: HEW2,
+        explicitError: ExplicitError
+) {
+    wd.f()
+    ed.f()
+    hd.f()
+
+    we.f()
+    wh.f()
+    eh.f()
+
+    nw.f()
+    ne.f()
+    nh.f()
+
+    weh.f()
+    nweh.f()
+
+    we2.f()
+    nwe2.f()
+    nwe3.f()
+
+    e2.f()
+    w2.f()
+    ew2.f()
+    hew2.f()
+
+    explicitError.f()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/deprecatedPropertyInheritance.fir.kt b/compiler/testData/diagnostics/tests/deprecated/deprecatedPropertyInheritance.fir.kt
new file mode 100644
index 00000000000..7767cce15ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/deprecatedPropertyInheritance.fir.kt
@@ -0,0 +1,135 @@
+package foo
+
+interface HiddenDeprecated {
+    @Deprecated("", level = DeprecationLevel.HIDDEN)
+    var p: Int
+}
+
+interface NoDeprecation {
+    var p: Int
+}
+
+
+open class WarningDeprecated {
+    @Deprecated("", level = DeprecationLevel.WARNING)
+    open var p: Int = 3
+}
+
+open class ErrorDeprecated {
+    @Deprecated("", level = DeprecationLevel.ERROR)
+    open var p: Int = 3
+}
+
+open class GetterDeprecated {
+    open var p: Int = 3
+        @Deprecated("") get
+}
+
+open class SetterDeprecated {
+    open var p: Int = 3
+        @Deprecated("") set
+}
+
+class WD: WarningDeprecated() {
+    override var p: Int
+        get() = 3
+        set(value) {}
+}
+
+class ED: ErrorDeprecated() {
+    override var p: Int
+        get() = 3
+        set(value) {
+        }
+}
+
+class GD: GetterDeprecated() {
+    override var p: Int
+        get() = 3
+        set(value) {
+        }
+}
+
+class SD: SetterDeprecated() {
+    override var p: Int
+        get() = 3
+        set(value) {
+        }
+}
+
+class SDH: SetterDeprecated(), HiddenDeprecated {
+    override var p: Int
+        get() = 3
+        set(value) {
+        }
+}
+
+class EDH: ErrorDeprecated(), HiddenDeprecated {
+    override var p: Int
+        get() = 3
+        set(value) {
+        }
+}
+
+class NED: ErrorDeprecated(), NoDeprecation {
+    override var p: Int
+        get() = 3
+        set(value) {
+        }
+}
+
+class Diff {
+    @Deprecated("", level = DeprecationLevel.WARNING)
+    var p: Int
+        @Deprecated("", level = DeprecationLevel.ERROR) get() = 3
+        @Deprecated("", level = DeprecationLevel.HIDDEN) set(value) {
+
+        }
+}
+
+fun use(
+        warningDeprecated: WarningDeprecated, errorDeprecated: ErrorDeprecated, setterDeprecated: SetterDeprecated,
+        getterDeprecated: GetterDeprecated, hiddenDeprecated: HiddenDeprecated,
+        wd: WD, ed: ED, gd: GD, sd: SD,
+        sdh: SDH, edh: EDH, ned: NED,
+        diff: Diff
+) {
+    warningDeprecated.p
+    warningDeprecated.p = 1
+
+    errorDeprecated.p
+    errorDeprecated.p = 1
+
+    getterDeprecated.p
+    getterDeprecated.p = 1
+
+    setterDeprecated.p
+    setterDeprecated.p = 1
+
+    hiddenDeprecated.p
+    hiddenDeprecated.p = 1
+
+    wd.p
+    wd.p = 1
+
+    ed.p
+    ed.p = 1
+
+    gd.p
+    gd.p = 1
+
+    sd.p
+    sd.p = 1
+
+    sdh.p
+    sdh.p = 1
+
+    edh.p
+    edh.p = 1
+
+    ned.p
+    ned.p = 1
+
+    diff.p
+    diff.p = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/functionUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/functionUsage.fir.kt
new file mode 100644
index 00000000000..de878244f06
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/functionUsage.fir.kt
@@ -0,0 +1,51 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+import kotlin.reflect.KProperty
+
+class UsefulClass(val param: Int = 2) {
+    operator fun getValue(instance: Any, property: KProperty<*>) : Int = 1
+    operator fun setValue(instance: Any, property: KProperty<*>, value: Int) {}
+
+    @Deprecated("message")
+    fun member() {}
+}
+
+@Deprecated("message")
+fun Obsolete(param: Int = 1): UsefulClass = UsefulClass(param)
+
+class Invocable {
+    @Deprecated("message")
+    operator fun invoke() {}
+}
+
+object InvocableHolder {
+    val invocable = Invocable()
+}
+
+fun invoker() {
+    val invocable = Invocable()
+    invocable()
+    InvocableHolder.invocable()
+}
+
+fun block() {
+    Obsolete()
+    Obsolete(2)
+}
+
+fun expression() = Obsolete()
+
+fun reflection() = ::Obsolete
+fun reflection2() = UsefulClass::member
+
+class Initializer {
+    val x = Obsolete()
+}
+
+@Deprecated("does nothing good")
+fun Any.doNothing() = this.toString()  // "this" should not be marked as deprecated despite it referes to deprecated function
+
+class Delegation {
+    val x by Obsolete()
+    var y by Obsolete()
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/genericConstructorUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/genericConstructorUsage.fir.kt
new file mode 100644
index 00000000000..51c43c5b11c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/genericConstructorUsage.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION, -UNUSED_PARAMETER
+
+open class C<T>() {
+    @Deprecated("")
+    constructor(p: Int) : this(){}
+}
+
+class D : C<String>(1)
diff --git a/compiler/testData/diagnostics/tests/deprecated/hiddenPropertyAccessors.fir.kt b/compiler/testData/diagnostics/tests/deprecated/hiddenPropertyAccessors.fir.kt
new file mode 100644
index 00000000000..1376223dd75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/hiddenPropertyAccessors.fir.kt
@@ -0,0 +1,40 @@
+val v1: String
+    @Deprecated("", level = DeprecationLevel.HIDDEN)
+    get() = ""
+
+@Deprecated("", level = DeprecationLevel.HIDDEN)
+val v2 = ""
+
+var v3: String
+    @Deprecated("", level = DeprecationLevel.HIDDEN)
+    get() = ""
+    set(value) {}
+
+var v4: String
+    get() = ""
+    @Deprecated("", level = DeprecationLevel.HIDDEN)
+    set(value) {}
+
+var v5: String
+    @Deprecated("", level = DeprecationLevel.HIDDEN)
+    get() = ""
+    @Deprecated("", level = DeprecationLevel.HIDDEN)
+    set(value) {}
+
+@Deprecated("", level = DeprecationLevel.HIDDEN)
+var v6: String
+    get() = ""
+    set(value) {}
+
+fun test() {
+    v1
+    v2
+    v3
+    v3 = ""
+    v4
+    v4 = ""
+    v5
+    v5 = ""
+    v6
+    v6 = ""
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/importJavaSamInterface.fir.kt b/compiler/testData/diagnostics/tests/deprecated/importJavaSamInterface.fir.kt
new file mode 100644
index 00000000000..8b28ed7ebfd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/importJavaSamInterface.fir.kt
@@ -0,0 +1,13 @@
+// SKIP_TXT
+// FILE: test/J.java
+
+package test;
+
+@Deprecated
+public interface J {
+    public String foo(int x);
+}
+
+// FILE: K.kt
+
+import test.J
diff --git a/compiler/testData/diagnostics/tests/deprecated/imports.fir.kt b/compiler/testData/diagnostics/tests/deprecated/imports.fir.kt
new file mode 100644
index 00000000000..bd3a686540d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/imports.fir.kt
@@ -0,0 +1,8 @@
+import C as C2
+
+@Deprecated("obsolete")
+class C {
+    fun use() {}
+}
+
+fun useAlias(c : C2) { c.use() }
diff --git a/compiler/testData/diagnostics/tests/deprecated/iteratorUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/iteratorUsage.fir.kt
new file mode 100644
index 00000000000..7f6615b6ab5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/iteratorUsage.fir.kt
@@ -0,0 +1,24 @@
+class Iter {
+    @Deprecated("text")
+    operator fun iterator() : IterIterator = throw Exception()
+
+    class IterIterator {
+        operator fun hasNext(): Boolean = throw UnsupportedOperationException()
+        operator fun next(): String = throw UnsupportedOperationException()
+    }
+}
+
+class Iter2 {
+    operator fun iterator() : Iter2Iterator = throw Exception()
+    class Iter2Iterator {
+        @Deprecated("text")
+        operator fun hasNext(): Boolean = throw UnsupportedOperationException()
+        @Deprecated("text")
+        operator fun next(): String = throw UnsupportedOperationException()
+    }
+}
+
+fun use() {
+    for (x in Iter()) {}
+    for (x in Iter2()) {}
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/javaDeprecated.fir.kt b/compiler/testData/diagnostics/tests/deprecated/javaDeprecated.fir.kt
new file mode 100644
index 00000000000..4206722ba17
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/javaDeprecated.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -NO_VALUE_FOR_PARAMETER
+// FILE: A.java
+
+@Deprecated
+public class A {
+    @Deprecated
+    public String getFoo(String text) {
+        return text;
+    }
+}
+
+// FILE: B.kt
+
+class B(private @property:Deprecated val foo: String) : A() {
+    override fun getFoo(text: String): String = super.getFoo(text + foo)
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/javaDeprecatedInheritance.fir.kt b/compiler/testData/diagnostics/tests/deprecated/javaDeprecatedInheritance.fir.kt
new file mode 100644
index 00000000000..a3cf0deac2e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/javaDeprecatedInheritance.fir.kt
@@ -0,0 +1,53 @@
+// FILE: A.java
+
+public class A {
+
+    @Deprecated
+    public static final String D = "d";
+
+    @Deprecated
+    public void f() {
+        return text;
+    }
+
+    @Deprecated
+    public static void bar() {
+    }
+}
+
+// FILE: B.java
+
+public class B extends A {
+
+    public static final String D = "d";
+
+    @Override
+    public void f() {
+        return text;
+    }
+
+    public static void bar() {
+    }
+}
+
+
+// FILE: C.java
+
+public class C extends A {
+}
+
+// FILE: use.kt
+
+fun use(a: A, b: B, c: C) {
+    a.f()
+    b.f()
+    c.f()
+
+    A.D
+    B.<!AMBIGUITY!>D<!>
+    C.D
+
+    A.bar()
+    B.bar()
+    C.bar()
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/javaDocDeprecated.fir.kt b/compiler/testData/diagnostics/tests/deprecated/javaDocDeprecated.fir.kt
new file mode 100644
index 00000000000..35b7aa0977a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/javaDocDeprecated.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -NO_VALUE_FOR_PARAMETER
+// FILE: A.java
+
+/**
+ * @deprecated
+ */
+public class A {
+    /**
+     * @deprecated
+     */
+    public String getFoo(String text) {
+        return text;
+    }
+}
+
+// FILE: B.kt
+
+class B(private val foo: String) : A() {
+    override fun getFoo(text: String): String = super.getFoo(text + foo)
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/nestedTypesUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/nestedTypesUsage.fir.kt
new file mode 100644
index 00000000000..08721d085ce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/nestedTypesUsage.fir.kt
@@ -0,0 +1,18 @@
+class TopLevel {
+    @Deprecated("Nested")
+    class Nested {
+        companion object {
+            fun use() {}
+
+            class CompanionNested2
+        }
+
+        class Nested2
+    }
+}
+
+fun useNested() {
+    val d = TopLevel.Nested.use()
+    TopLevel.Nested.Nested2()
+    TopLevel.Nested.CompanionNested2()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/objectUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/objectUsage.fir.kt
new file mode 100644
index 00000000000..5cfe5dab560
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/objectUsage.fir.kt
@@ -0,0 +1,9 @@
+@Deprecated("Object")
+object Obsolete {
+    fun use() {}
+}
+
+fun useObject() {
+    Obsolete.use()
+    val x = Obsolete
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/propertyUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/propertyUsage.fir.kt
new file mode 100644
index 00000000000..7620f3c6feb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/propertyUsage.fir.kt
@@ -0,0 +1,66 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+import kotlin.reflect.KProperty
+
+class Delegate() {
+    @Deprecated("text")
+    operator fun getValue(instance: Any, property: KProperty<*>) : Int = 1
+
+    @Deprecated("text")
+    operator fun setValue(instance: Any, property: KProperty<*>, value: Int) {}
+}
+
+class PropertyHolder {
+    @Deprecated("text")
+    val x = 1
+
+    @Deprecated("text")
+    var name = "String"
+
+    val valDelegate by Delegate()
+    var varDelegate by Delegate()
+
+    public val test1: String = ""
+        @Deprecated("val-getter") get
+
+    public var test2: String = ""
+        @Deprecated("var-getter") get
+        @Deprecated("var-setter") set
+
+    public var test3: String = ""
+        @Deprecated("var-getter") get
+        set
+
+    public var test4: String = ""
+        get
+        @Deprecated("var-setter") set
+}
+
+fun PropertyHolder.extFunction() {
+    test2 = "ext"
+    test1
+}
+
+fun fn() {
+    PropertyHolder().test1
+    PropertyHolder().test2
+    PropertyHolder().test2 = ""
+
+    PropertyHolder().test3
+    PropertyHolder().test3 = ""
+
+    PropertyHolder().test4
+    PropertyHolder().test4 = ""
+
+    val a = PropertyHolder().x
+    val b = PropertyHolder().name
+    PropertyHolder().name = "value"
+
+    val d = PropertyHolder().valDelegate
+    PropertyHolder().varDelegate = 1
+}
+
+fun literals() {
+    PropertyHolder::test1
+    PropertyHolder::name
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/propertyUseSiteTargetedAnnotations.fir.kt b/compiler/testData/diagnostics/tests/deprecated/propertyUseSiteTargetedAnnotations.fir.kt
new file mode 100644
index 00000000000..1005ca88034
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/propertyUseSiteTargetedAnnotations.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+class PropertyHolder {
+    @Deprecated("")
+    val a1 = 1
+
+    @property:Deprecated("")
+    var a2 = ""
+
+    @get:Deprecated("")
+    public val withGetter: String = ""
+
+    @set:Deprecated("")
+    public var withSetter: String = ""
+}
+
+fun fn() {
+    val holder = PropertyHolder()
+
+    holder.a1
+    holder.a2
+    holder.withGetter
+    holder.withSetter = "A"
+}
+
+fun literals() {
+    PropertyHolder::a1
+    PropertyHolder::a2
+    PropertyHolder::withGetter
+    PropertyHolder::withSetter
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/propertyWithInvoke.fir.kt b/compiler/testData/diagnostics/tests/deprecated/propertyWithInvoke.fir.kt
new file mode 100644
index 00000000000..c5f23583e4b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/propertyWithInvoke.fir.kt
@@ -0,0 +1,6 @@
+@Deprecated("No")
+val f: () -> Unit = {}
+
+fun test() {
+    f()
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/thisUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/thisUsage.fir.kt
new file mode 100644
index 00000000000..cc5148216ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/thisUsage.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+@Deprecated("Use A instead") open class MyClass {
+    fun foo() {
+        val test = this
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/deprecated/typeUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/typeUsage.fir.kt
new file mode 100644
index 00000000000..992e7825664
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/typeUsage.fir.kt
@@ -0,0 +1,42 @@
+@Deprecated("Class")
+open class Obsolete {
+    fun use() {}
+}
+
+@Deprecated("Class")
+open class Obsolete2 @Deprecated("Constructor") constructor() {
+    fun use() {}
+}
+
+interface Generic<T>
+
+open class Derived() : Obsolete()
+
+class Derived2() : Derived()
+
+class TypeParam : Generic<Obsolete>
+
+object Object : Obsolete()
+
+class Properties {
+    val x : Obsolete = Obsolete()
+    var y : Obsolete = Obsolete()
+
+    var n : Obsolete
+        get() = Obsolete()
+        set(value) {}
+}
+
+fun param(param: Obsolete) { param.use() }
+
+fun funcParamReceiver(param: Obsolete.()->Unit) { Obsolete().<!UNRESOLVED_REFERENCE!>param<!>() }
+fun funcParamParam(param: (Obsolete)->Unit) { param(Obsolete()) }
+fun funcParamRetVal(param: ()->Obsolete) { param() }
+
+fun <T: Obsolete> constraint() {}
+
+fun Obsolete.receiver() {}
+
+fun retVal(): Obsolete = Obsolete()
+
+fun nullableRetVal(): Obsolete? = null
diff --git a/compiler/testData/diagnostics/tests/deprecated/typealiasCompanionObject.fir.kt b/compiler/testData/diagnostics/tests/deprecated/typealiasCompanionObject.fir.kt
new file mode 100644
index 00000000000..de07e15f95b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/typealiasCompanionObject.fir.kt
@@ -0,0 +1,12 @@
+class Relevant {
+    companion object {
+        val value = ""
+    }
+}
+
+@Deprecated("Use Relevant")
+typealias Obsolete = Relevant
+
+fun test1() = Obsolete
+fun test2() = Obsolete.<!UNRESOLVED_REFERENCE!>value<!>
+fun test3() = Obsolete.toString()
diff --git a/compiler/testData/diagnostics/tests/deprecated/typealiasConstructor.fir.kt b/compiler/testData/diagnostics/tests/deprecated/typealiasConstructor.fir.kt
new file mode 100644
index 00000000000..558f6dc9a95
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/typealiasConstructor.fir.kt
@@ -0,0 +1,17 @@
+@Deprecated("Deprecated class")
+open class DeprecatedClass
+
+open class WithDeprecatedCtor(val x: Int) {
+    @Deprecated("Deprecated constructor")
+    constructor() : this(0)
+}
+
+typealias DeprecatedClassAlias = DeprecatedClass
+typealias WithDeprecatedCtorAlias = WithDeprecatedCtor
+typealias ArrayListOfDeprecatedClass = ArrayList<DeprecatedClass>
+
+class Test1 : DeprecatedClassAlias()
+
+class Test2 : WithDeprecatedCtorAlias()
+
+val test3 = ArrayListOfDeprecatedClass()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/typealiasForDeprecatedClass.fir.kt b/compiler/testData/diagnostics/tests/deprecated/typealiasForDeprecatedClass.fir.kt
new file mode 100644
index 00000000000..da64d0df0df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/typealiasForDeprecatedClass.fir.kt
@@ -0,0 +1,21 @@
+@Deprecated("")
+class Foo
+
+@Deprecated("", level = DeprecationLevel.ERROR)
+class Err
+
+typealias Test1 = Foo
+typealias Test2 = List<Foo>
+typealias Test3 = List<Test2>
+
+typealias TestErr1 = Err
+typealias TestErr2 = List<Err>
+typealias TestErr3 = List<TestErr2>
+
+fun use1(b: Test1) = b
+fun use2(b: Test2) = b
+fun use3(b: Test3) = b
+
+fun useErr1(b: TestErr1) = b
+fun useErr2(b: TestErr2) = b
+fun useErr3(b: TestErr3) = b
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/typealiasUsage.fir.kt b/compiler/testData/diagnostics/tests/deprecated/typealiasUsage.fir.kt
new file mode 100644
index 00000000000..6ac0193e35c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/typealiasUsage.fir.kt
@@ -0,0 +1,24 @@
+open class Base {
+    companion object
+}
+interface IFoo
+open class CG<T>
+interface IG<T>
+
+@Deprecated("Obsolete")
+typealias Obsolete = Base
+
+@Deprecated("Obsolete")
+typealias IObsolete = IFoo
+
+fun test1(x: Obsolete) = x
+fun test1a(x: List<Obsolete>) = x
+
+val test2 = Obsolete()
+
+val test3 = Obsolete
+
+class Test4: Obsolete()
+class Test4a: IObsolete
+class Test4b: IG<Obsolete>
+class Test4c: CG<Obsolete>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/deprecated/unusedImport.fir.kt b/compiler/testData/diagnostics/tests/deprecated/unusedImport.fir.kt
new file mode 100644
index 00000000000..67783b81d14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/unusedImport.fir.kt
@@ -0,0 +1,10 @@
+// FILE: A.kt
+
+package test
+
+@Deprecated("A")
+interface A
+
+// FILE: B.kt
+
+import test.A
diff --git a/compiler/testData/diagnostics/tests/deprecated/warningOnConstructorErrorOnClass.fir.kt b/compiler/testData/diagnostics/tests/deprecated/warningOnConstructorErrorOnClass.fir.kt
new file mode 100644
index 00000000000..fa8936a712d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/deprecated/warningOnConstructorErrorOnClass.fir.kt
@@ -0,0 +1,8 @@
+// KT-15245 Report deprecation on associated declarations if level is greater than the deprecation on the declaration itself
+
+@Deprecated("error", level = DeprecationLevel.ERROR)
+class Foo @Deprecated("warning", level = DeprecationLevel.WARNING) constructor()
+
+fun test1() = Foo()
+
+fun test2(): Foo = Foo()
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/accidentalOverrideFromGrandparent.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/accidentalOverrideFromGrandparent.fir.kt
new file mode 100644
index 00000000000..6ed1c87836d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/accidentalOverrideFromGrandparent.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+interface Foo<X> {
+    fun foo(x: X)
+}
+
+open class FooImpl : Foo<String> {
+    override fun foo(x: String) {
+    }
+}
+
+open class FooImpl2 : FooImpl() {
+    fun foo(x: Any) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByProperty.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByProperty.fir.kt
new file mode 100644
index 00000000000..1b31212ede8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByProperty.fir.kt
@@ -0,0 +1,8 @@
+open class B {
+    fun getX() = 1
+}
+
+class C : B() {
+    val x: Int
+        get() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByPropertyInConstructor.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByPropertyInConstructor.fir.kt
new file mode 100644
index 00000000000..06b6b65787a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByPropertyInConstructor.fir.kt
@@ -0,0 +1,5 @@
+open class B {
+    fun getX() = 1
+}
+
+class C(val x: Int) : B()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByPropertyNoGetter.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByPropertyNoGetter.fir.kt
new file mode 100644
index 00000000000..ad7d1ce6e01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classFunctionOverriddenByPropertyNoGetter.fir.kt
@@ -0,0 +1,7 @@
+open class B {
+    fun getX() = 1
+}
+
+class C : B() {
+    val x: Int = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classPropertyOverriddenByFunction.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classPropertyOverriddenByFunction.fir.kt
new file mode 100644
index 00000000000..672f4f7f5d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/classPropertyOverriddenByFunction.fir.kt
@@ -0,0 +1,8 @@
+open class B {
+    val x: Int
+        get() = 1
+}
+
+class C : B() {
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/defaultFunction.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/defaultFunction.fir.kt
new file mode 100644
index 00000000000..2f56836984a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/defaultFunction.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class Base {
+    open fun `foo$default`(d: Derived, i: Int, mask: Int, mh: Any) {}
+}
+
+class Derived : Base() {
+    fun foo(i: Int = 0) {}
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/delegatedFunctionOverriddenByProperty.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/delegatedFunctionOverriddenByProperty.fir.kt
new file mode 100644
index 00000000000..e4319933d85
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/delegatedFunctionOverriddenByProperty.fir.kt
@@ -0,0 +1,10 @@
+interface B {
+    fun getX() = 1
+}
+
+interface D {
+    val x: Int
+}
+
+class C(d: D) : D by d, B {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/genericClassFunction.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/genericClassFunction.fir.kt
new file mode 100644
index 00000000000..ca3514cd1e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/genericClassFunction.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class B {
+    fun foo(l: List<String>) {}
+}
+
+class C : B() {
+    fun foo(l: List<Int>) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/overridesNothing.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/overridesNothing.fir.kt
new file mode 100644
index 00000000000..664ad15e830
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/overridesNothing.fir.kt
@@ -0,0 +1,7 @@
+interface B {
+    fun getX() = 1
+}
+
+class C : B {
+    override val x = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/privateClassFunctionOverriddenByProperty.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/privateClassFunctionOverriddenByProperty.fir.kt
new file mode 100644
index 00000000000..f6c76cb59ce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/privateClassFunctionOverriddenByProperty.fir.kt
@@ -0,0 +1,8 @@
+open class B {
+    private fun getX() = 1
+}
+
+class C : B() {
+    val x: Int
+        get() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/require.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/require.fir.kt
new file mode 100644
index 00000000000..ade55e7396d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/require.fir.kt
@@ -0,0 +1,7 @@
+open class C {
+    val x = 1
+}
+
+interface Tr : C {
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitFunctionOverriddenByProperty.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitFunctionOverriddenByProperty.fir.kt
new file mode 100644
index 00000000000..edcd5abff9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitFunctionOverriddenByProperty.fir.kt
@@ -0,0 +1,8 @@
+interface T {
+    fun getX() = 1
+}
+
+class C : T {
+    val x: Int
+        get() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitFunctionOverriddenByPropertyNoImpl.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitFunctionOverriddenByPropertyNoImpl.fir.kt
new file mode 100644
index 00000000000..d78dd659bb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitFunctionOverriddenByPropertyNoImpl.fir.kt
@@ -0,0 +1,8 @@
+interface T {
+    fun getX(): Int
+}
+
+abstract class C : T {
+    val x: Int
+        get() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitPropertyOverriddenByFunction.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitPropertyOverriddenByFunction.fir.kt
new file mode 100644
index 00000000000..ff9451649a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitPropertyOverriddenByFunction.fir.kt
@@ -0,0 +1,8 @@
+interface T {
+    val x: Int
+        get() = 1
+}
+
+class C : T {
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitPropertyOverriddenByFunctionNoImpl.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitPropertyOverriddenByFunctionNoImpl.fir.kt
new file mode 100644
index 00000000000..002e8217385
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/accidentalOverrides/traitPropertyOverriddenByFunctionNoImpl.fir.kt
@@ -0,0 +1,7 @@
+interface T {
+    val x: Int
+}
+
+abstract class C : T {
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/class.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/class.fir.kt
new file mode 100644
index 00000000000..b6a7692433a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/class.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class B<T> {
+    open fun foo(t: T) {}
+}
+
+class C : B<String>() {
+    override fun foo(t: String) {}
+
+    fun foo(o: Any) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/fakeOverrideTrait.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/fakeOverrideTrait.fir.kt
new file mode 100644
index 00000000000..817b75ed780
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/fakeOverrideTrait.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface B<T> {
+    fun foo(t: T) {}
+}
+
+class C : B<String> {
+    fun foo(o: Any) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/trait.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/trait.fir.kt
new file mode 100644
index 00000000000..c931a0413e7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/bridges/trait.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface B<T> {
+    fun foo(t: T) {}
+}
+
+class C : B<String> {
+    override fun foo(t: String) {}
+
+    fun foo(o: Any) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/caseInProperties.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/caseInProperties.fir.kt
new file mode 100644
index 00000000000..8bf6f093521
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/caseInProperties.fir.kt
@@ -0,0 +1,2 @@
+val aa = 1
+val Aa = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/clashFromInterfaceAndSuperClass.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/clashFromInterfaceAndSuperClass.fir.kt
new file mode 100644
index 00000000000..e5730dcdd4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/clashFromInterfaceAndSuperClass.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+public open class A<T> {
+    fun foo(x: T) = "O"
+    fun foo(x: A<T>) = "K"
+}
+
+interface C<E> {
+    fun foo(x: E): String
+    fun foo(x: A<E>): String
+}
+
+interface D {
+    fun foo(x: A<String>): String
+}
+
+class B1 : A<A<String>>(), D
+
+interface B2 : C<A<String>>, D
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/collections.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/collections.fir.kt
new file mode 100644
index 00000000000..ad06df1d2bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/collections.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(s: List<String>) {}
+fun foo(s: MutableList<String>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegateToTwoTraits.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegateToTwoTraits.fir.kt
new file mode 100644
index 00000000000..cd117843562
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegateToTwoTraits.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo<T> {
+    fun foo(l: List<T>)
+}
+
+interface Bar<T> {
+    fun foo(l: List<T>)
+}
+
+class Baz(f: Foo<String>, b: Bar<Int>): Foo<String> by f, Bar<Int> by b {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegationAndOwnMethod.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegationAndOwnMethod.fir.kt
new file mode 100644
index 00000000000..febee25b6b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegationAndOwnMethod.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo<T> {
+    fun foo(l: List<T>)
+}
+
+class Bar(f: Foo<String>): Foo<String> by f {
+    fun foo(l: List<Int>) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegationToTraitImplAndOwnMethod.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegationToTraitImplAndOwnMethod.fir.kt
new file mode 100644
index 00000000000..74fe8e60254
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/delegationToTraitImplAndOwnMethod.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo<T> {
+    fun foo(l: List<T>) {
+
+    }
+}
+
+class Bar(f: Foo<String>): Foo<String> by f {
+    fun foo(l: List<Int>) {}
+}
+
+class BarOther(f: Foo<String>): Foo<String> by f {
+    override fun foo(l: List<String>) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/extensionProperties.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/extensionProperties.fir.kt
new file mode 100644
index 00000000000..a609f1a780a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/extensionProperties.fir.kt
@@ -0,0 +1,7 @@
+class G<T>
+
+val <T> G<T>.foo: Int
+    get() = 1
+
+val G<String>.foo: Int
+    get() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/genericType.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/genericType.fir.kt
new file mode 100644
index 00000000000..d1ba83124eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/genericType.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class G<T>
+
+fun foo(x: G<String>): G<Int> {null!!}
+fun foo(x: G<Int>): G<String> {null!!}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/inheritFromTwoTraits.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/inheritFromTwoTraits.fir.kt
new file mode 100644
index 00000000000..65473004235
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/inheritFromTwoTraits.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo<T> {
+    fun foo(l: List<T>) {}
+}
+
+interface Bar<T> {
+    fun foo(l: List<T>) {}
+}
+
+class Baz(): Foo<String>, Bar<Int> {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/kotlinAndJavaCollections.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/kotlinAndJavaCollections.fir.kt
new file mode 100644
index 00000000000..4d292586540
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/kotlinAndJavaCollections.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PLATFORM_CLASS_MAPPED_TO_KOTLIN
+
+fun foo(s: List<String>) {}
+fun foo(s: java.util.List<String>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/nullableType.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/nullableType.fir.kt
new file mode 100644
index 00000000000..be18b4cef95
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/nullableType.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(x: String) {}
+fun foo(x: String?) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/superTraitAndDelegationToTraitImpl.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/superTraitAndDelegationToTraitImpl.fir.kt
new file mode 100644
index 00000000000..7fecce1889a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/superTraitAndDelegationToTraitImpl.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A<T> {
+    fun foo(l: List<T>)
+}
+
+interface B {
+    fun foo(l: List<Int>) {}
+}
+
+class C(f: A<String>): A<String> by f, B
+
+class D(f: A<Int>): A<Int> by f, B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/twoTraitsAndOwnFunction.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/twoTraitsAndOwnFunction.fir.kt
new file mode 100644
index 00000000000..77563b2f25d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/twoTraitsAndOwnFunction.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo<T> {
+    fun foo(l: List<T>) {}
+}
+
+interface Bar<T> {
+    fun foo(l: List<T>) {}
+}
+
+class Baz(): Foo<String>, Bar<Int> {
+    fun foo(l: List<Long>) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeMappedToJava.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeMappedToJava.fir.kt
new file mode 100644
index 00000000000..1db144a121c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeMappedToJava.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PLATFORM_CLASS_MAPPED_TO_KOTLIN
+
+fun foo(s: java.lang.String) {}
+fun foo(s: String) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameter.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameter.fir.kt
new file mode 100644
index 00000000000..16fc6848222
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameter.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> foo(x: T): T {null!!}
+fun foo(x: Any): Any {null!!}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithBound.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithBound.fir.kt
new file mode 100644
index 00000000000..d8a12296201
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithBound.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo
+
+fun <T: Foo> foo(x: T): T {null!!}
+fun foo(x: Foo): Foo {null!!}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithTwoBounds.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithTwoBounds.fir.kt
new file mode 100644
index 00000000000..92c1825fd8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithTwoBounds.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo
+interface Bar
+
+fun <T> foo(x: T): T where T: Foo, T: Bar {null!!}
+fun foo(x: Foo): Foo {null!!}
+fun foo(x: Bar): Bar {null!!}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithTwoBoundsInWhere.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithTwoBoundsInWhere.fir.kt
new file mode 100644
index 00000000000..92c1825fd8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/erasure/typeParameterWithTwoBoundsInWhere.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo
+interface Bar
+
+fun <T> foo(x: T): T where T: Foo, T: Bar {null!!}
+fun foo(x: Foo): Foo {null!!}
+fun foo(x: Bar): Bar {null!!}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/finalMembersFromBuiltIns/enumMembers.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/finalMembersFromBuiltIns/enumMembers.fir.kt
new file mode 100644
index 00000000000..8bc20f758b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/finalMembersFromBuiltIns/enumMembers.fir.kt
@@ -0,0 +1,6 @@
+enum class E {
+    ENTRY;
+
+    fun getDeclaringClass() {}
+    fun finalize() {}
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/finalMembersFromBuiltIns/waitNotifyGetClass.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/finalMembersFromBuiltIns/waitNotifyGetClass.fir.kt
new file mode 100644
index 00000000000..434e35c0703
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/finalMembersFromBuiltIns/waitNotifyGetClass.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// KT-7174 Report error on members with the same signature as non-overridable methods from mapped Java types (like Object.wait/notify)
+
+class A {
+    fun notify() {}
+    fun notifyAll() {}
+    fun wait() {}
+    fun wait(l: Long) {}
+    fun wait(l: Long, i: Int) {}
+    fun getClass(): Class<Any> = null!!
+}
+
+fun notify() {}
+fun notifyAll() {}
+fun wait() {}
+fun wait(l: Long) {}
+fun wait(l: Long, i: Int) {}
+fun getClass(): Class<Any> = null!!
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/class.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/class.fir.kt
new file mode 100644
index 00000000000..9cd7beedbcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/class.fir.kt
@@ -0,0 +1,4 @@
+class C {
+    val x = 1
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classObject.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classObject.fir.kt
new file mode 100644
index 00000000000..5cbee7e1f34
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classObject.fir.kt
@@ -0,0 +1,6 @@
+class C {
+    companion object {
+        val x = 1
+        fun getX() = 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classPropertyInConstructor.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classPropertyInConstructor.fir.kt
new file mode 100644
index 00000000000..c3ae39cecab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/classPropertyInConstructor.fir.kt
@@ -0,0 +1,3 @@
+class C(val x: Int) {
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/extensionFunctionAndNormalFunction.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/extensionFunctionAndNormalFunction.fir.kt
new file mode 100644
index 00000000000..a58a20fe15d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/extensionFunctionAndNormalFunction.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    fun foo(x: Any) {}
+    fun Any.foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/extensionPropertyAndFunction.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/extensionPropertyAndFunction.fir.kt
new file mode 100644
index 00000000000..e615b559530
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/extensionPropertyAndFunction.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    fun getX(t: Any) = 1
+    val Any.x: Int
+        get() = 1
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/functionAndSetter.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/functionAndSetter.fir.kt
new file mode 100644
index 00000000000..b0f82f15b14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/functionAndSetter.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    fun setX(x: Int) {}
+
+    var x: Int = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/functionAndVar.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/functionAndVar.fir.kt
new file mode 100644
index 00000000000..14c42f4056e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/functionAndVar.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    fun setX(x: Int) {}
+
+    var x: Int = 1
+        set(v) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/localClass.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/localClass.fir.kt
new file mode 100644
index 00000000000..eea8020a118
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/localClass.fir.kt
@@ -0,0 +1,6 @@
+fun foo() {
+    class C {
+        val x = 1
+        fun getX() = 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/localClassInClass.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/localClassInClass.fir.kt
new file mode 100644
index 00000000000..c341cf3acfc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/localClassInClass.fir.kt
@@ -0,0 +1,8 @@
+class Outer {
+    fun foo() {
+        class C {
+            val x = 1
+            fun getX() = 1
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/nestedClass.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/nestedClass.fir.kt
new file mode 100644
index 00000000000..1bbfa664537
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/nestedClass.fir.kt
@@ -0,0 +1,6 @@
+class B {
+    class C {
+        val x = 1
+        fun getX() = 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/object.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/object.fir.kt
new file mode 100644
index 00000000000..fbd894a67f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/object.fir.kt
@@ -0,0 +1,4 @@
+object C {
+    val x = 1
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/objectExpression.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/objectExpression.fir.kt
new file mode 100644
index 00000000000..01d6b6959c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/objectExpression.fir.kt
@@ -0,0 +1,5 @@
+fun foo() =
+    object {
+        val x = 1
+        fun getX() = 1
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/objectExpressionInConstructor.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/objectExpressionInConstructor.fir.kt
new file mode 100644
index 00000000000..262025fbeff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/objectExpressionInConstructor.fir.kt
@@ -0,0 +1,6 @@
+class Outer {
+    val x = object {
+        val x = 1
+        fun getX() = 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/privateClassPropertyNoClash.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/privateClassPropertyNoClash.fir.kt
new file mode 100644
index 00000000000..9fcf9ce0da1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/privateClassPropertyNoClash.fir.kt
@@ -0,0 +1,13 @@
+// FILE: A.java
+
+public class A {
+    public String getFoo() {
+        return "Foo";
+    }
+}
+
+// FILE: B.kt
+
+class B(private val foo: String) : A() {
+    override fun getFoo(): String = foo
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevel.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevel.fir.kt
new file mode 100644
index 00000000000..5d0ee3abfc2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevel.fir.kt
@@ -0,0 +1,2 @@
+val x = 1
+fun getX() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevelDifferentFiles.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevelDifferentFiles.fir.kt
new file mode 100644
index 00000000000..568f17314a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevelDifferentFiles.fir.kt
@@ -0,0 +1,5 @@
+// FILE: a.kt
+val x = 1
+
+// FILE: b.kt
+fun getX() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevelGetter.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevelGetter.fir.kt
new file mode 100644
index 00000000000..29a9e2a007a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/topLevelGetter.fir.kt
@@ -0,0 +1,3 @@
+val x: Int
+    get() = 1
+fun getX() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/trait.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/trait.fir.kt
new file mode 100644
index 00000000000..57cd160985c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/trait.fir.kt
@@ -0,0 +1,5 @@
+interface T {
+    val x: Int
+        get() = 1
+    fun getX() = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/withErrorTypes.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/withErrorTypes.fir.kt
new file mode 100644
index 00000000000..142dfe5fdb2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/functionAndProperty/withErrorTypes.fir.kt
@@ -0,0 +1,4 @@
+interface T {
+    val x: ErrorType
+    fun getX(): ErrorType1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/missingNames.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/missingNames.fir.kt
new file mode 100644
index 00000000000..9bf897065b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/missingNames.fir.kt
@@ -0,0 +1,68 @@
+// !DIAGNOSTICS: -DUPLICATE_CLASS_NAMES
+fun () {
+
+}
+
+fun Outer.() {
+
+}
+
+val<!SYNTAX!><!> : Int = 1
+
+class<!SYNTAX!><!> {
+
+}
+
+object<!SYNTAX!><!> {
+
+}
+
+interface<!SYNTAX!><!> {
+
+}
+
+enum class<!SYNTAX!><!> {
+
+}
+
+annotation class<!SYNTAX!><!> {
+
+}
+
+class Outer {
+    fun () {
+
+    }
+
+    val<!SYNTAX!><!> : Int = 1
+
+    class<!SYNTAX!><!> {
+
+    }
+
+    object<!SYNTAX!><!> {
+
+    }
+
+    interface<!SYNTAX!><!> {
+
+    }
+
+    enum class<!SYNTAX!><!> {
+
+    }
+
+    annotation class<!SYNTAX!><!> {
+
+    }
+}
+
+fun outerFun() {
+    fun () {
+
+    }
+    fun () {
+
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObject.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObject.fir.kt
new file mode 100644
index 00000000000..653071684ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObject.fir.kt
@@ -0,0 +1,5 @@
+class C {
+    companion object {}
+
+    val Companion = C
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObjectCopiedField.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObjectCopiedField.fir.kt
new file mode 100644
index 00000000000..88105c1b936
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObjectCopiedField.fir.kt
@@ -0,0 +1,8 @@
+class C {
+    companion object {
+        val X = 1
+        val `X$1` = 1
+    }
+
+    val X = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObjectCopiedFieldObject.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObjectCopiedFieldObject.fir.kt
new file mode 100644
index 00000000000..4831e5ca1f0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/classObjectCopiedFieldObject.fir.kt
@@ -0,0 +1,13 @@
+class B {
+    companion object A {
+    }
+
+    val A = this
+}
+
+class C {
+    companion object A {
+        val A = this
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/dataClassCopy.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/dataClassCopy.fir.kt
new file mode 100644
index 00000000000..d92de0478f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/dataClassCopy.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+data class C(val c: Int) {
+    fun `copy$default`(c: C, x: Int, m: Int, mh: Any) = C(this.c)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/defaults.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/defaults.fir.kt
new file mode 100644
index 00000000000..2b1ff02393e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/defaults.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    fun `a$default`(c: C, x: Int, m: Int, mh: Any) {}
+    fun a(x: Int = 1) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/delegationBy.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/delegationBy.fir.kt
new file mode 100644
index 00000000000..abfad6e56b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/delegationBy.fir.kt
@@ -0,0 +1,5 @@
+interface Foo
+
+class Bar(f: Foo) : Foo by f {
+    val `$$delegate_0`: Foo? = null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/enum.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/enum.fir.kt
new file mode 100644
index 00000000000..e7673b24547
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/enum.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+enum class E {
+    A;
+
+    fun values(): Array<E> = null!!
+    fun valueOf(s: String): E = null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/innerClassField.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/innerClassField.fir.kt
new file mode 100644
index 00000000000..e12fd85dd65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/innerClassField.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    inner class D {
+        val `this$0`: C? = null
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/instance.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/instance.fir.kt
new file mode 100644
index 00000000000..89a99a64881
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/instance.fir.kt
@@ -0,0 +1,3 @@
+object O {
+    val INSTANCE: O = null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/propertyMetadataCache.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/propertyMetadataCache.fir.kt
new file mode 100644
index 00000000000..55e41e660c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/specialNames/propertyMetadataCache.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+operator fun Any.getValue(x: Any?, y: Any): Any = null!!
+
+class C {
+    val x by 1
+    val `$$delegatedProperties`: Array<KProperty<*>> = null!!
+}
+
+val x by 1
+val `$$delegatedProperties`: Array<KProperty<*>> = null!!
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/jkjk.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/jkjk.fir.kt
new file mode 100644
index 00000000000..76dccc40ce7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/jkjk.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A {
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: B.kt
+
+open class B : A() {
+}
+
+// FILE: C.java
+
+public class C extends B {
+    public static void bar(int i) {}
+}
+
+// FILE: K.kt
+
+open class K : C() {
+    fun foo() {}
+    fun foo(a: Any) {}
+    fun bar(i: Int) {}
+    fun bar(i: String) {}
+    fun baz(i: Int) {}
+
+    companion object {
+        fun foo() {}
+        fun bar(i: Int) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassExtendsJavaClass.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassExtendsJavaClass.fir.kt
new file mode 100644
index 00000000000..2935e2a02e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassExtendsJavaClass.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A {
+    public static int a = 1;
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: K.kt
+
+open class K : A() {
+    val a = 1
+    fun foo() {}
+    fun foo(i: Int) {}
+    fun baz(i: Int) {}
+
+    companion object {
+        fun foo() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassExtendsJavaClassExtendsJavaClass.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassExtendsJavaClassExtendsJavaClass.fir.kt
new file mode 100644
index 00000000000..cdeb98655d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassExtendsJavaClassExtendsJavaClass.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A {
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: B.java
+
+public class B extends A {
+    public static void bar(int i) {}
+}
+
+// FILE: K.kt
+
+open class K : B() {
+    fun foo() {}
+    fun foo(a: Any) {}
+    fun bar(i: Int) {}
+    fun bar(i: String) {}
+    fun baz(i: Int) {}
+
+    companion object {
+        fun foo() {}
+        fun bar(i: Int) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassImplementsJavaInterface.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassImplementsJavaInterface.fir.kt
new file mode 100644
index 00000000000..9561d68a6c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassImplementsJavaInterface.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public interface A {
+    public String a = "";
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: K.kt
+
+open class K : A {
+    val a = ""
+    fun foo() {}
+    fun foo(i: Int) {}
+    fun baz(i: Int) {}
+
+    companion object {
+        fun foo() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassImplementsJavaInterfaceExtendsJavaInteface.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassImplementsJavaInterfaceExtendsJavaInteface.fir.kt
new file mode 100644
index 00000000000..21ab1027a35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinClassImplementsJavaInterfaceExtendsJavaInteface.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public interface A {
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: B.java
+
+public interface B extends A {
+    public static void bar(int i) {}
+}
+
+// FILE: K.kt
+
+open class K : B {
+    fun foo() {}
+    fun foo(a: Any) {}
+    fun bar(i: Int) {}
+    fun bar(i: String) {}
+    fun baz(i: Int) {}
+
+    companion object {
+        fun foo() {}
+        fun bar(i: Int) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinMembersVsJavaNonVisibleStatics.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinMembersVsJavaNonVisibleStatics.fir.kt
new file mode 100644
index 00000000000..5cde834931a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/statics/kotlinMembersVsJavaNonVisibleStatics.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: foo/A.java
+
+package foo;
+
+public class A {
+    private static void foo(int s) {}
+    static void bar(double s) {}
+}
+
+// FILE: K.kt
+import foo.A
+
+open class K : A() {
+    fun foo(i: Int) {}
+    fun bar(d: Double) {}
+    fun baz(i: Int) {}
+
+    companion object {
+        fun foo(i: Int) {}
+        fun bar(d: Double) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/synthesized/enumValuesValueOf.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/synthesized/enumValuesValueOf.fir.kt
new file mode 100644
index 00000000000..56528c8094c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/synthesized/enumValuesValueOf.fir.kt
@@ -0,0 +1,12 @@
+enum class A {
+    A1,
+    A2;
+
+    fun valueOf(s: String): A = <!AMBIGUITY!>valueOf<!>(s)
+
+    fun valueOf() = "OK"
+
+    fun values(): Array<A> = null!!
+
+    fun values(x: String) = x
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/oneTrait.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/oneTrait.fir.kt
new file mode 100644
index 00000000000..eee1418b21a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/oneTrait.fir.kt
@@ -0,0 +1,7 @@
+interface T {
+    fun getX() = 1
+}
+
+class C : T {
+    val x = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/traitFunctionOverriddenByPropertyInTrait.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/traitFunctionOverriddenByPropertyInTrait.fir.kt
new file mode 100644
index 00000000000..20e46f71270
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/traitFunctionOverriddenByPropertyInTrait.fir.kt
@@ -0,0 +1,8 @@
+interface T {
+    fun getX() = 1
+}
+
+interface C : T {
+    val x: Int
+        get() = 1
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/traitPropertyOverriddenByFunctionInTrait.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/traitPropertyOverriddenByFunctionInTrait.fir.kt
new file mode 100644
index 00000000000..9f4368ce1ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/traitPropertyOverriddenByFunctionInTrait.fir.kt
@@ -0,0 +1,8 @@
+interface T {
+    val x: Int
+        get() = 1
+}
+
+interface C : T {
+    fun getX() = 1
+}
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/twoTraits.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/twoTraits.fir.kt
new file mode 100644
index 00000000000..88080b65dc3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/twoTraits.fir.kt
@@ -0,0 +1,11 @@
+interface T1 {
+    fun getX() = 1
+}
+
+interface T2 {
+    val x: Int
+        get() = 1
+}
+
+class C : T1, T2 {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/duplicateJvmSignature/vararg.fir.kt b/compiler/testData/diagnostics/tests/duplicateJvmSignature/vararg.fir.kt
new file mode 100644
index 00000000000..481498c275a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/duplicateJvmSignature/vararg.fir.kt
@@ -0,0 +1,8 @@
+fun foo(vararg x: Int) {}
+fun foo(x: IntArray) {}
+
+fun foo(vararg x: Int?) {}
+fun foo(x: Array<Int>) {}
+
+fun foo(vararg nn: Number) {}
+fun foo(nn: Array<out Number>) {}
diff --git a/compiler/testData/diagnostics/tests/dynamicTypes/delegationBy.fir.kt b/compiler/testData/diagnostics/tests/dynamicTypes/delegationBy.fir.kt
new file mode 100644
index 00000000000..b21ee696104
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dynamicTypes/delegationBy.fir.kt
@@ -0,0 +1,5 @@
+interface Tr {
+    fun foo()
+}
+
+class C(d: dynamic) : Tr by d
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/dynamicTypes/unsupported.fir.kt b/compiler/testData/diagnostics/tests/dynamicTypes/unsupported.fir.kt
new file mode 100644
index 00000000000..f80596ec429
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dynamicTypes/unsupported.fir.kt
@@ -0,0 +1,7 @@
+val foo: dynamic = 1
+
+fun foo() {
+    class C {
+        val foo: dynamic = 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/dynamicTypes/withInvisibleSynthesized.fir.kt b/compiler/testData/diagnostics/tests/dynamicTypes/withInvisibleSynthesized.fir.kt
new file mode 100644
index 00000000000..75cf307e6b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/dynamicTypes/withInvisibleSynthesized.fir.kt
@@ -0,0 +1,35 @@
+// !MARK_DYNAMIC_CALLS
+
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public static class C {
+        private void sam(Sam sam) {}
+    }
+
+
+    public interface Sam {
+        void sam();
+    }
+}
+
+// FILE: k.kt
+
+import p.*
+
+class K: J.C() {
+    fun dynamic.test() {
+        <!INAPPLICABLE_CANDIDATE!>sam<!>(null)
+        <!INAPPLICABLE_CANDIDATE!>sam<!>(
+            name = null,
+            name = null
+        )
+    }
+
+    fun test() {
+        <!INAPPLICABLE_CANDIDATE!>sam<!>(null)
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/AbstractEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/AbstractEnum.fir.kt
new file mode 100644
index 00000000000..a1961b8a648
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/AbstractEnum.fir.kt
@@ -0,0 +1,3 @@
+package abstract
+
+abstract enum class MyAbstractEnum() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/AbstractInEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/AbstractInEnum.fir.kt
new file mode 100644
index 00000000000..e5ba1ab9ddc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/AbstractInEnum.fir.kt
@@ -0,0 +1,47 @@
+package abstract
+
+
+enum class MyEnum() {
+    INSTANCE;
+    //properties
+    val a: Int
+    val a1: Int = 1
+    abstract val a2: Int
+    abstract val a3: Int = 1
+
+    var b: Int                private set
+    var b1: Int = 0;                         private set
+    abstract var b2: Int      private set
+    abstract var b3: Int = 0; private set
+
+    var c: Int                set(v: Int) { field = v }
+    var c1: Int = 0;                         set(v: Int) { field = v }
+    abstract var c2: Int                     set(v: Int) { field = v }
+    abstract var c3: Int = 0; set(v: Int) { field = v }
+
+    val e: Int                               get() = a
+    val e1: Int = 0;          get() = a
+    abstract val e2: Int                     get() = a
+    abstract val e3: Int = 0; get() = a
+
+    //methods
+    fun f()
+    fun g() {}
+    abstract fun h()
+    abstract fun j() {}
+
+    //property accessors
+    var i: Int                       abstract get  abstract set
+    var i1: Int = 0;  abstract get  abstract set
+
+    var j: Int                       get() = i;    abstract set
+    var j1: Int = 0;  get() = i;    abstract set
+
+    var k: Int        abstract set
+    var k1: Int = 0;                 abstract set
+
+    var l: Int                       abstract get  abstract set
+    var l1: Int = 0;   abstract get  abstract set
+
+    var n: Int                       abstract get abstract set(v: Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/AbstractOverrideInEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/AbstractOverrideInEnum.fir.kt
new file mode 100644
index 00000000000..bb97e9dce60
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/AbstractOverrideInEnum.fir.kt
@@ -0,0 +1,12 @@
+enum class E : T {
+    ENTRY {
+        override fun f() {
+        }
+    };
+
+    abstract override fun f()
+}
+
+interface T {
+    fun f()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/ConstructorCallFromOutside.fir.kt b/compiler/testData/diagnostics/tests/enum/ConstructorCallFromOutside.fir.kt
new file mode 100644
index 00000000000..0701f5ccc4f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/ConstructorCallFromOutside.fir.kt
@@ -0,0 +1,10 @@
+// KT-7753: attempt to call enum constructor explicitly
+enum class A(val c: Int) {
+    ONE(1),
+    TWO(2);    
+}
+
+fun createA(): A {
+    // Error should be here!
+    return <!INAPPLICABLE_CANDIDATE!>A<!>(10)
+}
diff --git a/compiler/testData/diagnostics/tests/enum/ExplicitConstructorCall.fir.kt b/compiler/testData/diagnostics/tests/enum/ExplicitConstructorCall.fir.kt
new file mode 100644
index 00000000000..9270790103b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/ExplicitConstructorCall.fir.kt
@@ -0,0 +1,10 @@
+// KT-7753: attempt to call enum constructor explicitly
+enum class A(val c: Int) {
+    ONE(1),
+    TWO(2);
+    
+    fun createA(): A {
+        // Error should be here!
+        return A(10)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/InsideEntryConstructorCall.fir.kt b/compiler/testData/diagnostics/tests/enum/InsideEntryConstructorCall.fir.kt
new file mode 100644
index 00000000000..5cb64b5db2d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/InsideEntryConstructorCall.fir.kt
@@ -0,0 +1,15 @@
+// KT-7753: attempt to call enum constructor explicitly
+enum class A(val c: Int) {
+    ONE(1) {
+        override fun selfOrFriend(): A {
+            return this
+        }
+    },
+    TWO(2) {
+        override fun selfOrFriend(): A {
+            return A(42)
+        }
+    };
+    
+    abstract fun selfOrFriend(): A
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/InsideSecondaryConstructorCall.fir.kt b/compiler/testData/diagnostics/tests/enum/InsideSecondaryConstructorCall.fir.kt
new file mode 100644
index 00000000000..c10af850cea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/InsideSecondaryConstructorCall.fir.kt
@@ -0,0 +1,13 @@
+// KT-7753: attempt to call enum constructor explicitly
+enum class A(val c: Int) {
+    ONE(1),
+    TWO(2),
+    THREE(3),
+    FORTY_TWO();
+
+    var last: A? = null
+
+    constructor(): this(42) {
+        last = A(13)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/NonPrivateConstructor.fir.kt b/compiler/testData/diagnostics/tests/enum/NonPrivateConstructor.fir.kt
new file mode 100644
index 00000000000..d13b99a1d75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/NonPrivateConstructor.fir.kt
@@ -0,0 +1,7 @@
+enum class E public constructor(val x: Int) {
+    FIRST();
+
+    internal constructor(): this(42)
+
+    constructor(y: Int, z: Int): this(y + z)
+}
diff --git a/compiler/testData/diagnostics/tests/enum/SecondaryConstructorCall.fir.kt b/compiler/testData/diagnostics/tests/enum/SecondaryConstructorCall.fir.kt
new file mode 100644
index 00000000000..303a241d6a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/SecondaryConstructorCall.fir.kt
@@ -0,0 +1,9 @@
+// KT-7753 false positive: enum constructor can be called from secondary constructor
+enum class A(val c: Int) {
+    ONE(1),
+    TWO(2),
+    THREE(3),
+    FORTY_TWO();
+
+    constructor(): this(42)   
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/classObjectInEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/classObjectInEnum.fir.kt
new file mode 100644
index 00000000000..2dfdccc2e2c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/classObjectInEnum.fir.kt
@@ -0,0 +1,9 @@
+enum class E {
+    ENTRY;
+
+    companion object {
+        fun entry() = ENTRY
+    }
+}
+
+fun bar() = E.entry()
diff --git a/compiler/testData/diagnostics/tests/enum/classObjectInEnumPrivate.fir.kt b/compiler/testData/diagnostics/tests/enum/classObjectInEnumPrivate.fir.kt
new file mode 100644
index 00000000000..e74ba426a8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/classObjectInEnumPrivate.fir.kt
@@ -0,0 +1,10 @@
+enum class E {
+    ENTRY;
+
+    private companion object
+}
+
+fun foo() = E.values()
+fun bar() = E.valueOf("ENTRY")
+fun baz() = E.ENTRY
+fun quux() = E
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/commonSupertype.fir.kt b/compiler/testData/diagnostics/tests/enum/commonSupertype.fir.kt
new file mode 100644
index 00000000000..31bda9beea4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/commonSupertype.fir.kt
@@ -0,0 +1,7 @@
+// KT-5943 StackOverflowError from commonSupertype of two enums
+// NI_EXPECTED_FILE
+
+enum class A { A }
+enum class B { B }
+
+val x = if (true) A.A else B.B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.fir.kt b/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.fir.kt
new file mode 100644
index 00000000000..b07eaeb661f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/compareTwoDifferentEnums.fir.kt
@@ -0,0 +1,16 @@
+// FILE: JavaEnumA.java
+
+public enum JavaEnumA {}
+
+// FILE: JavaEnumB.java
+
+public enum JavaEnumB {}
+
+// FILE: test.kt
+
+enum class KotlinEnumA
+enum class KotlinEnumB
+
+fun jj(a: JavaEnumA, b: JavaEnumB) = a == b
+fun jk(a: JavaEnumA, b: KotlinEnumB) = a == b
+fun kk(a: KotlinEnumA, b: KotlinEnumB) = a == b
diff --git a/compiler/testData/diagnostics/tests/enum/constructorWithDefaultParametersOnly.fir.kt b/compiler/testData/diagnostics/tests/enum/constructorWithDefaultParametersOnly.fir.kt
new file mode 100644
index 00000000000..3d010151b8d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/constructorWithDefaultParametersOnly.fir.kt
@@ -0,0 +1,21 @@
+enum class TestOk(val x: String = "OK") {
+    TEST1,
+    TEST2(),
+    TEST3("Hello")
+}
+
+enum class TestErrors(val x: String) {
+    TEST1,
+    TEST2<!INAPPLICABLE_CANDIDATE!><!>(),
+    TEST3("Hello")
+}
+
+enum class TestMultipleConstructors(val x: String = "", val y: Int = 0) {
+    TEST;
+    constructor(x: String = "") : this(x, 0)
+}
+
+enum class TestVarargs(val x: Int) {
+    TEST;
+    constructor(vararg xs: Any) : this(xs.size)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/dontCreatePackageTypeForEnumEntry_after.fir.kt b/compiler/testData/diagnostics/tests/enum/dontCreatePackageTypeForEnumEntry_after.fir.kt
new file mode 100644
index 00000000000..867145131f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/dontCreatePackageTypeForEnumEntry_after.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +NestedClassesInEnumEntryShouldBeInner
+
+enum class E {
+    FIRST,
+    SECOND {
+        class A
+    };
+}
+
+val foo: Any.() -> Unit = {}
+
+fun f1() = E.FIRST.<!UNRESOLVED_REFERENCE!>foo<!>()
+fun f2() = E.FIRST.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+fun f3() = E.SECOND.<!UNRESOLVED_REFERENCE!>foo<!>()
+fun f4() = E.SECOND.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+fun f5() = E.SECOND.A()
diff --git a/compiler/testData/diagnostics/tests/enum/dontCreatePackageTypeForEnumEntry_before.fir.kt b/compiler/testData/diagnostics/tests/enum/dontCreatePackageTypeForEnumEntry_before.fir.kt
new file mode 100644
index 00000000000..8e7216c011a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/dontCreatePackageTypeForEnumEntry_before.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: -NestedClassesInEnumEntryShouldBeInner
+
+enum class E {
+    FIRST,
+    SECOND {
+        class A
+    };
+}
+
+val foo: Any.() -> Unit = {}
+
+fun f1() = E.FIRST.<!UNRESOLVED_REFERENCE!>foo<!>()
+fun f2() = E.FIRST.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+fun f3() = E.SECOND.<!UNRESOLVED_REFERENCE!>foo<!>()
+fun f4() = E.SECOND.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+fun f5() = E.SECOND.A()
diff --git a/compiler/testData/diagnostics/tests/enum/emptyConstructor.fir.kt b/compiler/testData/diagnostics/tests/enum/emptyConstructor.fir.kt
new file mode 100644
index 00000000000..97493b36a35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/emptyConstructor.fir.kt
@@ -0,0 +1,4 @@
+enum class E {
+    A; // no constructor call needed
+    constructor()
+}
diff --git a/compiler/testData/diagnostics/tests/enum/entryShouldBeOfEnumType.fir.kt b/compiler/testData/diagnostics/tests/enum/entryShouldBeOfEnumType.fir.kt
new file mode 100644
index 00000000000..336cfe9493e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/entryShouldBeOfEnumType.fir.kt
@@ -0,0 +1,9 @@
+enum class E {
+    E1,
+    E2
+}
+
+fun foo() {
+    var e = E.E1
+    e = E.E2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumEntryCannotHaveClassObject.fir.kt b/compiler/testData/diagnostics/tests/enum/enumEntryCannotHaveClassObject.fir.kt
new file mode 100644
index 00000000000..308f3146a45
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumEntryCannotHaveClassObject.fir.kt
@@ -0,0 +1,11 @@
+enum class E {
+    FIRST,
+
+    SECOND {
+        companion object {
+            fun foo() = 42
+        }
+    };
+}
+
+fun f() = E.SECOND.<!UNRESOLVED_REFERENCE!>foo<!>()
diff --git a/compiler/testData/diagnostics/tests/enum/enumEntryInAbstractEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/enumEntryInAbstractEnum.fir.kt
new file mode 100644
index 00000000000..d3ba8db322a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumEntryInAbstractEnum.fir.kt
@@ -0,0 +1,13 @@
+enum class EnumClass {
+    E1 {
+        override fun foo() = 1
+        override val bar: String = "a"
+    },
+
+    E2 {
+
+    };
+
+    abstract fun foo(): Int
+    abstract val bar: String
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumImplementingTrait.fir.kt b/compiler/testData/diagnostics/tests/enum/enumImplementingTrait.fir.kt
new file mode 100644
index 00000000000..3faa491a53d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumImplementingTrait.fir.kt
@@ -0,0 +1,21 @@
+interface T1 {
+    fun foo()
+}
+
+enum class EnumImplementingTraitWithFun: T1 {
+    E1 {
+        override fun foo() {}
+    },
+    E2
+}
+
+interface T2 {
+    val bar: Int
+}
+
+enum class EnumImplementingTraitWithVal: T2 {
+    E1 {
+        override val bar = 1
+    },
+    E2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumInheritance.fir.kt b/compiler/testData/diagnostics/tests/enum/enumInheritance.fir.kt
new file mode 100644
index 00000000000..2da6449c35f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumInheritance.fir.kt
@@ -0,0 +1,11 @@
+// FILE: test.kt
+enum class MyEnum(): MyClass() {}
+enum class MyEnum2(): MyTrait {}
+enum class MyEnum3(): <!INAPPLICABLE_CANDIDATE!>MyEnumBase<!>() {}
+
+open class MyClass() {}
+
+enum class MyEnumBase() {}
+
+interface MyTrait {}
+
diff --git a/compiler/testData/diagnostics/tests/enum/enumIsAssignableToBuiltInEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/enumIsAssignableToBuiltInEnum.fir.kt
new file mode 100644
index 00000000000..8b9d867bd49
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumIsAssignableToBuiltInEnum.fir.kt
@@ -0,0 +1,14 @@
+import java.lang.annotation.RetentionPolicy
+
+enum class E {
+    ENTRY
+}
+
+// Test resolve from source
+val a: Enum<E> = E.ENTRY
+
+// Test Java resolve
+val b: Enum<RetentionPolicy> = RetentionPolicy.RUNTIME
+
+// Test deserialized resolve
+val c: Enum<AnnotationTarget> = AnnotationTarget.CLASS
diff --git a/compiler/testData/diagnostics/tests/enum/enumMissingName.fir.kt b/compiler/testData/diagnostics/tests/enum/enumMissingName.fir.kt
new file mode 100644
index 00000000000..3c643de9647
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumMissingName.fir.kt
@@ -0,0 +1,6 @@
+// Error: name should present
+enum class<!SYNTAX!><!>(val rgb : Int) {
+    RED(0xFF000),
+    GREEN(0x00FF00),
+    BLUE(0x0000FF)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumModifier.fir.kt b/compiler/testData/diagnostics/tests/enum/enumModifier.fir.kt
new file mode 100644
index 00000000000..9dfe7b9878c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumModifier.fir.kt
@@ -0,0 +1,15 @@
+enum class B {}
+
+class A {
+   enum companion object {}
+}
+
+enum object O {}
+
+enum interface T {}
+
+enum fun f() = 0
+
+enum val x = 0
+
+enum var y = 0
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumStarImport.fir.kt b/compiler/testData/diagnostics/tests/enum/enumStarImport.fir.kt
new file mode 100644
index 00000000000..59cd5488439
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumStarImport.fir.kt
@@ -0,0 +1,20 @@
+// FILE: enum.kt
+
+package enum
+
+enum class HappyEnum {
+    CASE1,
+    CASE2
+}
+
+// FILE: user.kt
+
+import enum.HappyEnum
+import enum.HappyEnum.*
+
+fun f(e: HappyEnum) {
+    when (e) {
+        CASE1 -> throw UnsupportedOperationException() // unresolved reference
+        CASE2 -> throw UnsupportedOperationException() // unresolved references
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumSubjectTypeCheck.fir.kt b/compiler/testData/diagnostics/tests/enum/enumSubjectTypeCheck.fir.kt
new file mode 100644
index 00000000000..c1e21b2b41d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumSubjectTypeCheck.fir.kt
@@ -0,0 +1,40 @@
+// See KT-14705
+
+enum class En { A, B, С }
+
+fun foo() {
+    // nullable variable
+    val en2: Any? = En.A
+    if (en2 is En) {
+        when (en2) {
+            En.A -> {}
+            En.B -> {}
+            En.С -> {}
+        }
+    }
+
+    // not nullable variable
+    val en1: Any = En.A
+    if (en1 is En) {
+        when (en1) {
+            En.A -> {}
+            En.B -> {}
+            En.С -> {}
+        }
+    }
+}
+
+enum class En2 { D, E, F }
+
+fun useEn(x: En) = x
+fun useEn2(x: En2) = x
+
+fun bar(x: Any) {
+    if (x is En && x is En2) {
+        when (x) {
+            En.A -> useEn(x)
+            En2.D -> useEn2(x)
+            else -> {}
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumWithAnnotationKeyword.fir.kt b/compiler/testData/diagnostics/tests/enum/enumWithAnnotationKeyword.fir.kt
new file mode 100644
index 00000000000..2ecf57a0886
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumWithAnnotationKeyword.fir.kt
@@ -0,0 +1,3 @@
+annotation enum class E {
+    D
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/enumWithEmptyName.fir.kt b/compiler/testData/diagnostics/tests/enum/enumWithEmptyName.fir.kt
new file mode 100644
index 00000000000..02cc1dbca97
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/enumWithEmptyName.fir.kt
@@ -0,0 +1,2 @@
+enum class<!SYNTAX!><!> {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/extendingEnumDirectly.fir.kt b/compiler/testData/diagnostics/tests/enum/extendingEnumDirectly.fir.kt
new file mode 100644
index 00000000000..be44ac109a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/extendingEnumDirectly.fir.kt
@@ -0,0 +1,9 @@
+class Test1 : Enum<Test1>("", 0)
+
+class Outer {
+    class Test2 : Enum<Test2>("", 0)
+}
+
+fun outer() {
+    class Test3 : Enum<Test3>("", 0)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/extensionNamedAsEnumEntry.fir.kt b/compiler/testData/diagnostics/tests/enum/extensionNamedAsEnumEntry.fir.kt
new file mode 100644
index 00000000000..7441eca0cfa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/extensionNamedAsEnumEntry.fir.kt
@@ -0,0 +1,8 @@
+enum class E {
+    entry
+}
+
+val Int.entry: Int get() = 42
+val Long.entry: Int get() = 239
+
+val e = E.entry
diff --git a/compiler/testData/diagnostics/tests/enum/ifEnumEntry.fir.kt b/compiler/testData/diagnostics/tests/enum/ifEnumEntry.fir.kt
new file mode 100644
index 00000000000..3995bc0e6fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/ifEnumEntry.fir.kt
@@ -0,0 +1,6 @@
+enum class MyEnum {
+    FIRST,
+    SECOND
+}
+
+fun foo(me: MyEnum): Boolean = if (me is MyEnum.FIRST) true else false
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/importEnumFromJava.fir.kt b/compiler/testData/diagnostics/tests/enum/importEnumFromJava.fir.kt
new file mode 100644
index 00000000000..40fc2379b89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/importEnumFromJava.fir.kt
@@ -0,0 +1,7 @@
+// FILE: test.kt
+
+package test
+
+import java.util.concurrent.TimeUnit.*
+
+val c = SECONDS
diff --git a/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.fir.kt b/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.fir.kt
new file mode 100644
index 00000000000..18fc2855e85
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/incompatibleEnumEntryClasses.fir.kt
@@ -0,0 +1,90 @@
+interface I {
+    fun foo()
+}
+
+enum class E1 : I {
+    A {
+        override fun foo() {
+            this == E2.A
+
+            val q = this
+            when (q) {
+                this -> {}
+                E1.A -> {}
+                E1.B -> {}
+                E2.A -> {}
+                E2.B -> {}
+                else -> {}
+            }
+        }
+    },
+    B {
+        override fun foo() {
+
+        }
+    }
+}
+
+enum class E2 : I {
+    A {
+        override fun foo() {
+
+        }
+    },
+    B {
+        override fun foo() {
+
+        }
+    }
+}
+
+fun foo1(e1: E1, e2: E2) {
+    e1 == e2
+    e1 != e2
+
+    e1 == E2.A
+    E1.B == e2
+
+    E1.A == E2.B
+
+    e1 == E1.A
+    E1.A == e1
+    e2 == E2.B
+    E2.B == e2
+}
+
+fun foo2(e1: E1, e2: E2) {
+    when (e1) {
+        E1.A -> {}
+        E2.A -> {}
+        E2.B -> {}
+        e1 -> {}
+        e2 -> {}
+        else -> {}
+    }
+}
+
+fun foo3(e1: Enum<E1>, e2: Enum<E2>, e: Enum<*>) {
+    e1 == e
+    e1 == e2
+
+    e1 == E1.A
+    e1 == E2.A
+
+    when (e1) {
+        e1 -> {}
+        e2 -> {}
+        e -> {}
+        E1.A -> {}
+        E2.A -> {}
+        else -> {}
+    }
+
+    when (e) {
+        e -> {}
+        e2 -> {}
+        E1.A -> {}
+        E2.A -> {}
+        else -> {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/incompatibleEnums.fir.kt b/compiler/testData/diagnostics/tests/enum/incompatibleEnums.fir.kt
new file mode 100644
index 00000000000..b871cd0fe2a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/incompatibleEnums.fir.kt
@@ -0,0 +1,145 @@
+// !LANGUAGE: -ProhibitComparisonOfIncompatibleEnums
+
+enum class E1 {
+    A, B
+}
+
+enum class E2 {
+    A, B
+}
+
+fun foo1(e1: E1, e2: E2) {
+    e1 == e2
+    e1 != e2
+
+    e1 == E2.A
+    E1.B == e2
+
+    E1.A == E2.B
+
+    e1 == E1.A
+    E1.A == e1
+    e2 == E2.B
+    E2.B == e2
+}
+
+fun foo2(e1: E1, e2: E2) {
+    when (e1) {
+        E1.A -> {}
+        E2.A -> {}
+        E2.B -> {}
+        e1 -> {}
+        e2 -> {}
+        else -> {}
+    }
+}
+
+fun foo3(e1: Enum<E1>, e2: Enum<E2>, e: Enum<*>) {
+    e1 == e
+    e1 == e2
+
+    e1 == E1.A
+    e1 == E2.A
+
+    when (e1) {
+        e1 -> {}
+        e2 -> {}
+        e -> {}
+        E1.A -> {}
+        E2.A -> {}
+        else -> {}
+    }
+
+    when (e) {
+        e -> {}
+        e2 -> {}
+        E1.A -> {}
+        E2.A -> {}
+        else -> {}
+    }
+}
+
+interface MyInterface
+open class MyOpenClass
+
+fun foo4(e1: E1, i: MyInterface, c: MyOpenClass) {
+    e1 == i
+    i == e1
+
+    e1 == c
+    c == e1
+
+    when (e1) {
+        i -> {}
+        c -> {}
+        else -> {}
+    }
+}
+
+enum class E3 : MyInterface { X, Y }
+
+fun foo5(i: MyInterface, a: Any) {
+    E3.X == E3.Y
+    E3.X == i
+    E3.X == a
+}
+
+fun foo6(e1: E1?, e2: E2) {
+    E1.A == null
+    null == E1.A
+    e1 == null
+    null == e1
+
+    e1 == E2.A
+    E2.A == e1
+    e1 == e2
+    e2 == e1
+
+    e2 == null
+    null == e2
+    E1.A == null
+    null == E1.A
+}
+
+fun foo7(e1: E1?, e2: E2?) {
+    e1 == e2 // There should be an IDE-inspection for such cases
+}
+
+fun <T> foo8(e1: E1?, e2: E2, t: T) {
+    e1 == t
+    t == e1
+
+    e2 == t
+    t == e2
+
+    E1.A == t
+    t == E1.A
+}
+
+fun <T, K> foo9(e1: E1?, e2: E2, t: T, k: K) where T : MyInterface, T : MyOpenClass, K : MyInterface {
+    e1 == t
+    t == e1
+
+    e2 == t
+    t == e2
+
+    E1.A == t
+    t == E1.A
+
+    E3.X == t
+
+    E3.X == k
+    k == E3.X
+}
+
+interface Inv<T>
+
+enum class E4 : Inv<Int> { A }
+
+fun foo10(e4: E4, invString: Inv<String>) {
+    e4 == invString
+    invString == e4
+
+    E4.A == invString
+    invString == E4.A
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/incompatibleEnums_1_4.fir.kt b/compiler/testData/diagnostics/tests/enum/incompatibleEnums_1_4.fir.kt
new file mode 100644
index 00000000000..a6e997afaa4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/incompatibleEnums_1_4.fir.kt
@@ -0,0 +1,145 @@
+// !LANGUAGE: +ProhibitComparisonOfIncompatibleEnums
+
+enum class E1 {
+    A, B
+}
+
+enum class E2 {
+    A, B
+}
+
+fun foo1(e1: E1, e2: E2) {
+    e1 == e2
+    e1 != e2
+
+    e1 == E2.A
+    E1.B == e2
+
+    E1.A == E2.B
+
+    e1 == E1.A
+    E1.A == e1
+    e2 == E2.B
+    E2.B == e2
+}
+
+fun foo2(e1: E1, e2: E2) {
+    when (e1) {
+        E1.A -> {}
+            E2.A -> {}
+            E2.B -> {}
+        e1 -> {}
+            e2 -> {}
+        else -> {}
+    }
+}
+
+fun foo3(e1: Enum<E1>, e2: Enum<E2>, e: Enum<*>) {
+    e1 == e
+    e1 == e2
+
+    e1 == E1.A
+    e1 == E2.A
+
+    when (e1) {
+        e1 -> {}
+        e2 -> {}
+        e -> {}
+        E1.A -> {}
+            E2.A -> {}
+        else -> {}
+    }
+
+    when (e) {
+        e -> {}
+        e2 -> {}
+        E1.A -> {}
+        E2.A -> {}
+        else -> {}
+    }
+}
+
+interface MyInterface
+open class MyOpenClass
+
+fun foo4(e1: E1, i: MyInterface, c: MyOpenClass) {
+    e1 == i
+    i == e1
+
+    e1 == c
+    c == e1
+
+    when (e1) {
+            i -> {}
+            c -> {}
+        else -> {}
+    }
+}
+
+enum class E3 : MyInterface { X, Y }
+
+fun foo5(i: MyInterface, a: Any) {
+    E3.X == E3.Y
+    E3.X == i
+    E3.X == a
+}
+
+fun foo6(e1: E1?, e2: E2) {
+    E1.A == null
+    null == E1.A
+    e1 == null
+    null == e1
+
+    e1 == E2.A
+    E2.A == e1
+    e1 == e2
+    e2 == e1
+
+    e2 == null
+    null == e2
+    E1.A == null
+    null == E1.A
+}
+
+fun foo7(e1: E1?, e2: E2?) {
+    e1 == e2 // There should be an IDE-inspection for such cases
+}
+
+fun <T> foo8(e1: E1?, e2: E2, t: T) {
+    e1 == t
+    t == e1
+
+    e2 == t
+    t == e2
+
+    E1.A == t
+    t == E1.A
+}
+
+fun <T, K> foo9(e1: E1?, e2: E2, t: T, k: K) where T : MyInterface, T : MyOpenClass, K : MyInterface {
+    e1 == t
+    t == e1
+
+    e2 == t
+    t == e2
+
+    E1.A == t
+    t == E1.A
+
+    E3.X == t
+
+    E3.X == k
+    k == E3.X
+}
+
+interface Inv<T>
+
+enum class E4 : Inv<Int> { A }
+
+fun foo10(e4: E4, invString: Inv<String>) {
+    e4 == invString
+    invString == e4
+
+    E4.A == invString
+    invString == E4.A
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/inheritFromEnumEntry.fir.kt b/compiler/testData/diagnostics/tests/enum/inheritFromEnumEntry.fir.kt
new file mode 100644
index 00000000000..46f04bf9900
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inheritFromEnumEntry.fir.kt
@@ -0,0 +1,5 @@
+enum class E {
+    ENTRY
+}
+
+class A : E.ENTRY
diff --git a/compiler/testData/diagnostics/tests/enum/inheritanceFromEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/inheritanceFromEnum.fir.kt
new file mode 100644
index 00000000000..937cb42fbfe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inheritanceFromEnum.fir.kt
@@ -0,0 +1,13 @@
+// FILE: MyJavaEnum.java
+public enum MyJavaEnum {}
+
+// FILE: test.kt
+open enum class MyEnum() {
+    A()
+}
+
+enum class MyEnum2() {}
+
+class MyClass(): <!INAPPLICABLE_CANDIDATE!>MyEnum2<!>() {}
+
+class MyClass2(): <!UNRESOLVED_REFERENCE!>MyJavaEnum<!>() {}
diff --git a/compiler/testData/diagnostics/tests/enum/inline.fir.kt b/compiler/testData/diagnostics/tests/enum/inline.fir.kt
new file mode 100644
index 00000000000..29e488c6785
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inline.fir.kt
@@ -0,0 +1,3 @@
+enum class My {
+    inline
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/existingClassObject.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/existingClassObject.fir.kt
new file mode 100644
index 00000000000..9bd71186e81
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/existingClassObject.fir.kt
@@ -0,0 +1,19 @@
+class A {
+    enum class E {
+        ENTRY
+    }
+    
+    companion object {
+    }
+}
+
+
+
+class B {
+    companion object {
+    }
+    
+    enum class E {
+        ENTRY
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideClass.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideClass.fir.kt
new file mode 100644
index 00000000000..27369f8033f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideClass.fir.kt
@@ -0,0 +1,5 @@
+class A {
+    enum class E {
+        ENTRY
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideClassObject.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideClassObject.fir.kt
new file mode 100644
index 00000000000..a95430c721f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideClassObject.fir.kt
@@ -0,0 +1,7 @@
+class A {
+    companion object {
+        enum class E {
+            ENTRY
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideEnum.fir.kt
new file mode 100644
index 00000000000..e85746eb8eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideEnum.fir.kt
@@ -0,0 +1,7 @@
+enum class E {
+    ABC;
+    
+    enum class F {
+        DEF
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideEnumEntry_after.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideEnumEntry_after.fir.kt
new file mode 100644
index 00000000000..df48fc37e3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideEnumEntry_after.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +NestedClassesInEnumEntryShouldBeInner
+
+enum class E {
+    ABC {
+        enum class F {
+            DEF
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideEnumEntry_before.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideEnumEntry_before.fir.kt
new file mode 100644
index 00000000000..e1ac99322ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideEnumEntry_before.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: -NestedClassesInEnumEntryShouldBeInner
+
+enum class E {
+    ABC {
+        enum class F {
+            DEF
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideInnerClassNotAllowed.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideInnerClassNotAllowed.fir.kt
new file mode 100644
index 00000000000..5adc47b7eb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideInnerClassNotAllowed.fir.kt
@@ -0,0 +1,7 @@
+class A {
+    inner class B {
+        enum class E {
+            ENTRY
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideObject.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideObject.fir.kt
new file mode 100644
index 00000000000..80f679f8167
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideObject.fir.kt
@@ -0,0 +1,5 @@
+object A {
+    enum class E {
+        ENTRY
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/insideTrait.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/insideTrait.fir.kt
new file mode 100644
index 00000000000..5d04181c73b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/insideTrait.fir.kt
@@ -0,0 +1,5 @@
+interface A {
+    enum class E {
+        ENTRY
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/redeclarationInClassObject.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/redeclarationInClassObject.fir.kt
new file mode 100644
index 00000000000..5c974e726e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/redeclarationInClassObject.fir.kt
@@ -0,0 +1,11 @@
+class A {
+    enum class E {
+        ENTRY
+    }
+    
+    companion object {
+        enum class E {
+            ENTRY2
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/inner/twoEnums.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/twoEnums.fir.kt
new file mode 100644
index 00000000000..fbf22f500c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/twoEnums.fir.kt
@@ -0,0 +1,4 @@
+class A {
+    enum class E { ABC }
+    enum class F { DEF }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/inner/twoEnumsInClassObjectAndInnerClass.fir.kt b/compiler/testData/diagnostics/tests/enum/inner/twoEnumsInClassObjectAndInnerClass.fir.kt
new file mode 100644
index 00000000000..49cedfbdd6f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/inner/twoEnumsInClassObjectAndInnerClass.fir.kt
@@ -0,0 +1,9 @@
+class A {
+    companion object {
+        enum class E { ENTRY }  // OK
+    }
+    
+    inner class B {
+        enum class E { ENTRY }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/interfaceWithEnumKeyword.fir.kt b/compiler/testData/diagnostics/tests/enum/interfaceWithEnumKeyword.fir.kt
new file mode 100644
index 00000000000..8db080692bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/interfaceWithEnumKeyword.fir.kt
@@ -0,0 +1,8 @@
+enum interface Some {
+    // Enum part
+    D;
+
+    // Interface like part
+    fun test()
+    val foo: Int
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/isEnumEntry.fir.kt b/compiler/testData/diagnostics/tests/enum/isEnumEntry.fir.kt
new file mode 100644
index 00000000000..28becfcb3db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/isEnumEntry.fir.kt
@@ -0,0 +1,6 @@
+enum class MyEnum {
+    FIRST,
+    SECOND
+}
+
+fun foo(me: MyEnum): Boolean = me is MyEnum.FIRST
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/javaEnumValueOfMethod.fir.kt b/compiler/testData/diagnostics/tests/enum/javaEnumValueOfMethod.fir.kt
new file mode 100644
index 00000000000..971bb3fec1e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/javaEnumValueOfMethod.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+// FILE: A.java
+public enum A {
+    ENTRY;
+}
+
+// FILE: test.kt
+fun main() {
+    checkSubtype<A>(A.valueOf("ENTRY"))
+}
diff --git a/compiler/testData/diagnostics/tests/enum/javaEnumValuesMethod.fir.kt b/compiler/testData/diagnostics/tests/enum/javaEnumValuesMethod.fir.kt
new file mode 100644
index 00000000000..6089eef7c3c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/javaEnumValuesMethod.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+// FILE: A.java
+public enum A {
+    ENTRY,
+    ANOTHER;
+}
+
+// FILE: test.kt
+fun main() {
+     checkSubtype<Array<A>>(A.values())
+}
diff --git a/compiler/testData/diagnostics/tests/enum/javaEnumWithAbstractFun.fir.kt b/compiler/testData/diagnostics/tests/enum/javaEnumWithAbstractFun.fir.kt
new file mode 100644
index 00000000000..d6a3800ebc8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/javaEnumWithAbstractFun.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+// FILE: A.java
+public enum A {
+
+    ENTRY {
+        public String s() {
+            return "s";
+        }
+    };
+    public abstract String s();
+}
+
+// FILE: test.kt
+fun main() {
+    checkSubtype<String?>(A.ENTRY.s())
+}
diff --git a/compiler/testData/diagnostics/tests/enum/javaEnumWithFuns.fir.kt b/compiler/testData/diagnostics/tests/enum/javaEnumWithFuns.fir.kt
new file mode 100644
index 00000000000..7d6399171d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/javaEnumWithFuns.fir.kt
@@ -0,0 +1,16 @@
+// FILE: A.java
+public enum A {
+    ENTRY,
+    ANOTHER;
+    
+    public String s() {
+        return "";
+    }
+}
+
+// FILE: test.kt
+
+fun main() {
+    val c = A.ENTRY
+    c.s()
+}
diff --git a/compiler/testData/diagnostics/tests/enum/javaEnumWithNameClashing.fir.kt b/compiler/testData/diagnostics/tests/enum/javaEnumWithNameClashing.fir.kt
new file mode 100644
index 00000000000..d06fca45d28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/javaEnumWithNameClashing.fir.kt
@@ -0,0 +1,15 @@
+// FILE: A.java
+public enum A {
+    ENTRY,
+    ANOTHER;
+
+    public String ENTRY = "";
+}
+
+// FILE: test.kt
+
+fun main() {
+    val c: A = A.ENTRY
+    val c2: String? = c.<!AMBIGUITY!>ENTRY<!>
+    val c3: String? = A.ANOTHER.<!AMBIGUITY!>ENTRY<!>
+}
diff --git a/compiler/testData/diagnostics/tests/enum/javaEnumWithProperty.fir.kt b/compiler/testData/diagnostics/tests/enum/javaEnumWithProperty.fir.kt
new file mode 100644
index 00000000000..5ab0ebf77dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/javaEnumWithProperty.fir.kt
@@ -0,0 +1,19 @@
+// FILE: A.java
+public enum A {
+    ENTRY("1"),
+    ANOTHER("2");
+
+    public String s;
+
+    private A(String s) {
+        this.s = s;
+    }
+}
+
+// FILE: test.kt
+
+fun main() {
+    val c = A.ENTRY
+    c.s
+    A.ANOTHER.s
+}
diff --git a/compiler/testData/diagnostics/tests/enum/kt2834.fir.kt b/compiler/testData/diagnostics/tests/enum/kt2834.fir.kt
new file mode 100644
index 00000000000..8144143dd11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/kt2834.fir.kt
@@ -0,0 +1,6 @@
+private enum class MethodKind {
+    INSTANCE,
+    STATIC
+}
+
+private fun MethodKind.hasThis() = this == MethodKind.INSTANCE
diff --git a/compiler/testData/diagnostics/tests/enum/kt8972_cloneNotAllowed.fir.kt b/compiler/testData/diagnostics/tests/enum/kt8972_cloneNotAllowed.fir.kt
new file mode 100644
index 00000000000..6a63b936836
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/kt8972_cloneNotAllowed.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+enum class E : Cloneable {
+    A;
+    override fun clone(): Any {
+        return super.clone()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/enum/localEnums.fir.kt b/compiler/testData/diagnostics/tests/enum/localEnums.fir.kt
new file mode 100644
index 00000000000..22a4801d5a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/localEnums.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun foo() {
+    enum class A {
+        FOO,
+        BAR
+    }
+    val foo = A.<!UNRESOLVED_REFERENCE!>FOO<!>
+    val b = object {
+        enum class B {}
+    }
+    class C {
+        enum class D {}
+    }
+    val f = {
+        enum class E {}
+    }
+
+    enum class<!SYNTAX!><!> {}
+}
diff --git a/compiler/testData/diagnostics/tests/enum/modifiersOnEnumEntry.fir.kt b/compiler/testData/diagnostics/tests/enum/modifiersOnEnumEntry.fir.kt
new file mode 100644
index 00000000000..d5d8bc23a3f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/modifiersOnEnumEntry.fir.kt
@@ -0,0 +1,23 @@
+enum class E {
+    public final SUBCLASS {
+        fun foo() {}
+    },
+
+    public PUBLIC,
+    protected PROTECTED,
+    private PRIVATE,
+    internal INTERNAL,
+
+    abstract ABSTRACT,
+    open OPEN,
+    override OVERRIDE,
+    final FINAL,
+
+    inner INNER,
+    annotation ANNOTATION,
+    enum ENUM,
+    out OUT,
+    in IN,
+    vararg VARARG,
+    reified REIFIED
+}
diff --git a/compiler/testData/diagnostics/tests/enum/multipleConstructors.fir.kt b/compiler/testData/diagnostics/tests/enum/multipleConstructors.fir.kt
new file mode 100644
index 00000000000..70a2c379ca7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/multipleConstructors.fir.kt
@@ -0,0 +1,8 @@
+enum class E(val x: Int, val y: Int) {
+    A(1, 2),
+    B(1),
+    C; // no constructor call needed even here
+
+    constructor(): this(0, 0)
+    constructor(x: Int): this(x, 0)
+}
diff --git a/compiler/testData/diagnostics/tests/enum/openMemberInEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/openMemberInEnum.fir.kt
new file mode 100644
index 00000000000..7f2e397e0fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/openMemberInEnum.fir.kt
@@ -0,0 +1,17 @@
+enum class EnumWithOpenMembers {
+    E1 {
+        override fun foo() = 1
+        override val bar: String = "a"
+    },
+
+    E2 {
+        override fun f() = 3
+        override val b = 4
+    };
+
+    open fun foo() = 1
+    open val bar: String = ""
+
+    fun f() = 2
+    val b = 3
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/enum/overrideFinalEnumMethods.fir.kt b/compiler/testData/diagnostics/tests/enum/overrideFinalEnumMethods.fir.kt
new file mode 100644
index 00000000000..69b11a657d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/overrideFinalEnumMethods.fir.kt
@@ -0,0 +1,11 @@
+enum class E {
+    ENTRY;
+
+    override val name: String = "lol"
+    override val ordinal: Int = 0
+
+    override fun compareTo(other: E) = -1
+
+    override fun equals(other: Any?) = true
+    override fun hashCode() = -1
+}
diff --git a/compiler/testData/diagnostics/tests/enum/starImportNestedClassAndEntries.fir.kt b/compiler/testData/diagnostics/tests/enum/starImportNestedClassAndEntries.fir.kt
new file mode 100644
index 00000000000..b2b9ba97aa3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/starImportNestedClassAndEntries.fir.kt
@@ -0,0 +1,24 @@
+// FILE: E.kt
+package foo
+
+enum class E {
+    ENTRY,
+    ANOTHER;
+
+    class Nested {
+        companion object {
+            fun foo() = 42
+        }
+    }
+}
+
+// FILE: main.kt
+package bar
+
+import foo.E.*
+
+fun f1() = ENTRY
+fun f2() = ANOTHER
+fun f3() = Nested()
+fun f4() = Nested.foo()
+fun f5() = values()
diff --git a/compiler/testData/diagnostics/tests/enum/typeParametersInEnum.fir.kt b/compiler/testData/diagnostics/tests/enum/typeParametersInEnum.fir.kt
new file mode 100644
index 00000000000..a2d2d1dc0a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/typeParametersInEnum.fir.kt
@@ -0,0 +1,7 @@
+// KT-5696 Prohibit type parameters for enum classes
+
+package bug
+
+public enum class Foo<T> {
+    A()
+}
diff --git a/compiler/testData/diagnostics/tests/enum/valuesValueOfAndEntriesAccessibility.fir.kt b/compiler/testData/diagnostics/tests/enum/valuesValueOfAndEntriesAccessibility.fir.kt
new file mode 100644
index 00000000000..c023e705a4a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/valuesValueOfAndEntriesAccessibility.fir.kt
@@ -0,0 +1,18 @@
+enum class E {
+    ENTRY;
+
+    companion object {
+        fun foo(): E = ENTRY
+        fun bar(): Array<E> = <!UNRESOLVED_REFERENCE!>values<!>()
+        fun baz(): E = <!UNRESOLVED_REFERENCE!>valueOf<!>("ENTRY")
+        val valuez = <!UNRESOLVED_REFERENCE!>values<!>()
+    }
+
+    fun oof(): E = ENTRY
+    fun rab(): Array<E> = values()
+    fun zab(): E = valueOf("ENTRY")
+}
+
+fun foo() = E.ENTRY
+fun bar() = E.values()
+fun baz() = E.valueOf("ENTRY")
diff --git a/compiler/testData/diagnostics/tests/enum/wrongUnitializedEnumCompanion.fir.kt b/compiler/testData/diagnostics/tests/enum/wrongUnitializedEnumCompanion.fir.kt
new file mode 100644
index 00000000000..d8913f128a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/enum/wrongUnitializedEnumCompanion.fir.kt
@@ -0,0 +1,9 @@
+// See KT-20959
+
+enum class Foo {;
+    companion object  {
+        val x = foo() // there should be no UNINITIALIZED_ENUM_COMPANION
+
+        private fun foo() = "OK"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/evaluate/binaryMinusDepOnExpType.fir.kt b/compiler/testData/diagnostics/tests/evaluate/binaryMinusDepOnExpType.fir.kt
new file mode 100644
index 00000000000..fdf5c00a2af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/binaryMinusDepOnExpType.fir.kt
@@ -0,0 +1,30 @@
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(1 - 1)
+    fooInt(1 - 1.toInt())
+    fooInt(1 - 1.toByte())
+    <!INAPPLICABLE_CANDIDATE!>fooInt<!>(1 - 1.toLong())
+    fooInt(1 - 1.toShort())
+
+    fooByte(1 - 1)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(1 - 1.toInt())
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(1 - 1.toByte())
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(1 - 1.toLong())
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(1 - 1.toShort())
+
+    fooLong(1 - 1)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(1 - 1.toInt())
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(1 - 1.toByte())
+    fooLong(1 - 1.toLong())
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(1 - 1.toShort())
+
+    fooShort(1 - 1)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(1 - 1.toInt())
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(1 - 1.toByte())
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(1 - 1.toLong())
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(1 - 1.toShort())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/binaryMinusIndepWoExpType.fir.kt b/compiler/testData/diagnostics/tests/evaluate/binaryMinusIndepWoExpType.fir.kt
new file mode 100644
index 00000000000..15c7b377c16
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/binaryMinusIndepWoExpType.fir.kt
@@ -0,0 +1,36 @@
+val p1 = 1 - 1
+val p2 = 1 - 1.toLong()
+val p3 = 1 - 1.toByte()
+val p4 = 1 - 1.toInt()
+val p5 = 1 - 1.toShort()
+
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(p1)
+    <!INAPPLICABLE_CANDIDATE!>fooInt<!>(p2)
+    fooInt(p3)
+    fooInt(p4)
+    fooInt(p5)
+
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p1)
+    fooLong(p2)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p3)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p4)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p5)
+
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p1)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p2)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p3)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p4)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p5)
+
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p1)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p2)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p3)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p4)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p5)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/binaryMinusIndependentExpType.fir.kt b/compiler/testData/diagnostics/tests/evaluate/binaryMinusIndependentExpType.fir.kt
new file mode 100644
index 00000000000..f7f924c32ef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/binaryMinusIndependentExpType.fir.kt
@@ -0,0 +1,24 @@
+val p1: Int = 1 - 1
+val p2: Long = 1 - 1
+val p3: Byte = 1 - 1
+val p4: Short = 1 - 1
+
+val l1: Long = 1 - 1.toLong()
+val l2: Byte = 1 - 1.toLong()
+val l3: Int = 1 - 1.toLong()
+val l4: Short = 1 - 1.toLong()
+
+val b1: Byte = 1 - 1.toByte()
+val b2: Int = 1 - 1.toByte()
+val b3: Long = 1 - 1.toByte()
+val b4: Short = 1 - 1.toByte()
+
+val i1: Byte = 1 - 1.toInt()
+val i2: Int = 1 - 1.toInt()
+val i3: Long = 1 - 1.toInt()
+val i4: Short = 1 - 1.toInt()
+
+val s1: Byte = 1 - 1.toShort()
+val s2: Int = 1 - 1.toShort()
+val s3: Long = 1 - 1.toShort()
+val s4: Short = 1 - 1.toShort()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/divisionByZero.fir.kt b/compiler/testData/diagnostics/tests/evaluate/divisionByZero.fir.kt
new file mode 100644
index 00000000000..3f87f1f39a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/divisionByZero.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+val a1 = 0
+val a2 = 1 / 0
+val a3 = 1 / a1
+val a4 = 1 / a2
+val a5 = 2 * (1 / 0)
+
+val a6 = 1.div(0)
+val a7 = 1.div(a1)
+val a8 = 1.div(a2)
+val a9 = 2 * (1.div(0))
+
+val b1: Byte = 1 / 0
+@Ann(1 / 0) val b2 = 1
+
+annotation class Ann(val i : Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/float.fir.kt b/compiler/testData/diagnostics/tests/evaluate/float.fir.kt
new file mode 100644
index 00000000000..67f8b0c5692
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/float.fir.kt
@@ -0,0 +1,10 @@
+val a1: Float = 1F
+val a2: Float = 1.0F
+val a3: Float = 1e-1F
+val a4: Float = 1.0e-1F
+
+val b5: Float = 1f
+val b6: Float = 1.0f
+val b7: Float = 1e-1f
+val b8: Float = 1.0e-1f
+
diff --git a/compiler/testData/diagnostics/tests/evaluate/floatLiteralOutOfRange.fir.kt b/compiler/testData/diagnostics/tests/evaluate/floatLiteralOutOfRange.fir.kt
new file mode 100644
index 00000000000..3f24b603407
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/floatLiteralOutOfRange.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_EXPRESSION
+
+fun test() {
+    1.2E400F
+    1.2E-400F
+    11111111111111111111111111111111111111111111111111111111111111111F
+    0.000000000000000000000000000000000000000000000000000000000000001F
+    0.000000000000000000000000000000000000001000000000000000000000000F
+
+    1.2E400f
+    1.2E-400f
+    11111111111111111111111111111111111111111111111111111111111111111f
+    0.000000000000000000000000000000000000000000000000000000000000001f
+    0.000000000000000000000000000000000000001000000000000000000000000f
+
+    val d1: Double = 1.2E400
+    val d2: Double = 1.2E-400
+    val d3: Double = 11111111111111111111111111111111111111111111111111111111111111111.0
+    val d4: Double = 0.000000000000000000000000000000000000000000000000000000000000001
+    val d5: Double = 0.000000000000000000000000000000000000001000000000000000000000000
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/infixFunOverBuiltinMemberInConst.fir.kt b/compiler/testData/diagnostics/tests/evaluate/infixFunOverBuiltinMemberInConst.fir.kt
new file mode 100644
index 00000000000..d9361ac8aff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/infixFunOverBuiltinMemberInConst.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+infix fun Int.rem(other: Int) = 10
+infix operator fun Int.minus(other: Int): Int = 20
+
+const val a1 = (-5) rem 2
+const val a2 = (-5).rem(2)
+
+const val b1 = 5 minus 3
+const val b2 = 5.minus(3)
diff --git a/compiler/testData/diagnostics/tests/evaluate/inlineClasses/constructorOfUnsignedType.fir.kt b/compiler/testData/diagnostics/tests/evaluate/inlineClasses/constructorOfUnsignedType.fir.kt
new file mode 100644
index 00000000000..efab6641d11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/inlineClasses/constructorOfUnsignedType.fir.kt
@@ -0,0 +1,44 @@
+// !LANGUAGE: +InlineClasses
+// JAVAC_SKIP
+
+// FILE: uint.kt
+
+package kotlin
+
+inline class UByte(private val b: Byte)
+inline class UShort(private val s: Short)
+inline class UInt(private val i: Int)
+inline class ULong(private val l: Long)
+
+// FILE: test.kt
+
+annotation class AnnoUB(val ub0: UByte, val ub1: UByte)
+annotation class AnnoUS(val us0: UShort, val us1: UShort)
+annotation class AnnoUI(val ui0: UInt, val ui1: UInt, val ui2: UInt, val ui3: UInt)
+annotation class AnnoUL(val ul0: ULong, val ul1: ULong)
+
+const val ub0 = <!UNRESOLVED_REFERENCE!>UByte<!>(1)
+const val us0 = <!UNRESOLVED_REFERENCE!>UShort<!>(2)
+const val ul0 = <!UNRESOLVED_REFERENCE!>ULong<!>(3)
+
+const val ui0 = <!UNRESOLVED_REFERENCE!>UInt<!>(-1)
+const val ui1 = <!UNRESOLVED_REFERENCE!>UInt<!>(0)
+const val ui2 = <!UNRESOLVED_REFERENCE!>UInt<!>(40 + 2)
+
+@AnnoUB(<!UNRESOLVED_REFERENCE!>UByte<!>(1), ub0)
+fun f0() {}
+
+@AnnoUS(<!UNRESOLVED_REFERENCE!>UShort<!>(2 + 5), us0)
+fun f1() {}
+
+@AnnoUI(ui0, ui1, ui2, <!UNRESOLVED_REFERENCE!>UInt<!>(100))
+fun f2() {}
+
+@AnnoUL(ul0, <!UNRESOLVED_REFERENCE!>ULong<!>(5))
+fun f3() {}
+
+const val explicit: UInt = <!UNRESOLVED_REFERENCE!>UInt<!>(2)
+
+const val nullable: UInt? = <!UNRESOLVED_REFERENCE!>UInt<!>(3)
+
+annotation class NullableAnno(val u: UInt?)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/intOverflow.fir.kt b/compiler/testData/diagnostics/tests/evaluate/intOverflow.fir.kt
new file mode 100644
index 00000000000..741f62a305a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/intOverflow.fir.kt
@@ -0,0 +1,77 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+val intMaxValue: Int = 0x7fffffff
+val intMinValue: Int = 1 shl 31
+
+val a3: Int = intMaxValue + 1 - 10
+val a4: Int = intMaxValue + 1 + 10
+val i2: Int = intMaxValue - 1 + 2
+val i3: Int = intMaxValue - intMinValue
+val i4: Int = -intMinValue
+val i5: Int = intMinValue - 1
+val i6: Int = intMinValue - intMaxValue
+val i7: Int = intMinValue + intMaxValue
+val i8: Int = -intMaxValue
+val i10: Int = intMinValue * -1
+val i11: Int = intMinValue * 2
+val i12: Int = intMaxValue * -2
+val i13: Int = intMaxValue * -1
+val i15: Int = intMinValue / -1
+val l20: Int = 30 * 24 * 60 * 60 * 1000
+val l21: Int = intMinValue - intMinValue
+val l22: Int = intMinValue + -intMinValue
+val l23: Int = intMaxValue + -intMinValue
+val l24: Int = (-1).mod(5)
+val l25: Int = (-1).rem(5)
+val l26: Int = (-1) % 5
+
+
+fun foo() {
+    val a3: Int = intMaxValue + 1 - 10
+    val a4: Int = intMaxValue + 1 + 10
+    val i2: Int = intMaxValue - 1 + 2
+    val i3: Int = intMaxValue - intMinValue
+    val i4: Int = -intMinValue
+    val i5: Int = intMinValue - 1
+    val i6: Int = intMinValue - intMaxValue
+    val i7: Int = intMinValue + intMaxValue
+    val i8: Int = -intMaxValue
+    val i10: Int = intMinValue * -1
+    val i11: Int = intMinValue * 2
+    val i12: Int = intMaxValue * -2
+    val i13: Int = intMaxValue * -1
+    val i15: Int = intMinValue / -1
+    val l20: Int = 30 * 24 * 60 * 60 * 1000
+    val l21: Int = intMinValue - intMinValue
+    val l22: Int = intMinValue + -intMinValue
+    val l23: Int = intMaxValue + -intMinValue
+    val l24: Int = (-1).mod(5)
+    val l25: Int = (-1).rem(5)
+    val l26: Int = (-1) % 5
+}
+
+class A {
+    fun foo() {
+        val a3: Int = intMaxValue + 1 - 10
+        val a4: Int = intMaxValue + 1 + 10
+        val i2: Int = intMaxValue - 1 + 2
+        val i3: Int = intMaxValue - intMinValue
+        val i4: Int = -intMinValue
+        val i5: Int = intMinValue - 1
+        val i6: Int = intMinValue - intMaxValue
+        val i7: Int = intMinValue + intMaxValue
+        val i8: Int = -intMaxValue
+        val i10: Int = intMinValue * -1
+        val i11: Int = intMinValue * 2
+        val i12: Int = intMaxValue * -2
+        val i13: Int = intMaxValue * -1
+        val i15: Int = intMinValue / -1
+        val l20: Int = 30 * 24 * 60 * 60 * 1000
+        val l21: Int = intMinValue - intMinValue
+        val l22: Int = intMinValue + -intMinValue
+        val l23: Int = intMaxValue + -intMinValue
+        val l24: Int = (-1).mod(5)
+        val l25: Int = (-1).rem(5)
+        val l26: Int = (-1) % 5
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/intOverflowWithJavaProperties.fir.kt b/compiler/testData/diagnostics/tests/evaluate/intOverflowWithJavaProperties.fir.kt
new file mode 100644
index 00000000000..608b83b7c28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/intOverflowWithJavaProperties.fir.kt
@@ -0,0 +1,14 @@
+// FILE: Test.java
+public class Test {
+    public static int i1 = Integer.MAX_VALUE;
+    public static final int i2 = Integer.MAX_VALUE;
+    public final int i3 = Integer.MAX_VALUE;
+    public int i4 = Integer.MAX_VALUE;
+}
+
+
+// FILE: A.kt
+val a1: Int = Test.i1 + 1
+val a2: Int = Test.i2 + 1
+val a3: Int = Test().i3 + 1
+val a4: Int = Test().i4 + 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/integer.fir.kt b/compiler/testData/diagnostics/tests/evaluate/integer.fir.kt
new file mode 100644
index 00000000000..329bb5d10c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/integer.fir.kt
@@ -0,0 +1,10 @@
+val a1: Int = 1L
+val a2: Int = 0x1L
+val a3: Int = 0X1L
+val a4: Int = 0b1L
+val a5: Int = 0B1L
+val a6: Long = 1L
+val a7: Long = 0x1L
+val a8: Long = 0X1L
+val a9: Long = 0b1L
+val a10: Long = 0B1L
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/logicWithNumber.fir.kt b/compiler/testData/diagnostics/tests/evaluate/logicWithNumber.fir.kt
new file mode 100644
index 00000000000..6c4ca0c41ef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/logicWithNumber.fir.kt
@@ -0,0 +1,8 @@
+fun bar() {
+    false and false
+}
+
+// See exception in KT-13421
+fun foo() {
+    42 and false
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/longOverflow.fir.kt b/compiler/testData/diagnostics/tests/evaluate/longOverflow.fir.kt
new file mode 100644
index 00000000000..ef3d9841142
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/longOverflow.fir.kt
@@ -0,0 +1,65 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+val longMaxValue: Long = 0x7fffffffffffffff
+val longMinValue: Long = -longMaxValue - 1
+val intMaxValue: Int = 0x7fffffff
+val intMinValue: Int = 1 shl 31
+
+val a2: Long = longMinValue - 10
+
+val l1: Long = longMaxValue + 1
+val l2: Long = longMaxValue - 1 + 2
+val l3: Long = longMaxValue - longMinValue
+val l4: Long = -longMinValue
+val l5: Long = longMinValue - 1
+val l6: Long = longMinValue - longMaxValue
+val l7: Long = longMinValue + longMaxValue
+val l8: Long = -longMaxValue
+val l10: Long = -intMinValue.toLong()
+val l11: Long = -1 + intMinValue.toLong()
+val l12: Long = longMinValue * intMinValue
+val l13: Long = longMinValue * -1
+val l14: Long = longMinValue * 2
+val l15: Long = longMaxValue * -2
+val l16: Long = intMinValue.toLong() * -1
+val l19: Long = longMinValue / -1
+
+fun foo() {
+    val l1: Long = longMaxValue + 1
+    val l2: Long = longMaxValue - 1 + 2
+    val l3: Long = longMaxValue - longMinValue
+    val l4: Long = -longMinValue
+    val l5: Long = longMinValue - 1
+    val l6: Long = longMinValue - longMaxValue
+    val l7: Long = longMinValue + longMaxValue
+    val l8: Long = -longMaxValue
+    val l10: Long = -intMinValue.toLong()
+    val l11: Long = -1 + intMinValue.toLong()
+    val l12: Long = longMinValue * intMinValue
+    val l13: Long = longMinValue * -1
+    val l14: Long = longMinValue * 2
+    val l15: Long = longMaxValue * -2
+    val l16: Long = intMinValue.toLong() * -1
+    val l19: Long = longMinValue / -1
+}
+
+class A {
+    fun foo() {
+        val l1: Long = longMaxValue + 1
+        val l2: Long = longMaxValue - 1 + 2
+        val l3: Long = longMaxValue - longMinValue
+        val l4: Long = -longMinValue
+        val l5: Long = longMinValue - 1
+        val l6: Long = longMinValue - longMaxValue
+        val l7: Long = longMinValue + longMaxValue
+        val l8: Long = -longMaxValue
+        val l10: Long = -intMinValue.toLong()
+        val l11: Long = -1 + intMinValue.toLong()
+        val l12: Long = longMinValue * intMinValue
+        val l13: Long = longMinValue * -1
+        val l14: Long = longMinValue * 2
+        val l15: Long = longMaxValue * -2
+        val l16: Long = intMinValue.toLong() * -1
+        val l19: Long = longMinValue / -1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/noOverflowWithZero.fir.kt b/compiler/testData/diagnostics/tests/evaluate/noOverflowWithZero.fir.kt
new file mode 100644
index 00000000000..0e97797cf5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/noOverflowWithZero.fir.kt
@@ -0,0 +1,11 @@
+val zero = 0
+
+fun test() {
+    -0
+    -0L
+    -0.0
+    -(1 - 1)
+    -zero
+
+    +0
+}
diff --git a/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperations.fir.kt b/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperations.fir.kt
new file mode 100644
index 00000000000..3dbdd578b6c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperations.fir.kt
@@ -0,0 +1,26 @@
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(1 + 1)
+    fooByte(1 + 1)
+    fooLong(1 + 1)
+    fooShort(1 + 1)
+
+    fooInt(1 * 1)
+    fooByte(1 * 1)
+    fooLong(1 * 1)
+    fooShort(1 * 1)
+
+    fooInt(1 / 1)
+    fooByte(1 / 1)
+    fooLong(1 / 1)
+    fooShort(1 / 1)
+
+    fooInt(1 % 1)
+    fooByte(1 % 1)
+    fooLong(1 % 1)
+    fooShort(1 % 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperationsCall.fir.kt b/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperationsCall.fir.kt
new file mode 100644
index 00000000000..3133c5b29d7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperationsCall.fir.kt
@@ -0,0 +1,31 @@
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(1.plus(1))
+    fooByte(1.plus(1))
+    fooLong(1.plus(1))
+    fooShort(1.plus(1))
+
+    fooInt(1.times(1))
+    fooByte(1.times(1))
+    fooLong(1.times(1))
+    fooShort(1.times(1))
+
+    fooInt(1.div(1))
+    fooByte(1.div(1))
+    fooLong(1.div(1))
+    fooShort(1.div(1))
+
+    fooInt(1.mod(1))
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(1.mod(1))
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(1.mod(1))
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(1.mod(1))
+
+    fooInt(1.rem(1))
+    fooByte(1.rem(1))
+    fooLong(1.rem(1))
+    fooShort(1.rem(1))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperationsInfixCall.fir.kt b/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperationsInfixCall.fir.kt
new file mode 100644
index 00000000000..8a597af0b82
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/numberBinaryOperationsInfixCall.fir.kt
@@ -0,0 +1,31 @@
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(1 plus 1)
+    fooByte(1 plus 1)
+    fooLong(1 plus 1)
+    fooShort(1 plus 1)
+
+    fooInt(1 times 1)
+    fooByte(1 times 1)
+    fooLong(1 times 1)
+    fooShort(1 times 1)
+
+    fooInt(1 div 1)
+    fooByte(1 div 1)
+    fooLong(1 div 1)
+    fooShort(1 div 1)
+
+    fooInt(1 mod 1)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(1 mod 1)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(1 mod 1)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(1 mod 1)
+
+    fooInt(1 rem 1)
+    fooByte(1 rem 1)
+    fooLong(1 rem 1)
+    fooShort(1 rem 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/otherOverflow.fir.kt b/compiler/testData/diagnostics/tests/evaluate/otherOverflow.fir.kt
new file mode 100644
index 00000000000..566394d268a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/otherOverflow.fir.kt
@@ -0,0 +1,2 @@
+val a1: Int = 32000.toShort() * 32000.toShort() * 32000.toShort()
+val a2: Int = 128.toByte() * 128.toByte() * 128.toByte() * 128.toByte() * 128.toByte()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/parentesized.fir.kt b/compiler/testData/diagnostics/tests/evaluate/parentesized.fir.kt
new file mode 100644
index 00000000000..1b35f47790b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/parentesized.fir.kt
@@ -0,0 +1,12 @@
+val p1: Byte = (1 + 2) * 2
+val p2: Short = (1 + 2) * 2
+val p3: Int = (1 + 2) * 2
+val p4: Long = (1 + 2) * 2
+
+val b1: Byte = (1.toByte() + 2) * 2
+val b2: Short = (1.toShort() + 2) * 2
+val b3: Int = (1.toInt() + 2) * 2
+val b4: Long = (1.toLong() + 2) * 2
+
+val i1: Int = (1.toByte() + 2) * 2
+val i2: Int = (1.toShort() + 2) * 2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/qualifiedExpressions.fir.kt b/compiler/testData/diagnostics/tests/evaluate/qualifiedExpressions.fir.kt
new file mode 100644
index 00000000000..b1b740cd1ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/qualifiedExpressions.fir.kt
@@ -0,0 +1,8 @@
+// FILE: a.kt
+package example.ns
+val y: Any? = 2
+
+// FILE: b.kt
+package example
+
+val x: Int = if (example.ns.y is Int) example.ns.y else 2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/unaryMinusDepOnExpType.fir.kt b/compiler/testData/diagnostics/tests/evaluate/unaryMinusDepOnExpType.fir.kt
new file mode 100644
index 00000000000..361eff19dee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/unaryMinusDepOnExpType.fir.kt
@@ -0,0 +1,36 @@
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(-1)
+    <!INAPPLICABLE_CANDIDATE!>fooInt<!>(-1111111111111111111)
+    fooInt(-1.toInt())
+    fooInt(-1.toByte())
+    <!INAPPLICABLE_CANDIDATE!>fooInt<!>(-1.toLong())
+    fooInt(-1.toShort())
+
+    fooByte(-1)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(-1111111111111111111)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(-1.toInt())
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(-1.toByte())
+    fooByte((-1).toByte())
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(-1.toLong())
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(-1.toShort())
+
+    fooLong(-1)
+    fooLong(-1111111111111111111)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(-1.toInt())
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(-1.toByte())
+    fooLong(-1.toLong())
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(-1.toShort())
+
+    fooShort(-1)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(-1111111111111111111)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(-1.toInt())
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(-1.toByte())
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(-1.toLong())
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(-1.toShort())
+    fooShort((-1).toShort())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/unaryMinusIndepWoExpType.fir.kt b/compiler/testData/diagnostics/tests/evaluate/unaryMinusIndepWoExpType.fir.kt
new file mode 100644
index 00000000000..4e2b30d44b0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/unaryMinusIndepWoExpType.fir.kt
@@ -0,0 +1,41 @@
+val p1 = -1
+val p2 = -1.toLong()
+val p3 = (-1).toByte()
+val p4 = -1.toInt()
+val p5 = (-1).toShort()
+val p6 = -1111111111111111111
+
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(p1)
+    <!INAPPLICABLE_CANDIDATE!>fooInt<!>(p2)
+    <!INAPPLICABLE_CANDIDATE!>fooInt<!>(p3)
+    fooInt(p4)
+    <!INAPPLICABLE_CANDIDATE!>fooInt<!>(p5)
+    fooInt(p6)
+
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p1)
+    fooLong(p2)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p3)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p4)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p5)
+    <!INAPPLICABLE_CANDIDATE!>fooLong<!>(p6)
+
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p1)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p2)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p3)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p4)
+    fooShort(p5)
+    <!INAPPLICABLE_CANDIDATE!>fooShort<!>(p6)
+
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p1)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p2)
+    fooByte(p3)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p4)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p5)
+    <!INAPPLICABLE_CANDIDATE!>fooByte<!>(p6)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/unaryMinusIndependentExpType.fir.kt b/compiler/testData/diagnostics/tests/evaluate/unaryMinusIndependentExpType.fir.kt
new file mode 100644
index 00000000000..29a08c66433
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/unaryMinusIndependentExpType.fir.kt
@@ -0,0 +1,29 @@
+val p1: Int = -1
+val p2: Long = -1
+val p3: Byte = -1
+val p4: Short = -1
+
+val lp1: Int = -1111111111111111111
+val lp2: Long = -1111111111111111111
+val lp3: Byte = -1111111111111111111
+val lp4: Short = -1111111111111111111
+
+val l1: Long = -1.toLong()
+val l2: Byte = -1.toLong()
+val l3: Int = -1.toLong()
+val l4: Short = -1.toLong()
+
+val b1: Byte = -1.toByte()
+val b2: Int = -1.toByte()
+val b3: Long = -1.toByte()
+val b4: Short = -1.toByte()
+
+val i1: Byte = -1.toInt()
+val i2: Int = -1.toInt()
+val i3: Long = -1.toInt()
+val i4: Short = -1.toInt()
+
+val s1: Byte = -1.toShort()
+val s2: Int = -1.toShort()
+val s3: Long = -1.toShort()
+val s4: Short = -1.toShort()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/evaluate/wrongLongSuffix.fir.kt b/compiler/testData/diagnostics/tests/evaluate/wrongLongSuffix.fir.kt
new file mode 100644
index 00000000000..1284617c8df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/evaluate/wrongLongSuffix.fir.kt
@@ -0,0 +1,10 @@
+val a1: Int = 1l
+val a2: Int = 0x1l
+val a3: Int = 0X1l
+val a4: Int = 0b1l
+val a5: Int = 0B1l
+val a6: Long = 1l
+val a7: Long = 0x1l
+val a8: Long = 0X1l
+val a9: Long = 0b1l
+val a10: Long = 0B1l
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/delegate.fir.kt b/compiler/testData/diagnostics/tests/exposed/delegate.fir.kt
new file mode 100644
index 00000000000..e2e02550d2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/delegate.fir.kt
@@ -0,0 +1,6 @@
+interface My
+
+internal class Your: My
+
+// Code is valid, despite of delegate is internal
+class His: My by Your()
diff --git a/compiler/testData/diagnostics/tests/exposed/exceptionOnFakeInvisible.fir.kt b/compiler/testData/diagnostics/tests/exposed/exceptionOnFakeInvisible.fir.kt
new file mode 100644
index 00000000000..bba58b45e5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/exceptionOnFakeInvisible.fir.kt
@@ -0,0 +1,12 @@
+// KT-14469: SOE during effective visibility evaluation
+
+abstract class Base(private val v: String)
+
+fun bar(arg: String) = arg
+
+class Derived : Base("123") {
+
+    private inline fun foo() {
+        bar(<!INAPPLICABLE_CANDIDATE!>v<!>)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/exposed/functional.fir.kt b/compiler/testData/diagnostics/tests/exposed/functional.fir.kt
new file mode 100644
index 00000000000..6b49dbee9bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/functional.fir.kt
@@ -0,0 +1,12 @@
+internal class My
+
+class Your
+
+// Both arguments should be exposed
+fun foo(my: My, f: (My) -> Unit) = f(my)
+
+// Ok
+fun bar(your: Your, f: (Your) -> Unit) = f(your)
+
+// Exposed, returns My
+fun gav(f: () -> My) = f()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/implements.fir.kt b/compiler/testData/diagnostics/tests/exposed/implements.fir.kt
new file mode 100644
index 00000000000..8e26914c1fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/implements.fir.kt
@@ -0,0 +1,4 @@
+private interface My
+
+// valid, it's allowed to implement worse-visible interface
+class Your: My
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/inaccessibleType.fir.kt b/compiler/testData/diagnostics/tests/exposed/inaccessibleType.fir.kt
new file mode 100644
index 00000000000..9a2045952a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/inaccessibleType.fir.kt
@@ -0,0 +1,89 @@
+// !DIAGNOSTICS: -USELESS_CAST -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+// FILE: j/Base.java
+package j;
+public interface Base {
+    void foo();
+}
+
+// FILE: j/Impl.java
+package j;
+
+/* package */ abstract class Impl implements Base {
+    public void foo() {}
+}
+
+// FILE: j/Derived1.java
+package j;
+
+public class Derived1 extends Impl {}
+
+// FILE: j/Derived2.java
+package j;
+
+public class Derived2 extends Impl {}
+
+// FILE: k/Client.kt
+package k
+
+import j.*
+
+val d1 = Derived1()
+val d2 = Derived2()
+
+fun <T> select(x1: T, x2: T) = x1
+fun <T> selectn(vararg xx: T) = xx[0]
+fun <T : Base> foo(x: T) = x.foo()
+fun <T> listOf2(x1: T, x2: T): List<T> = null!!
+fun <T> arrayOf2(x1: T, x2: T): Array<T> = null!!
+
+fun test() {
+    val test1: Base = if (true) d1 else d2
+
+    val test2 = if (true) d1 else d2
+
+    val test3 = when {
+        true -> d1
+        else -> d2
+    }
+
+    val test4: Base = when {
+        true -> d1
+        else -> d2
+    }
+
+    val test5 = select(d1, d2)
+
+    val test6 = select<Base>(d1, d2)
+
+    val test7 = select(d1 as Base, d2)
+
+    val test8 = selectn(d1, d2)
+
+    val test9 = selectn<Base>(d1, d2)
+
+    val test10 = listOf2(d1, d2)
+
+    val test11: List<Base> = listOf2(d1, d2)
+    // NB Inferred type is List<Impl> because List is covariant.
+
+    val test12 = listOf2<Base>(d1, d2)
+
+    val test13 = arrayOf2(d1, d2)
+
+    val test14: Array<Base> = arrayOf2(d1, d2)
+    // NB Inferred type is Array<Base> because Array is invariant.
+
+    val test15 = arrayOf2<Base>(d1, d2)
+
+    for (test16 in listOf2(d1, d2)) {}
+}
+
+fun testOkInJava() {
+    // The following is Ok in Java, but is an error in Kotlin.
+    // TODO do not generate unneeded CHECKCASTs.
+    // TODO do not report INACCESSIBLE_TYPE for corresponding cases.
+    select(d1, d2)
+    foo(select(d1, d2))
+}
diff --git a/compiler/testData/diagnostics/tests/exposed/internal.fir.kt b/compiler/testData/diagnostics/tests/exposed/internal.fir.kt
new file mode 100644
index 00000000000..e098b640ce4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/internal.fir.kt
@@ -0,0 +1,25 @@
+internal open class My
+
+// valid, internal from internal
+internal open class Your: My() {
+    // valid, effectively internal
+    fun foo() = My()
+}
+
+// error, public from internal
+open class His: Your() {
+    protected open class Nested
+    // error, public from internal
+    val x = My()
+    // valid, private from internal
+    private fun bar() = My()
+    // valid, internal from internal
+    internal var y: My? = null
+    // error, protected from internal
+    protected fun baz() = Your()
+}
+
+internal class Their: His() {
+    // error, effectively internal from protected
+    class InnerDerived: His.Nested()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/internalAndProtected.fir.kt b/compiler/testData/diagnostics/tests/exposed/internalAndProtected.fir.kt
new file mode 100644
index 00000000000..69c94fee1d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/internalAndProtected.fir.kt
@@ -0,0 +1,10 @@
+public open class A {
+    protected open class B
+}
+
+public open class C : A() {
+    protected open class D {
+        // internal & protected(in C) <= protected(in A): Ok
+        internal open class E : A.B() 
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/exposed/internalFromLocal.fir.kt b/compiler/testData/diagnostics/tests/exposed/internalFromLocal.fir.kt
new file mode 100644
index 00000000000..b1481169882
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/internalFromLocal.fir.kt
@@ -0,0 +1,10 @@
+interface Your
+
+class My {
+    internal val x = object : Your {}
+
+    internal fun foo() = <!UNRESOLVED_REFERENCE!>{
+        class Local
+        Local()
+    }()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/local.fir.kt b/compiler/testData/diagnostics/tests/exposed/local.fir.kt
new file mode 100644
index 00000000000..7d6e06dbfea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/local.fir.kt
@@ -0,0 +1,18 @@
+// invalid, depends on local class
+fun foo() = run {
+    class A
+    A()
+}
+
+// invalid, depends on local class
+fun gav() = {
+    class B
+    B()
+}
+
+abstract class My
+
+// valid, object literal here is effectively My
+fun bar() = run {
+    object: My() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/localFromInternal.fir.kt b/compiler/testData/diagnostics/tests/exposed/localFromInternal.fir.kt
new file mode 100644
index 00000000000..89521bdd0dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/localFromInternal.fir.kt
@@ -0,0 +1,7 @@
+class My {
+    internal open class ThreadLocal
+    // Private from local: ???
+    private val values = 
+            // Local from internal: Ok
+            object: ThreadLocal() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/localFromPrivate.fir.kt b/compiler/testData/diagnostics/tests/exposed/localFromPrivate.fir.kt
new file mode 100644
index 00000000000..9156292343b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/localFromPrivate.fir.kt
@@ -0,0 +1,15 @@
+class A {
+    private open class B
+    fun f() {
+        // Local from private: Ok
+        class C : B()
+    }
+}
+
+private open class D
+
+fun f(): Int {
+    // Local from private: Ok
+    val x = object : D() { }
+    return x.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/localInFunReturnType.fir.kt b/compiler/testData/diagnostics/tests/exposed/localInFunReturnType.fir.kt
new file mode 100644
index 00000000000..c37928f2317
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/localInFunReturnType.fir.kt
@@ -0,0 +1,60 @@
+class My<T>(val value: T)
+
+open class Base
+
+fun invalid1() = run {
+    class Local
+    My(Local())
+}
+
+fun invalid2() = My(object {})
+
+fun invalid3() = My(object : Base() {})
+
+fun invalid4() = run {
+    class Local
+    My(My(Local()))
+}
+
+fun invalid5() = run {
+    fun invalid5a() = run {
+        class Local
+        Local()
+    }
+    My(invalid5a())
+}
+
+// Valid: effectively Any
+fun valid1() = object {}
+
+// Valid: effectively Base
+fun valid2() = object : Base() {}
+
+// Valid: explicit type argument
+fun valid3() = My<Base>(object : Base() {})
+
+// Valid: explicit type specified
+fun valid4() : My<Base> = My(object : Base() {})
+
+// Valid: local class denotable in local scope
+fun valid5() = run {
+    class Local
+    fun valid5a() = My(Local())
+    My<Any>(valid5a())
+}
+
+// Valid: local class denotable in local scope
+fun valid6() = run {
+    class Local
+    fun valid6a() = run {
+        fun valid6b() = My(Local())
+        valid6b()
+    }
+    My<Any>(valid6a())
+}
+
+// Valid: effectively My<Any>
+fun valid7() = run {
+    class Local
+    My<My<*>>(My(Local()))
+}
diff --git a/compiler/testData/diagnostics/tests/exposed/localInMemberType.fir.kt b/compiler/testData/diagnostics/tests/exposed/localInMemberType.fir.kt
new file mode 100644
index 00000000000..8bc8f6a0ca0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/localInMemberType.fir.kt
@@ -0,0 +1,21 @@
+class Something {
+    public val publicVal1 = object { override fun toString() = "!" }
+    protected val protectedVal1 = object { override fun toString() = "!" }
+    internal val internalVal1 = object { override fun toString() = "!" }
+    private val privateVal1 = object { override fun toString() = "!" }
+
+    public val publicVal2 = run { class A; A() }
+    protected val protectedVal2 = run { class A; A() }
+    internal val internalVal2 = run { class A; A() }
+    private val privateVal2 = run { class A; A() }
+
+    public fun publicFun1() = object { override fun toString() = "!" }
+    protected fun protectedFun1() = object { override fun toString() = "!" }
+    internal fun internalFun1() = object { override fun toString() = "!" }
+    private fun privateFun1() = object { override fun toString() = "!" }
+
+    public fun publicFun2() = run { class A; A() }
+    protected fun protectedFun2() = run { class A; A() }
+    internal fun internalFun2() = run { class A; A() }
+    private fun privateFun2() = run { class A; A() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/localInPropertyType.fir.kt b/compiler/testData/diagnostics/tests/exposed/localInPropertyType.fir.kt
new file mode 100644
index 00000000000..ca2fbd3d9fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/localInPropertyType.fir.kt
@@ -0,0 +1,60 @@
+class My<T>(val value: T)
+
+open class Base
+
+val invalid1 = run {
+    class Local
+    My(Local())
+}
+
+val invalid2 = My(object {})
+
+val invalid3 = My(object : Base() {})
+
+val invalid4 = run {
+    class Local
+    My(My(Local()))
+}
+
+val invalid5 = run {
+    fun invalid5a() = run {
+        class Local
+        Local()
+    }
+    My(invalid5a())
+}
+
+// Valid: effectively Any
+val valid1 = object {}
+
+// Valid: effectively Base
+val valid2 = object : Base() {}
+
+// Valid: explicit type argument
+val valid3 = My<Base>(object : Base() {})
+
+// Valid: explicit type specified
+val valid4 : My<Base> = My(object : Base() {})
+
+// Valid: local class denotable in local scope
+val valid5 = run {
+    class Local
+    fun valid5a() = My(Local())
+    My<Any>(valid5a())
+}
+
+// Valid: local class denotable in local scope
+val valid6 = run {
+    class Local
+    fun valid6a() = run {
+        fun valid6b() = My(Local())
+        valid6b()
+    }
+    My<Any>(valid6a())
+}
+
+// Valid: effectively My<Any>
+val valid7 = run {
+    class Local
+    My<My<*>>(My(Local()))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/nested.fir.kt b/compiler/testData/diagnostics/tests/exposed/nested.fir.kt
new file mode 100644
index 00000000000..57e35086ad8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/nested.fir.kt
@@ -0,0 +1,6 @@
+internal open class My
+
+internal class Outer {
+    // Ok, effectively internal from internal
+    class Your: My()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/object.fir.kt b/compiler/testData/diagnostics/tests/exposed/object.fir.kt
new file mode 100644
index 00000000000..ec72d2bbd68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/object.fir.kt
@@ -0,0 +1,30 @@
+// From KT-10753
+object My : Inter() {
+    fun foo(arg: Inter): Inter = arg
+    val x: Inter? = null
+}
+
+internal open class Inter
+
+// From KT-10799
+open class Test {
+    protected class Protected
+
+    fun foo(x: Protected) = x
+
+    interface NestedInterface {
+        fun create(x: Protected)
+    }
+
+    class NestedClass {
+        fun create(x: Protected) = x
+    }
+
+    object NestedObject {
+        fun create(x: Protected) = x
+    }
+
+    companion object {
+        fun create(x: Protected) = x
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/exposed/packagePrivate.fir.kt b/compiler/testData/diagnostics/tests/exposed/packagePrivate.fir.kt
new file mode 100644
index 00000000000..f99a0622b36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/packagePrivate.fir.kt
@@ -0,0 +1,35 @@
+// JAVAC_EXPECTED_FILE
+// FILE: test/My.java
+
+package test;
+
+class Internal {}
+
+public class My {
+    static public Internal foo() { return new Internal(); }
+}
+
+// FILE: test/His.kt
+
+package test
+
+class His {
+    // Ok: private vs package-private
+    private fun private() = My.foo()
+    // Ok: internal vs package-private in same package
+    internal fun internal() = My.foo()
+    // Error: protected vs package-private
+    protected fun protected() = My.foo()
+    // Error: public vs package-private
+    fun public() = My.foo()
+}
+
+// FILE: other/Your.kt
+
+package other
+
+import test.My
+
+class Your {
+    internal fun bar() = My.foo()
+}
diff --git a/compiler/testData/diagnostics/tests/exposed/privateFromLocal.fir.kt b/compiler/testData/diagnostics/tests/exposed/privateFromLocal.fir.kt
new file mode 100644
index 00000000000..418bbfef433
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/privateFromLocal.fir.kt
@@ -0,0 +1,12 @@
+interface Your
+
+class My {
+    // private from local: ???
+    private val x = object : Your {}
+
+    // private from local: ???
+    private fun foo() = <!UNRESOLVED_REFERENCE!>{
+        class Local
+        Local()
+    }()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/privatePropertyInPrivateConstructor.fir.kt b/compiler/testData/diagnostics/tests/exposed/privatePropertyInPrivateConstructor.fir.kt
new file mode 100644
index 00000000000..db0bb7a35bd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/privatePropertyInPrivateConstructor.fir.kt
@@ -0,0 +1,3 @@
+private enum class Foo { A, B }
+
+class Bar private constructor(private val foo: Foo)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/propertyInConstructorOfPrivateClass.fir.kt b/compiler/testData/diagnostics/tests/exposed/propertyInConstructorOfPrivateClass.fir.kt
new file mode 100644
index 00000000000..d2b672f3f0e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/propertyInConstructorOfPrivateClass.fir.kt
@@ -0,0 +1,3 @@
+private enum class Foo { A, B }
+
+private class Bar(val foo: Foo)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/propertyInPrivateConstructor.fir.kt b/compiler/testData/diagnostics/tests/exposed/propertyInPrivateConstructor.fir.kt
new file mode 100644
index 00000000000..59754a5f667
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/propertyInPrivateConstructor.fir.kt
@@ -0,0 +1,3 @@
+private enum class Foo { A, B }
+
+class Bar private constructor(val foo: Foo)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/propertyInSimpleConstructor.fir.kt b/compiler/testData/diagnostics/tests/exposed/propertyInSimpleConstructor.fir.kt
new file mode 100644
index 00000000000..b93fcfa3b98
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/propertyInSimpleConstructor.fir.kt
@@ -0,0 +1,3 @@
+private enum class Foo { A, B }
+
+class Bar(val foo: Foo)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/protected.fir.kt b/compiler/testData/diagnostics/tests/exposed/protected.fir.kt
new file mode 100644
index 00000000000..88919501eba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/protected.fir.kt
@@ -0,0 +1,20 @@
+open class A {
+    // protected relative to A
+    protected open class B { 
+        fun foo() {}
+    }
+    public open class C {
+        // protected relative to C, must be an error
+        protected open class D : B()
+    }
+}
+
+class E : A.C() {
+    // F has invisible grandparent class B (E does not inherit from A)
+    class F : A.C.D() {
+        init {
+            // Invoke function from invisible grandparent
+            foo() 
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/protectedInProtected.fir.kt b/compiler/testData/diagnostics/tests/exposed/protectedInProtected.fir.kt
new file mode 100644
index 00000000000..9c55dbc067d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/protectedInProtected.fir.kt
@@ -0,0 +1,12 @@
+// See KT-9540 
+
+// all protected should have lower bound that is more permissive than private
+// protected and internal should have lower bound that is more permissive than private
+open class A {
+    private interface B
+    protected open class C {
+        protected interface D : B
+        internal interface E : B, D
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/exposed/protectedJava.fir.kt b/compiler/testData/diagnostics/tests/exposed/protectedJava.fir.kt
new file mode 100644
index 00000000000..29096cf0d16
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/protectedJava.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Outer.java
+
+public abstract class Outer {
+    protected static class My {}
+    protected static class Your extends My {}
+    abstract protected Your foo(My my);
+}
+
+// FILE: OuterDerived.kt
+
+class OuterDerived: Outer() {
+    // valid, My has better visibility
+    protected class His: Outer.My()
+    // valid, My and Your have better visibility
+    override fun foo(my: Outer.My) = Outer.Your()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/protectedSameWay.fir.kt b/compiler/testData/diagnostics/tests/exposed/protectedSameWay.fir.kt
new file mode 100644
index 00000000000..9925008e88c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/protectedSameWay.fir.kt
@@ -0,0 +1,13 @@
+abstract class Outer {
+    protected open class My
+    // Both valid: same way protected
+    protected class Your: My()
+    abstract protected fun foo(my: My): Your
+}
+
+class OuterDerived: Outer() {
+    // valid, My has better visibility
+    protected class His: Outer.My()
+    // valid, My and Your have better visibility
+    override fun foo(my: Outer.My) = Outer.Your()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/exposed/simple.fir.kt b/compiler/testData/diagnostics/tests/exposed/simple.fir.kt
new file mode 100644
index 00000000000..72ec119da23
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/simple.fir.kt
@@ -0,0 +1,23 @@
+private interface My
+
+private open class Base
+
+public interface Your: My {
+    fun <T: Base> foo(): T
+}
+
+public class Derived<T: My>(val x: My): Base() {
+
+    constructor(xx: My?, x: My): this(xx ?: x)
+
+    val y: Base? = null
+
+    val My.z: Int
+        get() = 42
+
+    fun foo(m: My): My = m
+
+    fun My.bar(): My = this
+}
+
+
diff --git a/compiler/testData/diagnostics/tests/exposed/typeArgs.fir.kt b/compiler/testData/diagnostics/tests/exposed/typeArgs.fir.kt
new file mode 100644
index 00000000000..ff682fb7c35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/exposed/typeArgs.fir.kt
@@ -0,0 +1,17 @@
+internal open class My
+
+abstract class Your {
+    // invalid, List<My> is effectively internal
+    abstract fun give(): List<My>
+}
+
+// invalid, List<My> is effectively internal
+interface His: List<My>
+
+// invalid, My is internal
+interface Generic<E: My>
+
+interface Our {
+    // invalid, Generic<My> is effectively internal
+    fun foo(): Generic<*>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/ExtensionFunctions.fir.kt b/compiler/testData/diagnostics/tests/extensions/ExtensionFunctions.fir.kt
new file mode 100644
index 00000000000..efd4ec1e4d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/ExtensionFunctions.fir.kt
@@ -0,0 +1,76 @@
+// !WITH_NEW_INFERENCE
+// FILE: b.kt
+package outer
+
+fun Int?.optint() : Unit {}
+val Int?.optval : Unit get() = Unit
+
+fun <T: Any, E> T.foo(x : E, y : A) : T   {
+  y.plus(1)
+  y plus 1
+  y + 1.0
+
+  this?.minus<T>(this)
+
+  return this
+}
+
+class A
+
+infix operator fun A.plus(a : Any) {
+
+  1.foo()
+  true.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+
+  1
+}
+
+operator fun A.plus(a : Int) {
+  1
+}
+
+operator fun <T> T.minus(t : T) : Int = 1
+
+fun test() {
+  val y = 1.abs
+}
+val Int.abs : Int
+  get() = if (this > 0) this else -this;
+
+val <T> T.foo : T
+
+fun Int.foo() = this
+
+// FILE: b.kt
+package null_safety
+
+import outer.*
+
+        fun parse(cmd: String): Command? { return null  }
+        class Command() {
+        //  fun equals(other : Any?) : Boolean
+          val foo : Int = 0
+        }
+
+        fun Any.equals(other : Any?) : Boolean = true
+        fun Any?.equals1(other : Any?) : Boolean = true
+        fun Any.equals2(other : Any?) : Boolean = true
+
+        fun main() {
+
+            System.out.print(1)
+
+            val command = parse("")
+
+            command.foo
+
+            command.<!INAPPLICABLE_CANDIDATE!>equals<!>(null)
+            command?.equals(null)
+            command.equals1(null)
+            command?.equals1(null)
+
+            val c = Command()
+            c?.equals2(null)
+
+            if (command == null) 1
+        }
diff --git a/compiler/testData/diagnostics/tests/extensions/ExtensionsCalledOnSuper.fir.kt b/compiler/testData/diagnostics/tests/extensions/ExtensionsCalledOnSuper.fir.kt
new file mode 100644
index 00000000000..165fbc3e271
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/ExtensionsCalledOnSuper.fir.kt
@@ -0,0 +1,22 @@
+interface T {
+    fun foo() {}
+    fun buzz() {}
+    fun buzz1(i : Int) {}
+}
+
+fun T.bar() {}
+
+fun T.buzz() {}
+fun T.buzz1() {}
+
+class C : T {
+    fun test() {
+        fun T.buzz() {}
+        fun T.buzz1() {}
+        super.foo() // OK
+        super.bar() // Error
+        super.buzz() // OK, resolved to a member
+        super.buzz1() // Resolved to an extension
+        super.<!INAPPLICABLE_CANDIDATE!>buzz1<!>("") // Resolved to a member
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/GenericIterator.fir.kt b/compiler/testData/diagnostics/tests/extensions/GenericIterator.fir.kt
new file mode 100644
index 00000000000..480c208080f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/GenericIterator.fir.kt
@@ -0,0 +1,36 @@
+import java.util.Enumeration
+
+fun <T> java.util.Enumeration<T>.iterator() = object: Iterator<T> {
+  override fun hasNext(): Boolean = hasMoreElements()
+
+  override fun next() = nextElement()
+}
+
+interface MyIterator<T> {
+
+  operator fun hasNext() : Boolean
+
+  operator fun next() : T
+}
+
+operator fun <T : Any> T?.iterator() = object : MyIterator<T> {
+    var hasNext = this@iterator != null
+      private set
+    override fun hasNext() = hasNext
+
+    override fun next() : T {
+        if (hasNext) {
+            hasNext = false
+            return this@iterator!!
+        }
+        throw java.util.<!UNRESOLVED_REFERENCE!>NoSuchElementException<!>()
+    }
+}
+
+fun main() {
+  val i : Int? = 1
+  for (x in i) {
+    System.out.println(x)
+  }
+}
+
diff --git a/compiler/testData/diagnostics/tests/extensions/GenericIterator2.fir.kt b/compiler/testData/diagnostics/tests/extensions/GenericIterator2.fir.kt
new file mode 100644
index 00000000000..32790a9b6f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/GenericIterator2.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+import java.util.Enumeration
+
+operator fun <T> java.util.Enumeration<T>.iterator() = object : Iterator<T> {
+  public override fun hasNext(): Boolean = hasMoreElements()
+
+  public override fun next() = nextElement()
+}
+
+fun a(e : java.util.Enumeration<Int>) {
+    for (i in e) {
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(i)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/extensions/classObject.fir.kt b/compiler/testData/diagnostics/tests/extensions/classObject.fir.kt
new file mode 100644
index 00000000000..59906776f9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/classObject.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+interface Tr
+
+class A { companion object }
+class B { companion object : Tr }
+
+fun Any.f1() {}
+fun Any?.f2() {}
+fun Tr.f3() {}
+fun Tr?.f4() {}
+fun A.f5() {}
+
+fun test() {
+    A.f1()
+    A.f2()
+    B.f3()
+    B.f4()
+    A.<!INAPPLICABLE_CANDIDATE!>f5<!>()
+    B.<!INAPPLICABLE_CANDIDATE!>f5<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/extensionMemberInClassObject.fir.kt b/compiler/testData/diagnostics/tests/extensions/extensionMemberInClassObject.fir.kt
new file mode 100644
index 00000000000..5b5862e9dae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/extensionMemberInClassObject.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface JPAEntityClass<D> {
+    fun <T> T.findByName(s: String): D {null!!}
+}
+
+class Foo {
+    companion object : JPAEntityClass<Foo>
+}
+
+fun main() {
+    with("", {
+        Foo.<!UNRESOLVED_REFERENCE!>findByName<!>("")
+    })
+    with(Foo) {
+        findByName("")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/extensions/extensionPropertyVsParameter.fir.kt b/compiler/testData/diagnostics/tests/extensions/extensionPropertyVsParameter.fir.kt
new file mode 100644
index 00000000000..4ae6532be52
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/extensionPropertyVsParameter.fir.kt
@@ -0,0 +1,8 @@
+val Int.foo: Int
+    get() = this
+
+
+fun test(foo: Int) {
+    test(4.foo)
+    test(foo)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/kt1875.fir.kt b/compiler/testData/diagnostics/tests/extensions/kt1875.fir.kt
new file mode 100644
index 00000000000..0ea80d168cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/kt1875.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+//KT-1875 Safe call should be binded with receiver or this object (but not with both by default)
+
+package kt1875
+
+fun foo(a : Int?, b : Int.(Int)->Int) = a?.<!UNRESOLVED_REFERENCE!>b<!>(1) //unnecessary safe call warning
+
+interface T {
+    val f : ((i: Int) -> Unit)?
+}
+
+fun test(t: T) {
+    t.<!INAPPLICABLE_CANDIDATE!>f<!>(1) //unsafe call error
+    t.f?.invoke(1)
+}
+
+fun test1(t: T?) {
+    t.<!UNRESOLVED_REFERENCE!>f<!>(1) // todo resolve f as value and report UNSAFE_CALL
+    t?.f(1)
+    t.<!INAPPLICABLE_CANDIDATE!>f<!>?.<!UNRESOLVED_REFERENCE!>invoke<!>(1)
+    t?.f?.invoke(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/kt2317.fir.kt b/compiler/testData/diagnostics/tests/extensions/kt2317.fir.kt
new file mode 100644
index 00000000000..6bd8ceac485
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/kt2317.fir.kt
@@ -0,0 +1,15 @@
+//KT-2317 Wrong UNNECESSARY_SAFE_CALL
+
+package kt2317
+
+fun Any?.baz() = 1
+
+fun foo(l: Long?) = l?.baz()
+
+
+fun Any?.bar(): Unit { }
+
+fun quux(x: Int?): Unit {
+	x?.baz()
+	x?.bar()
+}
diff --git a/compiler/testData/diagnostics/tests/extensions/kt3470.fir.kt b/compiler/testData/diagnostics/tests/extensions/kt3470.fir.kt
new file mode 100644
index 00000000000..60704abda29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/kt3470.fir.kt
@@ -0,0 +1,7 @@
+class A {
+    companion object {
+        fun foo() = toString()
+    }
+}
+
+val a = A.toString()
diff --git a/compiler/testData/diagnostics/tests/extensions/kt3563.fir.kt b/compiler/testData/diagnostics/tests/extensions/kt3563.fir.kt
new file mode 100644
index 00000000000..802dc2207e7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/kt3563.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// KT-3563 Compiler requiring java.io.File, and it's unclear why
+
+package bar
+
+import java.io.File
+
+class Customer(name1: String)
+
+fun foo(f: File, c: Customer) {
+    f.name1
+
+    c.<!INAPPLICABLE_CANDIDATE!>name1<!> // name1 should be unresolved here
+}
+
+val File.name1: String
+    get() = getName()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/kt819ExtensionProperties.fir.kt b/compiler/testData/diagnostics/tests/extensions/kt819ExtensionProperties.fir.kt
new file mode 100644
index 00000000000..16cf1f80eae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/kt819ExtensionProperties.fir.kt
@@ -0,0 +1,37 @@
+//KT-819 Redeclaration error for extension properties with the same name and different receivers
+// FULL_JDK
+
+import java.io.*
+
+val InputStream.buffered : BufferedInputStream
+    get() = if(this is BufferedInputStream) this else BufferedInputStream(this)
+
+val Reader.buffered : BufferedReader
+    get() = if(this is BufferedReader) this else BufferedReader(this)
+
+
+//more tests
+open class A() {
+    open fun String.foo() {}
+    open fun Int.foo() {}
+
+    open val String.foo: Int
+        get() = 0
+    open val Int.foo: Int
+        get() = 1
+}
+
+class B() : A() {
+    override fun String.foo() {}
+    override fun Int.foo() {}
+
+    override val String.foo: Int
+        get() = 0
+    override val Int.foo: Int
+        get() = 0
+
+    fun use(s: String) {
+        s.foo
+        s.foo()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/extensions/noClassObjectsInJava.fir.kt b/compiler/testData/diagnostics/tests/extensions/noClassObjectsInJava.fir.kt
new file mode 100644
index 00000000000..e95008cb979
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/noClassObjectsInJava.fir.kt
@@ -0,0 +1,11 @@
+// FILE: A.java
+public class A {
+    public static void foo() {}
+    public static class Nested {}
+}
+
+// FILE: B.kt
+fun Any?.bar() = 42
+
+fun f1() = A.bar()
+fun f2() = A.Nested.bar()
diff --git a/compiler/testData/diagnostics/tests/extensions/object.fir.kt b/compiler/testData/diagnostics/tests/extensions/object.fir.kt
new file mode 100644
index 00000000000..359316e1b95
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/object.fir.kt
@@ -0,0 +1,6 @@
+object O
+
+fun Any.foo() = 42
+val Any?.bar: Int get() = 239
+
+val x = O.foo() + O.bar
diff --git a/compiler/testData/diagnostics/tests/extensions/throwOutCandidatesByReceiver.fir.kt b/compiler/testData/diagnostics/tests/extensions/throwOutCandidatesByReceiver.fir.kt
new file mode 100644
index 00000000000..101fc69277d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/throwOutCandidatesByReceiver.fir.kt
@@ -0,0 +1,56 @@
+// !WITH_NEW_INFERENCE
+package bar
+
+
+// should be thrown away
+
+fun <R> List<R>.a() {}
+
+fun test1(i: Int?) {
+    1.<!INAPPLICABLE_CANDIDATE!>a<!>()
+    i.<!INAPPLICABLE_CANDIDATE!>a<!>()
+}
+
+fun <R> test2(c: Collection<R>) {
+    c.<!INAPPLICABLE_CANDIDATE!>a<!>()
+}
+
+fun Int.foo() {}
+
+fun test3(s: String?) {
+    "".<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    s.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    "".<!INAPPLICABLE_CANDIDATE!>foo<!>(1)
+    s.<!INAPPLICABLE_CANDIDATE!>foo<!>("a")
+}
+
+interface A
+fun <T: A> T.c() {}
+
+fun test4() {
+    1.<!INAPPLICABLE_CANDIDATE!>c<!>()
+}
+
+
+// should be an error on receiver, shouldn't be thrown away
+
+fun test5() {
+    1.<!UNRESOLVED_REFERENCE!>(fun String.()=1)()<!>
+}
+
+fun <R: Any> R?.sure() : R = this!!
+
+fun <T> test6(l: List<T>?) {
+    l.<!INAPPLICABLE_CANDIDATE!>sure<!><T>()
+}
+
+
+fun List<String>.b() {}
+
+fun test7(l: List<String?>) {
+    l.<!INAPPLICABLE_CANDIDATE!>b<!>()
+}
+
+fun test8(l: List<Any>?) {
+    l.<!INAPPLICABLE_CANDIDATE!>b<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/throwOutCandidatesByReceiver2.fir.kt b/compiler/testData/diagnostics/tests/extensions/throwOutCandidatesByReceiver2.fir.kt
new file mode 100644
index 00000000000..634d38bae98
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/throwOutCandidatesByReceiver2.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+package a
+
+class A {}
+
+fun test(a1: A, a2: A) {
+    val range = "island".."isle"
+
+    a1<!INAPPLICABLE_CANDIDATE!>..<!>a2
+}
+
+
+public operator fun <T: Comparable<T>> T.rangeTo(that: T): ClosedRange<T> {
+    throw UnsupportedOperationException()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/extensions/variableInvoke.fir.kt b/compiler/testData/diagnostics/tests/extensions/variableInvoke.fir.kt
new file mode 100644
index 00000000000..831c40af196
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/extensions/variableInvoke.fir.kt
@@ -0,0 +1,11 @@
+class A(foo: Int.() -> Unit) {
+    init {
+        4.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+}
+
+fun test(foo: Int.(String) -> Unit) {
+    4.<!UNRESOLVED_REFERENCE!>foo<!>("")
+    4.<!UNRESOLVED_REFERENCE!>foo<!>(p1 = "")
+    4.<!UNRESOLVED_REFERENCE!>foo<!>(p2 = "")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/fileDependencyRecursion.fir.kt b/compiler/testData/diagnostics/tests/fileDependencyRecursion.fir.kt
new file mode 100644
index 00000000000..d4302a476a5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/fileDependencyRecursion.fir.kt
@@ -0,0 +1,15 @@
+// FILE: fileDependencyRecursion.kt
+package test
+
+import testOther.some
+
+val normal: Int = 1
+val fromImported: Int = some
+
+// FILE: fileDependencyRecursionOther.kt
+package testOther
+
+import test.normal
+
+val some: Int = 1
+val fromImported: Int = normal
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/AutoLabels.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/AutoLabels.fir.kt
new file mode 100644
index 00000000000..1b2f22647d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/AutoLabels.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+
+fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> = null!!
+
+fun autolabel(l: List<Int>) = l.map (fun (i: Int): Int {
+    return@map 4
+})
+
+fun unresolvedMapLabel(l: List<Int>) = l.map (l@ fun(i: Int): Int {
+    return@map 4
+})
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/Common.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/Common.fir.kt
new file mode 100644
index 00000000000..ce39b853d92
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/Common.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+annotation class ann(val name: String)
+const val ok = "OK"
+
+class A
+
+val withoutName = fun () {}
+val extensionWithoutName = fun A.() {}
+
+fun withAnnotation() = @ann(ok) fun () {}
+val withReturn = fun (): Int { return 5}
+val withExpression = fun() = 5
+val funfun = fun() = fun() = 5
+
+val parentesized = (fun () {})
+val parentesizedWithType = checkSubtype<() -> Unit>((fun () {}))
+val withType = checkSubtype<() -> Unit>((fun () {}))
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/DifficultInferenceForParameter.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/DifficultInferenceForParameter.fir.kt
new file mode 100644
index 00000000000..1c940b44ac6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/DifficultInferenceForParameter.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+fun <T> foo(f : (T) -> T) : T = throw Exception()
+
+fun test() {
+    val a : Int = foo(fun (x) = x)
+}
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/ForbiddenNonLocalReturn.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/ForbiddenNonLocalReturn.fir.kt
new file mode 100644
index 00000000000..f7936c4f4e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/ForbiddenNonLocalReturn.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun test() {
+    fun bar() {
+        val bas = fun() {
+            return@bar
+        }
+    }
+
+    val bar = fun() {
+        return@test
+    }
+}
+
+fun foo() {
+    val bal = bag@ fun () {
+        val bar = fun() {
+            return@bag
+        }
+        return@bag
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/FunctionType.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/FunctionType.fir.kt
new file mode 100644
index 00000000000..fb97f697159
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/FunctionType.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+
+fun testReturnType(foo: String) {
+    val bar = fun () = foo
+
+    bar.checkType { _<() -> String>() }
+
+    val bas: () -> String = fun () = foo
+
+    val bag: () -> Int = fun () = foo
+}
+
+fun testParamType() {
+    val bar = fun (bal: String){}
+
+    bar.checkType { _<(String) -> Unit>() }
+
+    val bas: (String) -> Unit = fun (param: String) {}
+    val bag: (Int) -> Unit = fun (param: String) {}
+}
+
+fun testReceiverType() {
+    val bar = fun String.() {}
+
+    bar.checkType { _<String.() -> Unit>() }
+
+    val bas: String.() -> Unit = fun String.() {}
+
+    val bag: Int.() -> Unit = fun String.() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/InferenceParametersTypes.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/InferenceParametersTypes.fir.kt
new file mode 100644
index 00000000000..8a6a7e6d36b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/InferenceParametersTypes.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+fun <T> listOf(): List<T> = null!!
+
+fun test(a: (Int) -> Int) {
+    test(fun (x) = 4)
+
+    test(fun (x) = x)
+
+    test(fun (x): Int { checkSubtype<Int>(x); return 4 })
+}
+
+fun test2(a: () -> List<Int>) {
+    test2(fun () = listOf())
+}
+
+val a: (Int) -> Unit = fun(x) { checkSubtype<Int>(x) }
+
+val b: (Int) -> Unit = fun(x: String) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/MissingParameterTypes.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/MissingParameterTypes.fir.kt
new file mode 100644
index 00000000000..1ce99177991
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/MissingParameterTypes.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+
+val a = fun (x) = x
+
+val b: (Int) -> Int = fun (x) = x + 3
+
+val c: (Int, String) -> Int = fun (x) = 3
+
+val d: (Int, String) -> Int = fun (x) = 3
+
+val e: (Int, String) -> Int = fun (x: String) = 3
+
+val f: (Int) -> Int = fun (x: String) = 3
+
+fun test1(a: (Int) -> Unit) {
+    test1(fun (x) { checkSubtype<Int>(x)})
+}
+
+fun test2(a: (Int) -> Unit) {
+    <!INAPPLICABLE_CANDIDATE!>test2<!>(fun (x: String) {})
+}
+
+fun test3(a: (Int, String) -> Unit) {
+    <!INAPPLICABLE_CANDIDATE!>test3<!>(fun (x: String) {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/NameDeprecation.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/NameDeprecation.fir.kt
new file mode 100644
index 00000000000..903f86c4815
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/NameDeprecation.fir.kt
@@ -0,0 +1,9 @@
+fun foo() {
+    class A
+    fun bar() {}
+    (fun bar() {})
+    fun A.foo() {}
+    (fun A.foo() {})
+
+    run(<!INFERENCE_ERROR!>fun foo() {}<!>)
+}
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/NoOverloadError.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/NoOverloadError.fir.kt
new file mode 100644
index 00000000000..13610785b58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/NoOverloadError.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+val bar = fun() {}
+val bas = fun() {}
+
+fun gar(p: Any?) = fun() {}
+fun gas(p: Any?) = fun() {}
+
+fun outer() {
+    val bar = fun() {}
+    val bas = fun() {}
+
+    fun gar(p: Any?) = fun() {}
+    fun gas(p: Any?) = fun() {}
+
+    gar(fun() {})
+    gar(fun() {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/Parameters.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/Parameters.fir.kt
new file mode 100644
index 00000000000..1b8ccc2cd78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/Parameters.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+
+val bar = fun(p: Int = 3) {}
+val bas = fun(vararg p: Int) {}
+
+fun gar() = fun(p: Int = 3) {}
+fun gas() = fun(vararg p: Int) {}
+
+fun outer(b: Any?) {
+    val bar = fun(p: Int = 3) {}
+    val bas = fun(vararg p: Int) {}
+
+    fun gar() = fun(p: Int = 3) {}
+    fun gas() = fun(vararg p: Int) {}
+
+    outer(fun(p: Int = 3) {})
+    outer(fun(vararg p: Int) {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/ReceiverByExpectedType.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/ReceiverByExpectedType.fir.kt
new file mode 100644
index 00000000000..bcfd7229a3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/ReceiverByExpectedType.fir.kt
@@ -0,0 +1,3 @@
+// !WITH_NEW_INFERENCE
+fun foo(f: String.() -> Int) {}
+val test = foo(fun () = <!UNRESOLVED_REFERENCE!>length<!>)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/ReturnAndLabels.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/ReturnAndLabels.fir.kt
new file mode 100644
index 00000000000..519b889788a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/ReturnAndLabels.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+val label_fun = label@ fun () {
+    return@label
+}
+
+val parenthesized_label_fun = (label@ fun () {
+    return@label
+})
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/ReturnTypeCheck.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/ReturnTypeCheck.fir.kt
new file mode 100644
index 00000000000..c811328fbbb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/ReturnTypeCheck.fir.kt
@@ -0,0 +1,9 @@
+val foo = fun(a: Int): String {
+    if (a == 1) return "4"
+    when (a) {
+        5 -> return "2"
+        3 -> return null
+        2 -> return 2
+    }
+    return ""
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/ScopeCheck.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/ScopeCheck.fir.kt
new file mode 100644
index 00000000000..39fcc22ac00
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/ScopeCheck.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+interface B {
+    fun b_fun() {}
+}
+
+fun test(param: String) {
+
+    val local_val = 4
+    val bar = fun B.(fun_param: Int) {
+        param.length
+        <!UNRESOLVED_REFERENCE!>b_fun<!>()
+        val inner_bar = local_val + fun_param
+
+        <!UNRESOLVED_REFERENCE!>bar<!>
+    }
+
+    <!UNRESOLVED_REFERENCE!>inner_bar<!>
+    <!UNRESOLVED_REFERENCE!>fun_param<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/WithGenericParameters.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/WithGenericParameters.fir.kt
new file mode 100644
index 00000000000..963a47446f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/WithGenericParameters.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+
+interface A
+fun devNull(a: Any?){}
+
+val generic_fun = fun<T>(t: T): T = null!!
+val extension_generic_fun = fun<T>T.(t: T): T = null!!
+
+fun fun_with_where() = fun <T> T.(t: T): T where T: A = null!!
+
+
+fun outer() {
+    devNull(fun <T>() {})
+    devNull(fun <T> T.() {})
+    devNull(fun <T> (): T = null!!)
+    devNull(fun <T> (t: T) {})
+    devNull(fun <T> () where T:A {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/WithOuterGeneric.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/WithOuterGeneric.fir.kt
new file mode 100644
index 00000000000..ae58e457603
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/WithOuterGeneric.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun <T> parameter() = fun (t: T) = t
+fun <T> receiver() = fun T.() = this
+fun <T> returnType() = fun (): T = null!!
+
+val <T> T.fromVal: () -> T get() = fun (): T = this@fromVal
+
+fun devNull(a: Any?){}
+
+fun <O> outer() {
+    fun <T> parameter() = fun (t: T) = t
+    fun <T> receiver() = fun T.() = this
+    fun <T> returnType() = fun (): T = null!!
+
+    devNull(fun (t: O) = t)
+    devNull(fun O.() = this)
+    devNull(fun (): O = null!!)
+}
+
+class Outer<O> {
+    fun <T> parameter() = fun (t: T) = t
+    fun <T> receiver() = fun T.() = this
+    fun <T> returnType() = fun (): T = null!!
+
+    init {
+        devNull(fun (t: O) = t)
+        devNull(fun O.() = this)
+        devNull(fun (): O = null!!)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionAsExpression/WithoutBody.fir.kt b/compiler/testData/diagnostics/tests/functionAsExpression/WithoutBody.fir.kt
new file mode 100644
index 00000000000..ccb1f2408b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionAsExpression/WithoutBody.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+annotation class ann
+val bas = fun ()
+
+fun bar(a: Any) = fun ()
+
+fun outer() {
+    bar(fun ())
+    bar(l@ fun ())
+    bar(@ann fun ())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/DeprecatedSyntax.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/DeprecatedSyntax.fir.kt
new file mode 100644
index 00000000000..dac5ccb52fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/DeprecatedSyntax.fir.kt
@@ -0,0 +1,25 @@
+// !WITH_NEW_INFERENCE
+val receiver = { Int.(<!SYNTAX!><!>) <!SYNTAX!>-><!> }
+val receiverWithParameter = { Int.(<!UNRESOLVED_REFERENCE!>a<!>) <!SYNTAX!>-><!> }
+
+val receiverAndReturnType = { Int.(<!SYNTAX!><!>)<!SYNTAX!>: Int ->  5<!> }
+val receiverAndReturnTypeWithParameter = { Int.(<!UNRESOLVED_REFERENCE!>a<!><!SYNTAX!><!SYNTAX!><!>: Int): Int ->  5<!> }
+
+val returnType = { (<!SYNTAX!><!>): Int -> 5 }
+val returnTypeWithParameter = { (<!UNRESOLVED_REFERENCE!>b: Int<!>): Int -> 5 }
+
+val receiverWithFunctionType = { ((Int)<!SYNTAX!><!> <!SYNTAX!>-> Int).() -><!> }
+
+val parenthesizedParameters = { (<!UNRESOLVED_REFERENCE!>a: Int<!>) -> }
+val parenthesizedParameters2 = { (<!UNRESOLVED_REFERENCE!>b<!>) -> }
+
+val none = { -> }
+
+
+val parameterWithFunctionType = { a: ((Int) -> Int) -> <!SYNTAX!><!>} // todo fix parser
+
+val newSyntax = { a: Int -> }
+val newSyntax1 = { a, b -> }
+val newSyntax2 = { a: Int, b: Int -> }
+val newSyntax3 = { a, b: Int -> }
+val newSyntax4 = { a: Int, b -> }
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/ExpectedParameterTypeMismatchVariance.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/ExpectedParameterTypeMismatchVariance.fir.kt
new file mode 100644
index 00000000000..65b92ccea1f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/ExpectedParameterTypeMismatchVariance.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_ANONYMOUS_PARAMETER
+package a
+
+interface Super
+interface Trait : Super
+class Sub : Trait
+
+fun foo(f: (Trait) -> Trait) = f
+
+fun test(s: Sub) {
+    foo {
+        t: Super -> s
+    }
+    foo {
+        t: Trait -> s
+    }
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(fun(t: Sub) = s)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(fun(t): Super = s)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/ExpectedParametersTypesMismatch.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/ExpectedParametersTypesMismatch.fir.kt
new file mode 100644
index 00000000000..ac97071f7f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/ExpectedParametersTypesMismatch.fir.kt
@@ -0,0 +1,45 @@
+// !WITH_NEW_INFERENCE
+package a
+
+fun foo0(f: () -> String) = f
+fun foo1(f: (Int) -> String) = f
+fun foo2(f: (Int, String) -> String) = f
+
+fun test1() {
+    foo0 {
+        ""
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo0<!> {
+        s: String-> ""
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo0<!> {
+        x, y -> ""
+    }
+
+    foo1 {
+        ""
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo1<!> {
+        s: String -> ""
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo1<!> {
+        x, y -> ""
+    }
+    foo1 {
+        -> 42
+    }
+
+
+    foo2 {
+        ""
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo2<!> {
+        s: String -> ""
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo2<!> {
+        x -> ""
+    }
+    foo2 {
+         -> 42
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/LabeledFunctionLiterals.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/LabeledFunctionLiterals.fir.kt
new file mode 100644
index 00000000000..1d4a71b2a7b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/LabeledFunctionLiterals.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+package h
+
+//traits to make ambiguity with function literal as an argument
+interface A
+interface B
+interface C: A, B
+
+fun <T> foo(a: A, f: () -> T): T = f()
+fun <T> foo(b: B, f: () -> T): T = f()
+
+fun test(c: C) {
+    <!AMBIGUITY!>foo<!>(c) f@ {
+        c!!
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/assignmentOperationInLambda.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/assignmentOperationInLambda.fir.kt
new file mode 100644
index 00000000000..de80476b1b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/assignmentOperationInLambda.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+fun test(bal: Array<Int>) {
+    var bar = 4
+
+    val a = { bar += 4 }
+    checkSubtype<() -> Unit>(a)
+
+    val b = { bar = 4 }
+    checkSubtype<() -> Unit>(b)
+
+    val c = { bal[2] = 3 }
+    checkSubtype<() -> Unit>(c)
+
+    val d = run { bar += 4 }
+    checkSubtype<Unit>(d)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/assignmentOperationInLambdaWithExpectedType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/assignmentOperationInLambdaWithExpectedType.fir.kt
new file mode 100644
index 00000000000..b6362529419
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/assignmentOperationInLambdaWithExpectedType.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+fun test(bal: Array<Int>) {
+    var bar = 4
+
+    val a: () -> Unit = { bar += 4 }
+
+    val b: () -> Int = { bar = 4 }
+
+    val c: () -> UNRESOLVED = { bal[2] = 3 }
+
+    val d: () -> Int = { bar += 4 }
+
+    val e: Unit = run { bar += 4 }
+
+    val f: Int = run { bar += 4 }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/complexInference.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/complexInference.fir.kt
new file mode 100644
index 00000000000..11a8998209f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/complexInference.fir.kt
@@ -0,0 +1,48 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+data class A(val x: Int, val y: String)
+data class B(val u: Double, val w: Short)
+
+// first parameter of the functional type of 'x' can only be inferred from a lambda parameter explicit type specification
+fun <X, Y> foo(y: Y, x: (X, Y) -> Unit) {}
+
+fun bar(aInstance: A, bInstance: B) {
+    foo("") {
+        (<!UNRESOLVED_REFERENCE!>a<!>, <!UNRESOLVED_REFERENCE!>b<!>): A, c ->
+        a <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        b <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        c checkType { _<String>() }
+    }
+
+    foo(aInstance) {
+        a: String, (b, c) ->
+        a checkType { _<String>() }
+        b checkType { _<Int>() }
+        c checkType { _<String>() }
+    }
+
+    foo(bInstance) {
+        (a, b): A, (c, d) ->
+        <!UNRESOLVED_REFERENCE!>a<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        <!UNRESOLVED_REFERENCE!>b<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        c checkType { _<Double>() }
+        d checkType { _<Short>() }
+    }
+
+    foo(bInstance) {
+        (a, b), (c, d) ->
+        <!UNRESOLVED_REFERENCE!>a<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        <!UNRESOLVED_REFERENCE!>b<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        c checkType { _<Double>() }
+        d checkType { _<Short>() }
+    }
+
+    foo<A, B>(bInstance) {
+        (a, b), (c, d) ->
+        <!UNRESOLVED_REFERENCE!>a<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        <!UNRESOLVED_REFERENCE!>b<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        c checkType { _<Double>() }
+        d checkType { _<Short>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/extensionComponents.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/extensionComponents.fir.kt
new file mode 100644
index 00000000000..4eed101c9a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/extensionComponents.fir.kt
@@ -0,0 +1,53 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A
+
+operator fun A.component1() = 1
+operator fun A.component2() = ""
+
+class B
+
+class D {
+    operator fun A.component1() = 1.0
+    operator fun A.component2() = ' '
+
+    operator fun B.component1() = 1.0
+    operator fun B.component2() = ' '
+}
+
+fun foo(block: (A) -> Unit) { }
+fun foobaz(block: D.(B) -> Unit) { }
+fun foobar(block: D.(A) -> Unit) { }
+
+fun bar() {
+    foo { (a, b) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    foo { (a: Int, b: String) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    // From KEEP: Component-functions are resolved in the same scope as the first statement of the lambda
+    foobaz { (a, b) ->
+        a checkType { _<Double>() }
+        b checkType { _<Char>() }
+    }
+
+    // From KEEP: Component-functions are resolved in the same scope as the first statement of the lambda
+    // So `component1`/`component2` for lambda parameters were resolved to member extensions
+    foobar { (a, b) ->
+        a checkType { _<Double>() }
+        b checkType { _<Char>() }
+    }
+
+    // the following code fails with exception, see KT-13873
+//    foobarbaz {
+//        component1: B.() -> Int,
+//        component2: B.() -> String,
+//        (a, b): B ->
+//
+//    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/inferredFunctionalType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/inferredFunctionalType.fir.kt
new file mode 100644
index 00000000000..43835ece222
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/inferredFunctionalType.fir.kt
@@ -0,0 +1,34 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+data class A(val x: Int, val y: String)
+data class B(val u: Double, val w: Short)
+
+fun <T> Iterable<T>.foo(x: (T) -> Unit) {}
+
+fun bar(aList: List<A>) {
+    aList.foo { (a, b) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    aList.foo { (a: Int, b: String) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    aList.foo { (a, b): A ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    aList.foo { (a: String, b) ->
+        a checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+        b checkType { _<String>() }
+    }
+
+    aList.foo { (a, b): B ->
+        b checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+        a checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/modifiers.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/modifiers.fir.kt
new file mode 100644
index 00000000000..c39cd83275e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/modifiers.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+data class A(val x: Int, val y: String)
+
+fun foo(block: (A) -> Unit) { }
+
+@Target(AnnotationTarget.VALUE_PARAMETER)
+annotation class Ann
+
+fun bar() {
+    foo { (private inline a, @Ann b) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/noExpectedType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/noExpectedType.fir.kt
new file mode 100644
index 00000000000..6fb33e99ee2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/noExpectedType.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+data class A(val x: Int, val y: String)
+
+fun bar() {
+    val x = { (<!UNRESOLVED_REFERENCE!>a<!>, <!UNRESOLVED_REFERENCE!>b<!>): A ->
+        a <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        b <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+
+    x checkType { <!UNRESOLVED_REFERENCE!>_<!><(A) -> Unit>() }
+
+    val y = { (<!UNRESOLVED_REFERENCE!>a: Int<!>, <!UNRESOLVED_REFERENCE!>b<!>): A ->
+        a checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        b <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><(A) -> Unit>() }
+
+    val y2 = { (<!UNRESOLVED_REFERENCE!>a: Number<!>, <!UNRESOLVED_REFERENCE!>b<!>): A ->
+        a checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        b <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+
+    y2 checkType { <!UNRESOLVED_REFERENCE!>_<!><(A) -> Unit>() }
+
+    val z = { (<!UNRESOLVED_REFERENCE!>a: Int<!>, <!UNRESOLVED_REFERENCE!>b: String<!>) ->
+        a checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        b checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/redeclaration.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/redeclaration.fir.kt
new file mode 100644
index 00000000000..61c556743b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/redeclaration.fir.kt
@@ -0,0 +1,30 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+data class A(val x: Int, val y: String)
+data class B(val u: Double, val w: Short)
+
+fun foo(block: (A, B) -> Unit) { }
+
+fun bar() {
+    foo { (a, a), b ->
+        a checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+        b checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    }
+
+    foo { (a, b), a ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    foo { a, (a, b) ->
+        a checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+        b checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    }
+
+    foo { (a, b), (c, b) ->
+        <!UNRESOLVED_REFERENCE!>a<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        b checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+        c checkType { <!INAPPLICABLE_CANDIDATE!>_<!><B>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/shadowing.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/shadowing.fir.kt
new file mode 100644
index 00000000000..5554968db9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/shadowing.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+data class A(val x: Int, val y: String)
+
+fun foo(block: (A) -> Unit) { }
+
+fun bar(a: Double) {
+    val b = 1.toShort()
+    // Do not report NAME_SHADOWING on lambda destructured parameter, the same way as for common parameters
+    foo { (a, b) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    foo { (c, d) ->
+        c checkType { _<Int>() }
+        d checkType { _<String>() }
+
+        foo { (a, c) ->
+            a checkType { _<Int>() }
+            c checkType { _<String>() }
+            d checkType { _<String>() }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/simple.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/simple.fir.kt
new file mode 100644
index 00000000000..e7e9af3047b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/simple.fir.kt
@@ -0,0 +1,54 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+data class A(val x: Int, val y: String)
+data class B(val u: Double, val w: Short)
+
+fun foo(block: (A) -> Unit) { }
+fun foobar(block: (A, B) -> Unit) { }
+
+fun bar() {
+    foo { (a, b) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    foo { (a: Int, b: String) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    foo { (a, b): A ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+
+    foobar { (a, b), c ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+        c checkType { _<B>() }
+    }
+
+    foobar { a, (b, c) ->
+        a checkType { _<A>() }
+        b checkType { _<Double>() }
+        c checkType { _<Short>() }
+    }
+
+    foobar { (a, b), (c, d) ->
+        <!UNRESOLVED_REFERENCE!>a<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        <!UNRESOLVED_REFERENCE!>b<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        c checkType { _<Double>() }
+        d checkType { _<Short>() }
+    }
+
+    foo { (a: String, b) ->
+        a checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+        b checkType { _<String>() }
+    }
+
+    foo { (a, b): B ->
+        a checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Double>() }
+        b checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Short>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/underscore.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/underscore.fir.kt
new file mode 100644
index 00000000000..f08a2af15d7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/underscore.fir.kt
@@ -0,0 +1,63 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+data class A(val x: Int, val y: String)
+data class B(val u: Double, val w: Short)
+
+fun foo(block: (A) -> Unit) { }
+
+fun bar() {
+    foo { (_, b) ->
+        _.hashCode()
+        b checkType { _<String>() }
+    }
+
+    foo { (a, _) ->
+        a checkType { _<Int>() }
+        _.hashCode()
+    }
+
+    foo { (_, _) ->
+        _.hashCode()
+    }
+
+    foo { (_: Int, b: String) ->
+        _.hashCode()
+        b checkType { _<String>() }
+    }
+
+    foo { (a: Int, _: String) ->
+        a checkType { _<Int>() }
+        _.hashCode()
+    }
+
+    foo { (_: Int, _: String) ->
+        _.hashCode()
+    }
+
+    foo { (_, _): A ->
+        _.hashCode()
+    }
+
+    foo { (`_`, _) ->
+        _ checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+    }
+
+    foo { (_, `_`) ->
+        _ checkType { _<String>() }
+    }
+
+    foo { (`_`, `_`) ->
+        _ checkType { _<String>() }
+    }
+
+    foo { (_: String, b) ->
+        _.hashCode()
+        b checkType { _<String>() }
+    }
+
+    foo { (_, b): B ->
+        _.hashCode()
+        b checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Short>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/unsupportedFeature.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/unsupportedFeature.fir.kt
new file mode 100644
index 00000000000..96aa55ce781
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/unsupportedFeature.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: -DestructuringLambdaParameters
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+data class A(val x: Int, val y: String)
+
+fun foo(block: (A) -> Unit) { }
+
+fun bar() {
+    foo { (a, b) ->
+        a checkType { _<Int>() }
+        b checkType { _<String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/unusedParameters.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/unusedParameters.fir.kt
new file mode 100644
index 00000000000..b2de6659aee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/destructuringInLambdas/unusedParameters.fir.kt
@@ -0,0 +1,43 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+data class A(val x: Int, val y: String)
+data class B(val u: Double, val w: Short)
+
+fun foo(block: (A) -> Unit) { }
+fun foobar(block: (A, B) -> Unit) { }
+
+fun bar() {
+    foo { (a, b) ->
+        a checkType { _<Int>() }
+    }
+
+    foo { (a, b) ->
+        b checkType { _<String>() }
+    }
+
+    foo { (a: Int, b: String) ->
+        a checkType { _<Int>() }
+    }
+
+    foo { (a: Int, b: String) ->
+        b checkType { _<String>() }
+    }
+
+    foobar { (a, b), c ->
+        a checkType { _<Int>() }
+    }
+
+    foobar { a, (b, c) ->
+        c checkType { _<Short>() }
+    }
+
+    foobar { (a, b), (c, d) ->
+        <!UNRESOLVED_REFERENCE!>a<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+        d checkType { _<Short>() }
+    }
+
+    foobar { (a, b), (c, d) ->
+        <!UNRESOLVED_REFERENCE!>b<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        c checkType { _<Double>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/functionExpressionAsLastExpressionInBlock.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/functionExpressionAsLastExpressionInBlock.fir.kt
new file mode 100644
index 00000000000..61f1611b10e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/functionExpressionAsLastExpressionInBlock.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_EXPRESSION
+
+import java.util.HashSet
+
+fun test123() {
+    val g: (Int) -> Unit = if (true) {
+        val set = HashSet<Int>()
+        fun (i: Int) {
+            set.add(i)
+        }
+    }
+    else {
+        { it -> it }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/functionLIteralInBlockInIf.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/functionLIteralInBlockInIf.fir.kt
new file mode 100644
index 00000000000..dbb2f2e3c3f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/functionLIteralInBlockInIf.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+fun test() {
+    val a = if (true) {
+        val x = 1
+        ({ x })
+    } else {
+        { 2 }
+    }
+    a checkType {  <!UNRESOLVED_REFERENCE!>_<!><() -> Int>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralAsArgumentForFunction.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralAsArgumentForFunction.fir.kt
new file mode 100644
index 00000000000..2becbe62950
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralAsArgumentForFunction.fir.kt
@@ -0,0 +1,25 @@
+class Log
+
+data class CalculatedVariable(
+    val idString: String,
+    val presentableName: String,
+    val units: String,
+    val function: (Log) -> ((TimeIndex) -> Any?)?,
+    val converter: (Any) -> Double
+) {
+    constructor(idString: String, presentableName: String, units: String, function: (Log) -> ((TimeIndex) -> Double?)?)
+            : this(idString, presentableName, units, function, { it as Double })
+}
+
+object CalculatedVariables {
+    val x = CalculatedVariable(
+        "A",
+        "B",
+        "C",
+        fun(log: Log): ((TimeIndex) -> Double?)? {
+            return { 0.0 }
+        }
+    )
+}
+
+class TimeIndex
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralInIf.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralInIf.fir.kt
new file mode 100644
index 00000000000..b007414c1bd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralInIf.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_EXPRESSION
+
+import java.util.HashSet
+
+fun test123() {
+    val g: (Int) -> Unit = if (true) {
+        val set = HashSet<Int>();
+        { i ->
+            set.add(i)
+        }
+    }
+    else {
+        { it -> it }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralWithoutArgumentList.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralWithoutArgumentList.fir.kt
new file mode 100644
index 00000000000..4ff47f19893
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/functionLiteralWithoutArgumentList.fir.kt
@@ -0,0 +1,7 @@
+// !CHECK_TYPE
+fun <T> id(t: T) = t
+
+fun foo() {
+    val i = id { 22 } //type inference error: no information for parameter
+    i checkType { <!UNRESOLVED_REFERENCE!>_<!><()->Int>() }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/genericFunctionalTypeOnRHSOfPlusAssign.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/genericFunctionalTypeOnRHSOfPlusAssign.fir.kt
new file mode 100644
index 00000000000..6d60bef632b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/genericFunctionalTypeOnRHSOfPlusAssign.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> Iterable<T>.filter(predicate: (T) -> Boolean): List<T> = TODO()
+operator fun <T> Collection<T>.plus(elements: Iterable<T>): List<T> = TODO()
+
+fun stringCollection(): Collection<String> = TODO()
+
+fun <K> test(c: Collection<K>) {
+    var variants = stringCollection()
+    variants += variants.filter { true }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/higherOrderCallMissingParameters.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/higherOrderCallMissingParameters.fir.kt
new file mode 100644
index 00000000000..7b5618f7a0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/higherOrderCallMissingParameters.fir.kt
@@ -0,0 +1,16 @@
+// See KT-7813: Call to functional parameter with missing argument: no error detected but compiler crashes
+
+fun foo(p: (Int, () -> Int) -> Unit) {
+    // Errors except last call
+    <!INAPPLICABLE_CANDIDATE!>p<!> { 1 }
+    <!INAPPLICABLE_CANDIDATE!>p<!>() { 2 }
+    p(3) { 4 }
+}
+
+fun bar(p: (String, Any, () -> String) -> Unit) {
+    // Errors except last call
+    <!INAPPLICABLE_CANDIDATE!>p<!> { "" }
+    <!INAPPLICABLE_CANDIDATE!>p<!>() { "x" }
+    <!INAPPLICABLE_CANDIDATE!>p<!>("y") { "z" }
+    p("v", Any()) { "w" }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt11733.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt11733.fir.kt
new file mode 100644
index 00000000000..12b0dc6b6b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt11733.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+interface Predicate<T>
+
+fun <T> Predicate(x: (T?) -> Boolean): Predicate<T> = null!!
+
+fun foo() {
+    process(Predicate {
+        x -> x checkType { _<String?>() }
+
+        true
+    })
+}
+
+fun process(x: Predicate<String>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt11733_1.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt11733_1.fir.kt
new file mode 100644
index 00000000000..76a64dd2123
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt11733_1.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+// FILE: Predicate.java
+import org.jetbrains.annotations.NotNull;
+
+public interface Predicate<T extends CharSequence> {
+    // Same effect with @Nullable here
+    boolean invoke(@NotNull T t);
+}
+// FILE: Main.kt
+fun process(x: Predicate<String>) {}
+fun main() {
+    process(Predicate { x -> x checkType { _<String>() }
+        true
+    })
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt16016.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt16016.fir.kt
new file mode 100644
index 00000000000..8cf79ac6dfc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt16016.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+val la = { a -> }
+val las = { a: Int -> }
+
+val larg = <!UNRESOLVED_REFERENCE!>{ a -> }(123)<!>
+val twoarg = <!UNRESOLVED_REFERENCE!>{ a, b: String, c -> }(123, "asdf", 123)<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt2906.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt2906.fir.kt
new file mode 100644
index 00000000000..63c81f0c12d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt2906.fir.kt
@@ -0,0 +1,22 @@
+//KT-2906 If function parameter/variable is invoked in closure using parenthesis syntax, in IDEA it is not highlighted as captured in closure
+
+package bug
+
+public fun foo1(bar: () -> Unit) {
+    run {
+        bar() // ERROR: not highlighted as "captured in closure"
+    }
+}
+
+public fun foo2(bar: () -> Unit) {
+    run {
+        bar.invoke() // CORRECT: highlighted as "captured in closure"
+    }
+}
+
+fun main() {
+    foo1 { println ("foo1")} // prints "foo1"
+    foo2 { println ("foo2")} // prints "foo2"
+}
+
+fun println(s: String) = s
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt3343.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt3343.fir.kt
new file mode 100644
index 00000000000..8ed60159149
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt3343.fir.kt
@@ -0,0 +1,25 @@
+// KT-3343 Type mismatch when function literal consists of try-catch with Int returning call, and Unit is expected
+
+fun main() {
+    "hello world".prt{
+        try{
+            print(it)
+            log("we are printing")
+        }
+        catch(e : Exception){
+            log("Exception")
+        }
+    }
+}
+
+fun log(str : String) : Int{
+    print("logging $str")
+    return 0
+}
+
+fun print(obj: Any) {}
+
+
+fun String.prt(action : (String) -> Unit){
+    action(this)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt4529.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt4529.fir.kt
new file mode 100644
index 00000000000..38833e5c513
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt4529.fir.kt
@@ -0,0 +1,19 @@
+//KT-4529 Lambdas are analyzed improperly in an infix call nested inside a println
+
+class G {
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun foo(bar: (Int) -> Int) = bar<!>
+}
+
+fun main() {
+    use(
+            G().foo {it + 11} // no error
+    )
+    use(
+            G() foo {it + 11} // ERROR
+    )
+    use(
+            G() foo ({it + 1}) // 2 ERRORs
+    )
+}
+
+fun use(a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt6541_extensionForExtensionFunction.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt6541_extensionForExtensionFunction.fir.kt
new file mode 100644
index 00000000000..69913673c8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt6541_extensionForExtensionFunction.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo
+fun (Foo.() -> Unit).invoke(b : Foo.() -> Unit)  {}
+
+object Z {
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun add(b : Foo.() -> Unit) : Z = Z<!>
+}
+
+val t2 = Z <!INAPPLICABLE_CANDIDATE!>add<!> { } { }
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt6869.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt6869.fir.kt
new file mode 100644
index 00000000000..3e504a8e29c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt6869.fir.kt
@@ -0,0 +1,10 @@
+fun main() {
+    var list = listOf(1)
+
+    val a: Int? = 2
+
+    a?.let { list += it }
+}
+
+operator fun <T> Iterable<T>.plus(element: T): List<T> = null!!
+fun <T> listOf(vararg values: T): List<T> = null!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/kt7383_starProjectedFunction.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/kt7383_starProjectedFunction.fir.kt
new file mode 100644
index 00000000000..2fc651f8136
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/kt7383_starProjectedFunction.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+// KT-7383 Assertion failed when a star-projection of function type is used
+
+fun foo() {
+    val f : Function1<*, *> = { x -> x.toString() }
+    f(1)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/prematurelyAnalyzingLambdaWhileFixingTypeVariableForAnotherArgument.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/prematurelyAnalyzingLambdaWhileFixingTypeVariableForAnotherArgument.fir.kt
new file mode 100644
index 00000000000..092ff35c70c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/prematurelyAnalyzingLambdaWhileFixingTypeVariableForAnotherArgument.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !LANGUAGE: +NewInference
+// SKIP_TXT
+// Issue: KT-35168
+
+class Inv<T>
+
+// Before the fix, here we had an exception while fixing a type variable for Inv due to prematurely analyzing a lambda
+// The exception was: "UninitializedPropertyAccessException: lateinit property subResolvedAtoms has not been initialized"
+class Foo<T>(x: (T) -> T, y: Inv<Any>)
+
+fun bar() {
+    Foo<Any>({}, Inv())
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/AutoLabels.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/AutoLabels.fir.kt
new file mode 100644
index 00000000000..f25dfe60cdb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/AutoLabels.fir.kt
@@ -0,0 +1,22 @@
+fun f() {
+    foo {
+        return@foo 1
+    }
+    foo({
+        return@foo 1
+    }
+    )
+    foo(a = {
+        return@foo 1
+    })
+
+    foo {
+        foo {
+            return@foo 1
+        }
+        return@foo 1
+    }
+}
+
+fun foo(a: Any) {}
+
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/AutoLabelsNonLocal.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/AutoLabelsNonLocal.fir.kt
new file mode 100644
index 00000000000..ddf260e5d7b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/AutoLabelsNonLocal.fir.kt
@@ -0,0 +1,11 @@
+fun f() {
+    foo {
+        bar {
+            return@foo 1
+        }
+        return@foo 1
+    }
+}
+
+fun foo(a: Any) {}
+fun bar(a: Any) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/ForbiddenNonLocalReturnNoType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/ForbiddenNonLocalReturnNoType.fir.kt
new file mode 100644
index 00000000000..921de7f2663
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/ForbiddenNonLocalReturnNoType.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+fun test() {
+    run {return}
+    run {}
+}
+
+fun test2() {
+    run {return@test2}
+    run {}
+}
+
+fun test3() {
+    fun test4() {
+        run {return@test3}
+        run {}
+    }
+}
+
+fun <T> run(f: () -> T): T { return f() }
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/IfInReturnedExpression.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/IfInReturnedExpression.fir.kt
new file mode 100644
index 00000000000..05cd4632d05
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/IfInReturnedExpression.fir.kt
@@ -0,0 +1,9 @@
+val flag = true
+
+interface I
+class A(): I
+class B(): I
+
+val a = l@ {
+    return@l if (flag) A() else B()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/IfWithoutElse.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/IfWithoutElse.fir.kt
new file mode 100644
index 00000000000..cf5888dab3d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/IfWithoutElse.fir.kt
@@ -0,0 +1,15 @@
+val flag = true
+
+// type of a was checked by txt
+val a/*: () -> Any*/ = l@ {
+    if (flag) return@l 4
+}
+
+val b/*: () -> Int */ = l@ {
+    if (flag) return@l 4
+    5
+}
+
+val c/*: () -> Unit */ = l@ {
+    if (flag) 4
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/IfWithoutElseWithExplicitType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/IfWithoutElseWithExplicitType.fir.kt
new file mode 100644
index 00000000000..1bba3f19ba7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/IfWithoutElseWithExplicitType.fir.kt
@@ -0,0 +1,22 @@
+val flag = true
+
+val a: () -> Int = l@ {
+    if (flag) return@l 4
+}
+
+val b: () -> Unit = l@ {
+    if (flag) return@l 4
+}
+
+val c: () -> Any = l@ {
+    if (flag) return@l 4
+}
+
+val d: () -> Int = l@ {
+    if (flag) return@l 4
+    5
+}
+
+val e: () -> Int = l@ {
+    if (flag) 4
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LambdaWithParameter.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LambdaWithParameter.fir.kt
new file mode 100644
index 00000000000..777ef9e8a48
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LambdaWithParameter.fir.kt
@@ -0,0 +1,17 @@
+val flag = true
+
+val a /*: (Int) -> String */ = l@ {
+    i: Int ->
+    if (i == 0) return@l i.toString()
+
+    "Ok"
+}
+
+fun <T> foo(f: (Int) -> T): T = f(0)
+
+val b /*:String */ = foo {
+    i ->
+    if (i == 0) return@foo i.toString()
+
+    "Ok"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalAndNonLocalReturnInLambda.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalAndNonLocalReturnInLambda.fir.kt
new file mode 100644
index 00000000000..dc0204cf421
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalAndNonLocalReturnInLambda.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+fun test2(a: Int) {
+    val x = run f@{
+      if (a > 0) return
+      return@f 1
+    }
+    checkSubtype<Int>(x)
+}
+
+fun <T> run(f: () -> T): T { return f() }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelNoParens.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelNoParens.fir.kt
new file mode 100644
index 00000000000..a0417a8fcca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelNoParens.fir.kt
@@ -0,0 +1,6 @@
+// !CHECK_TYPE
+
+fun test2() {
+    val x = run f@{return@f 1}
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelParens.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelParens.fir.kt
new file mode 100644
index 00000000000..4e10c2dba99
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelParens.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+fun test() {
+    val x = run(f@{return@f 1})
+    checkSubtype<Int>(x)
+}
+
+
+fun test1() {
+    val x = run(l@{return@l 1})
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnHasTypeNothing.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnHasTypeNothing.fir.kt
new file mode 100644
index 00000000000..d94c56a54d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnHasTypeNothing.fir.kt
@@ -0,0 +1,7 @@
+// !CHECK_TYPE
+
+fun test() {
+    run f@{
+        checkSubtype<Nothing>(return@f 1)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedFunction.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedFunction.fir.kt
new file mode 100644
index 00000000000..0aad15f653f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedFunction.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+fun test() {
+    val x = run f@{
+      fun local(a: Int): String {
+        if (a > 0) return "2"
+        return@local "3"
+      }
+      return@f 1
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedLambda.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedLambda.fir.kt
new file mode 100644
index 00000000000..db53a69beab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedLambda.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+fun test() {
+    val x = run f@{
+      run ff@ {
+        return@ff "2"
+      }
+      return@f 1
+    }
+    checkSubtype<Int>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNoCoercionToUnit.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNoCoercionToUnit.fir.kt
new file mode 100644
index 00000000000..998fc7d5291
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNoCoercionToUnit.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+fun test(a: Int) {
+    run f@{
+      if (a > 0) return@f
+      else return@f 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNull.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNull.fir.kt
new file mode 100644
index 00000000000..2e9d8675ca3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNull.fir.kt
@@ -0,0 +1,14 @@
+class A
+val flag = true
+
+val a /*: () -> A?*/ = l@ {
+    if (flag) return@l null
+
+    A()
+}
+
+val b /*: () -> A?*/ = l@ {
+    if (flag) return@l null
+
+    return@l A()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnSecondUnit.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnSecondUnit.fir.kt
new file mode 100644
index 00000000000..7f02acdf15b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnSecondUnit.fir.kt
@@ -0,0 +1,6 @@
+val flag = true
+
+val a = b@ {
+    if (flag) return@b 4
+    return@b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnit.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnit.fir.kt
new file mode 100644
index 00000000000..5d19e6ac54c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnit.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+fun test(a: Int) {
+    val x = run f@{
+      if (a > 0) return@f
+      else return@f Unit
+    }
+    checkSubtype<Unit>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnitAndDontCareType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnitAndDontCareType.fir.kt
new file mode 100644
index 00000000000..96941889555
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnitAndDontCareType.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+val flag = true
+
+// type of a was checked by txt
+val a = run { // () -> Unit
+    return@run
+}
+
+// Unit
+val b = run {
+    if (flag) return@run
+    5
+}
+
+// Unit
+val c = run {
+    if (flag) return@run
+
+    return@run 4
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnitWithBodyExpression.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnitWithBodyExpression.fir.kt
new file mode 100644
index 00000000000..bd67e82f22d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnitWithBodyExpression.fir.kt
@@ -0,0 +1,7 @@
+val flag = true
+
+// type of lambda was checked by txt
+val a = b@ { // () -> Unit
+    if (flag) return@b
+    else 54
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnWithExpectedType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnWithExpectedType.fir.kt
new file mode 100644
index 00000000000..ca7f7434a65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnWithExpectedType.fir.kt
@@ -0,0 +1,9 @@
+fun <T> listOf(): List<T> = null!!
+fun <T> listOf(vararg values: T): List<T> = null!!
+
+val flag = true
+
+val a: () -> List<Int> = l@ {
+    if (flag) return@l listOf()
+    listOf(5)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnWithExplicitUnit.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnWithExplicitUnit.fir.kt
new file mode 100644
index 00000000000..1c12596f99a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnWithExplicitUnit.fir.kt
@@ -0,0 +1,16 @@
+val flag = true
+
+// type of lambda was checked by txt
+val a = l@ { // () -> Any
+    if (flag) return@l 4
+    return@l Unit
+}
+
+val b = l@ { // () -> Any
+    if (flag) return@l Unit
+    5
+}
+
+val c = l@ { // () -> Unit
+    if (flag) return@l Unit
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnsWithExplicitReturnType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnsWithExplicitReturnType.fir.kt
new file mode 100644
index 00000000000..ac0c76d48db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnsWithExplicitReturnType.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+fun test(a: Int) {
+    run<Int>f@{
+      if (a > 0) return@f ""
+      return@f 1
+    }
+
+    run<Int>{ "" }
+    run<Int>{ 1 }
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/MixedReturnsFromLambda.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/MixedReturnsFromLambda.fir.kt
new file mode 100644
index 00000000000..1ee85944f8b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/MixedReturnsFromLambda.fir.kt
@@ -0,0 +1,14 @@
+// !CHECK_TYPE
+
+interface A
+interface B: A
+interface C: A
+
+
+fun test(a: C, b: B) {
+    val x = run f@{
+      if (a != b) return@f a
+      b
+    }
+    checkSubtype<A>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/NoCommonSystem.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/NoCommonSystem.fir.kt
new file mode 100644
index 00000000000..22e46bb749e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/NoCommonSystem.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> = null!!
+fun <T> listOf(): List<T> = null!!
+fun <T> listOf(vararg values: T): List<T> = null!!
+
+fun commonSystemFailed(a: List<Int>) {
+    a.map {
+        if (it == 0) return@map listOf(it)
+        listOf()
+    }
+    a.map {
+        if (it == 0) return@map listOf()
+        listOf(it)
+    }
+    a.map {
+        if (it == 0) listOf()
+        else listOf(it)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/SmartCast.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/SmartCast.fir.kt
new file mode 100644
index 00000000000..a9649e4b4db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/SmartCast.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+// KT-6822 Smart cast doesn't work inside local returned expression in lambda 
+
+val a /* :(Int?) -> Int? */ = l@ { it: Int? -> // but must be (Int?) -> Int
+    if (it != null) return@l it
+    5
+}
+
+fun <R> let(f: (Int?) -> R): R = null!!
+
+val b /*: Int? */ = let { // but must be Int
+    if (it != null) return@let it
+    5
+}
+
+val c /*: Int*/ = let {
+    if (it != null) it else 5
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/SmartCastWithExplicitType.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/SmartCastWithExplicitType.fir.kt
new file mode 100644
index 00000000000..fe80cb50b70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/SmartCastWithExplicitType.fir.kt
@@ -0,0 +1,17 @@
+// KT-6822 Smart cast doesn't work inside local returned expression in lambda
+
+val a : (Int?) -> Int = l@ {
+    if (it != null) return@l it
+    5
+}
+
+fun <R> let(f: (Int?) -> R): R = null!!
+
+val b: Int = let {
+    if (it != null) return@let it
+    5
+}
+
+val c: Int = let {
+    if (it != null) it else 5
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/return/unresolvedReferenceInReturnBlock.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/return/unresolvedReferenceInReturnBlock.fir.kt
new file mode 100644
index 00000000000..b015a35ffd5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/return/unresolvedReferenceInReturnBlock.fir.kt
@@ -0,0 +1,9 @@
+val a = l@ {
+    return@l <!UNRESOLVED_REFERENCE!>r<!>
+}
+
+val b = l@ {
+    if ("" == "OK") return@l
+
+    return@l <!UNRESOLVED_REFERENCE!>r<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/returnNull.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/returnNull.fir.kt
new file mode 100644
index 00000000000..a8d7942f421
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/returnNull.fir.kt
@@ -0,0 +1,10 @@
+package m
+
+interface Element
+
+fun test(handlers: Map<String, Element.()->Unit>) {
+
+    handlers.getOrElse("name", { null })
+}
+
+fun <K,V> Map<K,V>.getOrElse(key: K, defaultValue: ()-> V) : V = throw Exception("$key $defaultValue")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/returnNullWithReturn.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/returnNullWithReturn.fir.kt
new file mode 100644
index 00000000000..491a77d8ad3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/returnNullWithReturn.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+package m
+
+interface Element
+
+fun test(handlers: Map<String, Element.()->Unit>) {
+
+    handlers.getOrElse("name", l@ { return@l null })
+}
+
+fun <K,V> Map<K,V>.getOrElse(key: K, defaultValue: ()-> V) : V = throw Exception("$key $defaultValue")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/underscopeParameters.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/underscopeParameters.fir.kt
new file mode 100644
index 00000000000..89475115666
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/underscopeParameters.fir.kt
@@ -0,0 +1,48 @@
+// !CHECK_TYPE
+
+fun foo(block: (Int, String) -> Unit) { }
+fun foobar(block: (Double) -> Unit) { }
+
+fun bar() {
+    foo { _, b ->
+        _.hashCode()
+        b checkType { _<String>() }
+    }
+
+    foo { a, _ ->
+        a checkType { _<Int>() }
+        _.hashCode()
+    }
+
+    foo { _, _ ->
+        _.hashCode()
+    }
+
+    foo { _: Int, b: String ->
+        _.hashCode()
+        b checkType { _<String>() }
+    }
+
+    foo { a: Int, _: String ->
+        a checkType { _<Int>() }
+        _.hashCode()
+    }
+
+    foo { _: Int, _: String ->
+        _.hashCode()
+    }
+
+    foo { `_`, _ ->
+        _ checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+    }
+
+    foo { _, `_` ->
+        _ checkType { _<String>() }
+    }
+
+    foo { `_`, `_` ->
+        _ checkType { _<String>() }
+    }
+
+    foo(fun(x: Int, _: String) {})
+}
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/unusedLiteral.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/unusedLiteral.fir.kt
new file mode 100644
index 00000000000..1cc8477b6fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/unusedLiteral.fir.kt
@@ -0,0 +1,12 @@
+fun unusedLiteral(){
+    { ->
+        val i = 1
+    }
+}
+
+
+fun unusedLiteralInDoWhile(){
+    do{ ->
+            val i = 1
+    } while(false)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/functionLiterals/unusedLiteralInsideUnitLiteral.fir.kt b/compiler/testData/diagnostics/tests/functionLiterals/unusedLiteralInsideUnitLiteral.fir.kt
new file mode 100644
index 00000000000..48149e6bb47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/functionLiterals/unusedLiteralInsideUnitLiteral.fir.kt
@@ -0,0 +1,8 @@
+fun main() {
+    "".run {
+        {}
+    }
+}
+
+
+fun <T> T.run(f: (T) -> Unit): Unit = f(this)
diff --git a/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.fir.kt b/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.fir.kt
new file mode 100644
index 00000000000..e6f3a6df42c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/InconsistentTypeParameterBounds.fir.kt
@@ -0,0 +1,7 @@
+interface A
+interface B : A
+
+interface ListA : List<A>
+interface ListB : List<B>
+
+interface Z<T> where T : ListA, T : ListB
diff --git a/compiler/testData/diagnostics/tests/generics/Projections.fir.kt b/compiler/testData/diagnostics/tests/generics/Projections.fir.kt
new file mode 100644
index 00000000000..483b2e5a128
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/Projections.fir.kt
@@ -0,0 +1,54 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+class In<in T>() {
+    fun f(t : T) : Unit {}
+    fun f(t : Int) : Int = 1
+    fun f1(t : T) : Unit {}
+}
+
+class Out<out T>() {
+    fun f() : T {throw IllegalStateException()}
+    fun f(a : Int) : Int = a
+}
+
+class Inv<T>() {
+    fun f(t : T) : T = t
+    fun inf(t : T) : Unit {}
+    fun outf() : T {throw IllegalStateException()}
+}
+
+fun testInOut() {
+    In<String>().f("1");
+    (null as In<in String>).f("1")
+    (null as In<*>).f("1") // Wrong Arg
+
+    In<String>().f(1);
+    (null as In<in String>).f(1)
+    (null as In<*>).f(1);
+
+    Out<Int>().f(1)
+    (null as Out<out Int>).f(1)
+    (null as Out<*>).f(1)
+
+    Out<Int>().f()
+    (null as Out<out Int>).f()
+    (null as Out<*>).f()
+
+    Inv<Int>().f(1)
+    (null as Inv<in Int>).f(1)
+    (null as Inv<out Int>).f(1) // !!
+    (null as Inv<*>).f(1) // !!
+
+    Inv<Int>().inf(1)
+    (null as Inv<in Int>).inf(1)
+    (null as Inv<out Int>).inf(1) // !!
+    (null as Inv<*>).inf(1) // !!
+
+    Inv<Int>().outf()
+    checkSubtype<Int>((null as Inv<in Int>).outf()) // Type mismatch
+    (null as Inv<out Int>).outf()
+    (null as Inv<*>).outf()
+
+    Inv<Int>().<!INAPPLICABLE_CANDIDATE!>outf<!>(1) // Wrong Arg
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/PseudoRawTypes.fir.kt b/compiler/testData/diagnostics/tests/generics/PseudoRawTypes.fir.kt
new file mode 100644
index 00000000000..f4fee390b7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/PseudoRawTypes.fir.kt
@@ -0,0 +1,25 @@
+// JAVAC_EXPECTED_FILE
+// FILE: java/util/Collection.java
+package java.util;
+
+public class Collection {
+  public void foo() {}
+}
+
+// FILE: test/Usage.java
+package test;
+
+import java.util.*;
+
+public class Usage {
+  void foo(Collection c) {
+    c.foo();
+  }
+}
+
+// FILE: Kotlin.kt
+package test
+
+fun foo(u: Usage) {
+  u.foo(null)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/RawTypeInIsExpression.fir.kt b/compiler/testData/diagnostics/tests/generics/RawTypeInIsExpression.fir.kt
new file mode 100644
index 00000000000..e106601f1e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/RawTypeInIsExpression.fir.kt
@@ -0,0 +1,14 @@
+package p
+
+public fun foo(a: Any) {
+    a is Map<Int>
+    a is Map
+    a is Map<out Any?, Any?>
+    a is Map<*, *>
+    a is Map<<!SYNTAX!><!>>
+    a is List<Map>
+    a is List
+    a is Int
+
+    (a as Map) is Int
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/RawTypeInIsPattern.fir.kt b/compiler/testData/diagnostics/tests/generics/RawTypeInIsPattern.fir.kt
new file mode 100644
index 00000000000..f76110a228e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/RawTypeInIsPattern.fir.kt
@@ -0,0 +1,13 @@
+public fun foo(a: Any, b: Map) {
+    when (a) {
+        is Map<Int> -> {}
+        is Map -> {}
+        is Map<out Any?, Any?> -> {}
+        is Map<*, *> -> {}
+        is Map<<!SYNTAX!><!>> -> {}
+        is List<Map> -> {}
+        is List -> {}
+        is Int -> {}
+        else -> {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/RecursiveUpperBoundCheck.fir.kt b/compiler/testData/diagnostics/tests/generics/RecursiveUpperBoundCheck.fir.kt
new file mode 100644
index 00000000000..49811563193
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/RecursiveUpperBoundCheck.fir.kt
@@ -0,0 +1,3 @@
+open class C<T : C<T>>
+class TestOK : C<TestOK>()
+class TestFail : C<C<TestFail>>()
diff --git a/compiler/testData/diagnostics/tests/generics/RecursiveUpperBoundWithTwoArguments.fir.kt b/compiler/testData/diagnostics/tests/generics/RecursiveUpperBoundWithTwoArguments.fir.kt
new file mode 100644
index 00000000000..ceed755ac5d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/RecursiveUpperBoundWithTwoArguments.fir.kt
@@ -0,0 +1 @@
+class D<A : D<A, String>, B : D<A, B>>
diff --git a/compiler/testData/diagnostics/tests/generics/TypeParameterBounds.fir.kt b/compiler/testData/diagnostics/tests/generics/TypeParameterBounds.fir.kt
new file mode 100644
index 00000000000..3612db3e2f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/TypeParameterBounds.fir.kt
@@ -0,0 +1,23 @@
+// See KT-9438: Enforce the Single Instantiation Inheritance Rule for type parameters
+
+interface A
+
+interface B
+
+interface D<T>
+
+interface IncorrectF<T : D<A>> where T : D<B>
+
+interface CorrectF<T> where T : D<A>, T : D<B>
+
+interface G<T>
+
+interface IncorrectH<T : G<D<A>>> where T : G<D<T>>
+
+interface CorrectH<T> where T : G<D<A>>, T : G<D<B>>
+
+interface incorrectJ<T: G<D<T>>> where T : G<D<T?>>
+
+interface correctJ<T> where T : G<D<T>>, T : G<D<T?>>
+
+fun <T> bar() where T : D<A>, T : D<B> {}
diff --git a/compiler/testData/diagnostics/tests/generics/TypeParametersInTypeParameterBounds.fir.kt b/compiler/testData/diagnostics/tests/generics/TypeParametersInTypeParameterBounds.fir.kt
new file mode 100644
index 00000000000..327e1d0d831
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/TypeParametersInTypeParameterBounds.fir.kt
@@ -0,0 +1,15 @@
+interface I1
+interface I2
+open class C
+
+interface A1<K, V> where V : K, V : K
+interface A2<K, V, W> where W : K, W : V
+interface A3<K, V> where V : I1, V : K, V : I2
+interface A4<K, V> where K : I1, K : I2, K : C, K : V, V : I2, V : I1
+
+fun <K, V> f1() where V : K, V : K {}
+fun <K, V, W> f2() where W : K, W : V {
+    fun <T> f3() where T : K, T : V {}
+    fun <T> f4() where T : K, T : K {}
+}
+fun <K, V, W> f3() where W : K, W : V, W : Any {}
diff --git a/compiler/testData/diagnostics/tests/generics/argumentsForT.fir.kt b/compiler/testData/diagnostics/tests/generics/argumentsForT.fir.kt
new file mode 100644
index 00000000000..ff8797c74e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/argumentsForT.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> foo(t: T<String, Int>) {}
+
+interface A
+class B<T: A>
+fun <T> foo1(t: T<B<String>>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/capturedParameters/captured.fir.kt b/compiler/testData/diagnostics/tests/generics/capturedParameters/captured.fir.kt
new file mode 100644
index 00000000000..354763be0a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/capturedParameters/captured.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class X {
+    abstract class Y<T : Any>
+
+    fun <T : Any> foo(y: Y<T>, t: T) {
+    }
+}
+
+
+fun testStar(y: X.Y<*>, t: Any) {
+    X().<!INAPPLICABLE_CANDIDATE!>foo<!>(y, t)
+}
+
+fun testOut(y: X.Y<out Any>, t: Any) {
+    X().<!INAPPLICABLE_CANDIDATE!>foo<!>(y, t)
+}
+
+fun testIn(y: X.Y<in Any>, t: Any) {
+    X().foo(y, t)
+}
+
+fun <T : Any> testWithParameter(y: X.Y<T>, t: Any) {
+    X().<!INAPPLICABLE_CANDIDATE!>foo<!>(y, t)
+}
+
+fun <T : Any> testWithCapturedParameter(y: X.Y<out T>, t: Any) {
+    X().<!INAPPLICABLE_CANDIDATE!>foo<!>(y, t)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/capturedParameters/innerLocalClass.fir.kt b/compiler/testData/diagnostics/tests/generics/capturedParameters/innerLocalClass.fir.kt
new file mode 100644
index 00000000000..9db00cd330e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/capturedParameters/innerLocalClass.fir.kt
@@ -0,0 +1,35 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// NI_EXPECTED_FILE
+private class Outer<E> {
+    private inner class Inner<out F> {
+        private fun <G> foo() = {
+            fun baz() = {
+                class Local {
+                    val e: E = magic()
+                    val f: F = magic()
+                    val g: G = magic()
+                }
+                Local()
+            }
+            baz()()
+        }
+
+        private var doubleCharSequenceInt = Outer<Double>().Inner<CharSequence>().foo<Int>()()
+        private var doubleStringNumber = Outer<Double>().Inner<String>().foo<Number>()()
+        private var doubleStringInt = Outer<Double>().Inner<String>().foo<Int>()()
+
+        private fun bar() {
+            doubleCharSequenceInt = doubleStringNumber
+            doubleCharSequenceInt = doubleStringInt
+
+            doubleStringInt = Outer<Double>().Inner<String>().foo<Int>()()
+
+            doubleStringInt.e.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Double>() }
+            doubleStringInt.f.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+            doubleStringInt.g.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+        }
+    }
+}
+
+fun <T> magic(): T = null!!
diff --git a/compiler/testData/diagnostics/tests/generics/capturedParameters/localClass.fir.kt b/compiler/testData/diagnostics/tests/generics/capturedParameters/localClass.fir.kt
new file mode 100644
index 00000000000..6a62c440362
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/capturedParameters/localClass.fir.kt
@@ -0,0 +1,25 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+fun <T> magic(): T = null!!
+
+class Q {
+    private fun <E> foo() = {
+        class C {
+            val prop: E = magic()
+        }
+        C()
+    }
+
+    private var x = foo<CharSequence>()()
+    private var y = foo<String>()()
+
+    fun bar() {
+        x = y
+        x = foo<CharSequence>()()
+        y = foo<String>()()
+
+        x.prop.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><CharSequence>() }
+        y.prop.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/capturedParameters/localWithTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/generics/capturedParameters/localWithTypeParameter.fir.kt
new file mode 100644
index 00000000000..034d17b6ce0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/capturedParameters/localWithTypeParameter.fir.kt
@@ -0,0 +1,22 @@
+// !CHECK_TYPE
+
+fun <T> magic(): T = null!!
+
+class Q {
+    private fun <E, F> foo() = {
+        class C<G> {
+            val e: E = magic()
+            val f: F = magic()
+            val g: G = magic()
+        }
+        C<F>()
+    }
+
+    private var x = foo<CharSequence, Number>()()
+
+    fun bar() {
+        x.e.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><CharSequence>() }
+        x.f.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Number>() }
+        x.g.checkType { _<Number>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/capturedParameters/objectLiteral.fir.kt b/compiler/testData/diagnostics/tests/generics/capturedParameters/objectLiteral.fir.kt
new file mode 100644
index 00000000000..6443c348009
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/capturedParameters/objectLiteral.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+fun <T> magic(): T = null!!
+
+class Q {
+    private fun <E> foo() =
+        object {
+            val prop: E = magic()
+        }
+
+    private var x = foo<CharSequence>()
+    private var y = foo<String>()
+
+    fun bar() {
+        x = y
+        x = foo<CharSequence>()
+        y = foo<String>()
+
+        x.prop.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><CharSequence>() }
+        y.prop.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt b/compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt
new file mode 100644
index 00000000000..7b382fd4076
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt
@@ -0,0 +1,37 @@
+fun <E> foo(x: Any, y: Any) : Any {
+    class C
+    // without E?
+    if(x is C) {
+        return x
+    }
+
+    if (1 == 2) {
+        x as C
+    }
+
+    if (2 == 3) {
+        x as? C
+    }
+
+    class Outer<F> {
+        inner class Inner
+    }
+
+    // bare type
+    if (y is Outer.Inner) {
+        return y
+    }
+
+    y as Outer<*>.Inner
+
+    return C()
+}
+
+fun noTypeParameters(x: Any) : Any {
+    class C
+    if(x is C) {
+        return x
+    }
+
+    return C()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/commonSupertypeContravariant.fir.kt b/compiler/testData/diagnostics/tests/generics/commonSupertypeContravariant.fir.kt
new file mode 100644
index 00000000000..4108d6dc3e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/commonSupertypeContravariant.fir.kt
@@ -0,0 +1,10 @@
+// NI_EXPECTED_FILE
+
+interface In<in E>
+
+class En<T> : In<T>
+class A : In<A>
+fun <T> select(x: T, y: T): T = x ?: y
+
+// Return type should be In<*> nor In<out Any?>
+fun foobar(e: En<*>) = select(A(), e)
diff --git a/compiler/testData/diagnostics/tests/generics/commonSupertypeContravariant2.fir.kt b/compiler/testData/diagnostics/tests/generics/commonSupertypeContravariant2.fir.kt
new file mode 100644
index 00000000000..89a3999ae58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/commonSupertypeContravariant2.fir.kt
@@ -0,0 +1,9 @@
+// NI_EXPECTED_FILE
+
+interface In<in E>
+class A : In<A>
+class B : In<B>
+fun <T> select(x: T, y: T) = x ?: y
+
+// Return type should be In<*> nor In<out Any?>
+fun foobar(a: A, b: B) = select(a, b)
diff --git a/compiler/testData/diagnostics/tests/generics/cyclicBounds/functions.fir.kt b/compiler/testData/diagnostics/tests/generics/cyclicBounds/functions.fir.kt
new file mode 100644
index 00000000000..e51939427e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/cyclicBounds/functions.fir.kt
@@ -0,0 +1,7 @@
+fun <T : F?, F : T?> foo1() {}
+
+fun <T : F?, F : E, E : F?> foo2() {}
+
+fun <T, F> foo3() where T : F?, F : T {}
+
+fun <T, F, E> foo4() where T : F?, F : E, E : F? {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/cyclicBounds/inClass.fir.kt b/compiler/testData/diagnostics/tests/generics/cyclicBounds/inClass.fir.kt
new file mode 100644
index 00000000000..aa08e862771
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/cyclicBounds/inClass.fir.kt
@@ -0,0 +1,7 @@
+class A1<T : F?, F : T?>
+
+class A2<T : F?, F : E, E : F?>
+
+class A3<T, F> where T : F?, F : T?
+
+class A4<T, F, E> where T : F?, F : E, E : F
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/doNotCaptureSupertype.fir.kt b/compiler/testData/diagnostics/tests/generics/doNotCaptureSupertype.fir.kt
new file mode 100644
index 00000000000..8c96719d74b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/doNotCaptureSupertype.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+// SKIP_TXT
+fun test(b: S) {
+    b.collect(toList()) checkType { <!UNRESOLVED_REFERENCE!>_<!><Inv<String>>() }
+}
+
+interface S {
+    fun <R> collect(collector: C<in String, R>): R
+}
+
+class C<X, Y>
+
+fun <T> toList(): C<T, Inv<T>> = null!!
+
+class Inv<Q>
diff --git a/compiler/testData/diagnostics/tests/generics/finalUpperBoundWithOverride.fir.kt b/compiler/testData/diagnostics/tests/generics/finalUpperBoundWithOverride.fir.kt
new file mode 100644
index 00000000000..425e4ecb019
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/finalUpperBoundWithOverride.fir.kt
@@ -0,0 +1,97 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+// Issues: KT-25105
+
+class Message1
+class Task<T>
+object Message2
+enum class Message3
+data class Message4(val x: Int)
+
+sealed class Message5<T> {
+    open fun <A : T> execute() {}
+}
+
+interface Manager<T> {
+    fun <A : T> execute1(task: Task<A>) {}
+    fun <T : Int> execute2(task: T) {}
+    fun <T : Message2> execute3() {}
+    fun <A : T> execute4() {}
+    fun <A : T> execute5() {}
+    val <A : T> A.x get() = 10
+    var <A : T> A.y
+        get() = 10
+        set(value) {}
+}
+
+object MessageManager1 : Manager<Message1> {
+    override fun <T : Message1> execute1(task: Task<T>) {}
+    override fun <T : Int> execute2(task: T) {}
+    override fun <T : Message2> execute3() {}
+}
+
+object MessageManager2 : Manager<Message3> {
+    override fun <T : Message3> execute4() {}
+}
+
+object MessageManager3 : Manager<Message4> {
+    override fun <T : Message4> execute5() {}
+}
+
+class MessageManager4 : Manager<Message1> {
+    override fun <T : Message1> execute1(task: Task<T>) {}
+    override fun <T : Int> execute2(task: T) {}
+    override fun <T : Message2> execute3() {}
+}
+
+class MessageManager5 : Manager<Message3> {
+    override fun <T : Message3> execute4() {}
+}
+
+class MessageManager6 : Manager<Message4> {
+    override fun <T : Message4> execute5() {}
+}
+
+interface MessageManager7 : Manager<Message4> {
+    override fun <T : Message4> execute5() {}
+}
+
+interface MessageManager8 : Manager<Message1> {
+    override fun <T : Message1> execute1(task: Task<T>) {}
+    override fun <T : Int> execute2(task: T) {}
+    override fun <T : Message2> execute3() {}
+}
+
+interface MessageManager9 : Manager<Message3> {
+    override fun <T : Message3> execute4() {}
+}
+
+object MessageManager10 : Message5<Int>() {
+    override fun <T : Int> execute() {}
+}
+
+class MessageManager11<A> : Message5<Message5<A>>() {
+    override fun <T : Message5<A>> execute() {}
+}
+
+data class MessageManager12(val x: Int) : Message5<Message2>() {
+    override fun <T : Message2> execute() {}
+}
+
+sealed class MessageManager13<A> : Message5<A>() {
+    override fun <T : A> execute() {}
+}
+
+class MessageManager14 : Manager<Message2> {
+    override val <T : Message2> T.x get() = 10
+    override var <T : Message2> T.y
+        get() = 10
+        set(value) {}
+}
+
+object MessageManager15 : Manager<Int> {
+    override val <T : Int> T.x get() = 10
+    override var <T : Int> T.y
+        get() = 10
+        set(value) {}
+}
diff --git a/compiler/testData/diagnostics/tests/generics/finalUpperBoundWithoutOverride.fir.kt b/compiler/testData/diagnostics/tests/generics/finalUpperBoundWithoutOverride.fir.kt
new file mode 100644
index 00000000000..e78300647c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/finalUpperBoundWithoutOverride.fir.kt
@@ -0,0 +1,82 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+// Issues: KT-25105
+
+class Message1
+class Task<T>
+object Message2
+enum class Message3
+data class Message4(val x: Int)
+interface Manager<T> {}
+
+object MessageManager1 : Manager<Message1> {
+    fun <T : Message1> execute1(task: Task<T>) {}
+    fun <T : Int> execute2(task: T) {}
+    fun <T : Message2> execute3() {}
+}
+
+object MessageManager2 : Manager<Message3> {
+    fun <T : Message3> execute4() {}
+}
+
+object MessageManager3 : Manager<Message4> {
+    fun <T : Message4> execute5() {}
+}
+
+class MessageManager4 : Manager<Message1> {
+    fun <T : Message1> execute1(task: Task<T>) {}
+    fun <T : Int> execute2(task: T) {}
+    fun <T : Message2> execute3() {}
+}
+
+class MessageManager5 : Manager<Message3> {
+    fun <T : Message3> execute4() {}
+}
+
+class MessageManager6 : Manager<Message4> {
+    fun <T : Message4> execute5() {}
+}
+
+interface MessageManager7 : Manager<Message4> {
+    fun <T : Message4> execute5() {}
+}
+
+interface MessageManager8 : Manager<Message1> {
+    fun <T : Message1> execute1(task: Task<T>) {}
+    fun <T : Int> execute2(task: T) {}
+    fun <T : Message2> execute3() {}
+}
+
+interface MessageManager9 : Manager<Message3> {
+    fun <T : Message3> execute4() {}
+}
+
+object MessageManager10 : Message5<Int>() {
+    fun <T : Int> execute() {}
+}
+
+class MessageManager11<A> : Message5<Message5<A>>() {
+    fun <T : Message5<A>> execute() {}
+}
+
+data class MessageManager12(val x: Int) : Message5<Message2>() {
+    fun <T : Message2> execute() {}
+}
+
+sealed class MessageManager13<A> : Message5<A>() {
+    fun <T : A> execute() {}
+}
+
+class MessageManager14 : Manager<Message2> {
+    val <T : Message2> T.x get() = 10
+    var <T : Message2> T.y
+        get() = 10
+        set(value) {}
+}
+
+object MessageManager15 : Manager<Int> {
+    val <T : Int> T.x get() = 10
+    var <T : Int> T.y
+        get() = 10
+        set(value) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/genericsInType.fir.kt b/compiler/testData/diagnostics/tests/generics/genericsInType.fir.kt
new file mode 100644
index 00000000000..176fd4ff604
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/genericsInType.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+
+class Foo<T> {
+    class Bar<X> {
+        class Baz {
+
+        }
+    }
+}
+
+fun <T> a() {}
+
+fun test() {
+    Foo::class
+    Foo.Bar::class
+    Foo.Bar.Baz::class
+
+    a<Foo.Bar<String>>()
+    a<Foo.Bar.Baz>()
+
+    Foo<String>.Bar::class
+    Foo<String>.Bar.Baz::class
+
+    a<Foo<String>.Bar>()
+    a<Foo<String>.Bar.Baz>()
+
+    a<Foo.Bar<Int>>()
+    a<Foo.Bar<Int>.Baz>()
+}
+
+fun <T: Foo<String.Bar>> x() {}
+fun Foo<String>.Bar.ext() {}
+
+fun ex1(a: Foo<String>.Bar<String>): Foo<String>.Bar<String> {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/bareTypes.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/bareTypes.fir.kt
new file mode 100644
index 00000000000..b88ad364875
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/bareTypes.fir.kt
@@ -0,0 +1,20 @@
+class Outer<E> {
+    inner class Inner<F, G> {
+        inner abstract class Inner2Base
+        inner class Inner2 : Inner2Base()
+
+        inner abstract class Inner3Base<B>
+        inner class Inner3<H> : Inner3Base<H>()
+    }
+
+    fun foo(x: Outer<*>.Inner<*, *>.Inner2Base) {
+        if (x is Inner.Inner2) return
+    }
+}
+
+fun bare(x: Outer<*>.Inner<*, *>.Inner2Base, y: Outer<*>.Inner<*, *>.Inner3Base<Int>) {
+    if (x is Outer.Inner.Inner2) return
+    if (y is Outer.Inner.Inner3) return
+    if (y is Outer<String>.Inner.Inner3) return
+    if (y is Outer.Inner<String, Int>.Inner3<Double>) return
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/bareTypesComplex.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/bareTypesComplex.fir.kt
new file mode 100644
index 00000000000..0bb4850fb9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/bareTypesComplex.fir.kt
@@ -0,0 +1,14 @@
+open class SuperOuter<E> {
+    inner open class SuperInner<F>
+}
+
+class DerivedOuter<G> : SuperOuter<G>() {
+    inner class DerivedInner<H> : SuperOuter<G>.SuperInner<H>()
+}
+
+fun bare(x: SuperOuter<*>.SuperInner<*>, y: Any?) {
+    if (x is SuperOuter.SuperInner) return
+    if (y is SuperOuter.SuperInner) {
+        return
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/checkBoundsOuter.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/checkBoundsOuter.fir.kt
new file mode 100644
index 00000000000..f273fb31857
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/checkBoundsOuter.fir.kt
@@ -0,0 +1,5 @@
+class Outer<E : Any> {
+    inner class Inner<F, G>
+}
+
+val x: Outer<String?>.Inner<String, Int> = null!!
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromCompanionObject_after.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromCompanionObject_after.fir.kt
new file mode 100644
index 00000000000..dcc376a304d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromCompanionObject_after.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+open class Outer<E> {
+    inner class Inner<F>
+
+}
+
+class Derived : Outer<String>() {
+    // Inner<Int> here means Outer<String>.Inner<Int>
+    fun foo(x: Inner<Int>) {}
+}
+
+class A {
+    companion object : Outer<String>()
+
+    // Does not work, could be Outer<String>.Inner<Int>
+    // TODO: Should work?
+    fun foo(x: Inner<Int>) {
+        // Inner<Char>() call use companion as implicit receiver
+        val y: Outer<String>.Inner<Char> = Inner<Char>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromCompanionObject_before.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromCompanionObject_before.fir.kt
new file mode 100644
index 00000000000..6a546fe3d55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromCompanionObject_before.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+open class Outer<E> {
+    inner class Inner<F>
+
+}
+
+class Derived : Outer<String>() {
+    // Inner<Int> here means Outer<String>.Inner<Int>
+    fun foo(x: Inner<Int>) {}
+}
+
+class A {
+    companion object : Outer<String>()
+
+    // Does not work, could be Outer<String>.Inner<Int>
+    // TODO: Should work?
+    fun foo(x: Inner<Int>) {
+        // Inner<Char>() call use companion as implicit receiver
+        val y: Outer<String>.Inner<Char> = Inner<Char>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromOuterClassInObjectLiteral.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromOuterClassInObjectLiteral.fir.kt
new file mode 100644
index 00000000000..22600b275a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromOuterClassInObjectLiteral.fir.kt
@@ -0,0 +1,15 @@
+class A<T> {
+    fun foo() {
+        val q = object {
+            open inner class B
+            inner class C : B()
+
+            // No WRONG_NUMBER_OF_TYPE_ARGUMENTS should be reported on these types
+            val x: B = B()
+            val y: C = C()
+        }
+
+        q.x
+        q.y
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClasses.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClasses.fir.kt
new file mode 100644
index 00000000000..671cdf3cf64
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClasses.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+// !CHECK_TYPE
+open class Outer<X, Y> {
+    inner class Inner<Z>
+    typealias Alias<W> = Map<W, X>
+}
+
+class Derived : Outer<String, Int>() {
+    fun foo(): Inner<Char> = null!!
+    fun baz(): Alias<Char> = null!!
+}
+
+
+class A : Outer<Double, Short>() {
+    class B : Outer<Float, Long>() {
+        fun bar(): Inner<String> = null!!
+        fun x(): Alias<String> = null!!
+    }
+}
+
+fun foo() {
+    Derived().foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><Outer<String, Int>.Inner<Char>>() }
+    Derived().baz() checkType { <!UNRESOLVED_REFERENCE!>_<!><Map<Char, String>>() }
+    A.B().bar() checkType { <!UNRESOLVED_REFERENCE!>_<!><Outer<Float, Long>.Inner<String>>() }
+    A.B().x() checkType { <!UNRESOLVED_REFERENCE!>_<!><Map<String, Float>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesLocal.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesLocal.fir.kt
new file mode 100644
index 00000000000..95c97c0dfd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesLocal.fir.kt
@@ -0,0 +1,55 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER -TOPLEVEL_TYPEALIASES_ONLY
+
+class A<R1, R2, R3, R4>
+
+private fun <E> foobar() = {
+    open class LocalOuter<X, Y> {
+        inner class LocalInner<Z> {
+            fun a() = A<E, X, Y, Z>()
+        }
+
+        typealias LocalAlias<W> = A<E, X, Y, W>
+    }
+
+    class Derived : LocalOuter<Double, Short>() {
+        fun foo(): LocalInner<Long> = null!!
+        fun bar(): LocalAlias<Char> = null!!
+    }
+
+    Derived()
+}
+
+private fun noParameters() = {
+    open class LocalOuter2<X, Y> {
+        inner class LocalInner2<Z> {
+            fun a() = A<Any, X, Y, Z>()
+        }
+
+        typealias LocalAlias2<W> = A<Any, X, Y, W>
+    }
+
+    class Derived2 : LocalOuter2<Double, Short>() {
+        fun foo(): LocalInner2<Long> = null!!
+        fun bar(): LocalAlias2<Char> = null!!
+    }
+
+    Derived2()
+}
+
+fun test() {
+    var x = foobar<String>()
+    x = foobar<String>()
+
+    x().foo().a() checkType { <!UNRESOLVED_REFERENCE!>_<!><A<String, Double, Short, Long>>() }
+    x().bar() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><A<String, Double, Short, Char>>() }
+
+    x = foobar<Int>()
+
+    var y = noParameters()
+    y = noParameters()
+
+    y().foo().a() checkType { <!UNRESOLVED_REFERENCE!>_<!><A<Any, Double, Short, Long>>() }
+    y().bar() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><A<Any, Double, Short, Char>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesLocalInsideInner.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesLocalInsideInner.fir.kt
new file mode 100644
index 00000000000..43541fe539a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesLocalInsideInner.fir.kt
@@ -0,0 +1,59 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER -TOPLEVEL_TYPEALIASES_ONLY
+
+class A<R1, R2, R3, R4, R5, R6>
+
+class Outer<T> {
+    inner class Inner<F> {
+        private fun <E> foobar() = {
+            open class LocalOuter<X, Y> {
+                inner class LocalInner<Z> {
+                    fun a() = A<T, F, E, X, Y, Z>()
+                }
+
+                typealias LocalAlias<W> = A<T, F, E, X, Y, W>
+            }
+
+            class Derived : LocalOuter<Double, Short>() {
+                fun foo(): LocalInner<Long> = null!!
+                fun bar(): LocalAlias<Char> = null!!
+            }
+
+            Derived()
+        }
+
+        private fun noParameters() = {
+            open class LocalOuter2<X, Y> {
+                inner class LocalInner2<Z> {
+                    fun a() = A<T, F, Any, X, Y, Z>()
+                }
+
+                typealias LocalAlias2<W> = A<T, F, Any, X, Y, W>
+            }
+
+            class Derived2 : LocalOuter2<Double, Short>() {
+                fun foo(): LocalInner2<Long> = null!!
+                fun bar(): LocalAlias2<Char> = null!!
+            }
+            Derived2()
+        }
+
+        fun test(z: Outer<String>.Inner<F>) {
+            var x = foobar<String>()
+            x = foobar<String>()
+
+            x().foo().a() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><A<T, F, String, Double, Short, Long>>() }
+            x().bar() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!INAPPLICABLE_CANDIDATE!>_<!><A<T, F, String, Double, Short, Char>>() }
+
+            x = foobar<Int>()
+            x = z.foobar<String>()
+
+            var y = noParameters()
+            y = noParameters()
+
+            y().foo().a() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><A<T, F, Any, Double, Short, Long>>() }
+            y().bar() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!INAPPLICABLE_CANDIDATE!>_<!><A<T, F, Any, Double, Short, Char>>() }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesTransitive.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesTransitive.fir.kt
new file mode 100644
index 00000000000..0086dbfa03e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/fromSuperClassesTransitive.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+// !CHECK_TYPE
+open class Outer<X, Y> {
+    inner class Inner<Z>
+    typealias Alias<W> = Map<W, X>
+}
+
+open class BaseDerived1<E, F> : Outer<F, E>()
+open class BaseDerived2<X> : BaseDerived1<String, X>()
+
+class Derived : BaseDerived2<Int>() {
+    fun foo(): Inner<Char> = null!!
+    fun baz(): Alias<Char> = null!!
+}
+
+fun foo() {
+    Derived().foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><Outer<Int, String>.Inner<Char>>() }
+    Derived().baz() checkType { <!UNRESOLVED_REFERENCE!>_<!><Map<Char, Int>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/inStaticScope.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/inStaticScope.fir.kt
new file mode 100644
index 00000000000..44a567abaa0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/inStaticScope.fir.kt
@@ -0,0 +1,7 @@
+interface Inv<X>
+class Outer<E> {
+    inner class Inner
+
+    class Nested : Inv<Inner>
+    object Obj : Inv<Inner>
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/secondLevelDepth.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/secondLevelDepth.fir.kt
new file mode 100644
index 00000000000..e5f856332b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/implicitArguments/secondLevelDepth.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+open class Outer<E> {
+    inner open class Inner<F> {
+        inner class Inner2<D> {
+
+        }
+    }
+}
+
+class DerivedOuter : Outer<String>() {
+    inner class DerivedInner : Inner<Int>() {
+        fun foo(): Inner2<Char> = null!!
+    }
+}
+
+fun foo() {
+    DerivedOuter().DerivedInner().foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><Outer<String>.Inner<Int>.Inner2<Char>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/importedInner.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/importedInner.fir.kt
new file mode 100644
index 00000000000..5246f574368
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/importedInner.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+import Outer.Inner
+
+
+class Outer<E> {
+    inner class Inner
+
+    fun foo() {
+        class E
+        val x: Inner = Inner()
+    }
+
+    class Nested {
+        fun bar(x: Inner) {}
+    }
+}
+
+class E
+
+fun bar(x: Inner) {}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/innerSuperCall.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/innerSuperCall.fir.kt
new file mode 100644
index 00000000000..64d4139d014
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/innerSuperCall.fir.kt
@@ -0,0 +1,9 @@
+open class Super<T> {
+    inner open class Inner {
+    }
+}
+
+class Sub : Super<String>() {
+    // TODO: it would be nice to have a possibility to omit explicit type argument in supertype
+    inner class SubInner : Super<String>.Inner() {}
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/innerSuperCallSecondary.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/innerSuperCallSecondary.fir.kt
new file mode 100644
index 00000000000..9d96d736e46
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/innerSuperCallSecondary.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class Super<T> {
+    inner open class Inner {
+    }
+}
+
+class Sub : Super<String>() {
+    inner class SubInner : Super<String>.Inner {
+        constructor()
+        constructor(x: Int) : super() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/innerTP.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/innerTP.fir.kt
new file mode 100644
index 00000000000..fc90a12c068
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/innerTP.fir.kt
@@ -0,0 +1,42 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class Outer<E> {
+    inner class Inner<F> {
+        fun foo() = this
+        fun baz(): Inner<String> = null!!
+    }
+
+    fun innerFactory(): Outer<E>.Inner<String> = null!!
+
+    fun bar() = Inner<E>()
+    fun set(inner: Inner<out E>) {}
+
+    fun inside() {
+        innerFactory().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Inner<String>>() }
+    }
+}
+
+fun factoryString(): Outer<String>.Inner<String> = null!!
+
+fun <T, Y> infer(x: T, y: Y): Outer<T>.Inner<Y> = null!!
+val inferred = infer("", 1)
+
+fun main() {
+    val outer = Outer<String>()
+
+    checkSubtype<Outer<String>.Inner<String>>(outer.bar())
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Outer<String>.Inner<Int>>(outer.Inner<Int>())
+    checkSubtype<Outer<*>.Inner<*>>(outer.bar())
+    checkSubtype<Outer<*>.Inner<*>>(outer.Inner<Int>())
+
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Outer<CharSequence>.Inner<CharSequence>>(outer.bar())
+    checkSubtype<Outer<CharSequence>.Inner<CharSequence>>(outer.Inner())
+
+    outer.set(outer.bar())
+    outer.set(outer.Inner())
+
+    val x: Outer<String>.Inner<String> = factoryString()
+    outer.set(x)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/innerUncheckedCast.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/innerUncheckedCast.fir.kt
new file mode 100644
index 00000000000..f954a3c35fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/innerUncheckedCast.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+class Outer<E> {
+    inner open class InnerBase<F>
+    inner class Inner<H> : InnerBase<H>() {
+        val prop: E = null!!
+    }
+
+    fun foo(x: InnerBase<String>, y: Any?, z: Outer<*>.InnerBase<String>) {
+        if (x is Inner) {
+            x.prop.checkType { _<E>() }
+        }
+
+        if (y is Inner) return
+
+        if (z is Inner) {
+            z.prop.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Any?>() }
+            return
+        }
+
+        if (y is Outer<*>.Inner<*>) {
+            y.prop.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Any?>() }
+        }
+    }
+
+    fun bar(x: InnerBase<String>, y: Any?, z: Outer<*>.InnerBase<String>) {
+        x as Inner
+        y as Inner
+        z as Inner
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/innerVariance.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/innerVariance.fir.kt
new file mode 100644
index 00000000000..976d5e03690
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/innerVariance.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class Outer<out E, in F> {
+    inner class Inner {
+        fun unsafe1(x: E) {}
+        fun unsafe2(x: Collection<E?>) {}
+        fun unsafe3(): F? = null
+        fun unsafe4(): Collection<F>? = null
+    }
+
+    // Should be errors
+    // Refinement of variance checker is needed
+    fun foo(x: Inner) {}
+    fun bar(): Inner? = null
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/iterator.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/iterator.fir.kt
new file mode 100644
index 00000000000..f1a49b86889
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/iterator.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER -UNUSED_VARIABLE
+// JAVAC_EXPECTED_FILE
+import java.util.*
+
+class A<T> : AbstractCollection<T>() {
+    override fun iterator(): MyIt = MyIt()
+
+    override val size: Int
+        get() = 1
+
+    inner class MyIt : MutableIterator<T> {
+        override fun next(): T {
+            throw UnsupportedOperationException()
+        }
+
+        override fun hasNext(): Boolean {
+            throw UnsupportedOperationException()
+        }
+
+        override fun remove() {
+            throw UnsupportedOperationException()
+        }
+    }
+}
+
+fun <E> commonSupertype(x: E, y: E): E = x
+
+fun foo() {
+    var myIt = A<String>().iterator()
+    myIt = A<Int>().iterator()
+
+    val csIt: Iterator<CharSequence> = A<String>().iterator()
+
+    commonSupertype(A<String>().iterator(), A<Int>().iterator()).checkType { _<A<out Any>.MyIt>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/j+k.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/j+k.fir.kt
new file mode 100644
index 00000000000..464f3290453
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/j+k.fir.kt
@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+// FILE: Outer.java
+
+public class Outer<E> {
+    public class Inner<F> {
+        E foo() {}
+        F bar() {}
+
+        Outer<E> outer() {}
+    }
+
+    Inner<E> baz() { }
+    void set(Inner<String> x) {}
+}
+
+// FILE: main.kt
+
+fun main() {
+    var outerStr: Outer<String> = Outer()
+    outerStr.baz().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Outer<String>.Inner<String>>() }
+
+    val strInt: Outer<String>.Inner<Int> = outerStr.Inner()
+
+    strInt.foo().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    strInt.bar().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+    strInt.outer().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Outer<String>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/j+k_complex.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/j+k_complex.fir.kt
new file mode 100644
index 00000000000..22f0faaa562
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/j+k_complex.fir.kt
@@ -0,0 +1,35 @@
+// !CHECK_TYPE
+// FILE: BaseOuter.java
+// See KT-10285
+public class BaseOuter<H> {
+    abstract public class BaseInner<E, F> {
+        public H foo1() {
+            return null;
+        }
+
+        public E foo2() {
+            return null;
+        }
+
+        public F foo3() {
+            return null;
+        }
+    }
+}
+
+// FILE: Outer.java
+public class Outer<H> extends BaseOuter<H> {
+    public BaseInner<Double, String> bar() { return null; }
+    public class Inner extends BaseOuter<H>.BaseInner<Double, String> {}
+}
+
+// FILE: main.kt
+fun foo(x1: Outer<Int>, x2: Outer<Int>.Inner) {
+    x1.bar().foo1().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+    x1.bar().foo2().checkType { _<Double>() }
+    x1.bar().foo3().checkType { _<String>() }
+
+    x2.foo1().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+    x2.foo2().checkType { _<Double>() }
+    x2.foo3().checkType { _<String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/kt3357.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/kt3357.fir.kt
new file mode 100644
index 00000000000..795e8235a6c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/kt3357.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+open class Super<T> {
+    inner open class Inner {
+        open fun getOuter(): Super<T> = throw UnsupportedOperationException()
+    }
+}
+
+class Sub<T1>(): Super<T1>() {
+    inner class SubInner : Super<T1>.Inner() { // 'Inner' is unresolved
+        // Also, T1 is not resolved to anything, and not marked as resolved
+        init {
+            val x: Super<T1>.Inner = this // T1 is not resolved to anything
+        }
+
+        override fun getOuter(): Sub<T1> = throw UnsupportedOperationException()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/kt408.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/kt408.fir.kt
new file mode 100644
index 00000000000..02585cbc7cd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/kt408.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+interface T<E> {
+    fun f() : E = null!!
+}
+open class A<X>() {
+    inner class B() : T<X> {}
+}
+
+fun test() {
+    val a = A<Int>()
+    val b : A<Int>.B = a.B()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/kt6325.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/kt6325.fir.kt
new file mode 100644
index 00000000000..7a617258247
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/kt6325.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class Outer<T> {
+    inner class Inner<R> {
+        fun <S> newInner(): Inner<S> = Inner()
+        //type mismatch
+        fun <U, S> newOuterInner(): Outer<U>.Inner<S> = Outer<U>().Inner<S>()
+        //^ U here is not analyzed
+        fun foo(t: T, r: R) {}
+    }
+}
+
+fun test0() {
+    val inner: Outer<Int>.Inner<String> = Outer<Int>().Inner<String>()
+    Outer<Int>().Inner<String>().foo(1, "") // type mismatch on second argument
+}
+
+
+fun test1() {
+    Outer<Int>().Inner<String>().newOuterInner<Double, Boolean>().<!UNRESOLVED_REFERENCE!>foo<!>(1.0, true) // type mismatch on 1.0
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/outerArgumentsRequired.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/outerArgumentsRequired.fir.kt
new file mode 100644
index 00000000000..a26cddf1a78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/outerArgumentsRequired.fir.kt
@@ -0,0 +1,23 @@
+import A.B.D
+import A.B.C
+import A.B.D.Innermost
+
+class A<T> {
+    inner class B<F> {
+        inner class C<E>
+        inner class D {
+            inner class Innermost<X>
+        }
+    }
+
+    class Nested {
+        val x: B<String>? = null
+        val y: B<String>.C<String>? = null
+        val z: B<String>.D? = null
+
+        val c: C<Int>? = null
+        val d: D? = null
+
+        val innerMost: Innermost<String>? = null
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/parameterShadowing.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/parameterShadowing.fir.kt
new file mode 100644
index 00000000000..21286722014
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/parameterShadowing.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class Outer<E> {
+    inner class Inner<E> {
+        fun foo(): E = null!!
+        fun outerE() = baz()
+    }
+
+    fun baz(): E = null!!
+}
+
+fun main() {
+    val inner = Outer<String>().Inner<Int>()
+
+    inner.foo().checkType { _<Int>() }
+    inner.outerE().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/qualifiedOuter.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/qualifiedOuter.fir.kt
new file mode 100644
index 00000000000..0b3c53ddefe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/qualifiedOuter.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VALUE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+
+class Outer<T> {
+    inner class Inner
+    fun foo(x: Outer<String>.Inner, y: Outer.Inner, z: Inner) {
+        var inner = Inner()
+        x.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Inner>() }
+        x.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Outer<String>.Inner>() }
+        z.checkType { _<Inner>() }
+        z.checkType { _<Outer<T>.Inner>() }
+
+        inner = x
+    }
+
+    class Nested
+    fun bar(x: Outer.Nested) {
+        var nested = Nested()
+        nested = x
+
+        x.checkType { _<Nested>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/qualifiedTypesResolution.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/qualifiedTypesResolution.fir.kt
new file mode 100644
index 00000000000..b21c57691f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/qualifiedTypesResolution.fir.kt
@@ -0,0 +1,51 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+// FILE: test.kt
+
+package test
+
+class Outer<E> {
+    inner class Inner<F, G> {
+        inner class Inner2
+        inner class Inner3<H>
+    }
+
+    class Nested<I> {
+        inner class Inner4<K>
+    }
+
+    object Obj {
+        class Nested2<J> {
+            inner class Inner5<L>
+        }
+    }
+}
+
+// FILE: main.kt
+
+import test.*;
+
+class A
+class B
+class C
+class D
+
+fun ok1(): Outer<A>.Inner<B, C>.Inner2 = null!!
+fun ok2(): Outer<A>.Inner<B, C>.Inner2 = null!!
+fun ok22(): test.Outer<A>.Inner<B, C>.Inner3<D> = null!!
+fun ok3(): Outer.Nested<A>.Inner4<B> = null!!
+fun ok4(): Outer.Obj.Nested2<A>.Inner5<B> = null!!
+fun ok5(): test.Outer.Obj.Nested2<A>.Inner5<B> = null!!
+
+// All arguments are resolved
+fun errorTypeWithArguments(): Q<A>.W<B, C, D>.R.M = null!!
+
+fun error1(): Outer<A>.Inner<B>.Inner3<C, D> = null!!
+fun error2(): Outer<A>.Inner<B, C, D>.Inner2 = null!!
+fun error3(): Outer.Inner<A, B>.Inner3<C> = null!!
+
+fun error4(): Outer<A>.Nested<B>.Inner4<C> = null!!
+fun error5(): Outer<A>.Obj.Nested2<B>.Inner5<C> = null!!
+fun error6(): Outer.Obj<A>.Nested2<B>.Inner5<C> = null!!
+
+fun error7(): test<String>.Outer.Obj.Nested2<A>.Inner5<B> = null!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/simple.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/simple.fir.kt
new file mode 100644
index 00000000000..ed3d9809b04
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/simple.fir.kt
@@ -0,0 +1,36 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class Outer<E> {
+    inner class Inner {
+        fun foo() = this
+        fun baz(): Inner = this
+    }
+
+    fun bar() = Inner()
+
+    fun set(inner: Inner) {}
+}
+
+fun factoryString(): Outer<String>.Inner = null!!
+
+fun <T> infer(x: T): Outer<T>.Inner = null!!
+val inferred = infer("")
+
+fun main() {
+    val outer = Outer<String>()
+
+    checkSubtype<Outer<String>.Inner>(outer.bar())
+    checkSubtype<Outer<String>.Inner>(outer.Inner())
+    checkSubtype<Outer<*>.Inner>(outer.bar())
+    checkSubtype<Outer<*>.Inner>(outer.Inner())
+
+    checkSubtype<Outer<CharSequence>.Inner>(outer.bar())
+    checkSubtype<Outer<CharSequence>.Inner>(outer.Inner())
+
+    outer.set(outer.bar())
+    outer.set(outer.Inner())
+
+    val x: Outer<String>.Inner = factoryString()
+    outer.set(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/simpleIn.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/simpleIn.fir.kt
new file mode 100644
index 00000000000..e0180d525c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/simpleIn.fir.kt
@@ -0,0 +1,40 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class Outer<in E> {
+    inner class Inner {
+        fun foo() = this
+        fun baz(): Inner = this
+    }
+
+    fun bar() = Inner()
+
+    fun set(inner: Inner) {}
+}
+
+fun factoryString(): Outer<String>.Inner = null!!
+
+fun <T> infer(x: T): Outer<T>.Inner = null!!
+val inferred = infer("")
+
+fun main() {
+    val outer = Outer<CharSequence>()
+
+    checkSubtype<Outer<CharSequence>.Inner>(outer.bar())
+    checkSubtype<Outer<CharSequence>.Inner>(outer.Inner())
+    checkSubtype<Outer<*>.Inner>(outer.bar())
+    checkSubtype<Outer<*>.Inner>(outer.Inner())
+
+    checkSubtype<Outer<String>.Inner>(outer.bar())
+    checkSubtype<Outer<String>.Inner>(outer.Inner())
+
+    outer.set(outer.bar())
+    outer.set(outer.Inner())
+
+    val x: Outer<String>.Inner = factoryString()
+    outer.set(x)
+    val y: Outer<CharSequence>.Inner = infer<CharSequence>("")
+    outer.set(y)
+
+    outer.set(infer<Any>(""))
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/simpleOut.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/simpleOut.fir.kt
new file mode 100644
index 00000000000..e155df657c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/simpleOut.fir.kt
@@ -0,0 +1,37 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class Outer<out E> {
+    inner class Inner {
+        fun foo() = this
+        fun baz(): Inner = this
+    }
+
+    fun bar() = Inner()
+
+    // Should be unsafe variance error here
+    fun set(inner: Inner) {}
+}
+
+fun factoryString(): Outer<String>.Inner = null!!
+
+fun <T> infer(x: T): Outer<T>.Inner = null!!
+val inferred = infer("")
+
+fun main() {
+    val outer = Outer<String>()
+
+    checkSubtype<Outer<String>.Inner>(outer.bar())
+    checkSubtype<Outer<String>.Inner>(outer.Inner())
+    checkSubtype<Outer<*>.Inner>(outer.bar())
+    checkSubtype<Outer<*>.Inner>(outer.Inner())
+
+    checkSubtype<Outer<CharSequence>.Inner>(outer.bar())
+    checkSubtype<Outer<CharSequence>.Inner>(outer.Inner())
+
+    outer.set(outer.bar())
+    outer.set(outer.Inner())
+
+    val x: Outer<String>.Inner = factoryString()
+    outer.set(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/simpleOutUseSite.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/simpleOutUseSite.fir.kt
new file mode 100644
index 00000000000..b894c10f9f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/simpleOutUseSite.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class Outer<E> {
+    inner class Inner {
+        fun foo() = this
+        fun baz(): Inner = this
+    }
+
+    fun bar() = Inner()
+
+    fun set(inner: Inner) {}
+}
+
+fun factoryString(): Outer<String>.Inner = null!!
+
+fun <T> infer(x: T): Outer<T>.Inner = null!!
+val inferred = infer("")
+
+fun main() {
+    val outer: Outer<out String> = Outer<String>()
+
+    checkSubtype<Outer<out String>.Inner>(outer.bar())
+    checkSubtype<Outer<out String>.Inner>(outer.Inner())
+    checkSubtype<Outer<*>.Inner>(outer.bar())
+    checkSubtype<Outer<*>.Inner>(outer.Inner())
+
+    checkSubtype<Outer<out CharSequence>.Inner>(outer.bar())
+    checkSubtype<Outer<out CharSequence>.Inner>(outer.Inner())
+
+    outer.set(outer.bar())
+    outer.set(outer.Inner())
+
+    val x: Outer<String>.Inner = factoryString()
+    outer.set(x)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/innerClasses/substitutedMemberScope.fir.kt b/compiler/testData/diagnostics/tests/generics/innerClasses/substitutedMemberScope.fir.kt
new file mode 100644
index 00000000000..914dfb898c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/innerClasses/substitutedMemberScope.fir.kt
@@ -0,0 +1,49 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+
+class Outer<E> {
+    inner class Inner<F> {
+        fun instance() = this@Outer
+        fun foo(): E = null!!
+        fun bar(e: E, f: F) {}
+        fun baz(): F = null!!
+
+        fun act() {
+            foo().checkType { _<E>() }
+            outerE().checkType { _<E>() }
+            instance().checkType { _<Outer<E>>() }
+            instance().outerE().checkType { _<E>() }
+
+            bar(foo(), baz())
+            bar(outerE(), baz())
+            bar(instance().outerE(), baz())
+
+            <!INAPPLICABLE_CANDIDATE!>bar<!>(topLevel().Inner<E>().baz(), topLevel().Inner<E>().baz())
+            <!INAPPLICABLE_CANDIDATE!>bar<!>(topLevel().Inner<E>().foo(), topLevel().Inner<E>().baz())
+
+            setE(foo())
+        }
+    }
+
+    fun outerE(): E = null!!
+
+    fun setE(e: E) {}
+    fun setInner(inner: Inner<Int>) {}
+}
+
+fun topLevel(): Outer<String> = null!!
+
+fun foo() {
+    val strInt: Outer<String>.Inner<Int> = Outer<String>().Inner()
+
+    strInt.foo().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    strInt.baz().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+
+    strInt.instance().<!INAPPLICABLE_CANDIDATE!>setE<!>("")
+    strInt.instance().outerE().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+
+    strInt.instance().Inner<Double>().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Outer<String>.Inner<Double>>() }
+
+    Outer<String>().<!INAPPLICABLE_CANDIDATE!>setInner<!>(strInt)
+    Outer<CharSequence>().<!INAPPLICABLE_CANDIDATE!>setInner<!>(strInt)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/invalidArgumentsNumberInWhere.fir.kt b/compiler/testData/diagnostics/tests/generics/invalidArgumentsNumberInWhere.fir.kt
new file mode 100644
index 00000000000..4225780a004
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/invalidArgumentsNumberInWhere.fir.kt
@@ -0,0 +1,19 @@
+class A
+interface I0<T : A<Int>>
+interface I1<T> where T : A<Int>
+interface I2<T : A<Int>> where T : A<Int>
+
+fun <E : A<Int>> foo0() {}
+fun <E> foo1() where E : A<Int> {}
+fun <E : A<Int>> foo2() where E : A<Int> {}
+
+val <E : A<Int>> E.p1: Int
+        get() = 1
+val <E> E.p2: Int where E : A<Int>
+        get() = 1
+val <E : A<Int>> E.p3: Int where E : A<Int>
+        get() = 1
+
+// See KT-8200
+interface X
+public class EnumAttribute<T : X<T>>(val klass: Class<T>) where T : Enum<T>
diff --git a/compiler/testData/diagnostics/tests/generics/kt1575-Class.fir.kt b/compiler/testData/diagnostics/tests/generics/kt1575-Class.fir.kt
new file mode 100644
index 00000000000..87a3d632526
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/kt1575-Class.fir.kt
@@ -0,0 +1 @@
+class C<T : C<T>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/kt1575-Function.fir.kt b/compiler/testData/diagnostics/tests/generics/kt1575-Function.fir.kt
new file mode 100644
index 00000000000..58a6f6bc1fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/kt1575-Function.fir.kt
@@ -0,0 +1,2 @@
+class C<T>
+fun <T : C<T>> foo() {}
diff --git a/compiler/testData/diagnostics/tests/generics/kt30590.fir.kt b/compiler/testData/diagnostics/tests/generics/kt30590.fir.kt
new file mode 100644
index 00000000000..fc7f293f8c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/kt30590.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// NI_EXPECTED_FILE
+
+interface A
+fun <T: A, R: T> emptyStrangeMap(): Map<T, R> = TODO()
+fun test7() : Map<A, A> = emptyStrangeMap()
+
+fun test() = emptyStrangeMap()
diff --git a/compiler/testData/diagnostics/tests/generics/kt5508.fir.kt b/compiler/testData/diagnostics/tests/generics/kt5508.fir.kt
new file mode 100644
index 00000000000..f7b373f9128
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/kt5508.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// KT-5508 Stackoverflow in type substitution
+
+abstract class A<T> {
+    public abstract fun foo(x: T)
+    public abstract fun bar(x: T)
+
+    public inner abstract class B<S> : A<B<S>>() {
+        public inner class C<U> : B<C<U>>()
+        {
+            // Here B<C<U>> means A<A<A<T>.B<S>>.B<A<T>.B<S>.C<U>>>.B<A<A<T>.B<S>>.B<A<T>.B<S>.C<U>>.C<U>>
+            // while for being a correct override it should be A<A<T>.B<S>>.B<A<T>.B<S>.C<U>>
+            // It happens because at the beginning we search implicit arguments for an outer classes through supertypes
+            // See TypeResolver.computeImplicitOuterClassArguments for clarifications
+            override fun foo(x: B<C<U>>)  {
+                throw UnsupportedOperationException()
+            }
+
+            override fun bar(x: A<A<T>.B<S>>.B<A<T>.B<S>.C<U>>) {
+                throw UnsupportedOperationException()
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/kt9203.fir.kt b/compiler/testData/diagnostics/tests/generics/kt9203.fir.kt
new file mode 100644
index 00000000000..01d1f6f9ee0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/kt9203.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+import java.util.stream.Collectors
+import java.util.stream.IntStream
+
+fun main() {
+    val xs = IntStream.range(0, 10).mapToObj { it.toString() }
+            .<!INAPPLICABLE_CANDIDATE!>collect<!>(Collectors.toList())
+    <!UNRESOLVED_REFERENCE!>xs[0]<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/kt9203_1.fir.kt b/compiler/testData/diagnostics/tests/generics/kt9203_1.fir.kt
new file mode 100644
index 00000000000..369d4f017d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/kt9203_1.fir.kt
@@ -0,0 +1,18 @@
+public interface Collector<T, R>
+
+class A<out T> {
+    fun foo(): T = null!!
+}
+
+public fun <T> toList(): Collector<T, A<T>> = null!!
+
+interface Stream<T> {
+    public fun <R> collect(collector: Collector<in T, R>): R
+}
+fun stream(): Stream<String> = null!!
+
+fun main() {
+    val stream: Stream<String> = stream()
+    val xs = stream.collect(toList())
+    xs.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/kt9985.fir.kt b/compiler/testData/diagnostics/tests/generics/kt9985.fir.kt
new file mode 100644
index 00000000000..6af3f78e7e7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/kt9985.fir.kt
@@ -0,0 +1,46 @@
+// !CHECK_TYPE
+// Incorrect "type mismatch" error for generic extension safe call (required not-null, found nullable)
+
+// FILE: B.java
+
+public class B<T> {
+    public String gav() {
+        return "";
+    }
+
+    public static <T> B<T> create() {
+        return new B();
+    }
+}
+
+// FILE: A.kt
+
+class A<T> {
+    fun gav() = ""
+}
+fun <R> foo(x: R) = x
+fun <T> A<T>.bar() = ""
+fun <T> B<T>.bar() = ""
+
+fun foo(l: A<String>?) {
+    // No errors should be here
+    foo(l?.bar()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    foo(l?.gav()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    if (l != null) {
+        foo(l?.bar()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        foo(l?.gav()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+}
+
+fun fooNotNull(l: A<String>) {
+    // No errors should be here
+    foo(l?.bar()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    foo(l?.gav()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
+
+fun bar() {
+    val l = B.create<String>()
+    foo(l?.bar()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    foo(l?.gav()) checkType { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+}
+
diff --git a/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/conflictingReturnType.fir.kt b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/conflictingReturnType.fir.kt
new file mode 100644
index 00000000000..21c273e3c1b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/conflictingReturnType.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+interface A {
+    fun foo(): CharSequence
+}
+
+interface B {
+    fun foo(): String?
+}
+
+fun <T> test(x: T) where T : B, T : A {
+    x.<!AMBIGUITY!>foo<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/flexibleTypes.fir.kt b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/flexibleTypes.fir.kt
new file mode 100644
index 00000000000..48dbfbe7bbc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/flexibleTypes.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+// FILE: A.java
+public interface A {
+    String foo();
+}
+
+// FILE: main.kt
+
+interface B {
+    fun foo(): String?
+}
+
+interface C {
+    fun foo(): String
+}
+
+fun <T> test(x: T) where T : B, T : A, T : C {
+    x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/mostSpecific.fir.kt b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/mostSpecific.fir.kt
new file mode 100644
index 00000000000..60fb0f2154b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/mostSpecific.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+interface A {
+    fun foo(): CharSequence?
+}
+
+interface B {
+    fun foo(): String
+}
+
+fun <T> test(x: T) where T : B, T : A {
+    x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/properties.fir.kt b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/properties.fir.kt
new file mode 100644
index 00000000000..24de5e835b9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/properties.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+
+interface A {
+    val foo: Any?
+}
+
+interface C: A {
+    override val foo: String?
+}
+interface B: A {
+    override var foo: String
+}
+
+fun <T> test(a: T) where T : B, T : C {
+    a.<!AMBIGUITY!>foo<!> = ""
+    a.<!AMBIGUITY!>foo<!> = null
+
+    a.<!AMBIGUITY!>foo<!>.<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/propertiesConflict.fir.kt b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/propertiesConflict.fir.kt
new file mode 100644
index 00000000000..a026254004d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/propertiesConflict.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+
+interface A {
+    val foo: Any?
+}
+
+interface C: A {
+    override val foo: String
+}
+interface B: A {
+    override var foo: String?
+}
+
+fun <T> test(a: T) where T : B, T : C {
+    a.<!AMBIGUITY!>foo<!> = ""
+    a.<!AMBIGUITY!>foo<!> = null
+
+    a.<!AMBIGUITY!>foo<!>.<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/simple.fir.kt b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/simple.fir.kt
new file mode 100644
index 00000000000..3eb3f039f43
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/simple.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+interface A {
+    fun foo()
+}
+
+interface C: A
+interface B: A
+
+fun <T> test(x: T) where T : C?, T : B? {
+    x?.foo()
+    if (x != null) {
+        x.foo()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/validTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/validTypeParameters.fir.kt
new file mode 100644
index 00000000000..dec6653fa20
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/multipleBoundsMemberScope/validTypeParameters.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+interface A {
+    fun <T, E> foo(): E
+}
+
+interface B {
+    fun <Q, W> foo(): W
+}
+
+fun <T> test(x: T) where T : B, T : A {
+    x.<!AMBIGUITY!>foo<!><String, Int>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/capturedTypeWithPlatformSupertype.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/capturedTypeWithPlatformSupertype.fir.kt
new file mode 100644
index 00000000000..fe61ad8e7a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/capturedTypeWithPlatformSupertype.fir.kt
@@ -0,0 +1,17 @@
+// FILE: First.java
+
+public class First<T extends Sample> {
+    public static <D extends Sample> void bind(First<D> first) {}
+}
+
+// FILE: SubFirst.java
+
+public class SubFirst<D extends Sample> extends First<D> {}
+
+// FILE: test.kt
+
+interface Sample
+
+fun test(s: SubFirst<*>) {
+    First.bind(s)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/considerTypeNotNullOnlyIfItHasNotNullBound.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/considerTypeNotNullOnlyIfItHasNotNullBound.fir.kt
new file mode 100644
index 00000000000..cd7358e05ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/considerTypeNotNullOnlyIfItHasNotNullBound.fir.kt
@@ -0,0 +1,6 @@
+// !LANGUAGE: +NewInference
+
+inline fun <T, reified S> foo(x: T?, y: T): T {
+    if (x is S) return x
+    return y
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/correctSubstitutionForIncorporationConstraint.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/correctSubstitutionForIncorporationConstraint.fir.kt
new file mode 100644
index 00000000000..c2f2f51f2ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/correctSubstitutionForIncorporationConstraint.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: JClass.java
+
+public class JClass {
+    public <K> void foo(Key<K> key, K value) {}
+}
+
+// FILE: test.kt
+
+class Key<T>
+
+fun <S> select(x: S, y: S): S = x
+
+fun <T> setValue(key: Key<T>, value: T, j: JClass) {
+    j.foo(key, select(value, null))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/declarationsBoundsViolation.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/declarationsBoundsViolation.fir.kt
new file mode 100644
index 00000000000..3e4dd070b0a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/declarationsBoundsViolation.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A<T : CharSequence>
+
+fun <S : CharSequence?> foo1(a: A<S>) {}
+
+class B1<E : String?> : A<E>
+class B2<E : CharSequence?> : A<E>
+class B3<E> : A<E>
+
+class B4<E : CharSequence> : A<E>
+
+fun <X : CharSequence, Y1 : X, Y2: Y1?> foo(a: A<X>, b: A<Y1>, c: A<Y2>) {}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/expressionsBoundsViolation.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/expressionsBoundsViolation.fir.kt
new file mode 100644
index 00000000000..03e3a5d44db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/expressionsBoundsViolation.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T : CharSequence>(x: T)
+
+fun <E : CharSequence> foo1(x: E) {}
+fun <E : CharSequence> E.foo2() {}
+
+fun <F : String?> bar(x: F) {
+    <!INAPPLICABLE_CANDIDATE!>A<!>(x)
+    <!INAPPLICABLE_CANDIDATE!>A<!><F>(x)
+
+    <!INAPPLICABLE_CANDIDATE!>foo1<!>(x)
+    <!INAPPLICABLE_CANDIDATE!>foo1<!><F>(x)
+
+    x.<!INAPPLICABLE_CANDIDATE!>foo2<!>()
+    x.<!INAPPLICABLE_CANDIDATE!>foo2<!><F>()
+}
+
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/functionalBound.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/functionalBound.fir.kt
new file mode 100644
index 00000000000..24faa0a169e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/functionalBound.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+fun <E : String?, T : ((CharSequence) -> Unit)?> foo(x: E, y: T) {
+    if (x != null) {
+        y(x)
+    }
+
+    if (y != null) {
+        y(x)
+    }
+
+    if (x != null && y != null) {
+        y(x)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/inferNotNullTypeFromIntersectionOfNullableTypes.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/inferNotNullTypeFromIntersectionOfNullableTypes.fir.kt
new file mode 100644
index 00000000000..0a8e1644657
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/inferNotNullTypeFromIntersectionOfNullableTypes.fir.kt
@@ -0,0 +1,38 @@
+// !LANGUAGE: +NewInference
+
+fun simpleTypeAndNumberType(b: Comparable<*>?) {
+    if (b is Byte?) {
+        b!!.dec()
+    }
+}
+
+fun <T> typeParmeterAndNumberType(b: T?) {
+    if (b is Byte?) {
+        b!!.dec()
+    }
+}
+
+fun anyAndNumberType(b: Any?) {
+    if (b is Byte?) {
+        b!!.dec()
+    }
+}
+
+fun comparableAndNumberType(b: Comparable<Byte>?) {
+    if (b is Byte?) {
+        b!!.dec()
+    }
+}
+
+object SeparateTypes {
+    interface A
+    interface B {
+        fun foo() {}
+    }
+
+    fun separate(a: A?) {
+        if (a is B?) {
+            a!!.foo()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/kt25182.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/kt25182.fir.kt
new file mode 100644
index 00000000000..3ed6a5ebf86
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/kt25182.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+abstract class Expr<T>
+
+class Sum<K>(val e: Expr<K>) : Expr<K?>()
+
+private fun <V> times(e: Expr<V>, element: V): Expr<V> = TODO()
+
+private fun <S> foo(e: Expr<S>) {}
+
+fun test(intExpression: Expr<Int>) {
+    foo(Sum(times(intExpression, 42)))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/notNullSmartcastOnIntersectionOfNullables.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/notNullSmartcastOnIntersectionOfNullables.fir.kt
new file mode 100644
index 00000000000..dd0d6de0461
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/notNullSmartcastOnIntersectionOfNullables.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A
+interface B {
+    fun test() {}
+}
+
+fun <K> select(a: K, b: K): K = a
+
+fun test(a: A?, b: B?) {
+    b as A?
+    a as B?
+    val c = select(a, b)
+    if (c != null) {
+        c.test()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/nullToGeneric.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/nullToGeneric.fir.kt
new file mode 100644
index 00000000000..09fe0b3722a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/nullToGeneric.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
+
+fun <E> bar(x: E) {}
+
+fun <T> foo(): T {
+    val x1: T = null
+    val x2: T? = null
+
+    bar<T>(null)
+    bar<T?>(null)
+
+    return null
+}
+
+fun <T> baz(): T? = null
+
+fun <T> foobar(): T = null
+
+class A<F> {
+    fun xyz(x: F) {}
+
+    fun foo(): F {
+        val x1: F = null
+        val x2: F? = null
+
+        xyz(null)
+        bar<F?>(null)
+
+        return null
+    }
+
+    fun baz(): F? = null
+
+    fun foobar(): F = null
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/smartCastRefinedClass.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/smartCastRefinedClass.fir.kt
new file mode 100644
index 00000000000..914151e3715
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/smartCastRefinedClass.fir.kt
@@ -0,0 +1,13 @@
+fun <T : Any?> foo(x: T) {
+    if (x is String?) {
+        x.length
+
+        if (x != null) {
+            x.length
+        }
+    }
+
+    if (x is String) {
+        x.length
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/smartCasts.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/smartCasts.fir.kt
new file mode 100644
index 00000000000..ba669aa51d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/smartCasts.fir.kt
@@ -0,0 +1,46 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION,-UNUSED_VARIABLE
+
+fun <T : CharSequence?> T.bar1() {}
+fun CharSequence?.bar2() {}
+
+fun <T : CharSequence> T.bar3() {}
+fun CharSequence.bar4() {}
+
+fun <T : CharSequence?> foo(x: T) {
+
+    if (x != null) {
+        if (x != null) {}
+
+        x.length
+        x?.length
+
+        x.bar1()
+        x.bar2()
+        x.bar3()
+        x.bar4()
+
+
+        x?.bar1()
+    }
+
+    x.length
+
+    if (x is String) {
+        x.<!AMBIGUITY!>length<!>
+        x?.<!AMBIGUITY!>length<!>
+
+        x.bar1()
+        x.bar2()
+        x.bar3()
+    }
+
+    if (x is CharSequence) {
+        x.length
+        x?.length
+
+        x.bar1()
+        x.bar2()
+        x.bar3()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/smartCastsOnThis.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/smartCastsOnThis.fir.kt
new file mode 100644
index 00000000000..afd4d5b9a6a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/smartCastsOnThis.fir.kt
@@ -0,0 +1,36 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION,-UNUSED_VARIABLE
+
+fun <T : CharSequence?> T.bar1() {}
+fun CharSequence?.bar2() {}
+
+fun <T : CharSequence> T.bar3() {}
+fun CharSequence.bar4() {}
+
+fun <T : String?> T.foo() {
+    if (this != null) {
+        if (this != null) {}
+
+        length
+        this?.length
+
+        bar1()
+        bar2()
+        bar3()
+        bar4()
+
+
+        this?.bar1()
+    }
+
+    length
+
+    if (this is String) {
+        length
+        this?.length
+
+        bar1()
+        bar2()
+        bar3()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/smartCastsValueArgument.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/smartCastsValueArgument.fir.kt
new file mode 100644
index 00000000000..7a9fb30501c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/smartCastsValueArgument.fir.kt
@@ -0,0 +1,52 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION,-UNUSED_VARIABLE,-UNUSED_PARAMETER,-ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE,-UNUSED_VALUE
+
+fun <T : CharSequence> bar1(x: T) {}
+fun bar2(x: CharSequence) {}
+fun bar3(x: String) {}
+
+fun <T : CharSequence?> foo(x: T) {
+    var y1: CharSequence = ""
+    var y2: String = ""
+    if (x != null) {
+        if (x != null) {}
+
+        y1 = x
+        y2 = x
+
+        bar1(x)
+        bar1<CharSequence>(x)
+        bar2(x)
+        <!INAPPLICABLE_CANDIDATE!>bar3<!>(x)
+    }
+
+    if (x is String) {
+        y1 = x
+        y2 = x
+
+        bar1(x)
+        bar2(x)
+        bar3(x)
+    }
+
+    if (x is CharSequence) {
+        y1 = x
+        y2 = x
+
+        bar1(x)
+        bar2(x)
+        <!INAPPLICABLE_CANDIDATE!>bar3<!>(x)
+    }
+
+    if (1 == 1) {
+        val y = x!!
+        bar1(x)
+        bar1<CharSequence>(x)
+        bar2(x)
+        <!INAPPLICABLE_CANDIDATE!>bar3<!>(x)
+
+        <!INAPPLICABLE_CANDIDATE!>bar1<!>(y)
+        bar2(y)
+        <!INAPPLICABLE_CANDIDATE!>bar3<!>(y)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolation.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolation.fir.kt
new file mode 100644
index 00000000000..5bfe4abd488
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolation.fir.kt
@@ -0,0 +1,49 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
+
+class A<F> {
+    fun <E : F> foo1(x: E) = x
+    fun <E : F?> foo2(x: E) = x
+
+    fun <Z : F, W : Z?> bar(x: F, y: F?, z: Z, w: W) {
+        foo1<F>(x)
+
+        val x1 = foo1(x)
+        x1.checkType { _<F>() }
+
+        foo2<F>(x)
+
+        val x2 = foo2(x)
+        x2.checkType { _<F>() }
+
+        <!INAPPLICABLE_CANDIDATE!>foo1<!><F?>(y)
+        foo1(y)
+        foo2<F?>(y)
+
+        val x3 = foo2(y)
+        x3.checkType { _<F?>() }
+
+        foo1<F>(y)
+        foo2<F>(y)
+
+        foo1<Z>(z)
+
+        val x4 = foo1(z)
+        x4.checkType { _<Z>() }
+
+        foo2<Z>(z)
+
+        val x5 = foo2(z)
+        x4.checkType { _<Z>() }
+
+        <!INAPPLICABLE_CANDIDATE!>foo1<!><W>(w)
+        <!INAPPLICABLE_CANDIDATE!>foo1<!>(w)
+        foo2<W>(w)
+
+        val x6 = foo2(w)
+        x6.checkType { _<W>() }
+
+        <!INAPPLICABLE_CANDIDATE!>foo1<!><W>(w)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolationVariance.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolationVariance.fir.kt
new file mode 100644
index 00000000000..24fb210b617
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolationVariance.fir.kt
@@ -0,0 +1,67 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
+
+class A<F> {
+    class Inv<Q>
+    fun <E : Inv<F>> fooInv1(x: E) = x
+    fun <E : Inv<F?>> fooInv2(x: E) = x
+
+    class In<in Q>
+    fun <E : In<F>> fooIn1(x: E) = x
+    fun <E : In<F?>> fooIn2(x: E) = x
+
+    class Out<out Q>
+    fun <E : Out<F>> fooOut1(x: E) = x
+    fun <E : Out<F?>> fooOut2(x: E) = x
+
+    fun <Z : F, W : Z?> bar() {
+        // F
+        fooInv1<Inv<F>>(Inv<F>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv2<!><Inv<F>>(Inv<F>())
+        fooInv1(Inv<F>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv2<!>(Inv<F>())
+
+        fooIn1<In<F?>>(In<F?>())
+        fooIn2<In<F?>>(In<F?>())
+        fooIn1(In<F?>())
+        fooIn2(In<F?>())
+
+        fooOut1<Out<F>>(Out<F>())
+        fooOut2<Out<F>>(Out<F>())
+        fooOut1(Out<F>())
+        fooOut2(Out<F>())
+
+        // Z
+        <!INAPPLICABLE_CANDIDATE!>fooInv1<!><Inv<Z>>(Inv<Z>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv2<!><Inv<Z>>(Inv<Z>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv1<!>(Inv<Z>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv2<!>(Inv<Z>())
+
+        <!INAPPLICABLE_CANDIDATE!>fooIn1<!><In<Z?>>(In<Z?>())
+        <!INAPPLICABLE_CANDIDATE!>fooIn2<!><In<Z?>>(In<Z?>())
+        <!INAPPLICABLE_CANDIDATE!>fooIn1<!>(In<Z?>())
+        <!INAPPLICABLE_CANDIDATE!>fooIn2<!>(In<Z?>())
+
+        fooOut1<Out<Z>>(Out<Z>())
+        fooOut2<Out<Z>>(Out<Z>())
+        fooOut1(Out<Z>())
+        fooOut2(Out<Z>())
+
+        // W
+        <!INAPPLICABLE_CANDIDATE!>fooInv1<!><Inv<W>>(Inv<W>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv2<!><Inv<W>>(Inv<W>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv1<!>(Inv<W>())
+        <!INAPPLICABLE_CANDIDATE!>fooInv2<!>(Inv<W>())
+
+        <!INAPPLICABLE_CANDIDATE!>fooIn1<!><In<W?>>(In<W?>())
+        <!INAPPLICABLE_CANDIDATE!>fooIn2<!><In<W?>>(In<W?>())
+        <!INAPPLICABLE_CANDIDATE!>fooIn1<!>(In<W?>())
+        <!INAPPLICABLE_CANDIDATE!>fooIn2<!>(In<W?>())
+
+        <!INAPPLICABLE_CANDIDATE!>fooOut1<!><Out<W>>(Out<W>())
+        fooOut2<Out<W>>(Out<W>())
+        <!INAPPLICABLE_CANDIDATE!>fooOut1<!>(Out<W>())
+        fooOut2(Out<W>())
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/tpInBounds.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/tpInBounds.fir.kt
new file mode 100644
index 00000000000..3e24720fdd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/tpInBounds.fir.kt
@@ -0,0 +1,40 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VALUE,-UNUSED_VARIABLE,-ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE,-VARIABLE_WITH_REDUNDANT_INITIALIZER
+
+class A<T : CharSequence?, E1 : T, E2: T?> {
+    fun T.bar() {}
+
+    fun foo(x: E1, y: E2) {
+        x.bar()
+
+        if (1 == 1) {
+            y.<!INAPPLICABLE_CANDIDATE!>bar<!>()
+        }
+
+        x?.bar()
+        y?.bar()
+
+
+        var t: T = x
+        var tN: T? = y
+
+        // condition needed to make smart cast on tN impossible
+        if (1 == 1) {
+            tN = x
+        }
+
+        if (1 == 1) {
+            t = tN
+        }
+
+        t = y
+
+        if (y != null) {
+            t = y
+        }
+
+        if (tN != null) {
+            t = tN
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/useAsReceiver.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/useAsReceiver.fir.kt
new file mode 100644
index 00000000000..c8f52d3f8cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/useAsReceiver.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION,-UNUSED_VARIABLE
+
+fun <T : CharSequence?> T.bar1() {}
+fun CharSequence?.bar2() {}
+
+fun <T : CharSequence> T.bar3() {}
+
+fun <T : String?> foo(x: T) {
+    x.length
+    x?.length
+
+    if (1 == 1) {
+        x!!.length
+    }
+
+
+    x.bar1()
+    x.bar2()
+
+    x?.bar1()
+    x?.bar2()
+
+    x.<!INAPPLICABLE_CANDIDATE!>bar3<!>()
+
+    x?.let { it.length }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/useAsValueArgument.fir.kt b/compiler/testData/diagnostics/tests/generics/nullability/useAsValueArgument.fir.kt
new file mode 100644
index 00000000000..7892ecac4e7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/nullability/useAsValueArgument.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
+
+fun <T : CharSequence?> bar1(x: T) {}
+
+fun bar2(x: CharSequence?) {}
+
+fun <T : CharSequence> bar3(x: T) {}
+
+fun bar4(x: String) {}
+
+fun <T : String?> foo(x: T) {
+    bar1(x)
+    bar2(x)
+
+    <!INAPPLICABLE_CANDIDATE!>bar3<!>(x)
+    bar4(x)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/MLOut.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/MLOut.fir.kt
new file mode 100644
index 00000000000..082106edebe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/MLOut.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+// FILE: A.java
+public class A {
+    public java.util.List<? extends CharSequence> foo() {}
+}
+
+// FILE: main.kt
+
+fun foo2(x: A, y: MutableList<out CharSequence>) {
+    x.foo().isEmpty()
+    x.foo().get(0) checkType { <!UNRESOLVED_REFERENCE!>_<!><CharSequence>() }
+    x.foo().iterator() checkType { <!UNRESOLVED_REFERENCE!>_<!><MutableIterator<CharSequence>>() }
+
+    y.isEmpty()
+    y.get(0) checkType { <!UNRESOLVED_REFERENCE!>_<!><CharSequence>() }
+    y.iterator() checkType { <!UNRESOLVED_REFERENCE!>_<!><MutableIterator<CharSequence>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/addAll.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/addAll.fir.kt
new file mode 100644
index 00000000000..f5fc027d2df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/addAll.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface C<out T>
+interface MC<T> : C<T> {
+    fun addAll(x: C<T>): Boolean
+    fun addAllMC(x: MC<out T>): Boolean
+    fun addAllInv(x: MC<T>): Boolean
+}
+
+interface Open
+class Derived : Open
+
+fun <T> mc(): MC<T> = null!!
+fun <T> c(): C<T> = null!!
+
+fun foo(x: MC<out Open>) {
+    x.addAll(x)
+    x.addAllMC(x)
+
+    x.addAll(mc<Open>())
+    x.addAllMC(mc<Open>())
+
+    x.addAll(mc<Derived>())
+    x.addAllMC(mc<Derived>())
+
+    x.addAll(c())
+    x.addAll(c<Nothing>())
+
+    x.addAllInv(mc<Open>())
+    x.<!INAPPLICABLE_CANDIDATE!>addAll<!>(1)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/approximateDispatchReceiver.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/approximateDispatchReceiver.fir.kt
new file mode 100644
index 00000000000..7c3a4681b6b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/approximateDispatchReceiver.fir.kt
@@ -0,0 +1,14 @@
+// !CHECK_TYPE
+
+public abstract class A<E> {
+    fun bar(): String = ""
+}
+
+public class B<F> : A<B<F>>()
+
+fun test(b: B<*>) {
+    // Here `bar` could have dispatch receiver parameter type 'A<B<Captured(*)>>', but it wouldn't work as
+    // since 'b' has type 'A<out B<*>>', so we should approximate dispatch receiver PARAMETER type to make it accept original receiver
+    b.bar()
+    b.bar() checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/extensionReceiverTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/extensionReceiverTypeMismatch.fir.kt
new file mode 100644
index 00000000000..69cd0e36317
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/extensionReceiverTypeMismatch.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+class A<T> {
+    fun T.foo() {}
+    fun Out<T>.bar() {}
+}
+class Out<out E>
+
+fun test(x: A<out CharSequence>, y: Out<CharSequence>) {
+    with(x) {
+        // TODO: this diagnostic could be replaced with TYPE_MISMATCH_DUE_TO_TYPE_PROJECTION
+        "".foo()
+        y.bar()
+
+        with(y) {
+            bar()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/extensionResultSubstitution.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/extensionResultSubstitution.fir.kt
new file mode 100644
index 00000000000..a200e8f6eee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/extensionResultSubstitution.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T> {
+    fun foo() = 1
+}
+
+interface B
+
+public fun <E : B> E.bar() : A<out E> = null!!
+
+fun baz(x: B) {
+    x.bar().foo()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/flexibleProjectedScope.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/flexibleProjectedScope.fir.kt
new file mode 100644
index 00000000000..1556a5dd960
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/flexibleProjectedScope.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+// !CHECK_TYPE
+
+// FILE: Clazz.java
+public class Clazz<Psi> {
+    public java.util.Collection<Psi> foo() { return null; }
+}
+
+// FILE: main.kt
+
+public fun <T, C : MutableCollection<in T>> Iterable<T>.filterTo(destination: C, predicate: (T) -> Boolean) {}
+
+fun test(clazz: Clazz<out Any>) {
+    val result = java.util.<!UNRESOLVED_REFERENCE!>ArrayList<!><Any>()
+    clazz.foo().<!INAPPLICABLE_CANDIDATE!>filterTo<!>(result) { x -> true }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/inValueParameter.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/inValueParameter.fir.kt
new file mode 100644
index 00000000000..860f65e3b75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/inValueParameter.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+interface A<T>
+interface B<E> {
+    fun foo(x: A<in E>)
+}
+
+fun foo(x: B<in CharSequence>, y: A<CharSequence>) {
+    x.foo(y)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/iterateOnExtension.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/iterateOnExtension.fir.kt
new file mode 100644
index 00000000000..28aa35be026
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/iterateOnExtension.fir.kt
@@ -0,0 +1,11 @@
+class A<T>
+fun <T> A<T>.foo(): Collection<T> = null!!
+
+fun main(a: A<*>, a1: A<out CharSequence>) {
+    // see KT-9571
+    for (i in a.foo()) { }
+    for (i: Any? in a.foo()) { }
+
+    for (i in a1.foo()) { }
+    for (i: CharSequence in a1.foo()) { }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/kt7296.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/kt7296.fir.kt
new file mode 100644
index 00000000000..c609458644b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/kt7296.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !CHECK_TYPE
+import java.util.ArrayList
+
+class ListOfLists<T>(public val x : ArrayList<ArrayList<T>>)
+
+fun main() {
+    val a : ArrayList<ArrayList<String>> = ArrayList()
+    val b : ListOfLists<String> = ListOfLists(a)
+    val c : ListOfLists<*> = b
+    val d : ArrayList<ArrayList<*>> = c.x
+
+    c.x checkType { <!UNRESOLVED_REFERENCE!>_<!><ArrayList<out ArrayList<*>>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/kt8647.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/kt8647.fir.kt
new file mode 100644
index 00000000000..0873de21fd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/kt8647.fir.kt
@@ -0,0 +1,8 @@
+interface Subscriber<T>
+
+interface Observable<T> {
+    fun subscribe(s: Subscriber<in T>)
+}
+
+fun foo(o: Observable<out CharSequence>, y: Subscriber<in CharSequence>) = o.subscribe(y) // type safe
+
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/lambdaArgument.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/lambdaArgument.fir.kt
new file mode 100644
index 00000000000..35247f1b5d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/lambdaArgument.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+class A<T> {
+    fun foo(f: (T) -> Unit) {}
+}
+
+fun test(a: A<out Number>, b: A<in Number>) {
+    a.foo {
+        it checkType { _<Number>() }
+    }
+
+    b.foo {
+        it checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Any?>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/leakedApproximatedType.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/leakedApproximatedType.fir.kt
new file mode 100644
index 00000000000..a5262457bdd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/leakedApproximatedType.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Out<out T>
+class In<in T> {
+    fun invoke1(x: T) {}
+    fun invoke2(x: Out<T>) {}
+}
+
+interface A<E> {
+    fun foo(): In<E>
+}
+
+fun test(a: A<out CharSequence>, y: Out<CharSequence>) {
+    val i = a.foo()
+    // TODO: These diagnostic are wrong, type of 'i' --- 'In<Nothing>' is not projected itself,
+    // but it's approximation result caused by 'a' projection
+    i.invoke1("")
+    i.invoke2(y)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/multipleArgumentProjectedOut.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/multipleArgumentProjectedOut.fir.kt
new file mode 100644
index 00000000000..e7dd1a5f2e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/multipleArgumentProjectedOut.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T> {
+    fun foo(x: T, y: T) {}
+}
+
+fun test(a: A<out CharSequence>) {
+    a.foo("", "")
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/platformSuperClass.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/platformSuperClass.fir.kt
new file mode 100644
index 00000000000..f44f0a6ed53
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/platformSuperClass.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+// FILE: Clazz.java
+public class Clazz<T> {
+    public T getT() { return null; }
+    public Clazz<? super T> getSuperClass() { return null; }
+}
+
+// FILE: main.kt
+fun test(clazz: Clazz<*>) {
+    clazz.t checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    clazz.getSuperClass() checkType { <!UNRESOLVED_REFERENCE!>_<!><Clazz<*>?>() }
+    clazz.getSuperClass().t checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+
+    clazz.superClass checkType { <!UNRESOLVED_REFERENCE!>_<!><Clazz<*>?>() }
+    clazz.superClass.t checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+
+    // See KT-9294
+    if (clazz.superClass == null) {
+        throw NullPointerException()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/projectedOutConventions.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/projectedOutConventions.fir.kt
new file mode 100644
index 00000000000..aeeb144c0bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/projectedOutConventions.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T> {
+    operator fun plus(x: T): A<T> = this
+    operator fun set(x: Int, y: T) {}
+    operator fun get(x: T) = 1
+}
+
+fun test(a: A<out CharSequence>) {
+    a + ""
+    a[1] = ""
+    a[""]
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/projectedOutSmartCast.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/projectedOutSmartCast.fir.kt
new file mode 100644
index 00000000000..7b905950ad9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/projectedOutSmartCast.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class Inv<E>
+class C<R> {
+    fun bindTo(property: Inv<R>) {}
+}
+
+fun foo(x: Any?, y: C<*>) {
+    y.<!INAPPLICABLE_CANDIDATE!>bindTo<!>("")
+
+    if (x is C<*>) {
+        x.<!INAPPLICABLE_CANDIDATE!>bindTo<!>("")
+        with(x) {
+            <!INAPPLICABLE_CANDIDATE!>bindTo<!>("")
+        }
+    }
+
+    with(x) {
+        if (this is C<*>) {
+            <!INAPPLICABLE_CANDIDATE!>bindTo<!>("")
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/recursiveUpperBoundStar.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/recursiveUpperBoundStar.fir.kt
new file mode 100644
index 00000000000..c2abfc7d52e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/recursiveUpperBoundStar.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// See KT-7296
+interface A<T>
+interface B<T> : A<A<T>>
+
+fun foo(x : B<*>) {
+    <!INAPPLICABLE_CANDIDATE!>bar1<!>(x) // this should not be valid
+    bar2(x)
+    bar3(x)
+}
+
+fun bar1(x : A<A<*>>) { }
+fun bar2(x : A<out A<*>>) { }
+fun bar3(x : A<*>) { }
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/recursiveUpperBoundStarOut.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/recursiveUpperBoundStarOut.fir.kt
new file mode 100644
index 00000000000..80c221107c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/recursiveUpperBoundStarOut.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// See KT-7296
+interface Out<out F>
+interface B<T> : Out<Out<T>>
+
+fun foo(x : B<*>) {
+    bar1(x)
+    bar2(x)
+}
+
+fun bar1(x : Out<Out<*>>) { }
+fun bar2(x : Out<*>) { }
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/starNullability.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/starNullability.fir.kt
new file mode 100644
index 00000000000..26ff7f50583
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/starNullability.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// See KT-9893
+open class A
+
+public interface I<T : A> {
+    public fun foo(): T?
+}
+
+fun acceptA(a: A) {
+}
+
+fun main(i: I<*>) {
+    i.foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><A?>() }
+    acceptA(i.foo()) // i.foo() should be nullable but isn't
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/starNullabilityRecursive.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/starNullabilityRecursive.fir.kt
new file mode 100644
index 00000000000..ed7aedae6a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/starNullabilityRecursive.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+interface A<T : A<T?>?> {
+    fun foo(): T?
+}
+fun testA(a: A<*>) {
+    a.foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><A<*>?>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/superClass.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/superClass.fir.kt
new file mode 100644
index 00000000000..e0963df5033
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/superClass.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+interface Clazz<T> {
+    val t: T
+    fun getSuperClass(): Clazz<in T>
+}
+
+fun test(clazz: Clazz<*>) {
+    clazz.t checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    clazz.getSuperClass() checkType { <!UNRESOLVED_REFERENCE!>_<!><Clazz<*>>() }
+    clazz.getSuperClass().t checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/typeMismatchConventions.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/typeMismatchConventions.fir.kt
new file mode 100644
index 00000000000..f976f1248d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/typeMismatchConventions.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T> {
+    operator fun plus(x: Out<T>): A<T> = this
+    operator fun set(x: Int, y: Out<T>) {}
+    operator fun get(x: Out<T>) = 1
+}
+
+class Out<out F>
+
+fun test(a: A<out CharSequence>, y: Out<CharSequence>) {
+    a + y
+    a[1] = y
+    a[y]
+
+    a + Out<Nothing>()
+    a[1] = Out<Nothing>()
+    a[Out<Nothing>()]
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/typeMismatchInLambda.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/typeMismatchInLambda.fir.kt
new file mode 100644
index 00000000000..a16b1db7271
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/typeMismatchInLambda.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class Out<out T> {
+    fun id() = this
+    fun foobar(x: Any) {}
+}
+
+class A<E> {
+    inline fun foo(block: () -> E) {}
+    inline fun bar(block: () -> Out<E>) {}
+}
+
+fun test(a: A<out CharSequence>, z: Out<CharSequence>) {
+    a.foo {
+        val x: String = 1 // Should be no TYPE_MISMATCH_DUE_TO_TYPE_PROJECTIONS
+        ""
+    }
+    a.bar { Out<CharSequence>() }
+    a.bar { Out() }
+    a.bar { z.id() }
+
+    a.foo {
+        z.foobar(if (1 > 2) return@foo "" else "")
+        ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/typeParameterBounds.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/typeParameterBounds.fir.kt
new file mode 100644
index 00000000000..de0ef7c1b87
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/typeParameterBounds.fir.kt
@@ -0,0 +1,44 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Out<out X>
+class In<in Y>
+class Inv<Z>
+
+class A<T> {
+    fun <E : Out<T>> foo1(x: E) = 1
+    fun <F : Inv<T>> foo2(x: F) = 1
+    fun <G : In<T>>  foo3(x: G) = 1
+}
+
+fun foo2(a: A<out CharSequence>, b: A<in CharSequence>) {
+    a.foo1(Out<CharSequence>())
+    a.foo1<Out<CharSequence>>(Out())
+
+    a.foo1(Out())
+    a.foo1(Out<Nothing>())
+
+    a.foo2(Inv())
+    a.foo2(Inv<CharSequence>())
+    a.foo2<Inv<CharSequence>>(Inv())
+
+    a.foo3(In())
+    a.foo3(In<CharSequence>())
+    a.foo3<In<CharSequence>>(In())
+
+    b.foo1(Out())
+    b.foo1(Out<CharSequence>())
+    b.foo1<Out<CharSequence>>(Out())
+
+    b.foo2(Inv())
+    b.foo2(Inv<CharSequence>())
+    b.foo2<Inv<CharSequence>>(Inv())
+
+
+    b.foo3(In<CharSequence>())
+    b.foo3<In<CharSequence>>(In())
+
+    b.foo3(In<Any?>())
+    b.foo3(In())
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/unsafeVarianceStar.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/unsafeVarianceStar.fir.kt
new file mode 100644
index 00000000000..10f4635a1d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/unsafeVarianceStar.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+
+interface A<out K> {
+    fun foo(x: @UnsafeVariance K): Unit
+}
+
+fun test(a: A<*>) {
+    a.foo(null)
+    a.foo(Any())
+}
diff --git a/compiler/testData/diagnostics/tests/generics/projectionsScope/varargs.fir.kt b/compiler/testData/diagnostics/tests/generics/projectionsScope/varargs.fir.kt
new file mode 100644
index 00000000000..bb2deafe59f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/projectionsScope/varargs.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T> {
+    fun foo(vararg x: T) {}
+}
+
+fun test(a: A<out CharSequence>, y: Array<out CharSequence>) {
+    a.foo("", "", "")
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>(*y)
+    // TODO: TYPE_MISMATCH_DUE_TO_TYPE_PROJECTIONS probably redundant
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>(*y, "")
+}
diff --git a/compiler/testData/diagnostics/tests/generics/protectedSuperCall.fir.kt b/compiler/testData/diagnostics/tests/generics/protectedSuperCall.fir.kt
new file mode 100644
index 00000000000..7b2439480e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/protectedSuperCall.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// FILE: GA.kt
+
+package test.x
+
+open class GA<T> protected constructor()
+
+// FILE: Main.kt
+package test
+
+import test.x.GA
+
+class C : GA<Any>() {
+    companion object {
+        fun bar() = GA<Any>() // Should be error
+    }
+}
+
+fun main(args: Array<String>) {
+    C.bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/recursive.fir.kt b/compiler/testData/diagnostics/tests/generics/recursive.fir.kt
new file mode 100644
index 00000000000..690c18b7f65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/recursive.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE
+
+interface Rec<T>
+class A : Rec<A>
+class B : Rec<B>
+
+fun test(a: A, b: B, c: Boolean) {
+    var ab = if (c) a else b
+    ab = a
+    ab = b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/resolveGenericBoundsBeforeSupertypes.fir.kt b/compiler/testData/diagnostics/tests/generics/resolveGenericBoundsBeforeSupertypes.fir.kt
new file mode 100644
index 00000000000..543e3f9646b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/resolveGenericBoundsBeforeSupertypes.fir.kt
@@ -0,0 +1,7 @@
+// Tests that generic bounds in the object supertype are resolved prior to the supertype itself
+
+object O : Tr<V<*>>
+
+interface Tr<T>
+
+class V<out S>
diff --git a/compiler/testData/diagnostics/tests/generics/sameTypeParameterUse.fir.kt b/compiler/testData/diagnostics/tests/generics/sameTypeParameterUse.fir.kt
new file mode 100644
index 00000000000..319b5bc8737
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/sameTypeParameterUse.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun <R> foo(x: R, y: String) {}
+fun <R> foo(x: R, y: R) {
+    foo<R>(x, "") // ok, resolved foo(x: R, y: String)
+    foo(x, "") // ok, foo(x: R, y: String)
+    foo<R>(x, x) // ok, resolved foo(x: R, y: R)
+    foo(x, x) // ok, resolved foo(x: R, y: R)
+}
+
+class Q<R>(x: R) {
+    fun foo() {
+        Q<R>("")
+    }
+}
+fun <R> Q(x: String) {}
diff --git a/compiler/testData/diagnostics/tests/generics/starProjections/checkBounds.fir.kt b/compiler/testData/diagnostics/tests/generics/starProjections/checkBounds.fir.kt
new file mode 100644
index 00000000000..17f1e033cf6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/starProjections/checkBounds.fir.kt
@@ -0,0 +1,3 @@
+class A<T : A<T>>
+fun <T : A<*>> foo() {}
+class B<T : A<*>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/starProjections/collectionInheritedFromJava.fir.kt b/compiler/testData/diagnostics/tests/generics/starProjections/collectionInheritedFromJava.fir.kt
new file mode 100644
index 00000000000..5e09012121d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/starProjections/collectionInheritedFromJava.fir.kt
@@ -0,0 +1,14 @@
+// FILE: p/Base.java
+
+package p;
+
+import java.util.*;
+
+public class Base<T> {
+    void coll(Collection<?> r) {}
+}
+
+// FILE: k.kt
+package p
+
+class Derived: p.Base<String>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/starProjections/inheritedFromJava.fir.kt b/compiler/testData/diagnostics/tests/generics/starProjections/inheritedFromJava.fir.kt
new file mode 100644
index 00000000000..caf29f2990a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/starProjections/inheritedFromJava.fir.kt
@@ -0,0 +1,14 @@
+// FILE: p/Base.java
+
+package p;
+
+public class Base<T> {
+    void foo(R<?> r) {}
+}
+
+// FILE: k.kt
+package p
+
+class R<T: R<T>>
+
+class Derived: p.Base<String>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/starProjections/inheritedFromKotlin.fir.kt b/compiler/testData/diagnostics/tests/generics/starProjections/inheritedFromKotlin.fir.kt
new file mode 100644
index 00000000000..bcf02a0e721
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/starProjections/inheritedFromKotlin.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class R<T: R<T>>
+
+open class Base<T> {
+    fun foo(r: R<*>) {}
+}
+
+class Derived: Base<String>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/starProjections/invalid.fir.kt b/compiler/testData/diagnostics/tests/generics/starProjections/invalid.fir.kt
new file mode 100644
index 00000000000..068e1c105b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/starProjections/invalid.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: main.kt
+class Inv<T>(val x: T)
+
+class A<T : Inv<in T>> {
+    fun foo(): T = null!!
+}
+
+class Inv2<T : Inv2<in T>>(val x: T)
+
+fun main(a: A<*>, j: JavaClass<*>, i2: Inv2<*>) {
+    // Probably it's too restrictive to suppose star projection type here as Any?,
+    // but looks like we can refine it later
+    a.foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    j.foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    i2.x checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+
+    j.<!INAPPLICABLE_CANDIDATE!>bar<!>(1, 2, Any())
+    j.bar(null)
+}
+
+// FILE: JavaClass.java
+public class JavaClass<T extends JavaClass<? super T>> {
+    public void bar(T... x) {}
+    public T foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/generics/suppressVarianceConflict.fir.kt b/compiler/testData/diagnostics/tests/generics/suppressVarianceConflict.fir.kt
new file mode 100644
index 00000000000..553af5275bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/suppressVarianceConflict.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class A<out T, in E> {
+    fun foo(x: @UnsafeVariance T) {}
+    fun foo(x: @UnsafeVariance T, y: List<@UnsafeVariance T>): @UnsafeVariance E = null!!
+
+    fun bar(): List<@UnsafeVariance E> = null!!
+}
+
+fun foo(x: A<String, Any?>, cs: CharSequence, ls: List<CharSequence>) {
+    val y: A<CharSequence, String> = x
+
+    y.foo(cs)
+    val s: String = y.foo(cs, ls)
+
+    val ls2: List<String> = y.bar()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/CapturedAsReified.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/CapturedAsReified.fir.kt
new file mode 100644
index 00000000000..8402c98cef4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/CapturedAsReified.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A<F>
+
+inline fun <reified T> foo(x: A<T>) {}
+
+fun test(x: A<out CharSequence>) {
+    foo(x)
+}
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/ClassDereference.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/ClassDereference.fir.kt
new file mode 100644
index 00000000000..758753b3116
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/ClassDereference.fir.kt
@@ -0,0 +1,3 @@
+
+fun <T: Any> dereferenceClass(): Any =
+        <!OTHER_ERROR!>T<!>::class
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/Conventions.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/Conventions.fir.kt
new file mode 100644
index 00000000000..377d73d3998
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/Conventions.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline operator fun <reified T> T.plus(p: T): T = this
+
+inline operator fun <reified T> T.invoke(): T  = this
+
+fun <A> main(tp: A, any: Any) {
+    tp + tp
+    any + any
+
+    tp()
+    any()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgument.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgument.fir.kt
new file mode 100644
index 00000000000..cff415b6311
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgument.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +ProhibitNonReifiedArraysAsReifiedTypeArguments
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun <reified T> foo() {}
+
+fun <T> bar() {
+    foo<T>()
+    foo<Array<T>>()
+    foo<Array<Array<T>>>()
+    foo<Array<Int>>()
+    foo<Array<Array<Int>>>()
+    foo<IntArray>()
+    foo<List<T>>()
+    foo<List<Array<T>>>()
+}
+
+fun test(x: Array<String>, y: Array<*>) {
+    bar<Int>()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgumentWarning.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgumentWarning.fir.kt
new file mode 100644
index 00000000000..ae665ca8b29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericArrayAsReifiedArgumentWarning.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: -ProhibitNonReifiedArraysAsReifiedTypeArguments
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun <reified T> foo() {}
+
+fun <T> bar() {
+    foo<T>()
+    foo<Array<T>>()
+    foo<Array<Array<T>>>()
+    foo<Array<Int>>()
+    foo<Array<Array<Int>>>()
+    foo<IntArray>()
+    foo<List<T>>()
+    foo<List<Array<T>>>()
+}
+
+fun test(x: Array<String>, y: Array<*>) {
+    bar<Int>()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericAsReifiedArgument.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericAsReifiedArgument.fir.kt
new file mode 100644
index 00000000000..b201042e828
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/GenericAsReifiedArgument.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun <reified T> foo() {}
+
+inline fun <reified F> bar() {
+    foo<Array<F>>()
+    foo<List<F>>()
+}
+
+inline fun <reified E> baz(x: E) {}
+
+fun test(x: Array<String>, y: Array<*>) {
+    foo<List<String>>()
+    foo<List<*>>()
+    foo<Map<*, String>>()
+    foo<Map<*, *>>()
+
+    foo<Array<String>>()
+    foo<Array<*>>()
+
+    baz(x)
+    baz(y)
+}
+
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/InConstructor.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/InConstructor.fir.kt
new file mode 100644
index 00000000000..241f164149f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/InConstructor.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+class C<reified T>
+
+fun <T> id(p: T): T = p
+
+fun <A> main() {
+    C()
+
+    val a: C<A> = C()
+    C<A>()
+
+    val b: C<Int> = C()
+    C<Int>()
+
+    // TODO svtk, uncomment when extensions are called for nested calls!
+    //val < !UNUSED_VARIABLE!>с< !>: C<A> = id(< !TYPE_PARAMETER_AS_REIFIED!>C< !>())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/InFunction.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/InFunction.fir.kt
new file mode 100644
index 00000000000..bdac536027a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/InFunction.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun <reified T> f(): T = throw UnsupportedOperationException()
+
+fun <T> id(p: T): T = p
+
+fun <A> main() {
+    f()
+
+    val a: A = f()
+    f<A>()
+
+    val b: Int = f()
+    f<Int>()
+
+    val с: A = id(f())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/InProperty.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/InProperty.fir.kt
new file mode 100644
index 00000000000..b1f7e802c2b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/InProperty.fir.kt
@@ -0,0 +1,2 @@
+val <reified T> T.v: T
+    get() = throw UnsupportedOperationException()
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/InType.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/InType.fir.kt
new file mode 100644
index 00000000000..6f5cac1d5c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/InType.fir.kt
@@ -0,0 +1,4 @@
+class C<reified T>
+
+fun <A> main(p1: C<A>, p2: C<Int>) {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/InlineableReified.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/InlineableReified.fir.kt
new file mode 100644
index 00000000000..d8c35c93cd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/InlineableReified.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun<T1, reified T2> bar(x: T1, y: T2): T2 = y
+inline fun<reified R> foo(z: R): R = bar(1, z)
+
+fun box() {
+    foo("abc")
+}
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/LocalFun.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/LocalFun.fir.kt
new file mode 100644
index 00000000000..e984a060a04
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/LocalFun.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -NOT_YET_SUPPORTED_IN_INLINE
+
+inline fun<reified T> foo(x: T) {
+    fun<reified R> bar() {
+
+    }
+
+    bar<T>()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/NotInlineableReified.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/NotInlineableReified.fir.kt
new file mode 100644
index 00000000000..c9a6bc6c2ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/NotInlineableReified.fir.kt
@@ -0,0 +1,4 @@
+
+fun<T1, reified T2, T3, reified T4> foo() {
+
+}
diff --git a/compiler/testData/diagnostics/tests/generics/tpAsReified/ReifiedClass.fir.kt b/compiler/testData/diagnostics/tests/generics/tpAsReified/ReifiedClass.fir.kt
new file mode 100644
index 00000000000..d12c8d6b0a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/tpAsReified/ReifiedClass.fir.kt
@@ -0,0 +1,3 @@
+class A<T1, reified T2, T3, reified T4> {
+    fun<reified R> foo(): T2 = throw UnsupportedOperationException()
+}
diff --git a/compiler/testData/diagnostics/tests/generics/unresolvedClassifierInWhere.fir.kt b/compiler/testData/diagnostics/tests/generics/unresolvedClassifierInWhere.fir.kt
new file mode 100644
index 00000000000..1b8f7fe01eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/unresolvedClassifierInWhere.fir.kt
@@ -0,0 +1,14 @@
+interface I0<T : Unresolved0<String>>
+interface I1<T> where T : Unresolved1<String>
+interface I2<T : Unresolved2<String>> where T : Unresolved3<String>
+
+fun <E : Unresolved4<String>> foo0() {}
+fun <E> foo1() where E : Unresolved5<String> {}
+fun <E : Unresolved6<String>> foo2() where E : Unresolved7<String> {}
+
+val <E : Unresolved7> E.p1: Int
+        get() = 1
+val <E> E.p2: Int where E : Unresolved8
+        get() = 1
+val <E : Unresolved9> E.p3: Int where E : Unresolved10
+        get() = 1
diff --git a/compiler/testData/diagnostics/tests/generics/varProjection/setterNotProjectedOutAssign.fir.kt b/compiler/testData/diagnostics/tests/generics/varProjection/setterNotProjectedOutAssign.fir.kt
new file mode 100644
index 00000000000..9086a1fa476
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/varProjection/setterNotProjectedOutAssign.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+// !WITH_NEW_INFERENCE
+interface Tr<T> {
+    var v: Tr<T>
+}
+
+fun test(t: Tr<*>) {
+    t.v = t
+    t.v checkType { <!UNRESOLVED_REFERENCE!>_<!><Tr<*>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutAssign.fir.kt b/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutAssign.fir.kt
new file mode 100644
index 00000000000..fedfb34f531
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutAssign.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNREACHABLE_CODE -UNUSED_PARAMETER
+// !CHECK_TYPE
+// !WITH_NEW_INFERENCE
+// t is unused due to KT-4233
+interface Tr<T> {
+    var v: T
+}
+
+fun test(t: Tr<*>) {
+    t.v = null!!
+    t.v = ""
+    t.v = null
+    t.v checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutNoPlusAssign.fir.kt b/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutNoPlusAssign.fir.kt
new file mode 100644
index 00000000000..48d011721fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutNoPlusAssign.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+// !WITH_NEW_INFERENCE
+interface Tr<T> {
+    var v: T
+}
+
+fun test(t: Tr<out String>) {
+    // resolved as t.v = t.v + null!!, where type of right operand is String,
+    // so TYPE_MISMATCH: String is not <: of Captured(out String)
+    t.v += null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutPlusAssignDefined.fir.kt b/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutPlusAssignDefined.fir.kt
new file mode 100644
index 00000000000..612031454d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutPlusAssignDefined.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+interface Tr<T> {
+    var v: T
+}
+
+class C {
+    operator fun plusAssign(c: C) {}
+}
+
+fun test(t: Tr<out C>) {
+    // No error because no real assignment happens
+    t.v += null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/generics/wildcardInValueParameter.fir.kt b/compiler/testData/diagnostics/tests/generics/wildcardInValueParameter.fir.kt
new file mode 100644
index 00000000000..4cb4e519fcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/wildcardInValueParameter.fir.kt
@@ -0,0 +1,14 @@
+// JAVAC_SKIP
+// FILE: JavaClass.java
+public class JavaClass {
+    public void foo(? x) {}
+
+    public void bar(? extends String y) { }
+}
+
+// FILE: main.kt
+fun foo() {
+    JavaClass().foo(Any())
+    JavaClass().<!INAPPLICABLE_CANDIDATE!>bar<!>(Any())
+    JavaClass().bar("")
+}
diff --git a/compiler/testData/diagnostics/tests/generics/wrongNumberOfTypeArgumentsDiagnostic.fir.kt b/compiler/testData/diagnostics/tests/generics/wrongNumberOfTypeArgumentsDiagnostic.fir.kt
new file mode 100644
index 00000000000..84e29cfaf8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/generics/wrongNumberOfTypeArgumentsDiagnostic.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+fun myFun(i : String) {}
+fun myFun(i : Int) {}
+
+fun test1() {
+    myFun<Int>(3)
+    <!INAPPLICABLE_CANDIDATE!>myFun<!><String>('a')
+}
+
+fun test2() {
+    val m0 = java.util.<!UNRESOLVED_REFERENCE!>HashMap<!>()
+    val m1 = java.util.<!UNRESOLVED_REFERENCE!>HashMap<!><String, String, String>()
+    val m2 = java.util.<!UNRESOLVED_REFERENCE!>HashMap<!><String>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/implicitIntersection.fir.kt b/compiler/testData/diagnostics/tests/implicitIntersection.fir.kt
new file mode 100644
index 00000000000..2877bb09372
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/implicitIntersection.fir.kt
@@ -0,0 +1,30 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+// See KT-10244: no intersection types in signatures
+
+open class B
+interface A
+interface C
+
+// Error!
+fun foo(b: B) = if (b is A && b is C) b else null
+
+// Ok: given explicitly
+fun gav(b: B): A? = if (b is A && b is C) b else null
+
+class My(b: B) {
+    // Error!
+    val x = if (b is A && b is C) b else null
+    // Ok: given explicitly
+    val y: C? = if (b is A && b is C) b else null
+    // Error!
+    fun foo(b: B) = if (b is A && b is C) b else null
+}
+
+fun bar(b: B): String {
+    // Ok: local variable
+    val tmp = if (b is A && b is C) b else null
+    // Error: local function
+    fun foo(b: B) = if (b is A && b is C) b else null
+    return tmp.toString()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/implicitNestedIntersection.fir.kt b/compiler/testData/diagnostics/tests/implicitNestedIntersection.fir.kt
new file mode 100644
index 00000000000..9a7ae4322b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/implicitNestedIntersection.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// NI_EXPECTED_FILE
+
+interface In<in E>
+open class A : In<A>
+open class B : In<B>
+
+fun <T> select(x: T, y: T) = x
+
+fun foo2() = select(A(), B()) // Type "In<A & B>" is prohibited in return position
+
+
+
+open class C : In<C>
+open class D : In<D>
+open class E : In<E>
+open class F : In<F>
+open class G : In<G>
+open class H : In<H>
+
+fun <S> select8(a: S, b: S, c: S, d: S, e: S, f: S, g: S, h: S) = a
+
+fun foo8() = select8(A(), B(), C(), D(), E(), F(), G(), H())
diff --git a/compiler/testData/diagnostics/tests/implicitNothing.fir.kt b/compiler/testData/diagnostics/tests/implicitNothing.fir.kt
new file mode 100644
index 00000000000..782f4576e60
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/implicitNothing.fir.kt
@@ -0,0 +1,52 @@
+fun foo() = throw Exception()
+
+fun bar() = null!!
+
+fun baz() = bar()
+
+fun gav(): Any = null!!
+
+val x = null!!
+
+val y: Nothing = throw Exception()
+
+fun check() {
+    // Error: KT-10449
+    fun local() = bar()
+    // Unreachable / unused, but not implicit Nothing
+    val x = null!!
+}
+
+fun nonLocalReturn() = run { return }
+
+class Klass {
+    fun bar() = null!!
+
+    val y = null!!
+
+    init {
+        fun local() = bar()
+        // Should be unreachable: see KT-5311
+        val z = null!!
+    }
+
+    fun foo() {
+        fun local() = bar()
+
+        val x = y
+    }
+}
+
+interface Base {
+    val x: Int
+
+    fun foo(): String
+}
+
+class Derived : Base {
+    // Ok for override
+    
+    override val x = null!!
+
+    override fun foo() = null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/AllUnderImportsAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/imports/AllUnderImportsAmbiguity.fir.kt
new file mode 100644
index 00000000000..3e478bc5576
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/AllUnderImportsAmbiguity.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a.kt
+package a
+
+class X
+
+// FILE: b.kt
+package b
+
+class X
+
+// FILE: c.kt
+package c
+
+import a.*
+import b.*
+
+class Y : X
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/AllUnderImportsLessPriority.fir.kt b/compiler/testData/diagnostics/tests/imports/AllUnderImportsLessPriority.fir.kt
new file mode 100644
index 00000000000..8b2c0dd0003
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/AllUnderImportsLessPriority.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a.kt
+package a
+
+open class X
+
+// FILE: b.kt
+package b
+
+class X
+
+// FILE: c.kt
+package c
+
+import a.X
+import b.*
+
+class Y : X()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/AllUnderImportsSamePriorityForFunction.fir.kt b/compiler/testData/diagnostics/tests/imports/AllUnderImportsSamePriorityForFunction.fir.kt
new file mode 100644
index 00000000000..6c9eb99bb8f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/AllUnderImportsSamePriorityForFunction.fir.kt
@@ -0,0 +1,19 @@
+// FILE: a.kt
+package a
+
+fun X(p: Int) {}
+
+// FILE: b.kt
+package b
+
+fun X(): Int = 1
+
+// FILE: c.kt
+package c
+
+import b.*
+import a.X
+
+fun foo() {
+    val v: Int = X()
+}
diff --git a/compiler/testData/diagnostics/tests/imports/AllUnderImportsSamePriorityForProperty.fir.kt b/compiler/testData/diagnostics/tests/imports/AllUnderImportsSamePriorityForProperty.fir.kt
new file mode 100644
index 00000000000..065aaebd11e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/AllUnderImportsSamePriorityForProperty.fir.kt
@@ -0,0 +1,19 @@
+// FILE: a.kt
+package a
+
+var X: Int = 1
+
+// FILE: b.kt
+package b
+
+var X: String = ""
+
+// FILE: c.kt
+package c
+
+import a.X
+import b.*
+
+fun foo() {
+    X = 1
+}
diff --git a/compiler/testData/diagnostics/tests/imports/CheckJavaVisibility.fir.kt b/compiler/testData/diagnostics/tests/imports/CheckJavaVisibility.fir.kt
new file mode 100644
index 00000000000..efae5022256
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/CheckJavaVisibility.fir.kt
@@ -0,0 +1,73 @@
+// FILE: j/JavaPublic.java
+package j;
+
+public class JavaPublic {
+    public static void javaM() {}
+    public static int javaP = 4;
+    static int javaPackageLocal = 5;
+}
+
+// FILE: j/JavaPackageLocal.java
+package j;
+
+class JavaPackageLocal {
+    static void javaMPackage() {}
+    static int javaPPackage = 4;
+}
+
+// FILE: j/JavaProtected.java
+package j;
+
+public class JavaProtected {
+    protected static void javaMProtected() {}
+    protected static int javaPProtected = 4;
+}
+
+// FILE: j/JavaPrivate.java
+package j;
+
+public class JavaPrivate {
+    private static void javaMPrivate() {}
+    private static int javaPPrivate = 4;
+}
+
+
+// FILE: k1.kt
+package k
+
+import j.JavaPublic
+import j.JavaPublic.javaM
+import j.JavaPublic.javaP
+import j.JavaPublic.javaPackageLocal
+
+import j.JavaPackageLocal
+import j.JavaPackageLocal.javaMPackage
+import j.JavaPackageLocal.javaPPackage
+
+import j.JavaProtected
+import j.JavaProtected.javaMProtected
+import j.JavaProtected.javaPProtected
+
+import j.JavaPrivate
+import j.JavaPrivate.javaMPrivate
+import j.JavaPrivate.javaPPrivate
+
+// FILE: k2.kt
+package j
+
+import j.JavaPublic
+import j.JavaPublic.javaM
+import j.JavaPublic.javaP
+import j.JavaPublic.javaPackageLocal
+
+import j.JavaPackageLocal
+import j.JavaPackageLocal.javaMPackage
+import j.JavaPackageLocal.javaPPackage
+
+import j.JavaProtected
+import j.JavaProtected.javaMProtected
+import j.JavaProtected.javaPProtected
+
+import j.JavaPrivate
+import j.JavaPrivate.javaMPrivate
+import j.JavaPrivate.javaPPrivate
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/CheckJavaVisibility2.fir.kt b/compiler/testData/diagnostics/tests/imports/CheckJavaVisibility2.fir.kt
new file mode 100644
index 00000000000..bd143fb16da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/CheckJavaVisibility2.fir.kt
@@ -0,0 +1,62 @@
+// FILE: j/JavaPackageLocal.java
+package j;
+
+public class JavaPackageLocal {
+    static void javaMPackage() {}
+    static int javaPPackage = 4;
+}
+
+// FILE: j/JavaProtected.java
+package j;
+
+public class JavaProtected {
+    protected static void javaMProtectedStatic() {}
+    protected static int javaPProtectedStatic = 4;
+    protected final int javaPProtectedPackage = 4;
+}
+
+// FILE: k.kt
+package k
+
+import j.JavaProtected
+import j.JavaPackageLocal
+
+class A {
+    val p1 = JavaPackageLocal.<!INAPPLICABLE_CANDIDATE!>javaPPackage<!>
+    val p2 = JavaProtected.<!INAPPLICABLE_CANDIDATE!>javaPProtectedStatic<!>
+    val p3 = JavaProtected().<!INAPPLICABLE_CANDIDATE!>javaPProtectedPackage<!>
+
+    fun test() {
+        JavaProtected.<!INAPPLICABLE_CANDIDATE!>javaMProtectedStatic<!>()
+        JavaPackageLocal.<!INAPPLICABLE_CANDIDATE!>javaMPackage<!>()
+    }
+}
+
+class B : JavaProtected() {
+    val p1 = JavaPackageLocal.<!INAPPLICABLE_CANDIDATE!>javaPPackage<!>
+    val p2 = JavaProtected.javaPProtectedStatic
+    val p3 = javaPProtectedPackage
+
+    fun test() {
+        JavaProtected.javaMProtectedStatic()
+        JavaPackageLocal.<!INAPPLICABLE_CANDIDATE!>javaMPackage<!>()
+    }
+}
+
+// FILE: j.kt
+package j
+
+import j.JavaProtected
+import j.JavaPackageLocal
+
+class C {
+    val p1 = JavaPackageLocal.javaPPackage
+    val p2 = JavaProtected.javaPProtectedStatic
+    val p3 = JavaProtected().javaPProtectedPackage
+
+    fun test() {
+        JavaProtected.javaMProtectedStatic()
+        JavaProtected.javaMProtectedStatic()
+        JavaPackageLocal.javaMPackage()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/CheckVisibility.fir.kt b/compiler/testData/diagnostics/tests/imports/CheckVisibility.fir.kt
new file mode 100644
index 00000000000..e7ceab762ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/CheckVisibility.fir.kt
@@ -0,0 +1,28 @@
+// MODULE: m1
+// FILE: k1.kt
+package k
+
+private class KPrivate
+internal class KInternal
+public class KPublic
+
+class A {
+    protected class KProtected
+}
+
+// FILE: k2.kt
+package k2
+
+import k.KPrivate
+import k.KInternal
+import k.KPublic
+import k.A.KProtected
+
+// MODULE: m2(m1)
+// FILE: k3.kt
+package k3
+
+import k.KPrivate
+import k.KInternal
+import k.KPublic
+import k.A.KProtected
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ClassClash.fir.kt b/compiler/testData/diagnostics/tests/imports/ClassClash.fir.kt
new file mode 100644
index 00000000000..810aea57d1b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ClassClash.fir.kt
@@ -0,0 +1,81 @@
+// MODULE: m1
+// FILE: a.kt
+package a
+
+class B {
+    fun m1() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+package a
+
+class B {
+    fun m2() {}
+}
+
+// MODULE: m3(m1, m2)
+// FILE: c.kt
+import a.B
+
+fun test(b: B) {
+    b.m1()
+    b.<!UNRESOLVED_REFERENCE!>m2<!>()
+
+    val b_: B = B()
+    b_.m1()
+
+    val b_1: a.B = B()
+    b_1.m1()
+
+    val b_2: B = a.B()
+    b_2.m1()
+
+    val b_3: B = B()
+    b_3.m1()
+
+    val b_4: B = a.B()
+    b_4.m1()
+}
+
+
+//----------------------------TOP LEVEL---------------------
+// MODULE: top_m1
+// FILE: top_a.kt
+class B {
+    fun m1() {}
+}
+
+// MODULE: top_m2
+// FILE: top_b.kt
+class B {
+    fun m2() {}
+}
+
+// MODULE: top_m3(top_m1, top_m2)
+// FILE: top_c.kt
+import B
+
+fun test(b: B) {
+    b.m1()
+    b.<!UNRESOLVED_REFERENCE!>m2<!>()
+
+    val b_: B = B()
+    b_.m1()
+
+    val b_2 = B()
+    b_2.m1()
+}
+
+// FILE: top_d.kt
+
+fun test2(b: B) {
+    b.m1()
+    b.<!UNRESOLVED_REFERENCE!>m2<!>()
+
+    val b_: B = B()
+    b_.m1()
+
+    val b_2 = B()
+    b_2.m1()
+}
diff --git a/compiler/testData/diagnostics/tests/imports/ClassClashStarImport.fir.kt b/compiler/testData/diagnostics/tests/imports/ClassClashStarImport.fir.kt
new file mode 100644
index 00000000000..73e0517a257
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ClassClashStarImport.fir.kt
@@ -0,0 +1,76 @@
+// !WITH_NEW_INFERENCE
+// MODULE: m1
+// FILE: a.kt
+package a
+
+class B {
+    fun m1() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+package a
+
+class B {
+    fun m2() {}
+}
+
+// MODULE: m3(m2, m1)
+// FILE: b.kt
+import a.*
+
+
+fun test(b: B) {
+    b.m2()
+    b.<!UNRESOLVED_REFERENCE!>m1<!>()
+
+    val b_: B = B()
+    b_.m2()
+
+    val b_1: a.B = B()
+    b_1.m2()
+
+    val b_2: B = a.B()
+    b_2.m2()
+
+    val b_3 = B()
+    b_3.m2()
+
+    val b_4 = a.B()
+    b_4.m2()
+}
+
+
+//----------------------------TOP LEVEL---------------------
+
+// MODULE: top_m1
+// FILE: top_a.kt
+class B {
+    fun m1() {}
+}
+
+// MODULE: top_m2
+// FILE: top_b.kt
+class B {
+    fun m2() {}
+}
+
+// MODULE: top_m3(top_m2, top_m1)
+// FILE: top_c.kt
+
+fun test(b: B) {
+    b.m2()
+    b.<!UNRESOLVED_REFERENCE!>m1<!>()
+
+    val b_: B = B()
+    b_.m2()
+
+    val b_2 = B()
+    b_2.m2()
+
+    val b_3 = B()
+    b_3.m2()
+
+    val b_4 = <!UNRESOLVED_REFERENCE!>a<!>.<!UNRESOLVED_REFERENCE!>B<!>()
+    b_4.<!UNRESOLVED_REFERENCE!>m2<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ClassImportsConflicting.fir.kt b/compiler/testData/diagnostics/tests/imports/ClassImportsConflicting.fir.kt
new file mode 100644
index 00000000000..a7c75219a9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ClassImportsConflicting.fir.kt
@@ -0,0 +1,15 @@
+//FILE:a.kt
+package a
+
+import b.O
+import c.O
+
+//FILE:b.kt
+package b
+
+object O {}
+
+//FILE:c.kt
+package c
+
+object O {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/CurrentPackageAndAllUnderImport.fir.kt b/compiler/testData/diagnostics/tests/imports/CurrentPackageAndAllUnderImport.fir.kt
new file mode 100644
index 00000000000..a9fe67145a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/CurrentPackageAndAllUnderImport.fir.kt
@@ -0,0 +1,16 @@
+// FILE: a.kt
+package a
+
+class X
+
+// FILE: b.kt
+package b
+
+open class X
+
+// FILE: b1.kt
+package b
+
+import a.*
+
+class Y : X() // class from the current package should take priority
diff --git a/compiler/testData/diagnostics/tests/imports/CurrentPackageAndExplicitImport.fir.kt b/compiler/testData/diagnostics/tests/imports/CurrentPackageAndExplicitImport.fir.kt
new file mode 100644
index 00000000000..75a66d31fdb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/CurrentPackageAndExplicitImport.fir.kt
@@ -0,0 +1,16 @@
+// FILE: a.kt
+package a
+
+open class Y
+
+// FILE: b.kt
+package b
+
+class X
+
+// FILE: b1.kt
+package b
+
+import a.Y as X
+
+class Y : X() // class from explicit import should take priority
diff --git a/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.fir.kt b/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.fir.kt
new file mode 100644
index 00000000000..dcd261d0336
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.fir.kt
@@ -0,0 +1,6 @@
+import java.lang.reflect.*
+import java.util.List
+
+fun foo(
+        p1: Array<String> /* should be resolved to kotlin.Array */,
+        p2: List<String> /* should be resolved to java.util.List */) { }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ExplicitImportsAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/imports/ExplicitImportsAmbiguity.fir.kt
new file mode 100644
index 00000000000..905fd270bb9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ExplicitImportsAmbiguity.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a.kt
+package a
+
+class X
+
+// FILE: b.kt
+package b
+
+class X
+
+// FILE: c.kt
+package c
+
+import a.X
+import b.X
+
+class Y : X
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ExplicitImportsUnambiguityForFunction.fir.kt b/compiler/testData/diagnostics/tests/imports/ExplicitImportsUnambiguityForFunction.fir.kt
new file mode 100644
index 00000000000..35903947784
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ExplicitImportsUnambiguityForFunction.fir.kt
@@ -0,0 +1,19 @@
+// FILE: a.kt
+package a
+
+fun X(p: Int) {}
+
+// FILE: b.kt
+package b
+
+fun X(): Int = 1
+
+// FILE: c.kt
+package c
+
+import b.X
+import a.X
+
+fun foo() {
+    val v: Int = X()
+}
diff --git a/compiler/testData/diagnostics/tests/imports/ExplicitPackageImportsAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/imports/ExplicitPackageImportsAmbiguity.fir.kt
new file mode 100644
index 00000000000..770dd1bcc1e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ExplicitPackageImportsAmbiguity.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a.kt
+package a.x
+
+class X
+
+// FILE: b.kt
+package b.x
+
+class X
+
+// FILE: c.kt
+package c
+
+import a.x
+import b.x
+
+class Y : x.X
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportClassClash.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportClassClash.fir.kt
new file mode 100644
index 00000000000..ecab6f23f24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportClassClash.fir.kt
@@ -0,0 +1,48 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: 1.kt
+package a
+
+class someFun() {}
+fun someFun(i: Int) {}
+
+class someVal() {}
+val Int.someVal: Int get() = 3
+
+class A
+
+class B
+
+// FILE: 2.kt
+package b
+
+class someFun
+class someVal
+class someAll
+
+fun A() {}
+
+class B
+
+
+// FILE: 3.kt
+import a.someFun
+import b.someFun
+
+import a.someVal
+import b.someVal
+
+import a.A
+import b.A
+
+// FILE: 4.kt
+import b.*
+import a.B
+
+// FILE: 5.kt
+package b
+
+import a.B
+
+// FILE: 6.kt
+import a.B
+import b.B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportFromCompanionObject.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportFromCompanionObject.fir.kt
new file mode 100644
index 00000000000..6c01868ec0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportFromCompanionObject.fir.kt
@@ -0,0 +1,138 @@
+// FILE: a.kt
+package a
+
+class C1 {
+    companion object O {
+        class A
+        object B
+
+        fun bar() {}
+    }
+}
+
+
+class C2 {
+    companion object S {
+
+        val prop: String = ""
+
+        fun o(s: String) = Unit
+        fun o(i: Int) = Unit
+
+        fun Int.ext() = Unit
+        var String.ext: Int
+            get() = 3
+            set(i) {
+            }
+
+        fun A(c: Int) = A()
+
+        class A()
+
+        fun <T> genericFun(t: T, t2: T): T = t
+    }
+}
+
+open class Base {
+    fun f() {
+    }
+
+    fun <T> g(t: T) {
+    }
+
+    val p = 1
+    val Int.ext: Int
+        get() = 4
+}
+
+interface BaseI<T> {
+    fun fromI(): Int = 3
+
+    fun genericFromI(t: T) = t
+}
+
+class C3 {
+    companion object K: Base(), BaseI<Int> {
+        val own: String = ""
+    }
+}
+
+// FILE: b.kt
+package b
+
+import a.C1.O.*
+
+fun testErroneusAllUnderImportFromObject() {
+    A()
+    B
+    bar()
+}
+
+// FILE: c.kt
+package c
+
+import a.C2.S.prop
+import a.C2.S.o
+import a.C2.S.ext
+import a.C2.S.A
+import a.C2.S.genericFun
+import a.C2.S.ext as extRenamed
+
+fun testImportFromObjectByName() {
+    prop
+    o("a")
+    o(3)
+    3.ext()
+    "".ext = 3
+    val c: Int = "".ext
+
+    3.extRenamed()
+    "".extRenamed = 3
+    val c2: Int = "".extRenamed
+
+    A()
+    A(3)
+
+    val a: Int = genericFun(3, 3)
+    val s: String = genericFun("A", "b")
+    val b: Boolean = genericFun(true, false)
+}
+
+fun <T> t(t: T): T {
+    return genericFun(t, t)
+}
+
+// FILE: d.kt
+package d
+
+import a.C2.S.prop as renamed
+
+fun testFunImportedFromObjectHasNoDispatchReceiver(l: a.C2.S) {
+    l.<!UNRESOLVED_REFERENCE!>renamed<!>
+    l.prop
+    renamed
+}
+
+// FILE: e.kt
+
+package e
+
+import a.C3.K.f
+import a.C3.K.g
+import a.C3.K.p
+import a.C3.K.own
+import a.C3.K.fromI
+import a.C3.K.genericFromI
+import a.C3.K.ext
+
+fun testMembersFromSupertypes() {
+    f()
+    g("")
+    p
+    fromI()
+
+    genericFromI(3)
+    <!INAPPLICABLE_CANDIDATE!>genericFromI<!>("a")
+
+    own
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportFromCurrentWithDifferentName.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportFromCurrentWithDifferentName.fir.kt
new file mode 100644
index 00000000000..08d4242283a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportFromCurrentWithDifferentName.fir.kt
@@ -0,0 +1,8 @@
+package a
+
+import a.A as ER
+
+interface A {
+    val a: A
+    val b: ER
+}
diff --git a/compiler/testData/diagnostics/tests/imports/ImportFromObject.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportFromObject.fir.kt
new file mode 100644
index 00000000000..8da9103fbc1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportFromObject.fir.kt
@@ -0,0 +1,132 @@
+// FILE: a.kt
+package a
+
+object O {
+    class A
+    object B
+
+    fun bar() {}
+}
+
+
+object S {
+
+    val prop: String = ""
+
+    fun o(s: String) = Unit
+    fun o(i: Int) = Unit
+
+    fun Int.ext() = Unit
+    var String.ext: Int
+        get() = 3
+        set(i) {
+        }
+
+    fun A(c: Int) = A()
+
+    class A()
+
+    fun <T> genericFun(t: T, t2: T): T = t
+}
+
+open class Base {
+    fun f() {
+    }
+
+    fun <T> g(t: T) {
+    }
+
+    val p = 1
+    val Int.ext: Int
+        get() = 4
+}
+
+interface BaseI<T> {
+    fun fromI(): Int = 3
+
+    fun genericFromI(t: T) = t
+}
+
+object K: Base(), BaseI<Int> {
+    val own: String = ""
+}
+
+// FILE: b.kt
+package b
+
+import a.O.*
+
+fun testErroneusAllUnderImportFromObject() {
+    A()
+    B
+    bar()
+}
+
+// FILE: c.kt
+package c
+
+import a.S.prop
+import a.S.o
+import a.S.ext
+import a.S.A
+import a.S.genericFun
+import a.S.ext as extRenamed
+
+fun testImportFromObjectByName() {
+    prop
+    o("a")
+    o(3)
+    3.ext()
+    "".ext = 3
+    val c: Int = "".ext
+
+    3.extRenamed()
+    "".extRenamed = 3
+    val c2: Int = "".extRenamed
+
+    A()
+    A(3)
+
+    val a: Int = genericFun(3, 3)
+    val s: String = genericFun("A", "b")
+    val b: Boolean = genericFun(true, false)
+}
+
+fun <T> t(t: T): T {
+    return genericFun(t, t)
+}
+
+// FILE: d.kt
+package d
+
+import a.S.prop as renamed
+
+fun testFunImportedFromObjectHasNoDispatchReceiver(l: a.S) {
+    l.<!UNRESOLVED_REFERENCE!>renamed<!>
+    l.prop
+    renamed
+}
+
+// FILE: e.kt
+
+package e
+
+import a.K.f
+import a.K.g
+import a.K.p
+import a.K.own
+import a.K.fromI
+import a.K.genericFromI
+import a.K.ext
+
+fun testMembersFromSupertypes() {
+    f()
+    g("")
+    p
+    fromI()
+
+    genericFromI(3)
+    <!INAPPLICABLE_CANDIDATE!>genericFromI<!>("a")
+
+    own
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportFromRootPackage.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportFromRootPackage.fir.kt
new file mode 100644
index 00000000000..1c31f98ab46
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportFromRootPackage.fir.kt
@@ -0,0 +1,32 @@
+// FILE: rootPackage.kt
+class Klass {
+    class Nested
+}
+
+class NotImported
+
+fun function() = ""
+
+val property = ""
+
+// FILE: anotherFromRootPackage.kt
+fun foo(): Klass {
+    function() + property
+    return Klass()
+}
+
+// FILE: anotherFromRootPackage.kt
+package pkg
+
+import Klass
+import Klass.Nested
+import function
+import property
+
+fun foo(): Klass {
+    function() + property
+    return Klass()
+}
+
+val v: Nested = Nested()
+val x: NotImported = <!UNRESOLVED_REFERENCE!>NotImported<!>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportHidingDefinitionInTheSameFile.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportHidingDefinitionInTheSameFile.fir.kt
new file mode 100644
index 00000000000..3f3a6226ebc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportHidingDefinitionInTheSameFile.fir.kt
@@ -0,0 +1,9 @@
+// ResolveSession.resolveToDescriptor used to crash on such code, so we just check that it's ok now
+import kotlin.Double
+import kotlin.collections.List
+import kotlin.arrayOfNulls
+
+class List {}
+
+fun arrayOfNulls(){}
+val arrayOfNulls: Int = 0
diff --git a/compiler/testData/diagnostics/tests/imports/ImportNestedWithDifferentName.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportNestedWithDifferentName.fir.kt
new file mode 100644
index 00000000000..f5d156292aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportNestedWithDifferentName.fir.kt
@@ -0,0 +1,10 @@
+package a
+
+import a.A.Nested as X
+
+interface A {
+    class Nested
+
+    val a: Nested
+    val b: X
+}
diff --git a/compiler/testData/diagnostics/tests/imports/ImportObjectAndUseAsSupertype.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportObjectAndUseAsSupertype.fir.kt
new file mode 100644
index 00000000000..4b4b9306d5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportObjectAndUseAsSupertype.fir.kt
@@ -0,0 +1,19 @@
+// FILE: a.kt
+
+package foo
+
+object Bar {
+    fun bar() {}
+}
+
+// FILE: b.kt
+
+package baz
+
+import foo.Bar
+
+class C: Bar
+
+fun test() {
+    Bar.bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportObjectHidesCurrentPackage.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportObjectHidesCurrentPackage.fir.kt
new file mode 100644
index 00000000000..677f6f9f383
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportObjectHidesCurrentPackage.fir.kt
@@ -0,0 +1,12 @@
+//FILE:a.kt
+package a
+
+// no error is reported
+import b.a
+
+fun foo() = a
+
+//FILE:b.kt
+package b
+
+object a {}
diff --git a/compiler/testData/diagnostics/tests/imports/ImportOverloadFunctions.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportOverloadFunctions.fir.kt
new file mode 100644
index 00000000000..9e93dd8d3d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportOverloadFunctions.fir.kt
@@ -0,0 +1,45 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// FILE: 1.kt
+package k
+
+private fun zero() {}
+private fun zero(a: Int) {}
+private fun zero(a: String) {}
+
+fun one() {}
+private fun one(a: Int) {}
+private fun one(a: String) {}
+
+fun two() {}
+fun two(a: Int) {}
+private fun two(a: String) {}
+
+fun all() {}
+fun all(a: Int) {}
+fun all(a: String) {}
+
+// FILE: 2.kt
+
+import k.zero
+import k.one
+import k.two
+import k.all
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>zero<!>()
+    <!INAPPLICABLE_CANDIDATE!>zero<!>(1)
+    <!INAPPLICABLE_CANDIDATE!>zero<!>("")
+
+    one()
+    <!INAPPLICABLE_CANDIDATE!>one<!>(1)
+    <!INAPPLICABLE_CANDIDATE!>one<!>("")
+
+    two()
+    two(1)
+    <!INAPPLICABLE_CANDIDATE!>two<!>("")
+
+    all()
+    all(1)
+    all("")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportPrivateMember.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportPrivateMember.fir.kt
new file mode 100644
index 00000000000..434a8a9cf82
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportPrivateMember.fir.kt
@@ -0,0 +1,37 @@
+package test
+
+import test.TopLevelClass.NestedClass
+import test.TopLevelClass.NestedClass.InNested
+import test.TopLevelEnum.NestedEnum.NestedEntry
+import test.TopLevelObject.inObject
+import test.TopLevelEnum.E1
+
+private class TopLevelClass {
+    private class NestedClass {
+        class InNested
+    }
+
+    fun test() {
+        InNested()
+    }
+}
+
+private enum class TopLevelEnum(private val e: NestedEnum) {
+    E1(NestedEntry);
+
+    private enum class NestedEnum {
+        NestedEntry;
+    }
+}
+
+private object TopLevelObject {
+    fun inObject() {}
+}
+
+fun testAccess() {
+    <!INAPPLICABLE_CANDIDATE!>NestedClass<!>()
+    E1
+    InNested()
+    NestedEntry
+    inObject()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportPrivateMemberFromOtherFile.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportPrivateMemberFromOtherFile.fir.kt
new file mode 100644
index 00000000000..af6f1c5e93f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportPrivateMemberFromOtherFile.fir.kt
@@ -0,0 +1,26 @@
+// FILE: A.kt
+
+class A {
+    private class Nested {
+        object O1
+    }
+}
+
+// FILE: B.java
+
+public class B {
+    private static class JC {
+        public static class JC1 {
+        }
+    }
+}
+
+// FILE: C.kt
+
+import A.Nested.*
+import B.JC.JC1
+
+fun test() {
+    O1
+    JC1()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportPrivateMembersWithStar.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportPrivateMembersWithStar.fir.kt
new file mode 100644
index 00000000000..ca8d7b91a77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportPrivateMembersWithStar.fir.kt
@@ -0,0 +1,32 @@
+package test
+
+import test.TopLevelClass.NestedClass.*
+import test.TopLevelEnum.NestedEnum.*
+import test.TopLevelEnum.*
+
+private class TopLevelClass {
+    private class NestedClass {
+        class A1
+        object A2
+    }
+
+    fun test() {
+        A1()
+        A2
+    }
+}
+
+private enum class TopLevelEnum(private val e: NestedEnum) {
+    E1(NestedEntry);
+
+    private enum class NestedEnum {
+        NestedEntry;
+    }
+}
+
+fun testAccess() {
+    E1
+    NestedEntry
+    A1()
+    A2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportProtectedClass.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportProtectedClass.fir.kt
new file mode 100644
index 00000000000..bad5d7c283b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportProtectedClass.fir.kt
@@ -0,0 +1,14 @@
+package p
+
+import p.Foo.Nested
+
+open class Foo {
+    protected class Nested
+}
+
+class Bar: Foo() {
+    protected fun foo(): Nested? = null
+}
+
+private fun foo(): Nested? = null
+private fun bar(): p.Foo.Nested? = null
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportResolutionOrder.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportResolutionOrder.fir.kt
new file mode 100644
index 00000000000..d93874eb976
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportResolutionOrder.fir.kt
@@ -0,0 +1,23 @@
+// FILE: b.kt
+// KT-355 Resolve imports after all symbols are built
+
+package a
+  import b.*
+  val x : X = X()
+
+// FILE: b.kt
+package b
+  class X() {
+
+  }
+
+// FILE: b.kt
+package c
+  import d.X
+  val x : X = X()
+
+// FILE: b.kt
+package d
+  class X() {
+
+  }
diff --git a/compiler/testData/diagnostics/tests/imports/ImportTwoTimes.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportTwoTimes.fir.kt
new file mode 100644
index 00000000000..75aba1ca39c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportTwoTimes.fir.kt
@@ -0,0 +1,14 @@
+// FILE: a.kt
+
+package weatherForecast
+
+fun weatherToday() = "snow"
+
+// FILE: b.kt
+
+package myApp
+
+import weatherForecast.weatherToday
+import weatherForecast.weatherToday
+
+fun needUmbrella() = weatherToday() == "rain"
diff --git a/compiler/testData/diagnostics/tests/imports/ImportTwoTimesStar.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportTwoTimesStar.fir.kt
new file mode 100644
index 00000000000..83e6d3f3e28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportTwoTimesStar.fir.kt
@@ -0,0 +1,14 @@
+// FILE: a.kt
+
+package weatherForecast
+
+fun weatherToday() = "snow"
+
+// FILE: b.kt
+
+package myApp
+
+import weatherForecast.*
+import weatherForecast.*
+
+fun needUmbrella() = weatherToday() == "rain"
diff --git a/compiler/testData/diagnostics/tests/imports/Imports.fir.kt b/compiler/testData/diagnostics/tests/imports/Imports.fir.kt
new file mode 100644
index 00000000000..e0d485a9252
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/Imports.fir.kt
@@ -0,0 +1,102 @@
+// !WITH_NEW_INFERENCE
+// FILE:a.kt
+package a
+
+import b.B        //class
+import b.foo      //function
+import b.ext      //extension function
+import b.value    //property
+import b.C.Companion.bar    //function from companion object
+import b.C.Companion.cValue //property from companion object
+import b.constant.fff     //function from val
+import b.constant.dValue  //property from val
+import b.constant
+import b.E.Companion.f      //val from companion object
+import smth.illegal
+import b.C.smth.illegal
+import b.bar.smth
+import b.bar.*
+import b.unr.unr.unr
+import unr.unr.unr
+
+fun test(arg: B) {
+    foo(value)
+    arg.ext()
+
+    bar()
+    foo(cValue)
+
+    <!UNRESOLVED_REFERENCE!>fff<!>(<!UNRESOLVED_REFERENCE!>dValue<!>)
+
+    constant.fff(constant.dValue)
+
+    f.f()
+}
+
+// FILE:b.kt
+package b
+
+class B() {}
+
+fun foo(i: Int) = i
+
+fun B.ext() {}
+
+val value = 0
+
+class C() {
+    companion object {
+        fun bar() {}
+        val cValue = 1
+    }
+}
+
+class D() {
+    fun fff(s: String) = s
+    val dValue = "w"
+}
+
+val constant = D()
+
+class E() {
+    companion object {
+        val f = F()
+    }
+}
+
+class F() {
+    fun f() {}
+}
+
+fun bar() {}
+
+//FILE:c.kt
+package c
+
+import c.C.*
+
+object C {
+    fun f() {
+    }
+    val i = 348
+}
+
+fun foo() {
+    if (i == 3) f()
+}
+
+//FILE:d.kt
+package d
+
+import d.A.Companion.B
+import d.A.Companion.C
+
+val b : B = B()
+val c : B = C
+
+class A() {
+    companion object {
+        open class B() {}
+        object C : B() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/ImportsConflicting.fir.kt b/compiler/testData/diagnostics/tests/imports/ImportsConflicting.fir.kt
new file mode 100644
index 00000000000..32368bda9c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/ImportsConflicting.fir.kt
@@ -0,0 +1,15 @@
+//FILE:a.kt
+package a
+
+import b.foo
+import c.foo // TODO: need warning here
+
+//FILE:b.kt
+package b
+
+fun foo() = 2
+
+//FILE:c.kt
+package c
+
+fun foo() = 1
diff --git a/compiler/testData/diagnostics/tests/imports/InaccessiblePrivateClass.fir.kt b/compiler/testData/diagnostics/tests/imports/InaccessiblePrivateClass.fir.kt
new file mode 100644
index 00000000000..5a7a9668d1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/InaccessiblePrivateClass.fir.kt
@@ -0,0 +1,18 @@
+// FILE: a.kt
+package p1
+
+private class X
+private class Y
+
+// FILE: b.kt
+package p2
+
+class X
+
+// FILE: c.kt
+package p1
+
+import p2.*
+
+val x: X = X()
+val y: Y = <!INAPPLICABLE_CANDIDATE!>Y<!>()
diff --git a/compiler/testData/diagnostics/tests/imports/JavaPackageLocalClassNotImported.fir.kt b/compiler/testData/diagnostics/tests/imports/JavaPackageLocalClassNotImported.fir.kt
new file mode 100644
index 00000000000..db191bd4cda
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/JavaPackageLocalClassNotImported.fir.kt
@@ -0,0 +1,12 @@
+// FILE: File.kt
+package pack
+
+public open class InetAddressImpl
+
+// FILE: Main.kt
+package a
+
+import java.net.* // should not import java.net.InetAddressImpl because it's package local
+import pack.*
+
+class X : <!UNRESOLVED_REFERENCE!>InetAddressImpl<!>() // should resolve to our pack.InetAddressImpl
diff --git a/compiler/testData/diagnostics/tests/imports/MalformedImports.fir.kt b/compiler/testData/diagnostics/tests/imports/MalformedImports.fir.kt
new file mode 100644
index 00000000000..9b3737637de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/MalformedImports.fir.kt
@@ -0,0 +1,9 @@
+package test
+
+import some.<!SYNTAX!><!>
+import <!SYNTAX!>.some<!>
+import <!SYNTAX!>.kotlin<!>
+import kotlin.<!SYNTAX!><!>
+import<!SYNTAX!><!>
+import <!SYNTAX!>.<!>
+import <!SYNTAX!>*<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/NestedClassClash.fir.kt b/compiler/testData/diagnostics/tests/imports/NestedClassClash.fir.kt
new file mode 100644
index 00000000000..520a6fd70bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/NestedClassClash.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: a.kt
+package a
+
+class A {
+    class B
+}
+
+// FILE: b.kt
+package a
+
+class D {
+    class B
+}
+
+// FILE: c.kt
+import a.A.B
+import a.D.B
+
+fun test(b: B) {
+    B()
+}
+
+// FILE: d.kt
+import a.A.*
+import a.D.*
+
+// todo ambiguvity here
+fun test2(b: B) {
+    B()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/OperatorRenameOnImport.fir.kt b/compiler/testData/diagnostics/tests/imports/OperatorRenameOnImport.fir.kt
new file mode 100644
index 00000000000..46466062ea0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/OperatorRenameOnImport.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: a.kt
+package a
+
+interface A
+
+operator fun A.plus(other: A): A = this
+
+// FILE: b.kt
+package b
+
+import a.A
+import a.plus as minus
+
+fun test(a1: A, a2: A) =
+        a1 - a2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/PackageLocalClassNotImported.fir.kt b/compiler/testData/diagnostics/tests/imports/PackageLocalClassNotImported.fir.kt
new file mode 100644
index 00000000000..bea3b640a56
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/PackageLocalClassNotImported.fir.kt
@@ -0,0 +1,17 @@
+// FILE: File1.kt
+package pack1
+
+private class SomeClass
+
+// FILE: File2.kt
+package pack2
+
+public open class SomeClass
+
+// FILE: Main.kt
+package a
+
+import pack1.*
+import pack2.*
+
+class X : <!INAPPLICABLE_CANDIDATE!>SomeClass<!>()
diff --git a/compiler/testData/diagnostics/tests/imports/PackageLocalClassReferencedError.fir.kt b/compiler/testData/diagnostics/tests/imports/PackageLocalClassReferencedError.fir.kt
new file mode 100644
index 00000000000..20803950834
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/PackageLocalClassReferencedError.fir.kt
@@ -0,0 +1,11 @@
+// FILE: File1.kt
+package pack1
+
+private open class SomeClass
+
+// FILE: Main.kt
+package a
+
+import pack1.*
+
+private class X : <!INAPPLICABLE_CANDIDATE!>SomeClass<!>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/PackageVsClass.fir.kt b/compiler/testData/diagnostics/tests/imports/PackageVsClass.fir.kt
new file mode 100644
index 00000000000..a333f14b679
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/PackageVsClass.fir.kt
@@ -0,0 +1,152 @@
+// MODULE: m1
+// FILE: a.kt
+package a.b
+
+fun ab_fun() {}
+
+class c {
+    fun ab_c() {}
+
+    class d {
+        fun ab_cd() {}
+    }
+}
+
+// MODULE: m2
+// FILE: b.kt
+package a
+
+fun a_fun() {}
+
+class b {
+    fun a_b() {}
+
+    class c {
+        fun a_bc() {}
+    }
+}
+
+// MODULE: m3(m1, m2)
+// FILE: c.kt
+import a.a_fun
+import a.b
+
+import a.b.ab_fun
+import a.b.c
+
+fun test(a_b: b) {
+    a_b.a_b()
+
+    val a_bc: b.c = b.c()
+    a_bc.a_bc()
+
+    val a_bc2 = b.c()
+    a_bc2.a_bc()
+
+    a_fun()
+}
+
+fun test2(ab_c: c) {
+    ab_c.ab_c()
+
+    val ab_cd: c.d = c.d()
+    ab_cd.ab_cd()
+
+    val ab_cd2 = c.d()
+    ab_cd2.ab_cd()
+
+    ab_fun()
+}
+
+// FILE: d.kt
+package a
+
+import a.b.ab_fun
+import a.b.c
+
+fun test(a_b: b) {
+    a_b.a_b()
+
+    val a_bc: b.c = b.c()
+    a_bc.a_bc()
+
+    val a_bc2 = b.c()
+    a_bc2.a_bc()
+
+    a_fun()
+}
+
+fun test2(ab_c: c) {
+    ab_c.ab_c()
+
+    val ab_cd: c.d = c.d()
+    ab_cd.ab_cd()
+
+    val ab_cd2 = c.d()
+    ab_cd2.ab_cd()
+
+    ab_fun()
+}
+
+//---- Changed dependence order
+// MODULE: m4(m2, m1)
+// FILE: c.kt
+import a.a_fun
+import a.b
+
+import a.b.ab_fun
+import a.b.c
+
+fun test(a_b: b) {
+    a_b.a_b()
+
+    val a_bc: b.c = b.c()
+    a_bc.a_bc()
+
+    val a_bc2 = b.c()
+    a_bc2.a_bc()
+
+    a_fun()
+}
+
+fun test2(ab_c: c) {
+    ab_c.ab_c()
+
+    val ab_cd: c.d = c.d()
+    ab_cd.ab_cd()
+
+    val ab_cd2 = c.d()
+    ab_cd2.ab_cd()
+
+    ab_fun()
+}
+
+// FILE: d.kt
+package a
+
+import a.b.ab_fun
+import a.b.c
+
+fun test(a_b: b) {
+    a_b.a_b()
+
+    val a_bc: b.c = b.c()
+    a_bc.a_bc()
+
+    val a_bc2 = b.c()
+    a_bc2.a_bc()
+
+    a_fun()
+}
+
+fun test2(ab_c: c) {
+    ab_c.ab_c()
+
+    val ab_cd: c.d = c.d()
+    ab_cd.ab_cd()
+
+    val ab_cd2 = c.d()
+    ab_cd2.ab_cd()
+
+    ab_fun()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/PrivateClassNotImported.fir.kt b/compiler/testData/diagnostics/tests/imports/PrivateClassNotImported.fir.kt
new file mode 100644
index 00000000000..7510fdfe1bd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/PrivateClassNotImported.fir.kt
@@ -0,0 +1,21 @@
+// FILE: File1.kt
+package pack1
+
+public class SomeClass {
+    private class N
+    public open class PublicNested
+}
+
+// FILE: File2.kt
+package pack2
+
+public open class N
+
+// FILE: Main.kt
+package a
+
+import pack1.SomeClass.*
+import pack2.*
+
+class X : <!INAPPLICABLE_CANDIDATE!>N<!>()
+class Y : PublicNested()
diff --git a/compiler/testData/diagnostics/tests/imports/PrivateClassReferencedError.fir.kt b/compiler/testData/diagnostics/tests/imports/PrivateClassReferencedError.fir.kt
new file mode 100644
index 00000000000..a6fda12428f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/PrivateClassReferencedError.fir.kt
@@ -0,0 +1,14 @@
+// FILE: File1.kt
+package pack1
+
+public class SomeClass {
+    private class N
+    public open class PublicNested
+}
+
+// FILE: Main.kt
+package a
+
+import pack1.SomeClass.*
+
+private class X : <!INAPPLICABLE_CANDIDATE!>N<!>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/RenameOnImport.fir.kt b/compiler/testData/diagnostics/tests/imports/RenameOnImport.fir.kt
new file mode 100644
index 00000000000..7e82d721032
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/RenameOnImport.fir.kt
@@ -0,0 +1,22 @@
+// FILE: a.kt
+package a
+
+val x = 1
+val y = 1
+
+// FILE: b.kt
+package b
+
+val x = ""
+
+// FILE: c.kt
+package c
+
+import a.x as AX
+import a.*
+import b.*
+import a.y as AY
+
+val v1: Int = AX
+val v2: String = <!AMBIGUITY!>x<!>
+val v3 = y
diff --git a/compiler/testData/diagnostics/tests/imports/StarImportFromObject.fir.kt b/compiler/testData/diagnostics/tests/imports/StarImportFromObject.fir.kt
new file mode 100644
index 00000000000..8302d8698ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/StarImportFromObject.fir.kt
@@ -0,0 +1,47 @@
+package a
+
+import a.A.*
+import a.A.C
+import a.A.C.*
+import a.A.D.*
+import a.A.C.*
+import a.A.C.G
+import a.A.E.J.*
+import a.A.CO.*
+import a.A.CO
+
+import a.B.C.*
+import a.B.C.A.*
+import a.B.C.D.*
+
+import a.E.*
+import a.E.E1
+import a.E.E2.*
+
+class A {
+    object C {
+        object G
+    }
+    object D {
+
+    }
+
+    class E {
+        object J
+    }
+
+    companion object CO {
+        object H
+    }
+}
+
+enum class E {
+    E1, E2
+}
+
+object B {
+    class C {
+        object A
+        object D
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/SyntaxError.fir.kt b/compiler/testData/diagnostics/tests/imports/SyntaxError.fir.kt
new file mode 100644
index 00000000000..1dd3c4ec94c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/SyntaxError.fir.kt
@@ -0,0 +1,60 @@
+// FILE:a.kt
+package a
+
+val foo = 2
+fun bar() {}
+
+class B {
+    val foo = 2
+    fun bar() {}
+
+    class C
+}
+
+// FILE:b.kt
+package a.b.c
+
+class D {
+    class E {
+
+    }
+}
+
+
+// FILE:c.kt
+import<!SYNTAX!><!> ;
+import <!SYNTAX!>.<!>
+import a.<!SYNTAX!><!> ;
+import <!SYNTAX!>.a.<!> ;
+import <!SYNTAX!>.a.b<!> ;
+import <!SYNTAX!>.a.B<!> ;
+import a.B.<!SYNTAX!><!> ;
+import a.B.C.<!SYNTAX!><!> ;
+import a.B.foo.<!SYNTAX!><!> ;
+import a.B.bar.<!SYNTAX!><!> ;
+import a.b.<!SYNTAX!><!> ;
+import a.b.c.<!SYNTAX!><!> ;
+import a.<!SYNTAX!>%<!>.b.c.<!SYNTAX!><!> ;
+import a.b.c.D.<!SYNTAX!><!> ;
+import a.b.c.D.E.<!SYNTAX!><!> ;
+
+// FILE:d.kt
+import<!SYNTAX!><!>
+import <!SYNTAX!>.<!>
+import a.<!SYNTAX!><!>
+import <!SYNTAX!>.a.<!>
+import <!SYNTAX!>.a.b<!>
+import <!SYNTAX!>.a.B<!>
+import a.B.<!SYNTAX!><!> as<!SYNTAX!><!>
+import a.B.<!SYNTAX!><!> as A
+import a.B.<!SYNTAX!><!>
+import a.B.C.<!SYNTAX!><!>
+import a.B.foo.<!SYNTAX!><!>
+import a.B.bar.<!SYNTAX!><!>
+import a.b.<!SYNTAX!><!>
+import a.b.c.<!SYNTAX!><!>
+import a.<!SYNTAX!>%<!>.b.c.<!SYNTAX!><!>
+import a.b.c.D.<!SYNTAX!><!>
+import a.b.c.D.E.<!SYNTAX!><!>
+
+import a<!SYNTAX!>?.<!><!SYNTAX!>b<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/TopLevelClassVsPackage.fir.kt b/compiler/testData/diagnostics/tests/imports/TopLevelClassVsPackage.fir.kt
new file mode 100644
index 00000000000..4317d323edc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/TopLevelClassVsPackage.fir.kt
@@ -0,0 +1,68 @@
+// MODULE: m1
+// FILE: a.kt
+package a
+
+fun a_fun() {}
+
+class b {
+    fun a_b() {}
+
+    class c {
+        fun a_bc() {}
+    }
+}
+
+// MODULE: m2
+// FILE: b.kt
+fun _fun() {}
+
+class a {
+    fun _a() {}
+
+    class b {
+        fun _ab() {}
+    }
+}
+
+// MODULE: m3(m1, m2)
+// FILE: c.kt
+import a.a_fun
+import a.b
+
+fun test(a_b: b) {
+    a_b.a_b()
+
+    val a_bc: b.c = b.c()
+    a_bc.a_bc()
+
+    a_fun()
+}
+
+// FILE: d.kt
+fun test2(_a: a) {
+    _a._a()
+
+    val _ab: a.b = a.b()
+    _ab._ab()
+
+    val _ab2 = a.b()
+    _ab2._ab()
+
+    _fun()
+}
+
+// FILE: e.kt
+import a
+import _fun
+
+fun test3(_a: a) {
+    _a._a()
+
+    val _ab: a.b = a.b()
+    _ab._ab()
+
+    val _ab2 = a.b()
+    _ab2._ab()
+
+    _fun()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/WrongImport.fir.kt b/compiler/testData/diagnostics/tests/imports/WrongImport.fir.kt
new file mode 100644
index 00000000000..5cd8ecce24e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/WrongImport.fir.kt
@@ -0,0 +1,78 @@
+// FILE:a.kt
+package a.b
+
+// FILE:a.kt
+package a
+
+val foo = object {
+    fun bar() {}
+}
+
+fun bar() = object {
+    val foo = 239
+}
+
+class B {
+    val foo = object {
+        fun bar() {}
+    }
+
+    fun bar() = object {
+        val foo = 239
+    }
+}
+
+object C {
+    val foo = object {
+        fun bar() {}
+    }
+
+    fun bar() = object {
+        val foo = 239
+    }
+
+    class Nested
+}
+
+class D {
+    companion object {
+        val foo = object {
+            fun bar() {}
+        }
+
+        fun bar() = object {
+            val foo = 239
+        }
+    }
+}
+
+
+// FILE:b.kt
+import a
+import a.b
+
+import a.foo
+import a.foo.bar
+import a.bar
+import a.bar.foo
+
+import a.B.foo
+import a.B.foo.bar
+import a.B.bar
+import a.B.bar.foo
+
+import a.C.foo
+import a.C.foo.bar
+import a.C.bar
+import a.C.bar.foo
+import a.C.Nested
+
+import a.D.foo
+import a.D.foo.bar
+import a.D.bar
+import a.D.bar.foo
+
+import a.D.Companion.foo
+import a.D.Companion.foo.bar
+import a.D.Companion.bar
+import a.D.Companion.bar.foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/importFunctionWithAllUnderImport.fir.kt b/compiler/testData/diagnostics/tests/imports/importFunctionWithAllUnderImport.fir.kt
new file mode 100644
index 00000000000..3fd65fd6d42
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/importFunctionWithAllUnderImport.fir.kt
@@ -0,0 +1,13 @@
+// FILE: importFunctionWithAllUnderImport.kt
+package test
+
+import testOther.*
+
+class B: A()
+val inferTypeFromImportedFun = testFun()
+
+// FILE: importFunctionWithAllUnderImportOther.kt
+package testOther
+
+open class A
+fun testFun() = 1
diff --git a/compiler/testData/diagnostics/tests/imports/importFunctionWithAllUnderImportAfterNamedImport.fir.kt b/compiler/testData/diagnostics/tests/imports/importFunctionWithAllUnderImportAfterNamedImport.fir.kt
new file mode 100644
index 00000000000..d5f7005f3bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/importFunctionWithAllUnderImportAfterNamedImport.fir.kt
@@ -0,0 +1,22 @@
+//FILE:mainFile.kt
+//----------------------------------------------------------------------------------
+package test
+
+import testing.other.*
+import testing.TestFun
+
+// Resolve shouldn't be ambiguous
+val a = TestFun()
+
+
+//FILE:testing.kt
+//----------------------------------------------------------------------------------
+package testing
+
+class TestFun
+
+//FILE:testingOther.kt
+//----------------------------------------------------------------------------------
+package testing.other
+
+fun TestFun() = 12
diff --git a/compiler/testData/diagnostics/tests/imports/invisibleFakeReferenceInImport.fir.kt b/compiler/testData/diagnostics/tests/imports/invisibleFakeReferenceInImport.fir.kt
new file mode 100644
index 00000000000..1f21b6bb9aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/invisibleFakeReferenceInImport.fir.kt
@@ -0,0 +1,16 @@
+// FILE: A.kt
+
+import B.foo
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>
+}
+
+// FILE: B.kt
+object B : C<String>()
+
+// FILE: C.kt
+
+open class C<T> {
+    private var foo: String = "abc"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/kt13112.fir.kt b/compiler/testData/diagnostics/tests/imports/kt13112.fir.kt
new file mode 100644
index 00000000000..2443edbe356
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/kt13112.fir.kt
@@ -0,0 +1,46 @@
+// FILE: 1.kt
+
+package anotherpackage
+
+interface IInterfaceInput<in T> {
+    fun doSomething(input: T)
+}
+
+// FILE: 2.kt
+
+package anotherpackage
+
+interface IInterfaceOutput<out T> {
+    fun doSomething(): T?
+}
+
+// FILE: 3.kt
+
+package mypackage.nestedpackage
+
+import mypackage.nestedpackage.Bar.Baz
+import anotherpackage.IInterfaceInput
+import anotherpackage.IInterfaceOutput
+
+class Foo() {
+    class FooNest {
+        val bar = Bar()
+
+        fun myFun(): List<Baz> {
+            return <!UNRESOLVED_REFERENCE!>listOf<!>(bar.doSomething())
+        }
+    }
+}
+
+class Bar() : IInterfaceInput<Baz>, IInterfaceOutput<Baz> {
+    override fun doSomething(input: Baz) {
+        throw UnsupportedOperationException("not implemented")
+    }
+
+    override fun doSomething(): Baz {
+        throw UnsupportedOperationException("not implemented")
+    }
+
+}
+
+data class Baz(val myField: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/propertyClassFileDependencyRecursion.fir.kt b/compiler/testData/diagnostics/tests/imports/propertyClassFileDependencyRecursion.fir.kt
new file mode 100644
index 00000000000..92a05929628
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/propertyClassFileDependencyRecursion.fir.kt
@@ -0,0 +1,17 @@
+// FILE: propertyClassFileDependencyRecursion.kt
+package test
+
+import other.prop
+
+// Note: "prop" is expected to be unresolved and replaced to Any
+class PropType: prop
+
+// Note: this time "prop" should be resolved and type should be inferred for "checkTypeProp"
+val checkTypeProp = prop
+
+// FILE: propertyClassFileDependencyRecursionOther.kt
+package other
+
+import test.PropType
+
+val prop: PropType? = null
diff --git a/compiler/testData/diagnostics/tests/imports/twoImportLists.fir.kt b/compiler/testData/diagnostics/tests/imports/twoImportLists.fir.kt
new file mode 100644
index 00000000000..ac3a130affe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/imports/twoImportLists.fir.kt
@@ -0,0 +1,105 @@
+// !WITH_NEW_INFERENCE
+// FILE:a.kt
+package a
+
+<!SYNTAX!><<!><!SYNTAX!><<!><!SYNTAX!><<!> <!SYNTAX!>FOOO<!><!SYNTAX!><!>
+import b.B        //class
+import b.foo      //function
+import b.ext      //extension function
+import b.value    //property
+import b.C.Companion.bar    //function from companion object
+import b.C.Companion.cValue //property from companion object
+import b.constant.fff     //function from val
+import b.constant.dValue  //property from val
+import smth.illegal
+import b.C.smth.illegal
+
+<!SYNTAX!><<!><!SYNTAX!><<!><!SYNTAX!><<!><!SYNTAX!>HEAD<!><!SYNTAX!><!>
+import b.bar.smth
+import b.bar.*
+import b.unr.unr.unr
+import unr.unr.unr
+import b.constant
+import b.E.Companion.f      //val from companion object
+
+fun test(arg: B) {
+    foo(value)
+    arg.ext()
+
+    bar()
+    foo(cValue)
+
+    <!UNRESOLVED_REFERENCE!>fff<!>(<!UNRESOLVED_REFERENCE!>dValue<!>)
+
+    constant.fff(constant.dValue)
+
+    f.f()
+}
+
+// FILE:b.kt
+package b
+
+class B() {}
+
+fun foo(i: Int) = i
+
+fun B.ext() {}
+
+val value = 0
+
+class C() {
+    companion object {
+        fun bar() {}
+        val cValue = 1
+    }
+}
+
+class D() {
+    fun fff(s: String) = s
+    val dValue = "w"
+}
+
+val constant = D()
+
+class E() {
+    companion object {
+        val f = F()
+    }
+}
+
+class F() {
+    fun f() {}
+}
+
+fun bar() {}
+
+//FILE:c.kt
+package c
+
+import c.C.*
+
+object C {
+    fun f() {
+    }
+    val i = 348
+}
+
+fun foo() {
+    if (i == 3) f()
+}
+
+//FILE:d.kt
+package d
+
+import d.A.Companion.B
+import d.A.Companion.C
+
+val b : B = B()
+val c : B = C
+
+class A() {
+    companion object {
+        open class B() {}
+        object C : B() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/NoSenselessComparisonForErrorType.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/NoSenselessComparisonForErrorType.fir.kt
new file mode 100644
index 00000000000..cb1263a3d90
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/NoSenselessComparisonForErrorType.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+package a
+
+fun foo() {
+    val a = <!UNRESOLVED_REFERENCE!>getErrorType<!>()
+    if (a == null) { //no senseless comparison
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/SupertypeOfErrorType.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/SupertypeOfErrorType.fir.kt
new file mode 100644
index 00000000000..f821e212a64
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/SupertypeOfErrorType.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+package a
+
+import java.util.Date
+import java.util.Comparator
+
+fun foo() {
+
+    val c: Comparator<Date?> = comparator { date1, date2 ->
+        if (date1 != null && date2 != null) {
+            date1.compareTo(date2) * -11
+        } else {
+            11
+        }
+    }
+}
+
+fun bar(i: Int, a: U) {
+    val r = if (true) i else a
+    val b: Any = r
+}
+
+//from standard library
+public inline fun <T> comparator(fn: (T,T) -> Int): Comparator<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/arrayBracketsRange.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/arrayBracketsRange.fir.kt
new file mode 100644
index 00000000000..28f07365aa7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/arrayBracketsRange.fir.kt
@@ -0,0 +1,9 @@
+package b
+
+fun main() {
+    var ints : Array<Int?> = arrayOfNulls<Int>(31)
+
+    ints[0] = 4; ints[11] = 5; ints[2] =7
+    for(i in 0..ints.size)
+        ints[i<!SYNTAX!><!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/checkNothingIsSubtype.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/checkNothingIsSubtype.fir.kt
new file mode 100644
index 00000000000..6a13250ac61
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/checkNothingIsSubtype.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+package d
+
+interface A<T>
+
+fun <T> infer(a: A<T>) : T {}
+
+fun test(nothing: Nothing?) {
+    val i = infer(nothing)
+}
+
+fun sum(a : IntArray) : Int {
+<!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (n
+<!SYNTAX!>return<!><!SYNTAX!><!> "?"<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/controlStructuresErrors.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/controlStructuresErrors.fir.kt
new file mode 100644
index 00000000000..5b570ea91e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/controlStructuresErrors.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+
+fun test1() {
+    if (<!UNRESOLVED_REFERENCE!>rr<!>) {
+        if (<!UNRESOLVED_REFERENCE!>l<!>) {
+            <!UNRESOLVED_REFERENCE!>a<!>.<!UNRESOLVED_REFERENCE!>q<!>()
+        }
+        else {
+            <!UNRESOLVED_REFERENCE!>a<!>.<!UNRESOLVED_REFERENCE!>w<!>()
+        }
+    }
+    else {
+        if (<!UNRESOLVED_REFERENCE!>n<!>) {
+            <!UNRESOLVED_REFERENCE!>a<!>.<!UNRESOLVED_REFERENCE!>t<!>()
+        }
+        else {
+            <!UNRESOLVED_REFERENCE!>a<!>.<!UNRESOLVED_REFERENCE!>u<!>()
+        }
+    }
+}
+
+fun test2(l: List<AA>) {
+    l.<!UNRESOLVED_REFERENCE!>map<!> {
+        <!UNRESOLVED_REFERENCE!>it<!>!!
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/arrayExpression.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/arrayExpression.fir.kt
new file mode 100644
index 00000000000..d25e0ca5648
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/arrayExpression.fir.kt
@@ -0,0 +1,8 @@
+// !WITH_NEW_INFERENCE
+package bar
+
+fun main() {
+    class Some
+
+    Some[<!SYNTAX!><!>] <!UNRESOLVED_REFERENCE!>names<!> <!UNRESOLVED_REFERENCE!><!SYNTAX!>=<!> ["ads"]<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/checkBackingFieldException.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/checkBackingFieldException.fir.kt
new file mode 100644
index 00000000000..439724d5a0a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/checkBackingFieldException.fir.kt
@@ -0,0 +1,17 @@
+package h
+
+class Square() {
+  var size : Double =
+  <!UNRESOLVED_REFERENCE!>set<!>(<!UNRESOLVED_REFERENCE!>value<!>) {
+    <!SYNTAX!>$area<!> <!SYNTAX!>= size * size<!>
+  }
+
+  var area : Double
+  private set
+}
+
+fun main() {
+  val s = Square()
+
+  s.size = 2.0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/completeFunctionArgumentsOfNestedCalls.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/completeFunctionArgumentsOfNestedCalls.fir.kt
new file mode 100644
index 00000000000..96dadd79db6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/completeFunctionArgumentsOfNestedCalls.fir.kt
@@ -0,0 +1,8 @@
+package c
+
+fun demo() {
+    val bar = 51
+    fun map(f : <!SYNTAX!><!SYNTAX!><!>fun<!>
+    val foo = 3;
+    bar <!INAPPLICABLE_CANDIDATE!>+<!> map { foo }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/declarationAfterDotSelectorExpected.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/declarationAfterDotSelectorExpected.fir.kt
new file mode 100644
index 00000000000..c983234e53f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/declarationAfterDotSelectorExpected.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun foo(x: Any) {
+    x.<!SYNTAX!><!>
+    val foo = 1
+
+    x.<!SYNTAX!><!>
+    fun bar() = 2
+
+    x.
+    fun String.() = 3
+
+    var a = 24.<!SYNTAX!><!>
+    var b = 42.0
+}
+
+class A {
+    val z = "a".<!SYNTAX!><!>
+    val x = 4
+
+    val y = "b".<!SYNTAX!><!>
+    fun baz() = 5
+
+    val q = "c".
+    fun String.() = 6
+
+    var a = 24.<!SYNTAX!><!>
+    var b = 42.0
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/declarationAfterIncompleteElvis.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/declarationAfterIncompleteElvis.fir.kt
new file mode 100644
index 00000000000..1ddc5f31308
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/declarationAfterIncompleteElvis.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+fun foo(x: Any?) {
+    x ?:<!SYNTAX!><!>
+    val foo = 1
+
+    x ?:<!SYNTAX!><!>
+    fun bar() = 2
+
+    val res: String.() -> Int = null ?:
+    fun String.() = 3
+}
+
+class A {
+    val z = null ?:<!SYNTAX!><!>
+    val x = 4
+
+    val y = null ?:<!SYNTAX!><!>
+    fun baz() = 5
+
+    val q = null ?:
+    fun String.() = 6
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funEquals.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funEquals.fir.kt
new file mode 100644
index 00000000000..b397ef72dc6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funEquals.fir.kt
@@ -0,0 +1 @@
+fun foo() =<!SYNTAX!><!>
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funKeyword.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funKeyword.fir.kt
new file mode 100644
index 00000000000..f773d983a7d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funKeyword.fir.kt
@@ -0,0 +1 @@
+fun<!SYNTAX, SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funcitonTypes.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funcitonTypes.fir.kt
new file mode 100644
index 00000000000..36c7d2ced15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/funcitonTypes.fir.kt
@@ -0,0 +1 @@
+class A : (categoryName: <!SYNTAX!><!>)<!SYNTAX!><!> <!SYNTAX!><!>{<!SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteEnumReference.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteEnumReference.fir.kt
new file mode 100644
index 00000000000..ef56e1ca39a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteEnumReference.fir.kt
@@ -0,0 +1,11 @@
+enum class E {
+    A,
+    B,
+    C
+}
+
+fun foo() {
+    val e = E.<!SYNTAX!><!>
+}
+
+
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteVal.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteVal.fir.kt
new file mode 100644
index 00000000000..f64b8ae0cff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteVal.fir.kt
@@ -0,0 +1,3 @@
+package c
+
+val i =<!SYNTAX!><!>
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteValWithAccessor.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteValWithAccessor.fir.kt
new file mode 100644
index 00000000000..400320515ef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteValWithAccessor.fir.kt
@@ -0,0 +1,3 @@
+package c
+
+val i : String get() =<!SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteWhen.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteWhen.fir.kt
new file mode 100644
index 00000000000..e169c711d74
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/incompleteWhen.fir.kt
@@ -0,0 +1,3 @@
+fun test(a: Any) {
+    when (a)<!SYNTAX!><!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/namedFun.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/namedFun.fir.kt
new file mode 100644
index 00000000000..b0c6be61c67
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/namedFun.fir.kt
@@ -0,0 +1 @@
+fun bar()
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/noTypeParamsInReturnType.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/noTypeParamsInReturnType.fir.kt
new file mode 100644
index 00000000000..859e1d1b28f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/noTypeParamsInReturnType.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+package b
+
+fun <T, R> foo(map: Map<T, R>) : R = throw Exception()
+
+fun <F, G> getMap() : Map<F, G> = throw Exception()
+
+fun bar123() {
+    foo(<!INAPPLICABLE_CANDIDATE!>getMap<!>(
+<!SYNTAX!><!>}
+
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/typeReferenceError.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/typeReferenceError.fir.kt
new file mode 100644
index 00000000000..d611ecb41b0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/typeReferenceError.fir.kt
@@ -0,0 +1,3 @@
+package typeReferenceError
+
+class Pair<<!SYNTAX!><!>:<!UNRESOLVED_REFERENCE!>(val c: <!SYNTAX!><!SYNTAX!><!>fun<!><!SYNTAX!><!> main<!>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valNoName.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valNoName.fir.kt
new file mode 100644
index 00000000000..054ff973a76
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valNoName.fir.kt
@@ -0,0 +1,43 @@
+// VAL
+class A(
+        val<!SYNTAX!><!>
+        val x: Int,
+        val
+        private<!SYNTAX!><!> val z: Int,
+        val<!SYNTAX!><!>
+)
+
+val<!SYNTAX!><!>
+fun foo() {}
+
+class B {
+    val<!SYNTAX!><!>
+    fun foo() {}
+
+    fun bar() {
+        val<!SYNTAX!><!>
+        fun foo() {}
+    }
+}
+
+// VAR
+class C(
+        var<!SYNTAX!><!>
+        val x: Int,
+        var
+        private<!SYNTAX!><!> val z: Int,
+        var<!SYNTAX!><!>
+)
+
+var<!SYNTAX!><!>
+fun baz() {}
+
+class D {
+    var<!SYNTAX!><!>
+    fun foo() {}
+
+    fun bar() {
+        var<!SYNTAX!><!>
+        fun foo() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valWithNoNameBeforeNextDeclarationWithModifiers.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valWithNoNameBeforeNextDeclarationWithModifiers.fir.kt
new file mode 100644
index 00000000000..0b315e01230
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valWithNoNameBeforeNextDeclarationWithModifiers.fir.kt
@@ -0,0 +1,15 @@
+abstract class A {
+    private val<!SYNTAX!><!>
+    // private is parsed as val's identifier
+    private fun foo1() {
+    }
+
+    private val<!SYNTAX!><!>
+    protected abstract fun foo2()
+
+    private val<!SYNTAX!><!>
+    fun foo3() {
+    }
+
+    private val private<!SYNTAX!><!> fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valWithNoNameInBlock.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valWithNoNameInBlock.fir.kt
new file mode 100644
index 00000000000..f444cae9c97
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/diagnosticWithSyntaxError/valWithNoNameInBlock.fir.kt
@@ -0,0 +1,50 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun println(x: String) {
+}
+
+fun run(block: () -> Unit) {}
+
+val propertyNameOnTheNextLine = 1
+
+fun foo() {
+    val<!SYNTAX!><!>
+    println("abc")
+
+    val<!SYNTAX!><!>
+    run {
+        println("abc")
+    }
+
+    val<!SYNTAX!><!>
+    if (1 == 1) {
+
+    }
+
+    val<!SYNTAX!><!>
+    (1 + 2)
+
+    // `propertyNameOnTheNextLine` parsed as simple name expression
+    val<!SYNTAX!><!>
+    propertyNameOnTheNextLine
+
+    val<!SYNTAX!><!>
+    // comment
+    propertyNameOnTheNextLine
+
+    val<!SYNTAX!><!> /* comment */
+    propertyNameOnTheNextLine
+
+    // Correct properties
+    val
+    property1 = 1
+
+    val
+    propertyWithBy by <!UNRESOLVED_REFERENCE!>lazy<!> { 1 }
+
+    val
+    propertyWithType: Int
+
+    val
+    (<!UNRESOLVED_REFERENCE!>a<!>, <!UNRESOLVED_REFERENCE!>b<!>) = 1
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/illegalSelectorCallableReference.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/illegalSelectorCallableReference.fir.kt
new file mode 100644
index 00000000000..3ed64132ea1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/illegalSelectorCallableReference.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+fun test() {
+    "a"."b"::foo
+    "a"."b"::class
+    "a"."b"."c"::foo
+    "a"."b"."c"::class
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/inExpr.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/inExpr.fir.kt
new file mode 100644
index 00000000000..e53e01564df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/inExpr.fir.kt
@@ -0,0 +1,5 @@
+package l
+
+fun test(a: Int) {
+    if (a <!UNRESOLVED_REFERENCE!>in<!><!SYNTAX!><!> ) {} //a is not unresolved
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/incompleteAssignment.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/incompleteAssignment.fir.kt
new file mode 100644
index 00000000000..aa121282304
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/incompleteAssignment.fir.kt
@@ -0,0 +1,30 @@
+package sum
+
+import java.util.*
+fun sum(a : IntArray) : Int {
+    // Write your solution here
+    <!UNRESOLVED_REFERENCE!>res<!> = 0
+    for (e in a)
+        <!UNRESOLVED_REFERENCE, VARIABLE_EXPECTED!>res<!> +=<!SYNTAX!><!>
+}
+fun main() {
+    test(0)
+    test(1, 1)
+    test(-1, -1, 0)
+    test(6, 1, 2, 3)
+    test(6, 1, 1, 1, 1, 1, 1)
+}
+// HELPER FUNCTIONS
+fun test(expectedSum : Int, vararg data : Int) {
+    val actualSum = sum(data)
+    assertEquals(actualSum, expectedSum, "\ndata = ${Arrays.toString(data)}\n" +
+    "sum(data) = ${actualSum}, but must be $expectedSum ")
+}
+fun <T: Any> assertEquals(actual : T?, expected : T?, message : Any? = null) {
+    if (actual != expected) {
+        if (message == null)
+            throw AssertionError()
+        else
+            throw AssertionError(message)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/incompleteEquals.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/incompleteEquals.fir.kt
new file mode 100644
index 00000000000..bd83db1679b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/incompleteEquals.fir.kt
@@ -0,0 +1,3 @@
+package a
+
+fun foo(a: Any) = a ==<!SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/incompleteTryCatchBlock.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/incompleteTryCatchBlock.fir.kt
new file mode 100644
index 00000000000..9144e6fee12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/incompleteTryCatchBlock.fir.kt
@@ -0,0 +1,14 @@
+fun test1() {
+    try {
+
+    } catch (<!SYNTAX!><!>)<!SYNTAX!><!>
+}
+
+fun test2() {
+    try { }<!SYNTAX!><!>
+}
+
+fun test3() {
+    try {
+    } catch (<!SYNTAX!><!>{}<!SYNTAX!>)<!> {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/kt1955.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/kt1955.fir.kt
new file mode 100644
index 00000000000..b7aff9093fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/kt1955.fir.kt
@@ -0,0 +1,8 @@
+//KT-1955 Half a file is red on incomplete code
+
+package b
+
+fun foo() {
+    val a = 1<!SYNTAX!><!>
+
+
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/kt2014.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/kt2014.fir.kt
new file mode 100644
index 00000000000..0d63fefe59b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/kt2014.fir.kt
@@ -0,0 +1,20 @@
+//KT-2014 Better diagnostic when using property syntax to call a method
+package c
+
+class Foo {
+    fun prop() : Int = 1
+    fun bar(i: Int) : Int = i
+
+    val a : Int = 1
+}
+
+fun x(f : Foo) {
+    f.<!UNRESOLVED_REFERENCE!>prop<!>
+    f.<!UNRESOLVED_REFERENCE!>bar<!>
+
+    f.<!UNRESOLVED_REFERENCE!>a<!>()
+    <!UNRESOLVED_REFERENCE!>c<!>()
+    <!INAPPLICABLE_CANDIDATE!>R<!>()
+}
+
+object R {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/kt4866UnresolvedArrayAccess.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/kt4866UnresolvedArrayAccess.fir.kt
new file mode 100644
index 00000000000..63e21a0e0a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/kt4866UnresolvedArrayAccess.fir.kt
@@ -0,0 +1,5 @@
+//KT-4866 Resolve does not work inside brackets with unresolved reference before
+
+fun test(i: Int, j: Int) {
+    <!UNRESOLVED_REFERENCE!><!UNRESOLVED_REFERENCE!>foo<!>[i, j]<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/plusOnTheRight.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/plusOnTheRight.fir.kt
new file mode 100644
index 00000000000..7022fa3623b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/plusOnTheRight.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+//EA-35646
+package a
+
+class MyClass1 {
+    public operator fun unaryPlus() {}
+}
+
+fun main(arg: MyClass1) {
+    arg<!UNRESOLVED_REFERENCE!>+<!><!SYNTAX!><!>
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/pseudocodeTraverseNextInstructions.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/pseudocodeTraverseNextInstructions.fir.kt
new file mode 100644
index 00000000000..b79f12bebde
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/pseudocodeTraverseNextInstructions.fir.kt
@@ -0,0 +1,8 @@
+package b
+
+fun foo() {
+    <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (i in <!UNRESOLVED_REFERENCE!>collection<!>) {
+        {
+         break
+    }
+}<!SYNTAX!><!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/senselessComparisonWithNull.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/senselessComparisonWithNull.fir.kt
new file mode 100644
index 00000000000..21e0e292f51
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/senselessComparisonWithNull.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+package d
+
+fun foo(a : IntArray) {
+    if (null == <!UNRESOLVED_REFERENCE!>a<!>()<!SYNTAX!><!>
+<!SYNTAX!><!>}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/typeParameterOnLhsOfDot.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/typeParameterOnLhsOfDot.fir.kt
new file mode 100644
index 00000000000..f4e1f12e1ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/typeParameterOnLhsOfDot.fir.kt
@@ -0,0 +1,8 @@
+package bar
+
+class S<T> {
+    fun foo() {
+        <!OTHER_ERROR!>T<!>
+        <!OTHER_ERROR!>T<!>.<!UNRESOLVED_REFERENCE!>create<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/unresolvedArguments.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/unresolvedArguments.fir.kt
new file mode 100644
index 00000000000..0eb8580efed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/unresolvedArguments.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+//!DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> foo(i: Int, t: T) {}
+fun <T> foo(s: String, t: T) {}
+
+fun bar(i: Int) {}
+fun bar(s: String) {}
+
+fun test() {
+    <!AMBIGUITY!>foo<!>(<!UNRESOLVED_REFERENCE!>rrr<!>, 1)
+    <!AMBIGUITY!>bar<!>(<!UNRESOLVED_REFERENCE!>rrr<!>)
+}
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/unresolvedOperation.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/unresolvedOperation.fir.kt
new file mode 100644
index 00000000000..c314de08b1e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/unresolvedOperation.fir.kt
@@ -0,0 +1,4 @@
+fun foo(a: Int) {
+    <!UNRESOLVED_REFERENCE!>!<!><!UNRESOLVED_REFERENCE!>bbb<!>
+    <!UNRESOLVED_REFERENCE!>bbb<!> + a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/incompleteCode/variableDeclarationInSelector.fir.kt b/compiler/testData/diagnostics/tests/incompleteCode/variableDeclarationInSelector.fir.kt
new file mode 100644
index 00000000000..fdd9b6d8b09
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/incompleteCode/variableDeclarationInSelector.fir.kt
@@ -0,0 +1,4 @@
+fun foo(s: String) {
+    s.<!SYNTAX!><!>
+    val b = 42
+}
diff --git a/compiler/testData/diagnostics/tests/inference/NoInferenceFromDeclaredBounds.fir.kt b/compiler/testData/diagnostics/tests/inference/NoInferenceFromDeclaredBounds.fir.kt
new file mode 100644
index 00000000000..90f47681aa7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/NoInferenceFromDeclaredBounds.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+fun <T: Any> fooT22() : T? {
+  return null
+}
+
+fun foo1() {
+    fooT22()
+}
+
+val n : Nothing = null.sure()
+
+fun <T : Any> T?.sure() : T = this!!
diff --git a/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveAmbiguity.fir.kt
new file mode 100644
index 00000000000..c719e53bab0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveAmbiguity.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+package f
+
+fun <T> g(i: Int, a: Any): List<T> {throw Exception()}
+fun <T> g(a: Any, i: Int): Collection<T> {throw Exception()}
+
+fun <T> test() {
+    val c: List<T> = <!AMBIGUITY!>g<!>(1, 1)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveFunctionLiteralsNoUse.fir.kt b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveFunctionLiteralsNoUse.fir.kt
new file mode 100644
index 00000000000..8058e01af53
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveFunctionLiteralsNoUse.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+package f
+
+fun <R> h(i: Int, a: Any, r: R, f: (Boolean) -> Int) = 1
+fun <R> h(a: Any, i: Int, r: R, f: (Boolean) -> Int) = 1
+
+fun test() = <!AMBIGUITY!>h<!>(1, 1, 1, { b -> 42 })
diff --git a/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveNoInfoForParameter.fir.kt b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveNoInfoForParameter.fir.kt
new file mode 100644
index 00000000000..59123b0ae4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveNoInfoForParameter.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+package f
+
+fun <T> f(i: Int, c: Collection<T>): List<T> {throw Exception()}
+fun <T> f(a: Any, l: List<T>): Collection<T> {throw Exception()}
+
+fun <T> test(l: List<T>) {
+    <!AMBIGUITY!>f<!>(1, emptyList())
+}
+
+fun <T> emptyList(): List<T> {throw Exception()}
diff --git a/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveNoneApplicable.fir.kt b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveNoneApplicable.fir.kt
new file mode 100644
index 00000000000..ae5b852f858
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveNoneApplicable.fir.kt
@@ -0,0 +1,8 @@
+package f
+
+fun <T> f(i: Int, t: T, c: MutableCollection<T>) {}
+fun <T> f(a: Any, t: T, l: MutableList<T>) {}
+
+fun test(l: List<Int>) {
+    <!INAPPLICABLE_CANDIDATE!>f<!>(1, "", l)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveWithFunctionLiterals.fir.kt b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveWithFunctionLiterals.fir.kt
new file mode 100644
index 00000000000..f35f4fc87e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/cannotCompleteResolveWithFunctionLiterals.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -CONFLICTING_JVM_DECLARATIONS
+package f
+
+fun <R> h(f: (Boolean) -> R) = 1
+fun <R> h(f: (String) -> R) = 2
+
+fun test() = <!AMBIGUITY!>h<!>{ i -> getAnswer() }
+
+fun getAnswer() = 42
+
diff --git a/compiler/testData/diagnostics/tests/inference/capturedInProjectedFlexibleType.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedInProjectedFlexibleType.fir.kt
new file mode 100644
index 00000000000..6c51937918d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedInProjectedFlexibleType.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A<T> {
+    public A<? super T> getSuperA() { return null; }
+}
+
+// FILE: main.kt
+
+fun <T : Any> foo(x: T?, func: (T) -> T?) {}
+
+fun test(a: A<*>) {
+    foo(a) { it.superA }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/approximateBeforeFixation.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/approximateBeforeFixation.fir.kt
new file mode 100644
index 00000000000..d8f3fda3b6d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/approximateBeforeFixation.fir.kt
@@ -0,0 +1,8 @@
+
+fun <T> Array<out T>.intersect(other: Iterable<T>) {
+    val set = toMutableSet()
+    set.retainAll(other)
+}
+
+fun <X> Array<out X>.toMutableSet(): MutableSet<X> = TODO()
+fun <Y> MutableCollection<in Y>.retainAll(elements: Iterable<Y>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/cannotCaptureInProjection.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/cannotCaptureInProjection.fir.kt
new file mode 100644
index 00000000000..a62783a1480
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/cannotCaptureInProjection.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T: Any> bar(a: Array<T>): Array<T?> =  null!!
+
+fun test1(a: Array<in Int>) {
+    val r: Array<in Int?> = <!INAPPLICABLE_CANDIDATE!>bar<!>(a)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(a)
+}
+
+fun <T: Any> foo(l: Array<T>): Array<Array<T?>> = null!!
+
+fun test2(a: Array<in Int>) {
+    val r: Array<out Array<in Int?>> = <!INAPPLICABLE_CANDIDATE!>foo<!>(a)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/captureForNullableTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureForNullableTypes.fir.kt
new file mode 100644
index 00000000000..019da0ed399
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureForNullableTypes.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T: Any> bar(a: Array<T>): Array<T?> =  null!!
+
+fun test1(a: Array<out Int>) {
+    val r: Array<out Int?> = bar(a)
+    val t = bar(a)
+    t checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out Int?>>() }
+}
+
+fun <T: Any> foo(l: Array<T>): Array<Array<T?>> = null!!
+
+fun test2(a: Array<out Int>) {
+    val r: Array<out Array<out Int?>> = foo(a)
+    val t = foo(a)
+    t checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out Array<out Int?>>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/captureForPlatformTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureForPlatformTypes.fir.kt
new file mode 100644
index 00000000000..fe976e17094
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureForPlatformTypes.fir.kt
@@ -0,0 +1,27 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    public static <T> Class<T> foo(Class<T> clazz) {
+        return clazz;
+    }
+
+    public static <T> Class<Class<T>> bar(Class<T> clazz) {
+        throw new Exception();
+    }
+}
+
+// FILE: b.kt
+fun test1(clazz: Class<out Int>) {
+    val foo0: Class<out Int> = A.foo(clazz)
+    val foo1 = A.foo(clazz)
+    foo1 checkType { <!UNRESOLVED_REFERENCE!>_<!>< Class<out Int> >() }
+    foo1 checkType { <!UNRESOLVED_REFERENCE!>_<!>< Class<out Int?> >() }
+}
+
+fun tes2t(clazz: Class<in Int>) {
+    val foo0: Class<out Class<in Int>> = A.bar(clazz)
+    val foo1 = A.bar(clazz)
+    foo1 checkType { <!UNRESOLVED_REFERENCE!>_<!>< Class<out Class<in Int>> >() }
+    foo1 checkType { <!UNRESOLVED_REFERENCE!>_<!>< Class<out Class<in Int?>> >() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromNullableTypeVariable.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromNullableTypeVariable.fir.kt
new file mode 100644
index 00000000000..177d1f8c10f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromNullableTypeVariable.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+fun <T : Any> Array<T?>.filterNotNull(): List<T> = throw Exception()
+
+fun test1(a: Array<out Int?>) {
+    val list = a.<!INAPPLICABLE_CANDIDATE!>filterNotNull<!>()
+    list <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><List<Int>>() }
+}
+
+fun test2(vararg a: Int?) {
+    val list = a.<!INAPPLICABLE_CANDIDATE!>filterNotNull<!>()
+    list <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><List<Int>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromSubtyping.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromSubtyping.fir.kt
new file mode 100644
index 00000000000..6af1a91db5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromSubtyping.fir.kt
@@ -0,0 +1,9 @@
+fun <V, R, M : MutableMap<in R, out V>> mapKeysTo(destination: M): Inv3<R, V, M> {
+    val foo = associateByTo(destination)
+
+    return foo
+}
+
+fun < Y, Z, T : MutableMap<in Y, out Z>> associateByTo(destination: T): Inv3<Y, Z, T> = TODO()
+
+interface Inv3<A, B, C>
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromTypeParameterUpperBound.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromTypeParameterUpperBound.fir.kt
new file mode 100644
index 00000000000..b0672c7516a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureFromTypeParameterUpperBound.fir.kt
@@ -0,0 +1,11 @@
+interface Inv<T>
+
+fun <Y: X, X : Inv<out String>> foo(x: X, y: Y) {
+    val rX = <!INAPPLICABLE_CANDIDATE!>bar<!>(x)
+    rX.<!UNRESOLVED_REFERENCE!>length<!>
+
+    val rY = <!INAPPLICABLE_CANDIDATE!>bar<!>(y)
+    rY.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun <Y> bar(l: Inv<Y>): Y = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/captureTypeOnlyOnTopLevel.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureTypeOnlyOnTopLevel.fir.kt
new file mode 100644
index 00000000000..1d437d55c57
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/captureTypeOnlyOnTopLevel.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun <T> foo(array: Array<Array<T>>): Array<Array<T>> = array
+
+fun test(array: Array<Array<out Int>>) {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(array)
+
+    val f: Array<out Array<out Int>> = <!INAPPLICABLE_CANDIDATE!>foo<!>(array)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedType.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedType.fir.kt
new file mode 100644
index 00000000000..a032a30b87e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedType.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T> foo(array: Array<T>): Array<T> = array
+
+fun test1(a1: Array<out Int>) {
+    val b1: Array<out Int> = foo(a1)
+    val c1 = foo(a1)
+    c1 checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out Int>>() }
+}
+
+fun test2(a2: Array<in Int>) {
+    val b2: Array<in Int> = foo(a2)
+    val c2 = foo(a2)
+    c2 checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<in Int>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeAndApproximation.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeAndApproximation.fir.kt
new file mode 100644
index 00000000000..b0cc77cfab5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeAndApproximation.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T> foo(a: Array<T>): Array<Array<T>> = throw Exception()
+
+fun test1(a1: Array<out Int>) {
+    val b1: Array<out Array<out Int>> = foo(a1)
+    val c1 = foo(a1)
+    c1 checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out Array<out Int>>>() }
+}
+
+fun test2(a2: Array<in Int>) {
+    val b2: Array<out Array<in Int>> = foo(a2)
+    val c2 = foo(a2)
+    c2 checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out Array<in Int>>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeSubstitutedIntoOppositeProjection.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeSubstitutedIntoOppositeProjection.fir.kt
new file mode 100644
index 00000000000..8d039702800
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeSubstitutedIntoOppositeProjection.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T> foo1(a1: Array<in T>, a2: Array<T>): T = null!!
+
+fun test1(a1: Array<Int>, a2: Array<out Int>) {
+    foo1(a1, a2) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
+
+fun <T> foo2(a1: Array<T>, a2: Array<out T>): T = null!!
+
+fun test2(a1: Array<in Int>, a2: Array<Int>) {
+    foo2(a1, a2) checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeWithInnerTypealias.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeWithInnerTypealias.fir.kt
new file mode 100644
index 00000000000..f5a9613e048
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeWithInnerTypealias.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +NewInference
+
+import kotlin.reflect.KClass
+
+typealias MyString = String
+
+fun test(k: KClass<out MyString>) {
+    k::class.java
+}
+
+@Suppress("UPPER_BOUND_VIOLATED")
+public val <T> KClass<T>.java: Class<T> get() = TODO()
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeWithTypeVariableSubtyping.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeWithTypeVariableSubtyping.fir.kt
new file mode 100644
index 00000000000..bd4e8035bb6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/capturedTypeWithTypeVariableSubtyping.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun takeCovArray(a: Array<out Number>) {}
+fun takeInArray(a: Array<in Number>) {}
+
+fun <T> foo(): Array<out T> = TODO()
+fun <T> bar(): Array<in T> = TODO()
+
+fun <X> id(x: X): X = x
+fun <Z> arrayInId(z: Array<in Z>): Array<in Z> = z
+fun <Z> arrayOutId(z: Array<out Z>): Array<out Z> = z
+
+fun test() {
+    takeCovArray(foo())
+    takeInArray(bar())
+
+    takeCovArray(id(foo()))
+    takeInArray(id(bar()))
+
+    takeCovArray(arrayOutId(foo()))
+    takeInArray(arrayInId(bar()))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/expectedTypeMismatchWithInVariance.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/expectedTypeMismatchWithInVariance.fir.kt
new file mode 100644
index 00000000000..3408e5adfd2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/expectedTypeMismatchWithInVariance.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+fun <T> foo(a1: Array<T>, a2: Array<out T>): T = null!!
+
+fun test(a1: Array<in Int>, a2: Array<Int>) {
+
+    val c: Int = foo(a1, a2)
+
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/invokeCallWithCapturedReceiver.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/invokeCallWithCapturedReceiver.fir.kt
new file mode 100644
index 00000000000..7d205289439
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/invokeCallWithCapturedReceiver.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Inv1<T>
+
+operator fun <T> Inv1<T>.invoke(action: T.() -> Unit) {}
+
+fun test(inv: Inv1<out Number>) {
+    inv { }
+    inv.invoke { }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/kt25302.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/kt25302.fir.kt
new file mode 100644
index 00000000000..3096c1eefca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/kt25302.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface CollectorMock<A, R>
+
+interface StreamMock {
+    fun <R, A> collect(collector: CollectorMock<A, R>): R
+}
+
+fun <T> accept(s: T) {}
+fun ofK(t: String): StreamMock = TODO()
+fun <T> toSetK(): CollectorMock<*, T> = TODO()
+
+class KotlinCollectionUser1 {
+    fun use() {
+        accept(ofK("").collect(toSetK<String>()))
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/kt2570.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/kt2570.fir.kt
new file mode 100644
index 00000000000..505d3dbbefa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/kt2570.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun <T> foo(l: MutableList<T>): MutableList<T> = l
+fun test(l: MutableList<out Int>) {
+    val a: MutableList<out Int> = foo(l)
+    val b = foo(l)
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!>< MutableList<out Int> >() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/kt2872.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/kt2872.fir.kt
new file mode 100644
index 00000000000..6888e73ef5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/kt2872.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+fun <T> Array<T>.foo() {}
+
+fun test(array: Array<out Int>) {
+    array.foo()
+    array.<!INAPPLICABLE_CANDIDATE!>foo<!><out Int>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/memberScopeOfCaptured.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/memberScopeOfCaptured.fir.kt
new file mode 100644
index 00000000000..c09a56415ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/memberScopeOfCaptured.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+class A<T> {
+    fun foo(): T = null!!
+}
+
+fun <E> A<E>.bar(): A<in E> = this
+
+fun baz(x: A<out CharSequence>) {
+    x.bar() checkType { <!UNRESOLVED_REFERENCE!>_<!><A<*>>() }
+    x.bar().foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() } // See KT-10448
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/noCaptureTypeErrorForNonTopLevel.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/noCaptureTypeErrorForNonTopLevel.fir.kt
new file mode 100644
index 00000000000..29dc2d569ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/noCaptureTypeErrorForNonTopLevel.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A<T>
+class B<T>
+
+fun <E> foo(b: B<in A<E>>) {}
+fun <E> baz(b: B<out A<E>>) {}
+
+// See KT-13950
+fun bar(b: B<in A<out Number>>, bOut: B<out A<out Number>>, bOut2: B<out A<Number>>) {
+    foo(b)
+    foo<Number>(b)
+
+    <!INAPPLICABLE_CANDIDATE!>baz<!>(bOut)
+    <!INAPPLICABLE_CANDIDATE!>baz<!><Number>(bOut)
+
+    baz(bOut2)
+    baz<Number>(bOut2)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/notApproximateWhenCopyDescriptors.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/notApproximateWhenCopyDescriptors.fir.kt
new file mode 100644
index 00000000000..7b4046ca94a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/notApproximateWhenCopyDescriptors.fir.kt
@@ -0,0 +1,7 @@
+class Bar
+
+fun Bar.foo() = 42
+
+object MyObject {
+    fun foo(bar: Bar) = bar.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/overApproximationForInCaptured.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/overApproximationForInCaptured.fir.kt
new file mode 100644
index 00000000000..b14d2498fd2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/overApproximationForInCaptured.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T> foo(a: Array<T>): T = null!!
+
+fun test(a: Array<in Int>) {
+    foo(a) checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/overApproximationForOutCaptured.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/overApproximationForOutCaptured.fir.kt
new file mode 100644
index 00000000000..9c9fa4e59fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/overApproximationForOutCaptured.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T> foo(a: Array<T>): T = null!!
+
+fun test(a: Array<out Int>) {
+    foo(a) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/propagateNullailityOnSupertypesWhenCaptureTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/propagateNullailityOnSupertypesWhenCaptureTypes.fir.kt
new file mode 100644
index 00000000000..e4be6048e32
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/propagateNullailityOnSupertypesWhenCaptureTypes.fir.kt
@@ -0,0 +1,23 @@
+open class Inv<T>(val value: String)
+
+fun <T : Inv<*>?, F: Inv<out Any>?, G : Inv<*>> test1(t: T, f: F, g: G?) {
+    if (t != null && f != null && g != null) {
+        t.value
+        f.value
+        g.value
+    }
+}
+
+// Actually, this behavior is very questional as capturing shouldn't be performed deeper than for 1 level
+// But we preserve behavior of old inference here for now
+fun <T : K, K : Inv<*>?> test2(t: T) {
+    if (t != null) {
+        t.value
+    }
+}
+
+fun <T : Inv<K>?, K : Inv<*>?> test3(t: T) {
+    if (t != null) {
+        t.value
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.fir.kt
new file mode 100644
index 00000000000..bfee91bf948
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.fir.kt
@@ -0,0 +1,17 @@
+// See KT-14453
+val <T : Any> KClass1<T>.primaryConstructor: KFunction1<T>? get() = null!!
+
+interface KClass1<F : Any>
+interface KFunction1<out R>
+fun f(type: KClass1<*>): KFunction1<Any>? =
+        // What happens here:
+        // 1. Create captured type for type argument T (it's built upon star-projection from `KClass<*>` that's argument is <: Any)
+        // 2. Approximate resulting descriptor, now it 'KClass1<*>.primaryConstructor: KFunction1<*>'
+        //    Note that star-projection in 'KFunction1<*>' is obtained from KClass and its `projectionType` is Any (not-nullable).
+        //    Of course that situation is already strange
+        // 3. When checking subtyping after call completion we get that 'KFunction1<*>' is not a subtype of 'KFunction1<Any>' in new type checker.
+        //    The answer is correct, but this old type checker used `projectionType` for this and it was resulting in KFunction1<*> <: KFunction1<Any>
+        //
+        // So to fix the issue we use 'out starProjectionType' instead of star-projection itself in approximation
+        // Note that in new inference there should be no approximation for IN-position types (they must remain captured)
+        type.primaryConstructor
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/topLevelCapturingInsideReturnType.fir.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/topLevelCapturingInsideReturnType.fir.kt
new file mode 100644
index 00000000000..215df989c84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/topLevelCapturingInsideReturnType.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Inv2<T, K>
+
+fun <K> createInv(): Inv2<*, K> = TODO()
+
+fun <T> foo(i: Inv2<T, String>) {}
+
+fun foo() {
+    foo(createInv())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coerceFunctionLiteralToSuspend.fir.kt b/compiler/testData/diagnostics/tests/inference/coerceFunctionLiteralToSuspend.fir.kt
new file mode 100644
index 00000000000..6bd6ab8fb68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coerceFunctionLiteralToSuspend.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun fail1(c: suspend () -> Unit) {}
+
+fun fail2(c: () -> Unit) {}
+
+fun success1(c: suspend () -> Unit) {}
+
+fun test1() {
+    fail1(fun () {})
+    fun fail2(c: suspend () -> Unit) {}
+    fail2(fun () {})
+    fun success1(c: () -> Unit) {}
+    success1(fun() {})
+}
+
+suspend fun fail3(c: suspend () -> Unit) {}
+
+suspend fun fail4(c: () -> Unit) {}
+
+suspend fun success2(c: suspend () -> Unit) {}
+
+suspend fun test2() {
+    fail3(fun () {})
+    fun fail4(c: suspend () -> Unit) {}
+    fail4(fun () {})
+    fun success2(c: () -> Unit) {}
+    success2(fun() {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionToUnitForIfAsLastExpressionInLambda.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionToUnitForIfAsLastExpressionInLambda.fir.kt
new file mode 100644
index 00000000000..f911a70bde1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionToUnitForIfAsLastExpressionInLambda.fir.kt
@@ -0,0 +1,42 @@
+// !LANGUAGE: +NewInference
+
+class Obj
+
+fun foo(): String? {
+    run {
+        if (true) return@run
+
+        if (true) Obj()
+    }
+
+    run {
+        if (true) return@run
+
+        if (true) return Obj() // correct error, type check against return type of function "foo"
+    }
+
+    run {
+        if (true)
+            return@run
+        else
+            if (true) 42
+    }
+
+    run {
+        if (true)
+            42
+        else
+            if (true) 42
+    }
+
+    run {
+        if (true) return@run
+
+        if (true) {
+            Obj()
+        } else
+            if (true) return null
+    }
+
+    return ""
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionToUnitForLastLambdaInLambda.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionToUnitForLastLambdaInLambda.fir.kt
new file mode 100644
index 00000000000..07288febcce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionToUnitForLastLambdaInLambda.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun coerceToUnit(f: () -> Unit) {}
+
+class Inv<T>
+
+fun <K> builder(block: Inv<K>.() -> Unit): K = TODO()
+
+fun test() {
+    coerceToUnit {
+        builder {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExpectedType.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExpectedType.fir.kt
new file mode 100644
index 00000000000..a06dcfc4b07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExpectedType.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+
+fun <T> materialize(): T = TODO()
+
+val a: () -> Unit = l@{
+    // Expected type 'Unit' is used here for inference
+    if (true) return@l materialize()
+
+    // Expected type here is Unit, but it also implies coercion,
+    // so we can end lambda body with statement
+    if (true) 42
+}
+
+val b: () -> Unit = l@{
+    // Error, coercion can't be applied at this position!
+    if (true) return@l "hello"
+
+    // However, this is OK, because here coercion is applied
+    "hello"
+}
+
+val c: () -> Unit = {
+    // Interesting enough, for such expessions we use expected type Unit
+    // (compare that with the previous case, where we didn't used expected type Unit for "hello")
+    materialize()
+}
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExpectedTypeAndBound.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExpectedTypeAndBound.fir.kt
new file mode 100644
index 00000000000..fd1e8bfd4cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExpectedTypeAndBound.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+
+fun <T : Number> materializeNumber(): T = TODO()
+
+fun a(): Unit = run {
+    materializeNumber()
+}
+
+fun b(): Unit = run {
+    run {
+        materializeNumber()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExplicitTypeArgument.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExplicitTypeArgument.fir.kt
new file mode 100644
index 00000000000..d676c39e012
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExplicitTypeArgument.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_VARIABLE
+
+fun foo() {
+    val f = myRun<Unit> {
+        123
+    }
+}
+
+fun <R> myRun(block: () -> R): R = block()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithoutExpectedType.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithoutExpectedType.fir.kt
new file mode 100644
index 00000000000..ff5fd940d7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithoutExpectedType.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+
+fun <T> materialize(): T = TODO()
+
+fun implicitCoercion() {
+    val a = {
+        // Block is implicitly Unit-coerced, so it is allowed to place statement at the end of lambda
+        if (true) 42
+    }
+
+    val b = l@{
+        return@l
+    }
+
+    val c = l@{
+        // Error: block doesn't have an expected type, so call can't be inferred!
+        return@l materialize()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/indirectCoercionWithExpectedType.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/indirectCoercionWithExpectedType.fir.kt
new file mode 100644
index 00000000000..692bf78d0c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/indirectCoercionWithExpectedType.fir.kt
@@ -0,0 +1,36 @@
+// !WITH_NEW_INFERENCE
+
+fun <T> materialize(): T = TODO()
+
+fun a(): Unit = run {
+    run {
+        // Ok, block is coerced, because it has (indirectly) Unit-expected type
+        "hello"
+    }
+}
+
+fun b(): Unit = run {
+    // Ok, expected type is applied
+    materialize()
+}
+
+fun c(): Unit = run {
+    run {
+        // Attention!
+        // In OI expected type 'Unit' isn't applied here because of implementation quirks (note that OI still applies Unit in case 'e')
+        // In NI, it is applied and call is correctly inferred, which is consistent with the previous case
+        materialize()
+    }
+}
+
+fun d(): Unit = run outer@{
+    run inner@{
+        return@inner materialize()
+    }
+}
+
+fun e(): Unit = run outer@{
+    run inner@{
+        return@outer materialize()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/kt30242.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/kt30242.fir.kt
new file mode 100644
index 00000000000..0ad0a0b5f99
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/kt30242.fir.kt
@@ -0,0 +1,64 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// ISSUE: KT-30242
+
+class A
+
+fun println(s: String = "") {}
+
+fun foo(f: () -> Any) {}
+
+fun test1(b: Boolean) {
+    foo {
+        if (b) {
+            println("meh")
+        }
+    }
+}
+
+fun test2(b: Boolean) {
+    foo {
+        when {
+            b -> println("meh")
+        }
+    }
+}
+
+fun test3(b: Boolean) {
+    foo {
+        if (b) {
+            return@foo A()
+        }
+    }
+}
+
+fun test4(b: Boolean) {
+    foo {
+        if (b) {
+            return@foo println("meh")
+        }
+
+        if (b) {
+            println()
+        }
+    }
+}
+
+fun bar(block: () -> String) {}
+
+fun test_5(b: Boolean) {
+    bar {
+        if (b) {
+            println("meh")
+        }
+    }
+}
+
+fun test_6(b: Boolean) {
+    foo {
+        if (b) {
+            return@foo Unit
+        }
+        if (b) {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/noCoercion.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/noCoercion.fir.kt
new file mode 100644
index 00000000000..25ebd6d5781
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/noCoercion.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+fun noCoercionLastExpressionUsedAsReturnArgument() {
+    val a = {
+        42
+    }
+
+    a checkType { <!UNRESOLVED_REFERENCE!>_<!><() -> Int>() }
+}
+
+fun noCoercionBlockHasExplicitType() {
+    val b: () -> Int = {
+        if (true) 42
+    }
+}
+
+fun noCoercionBlockHasExplicitReturn() {
+    val c = l@{
+        if (true) return@l 42
+
+        if (true) 239
+    }
+}
+
+fun noCoercionInExpressionBody(): Unit = "hello"
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/coercionToUnit/nonPropagationOfCoercionToUnitInsideNestedLambda.fir.kt b/compiler/testData/diagnostics/tests/inference/coercionToUnit/nonPropagationOfCoercionToUnitInsideNestedLambda.fir.kt
new file mode 100644
index 00000000000..6adfb804c0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/coercionToUnit/nonPropagationOfCoercionToUnitInsideNestedLambda.fir.kt
@@ -0,0 +1,52 @@
+// !LANGUAGE: +NewInference
+
+class Obj
+
+fun foo(): String? {
+    run {
+        if (true) return@run
+
+        run {
+            if (true) {
+                Obj()
+            } else
+                if (true) return null // Error, coercion to Unit doesn't propagate inside nested lambdas
+        }
+
+        if (true) {
+            Obj()
+        } else
+            if (true) return null // OK, no error
+    }
+
+    run {
+        if (true) return@run
+
+        run {
+            if (true) {
+                Obj()
+            } else
+            if (true) return null // Error, coercion to Unit doesn't propagate inside nested lambdas
+        }
+    }
+
+    run {
+        if (true) return@run
+
+        run nestedRun@{
+            if (true) return@nestedRun
+
+            if (true) {
+                Obj()
+            } else
+                if (true) return null // OK, additional empty labeled return helps
+        }
+
+        if (true) {
+            Obj()
+        } else
+            if (true) return null // OK, no error
+    }
+
+    return ""
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/boundOnNullableVariable.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/boundOnNullableVariable.fir.kt
new file mode 100644
index 00000000000..72afc526eaf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/boundOnNullableVariable.fir.kt
@@ -0,0 +1,6 @@
+fun <T: Any> test(f: (T) -> T?) {
+    doFun(f.ext())
+}
+
+fun <E : Any> Function1<E, E?>.ext(): Function0<E?> = throw Exception()
+fun <R : Any> doFun(f: () -> R?) = f
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/cstFromNullableChildAndNonParameterizedType.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/cstFromNullableChildAndNonParameterizedType.fir.kt
new file mode 100644
index 00000000000..5f8200ffa51
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/cstFromNullableChildAndNonParameterizedType.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Base<out T>
+
+class ParameterizedChild<out R> : Base<R>
+class Child : Base<Nothing>
+
+fun <K> elvis(x: K?, y: K): K = TODO()
+fun <K> select(x: K, y: K): K = TODO()
+
+fun <V> myRun(f: () -> V): V = f()
+
+fun <S> test1(a: ParameterizedChild<S>?, b: Child): Base<S> = myRun {
+    elvis(a, b)
+}
+
+fun <S> test2(a: S?, b: S): S = myRun {
+    select(a, b)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/cstWithTypeContainingNonFixedVariable.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/cstWithTypeContainingNonFixedVariable.fir.kt
new file mode 100644
index 00000000000..6190d21fa8e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/cstWithTypeContainingNonFixedVariable.fir.kt
@@ -0,0 +1,88 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+fun <T> select(x: T, y: T): T = x
+open class Inv<K>
+class SubInv<V> : Inv<V>()
+
+fun testSimple() {
+    val a0 = select(Inv<Int>(), SubInv())
+
+    a0
+
+    val a1 = select(SubInv<Int>(), Inv())
+
+    a1
+}
+
+fun testNullability() {
+    val n1 = select(Inv<Int?>(), SubInv())
+
+    n1
+
+    val n2 = select(SubInv<Int?>(), Inv())
+
+    n2
+}
+
+fun testNested() {
+    val n1 = select(Inv<Inv<Int>>(), SubInv())
+
+    n1
+
+    val n2 = select(SubInv<SubInv<Int>>(), Inv())
+
+    n2
+
+    fun <K> createInvInv(): Inv<Inv<K>> = TODO()
+
+    val n3 = select(SubInv<SubInv<Int>>(), createInvInv())
+
+    n3
+}
+
+fun testCaptured(cSub: SubInv<out Number>, cInv: Inv<out Number>) {
+    val c1 = select(cInv, SubInv())
+
+    c1
+
+    val c2 = select(cSub, Inv())
+
+    c2
+}
+
+fun testVariableWithBound() {
+    fun <K : Number> createWithNumberBound(): Inv<K> = TODO()
+    fun <K : Int> createWithIntBound(): Inv<K> = TODO()
+
+    val c1 = select(SubInv<Int>(), createWithNumberBound())
+
+    c1
+
+    val c2 = select(SubInv<String>(), createWithNumberBound())
+
+    c2
+
+    val c3 = select(SubInv<Double>(), createWithIntBound())
+
+    c3
+}
+
+fun testCapturedVariable() {
+    fun <K> createInvOut(): Inv<out K> = TODO()
+    fun <V> createSubInvOut(): SubInv<out V> = TODO()
+
+    fun <K> createInvIn(): Inv<in K> = TODO()
+
+    val c1 = select(SubInv<Number>(), createInvOut())
+
+    c1
+
+    val c2 = select(createSubInvOut<Number>(), createInvOut())
+
+    c2
+
+    val c3 = select(SubInv<Number>(), createInvIn())
+
+    c3
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/dontCaptureTypeVariable.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/dontCaptureTypeVariable.fir.kt
new file mode 100644
index 00000000000..56b7f5657a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/dontCaptureTypeVariable.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import java.util.*
+
+fun test(list: ArrayList<Int>, comparatorFun: (Int, Int) -> Int) {
+    sort(list, Comparator(comparatorFun))
+}
+
+
+public fun <E> sort(list: List<E>, c: Comparator<in E>) {
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/fixVariablesInRightOrder.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/fixVariablesInRightOrder.fir.kt
new file mode 100644
index 00000000000..1e3724fee47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/fixVariablesInRightOrder.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class GenericClass<out T>
+
+public fun <K, V> GenericClass<Map<K, V>>.foo() {}
+
+public fun <T> bar(t: T, ext: GenericClass<T>.() -> Unit) {}
+
+fun test() {
+    bar(mapOf(2 to 3)) { foo() }
+}
+
+// from library
+class Pair<out A, out B>
+fun <K, V> mapOf(keyValuePair: Pair<K, V>): Map<K, V> = throw Exception()
+infix fun <A, B> A.to(that: B): Pair<A, B> = throw Exception()
+
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/genericCandidateInGenericClass.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/genericCandidateInGenericClass.fir.kt
new file mode 100644
index 00000000000..dc882ec4d8d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/genericCandidateInGenericClass.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class GenericClass<out T>(val value: T) {
+    public fun <P> foo(extension: T.() -> P) {}
+}
+
+public fun <E> GenericClass<List<E>>.bar() {
+    foo( { listIterator() })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/inferenceWithUpperBoundsInLambda.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/inferenceWithUpperBoundsInLambda.fir.kt
new file mode 100644
index 00000000000..7ab48bdff17
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/inferenceWithUpperBoundsInLambda.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import java.util.*
+
+interface Foo
+class Bar<B : Foo>(val list: MutableList<B>) {}
+
+fun <F : Foo> test(map: MutableMap<String, Bar<F>>) {
+
+    map.getOrPut1("", { Bar(ArrayList()) })
+}
+
+fun <K, V> MutableMap<K, V>.getOrPut1(key: K, defaultValue: () -> V): V = throw Exception()
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/kt30300.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/kt30300.fir.kt
new file mode 100644
index 00000000000..7d100e7d50e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/kt30300.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// Issue: KT-30300
+
+class Inv<T>
+class InvOut<T, out K>
+
+class Sample
+
+fun <T> select(x: T, y: T): T = x
+fun <K1, V1> selectInvOut(a: InvOut<out K1, V1>, b: InvOut<out K1, V1>): InvOut<K1, V1> = TODO()
+fun <K2, V2> emptyInvOut(): InvOut<K2, V2> = TODO()
+fun <S> create(element: S): InvOut<Inv<S>, S> = TODO()
+
+fun test(s: Sample, b: InvOut<Inv<*>, Any?>) {
+    selectInvOut(
+        b,
+        select(create(s), emptyInvOut())
+    )
+}
+
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/kt31969.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/kt31969.fir.kt
new file mode 100644
index 00000000000..6477411e023
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/kt31969.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+open class View
+
+fun test() {
+    val target = foo<View>() ?: foo() ?: run {}
+}
+
+fun <T : View> foo(): T? {
+    return null
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/kt32818.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/kt32818.fir.kt
new file mode 100644
index 00000000000..58e4ad63617
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/kt32818.fir.kt
@@ -0,0 +1,5 @@
+// !WITH_NEW_INFERENCE
+
+fun <T : Any> nullable(): T? = null
+
+val value = nullable<Int>() ?: nullable()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/kt33197.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/kt33197.fir.kt
new file mode 100644
index 00000000000..c36a9aa4909
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/kt33197.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+fun test(condition: Boolean) {
+    val list1 =
+        if (condition) mutableListOf<Int>()
+        else emptyList()
+
+    list1
+
+    val list2 =
+        if (condition) mutableListOf()
+        else emptyList<Int>()
+
+    list2
+}
+
+fun <T> mutableListOf(): MutableList<T> = TODO()
+fun <T> emptyList(): List<T> = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/kt3372toCollection.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/kt3372toCollection.fir.kt
new file mode 100644
index 00000000000..18cd4edb8d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/kt3372toCollection.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// KT-3372 Use upper bound in type argument inference
+
+import java.util.HashSet
+
+fun <T, C: MutableCollection<T>> Iterable<T>.toCollection(result: C) : C = throw Exception()
+
+fun test(list: List<Int>) {
+    val set = list.toCollection(HashSet())
+    set checkType { <!UNRESOLVED_REFERENCE!>_<!><HashSet<Int>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/lessSpecificTypeForArgumentCallWithExactAnnotation.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/lessSpecificTypeForArgumentCallWithExactAnnotation.fir.kt
new file mode 100644
index 00000000000..f34eb010880
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/lessSpecificTypeForArgumentCallWithExactAnnotation.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: -NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A
+interface B : A
+interface C : A
+
+@Suppress("INVISIBLE_REFERENCE")
+fun <K> select(x: K, y: K): @kotlin.internal.Exact K = x
+
+fun foo(a: Any) {}
+
+fun test(b: B, c: C) {
+    foo(
+        select(b, c)
+    )
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/lessSpecificTypeForArgumentCallWithExactAnnotation_ni.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/lessSpecificTypeForArgumentCallWithExactAnnotation_ni.fir.kt
new file mode 100644
index 00000000000..004d8442034
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/lessSpecificTypeForArgumentCallWithExactAnnotation_ni.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A
+interface B : A
+interface C : A
+
+@Suppress("INVISIBLE_REFERENCE")
+fun <K> select(x: K, y: K): @kotlin.internal.Exact K = x
+
+fun foo(a: Any) {}
+
+fun test(b: B, c: C) {
+    foo(
+        select(b, c)
+    )
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/manyArgumentsForVararg.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/manyArgumentsForVararg.fir.kt
new file mode 100644
index 00000000000..ad37f1b3559
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/manyArgumentsForVararg.fir.kt
@@ -0,0 +1,178 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+val prop = mapOf(
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b"),
+    to("a", "b")
+)
+
+fun <A, B> to(a: A, b: B): Pair<A, B> = TODO()
+fun <K, V> mapOf(vararg pairs: Pair<K, V>): Map<K, V> = TODO()
+
+class Pair<out A, out B>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/nestedLambdas.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/nestedLambdas.fir.kt
new file mode 100644
index 00000000000..3e81b84763c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/nestedLambdas.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T, R> Collection<T>.map(transform : (T) -> R) : List<R> = throw Exception()
+
+fun test(list: List<List<Int>>) {
+
+    val list1 = list.map { it.map { "$it" } }
+    list1 checkType { <!UNRESOLVED_REFERENCE!>_<!><List<List<String>>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/nonFixedVariableFromBothBranches.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/nonFixedVariableFromBothBranches.fir.kt
new file mode 100644
index 00000000000..03c5bcddc2e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/nonFixedVariableFromBothBranches.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+// FILE: JavaTest.java
+
+public class JavaTest {
+    public static Number[] createNumberArray() { return null; }
+}
+
+// FILE: test.kt
+
+fun <K> select(x: K, y: K): K = x
+
+fun <R> foo(f: () -> R): R = f()
+
+fun test(n: Number) {
+    val a = select(foo { JavaTest.createNumberArray() }, emptyArray())
+
+    a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/nonFixedVariableInsideFlexibleType.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/nonFixedVariableInsideFlexibleType.fir.kt
new file mode 100644
index 00000000000..a354fea3d48
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/nonFixedVariableInsideFlexibleType.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+// FILE: Inv2.java
+
+public class Inv2<K, V> {}
+
+// FILE: JavaSet.java
+
+public class JavaSet {
+    public static <E> java.util.Set<E> newIdentityHashSet() { return null; }
+
+    public static <K, V> V get(Inv2<K, V> slice, K key) { return null; }
+}
+
+// FILE: test.kt
+
+fun <K> select(x: K, y: K): K = x
+
+fun <K, T> addElementToSlice(
+    slice: Inv2<K, MutableCollection<T>>,
+    key: K,
+    element: T
+) {
+    val a = select(JavaSet.get(slice, key), JavaSet.newIdentityHashSet())
+
+    a
+
+    a.add(element)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/outProjectedTypeToOutProjected.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/outProjectedTypeToOutProjected.fir.kt
new file mode 100644
index 00000000000..fdc80f2c532
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/outProjectedTypeToOutProjected.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+class Inv<T>
+
+fun <K> select(x: K, y: K): K = x
+
+fun <V> outToOut(x: Inv<out V>): Inv<out V> = TODO()
+
+fun test(invOutAny: Inv<out Any>, invAny: Inv<Any>) {
+    val a: Inv<out Any> = select(invAny, outToOut(invOutAny))
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/postponedCompletionWithExactAnnotation.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/postponedCompletionWithExactAnnotation.fir.kt
new file mode 100644
index 00000000000..b5ee5094fca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/postponedCompletionWithExactAnnotation.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !LANGUAGE: -NewInference
+
+interface ISample
+
+fun <K> elvisSimple(x: K?, y: K): K = y
+
+@Suppress("INVISIBLE_REFERENCE")
+fun <K> elvisExact(x: K?, y: K): @kotlin.internal.Exact K = y
+
+fun <T : Number> materialize(): T? = TODO()
+
+fun test(nullableSample: ISample, any: Any) {
+    elvisSimple(
+        nullableSample,
+        materialize()
+    )
+
+    elvisSimple(
+        elvisSimple(nullableSample, materialize()),
+        any
+    )
+
+    elvisSimple(
+        elvisExact(nullableSample, materialize()),
+        any
+    )
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/postponedCompletionWithExactAnnotation_ni.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/postponedCompletionWithExactAnnotation_ni.fir.kt
new file mode 100644
index 00000000000..0b352bb01f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/postponedCompletionWithExactAnnotation_ni.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -UNCHECKED_CAST
+
+interface ISample
+
+fun <K> elvisSimple(x: K?, y: K): K = y
+
+@Suppress("INVISIBLE_REFERENCE")
+fun <K> elvisExact(x: K?, y: K): @kotlin.internal.Exact K = y
+
+fun <T : Number> materialize(): T? = null
+fun <T> Any?.materialize(): T = null as T
+
+fun test(nullableSample: ISample, any: Any) {
+    elvisSimple(
+        nullableSample,
+        materialize()
+    )
+
+    elvisSimple(
+        elvisSimple(nullableSample, materialize()),
+        any
+    )
+
+    elvisSimple(
+        elvisExact(nullableSample, materialize()),
+        any
+    )
+
+    val a: String? = null
+
+    val x1: String? = run {
+        a ?: a?.materialize()
+    }
+
+    val x2 = run {
+        a ?: a?.materialize()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/selectFromCovariantAndContravariantTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/selectFromCovariantAndContravariantTypes.fir.kt
new file mode 100644
index 00000000000..5dfa6d056e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/selectFromCovariantAndContravariantTypes.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class In<in T>
+class Out<out T>
+
+class A
+class B
+
+fun <K> select(x: K, y: K): K = x
+fun <V> genericIn(x: In<V>) {}
+fun <V> genericOut(x: Out<V>) {}
+
+fun test1(a: In<A>, b: In<B>) {
+    genericIn(select(a, b))
+}
+
+fun test2(a: Out<A>, b: Out<B>) {
+    genericOut(select(a, b))
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/selectFromTwoIncompatibleTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/selectFromTwoIncompatibleTypes.fir.kt
new file mode 100644
index 00000000000..11ce49a6588
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/selectFromTwoIncompatibleTypes.fir.kt
@@ -0,0 +1,24 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Inv<T>
+
+class A
+class B
+
+fun <K> select(x: K, y: K): K = x
+fun <V> generic(x: Inv<V>) {}
+
+fun test1(a: Inv<A>, b: Inv<B>) {
+    generic(select(a, b))
+}
+
+fun test2(a: Inv<*>?, b: Inv<*>) {
+    generic(a ?: b)
+    generic(if (a != null) a else b)
+    generic(a!!)
+}
+
+fun test3(a: Inv<out Any>, b: Inv<out Any>) {
+    generic(select(a, b))
+}
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/selectIntegerValueTypeFromIf.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/selectIntegerValueTypeFromIf.fir.kt
new file mode 100644
index 00000000000..c213e5b51a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/selectIntegerValueTypeFromIf.fir.kt
@@ -0,0 +1,8 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun takeLong(i: Long) {}
+
+fun test() {
+    takeLong(if (true) 1 else 0)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/commonSystem/theSameFunctionInArgs.fir.kt b/compiler/testData/diagnostics/tests/inference/commonSystem/theSameFunctionInArgs.fir.kt
new file mode 100644
index 00000000000..87ce95e3651
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/commonSystem/theSameFunctionInArgs.fir.kt
@@ -0,0 +1,6 @@
+// !CHECK_TYPE
+
+fun test() {
+    val array = arrayOf(arrayOf(1))
+    array checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<Array<Int>>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/completeInferenceIfManyFailed.fir.kt b/compiler/testData/diagnostics/tests/inference/completeInferenceIfManyFailed.fir.kt
new file mode 100644
index 00000000000..a63377b4fdb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/completeInferenceIfManyFailed.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+package d
+
+fun <T: Any> joinT(x: Int, vararg a: T): T? {
+    return null
+}
+
+fun <T: Any> joinT(x: Comparable<*>, y: T): T? {
+    return null
+}
+
+fun test() {
+    val x2 = <!INAPPLICABLE_CANDIDATE!>joinT<!>(Unit, "2")
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String?>(x2)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/conflictingSubstitutions.fir.kt b/compiler/testData/diagnostics/tests/inference/conflictingSubstitutions.fir.kt
new file mode 100644
index 00000000000..650d75a29c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/conflictingSubstitutions.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+package conflictingSubstitutions
+//+JDK
+
+import java.util.*
+
+fun <R> elemAndList(r: R, t: MutableList<R>): R = r
+fun <R> R.elemAndListWithReceiver(r: R, t: MutableList<R>): R = r
+
+fun test() {
+    val s = elemAndList(11, list("72"))
+
+    val u = 11.elemAndListWithReceiver(4, list("7"))
+}
+
+fun <T> list(value: T) : ArrayList<T> {
+    val list = ArrayList<T>()
+    list.add(value)
+    return list
+}
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/constraintFromVariantTypeWithNestedProjection.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/constraintFromVariantTypeWithNestedProjection.fir.kt
new file mode 100644
index 00000000000..17b3ea6aa8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/constraintFromVariantTypeWithNestedProjection.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Out<out T>
+class In<in T>
+class Inv<T>
+
+fun <R> choose1(c: Out<Out<R>>) {}
+fun <R> choose2(c: In<In<R>>) {}
+fun <R> choose3(c: Inv<Inv<R>>) {}
+
+fun f(o: Out<Out<*>>, i: In<In<*>>, inv: Inv<Inv<*>>) {
+    choose1(o)
+    choose2(i)
+    <!INAPPLICABLE_CANDIDATE!>choose3<!>(inv)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/constraintOnFunctionLiteral.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/constraintOnFunctionLiteral.fir.kt
new file mode 100644
index 00000000000..b77422491e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/constraintOnFunctionLiteral.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+package c
+
+import java.util.ArrayList
+
+fun Array<Int>.toIntArray(): IntArray = this.<!INAPPLICABLE_CANDIDATE!>mapTo<!>(IntArray(size), {<!UNRESOLVED_REFERENCE!>it<!>})
+
+fun Array<Int>.toArrayList(): ArrayList<Int> = this.mapTo(ArrayList<Int>(size), {it})
+
+public fun <T, R, C: MutableCollection<in R>> Array<out T>.mapTo(result: C, transform : (T) -> R) : C =
+        throw Exception("$result $transform")
+
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/definitelyNotNullTypeInvariantPosition.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/definitelyNotNullTypeInvariantPosition.fir.kt
new file mode 100644
index 00000000000..8b1bbe80eb4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/definitelyNotNullTypeInvariantPosition.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+class Inv<T>(val x: T?)
+
+fun <K> create(y: K) = Inv(y)
+fun <K> createPrivate(y: K) = Inv(y)
+
+fun takeInvInt(i: Inv<Int>) {}
+
+fun <S> test(i: Int, s: S) {
+    val a = Inv(s)
+
+    a
+
+    val b = create(i)
+
+    b
+
+    val c = createPrivate(i)
+
+    c
+
+    takeInvInt(create(i))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/earlyCompletionForCalls.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/earlyCompletionForCalls.fir.kt
new file mode 100644
index 00000000000..5213966e75c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/earlyCompletionForCalls.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Parent
+interface Inv<T>
+
+object Child : Parent
+
+fun <K : Parent> wrapper(): Inv<K> = TODO()
+fun <T : Parent> consume(wrapper: Inv<T>) {}
+
+fun <S> select(x: S, y: S): S = x
+
+fun error(f: Inv<out Parent>, w: Inv<Child>) {
+    consume(select(f, wrapper<Child>()))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.fir.kt
new file mode 100644
index 00000000000..c9e1f3c8eab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+interface A<T>
+
+fun <T> foo(a: A<T>, aN: A<T?>): T = throw Exception("$a $aN")
+
+fun <T> doA(a: A<T>): T = throw Exception("$a")
+
+fun test(a: A<Int>, aN: A<Int?>) {
+    val aa = doA(aN)
+    aa checkType {  <!UNRESOLVED_REFERENCE!>_<!><Int?>() }
+
+    val nullable = foo(aN, aN)
+    //T = Int?, T? = Int? => T = Int?
+    nullable checkType { <!UNRESOLVED_REFERENCE!>_<!><Int?>() }
+
+    val notNullable = foo(a, aN)
+    //T = Int, T? = Int? => T = Int
+    notNullable checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/errorUpperBoundConstraint.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/errorUpperBoundConstraint.fir.kt
new file mode 100644
index 00000000000..79934290420
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/errorUpperBoundConstraint.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: +NewInference
+
+// FILE: Sam.java
+
+public interface Sam<K> {
+    Sam.Result<K> compute();
+
+    public static class Result<V> {
+        public static <V> Sam.Result<V> create(V value) {}
+    }
+}
+
+// FILE: Foo.java
+
+public class Foo {
+    public static <T> void foo(Sam<T> var1) {
+    }
+}
+
+// FILE: test.kt
+
+fun test(e: ErrorType) {
+    Foo.foo {
+        Sam.Result.<!INAPPLICABLE_CANDIDATE!>create<!>(e)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/fixTypeVariableWithNothingConstraintEarlierThanComplexVariable.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/fixTypeVariableWithNothingConstraintEarlierThanComplexVariable.fir.kt
new file mode 100644
index 00000000000..210a2d9d3ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/fixTypeVariableWithNothingConstraintEarlierThanComplexVariable.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Inv<T>
+
+fun <K> foo(t: K?) = Inv<K>()
+
+fun <T> bar(t: T) = foo(t)
+fun <V1> bar1(t: V1): Inv<V1> = foo(t)
+fun <V2> bar2(t: V2): Inv<V2> = foo(t)
+
+fun <S> select(x: S, y: S): S = x
+
+fun <T> fail(t: T?) = if (t == null) bar(t) else bar(t)
+fun <F> fail1(t: F?, n: Nothing?) = select(bar1(n), bar2(t!!))
+fun <F> fail2(t: F?, n: Nothing?) = if (t == null) bar1(t) else bar2(t)
+fun <F> fail3(t: F?) = select(bar1(null), bar2(t?.let { it }))
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/ignoreConstraintFromImplicitInNothing.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/ignoreConstraintFromImplicitInNothing.fir.kt
new file mode 100644
index 00000000000..62b443f333a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/ignoreConstraintFromImplicitInNothing.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class Foo<T>
+
+fun <T> foo1(f: (T) -> Unit): Foo<T> = Foo()
+inline fun <reified T> foo2(f: (T) -> Unit): Foo<T> = Foo()
+
+fun test1() {
+    val f1: Foo<out Int> = foo1 { it checkType { _<Int>() } }
+    val f2: Foo<in Nothing> = foo1 { it checkType { _<Nothing>() } }
+
+    val f3: Foo<out Int> = foo2 { it checkType { _<Int>() } }
+    val f4: Foo<in Nothing> = foo2 { it checkType { _<Nothing>() } }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/inferTypeFromCapturedStarProjection.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/inferTypeFromCapturedStarProjection.fir.kt
new file mode 100644
index 00000000000..5daaf882c68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/inferTypeFromCapturedStarProjection.fir.kt
@@ -0,0 +1,5 @@
+interface Box<out R>
+fun <R> List<Box<R>>.choose(): Box<R>? = TODO()
+fun list(): List<Box<*>> = TODO()
+
+fun f() = list().choose()
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/kt6320.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/kt6320.fir.kt
new file mode 100644
index 00000000000..14a5aea2e24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/kt6320.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// AssertionError in ConstraintSystem(The constraint shouldn't contain different type variables on both sides: Y <: X)
+
+class A<X, Y : X>
+
+class B<X, Y : X>(foo: A<X, Y>) {
+    fun test1(a: A<X, Y>) {
+        B(a)
+        val b: B<X, Y> = B(a)
+        // crash here
+    }
+}
+
+class C<X, Z, Y : X>
+
+class D<X, Z, Y : X>(foo: C<X, Z, Y>) {
+    fun test(a: C<Y, Y, Y>) {
+        val d: D<X, Y, Y> = D(a)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/kt7351ConstraintFromUnitExpectedType.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/kt7351ConstraintFromUnitExpectedType.fir.kt
new file mode 100644
index 00000000000..d49d4c3a0bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/kt7351ConstraintFromUnitExpectedType.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+package kt7351
+
+interface Node
+
+interface Source<T> {
+    fun f() : T
+}
+fun <T, S : Source<T>> S.woo() : T = this.f()
+
+fun Node.append(block : Source<Int>.() -> Unit) {
+}
+
+fun crashMe(node : Node) {
+    node.append {
+        woo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/kt7433.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/kt7433.fir.kt
new file mode 100644
index 00000000000..1c9ad2d2e1d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/kt7433.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+public inline fun <S, T: S> Iterable<T>.reduce1(operation: (S, T) -> S): S = throw Exception()
+
+fun test(ints: List<Int>) {
+    val f: () -> Unit = {
+        ints.reduce1 { a, b -> a + b }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/kt8879.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/kt8879.fir.kt
new file mode 100644
index 00000000000..3aa989f59b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/kt8879.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Inv<I>
+interface Inv2<I>
+
+fun <T: Inv2<T>> foo(klass: Inv<T>): String? = null
+
+fun <X> bar(): Inv<X> = null!!
+
+fun test() {
+    foo(bar())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/manyConstraintsDueToFlexibleRawTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/manyConstraintsDueToFlexibleRawTypes.fir.kt
new file mode 100644
index 00000000000..85124e82e7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/manyConstraintsDueToFlexibleRawTypes.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+// SKIP_JAVAC
+
+// FILE: MySettings.java
+
+import java.util.Collection;
+
+public class MySettings<
+        SS extends MySettings<SS, PS, L>,
+        PS extends MyComparableSettings,
+        L extends MySettingsListener<PS>
+    >
+{
+    public Collection<PS> getLinkedProjectsSettings() {
+        return null;
+    }
+
+    public static MySettings getSettings() {
+        return null;
+    }
+}
+
+abstract class MyComparableSettings implements Comparable<MyComparableSettings> {}
+abstract class MySettingsListener<S extends MyComparableSettings> {}
+
+// FILE: test.kt
+
+fun test() {
+    val a = MySettings.getSettings()
+    a.getLinkedProjectsSettings()
+    a.linkedProjectsSettings
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/manyConstraintsDueToRecursiveFlexibleTypesWithWildcards.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/manyConstraintsDueToRecursiveFlexibleTypesWithWildcards.fir.kt
new file mode 100644
index 00000000000..499b2716ebd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/manyConstraintsDueToRecursiveFlexibleTypesWithWildcards.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+// SKIP_JAVAC
+
+// FILE: MySettings.java
+
+import java.util.Collection
+
+class MySettings<
+        SS extends MySettings<SS, PS, L>,
+        PS extends MyComparableSettings,
+        L extends MySettingsListener<PS>
+    >
+{
+    public Collection<PS> getLinkedProjectsSettings() {
+        return null;
+    }
+
+    public static MySettings<?, ?, ?> getSettings() {
+        return null;
+    }
+}
+
+abstract class MyComparableSettings implements Comparable<MyComparableSettings> {}
+abstract class MySettingsListener<S extends MyComparableSettings> {}
+
+// FILE: test.kt
+
+fun test() {
+    val a = MySettings.getSettings()
+    a.getLinkedProjectsSettings()
+    a.linkedProjectsSettings
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/notNullConstraintOnNullableType.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/notNullConstraintOnNullableType.fir.kt
new file mode 100644
index 00000000000..ac3cc49aa4f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/notNullConstraintOnNullableType.fir.kt
@@ -0,0 +1,25 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+interface A<T>
+
+interface In<in T>
+
+interface Out<out T>
+
+fun <T: Any> doT(t: T?): T = throw Exception("$t")
+fun <T: Any> doOut(o: Out<T?>): T { throw Exception("$o") }
+fun <T: Any> doIn(i: In<T?>) { throw Exception("$i") }
+fun <T: Any> doA(i: A<T?>) { throw Exception("$i") }
+
+fun test(out: Out<Int>, i: In<Int>, inv: A<Int>) {
+    // T? >: Int => T = Int
+    doT(1)
+    val r = doOut(out)
+    r checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    // T? <: Int => error
+    <!INAPPLICABLE_CANDIDATE!>doIn<!>(i)
+
+    // T? >: Int => error
+    <!INAPPLICABLE_CANDIDATE!>doA<!>(inv)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/operationsOnIntegerValueTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/operationsOnIntegerValueTypes.fir.kt
new file mode 100644
index 00000000000..de4197dadcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/operationsOnIntegerValueTypes.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test() {
+    generateException(Data(1), { Data(it.x + 2) })
+}
+
+fun <T> generateException(a: T, next: (T) -> T) {}
+
+class Data<out K>(val x: K)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/recursiveJavaTypeWithStarProjection.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/recursiveJavaTypeWithStarProjection.fir.kt
new file mode 100644
index 00000000000..730fdd640d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/recursiveJavaTypeWithStarProjection.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !LANGUAGE: +NewInference
+
+// FILE: MenuItemBase.java
+
+public class MenuItemBase<C extends ContextMenuBase<C, I, S>, I extends MenuItemBase<C, I, S>, S extends SubMenuBase<C, I, S>> {
+    public String getText() { return null; }
+}
+
+// FILE: ContextMenuBase.java
+
+public class ContextMenuBase<C extends ContextMenuBase<C, I, S>, I extends MenuItemBase<C, I, S>, S extends SubMenuBase<C, I, S>> {}
+
+// FILE: SubMenuBase.java
+
+public class SubMenuBase<C extends ContextMenuBase<C, I, S>, I extends MenuItemBase<C, I, S>, S extends SubMenuBase<C, I, S>> {}
+
+// FILE: test.kt
+
+fun test(m: MenuItemBase<*, *, *>) {
+    m.text
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/remainConstraintContainingTypeWithoutProjection.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/remainConstraintContainingTypeWithoutProjection.fir.kt
new file mode 100644
index 00000000000..c3add8bad9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/remainConstraintContainingTypeWithoutProjection.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -CAST_NEVER_SUCCEEDS
+// SKIP_TXT
+
+// FILE: Test.java
+import java.util.Collection;
+
+public class Test {
+    static <T> Inv<Collection<? extends T>> bar() {
+        return null;
+    }
+}
+
+// FILE: main.kt
+class Inv<E>
+
+fun <R> foo(x: R, y: Inv<R>) {}
+
+fun main() {
+    val values: List<Int> = null as List<Int>
+    /*
+     * Before the fix, there was type mismatch during checking `Test.bar()` to pass to `foo`:
+     *      Required: Inv<List<Int>>
+     *      Found: Inv<(MutableCollection<out Int!>..Collection<Int!>?)>
+     * Constraint `(MutableCollection<out T!>..Collection<T!>?)` from 'Found' (for TypeVariable(R)) has been removed
+     * during fixation TypeVariable(T) due to the constraint for R contained TypeVariable(T).
+     * The problem was that TypeVariable(T) wan't substituted due to `containsConstrainingTypeWithoutProjection` optimization.
+     */
+    foo(values, Test.bar())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/returnLambdaFromLambda.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/returnLambdaFromLambda.fir.kt
new file mode 100644
index 00000000000..0f100c7b735
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/returnLambdaFromLambda.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun testLambda() {
+    val basicTest: (Int) -> Int = myRun {
+        val x: Any? = null
+        if (x is String) return@myRun { it -> x.length <!AMBIGUITY!>+<!> it }
+        if (x !is Int) return@myRun { it -> it }
+
+        { it -> x + it }
+    }
+
+    val twoLambda: (Int) -> Int = myRun {
+        val x: Int = 1
+        run {
+            val y: Int = 2
+            { x + y }
+        }
+    }
+
+}
+
+inline fun <R> myRun(block: () -> R): R = block()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/subtypeConstraintOnNullableType.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/subtypeConstraintOnNullableType.fir.kt
new file mode 100644
index 00000000000..a4459ec1777
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/subtypeConstraintOnNullableType.fir.kt
@@ -0,0 +1,22 @@
+// !CHECK_TYPE
+interface A<T>
+
+interface Out<out T>
+
+fun <T> foo(a: A<T>, o: Out<T?>): T = throw Exception("$a $o")
+
+fun <T> doOut(o: Out<T?>): T = throw Exception("$o")
+
+fun test(a: A<Int>, aN: A<Int?>, o: Out<Int?>) {
+    val out = doOut(o)
+    //T? >: Int? => T >: Int
+    out checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    val nullable = foo(aN, o)
+    //T = Int?, T? >: Int? => T = Int?
+    nullable checkType { <!UNRESOLVED_REFERENCE!>_<!><Int?>() }
+
+    val notNullable = foo(a, o)
+    //T = Int, T? >: Int? => T = Int
+    notNullable checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/supertypeConstraintOnNullableType.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/supertypeConstraintOnNullableType.fir.kt
new file mode 100644
index 00000000000..8eecd698e16
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/supertypeConstraintOnNullableType.fir.kt
@@ -0,0 +1,22 @@
+// !CHECK_TYPE
+interface A<T>
+
+interface In<in T>
+
+fun <T> foo(a: A<T>, i: In<T>): T = throw Exception("$a $i")
+
+fun <T> doIn(i: In<T?>): T = throw Exception("$i")
+
+fun test(a: A<Int>, aN: A<Int?>, i: In<Int?>) {
+    val _in = doIn(i)
+    //T? <: Int? => T <: Int?
+    _in checkType { <!UNRESOLVED_REFERENCE!>_<!><Int?>() }
+
+    val notNullable = foo(a, i)
+    //T = Int, T? <: Int? => T = Int
+    notNullable checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    val nullable = foo(aN, i)
+    //T = Int?, T? <: Int? => T = Int?
+    nullable checkType { <!UNRESOLVED_REFERENCE!>_<!><Int?>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/wrongApproximationWithDefNotNullTypesAndDelegates.fir.kt b/compiler/testData/diagnostics/tests/inference/constraints/wrongApproximationWithDefNotNullTypesAndDelegates.fir.kt
new file mode 100644
index 00000000000..e64a8ec1c4c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/constraints/wrongApproximationWithDefNotNullTypesAndDelegates.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class Foo {
+    var test: String by refreshOnUpdate("str")
+
+    fun <T> refreshOnUpdate(initialValue: T) = RefreshDelegate(initialValue)
+
+    class RefreshDelegate<T>(initialValue: T?) {
+        operator fun getValue(thisRef: Foo, property: KProperty<*>): T = TODO()
+
+        operator fun setValue(thisRef: Foo, property: KProperty<*>, value: T) {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/dependOnExpectedType.fir.kt b/compiler/testData/diagnostics/tests/inference/dependOnExpectedType.fir.kt
new file mode 100644
index 00000000000..bae7a552814
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/dependOnExpectedType.fir.kt
@@ -0,0 +1,53 @@
+// !CHECK_TYPE
+
+package h
+//+JDK
+import java.util.*
+
+fun <T> id(t: T) : T = t
+
+fun <T> id1(t: T) = t
+
+fun <R> elem(t: List<R>): R = t.get(0)
+
+fun <R> elemAndList(r: R, t: List<R>): R = t.get(0)
+
+fun <T> both(t1: T, t2: T) : T = t1
+
+fun test1() {
+    val a = elem(list(2))
+    val b = id(elem(list(2)))
+    val c = id(id1(id(id1(list(33)))))
+    checkSubtype<Int>(a)
+    checkSubtype<Int>(b)
+    checkSubtype<List<Int>>(c)
+
+    val d : ArrayList<Int> = newList()
+    val e : ArrayList<Int> = id(newList())
+    val f : ArrayList<Int> = id(id1(id(id1(newList()))))
+
+    checkSubtype<List<Int>>(d)
+    checkSubtype<List<Int>>(e)
+    checkSubtype<List<Int>>(f)
+
+    val g = elemAndList("", newList())
+    val h = elemAndList<Long>(1, newList<Long>())
+
+    checkSubtype<String>(g)
+    checkSubtype<Long>(h)
+
+    val i = both(1, "")
+    val j = both(id(1), id(""))
+    checkSubtype<Any>(i)
+    checkSubtype<Any>(j)
+}
+
+fun <T> list(value: T) : ArrayList<T> {
+    val list = ArrayList<T>()
+    list.add(value)
+    return list
+}
+
+fun <S> newList() : ArrayList<S> {
+    return ArrayList<S>()
+}
diff --git a/compiler/testData/diagnostics/tests/inference/dependantOnVariance.fir.kt b/compiler/testData/diagnostics/tests/inference/dependantOnVariance.fir.kt
new file mode 100644
index 00000000000..14f7068d274
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/dependantOnVariance.fir.kt
@@ -0,0 +1,69 @@
+// !WITH_NEW_INFERENCE
+package a
+
+class MyList<T>(t: T) {}
+
+fun <T> getMyList(t: T)           : MyList<    T> = MyList(t)
+fun <T> getMyListToWriteTo(t: T)  : MyList< in T> = MyList(t)
+fun <T> getMyListToReadFrom(t: T) : MyList<out T> = MyList(t)
+
+fun <T> useMyList     (l: MyList<    T>, t: T) {}
+fun <T> writeToMyList (l: MyList< in T>, t: T) {}
+fun <T> readFromMyList(l: MyList<out T>, t: T) {}
+
+fun test1(int: Int, any: Any) {
+    val a0 : MyList<Any> = getMyList(int)
+
+    val a1 : MyList<Int> = getMyList(any)
+
+    val a2 : MyList<out Any> = getMyList(int)
+
+    val a3 : MyList<out Any> = getMyListToReadFrom(int)
+
+    val a4 : MyList<in Int> = getMyList(any)
+
+    val a5 : MyList<in Int> = getMyListToWriteTo(any)
+
+
+    val a6 : MyList<in Any> = getMyList<Int>(int)
+    val a7 : MyList<in Any> = getMyList(int)
+
+    val a8 : MyList<in Any> = getMyListToReadFrom<Int>(int)
+    val a9 : MyList<in Any> = getMyListToReadFrom(int)
+
+    val a10 : MyList<out Int> = getMyList<Any>(any)
+    val a11 : MyList<out Int> = getMyList(any)
+
+    val a12 : MyList<out Int> = getMyListToWriteTo<Any>(any)
+    val a13 : MyList<out Int> = getMyListToWriteTo(any)
+
+    useMyList(getMyList(int), int)
+    useMyList(getMyList(any), int)
+    useMyList(getMyList(int), any)
+
+    readFromMyList(getMyList(int), any)
+    readFromMyList(getMyList(any), int)
+    <!INAPPLICABLE_CANDIDATE!>readFromMyList<!><Int>(getMyList(any), int)
+
+    <!INAPPLICABLE_CANDIDATE!>readFromMyList<!><Int>(getMyListToReadFrom(any), int)
+    readFromMyList(getMyListToReadFrom(any), int)
+
+    readFromMyList(getMyListToReadFrom(int), any)
+
+
+    writeToMyList(getMyList(any), int)
+    writeToMyList<Any>(getMyList(int), any)
+    writeToMyList(getMyList<Any>(int), any)
+    writeToMyList(getMyList(int), any)
+
+    writeToMyList(getMyListToWriteTo(any), int)
+    writeToMyList(getMyListToWriteTo(int), any)
+
+    readFromMyList(getMyListToWriteTo(any), any)
+
+    <!INAPPLICABLE_CANDIDATE!>writeToMyList<!>(getMyListToReadFrom(any), any)
+
+    use(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13)
+}
+
+fun use(vararg a: Any) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/dependantOnVarianceNullable.fir.kt b/compiler/testData/diagnostics/tests/inference/dependantOnVarianceNullable.fir.kt
new file mode 100644
index 00000000000..f066b72e302
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/dependantOnVarianceNullable.fir.kt
@@ -0,0 +1,14 @@
+package b
+//+JDK
+
+import java.util.*
+import java.util.Collections.*
+
+fun foo(list: List<String>) : String {
+    val w : String = max(list, comparator<String?> {o1, o2 -> 1
+    })
+    return w
+}
+
+//from library
+fun <T> comparator(fn: (T,T) -> Int): Comparator<T> {}
diff --git a/compiler/testData/diagnostics/tests/inference/expectedTypeAdditionalTest.fir.kt b/compiler/testData/diagnostics/tests/inference/expectedTypeAdditionalTest.fir.kt
new file mode 100644
index 00000000000..1dac5d3aeb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/expectedTypeAdditionalTest.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ExpectedTypeFromCast
+
+fun foo() = 1
+
+fun <T> foo() = foo() as T
+
+fun <T> foo2(): T = TODO()
+
+val test = foo2().plus("") as String
+
+fun <T> T.bar() = this
+val barTest = "".bar() as Number
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/expectedTypeDoubleReceiver.fir.kt b/compiler/testData/diagnostics/tests/inference/expectedTypeDoubleReceiver.fir.kt
new file mode 100644
index 00000000000..a0ef0081b76
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/expectedTypeDoubleReceiver.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ExpectedTypeFromCast
+
+fun <T> foo(): T = TODO()
+
+class A {
+    fun <T> fooA(): T = TODO()
+}
+
+fun <V> id(value: V) = value
+
+val asA = foo().<!UNRESOLVED_REFERENCE!>fooA<!>() as A
+
+val receiverParenthesized = (foo()).<!UNRESOLVED_REFERENCE!>fooA<!>() as A
+val no2A = A().fooA().<!UNRESOLVED_REFERENCE!>fooA<!>() as A
+
+val correct1 = A().fooA() as A
+val correct2 = foo<A>().fooA() as A
+val correct3 = A().fooA<A>().fooA() as A
+
diff --git a/compiler/testData/diagnostics/tests/inference/expectedTypeFromCast.fir.kt b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCast.fir.kt
new file mode 100644
index 00000000000..ba4bafed1a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCast.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ExpectedTypeFromCast
+
+fun <T> foo(): T = TODO()
+
+fun <V> id(value: V) = value
+
+val asString = foo() as String
+
+val viaId = id(foo()) as String
+
+val insideId = id(foo() as String)
+
+val asList = foo() as List<String>
+
+val asStarList = foo() as List<*>
+
+val safeAs = foo() as? String
+
+val fromIs = foo() is String
+val fromNoIs = foo() !is String
diff --git a/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastComplexExpression.fir.kt b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastComplexExpression.fir.kt
new file mode 100644
index 00000000000..ce51ae98727
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastComplexExpression.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +ExpectedTypeFromCast
+
+package pp
+
+class A {
+    fun <T> foo(): T = TODO()
+
+    companion object {
+        fun <T> foo2(): T = TODO()
+    }
+}
+
+val x = A().foo() as String
+val y = A.foo2() as String
+val z = pp.A.foo2() as String
+
diff --git a/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastParenthesized.fir.kt b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastParenthesized.fir.kt
new file mode 100644
index 00000000000..0bdaa750a1c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/expectedTypeFromCastParenthesized.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: +ExpectedTypeFromCast
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class bar
+
+fun <T> foo(): T = TODO()
+
+fun <V> id(value: V) = value
+
+val par1 = (foo()) as String
+val par2 = ((foo())) as String
+
+val par3 = (dd@ (foo())) as String
+
+val par4 = ( @bar() (foo())) as String
+
+object X {
+    fun <T> foo(): T = TODO()
+}
+
+val par5 = ( @bar() X.foo()) as String
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/expectedTypeWithGenerics.fir.kt b/compiler/testData/diagnostics/tests/inference/expectedTypeWithGenerics.fir.kt
new file mode 100644
index 00000000000..c1054a13671
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/expectedTypeWithGenerics.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ExpectedTypeFromCast
+
+class X<S> {
+    fun <T : S> foo(): T = TODO()
+}
+
+fun test(x: X<Number>) {
+    val y = x.foo() as Int
+}
+
+fun <S, D: S> g() {
+    fun <T : S> foo(): T = TODO()
+
+    val y = foo() as Int
+
+    val y2 = foo() as D
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/findViewById.fir.kt b/compiler/testData/diagnostics/tests/inference/findViewById.fir.kt
new file mode 100644
index 00000000000..37c59b36098
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/findViewById.fir.kt
@@ -0,0 +1,59 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ExpectedTypeFromCast
+// !DIAGNOSTICS: -UNUSED_VARIABLE -DEBUG_INFO_LEAKING_THIS
+
+// FILE: a/View.java
+package a;
+
+public class View {
+
+}
+
+// FILE: a/Test.java
+package a;
+
+public class Test {
+    public <T extends View> T findViewById(int id);
+}
+
+// FILE: 1.kt
+package a
+
+
+class X : View()
+
+class Y<T> : View()
+
+val xExplicit: X = Test().findViewById(0)
+val xCast = Test().findViewById(0) as X
+
+val xCastExplicitType = Test().findViewById<X>(0) as X
+val xSafeCastExplicitType = Test().findViewById<X>(0) as? X
+
+val yExplicit: Y<String> = Test().findViewById(0)
+val yCast = Test().findViewById(0) as Y<String>
+
+
+class TestChild : Test() {
+    val xExplicit: X = findViewById(0)
+    val xCast = findViewById(0) as X
+
+    val yExplicit: Y<String> = findViewById(0)
+    val yCast = findViewById(0) as Y<String>
+}
+
+fun test(t: Test) {
+    val xExplicit: X = t.findViewById(0)
+    val xCast = t.findViewById(0) as X
+
+    val yExplicit: Y<String> = t.findViewById(0)
+    val yCast = t.findViewById(0) as Y<String>
+}
+
+fun test2(t: Test?) {
+    val xSafeCallSafeCast = t?.findViewById(0) as? X
+    val xSafeCallSafeCastExplicitType = t?.findViewById<X>(0) as? X
+
+    val xSafeCallCast = t?.findViewById(0) as X
+    val xSafeCallCastExplicitType = t?.findViewById<X>(0) as X
+}
diff --git a/compiler/testData/diagnostics/tests/inference/fixVariableToNothing.fir.kt b/compiler/testData/diagnostics/tests/inference/fixVariableToNothing.fir.kt
new file mode 100644
index 00000000000..3e1d827150f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/fixVariableToNothing.fir.kt
@@ -0,0 +1,15 @@
+
+// completion order here: X, Y, WHEN_VARIABLE
+fun <T> List<T>.optimizeReadOnlyList() = when (size) {
+    0 -> emptyList() // here type variable Y will be fixed to Nothing
+    1 -> listOf(this[0])
+    else -> this
+}
+fun <X> listOf(element: X): List<X> = TODO()
+fun <Y> emptyList(): List<Y> = TODO()
+
+
+fun test(l: List<String>): List<String> {
+    val foo = l.optimizeReadOnlyList()
+    return foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/fixationOrderForProperConstraints.fir.kt b/compiler/testData/diagnostics/tests/inference/fixationOrderForProperConstraints.fir.kt
new file mode 100644
index 00000000000..705e7193760
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/fixationOrderForProperConstraints.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+fun <X, Y, Z> foo(f: (Y) -> Z, g: (X) -> Y, x: X): Z = f(g(x))
+
+// TODO: Actually, this is a bug and will work when new inference is enabled
+// see ([NI] Select variable with proper non-trivial constraint first) for more details
+fun test() = foo({ it + 1 }, { it.length }, "")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/flexibleTypesAsUpperBound.fir.kt b/compiler/testData/diagnostics/tests/inference/flexibleTypesAsUpperBound.fir.kt
new file mode 100644
index 00000000000..dc0f951ef84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/flexibleTypesAsUpperBound.fir.kt
@@ -0,0 +1,13 @@
+// FILE: 1.kt
+fun <S> Array<S>.plus(): Array<S> {
+    val result = Arrays.copyOf(this, 3)
+    // result type is Array<(out) (S&Any)!>!
+    return result
+}
+
+// FILE: Arrays.java
+public class Arrays {
+    public static <T> T[] copyOf(T[] original, int newLength) {
+        return (T[]) null;
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/functionPlaceholderError.fir.kt b/compiler/testData/diagnostics/tests/inference/functionPlaceholderError.fir.kt
new file mode 100644
index 00000000000..790d98a513a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/functionPlaceholderError.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+package a
+
+fun <T> emptyList(): List<T> = throw Exception()
+
+fun <T> foo(f: T.() -> Unit, l: List<T>): T = throw Exception("$f$l")
+
+fun test() {
+    val q = foo(fun Int.() {}, emptyList()) //type inference no information for parameter error
+    checkSubtype<Int>(q)
+
+    foo({}, emptyList())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/genericAssignmentOperator.fir.kt b/compiler/testData/diagnostics/tests/inference/genericAssignmentOperator.fir.kt
new file mode 100644
index 00000000000..c35eb35f310
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/genericAssignmentOperator.fir.kt
@@ -0,0 +1,9 @@
+class R<T>
+
+fun <T> f(): R<T> = R<T>()
+
+operator fun Int.plusAssign(y: R<Int>) {}
+
+fun box() {
+    <!INAPPLICABLE_CANDIDATE!>1 += f()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/hasErrorInConstrainingTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/hasErrorInConstrainingTypes.fir.kt
new file mode 100644
index 00000000000..61e2939c97d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/hasErrorInConstrainingTypes.fir.kt
@@ -0,0 +1,8 @@
+package n
+
+fun <T> foo(t: T, t1: T) {}
+
+fun test() {
+    //no type inference error
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(<!UNRESOLVED_REFERENCE!>aaab<!>, <!UNRESOLVED_REFERENCE!>bbb<!>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/immutableArrayList.fir.kt b/compiler/testData/diagnostics/tests/inference/immutableArrayList.fir.kt
new file mode 100644
index 00000000000..6b8be3fbbdb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/immutableArrayList.fir.kt
@@ -0,0 +1,17 @@
+// FILE: p/J.java
+package p;
+
+public interface J {
+    public interface Super<T> {}
+    public interface Sub<T> extends Super<T> {}
+}
+
+// FILE: k.kt
+
+import p.J.*
+
+class Foo<T>: Sub<T> {
+    fun foo(): Super<T> {
+        return Foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/implicitInvokeExtensionWithFunctionalArgument.fir.kt b/compiler/testData/diagnostics/tests/inference/implicitInvokeExtensionWithFunctionalArgument.fir.kt
new file mode 100644
index 00000000000..9dad1baf906
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/implicitInvokeExtensionWithFunctionalArgument.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+class AbstractSelector<S, I>
+class SelectorFor<S>
+
+inline operator fun <S, I> SelectorFor<S>.invoke(f: S.() -> I): AbstractSelector<S, I> = TODO()
+
+class State(val p1: Double, val p2: () -> Int, val p3: String?)
+
+fun test(s: SelectorFor<State>): Double {
+    val a = s { p1 }
+    a checkType { <!UNRESOLVED_REFERENCE!>_<!><AbstractSelector<State, Double>>() }
+
+    val b = s { p2 }
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><AbstractSelector<State, () -> Int>>()}
+
+    val c = s { p3 }
+    c checkType { <!UNRESOLVED_REFERENCE!>_<!><AbstractSelector<State, String?>>() }
+
+    val d = s { }
+    d checkType { <!UNRESOLVED_REFERENCE!>_<!><AbstractSelector<State, Unit>>() }
+
+    val e = s { return p1 }
+    e checkType { <!UNRESOLVED_REFERENCE!>_<!><AbstractSelector<State, Nothing>>() }
+
+    return null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/implicitInvokeInCompanionObjectWithFunctionalArgument.fir.kt b/compiler/testData/diagnostics/tests/inference/implicitInvokeInCompanionObjectWithFunctionalArgument.fir.kt
new file mode 100644
index 00000000000..e1b9948e568
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/implicitInvokeInCompanionObjectWithFunctionalArgument.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+class TestClass {
+    companion object {
+        inline operator fun <T> invoke(task: () -> T) = task()
+    }
+}
+
+fun test(s: String): String {
+    val a = <!INAPPLICABLE_CANDIDATE!>TestClass<!> { "K" }
+    a <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    val b = <!INAPPLICABLE_CANDIDATE!>TestClass<!> { return s }
+    b <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Nothing>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/implicitInvokeInObjectWithFunctionalArgument.fir.kt b/compiler/testData/diagnostics/tests/inference/implicitInvokeInObjectWithFunctionalArgument.fir.kt
new file mode 100644
index 00000000000..88ee2013734
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/implicitInvokeInObjectWithFunctionalArgument.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+object TestClass {
+    inline operator fun <T> invoke(task: () -> T) = task()
+}
+
+fun test(s: String): String {
+    val a = <!INAPPLICABLE_CANDIDATE!>TestClass<!> { <!INAPPLICABLE_CANDIDATE!>TestClass<!> { TestClass } }
+    a <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><TestClass>() }
+
+    val b = <!INAPPLICABLE_CANDIDATE!>TestClass<!> { return s }
+    b <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Nothing>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/implicitInvokeWithFunctionLiteralArgument.fir.kt b/compiler/testData/diagnostics/tests/inference/implicitInvokeWithFunctionLiteralArgument.fir.kt
new file mode 100644
index 00000000000..cc6a8ce84ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/implicitInvokeWithFunctionLiteralArgument.fir.kt
@@ -0,0 +1,38 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+class TestClass {
+    inline operator fun <T> invoke(task: () -> T) = task()
+}
+
+fun <T> test(value: T, test: TestClass): T {
+    val x = test { return value }
+    x checkType { <!UNRESOLVED_REFERENCE!>_<!><Nothing>() }
+
+    return value
+}
+
+// ---
+
+class Future<T>
+
+interface FutureCallback<E> {
+    operator fun <T> invoke(f: (E) -> T): Future<T>
+}
+
+fun test(cb: FutureCallback<String>) {
+    val a = cb { it[0] }
+    a checkType { <!UNRESOLVED_REFERENCE!>_<!><Future<Char>>() }
+
+    val b = cb { it }
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><Future<String>>() }
+
+    val c = cb {}
+    c checkType { <!UNRESOLVED_REFERENCE!>_<!><Future<Unit>>() }
+
+    cb.let { callback ->
+        val d = callback { it.length }
+        d checkType { _<Future<Int>>() }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/inferInFunctionLiterals.fir.kt b/compiler/testData/diagnostics/tests/inference/inferInFunctionLiterals.fir.kt
new file mode 100644
index 00000000000..bee6cb003df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/inferInFunctionLiterals.fir.kt
@@ -0,0 +1,12 @@
+package n
+
+//+JDK
+import java.util.*
+
+fun <T> expected(t: T, f: () -> T) : T = t
+
+fun test(arrayList: ArrayList<Int>, list: List<Int>) {
+    val t = expected(arrayList, { list.reverse() })
+}
+
+fun <T> List<T>.reverse() : List<T> = this
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/inferInFunctionLiteralsWithReturn.fir.kt b/compiler/testData/diagnostics/tests/inference/inferInFunctionLiteralsWithReturn.fir.kt
new file mode 100644
index 00000000000..c4415224ee0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/inferInFunctionLiteralsWithReturn.fir.kt
@@ -0,0 +1,12 @@
+package n
+
+//+JDK
+import java.util.*
+
+fun <T> expected(t: T, f: () -> T) : T = t
+
+fun test(arrayList: ArrayList<Int>, list: List<Int>) {
+    val t = expected(arrayList, l@ {return@l list.reverse() })
+}
+
+fun <T> List<T>.reverse() : List<T> = this
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/intersectionTypeMultipleBoundsAsReceiver.fir.kt b/compiler/testData/diagnostics/tests/inference/intersectionTypeMultipleBoundsAsReceiver.fir.kt
new file mode 100644
index 00000000000..8c58629b05c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/intersectionTypeMultipleBoundsAsReceiver.fir.kt
@@ -0,0 +1,13 @@
+interface Foo<T>
+interface Bar<T>
+
+class Baz<T> : Foo<T>, Bar<T>
+
+fun <T, S> S.bip(): String where S : Foo<T>, S: Bar<T> {
+    return "OK"
+}
+
+fun box(): String {
+    val baz = Baz<String>()
+    return baz.bip()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/invokeLambdaAsFunction.fir.kt b/compiler/testData/diagnostics/tests/inference/invokeLambdaAsFunction.fir.kt
new file mode 100644
index 00000000000..5bdbf9a10cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/invokeLambdaAsFunction.fir.kt
@@ -0,0 +1,7 @@
+fun test1(i: Int) = <!UNRESOLVED_REFERENCE!>{ i ->
+    i
+}(i)<!>
+
+fun test2() = <!UNRESOLVED_REFERENCE!>{ i -> i }()<!>
+
+fun test3() = <!UNRESOLVED_REFERENCE!>{ i -> i }(1)<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/knownTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/inference/knownTypeParameters.fir.kt
new file mode 100644
index 00000000000..dcefaaae47b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/knownTypeParameters.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +NewInference
+
+open class A<T1, T2> {
+    open inner class A1(val a1: T1)
+    open inner class A2(val a2: T2)
+
+    open fun f1(arg: T1) = arg
+    open fun f2(arg: T2) = arg
+}
+
+open class B<T> : A<T, Int>() {
+    open inner class B1(b1: T) : <!INAPPLICABLE_CANDIDATE!>A1<!>(b1)
+    open inner class B2(b2: Int) : <!INAPPLICABLE_CANDIDATE!>A2<!>(b2)
+
+    fun variableToKnownParameter(p: T): Int =
+        p as? Int ?: 0
+
+    inner class B3(b3: T) : <!INAPPLICABLE_CANDIDATE!>A2<!>(variableToKnownParameter(b3))
+
+    override fun f1(arg: T) = arg
+    override fun f2(arg: Int) = arg
+}
+
+class C : B<String>() {
+    inner class C1(c1: String): <!INAPPLICABLE_CANDIDATE!>B1<!>(c1)
+    inner class C2 : B2(15)
+
+    override fun f1(arg: String) = arg
+    override fun f2(arg: Int) = arg
+}
diff --git a/compiler/testData/diagnostics/tests/inference/kt11963.fir.kt b/compiler/testData/diagnostics/tests/inference/kt11963.fir.kt
new file mode 100644
index 00000000000..e68a9995bba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt11963.fir.kt
@@ -0,0 +1 @@
+val <T : KClass<T>.something> abc
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt12399.fir.kt b/compiler/testData/diagnostics/tests/inference/kt12399.fir.kt
new file mode 100644
index 00000000000..7bd744df578
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt12399.fir.kt
@@ -0,0 +1,3 @@
+fun foo(a: Any) {
+    foo(<!UNRESOLVED_REFERENCE!>{ index -> } {  }<!>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt1293.fir.kt b/compiler/testData/diagnostics/tests/inference/kt1293.fir.kt
new file mode 100644
index 00000000000..17db113b303
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt1293.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+//KT-1293 Compiler doesn't show error when element of Array<Int?> is assigned to Int
+
+package kt1293
+
+fun main() {
+    val intArray = arrayOfNulls<Int>(10)
+    val i : Int = intArray[0]
+    requiresInt(intArray[0])
+}
+
+fun requiresInt(i: Int) {}
diff --git a/compiler/testData/diagnostics/tests/inference/kt28598.fir.kt b/compiler/testData/diagnostics/tests/inference/kt28598.fir.kt
new file mode 100644
index 00000000000..288e3733bc1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt28598.fir.kt
@@ -0,0 +1,85 @@
+// !WITH_NEW_INFERENCE
+// !IDIAGNOSTICS: -UNUSED_EXPRESSION
+
+fun case_1(a: MutableList<out MutableList<MutableList<MutableList<MutableList<MutableList<MutableList<Int?>?>?>?>?>?>?>?) {
+    if (a != null) {
+        val b = a[0] // no SMARTCAST diagnostic
+        if (b != null) {
+            val c = b[0]
+            if (c != null) {
+                val d = c[0]
+                if (d != null) {
+                    val e = d[0]
+                    if (e != null) {
+                        val f = e[0]
+                        if (f != null) {
+                            val g = f[0]
+                            if (g != null) {
+                                val h = g[0]
+                                if (h != null) {
+                                    h.inc()
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+
+fun case_2(a: MutableList<out MutableList<MutableList<MutableList<out MutableList<MutableList<MutableList<out Int?>?>?>?>?>?>?>?) {
+    if (a != null) {
+        val b = a[0] // no SMARTCAST diagnostic
+        if (b != null) {
+            val c = b[0]
+            if (c != null) {
+                val d = c[0]
+                if (d != null) {
+                    val e = d[0] // no SMARTCAST diagnostic
+                    if (e != null) {
+                        val f = e[0]
+                        if (f != null) {
+                            val g = f[0]
+                            if (g != null) {
+                                val h = g[0] // no SMARTCAST diagnostic
+                                if (h != null) {
+                                    h.inc()
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+
+fun case_3(a: MutableList<MutableList<MutableList<MutableList<MutableList<MutableList<MutableList<Int?>?>?>?>?>?>?>?) {
+    if (a != null) {
+        val b = a[0]
+        if (b != null) {
+            val c = b[0]
+            if (c != null) {
+                val d = c[0]
+                if (d != null) {
+                    val e = d[0]
+                    if (e != null) {
+                        val f = e[0]
+                        if (f != null) {
+                            val g = f[0]
+                            if (g != null) {
+                                val h = g[0]
+                                if (h != null) {
+                                    h.inc()
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt28654.fir.kt b/compiler/testData/diagnostics/tests/inference/kt28654.fir.kt
new file mode 100644
index 00000000000..d9bf315a610
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt28654.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// Related issue: KT-28654
+
+fun <K> select(): K = run { }
+
+fun test() {
+    val x: Int = select()
+    val t = select()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt30405.fir.kt b/compiler/testData/diagnostics/tests/inference/kt30405.fir.kt
new file mode 100644
index 00000000000..b769cf1ff57
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt30405.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ExpectedTypeFromCast
+// !CHECK_TYPE
+// Issue: KT-30405
+
+inline fun <reified T> foo(): T {
+    TODO()
+}
+
+fun test() {
+    val fooCall = foo() as String // T in foo should be inferred to String
+    fooCall checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    val safeFooCall = foo() as? String
+    safeFooCall checkType { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt3184.fir.kt b/compiler/testData/diagnostics/tests/inference/kt3184.fir.kt
new file mode 100644
index 00000000000..db51502b046
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt3184.fir.kt
@@ -0,0 +1,26 @@
+//KT-3184 Type inference seems partially broken
+package a
+
+import java.util.HashMap
+
+private fun <T> test(value: T, extf: String.(value: T)->Unit) {
+    "".<!UNRESOLVED_REFERENCE!>extf<!>(value)
+}
+
+fun main() {
+    test(1, {value -> println(value)})
+}
+
+fun tests() {
+    val dict = HashMap<String, (String) -> Unit>()
+    <!INAPPLICABLE_CANDIDATE!>dict["0"] = { str -> println(str) }<!>
+    <!INAPPLICABLE_CANDIDATE!>dict["1"] = { println(<!UNRESOLVED_REFERENCE!>it<!>) }<!>
+
+    dict.<!INAPPLICABLE_CANDIDATE!>set<!>("1", { println(<!UNRESOLVED_REFERENCE!>it<!>) })
+    <!INAPPLICABLE_CANDIDATE!>dict["1"] = { r -> println(r) }<!>
+}
+
+// from standard library
+operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) : V? = this.put(key, value)
+
+fun println(message : Any?) = System.out.println(message)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt32415.fir.kt b/compiler/testData/diagnostics/tests/inference/kt32415.fir.kt
new file mode 100644
index 00000000000..8aa20cb4c2a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt32415.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +NewInference
+
+abstract class TestType<V: Any> {
+    open inner class Inner(val item: V)
+}
+
+class Derived: TestType<Long>() {
+    inner class DerivedInner(item: Long): <!INAPPLICABLE_CANDIDATE!>Inner<!>(item)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/kt32434.fir.kt b/compiler/testData/diagnostics/tests/inference/kt32434.fir.kt
new file mode 100644
index 00000000000..72c785a37e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt32434.fir.kt
@@ -0,0 +1,32 @@
+// FULL_JDK
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// Issue: KT-32434
+
+// FILE: CacheMonoJava.java
+
+public class CacheMonoJava {
+    public static <K, V> Mono<V> lookup(java.util.Map<K, ? super Signal<? extends V>> map, K key) {
+        throw new UnsupportedOperationException();
+    }
+}
+
+// FILE: main.kt
+
+interface Cache<K, V> {
+    fun asMap(): MutableMap<K, V>
+}
+
+interface Mono<E>
+interface Signal<E> : Mono<E>
+
+interface AttributeDefinition
+
+val cache: Cache<String, Signal<out AttributeDefinition>> = TODO()
+
+object CacheMonoKotlin {
+    fun <K, V> lookup(map: MutableMap<K, in Signal<out V>>, key: K): Mono<V> = TODO()
+}
+
+fun findByName_java(name: String): Mono<AttributeDefinition> = CacheMonoJava.lookup(cache.asMap(), name)
+fun findByName_kotlin(name: String): Mono<AttributeDefinition> = CacheMonoKotlin.lookup(cache.asMap(), name)
diff --git a/compiler/testData/diagnostics/tests/inference/kt6175.fir.kt b/compiler/testData/diagnostics/tests/inference/kt6175.fir.kt
new file mode 100644
index 00000000000..ec110cd53a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt6175.fir.kt
@@ -0,0 +1,49 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+
+fun <T, R : Any> foo(body: (R?) -> T): T = fail()
+
+fun test1() {
+    foo {
+        true
+    }
+    foo { x ->
+        true
+    }
+}
+
+
+fun <T, R> bar(body: (R) -> T): T = fail()
+
+fun test2() {
+    bar {
+        true
+    }
+    bar { x ->
+        true
+    }
+}
+
+fun <T, R> baz(body: (List<R>) -> T): T = fail()
+
+fun test3() {
+    baz {
+        true
+    }
+    baz { x ->
+        true
+    }
+}
+
+fun <T, R : Any> brr(body: (List<R?>) -> T): T = fail()
+
+fun test4() {
+    brr {
+        true
+    }
+    brr { x ->
+        true
+    }
+}
+
+fun fail(): Nothing = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/kt619.fir.kt b/compiler/testData/diagnostics/tests/inference/kt619.fir.kt
new file mode 100644
index 00000000000..34abe88e155
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/kt619.fir.kt
@@ -0,0 +1,4 @@
+class A(t : Int) : Comparable<A> {
+    var i = t
+    override fun compareTo(other : A) = (this.i - other.i)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/lambdaInValInitializerWithAnonymousFunctions.fir.kt b/compiler/testData/diagnostics/tests/inference/lambdaInValInitializerWithAnonymousFunctions.fir.kt
new file mode 100644
index 00000000000..399d26ddc54
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/lambdaInValInitializerWithAnonymousFunctions.fir.kt
@@ -0,0 +1,9 @@
+typealias SuspendFn = suspend () -> Unit
+
+val test1f: suspend () -> Unit = fun () {}
+val test2f: suspend Any.() -> Unit = fun Any.() {}
+
+// This is a bug in the old inference and should be fixed in new inference
+// see "Fix anonymous function literals handling in type checker" for more details
+val test3f: suspend Any.(Int) -> Int = fun (k: Int) = k + 1
+val test4f: SuspendFn = fun Any.() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/listConstructor.fir.kt b/compiler/testData/diagnostics/tests/inference/listConstructor.fir.kt
new file mode 100644
index 00000000000..af1c0fc71be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/listConstructor.fir.kt
@@ -0,0 +1,30 @@
+// !CHECK_TYPE
+
+package a
+//+JDK
+import java.util.*
+
+fun <A> cons(x: A, xs: List<A>): List<A> = xs
+
+fun <B> nil(): List<B> = arrayList()
+
+fun test() {
+    val xs = cons(1, nil())
+    val xs1 = cons("", nil())
+    val xs2 = cons(1, nil<Any>())
+
+    checkSubtype<List<Int>>(xs)
+    checkSubtype<List<String>>(xs1)
+    checkSubtype<List<Any>>(xs2)
+}
+
+
+// ---------------------
+// copy from kotlin util
+
+fun <T> arrayList(vararg values: T) : ArrayList<T> = values.toCollection(ArrayList<T>(values.size))
+
+fun <T, C: MutableCollection<in T>> Array<T>.toCollection(result: C) : C {
+    for (element in this) result.add(element)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/inference/localFunctionInsideIfBlock.fir.kt b/compiler/testData/diagnostics/tests/inference/localFunctionInsideIfBlock.fir.kt
new file mode 100644
index 00000000000..a713982a29e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/localFunctionInsideIfBlock.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +NewInference
+
+fun bar() {
+    if (true) {
+        fun local() {
+        }
+    } else {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/mapFunction.fir.kt b/compiler/testData/diagnostics/tests/inference/mapFunction.fir.kt
new file mode 100644
index 00000000000..b9232a4cf5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/mapFunction.fir.kt
@@ -0,0 +1,35 @@
+// !CHECK_TYPE
+
+package a
+
+//+JDK
+import java.util.*
+
+fun foo() {
+    val v = array(1, 2, 3)
+
+    val u = v map { it * 2 }
+
+    checkSubtype<List<Int>>(u)
+
+    val a = 1..5
+
+    val b = a.map { it * 2 }
+
+    checkSubtype<List<Int>>(b)
+
+    //check for non-error types
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String>(u)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String>(b)
+}
+
+
+// ---------------------
+// copy from kotlin util (but with `infix` modifier on `map`)
+
+@Suppress("UNCHECKED_CAST")
+fun <T> array(vararg t : T) : Array<T> = t as Array<T>
+
+infix fun <T, R> Array<T>.map(transform : (T) -> R) : List<R> {}
+
+infix fun <T, R> Iterable<T>.map(transform : (T) -> R) : List<R> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.fir.kt b/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.fir.kt
new file mode 100644
index 00000000000..5907bf98364
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.fir.kt
@@ -0,0 +1,24 @@
+// !CHECK_TYPE
+
+package i
+
+//+JDK
+import java.util.*
+
+fun <T, R> Collection<T>.map1(f : (T) -> R) : List<R> {}
+fun <T, R> java.lang.Iterable<T>.map1(f : (T) -> R) : List<R> {}
+
+fun test(list: List<Int>) {
+    val res = list.map1 { it }
+    //check res is not of error type
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String>(res)
+}
+
+fun <T> Collection<T>.foo() {}
+fun <T> java.lang.Iterable<T>.foo() {}
+
+fun test1(list: List<Int>) {
+    val res = list.foo()
+    //check res is not of error type
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String>(res)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/arrayAccess.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/arrayAccess.fir.kt
new file mode 100644
index 00000000000..2657debff59
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/arrayAccess.fir.kt
@@ -0,0 +1,11 @@
+package b
+
+class A {
+    operator fun <T> get(i: Int): List<T> = throw Exception("$i")
+}
+
+fun bar(l: List<Int>) = l
+
+fun test(a: A) {
+    bar(a[12])
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/binaryExpressions.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/binaryExpressions.fir.kt
new file mode 100644
index 00000000000..8abe5806286
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/binaryExpressions.fir.kt
@@ -0,0 +1,72 @@
+// !WITH_NEW_INFERENCE
+package h
+
+interface A<T> {}
+
+fun <T> newA(): A<T> = throw Exception()
+
+interface Z
+
+fun <T> id(t: T): T = t
+
+//binary expressions
+//identifier
+infix fun <T> Z.foo(a: A<T>): A<T> = a
+
+fun test(z: Z) {
+    z foo newA()
+    val a: A<Int> = id(z foo newA())
+    val b: A<Int> = id(z.foo(newA()))
+    use(a, b)
+}
+
+//binary operation expression
+operator fun <T> Z.plus(a: A<T>): A<T> = a
+
+fun test1(z: Z) {
+    id(z + newA())
+    val a: A<Z> = z + newA()
+    val b: A<Z> = z.plus(newA())
+    val c: A<Z> = id(z + newA())
+    val d: A<Z> = id(z.plus(newA()))
+    use(a, b, c, d)
+}
+
+//comparison operation
+operator fun <T> Z.compareTo(a: A<T>): Int { use(a); return 1 }
+
+fun test2(z: Z) {
+    val a: Boolean = id(z < newA())
+    val b: Boolean = id(z < newA<Z>())
+    use(a, b)
+}
+
+//'equals' operation
+fun Z.equals(any: Any): Int { use(any); return 1 }
+
+fun test3(z: Z) {
+    z == newA()
+    z == newA<Z>()
+    id(z == newA())
+    id(z == newA<Z>())
+
+    id(z === newA())
+    id(z === newA<Z>())
+}
+
+//'in' operation
+fun test4(collection: Collection<A<*>>) {
+    id(newA() in collection)
+    id(newA<Int>() in collection)
+}
+
+//boolean operations
+fun <T> toBeOrNot(): Boolean = throw Exception()
+
+fun test5() {
+    if (toBeOrNot() && toBeOrNot()) {}
+    if (toBeOrNot<Int>() && toBeOrNot<Int>()) {}
+}
+
+//use
+fun use(vararg a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/checkTypesForQualifiedProperties.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/checkTypesForQualifiedProperties.fir.kt
new file mode 100644
index 00000000000..ef4e3dfba39
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/checkTypesForQualifiedProperties.fir.kt
@@ -0,0 +1,9 @@
+package a
+
+fun test(c: C) {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(c.b)
+}
+
+fun foo(s: String) = s
+
+class C(val b: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsForArraySetExpression.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsForArraySetExpression.fir.kt
new file mode 100644
index 00000000000..583ec9f7104
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsForArraySetExpression.fir.kt
@@ -0,0 +1,8 @@
+fun <T> foo(t: T) = t
+
+fun test(map: MutableMap<Int, Int>, t: Int) {
+    map [t] = foo(t) // t was marked with black square
+}
+
+//from library
+operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) : V? = this.put(key, value)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsInference.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsInference.fir.kt
new file mode 100644
index 00000000000..eea79c7bf82
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsInference.fir.kt
@@ -0,0 +1,19 @@
+package a
+
+import java.util.ArrayList
+
+public fun <T> Iterable<T>.withIndices(): List<Pair<Int, T>> {
+    val answer = ArrayList<Pair<Int, T>>()
+    var nextIndex = 1
+    for (e in this) {
+        answer.add(Pair(nextIndex, e))
+        nextIndex++
+    }
+    return answer
+}
+
+//from standard library
+public class Pair<out A, out B>(
+    public val first: A,
+    public val second: B
+)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedForVariableAsFunctionCall.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedForVariableAsFunctionCall.fir.kt
new file mode 100644
index 00000000000..93fafdcf02d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedForVariableAsFunctionCall.fir.kt
@@ -0,0 +1,16 @@
+package j
+
+interface MyFunc<T> {}
+
+class A(val b: B) {
+}
+
+class B {
+    operator fun <T> invoke(f: (T) -> T): MyFunc<T> = throw Exception()
+}
+
+fun <R> id(r: R) = r
+
+fun foo(a: A) {
+    val r : MyFunc<Int> = id (a.b { x -> x + 14 })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/externalTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/externalTypeParameter.fir.kt
new file mode 100644
index 00000000000..f2f16c4c3b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/externalTypeParameter.fir.kt
@@ -0,0 +1,6 @@
+class A<T> {
+    fun <S> foo(s: S): S = s
+    fun <U> bar(s: U): List<T> = null!!
+
+    fun test() = foo(bar(""))
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/inferenceForNestedBinaryCall.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/inferenceForNestedBinaryCall.fir.kt
new file mode 100644
index 00000000000..df887b2f1c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/inferenceForNestedBinaryCall.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+package aaa
+
+infix fun <T> T.foo(t: T) = t
+
+fun <T> id(t: T) = t
+
+fun a() {
+    val i = id(2 foo 3)
+    checkSubtype<Int>(i) // i shouldn't be resolved to error element
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/kt3395.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/kt3395.fir.kt
new file mode 100644
index 00000000000..41a96b8a2eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/kt3395.fir.kt
@@ -0,0 +1,35 @@
+//KT-3395 mapOf function can't be used as literal
+package b
+
+import java.util.ArrayList
+
+public fun <T> query(t: T, args: Map<String, Any>): List<T> {
+    return ArrayList<T>()
+}
+
+fun test(pair: Pair<String, Int>) {
+    val id = "Hello" // variable is marked as unused
+
+    println("Some" + query(0, mapOf(id to 1)))
+
+    println("Some" + query(0, mapOf(pair)))
+}
+
+
+//from standard library
+fun <K, V> mapOf(vararg values: Pair<K, V>): Map<K, V> { throw Exception() }
+
+infix fun <A,B> A.to(that: B): Pair<A, B> { throw Exception() }
+
+fun println(message : Any?) { throw Exception() }
+
+class Pair<out A, out B> () {}
+
+//short example
+fun <T> foo(t: T) = t
+
+fun test(t: String) {
+
+    println("Some" + foo(t)) // t was marked with black square
+}
+
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/kt3461checkTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/kt3461checkTypes.fir.kt
new file mode 100644
index 00000000000..ec9c0298aeb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/kt3461checkTypes.fir.kt
@@ -0,0 +1,15 @@
+//KT-3461 Nullable argument allowed where shouldn't be
+package a
+
+class F {
+    fun p(): String? = null
+}
+
+fun foo(s: String) {}
+
+fun r(): Int? = null
+
+fun test() {
+    foo(F().p())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(r())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/makeNullableIfSafeCall.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/makeNullableIfSafeCall.fir.kt
new file mode 100644
index 00000000000..7c4b7fe3e78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/makeNullableIfSafeCall.fir.kt
@@ -0,0 +1,41 @@
+package a
+
+interface A {
+    val b: B
+    val nb: B?
+}
+
+interface B {
+    fun foo(): Int
+}
+
+fun test(u: A?, x: A?, y: A?, z: A?, w: A, v: A?) {
+    u?.b?.foo()!! // was UNNECESSARY_SAFE_CALL everywhere, because result type (of 'foo()') wasn't made nullable
+    u!!.b?.foo()!!
+    x?.b!!.foo()!!
+    // x?.b is not null
+    x!!.b!!.foo()!!
+
+    y?.nb?.foo()!!
+    y!!.nb?.foo()!!
+    z?.nb!!.foo()!!
+    // z?.nb is not null
+    z!!.nb!!.foo()!!
+
+    w.b?.foo()!!
+    w.b!!.foo()!!
+    w.nb?.foo()!!
+    w.nb!!.foo()!!
+
+    v!!.b.foo()!!
+}
+
+fun B?.bar(): Int = 1
+fun B?.baz(): Int? = 1
+
+fun doInt(i: Int) = i
+
+fun test(a: A?) {
+    doInt(a?.b.bar()!!)
+    doInt(a?.b.baz()!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/nontrivialCallExpression.fir.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/nontrivialCallExpression.fir.kt
new file mode 100644
index 00000000000..8ca1f233a12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/nontrivialCallExpression.fir.kt
@@ -0,0 +1,18 @@
+package a
+
+fun foo(l: List<Int>): Int = l.get(0)
+
+fun <T> emptyList(): List<T> = throw Exception()
+
+fun <T: Any> makeNullable(t: T): T? = null
+
+fun bar(i: Int) = i
+fun bar(a: Any) = a
+
+fun test(array: Array<Int>) {
+    bar(array[foo(emptyList())])
+
+    bar(foo(emptyList()) + foo(a.emptyList()))
+
+    bar(makeNullable(foo(emptyList())) ?: 0)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/noInformationForParameter.fir.kt b/compiler/testData/diagnostics/tests/inference/noInformationForParameter.fir.kt
new file mode 100644
index 00000000000..1c9eed8c115
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/noInformationForParameter.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+package noInformationForParameter
+//+JDK
+
+import java.util.*
+
+fun test() {
+    val n = newList()
+
+    val n1 : List<String> = newList()
+}
+
+fun <S> newList() : ArrayList<S> {
+    return ArrayList<S>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/complexDependancyOnVariableWithTrivialConstraint.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/complexDependancyOnVariableWithTrivialConstraint.fir.kt
new file mode 100644
index 00000000000..6e5b1719e8f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/complexDependancyOnVariableWithTrivialConstraint.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// Validation test.
+// Check that type variable is fixed to Data<Nothing> as it's used in input types for lambda
+
+class Data<T>(val x: T) {
+    fun dataMethod() {}
+}
+
+fun <K> bar(x: K, y: (K) -> Unit) {}
+
+fun test() {
+    bar(Data(null)) { it.dataMethod() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/generateConstraintWithInnerNothingType.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/generateConstraintWithInnerNothingType.fir.kt
new file mode 100644
index 00000000000..e387e3f09bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/generateConstraintWithInnerNothingType.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Out<out T>(val o: T)
+
+interface Base
+class Inv<K> : Base
+
+fun <S> select(x: S, y: S): S = x
+
+fun test(a1: Inv<Number>, a2: Inv<Nothing?>): Out<Base> {
+    return select(Out(a1), Out(a2))
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/implicitNothingConstraintFromReturn.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/implicitNothingConstraintFromReturn.fir.kt
new file mode 100644
index 00000000000..35389378196
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/implicitNothingConstraintFromReturn.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Simple
+
+fun test(s: Simple?): Simple? {
+    myRun {
+        s?.let { return it }
+    }
+
+    return s
+}
+
+inline fun <R> myRun(block: () -> R): R = TODO()
+inline fun <K, V> K.let(block: (K) -> V): V = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/kt24490.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/kt24490.fir.kt
new file mode 100644
index 00000000000..e51d9a63070
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/kt24490.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun <T> bar(i: T): T = i
+fun foo(i: Int) = i
+
+fun dontRun(body: () -> Unit) = Unit
+
+class Case1 {
+    fun test() {
+        dontRun { val x = bar(bar { -> bar { -> 2} }) }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/kt32051.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/kt32051.fir.kt
new file mode 100644
index 00000000000..7bd6b74bcd0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/kt32051.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+interface LevelA
+interface LevelB : LevelA
+
+class BiType<out X, out Y> {
+    fun <X> pullXb(x: X): BiType<X, LevelB> = TODO()
+    fun <Y> pullYb(y: Y): BiType<LevelB, Y> = TODO()
+    fun <X> pullXn(x: X): BiType<X, Nothing> = TODO()
+    fun <Y> pullYn(y: Y): BiType<Nothing, Y> = TODO()
+}
+
+fun <X> adjustIt(fn: () -> X): X = TODO()
+fun <X> adjustIt(f1: () -> X, f2: () -> X): X = TODO()
+
+fun <X> callAdjustIt(t: BiType<*, *>, x: X, level: LevelA) {
+    val x1 = adjustIt({ t.pullXb(x) })
+
+    x1
+
+    val x2 = adjustIt({ t.pullXn(x) })
+
+    x2
+
+    val x3 = adjustIt({ t.pullXb(x) }, { t.pullYb(level) })
+
+    x3
+
+    val x4 = adjustIt({ t.pullXn(x) }, { t.pullYn(level) })
+
+    x4
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/kt32081.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/kt32081.fir.kt
new file mode 100644
index 00000000000..005db4646cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/kt32081.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> select(x: T, y: T): T = x
+
+fun foo(x: Int, stringNothing: Out2<String, Nothing>): Out2<String, Int> =
+    select(x.right(), stringNothing)
+
+fun <R> R.right(): Out2<Nothing, R> = TODO()
+
+class Out2<out K, out V>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/kt32207.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/kt32207.fir.kt
new file mode 100644
index 00000000000..aff2fa3512d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/kt32207.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Test<X, T> {
+    fun hereIdeaFail(values : List<Int>, others : List<String>): List<Test<out Int, out String>> {
+        return values.map { left(it) }.plus(others.map { right(it) })
+    }
+
+    companion object {
+        fun <L> left(left: L): Test<L, Nothing> = TODO()
+        fun <R> right(right: R): Test<Nothing, R> = TODO()
+    }
+}
+
+fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> = TODO()
+operator fun <T> Collection<T>.plus(elements: Iterable<T>): List<T> = TODO()
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/kt32388.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/kt32388.fir.kt
new file mode 100644
index 00000000000..8a83e051a21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/kt32388.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+
+fun <A, B> Either<A, B>.recover(f: (A) -> B): Either<A, B> = when (this) {
+    is Either.Left -> <!INAPPLICABLE_CANDIDATE!>f<!>(this.a).<!INAPPLICABLE_CANDIDATE!>right<!>()
+    is Either.Right -> this
+}
+
+fun <A> A.right(): Either<Nothing, A> = Either.Right(this)
+
+sealed class Either<out A, out B> {
+    class Left<out A> constructor(val a: A) : Either<A, Nothing>()
+    class Right<out B> constructor(val b: B) : Either<Nothing, B>()
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/lambdaNothingAndExpectedType.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/lambdaNothingAndExpectedType.fir.kt
new file mode 100644
index 00000000000..f2eec49bdec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/lambdaNothingAndExpectedType.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun <K> select2(x: K, y: K): K = TODO()
+fun <K> select3(x: K, y: K, z: K): K = TODO()
+
+fun test2(f: ((String) -> Int)?) {
+    val a0: ((Int) -> Int)? = select2({ it -> it }, null)
+    val b0: ((Nothing) -> Unit)? = select2({ it -> it }, null)
+
+    select3({ <!UNRESOLVED_REFERENCE!>it<!>.<!UNRESOLVED_REFERENCE!>length<!> }, f, null)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/nestedLambdaInferenceWithIncorporationOfVariables.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/nestedLambdaInferenceWithIncorporationOfVariables.fir.kt
new file mode 100644
index 00000000000..f784b2bae38
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/nestedLambdaInferenceWithIncorporationOfVariables.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +NewInference
+
+fun <K> id1(k: K): K = k
+fun <V> id2(v: V): V = v
+
+fun test() {
+    id1 {
+        id2 {
+            3
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/nothingWithCallableReference.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/nothingWithCallableReference.fir.kt
new file mode 100644
index 00000000000..5f2cd7c5e9a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/nothingWithCallableReference.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <K> select2(x: K, y: K): K = TODO()
+fun <K> select3(x: K, y: K, z: K): K = TODO()
+
+fun <K : S, S> dependantSelect2(x: K, y: S) {}
+fun <K : S, S> dependantSelect3(x: K, y: K, z: S) {}
+
+fun foo() {}
+fun cloneFoo() {}
+fun bar(x: Int) {}
+
+fun test(f1: (Int) -> Unit, f2: kotlin.Function1<Int, Unit>) {
+    select2(null, ::foo)
+    select3(null, f1, ::bar)
+    select3(null, f2, ::bar)
+
+    select3(null, f1, ::foo)
+    select3(null, f2, ::foo)
+
+    dependantSelect2(null, ::foo)
+    dependantSelect3(null, ::foo, ::cloneFoo)
+    dependantSelect3(null, f1, ::bar)
+    dependantSelect3(null, ::bar, f1)
+
+    dependantSelect3(null, ::foo, ::bar)
+    dependantSelect3(null, ::bar, ::foo)
+    dependantSelect3(null, f1, ::foo)
+    dependantSelect3(null, ::foo, f1)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/nothingType/platformNothingAsUsefulConstraint.fir.kt b/compiler/testData/diagnostics/tests/inference/nothingType/platformNothingAsUsefulConstraint.fir.kt
new file mode 100644
index 00000000000..caa0b712e6a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nothingType/platformNothingAsUsefulConstraint.fir.kt
@@ -0,0 +1,35 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: Tasks.java
+
+public class Tasks {
+    public static <T> Inv<T> call(JSam<T> f) {
+        return null;
+    }
+}
+
+// FILE: JSam.java
+
+public interface JSam<V> {
+    V call();
+}
+
+// FILE: test.kt
+
+fun <K> withLock(g: () -> K): K = g()
+
+class Out<out P>
+class Inv<S>
+
+fun <R> Inv<R>.asOut(): Out<R> = TODO()
+
+fun test() {
+    val o: Out<Int> = Tasks.call {
+        withLock { TODO() }
+    }.asOut()
+
+    Tasks.call {
+        withLock { TODO() }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nullableTypeArgumentWithNotNullUpperBound.fir.kt b/compiler/testData/diagnostics/tests/inference/nullableTypeArgumentWithNotNullUpperBound.fir.kt
new file mode 100644
index 00000000000..94716e1b394
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nullableTypeArgumentWithNotNullUpperBound.fir.kt
@@ -0,0 +1,11 @@
+fun <S : Any> foo(x: Array<out S?>, y: Array<in S?>) {
+    val xo = <!INAPPLICABLE_CANDIDATE!>outA<!>(x)
+    val yo = inA(y)
+
+    var f: Array<S> = xo
+    f = yo
+}
+
+
+fun <X : Any> outA(x: Array<out X?>): Array<X> = TODO()
+fun <Y : Any> inA(x: Array<in Y?>): Array<Y> = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nullableUpperBound.fir.kt b/compiler/testData/diagnostics/tests/inference/nullableUpperBound.fir.kt
new file mode 100644
index 00000000000..c5cc05a8612
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/nullableUpperBound.fir.kt
@@ -0,0 +1,9 @@
+package o
+
+fun foo(): String? {
+    return accept(JV<String?, Unit?>())
+}
+
+fun <R, D> accept(v: JV<R, D>): R? = null
+
+open class JV<R, D>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/opposite.fir.kt b/compiler/testData/diagnostics/tests/inference/opposite.fir.kt
new file mode 100644
index 00000000000..842dfeb34d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/opposite.fir.kt
@@ -0,0 +1,11 @@
+package a
+
+interface Persistent
+interface PersistentFactory<T>
+
+class Relation<Source: Persistent, Target: Persistent>(
+        val sources: PersistentFactory<Source>,
+        val targets: PersistentFactory<Target>
+) {
+    fun opposite() = Relation(targets, sources)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/possibleCycleOnConstraints.fir.kt b/compiler/testData/diagnostics/tests/inference/possibleCycleOnConstraints.fir.kt
new file mode 100644
index 00000000000..9a3c0019831
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/possibleCycleOnConstraints.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+package a
+
+import java.util.*
+
+fun <T> g (f: () -> List<T>) : T {}
+
+fun test() {
+    //here possibly can be a cycle on constraints
+    val x = g { Collections.emptyList() }
+
+    val y = g<Int> { Collections.emptyList() }
+    val z : List<Int> = g { Collections.emptyList() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/recursiveCalls/kt23531.fir.kt b/compiler/testData/diagnostics/tests/inference/recursiveCalls/kt23531.fir.kt
new file mode 100644
index 00000000000..8c06c32ec28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/recursiveCalls/kt23531.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+class Scope
+
+fun <T> simpleAsync0(block: Scope.() -> T) {}
+fun <T> simpleAsync1(block: suspend Scope.() -> T) {}
+suspend fun <T> simpleAsync2(block: Scope.() -> T) {}
+suspend fun <T> simpleAsync3(block: suspend Scope.() -> T) {}
+
+fun insideJob0() = doTheJob0()
+fun insideJob1() = doTheJob1()
+suspend fun insideJob2() = doTheJob2()
+suspend fun insideJob3() = doTheJob3()
+
+fun doTheJob0() = simpleAsync0 { insideJob0() }
+fun doTheJob1() = simpleAsync1 { insideJob1() }
+suspend fun doTheJob2() = simpleAsync2 { insideJob2() }
+suspend fun doTheJob3() = simpleAsync3 { insideJob3() }
diff --git a/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/localFactorial.fir.kt b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/localFactorial.fir.kt
new file mode 100644
index 00000000000..f74f7cd9f22
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/localFactorial.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// See KT-6271
+fun foo() {
+    fun fact(n: Int) = {
+        if (n > 0) {
+            fact(n - 1) <!UNRESOLVED_REFERENCE!>*<!> n
+        }
+        else {
+            1
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/recursiveFun.fir.kt b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/recursiveFun.fir.kt
new file mode 100644
index 00000000000..def59b45ae8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/recursiveFun.fir.kt
@@ -0,0 +1,4 @@
+// !WITH_NEW_INFERENCE
+fun foo() {
+    fun bar() = (fun() = bar())
+}
diff --git a/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/recursiveLambda.fir.kt b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/recursiveLambda.fir.kt
new file mode 100644
index 00000000000..ffe65d1b70d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/recursiveLambda.fir.kt
@@ -0,0 +1,6 @@
+// !WITH_NEW_INFERENCE
+fun foo() {
+    fun bar() = {
+        bar()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/selfCall.fir.kt b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/selfCall.fir.kt
new file mode 100644
index 00000000000..4bddc08a208
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/recursiveLocalFuns/selfCall.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+fun foo() {
+    fun bar1() = bar1()
+
+    fun bar2() = 1 + bar2()
+    fun bar3() = <!INAPPLICABLE_CANDIDATE!>id<!>(bar3())
+}
+
+fun <T> id(x: T) = x
diff --git a/compiler/testData/diagnostics/tests/inference/recursiveTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/recursiveTypes.fir.kt
new file mode 100644
index 00000000000..b8aabee4db1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/recursiveTypes.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+// !WITH_NEW_INFERENCE
+
+interface RecursiveGeneric<T : RecursiveGeneric<T, U>, U>
+
+class A : RecursiveGeneric<A, Int>
+class B : RecursiveGeneric<B, Int>
+class C : RecursiveGeneric<C, Unit>
+
+fun <K> select(x: K, y: K): K = x
+
+fun foo(a: A, b: B, c: C) {
+    select(a, b)
+    select(a, c)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/compareBy.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/compareBy.fir.kt
new file mode 100644
index 00000000000..cb18881e8f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/compareBy.fir.kt
@@ -0,0 +1,9 @@
+class Item(val name: String, val rating: Int): Comparable<Item> {
+    public override fun compareTo(other: Item): Int {
+        return compareBy(this, other, { rating }, { name })
+    }
+}
+
+// from standard library
+fun <T : Any> compareBy(a: T?, b: T?,
+                               vararg functions: T.() -> Comparable<*>?): Int = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1029.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1029.fir.kt
new file mode 100644
index 00000000000..3d020b79bfd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1029.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+//KT-1029 Wrong type inference
+package i
+
+public fun<T> from(yielder: ()->Iterable<T>) : Iterable<T> {
+}
+
+public infix fun<T> Iterable<T>.where(predicate : (T)->Boolean) : ()->Iterable<T> {
+}
+
+fun a() {
+    val x = 0..200
+    val odd = from (x where {it%2==0}) // I believe it should infer here
+
+    checkSubtype<Iterable<Int>>(odd)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1031.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1031.fir.kt
new file mode 100644
index 00000000000..5574b422d33
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1031.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+
+//KT-1031 Can't infer type of `it` with two lambdas
+package i
+
+import java.util.ArrayList
+
+public infix fun<TItem> Iterable<TItem>.where(predicate : (TItem)->Boolean) : ()->Iterable<TItem> {
+}
+
+public fun<TItem, TResult> select(yielder: ()->Iterable<TItem>, selector : (TItem)->TResult) : ()->Iterable<TResult> {
+}
+
+fun a() {
+    val x = 0..200
+    val z = x where { i: Int -> i % 2 == 0 }
+    val yielder = select(x where { it%2==0 }, { it.toString() })
+
+    checkSubtype<() -> Iterable<Int>>(z)
+    checkSubtype<() -> Iterable<String>>(yielder)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1127.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1127.fir.kt
new file mode 100644
index 00000000000..bef26ff67bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1127.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+//KT-1127 Wrong type computed for Arrays.asList()
+
+package d
+
+fun <T> asList(t: T) : List<T>? {}
+
+fun main() {
+    val list : List<String> = asList("")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1145.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1145.fir.kt
new file mode 100644
index 00000000000..c4a1ff3b486
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1145.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+//KT-1145 removing explicit generics on a call to Iterable<T>.map(...) seems to generate an odd bytecode/runtime error
+
+package d
+
+fun test(numbers: Iterable<Int>) {
+    val s = numbers.map{it.toString()}.fold(""){it, it2 -> it + it2}
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(s)
+}
+
+//from library
+fun <T, R> Iterable<T>.map(transform : (T) -> R) : List<R> {}
+
+fun <T> Iterable<T>.fold(initial: T, operation: (T, T) -> T): T {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1358.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1358.fir.kt
new file mode 100644
index 00000000000..47f48ec856f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1358.fir.kt
@@ -0,0 +1,12 @@
+//KT-1358 Overload resolution ambiguity with smartcast and generic function
+package d
+
+fun bar(a: Any?) {
+    if (a != null) {
+        a.foo() //overload resolution ambiguity
+        a.sure() //overload resolution ambiguity
+    }
+}
+
+fun <T : Any> T?.foo() {}
+fun <T : Any> T?.sure() : T = this!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1410.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1410.fir.kt
new file mode 100644
index 00000000000..56da5d551cd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1410.fir.kt
@@ -0,0 +1,26 @@
+// !CHECK_TYPE
+
+// KT-1410 Compiler does automatically infer type argument when using variance
+//+JDK
+package d
+
+public fun <T> MutableCollection<out T>.filterToMy(result : MutableList<in T>, filter : (T) -> Boolean) : MutableCollection<out T> {
+    for (t in this){
+        if (filter(t)){
+            result.add(t)
+        }
+    }
+    return this
+}
+
+fun foo(result: MutableList<in String>, collection: MutableCollection<String>, prefix : String){
+    collection.filterToMy(result, {it.startsWith(prefix)})
+}
+
+fun test(result: MutableList<in Any>, collection: MutableCollection<String>, prefix : String){
+    val c = collection.filterToMy(result, {it.startsWith(prefix)})
+    checkSubtype<MutableCollection<out String>>(c)
+}
+
+//from library
+fun String.startsWith(prefix: String) : Boolean {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1718.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1718.fir.kt
new file mode 100644
index 00000000000..1fbdb53e7c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1718.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+//KT-1718 compiler error when not using temporary variable
+package n
+
+import java.util.ArrayList
+
+fun test() {
+    val list = arrayList("foo", "bar") + arrayList("cheese", "wine")
+    checkSubtype<List<String>>(list)
+    //check it's not an error type
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(list)
+}
+
+//from library
+fun <T> arrayList(vararg values: T) : ArrayList<T> {}
+operator fun <T> Iterable<T>.plus(elements: Iterable<T>): List<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt1944.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt1944.fir.kt
new file mode 100644
index 00000000000..518a6096516
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt1944.fir.kt
@@ -0,0 +1,14 @@
+// !CHECK_TYPE
+
+//KT-1944 Inference fails on run()
+package j
+
+class P {
+    var x : Int = 0
+        private set
+
+    fun foo() {
+        val r = run {x = 5} // ERROR
+        checkSubtype<Unit>(r)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2057.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2057.fir.kt
new file mode 100644
index 00000000000..27e53675870
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2057.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import java.util.ArrayList
+
+fun <T> foo(a : T, b : Collection<T>, c : Int) {
+}
+
+fun <T> arrayListOf(vararg values: T): ArrayList<T> = throw Exception("$values")
+
+val bar = <!INAPPLICABLE_CANDIDATE!>foo<!>("", arrayListOf(), )
+val bar2 = <!INAPPLICABLE_CANDIDATE!>foo<!><String>("", arrayListOf(), )
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2179.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2179.fir.kt
new file mode 100644
index 00000000000..5e0aa34d03d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2179.fir.kt
@@ -0,0 +1,46 @@
+// !CHECK_TYPE
+
+//KT-2179 Nested function literal breaks compiler
+package i
+
+//+JDK
+import java.util.*
+
+fun test() {
+    val sample1: List<List<Int?>> = arrayList(arrayList<Int?>(1, 7, null, 8))
+
+    //breaks compiler
+    val sample2 = sample1.map({it.map({it})})
+    checkSubtype<List<List<Int?>>>(sample2)
+
+    //breaks compiler
+    val sample3 = sample1.map({row -> row.map({column -> column})})
+    checkSubtype<List<List<Int?>>>(sample3)
+
+    //doesn't break compiler
+    val identity: (Int?) -> Int? = {column -> column}
+    val sample4 = sample1.map({row -> row.map(identity)})
+    checkSubtype<List<List<Int?>>>(sample4)
+}
+
+//------------
+
+fun <T> arrayList(vararg values: T) : ArrayList<T> = values.toCollection(ArrayList<T>(values.size))
+
+fun <T, R> Collection<T>.map(transform : (T) -> R) : List<R> {
+    return <!INAPPLICABLE_CANDIDATE!>mapTo<!>(java.util.<!UNRESOLVED_REFERENCE!>ArrayList<!><R>(this.size), transform)
+}
+
+fun <T, R, C: MutableCollection<in R>> Collection<T>.mapTo(result: C, transform : (T) -> R) : C {
+  for (item in this)
+    result.add(transform(item))
+  return result
+}
+
+fun <T, C: MutableCollection<in T>> Array<T>.toCollection(result: C) : C {
+    for (element in this) result.add(element)
+    return result
+}
+
+val Collection<*>.size : Int
+    get() = size
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2200.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2200.fir.kt
new file mode 100644
index 00000000000..ce35fed156d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2200.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+//KT-2200 array(array()) breaks compiler
+package n
+
+fun main() {
+    val a = array(array())
+    val a0 : Array<Array<Int>> = array(array())
+    val a1 = array(array<Int>())
+    checkSubtype<Array<Array<Int>>>(a1)
+    val a2 = array<Array<Int>>(array())
+    checkSubtype<Array<Array<Int>>>(a2)
+}
+
+//from library
+@Suppress("UNCHECKED_CAST")
+fun <T> array(vararg t : T) : Array<T> = t as Array<T>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2283.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2283.fir.kt
new file mode 100644
index 00000000000..e64755422b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2283.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+//KT-2283 Bad diagnostics of failed type inference
+package a
+
+
+interface Foo<A>
+
+fun <A, B> Foo<A>.map(f: (A) -> B): Foo<B> = object : Foo<B> {}
+
+
+fun foo() {
+    val l: Foo<String> = object : Foo<String> {}
+    val m: Foo<String> = l.map { ppp -> 1 }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2286.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2286.fir.kt
new file mode 100644
index 00000000000..dc8b9a5cb70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2286.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// KT-2286 Improve error message for nullability check failure for extension methods
+
+package n
+
+abstract class Buggy {
+
+    abstract val coll : Collection<Int>
+
+    fun getThree(): Int? {
+        return coll.find{ it > 3 }  // works fine
+    }
+
+    val anotherThree : Int
+        get() = coll.find{ it > 3 } // does not work here
+
+    val yetAnotherThree : Int
+        get() = coll.find({ v:Int -> v > 3 }) // neither here
+
+    val extendedGetter : Int
+        get() {
+            return coll.find{ it > 3 }  // not even here!
+        }
+
+}
+
+//from library
+fun <T: Any> Iterable<T>.find(predicate: (T) -> Boolean) : T? {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2294.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2294.fir.kt
new file mode 100644
index 00000000000..c5e4fa5eb02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2294.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+//KT-2294 Type inference infers DONT_CARE instead of correct type
+package a
+
+public fun <E> foo(array: Array<E>): Array<E> = array
+
+public fun test()
+{
+    val x = foo(array(1, 2, 3, 4, 5)) // Should infer type 'Int'
+    //            ^--- public final fun <T : kotlin.Any? > array(vararg t : DONT_CARE) : kotlin.Array<DONT_CARE> defined in Kotlin
+    //       ^--- public final fun <E : kotlin.Any? > foo(items t : kotlin.Array<DONT_CARE>) : kotlin.Array<DONT_CARE> defined in root package
+    checkSubtype<Array<Int>>(x)
+}
+
+//--------------------
+@Suppress("UNCHECKED_CAST")
+fun <T> array(vararg t : T) : Array<T> = t as Array<T>
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2320.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2320.fir.kt
new file mode 100644
index 00000000000..b132028c344
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2320.fir.kt
@@ -0,0 +1,13 @@
+//KT-2320 failure of complex case of type inference
+package i
+
+interface NotMap<B>
+
+interface Entry<B> {
+    fun getValue(): B
+}
+
+
+fun <V, R> NotMap<V>.mapValuesOriginal(ff: (Entry<V>) -> R): NotMap<R> = throw Exception()
+
+fun <B, C> NotMap<B>.mapValuesOnly(f: (B) -> C) = mapValuesOriginal { e -> f(e.getValue()) }
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2324.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2324.fir.kt
new file mode 100644
index 00000000000..5ff13eabd11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2324.fir.kt
@@ -0,0 +1,35 @@
+// !CHECK_TYPE
+
+//KT-2324 Can't resolve generic by type of function result
+package i
+
+//+JDK
+import java.util.*
+
+fun <T, K> someFunction(list: List<T>, transform: (T) -> K): List<K> {
+    val result = arrayList<K>()
+    for (i in list) {
+        result.add(transform(i))
+    }
+    return result
+}
+
+fun testSomeFunction() {
+    val result1 = someFunction(arrayList<Int>(1, 2), {checkSubtype<Int>(it)}) //type of result1 is List<Int>
+    assertEquals(1, result1.get(0)); //OK
+
+    val result2 = someFunction(arrayList<Int>(1, 2), {it}) // type of result2 is List<DONT_CARE>
+    checkSubtype<List<Int>>(result2)
+    assertEquals(1, result2.get(0)); //resolved to error element
+}
+
+//---------------------------------
+fun assertEquals(expected: Any?, actual: Any?, message: String = "") {
+}
+
+fun <T> arrayList(vararg values: T) : ArrayList<T> = values.toCollection(ArrayList<T>(values.size))
+
+fun <T, C: MutableCollection<in T>> Array<T>.toCollection(result: C) : C {
+    for (element in this) result.add(element)
+    return result
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2407.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2407.fir.kt
new file mode 100644
index 00000000000..836e667aec3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2407.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+package n
+
+import java.util.*
+
+fun test() {
+    val foo = arrayList("").map { it -> it.length }.fold(0, { x, y -> Math.max(x, y) })
+    checkSubtype<Int>(foo)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String>(foo)
+}
+
+//from library
+fun <T> arrayList(vararg values: T) : ArrayList<T> {}
+
+fun <T, R> Collection<T>.map(transform : (T) -> R) : List<R> {}
+
+fun <T> Iterable<T>.fold(initial: T, operation: (T, T) -> T): T {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2445.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2445.fir.kt
new file mode 100644
index 00000000000..2cef6dc4105
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2445.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+//KT-2445 Calling method with function with generic parameter causes compile-time exception
+package a
+
+fun main() {
+    test {
+
+    }
+}
+
+fun <R> test(callback: (R) -> Unit):Unit = callback(null!!)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2459.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2459.fir.kt
new file mode 100644
index 00000000000..4e0e772278b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2459.fir.kt
@@ -0,0 +1,10 @@
+//KT-2459 Type inference error
+package b
+
+import java.util.*
+
+class B<T>(val x: List<T>)
+fun <T> f(x: T): B<T> = B(arrayList(x))
+
+// from standard library
+fun <T> arrayList(vararg values: T) : ArrayList<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2484.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2484.fir.kt
new file mode 100644
index 00000000000..6071cfac1b9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2484.fir.kt
@@ -0,0 +1,18 @@
+//KT-2484 Type inferred for function literal is (...) -> Int instead of (...) -> Unit, when function literal parameter is explicit 
+
+package a
+//+JDK
+
+fun <T> Array<T>.forEach(operation: (T) -> Unit) : Unit { for (element in this) operation(element) }
+
+fun bar(operation: (String) -> Unit) = operation("")
+
+fun main(args: Array<String>) {
+    args.forEach { a : String -> a.length } // Type mismatch: (String) -> Unit required, (String) -> Int found
+    args.forEach { a -> a.length } // Type mismatch: (String) -> Unit required, (String) -> Int found
+    args.forEach { it.length }     // This works!
+
+    bar { a: String -> a.length }
+    bar { a -> a.length }
+    bar { it.length }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2505.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2505.fir.kt
new file mode 100644
index 00000000000..510d55c6d3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2505.fir.kt
@@ -0,0 +1,22 @@
+// !CHECK_TYPE
+
+//KT-2505 Type mismatch: inferred type is T but T was expected
+
+package a
+
+interface MyType {}
+class MyClass<T> : MyType {}
+
+public open class HttpResponse() {
+    public open fun <T> parseAs(dataClass : MyClass<T>) : T {
+        throw Exception()
+    }
+    public open fun parseAs(dataType : MyType) : Any? {
+        return null
+    }
+}
+
+fun <R> test (httpResponse: HttpResponse, rtype: MyClass<R>) {
+    val res = httpResponse.parseAs( rtype )
+    checkSubtype<R>(res) //type mismatch: required R, found T
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2514.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2514.fir.kt
new file mode 100644
index 00000000000..1dff03baa7a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2514.fir.kt
@@ -0,0 +1,16 @@
+//KT-2514 Type inference fails when using extension function literal
+package kt2514
+
+//+JDK
+import java.io.Closeable
+
+fun <T> Thread.use(block: Thread.() -> T): T = <!INAPPLICABLE_CANDIDATE!>block<!>()
+
+fun <T: Closeable, R> T.use(block: (T)-> R) : R = block(this)
+
+fun main() {
+    Thread().use { }            // compilation error: Type inference failed
+    Thread().use { 5 + 5 }      // compilation error: Type inference failed
+    Thread().use<Unit> { }      // compiles okay
+    Thread().use<Int> { 5 + 5 } // compiles okay
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2588.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2588.fir.kt
new file mode 100644
index 00000000000..bfe802621b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2588.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+//T-2588 Allow to specify exact super type (expected) in inference if many
+
+import java.util.HashSet
+
+class MyClass<T>()
+
+interface A
+interface D
+class B : A, D
+class C : A, D
+
+fun <T> hashSetOf(vararg values: T): HashSet<T> = throw Exception("$values")
+
+fun foo(b: MyClass<B>, c: MyClass<C>) {
+    val set1 : Set<MyClass<out D>> = hashSetOf(b, c) //type inference expected type mismatch
+    val set2  = hashSetOf(b, c) //Set<MyClass<out Any>> is inferred
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2741.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2741.fir.kt
new file mode 100644
index 00000000000..f08cf948b9b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2741.fir.kt
@@ -0,0 +1,11 @@
+//KT-2741 Compiler can't infer a type of a function literal parameter when its body contains errors
+package a
+
+fun <T, R: Comparable<R>> Iterable<T>._sortBy(f: (T) -> R): List<T> = throw Exception()
+fun <T> _arrayList(vararg values: T) : List<T> = throw Exception()
+
+class _Pair<A>(val a: A)
+
+fun test() {
+    _arrayList(_Pair(1))._sortBy { it -> <!UNRESOLVED_REFERENCE!>xxx<!> }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2754.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2754.fir.kt
new file mode 100644
index 00000000000..3fb056c4e15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2754.fir.kt
@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// T is the immutable type
+interface Builder<out T> {
+    fun build(): T
+}
+
+// T is the immutable type, U is the builder
+interface Copyable<out T, out U : Builder<T>> {
+    fun builder(): U
+}
+
+fun <T : Copyable<T, U>, U : Builder<T>> T.copy(fn: U.() -> Unit): T = throw Exception()
+
+open class Foo(val x: Int, val y: Int) : Copyable<Foo, Foo.FooBuilder> {
+    override fun builder(): FooBuilder = FooBuilder(x, y)
+
+    open class FooBuilder(var x: Int, var y: Int): Builder<Foo> {
+        override fun build(): Foo = Foo(x, y)
+    }
+}
+
+fun test() {
+    val foo1 = Foo(x = 1, y = 2)
+    val foo2 = foo1.copy { y = 3 } // this doesn't work
+    foo2 checkType { <!UNRESOLVED_REFERENCE!>_<!><Foo>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2838.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2838.fir.kt
new file mode 100644
index 00000000000..8d580c9bef0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2838.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+//KT-2838 Type inference failed on passing null as a nullable argument
+package a
+
+fun <T> foo(a: T, b: Map<T, String>?) = b?.get(a)
+fun <T> bar(a: T, b: Map<T, String>) = b.get(a)
+
+fun test(a: Int) {
+    foo(a, null)
+    bar(a, null)
+}
+fun test1(a: Int) {
+    foo(a, throw Exception())
+}
+
+fun test2(a: Int) {
+    bar(a, throw Exception())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2841.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2841.fir.kt
new file mode 100644
index 00000000000..1864a243328
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2841.fir.kt
@@ -0,0 +1,15 @@
+package a
+
+interface Closeable {}
+class C : Closeable {}
+
+public inline fun <T: Closeable, R> T.use1(block: (T)-> R) : R {
+    return block(this)
+}
+
+fun main() {
+    C().use1 {
+        w ->  // ERROR here
+        <!UNRESOLVED_REFERENCE!>x<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2841_it.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2841_it.fir.kt
new file mode 100644
index 00000000000..71a2754783b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2841_it.fir.kt
@@ -0,0 +1,18 @@
+package a
+
+interface Closeable {
+    fun close() {}
+}
+
+class C : Closeable
+
+public inline fun <T: Closeable, R> T.use(block: (t: T)-> R) : R {
+    return block(this)
+}
+
+fun test() {
+    C().use {
+        it.close()
+        <!UNRESOLVED_REFERENCE!>x<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2841_it_this.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2841_it_this.fir.kt
new file mode 100644
index 00000000000..b245c6ccfb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2841_it_this.fir.kt
@@ -0,0 +1,19 @@
+package a
+
+interface Closeable {
+    fun close() {}
+}
+
+class C : Closeable
+
+public inline fun <T: Closeable, R> use(t: T, block: T.(T)-> R) : R {
+    return t.<!UNRESOLVED_REFERENCE!>block<!>(t)
+}
+
+fun test() {
+    use(C()) {
+        this.close()
+        it.close()
+        <!UNRESOLVED_REFERENCE!>xx<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2841_this.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2841_this.fir.kt
new file mode 100644
index 00000000000..166765b55a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2841_this.fir.kt
@@ -0,0 +1,18 @@
+package a
+
+interface Closeable {
+    fun close() {}
+}
+
+class C : Closeable
+
+public inline fun <T: Closeable, R> T.use(block: T.()-> R) : R {
+    return this.<!UNRESOLVED_REFERENCE!>block<!>()
+}
+
+fun test() {
+    C().use {
+        this.close()
+        <!UNRESOLVED_REFERENCE!>x<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2842.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2842.fir.kt
new file mode 100644
index 00000000000..958e980bed9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2842.fir.kt
@@ -0,0 +1,27 @@
+package c
+
+interface A<T>
+
+fun test(a: A<Int>?) {
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>() //no error
+}
+
+fun <R> A<R>.foo() {}
+
+//------------
+fun test(nullabilityInfoMap: Map<Int, Any>?) {
+    nullabilityInfoMap.<!INAPPLICABLE_CANDIDATE!>iterator<!>() //no error
+}
+
+//resolves to
+public fun <K,V> Map<K,V>.iterator(): Iterator<Map.Entry<K,V>> {}
+
+
+//-------------
+fun foo() : Boolean {
+    val nullableList = getNullableList()
+    return nullableList.<!INAPPLICABLE_CANDIDATE!>contains<!>("")
+
+}
+
+fun getNullableList(): List<String>? = null
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt2883.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt2883.fir.kt
new file mode 100644
index 00000000000..6e9756905d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt2883.fir.kt
@@ -0,0 +1,33 @@
+// !WITH_NEW_INFERENCE
+//KT-2883 Type inference fails due to non-Unit value returned
+package a
+
+public fun doAction(action : () -> Unit){
+}
+
+class Y<TItem>(val itemToString: (TItem) -> String){
+}
+
+fun <TItem> bar(context : Y<TItem>) : TItem{
+}
+
+fun foo(){
+    val stringToString : (String) -> String = { it }
+    doAction({bar(Y<String>(stringToString))})
+}
+
+fun <T> bar(t: T): T = t
+
+fun test() {
+    
+    doAction { bar(12) }
+
+    val u: Unit =  bar(11)
+}
+
+fun testWithoutInference(col: MutableCollection<Int>) {
+    
+    doAction { col.add(2) }
+    
+    val u: Unit = col.add(2)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3007.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3007.fir.kt
new file mode 100644
index 00000000000..495431f6f60
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3007.fir.kt
@@ -0,0 +1,43 @@
+//KT-3007 Kotlin plugin 0.4.126 does not compile KAnnotator revision ba0a93eb
+package a
+
+enum class SomeEnum {
+    FIRST,
+    SECOND
+}
+
+// Doesn't work
+fun Iterable<Int>.some() {
+    this.fold(SomeEnum.FIRST, {res : SomeEnum, value ->
+        if (res == SomeEnum.FIRST) SomeEnum.FIRST else SomeEnum.SECOND
+    })
+}
+
+fun tempFun() : SomeEnum {
+    return SomeEnum.FIRST
+}
+
+// Doesn't work
+fun Iterable<Int>.someSimpleWithFun() {
+    this.fold(SomeEnum.FIRST, {res : SomeEnum, value ->
+        tempFun()
+    })
+}
+
+
+// Works
+fun Iterable<Int>.someSimple() {
+    this.fold(SomeEnum.FIRST, {res : SomeEnum, value ->
+        SomeEnum.FIRST
+    })
+}
+
+// Works
+fun Iterable<Int>.someInt() {
+    this.fold(0, {res : Int, value ->
+        if (res == 0) 1 else 0
+    })
+}
+
+//from standard library
+fun <T,R> Iterable<T>.fold(initial: R, operation: (R, T) -> R): R {}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3038.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3038.fir.kt
new file mode 100644
index 00000000000..dc958bd113c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3038.fir.kt
@@ -0,0 +1,22 @@
+//KT-3038 Wrong type inference for enum entry
+package a
+
+enum class TestEnum {
+    FIRST,
+    SECOND
+}
+
+fun <T> inferenceTest(a: T) : T = a
+
+fun hello() {
+    var enumElemFirst = inferenceTest(TestEnum.FIRST)
+    enumElemFirst = TestEnum.SECOND // Type mismatch: inferred type is testDebug.TestEnum.<class-object-for-TestEnum>.SECOND but testDebug.TestEnum.<class-object-for-TestEnum>.FIRST was expected
+
+    var enumElemSecond : TestEnum = inferenceTest(TestEnum.FIRST)
+    enumElemSecond = TestEnum.SECOND // Ok
+
+    use(enumElemFirst, enumElemSecond)
+}
+
+
+fun use(vararg a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3150.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3150.fir.kt
new file mode 100644
index 00000000000..64ae0ce8d10
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3150.fir.kt
@@ -0,0 +1,24 @@
+package aa
+
+class Some<T>
+
+class SomeTemplate {
+    fun <T> query(some: Class<T>) = some
+
+
+    // Uncomment this to get CANNOT_COMPLETE_RESOLVE error
+    fun <T> query1(some: Class<T>) = some
+    fun <T> query1(some: Some<T>) = some
+}
+
+fun SomeTemplate.query(f: (i: Int) -> Unit) = f
+fun SomeTemplate.query1(f: (i: Int) -> Unit) = f
+
+fun test() {
+    val mapperFunction = { i: Int -> }
+    SomeTemplate().query(mapperFunction)
+
+    // TYPE_MISMATCH: Required Class<[ERROR: CANT_INFER]>, Found (kotlin.Int) -> Unit
+    SomeTemplate().query { i: Int -> }
+    SomeTemplate().query1 { i: Int -> }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3174.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3174.fir.kt
new file mode 100644
index 00000000000..48bb892a997
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3174.fir.kt
@@ -0,0 +1,12 @@
+//KT-3174 Call resolver doesn't understand type is not-nullable after ?. safe call
+package a
+
+fun <T: Any> T.test(): T = this
+fun foo(a: Any?) = a?.test() // Error
+
+fun <T> T.fff(l: MutableList<T>) = l.add(this)
+
+fun test(s: String?, l: MutableList<String>) {
+    s?.fff(l)
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt32862_both.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt32862_both.fir.kt
new file mode 100644
index 00000000000..5f41403ca68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt32862_both.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+interface G<T> {
+    fun build(): G<T>
+}
+class V1<V>(val value: V)
+class V2<V>(val value: V)
+fun <V, T : V?> G<T>.foo(vararg values: V1<V>) = build()
+fun <V, T : V?> G<T>.foo(vararg values: V2<V?>) = build()
+
+fun forReference(ref: Any?) {}
+
+fun test() {
+    forReference(<!UNRESOLVED_REFERENCE!>G<Int?>::foo<!>)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt32862_none.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt32862_none.fir.kt
new file mode 100644
index 00000000000..1a40bd0ff89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt32862_none.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+fun foo(s: String) {}
+fun foo(i: Long) {}
+
+fun bar(f: (Boolean) -> Unit) {}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(<!UNRESOLVED_REFERENCE!>::foo<!>)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3301.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3301.fir.kt
new file mode 100644
index 00000000000..2f2ba646a29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3301.fir.kt
@@ -0,0 +1,20 @@
+//KT-3301 Inference with several supertypes fails
+
+package arrays
+
+interface A
+interface B
+
+object CAB : A, B
+object DAB : A, B
+
+fun m(args : Array<A>) {
+
+}
+
+fun test122() {
+    m(array(CAB, DAB)) // Wrong error here: Array<Any> is inferred while expected Array<A> is satisfied
+}
+
+//from library
+fun <T> array(vararg t: T): Array<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3344.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3344.fir.kt
new file mode 100644
index 00000000000..5202a4dcf65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3344.fir.kt
@@ -0,0 +1,16 @@
+//KT-3344 InternalError in compiler when type arguments are not specified
+
+package i
+
+import java.util.HashMap
+import java.util.ArrayList
+
+class Foo(val attributes: Map<String, String>)
+
+class Bar {
+    val foos = ArrayList<Foo>()
+
+    fun bar11(foo: Foo) {
+        foos.add(Foo(HashMap(foo.attributes))) // foo.attributes is unresolved but not marked
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt34029.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt34029.fir.kt
new file mode 100644
index 00000000000..98284406d5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt34029.fir.kt
@@ -0,0 +1,6 @@
+open class MyClass<T> {
+    object MyObject : MyClass<Boolean>() { }
+}
+
+val foo1 = MyClass.MyObject // it's ok
+val foo2 = MyClass<Boolean>.MyObject // here's stofl
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt34282.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt34282.fir.kt
new file mode 100644
index 00000000000..3697a669688
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt34282.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun bar(y: (Int) -> Int) = 1
+fun foo(x: Float) = 10f
+fun foo(x: String) = ""
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(<!UNRESOLVED_REFERENCE!>::foo<!>) // no report about unresolved callable reference for `foo`
+}
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3496.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3496.fir.kt
new file mode 100644
index 00000000000..9468733e750
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3496.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// KT-3496 Type inference bug on y[""]
+
+class B<T> {
+    fun <S> x (y: B<Iterable<S>>) {
+        val z: S = y[""] // does not work with [], but works with .get()
+    }
+    operator fun <S> get(s : String): S = throw Exception()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3496_2.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3496_2.fir.kt
new file mode 100644
index 00000000000..1fc2f31cf73
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3496_2.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+import java.util.ArrayList
+
+class F<T> {
+    fun <T, V> x (y: F<ArrayList<T>>, w: ArrayList<V>) {
+        val z: ArrayList<T> = y["", w]
+    }
+}
+operator fun <V, T> Any.get(s: String, w: ArrayList<V>): ArrayList<T> = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3559.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3559.fir.kt
new file mode 100644
index 00000000000..c1bf2ddfa18
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3559.fir.kt
@@ -0,0 +1,10 @@
+// KT-3559 Strange inference failure error message
+
+public inline fun <T:Any, R> let(subj: T?, body: (T) -> R): R? {
+    return if (subj != null) body(subj) else null
+}
+
+
+fun test(s: String?): String? {
+    return let(s) {s} // Reports: "Inference failed. Expected jet.String? but found jet.String?"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt4420.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt4420.fir.kt
new file mode 100644
index 00000000000..8952e6ff724
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt4420.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+//KT-4420 Type inference with type projections
+
+class Foo<T>
+fun <T> Foo<T>.bar(): T = throw Exception()
+
+fun main() {
+    val f: Foo<out String> = Foo()
+    f.bar() checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt702.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt702.fir.kt
new file mode 100644
index 00000000000..8cd37411b95
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt702.fir.kt
@@ -0,0 +1,20 @@
+//KT-702 Type inference failed
+package a
+//+JDK
+
+fun <T> getJavaClass() : java.lang.Class<T> { }
+
+public class Throwables() {
+    companion object {
+        public fun <X : Throwable?> propagateIfInstanceOf(throwable : Throwable?, declaredType : Class<X?>?) : Unit {
+            if (((throwable != null) && declaredType?.isInstance(throwable)!!))
+            {
+                throw declaredType?.cast(throwable)!!
+            }
+        }
+        public fun propagateIfPossible(throwable : Throwable?) : Unit {
+            <!INAPPLICABLE_CANDIDATE!>propagateIfInstanceOf<!>(throwable, getJavaClass<Error?>()) // Type inference failed: Mismatch while expanding constraints
+            <!INAPPLICABLE_CANDIDATE!>propagateIfInstanceOf<!>(throwable, getJavaClass<RuntimeException?>()) // Type inference failed: Mismatch while expanding constraints
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt731.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt731.fir.kt
new file mode 100644
index 00000000000..566f5cef041
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt731.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+//KT-731 Missing error from type inference
+package a
+
+class A<T>(x: T) {
+    val p = x
+}
+
+fun <T, G> A<T>.foo(x: (T)-> G): G {
+    return x(this.p)
+}
+
+fun main() {
+    val a = A(1)
+    val t: String = a.foo({p -> p})
+    checkSubtype<String>(t)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt742.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt742.fir.kt
new file mode 100644
index 00000000000..2fedc1e6b87
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt742.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+//KT-742 Stack overflow in type inference
+package a
+
+fun <T : Any> T?.sure() : T = this!!
+
+class List<T>(val head: T, val tail: List<T>? = null)
+
+fun <T, Q> List<T>.map1(f: (T)-> Q): List<T>? = tail!!.map1(f)
+
+fun <T, Q> List<T>.map2(f: (T)-> Q): List<T>? = tail.sure().map2(f)
+
+fun <T, Q> List<T>.map3(f: (T)-> Q): List<T>? = tail.<!INAPPLICABLE_CANDIDATE!>sure<!><T>().map3(f)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt8132.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt8132.fir.kt
new file mode 100644
index 00000000000..6304e603450
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt8132.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+// KT-8132 Can't omit lambda parameter types
+
+fun <T> test(foo: List<T>): T {
+    return if (true)
+        throw IllegalStateException()
+    else
+        foo.reduce { left, right -> left } // error: inferred type T is not subtype Nothing
+}
+
+fun <S, T: S> Iterable<T>.reduce(operation: (S, T) -> S): S = throw Exception()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt832.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt832.fir.kt
new file mode 100644
index 00000000000..d7f6d23d92a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt832.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+//KT-832 Provide better diagnostics when type inference fails for an expression that returns a function
+package a
+
+fun <T> fooT2() : (t : T) -> T {
+    return {it}
+}
+
+fun test() {
+    fooT2()(1) // here 1 should not be marked with an error
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt943.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt943.fir.kt
new file mode 100644
index 00000000000..6d899167b02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt943.fir.kt
@@ -0,0 +1,22 @@
+// !CHECK_TYPE
+
+//KT-943 Type inference failed
+package maze
+
+//+JDK
+import java.util.Collections.*
+import java.util.*
+
+fun foo(lines: List<String>) {
+    val w = max(lines, comparator {o1, o2 ->
+        val l1 : Int = o1.length // Types of o1 and o2 are ERROR
+        val l2 = o2.length
+        l1 - l2
+    }).sure()
+    checkSubtype<String>(w)
+}
+
+//standard library
+fun <T : Any> T?.sure() : T = this!!
+
+public inline fun <T> comparator(fn: (T,T) -> Int): Comparator<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt9461.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt9461.fir.kt
new file mode 100644
index 00000000000..67c205e8bbe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt9461.fir.kt
@@ -0,0 +1,17 @@
+interface In<in I>
+
+interface B : In<B>
+
+interface C<I, T>
+
+fun <I, T> In<I>.foo(f: () -> C<I, T>) {}
+fun <I, T, Self: In<I>> Self.foo2(f: () -> C<I, T>) {}
+
+class E : B // e <: In<B> <: In<E>
+
+fun test(c: C<E, Int>, e: E) {
+    e.foo<E, Int> { c }
+    e.foo { c } // error here: expected C<B, ???> but must be C<??? : B, ???>
+    e.foo2 { c }
+    e.foo2 ({ c })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt948.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt948.fir.kt
new file mode 100644
index 00000000000..8d783455714
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt948.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+//KT-948 Make type inference work with sure()/!!
+
+package a
+
+import java.util.*
+
+fun <T> emptyList() : List<T>? = ArrayList<T>()
+
+fun foo() {
+    // type arguments shouldn't be required
+    val l : List<Int> = emptyList()!!
+    val l1 = emptyList()!!
+
+    checkSubtype<List<Int>>(emptyList()!!)
+    checkSubtype<List<Int>?>(emptyList())
+
+    doWithList(emptyList()!!)
+}
+
+fun doWithList(list: List<Int>) = list
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/noRecursionOnCallingPureKotlinFunctionAsSyntheticJavaAccessor.fir.kt b/compiler/testData/diagnostics/tests/inference/regressions/noRecursionOnCallingPureKotlinFunctionAsSyntheticJavaAccessor.fir.kt
new file mode 100644
index 00000000000..ffd7499b218
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/regressions/noRecursionOnCallingPureKotlinFunctionAsSyntheticJavaAccessor.fir.kt
@@ -0,0 +1,3 @@
+class B {
+    fun getA() = a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportAboutUnresolvedReferenceAsUnresolved.fir.kt b/compiler/testData/diagnostics/tests/inference/reportAboutUnresolvedReferenceAsUnresolved.fir.kt
new file mode 100644
index 00000000000..c54efbeda12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportAboutUnresolvedReferenceAsUnresolved.fir.kt
@@ -0,0 +1,7 @@
+fun <T, U> T.map(f: (T) -> U) = f(this)
+
+fun consume(s: String) {}
+
+fun test() {
+    consume(1.<!INAPPLICABLE_CANDIDATE!>map<!>(::foo))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/ErrorTypeAsGenericParameter.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/ErrorTypeAsGenericParameter.fir.kt
new file mode 100644
index 00000000000..297a148019c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/ErrorTypeAsGenericParameter.fir.kt
@@ -0,0 +1,9 @@
+package a
+
+fun <T, R, S> foo(block: (T)-> R, second: (T)-> S) = block
+
+fun main() {
+    val fff = { x: Int -> <!UNRESOLVED_REFERENCE!>aaa<!> }
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(fff, { x -> x + 1 })
+}
+
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/FunctionPlaceholder.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/FunctionPlaceholder.fir.kt
new file mode 100644
index 00000000000..b2ae4f1fe28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/FunctionPlaceholder.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+//For testing error messages text see DiagnosticMessageTest.testFunctionPlaceholder
+package a
+
+class A<T, R>
+fun <T, R> foo(a: A<T, R>) = a
+fun <T, R> bar(f: (T) -> R) = f
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!> { <!UNRESOLVED_REFERENCE!>it<!> }
+    <!INAPPLICABLE_CANDIDATE!>foo<!> { x -> x}
+    <!INAPPLICABLE_CANDIDATE!>foo<!> { x: Int -> x}
+
+    bar { it <!UNRESOLVED_REFERENCE!>+<!> 1 }
+    bar { x -> x <!UNRESOLVED_REFERENCE!>+<!> 1}
+    bar { x: Int -> x + 1}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/NoAmbiguityForDifferentFunctionTypes.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/NoAmbiguityForDifferentFunctionTypes.fir.kt
new file mode 100644
index 00000000000..1a875004b90
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/NoAmbiguityForDifferentFunctionTypes.fir.kt
@@ -0,0 +1,16 @@
+package a
+
+interface Closeable {}
+class C : Closeable {}
+
+fun <T: Closeable, R> T.foo(block: (T)-> R) = block
+
+fun <T: Closeable, R> T.foo(block: (T, T)-> R) = block
+
+fun main() {
+    C().foo { // no ambiguity here
+        www ->
+        <!UNRESOLVED_REFERENCE!>xs<!>
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/cannotInferParameterTypeWithInference.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/cannotInferParameterTypeWithInference.fir.kt
new file mode 100644
index 00000000000..2196201049b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/cannotInferParameterTypeWithInference.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+package aa
+
+fun <T, R> foo(block: (T)-> R) = block
+
+fun test1() {
+    foo {
+        x ->  // here we have 'cannot infer parameter type' error
+        43
+    }
+}
+
+fun bar(f: (A)->Unit) {}
+
+fun test2() {
+    bar { a -> } // here we don't have 'cannot infer parameter type' error
+}
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/inferTypeFromUnresolvedArgument.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/inferTypeFromUnresolvedArgument.fir.kt
new file mode 100644
index 00000000000..14ef9857089
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/inferTypeFromUnresolvedArgument.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <K> id2(x: K, s: String): K = x
+fun <K> ret(s: String): K = TODO()
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>id2<!>(<!UNRESOLVED_REFERENCE!>unresolved<!>, "foo")
+    <!INAPPLICABLE_CANDIDATE!>id2<!>(<!UNRESOLVED_REFERENCE!>unresolved<!>, 42)
+
+    ret("foo")
+    <!INAPPLICABLE_CANDIDATE!>ret<!>(42)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/reportUnresolvedReferenceWrongReceiverForManyCandidates.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/reportUnresolvedReferenceWrongReceiverForManyCandidates.fir.kt
new file mode 100644
index 00000000000..15f474ac9b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/reportUnresolvedReferenceWrongReceiverForManyCandidates.fir.kt
@@ -0,0 +1,8 @@
+fun test() {
+    val a = <!INAPPLICABLE_CANDIDATE!>-<!>false
+}
+
+operator fun A.unaryMinus() {}
+operator fun B.unaryMinus() {}
+class A
+class B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/subtypeForInvariantWithErrorGenerics.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/subtypeForInvariantWithErrorGenerics.fir.kt
new file mode 100644
index 00000000000..984f1fee42b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/subtypeForInvariantWithErrorGenerics.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+package a
+
+fun <R> foo (f: ()->R, r: MutableList<R>) = r.add(f())
+fun <R> bar (r: MutableList<R>, f: ()->R) = r.add(f())
+
+fun test() {
+    val a = foo({1}, arrayListOf("")) //no type inference error on 'arrayListOf'
+    val b = bar(arrayListOf(""), {1})
+}
+
+// from standard library
+fun <T> arrayListOf(vararg values: T) : MutableList<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/typeInferenceFailedOnComponentN.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/typeInferenceFailedOnComponentN.fir.kt
new file mode 100644
index 00000000000..2a4bbf399ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/typeInferenceFailedOnComponentN.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+class X
+
+operator fun <T> X.component1(): T = TODO()
+
+fun test() {
+    val (y) = X()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/typeInferenceFailedOnIteratorCall.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/typeInferenceFailedOnIteratorCall.fir.kt
new file mode 100644
index 00000000000..065818b1da8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/typeInferenceFailedOnIteratorCall.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+class X
+
+operator fun <T> X.iterator(): Iterable<T> = TODO()
+
+fun test() {
+    <!UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (i in X()) {
+    }<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/wrongArgumentExtensionFunction.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/wrongArgumentExtensionFunction.fir.kt
new file mode 100644
index 00000000000..5b3f5b533e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/wrongArgumentExtensionFunction.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A
+fun A.fn(b: Int): Nothing = TODO()
+
+fun A.run() {
+    "".apply { <!INAPPLICABLE_CANDIDATE!>fn<!>("") }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/reportingImprovements/wrongArgumentPassedToLocalExtensionFunction.fir.kt b/compiler/testData/diagnostics/tests/inference/reportingImprovements/wrongArgumentPassedToLocalExtensionFunction.fir.kt
new file mode 100644
index 00000000000..3a3c8c81dea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/reportingImprovements/wrongArgumentPassedToLocalExtensionFunction.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// WITH_RUNTIME
+
+fun Runnable.test(f: Runnable.(Int) -> Unit) {
+    <!INAPPLICABLE_CANDIDATE!>f<!>("")
+}
+
+fun test(f: Runnable.(Int) -> Unit, runnable: Runnable) {
+    with (runnable) {
+        <!INAPPLICABLE_CANDIDATE!>f<!>("")
+    }
+}
+
+fun Int.test(f: String.(Int) -> Unit) {
+    f("", 0)
+    <!INAPPLICABLE_CANDIDATE!>f<!>("")
+    with("") {
+        <!INAPPLICABLE_CANDIDATE!>f<!>(0)
+        <!INAPPLICABLE_CANDIDATE!>f<!>(0.0)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/substitutions/delegationAndInference.fir.kt b/compiler/testData/diagnostics/tests/inference/substitutions/delegationAndInference.fir.kt
new file mode 100644
index 00000000000..bac19086767
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/substitutions/delegationAndInference.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.KProperty
+
+class A(val map: MutableMap<String, CharSequence>) {
+
+    var a: String by map.withDefault1 { "foo" }
+}
+
+operator fun <G> MutableMap<in String, in G>.getValue(thisRef: Any?, property: KProperty<*>): G = throw Exception()
+
+operator fun <S> MutableMap<in String, in S>.setValue(thisRef: Any?, property: KProperty<*>, value: S) {}
+
+fun <K, V> MutableMap<K, V>.withDefault1(default: (key: K) -> V): MutableMap<K, V> = this
diff --git a/compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitution.fir.kt b/compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitution.fir.kt
new file mode 100644
index 00000000000..18c5e2a05e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitution.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+class B {
+    class Builder
+}
+
+typealias ApplyRestrictions = B.Builder.() -> B.Builder
+
+fun applyRestrictions1(): ApplyRestrictions = TODO()
+fun applyRestrictions2() = applyRestrictions1()
+fun <K> applyRestrictions3(e: K) = applyRestrictions1()
+
+fun buildB() {
+    val a1 = applyRestrictions1()
+    val a2 = applyRestrictions2()
+    val a3 = applyRestrictions3("foo")
+
+    B.Builder().<!UNRESOLVED_REFERENCE!>a1<!>()
+    B.Builder().<!UNRESOLVED_REFERENCE!>a2<!>()
+    B.Builder().<!UNRESOLVED_REFERENCE!>a3<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitutionOldInference.fir.kt b/compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitutionOldInference.fir.kt
new file mode 100644
index 00000000000..cf0a40467b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/substitutions/kt32189returnTypeWithTypealiasSubtitutionOldInference.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: -NewInference
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+class B {
+    class Builder
+}
+
+typealias ApplyRestrictions = B.Builder.() -> B.Builder
+
+fun applyRestrictions1(): ApplyRestrictions = TODO()
+fun applyRestrictions2() = applyRestrictions1()
+fun <K> applyRestrictions3(e: K) = applyRestrictions1()
+
+fun buildB() {
+    val a1 = applyRestrictions1()
+    val a2 = applyRestrictions2()
+    val a3 = applyRestrictions3("foo")
+
+    B.Builder().<!UNRESOLVED_REFERENCE!>a1<!>()
+    B.Builder().<!UNRESOLVED_REFERENCE!>a2<!>()
+    B.Builder().<!UNRESOLVED_REFERENCE!>a3<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/inference/substitutions/kt6081SubstituteIntoClassCorrectly.fir.kt b/compiler/testData/diagnostics/tests/inference/substitutions/kt6081SubstituteIntoClassCorrectly.fir.kt
new file mode 100644
index 00000000000..e8976cb2bbd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/substitutions/kt6081SubstituteIntoClassCorrectly.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+//KT-6081 Chained generic method calls: wrong type inference
+
+class Bar<T>
+
+fun <T> bar(): Bar<T> = null!!
+
+class Foo {
+    fun <R> add(bar: Bar<R>): Foo {return this}
+}
+
+fun doesNotWork(bi: Bar<Int>, bs: Bar<String>) {
+    Foo().add(bi).add(bs)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/substitutions/simpleSubstitutionCheckTypeArgumentsNotTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/inference/substitutions/simpleSubstitutionCheckTypeArgumentsNotTypeParameters.fir.kt
new file mode 100644
index 00000000000..5f9f2718b55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/substitutions/simpleSubstitutionCheckTypeArgumentsNotTypeParameters.fir.kt
@@ -0,0 +1,10 @@
+class A<T> {
+    fun useT(t: T) = t
+
+    fun <U> newA(): A<U> = A()
+}
+
+fun test1() {
+    A<Int>().newA<String>().useT("")
+    A<Int>().newA<String>().<!INAPPLICABLE_CANDIDATE!>useT<!>(1)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/substitutions/substitutionIntoAnonymousClass.fir.kt b/compiler/testData/diagnostics/tests/inference/substitutions/substitutionIntoAnonymousClass.fir.kt
new file mode 100644
index 00000000000..718e458fe96
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/substitutions/substitutionIntoAnonymousClass.fir.kt
@@ -0,0 +1,25 @@
+class Test {
+    private fun <T : Any> T.self() = object {
+        fun bar(): T {
+            return this@self
+        }
+    }
+    fun test() {
+        1.self().bar() <!INAPPLICABLE_CANDIDATE!>+<!> 1
+    }
+}
+
+class Foo<R> {
+    private fun <T> bar() = object {
+        fun baz(): Foo<R> {
+            return this@Foo
+        }
+    }
+
+    fun getR(r: R) = r
+
+    fun test() {
+        Foo<Int>().bar<String>().baz().getR(1)
+        Foo<Int>().bar<String>().baz().<!INAPPLICABLE_CANDIDATE!>getR<!>("")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/substitutions/substitutionIntoInnerClass.fir.kt b/compiler/testData/diagnostics/tests/inference/substitutions/substitutionIntoInnerClass.fir.kt
new file mode 100644
index 00000000000..394619704fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/substitutions/substitutionIntoInnerClass.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Outer<T> {
+    inner class Inner<I> {
+        fun getOuter(): Outer<T> = this@Outer
+        fun <R> genericFun(r: R): Outer<T> = this@Outer
+    }
+    fun useOuterParam(t: T) {}
+}
+
+fun test1() {
+    Outer<Int>().Inner<String>().getOuter().useOuterParam(22)
+    Outer<Int>().Inner<String>().getOuter().<!INAPPLICABLE_CANDIDATE!>useOuterParam<!>("")
+}
+
+
+class A
+class B
+
+fun test1(a: A, b: B) {
+    Outer<Int>().Inner<String>().genericFun(a).Inner<Double>().genericFun(b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/tryNumberLowerBoundsBeforeUpperBounds.fir.kt b/compiler/testData/diagnostics/tests/inference/tryNumberLowerBoundsBeforeUpperBounds.fir.kt
new file mode 100644
index 00000000000..0254636798a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/tryNumberLowerBoundsBeforeUpperBounds.fir.kt
@@ -0,0 +1,6 @@
+public fun <T: Any> iterate(initialValue: T, nextFunction: (T) -> T?): Iterator<T> =
+        throw Exception("$initialValue $nextFunction")
+
+fun foo() {
+    iterate(3) { n -> if (n > 0) n - 1 else null }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/typeConstructorMismatch.fir.kt b/compiler/testData/diagnostics/tests/inference/typeConstructorMismatch.fir.kt
new file mode 100644
index 00000000000..d6f97330e59
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/typeConstructorMismatch.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+package typeConstructorMismatch
+//+JDK
+
+import java.util.*
+
+fun test(set: Set<String>) {
+    <!INAPPLICABLE_CANDIDATE!>elemAndList<!>("2", set)
+
+    "".<!INAPPLICABLE_CANDIDATE!>elemAndListWithReceiver<!>("", set)
+}
+
+fun <R> elemAndList(r: R, t: List<R>): R = r
+fun <R> R.elemAndListWithReceiver(r: R, t: List<R>): R = r
diff --git a/compiler/testData/diagnostics/tests/inference/typeInferenceExpectedTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/inference/typeInferenceExpectedTypeMismatch.fir.kt
new file mode 100644
index 00000000000..e620f3720a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/typeInferenceExpectedTypeMismatch.fir.kt
@@ -0,0 +1,42 @@
+// !WITH_NEW_INFERENCE
+package typeInferenceExpectedTypeMismatch
+
+import java.util.*
+
+fun test() {
+    val s : Set<Int> = newList()
+    use(s)
+}
+
+fun <S> newList() : ArrayList<S> {
+    return ArrayList<S>()
+}
+
+interface Out<out T>
+interface In<in T>
+
+interface Two<T, R>
+
+interface A
+interface B: A
+interface C: A
+
+fun <T, R> foo(o: Out<T>, i: In<R>): Two<T, R> = throw Exception("$o $i")
+
+fun test1(outA: Out<A>, inB: In<B>) {
+    foo(outA, inB)
+
+    val b: Two<A, C> = foo(outA, inB)
+    use(b)
+}
+
+fun <T> bar(o: Out<T>, i: In<T>): Two<T, T> = throw Exception("$o $i")
+
+fun test2(outA: Out<A>, inC: In<C>) {
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(outA, inC)
+
+    val b: Two<A, B> = <!INAPPLICABLE_CANDIDATE!>bar<!>(outA, inC)
+    use(b)
+}
+
+fun use(vararg a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/typeParameterInConstructor.fir.kt b/compiler/testData/diagnostics/tests/inference/typeParameterInConstructor.fir.kt
new file mode 100644
index 00000000000..d6aa122b339
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/typeParameterInConstructor.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: +NewInference
+
+class B<O>(val obj: O) {
+    val v = B(obj)
+}
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/conflictingSubstitutionsFromUpperBound.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/conflictingSubstitutionsFromUpperBound.fir.kt
new file mode 100644
index 00000000000..5f534de1211
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/conflictingSubstitutionsFromUpperBound.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+
+package g
+
+import java.util.HashSet
+fun <T, C: Collection<T>> convert(src: Collection<T>, dest: C): C = throw Exception("$src $dest")
+
+fun test(l: List<Int>) {
+    //todo should be inferred
+    val r = convert(l, HashSet())
+    r checkType { <!UNRESOLVED_REFERENCE!>_<!><HashSet<Int>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.fir.kt
new file mode 100644
index 00000000000..e9d910c26bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/doNotInferFromBoundsOnly.fir.kt
@@ -0,0 +1,68 @@
+// !WITH_NEW_INFERENCE
+package a
+
+interface A
+
+fun <T> emptyList(): List<T> = throw Exception()
+
+fun test1() {
+    emptyList()
+}
+
+//--------------
+
+fun <T: A> emptyListOfA(): List<T> = throw Exception()
+
+fun test2() {
+    emptyListOfA()
+}
+
+//--------------
+
+fun <T: A, R: T> emptyStrangeMap(): Map<T, R> = throw Exception()
+
+fun test3() {
+    emptyStrangeMap()
+}
+
+//--------------
+
+fun <T, R: T> emptyStrangeMap1(t: T): Map<T, R> = throw Exception("$t")
+
+fun test4() {
+    emptyStrangeMap1(1)
+}
+
+//--------------
+
+fun <T: A, R> emptyStrangeMap2(t: T): Map<T, R> where R: T = throw Exception("$t")
+
+fun test5(a: A) {
+    emptyStrangeMap2(a)
+}
+
+//--------------
+
+fun <T: A, R: T> emptyStrangeMap3(r: R): Map<T, R> = throw Exception("$r")
+
+fun test6(a: A) {
+    emptyStrangeMap3(a)
+}
+
+//--------------
+
+fun <T, R: T> emptyStrangeMap4(l: MutableList<T>): Map<T, R> = throw Exception("$l")
+
+fun test7(list: MutableList<Int>) {
+    emptyStrangeMap4(list)
+}
+
+//--------------
+
+fun test7() : Map<A, A> = emptyStrangeMap()
+
+//--------------
+
+fun <U, V: U> foo(): U = throw Exception()
+
+fun test8(): Int = foo()
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/intersectUpperBounds.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/intersectUpperBounds.fir.kt
new file mode 100644
index 00000000000..3569deeff8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/intersectUpperBounds.fir.kt
@@ -0,0 +1,33 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+package s
+
+interface In<in T>
+
+interface A
+interface B
+interface C: A, B
+
+fun <T> foo(in1: In<T>, in2: In<T>): T = throw Exception("$in1 $in2")
+
+fun test(inA: In<A>, inB: In<B>, inC: In<C>) {
+
+    foo(inA, inB)
+
+    val r = foo(inA, inC)
+    checkSubtype<C>(r)
+
+    val c: C = foo(inA, inB)
+
+    use(c)
+}
+
+fun <T: C> bar(in1: In<T>): T = throw Exception("$in1")
+
+fun test(inA: In<A>) {
+    val r = bar(inA)
+    checkSubtype<C>(r)
+}
+
+fun use(vararg a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/kt2856.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/kt2856.fir.kt
new file mode 100644
index 00000000000..6688ff60d29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/kt2856.fir.kt
@@ -0,0 +1,20 @@
+//KT-2856 Fix the getOrElse signature to be able to return any supertype of V
+package d
+
+import java.util.HashMap
+
+public inline fun <K,V1, V: V1> Map<K,V>.getOrElse1(key: K, defaultValue: ()-> V1) : V1 {
+    if (this.containsKey(key)) {
+        return this.get(key) as V
+    } else {
+        return defaultValue()
+    }
+}
+
+fun main() {
+    val map = HashMap<Int, Int>()
+    println(map.getOrElse1(2, { null })) // Error
+}
+
+//from standard library
+fun println(message : Any?) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/nonNullUpperBound.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/nonNullUpperBound.fir.kt
new file mode 100644
index 00000000000..21379475c41
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/nonNullUpperBound.fir.kt
@@ -0,0 +1,13 @@
+fun <R : Any> unescape(value: Any): R? = throw Exception("$value")
+
+fun <T: Any> foo(v: Any): T? = unescape(v)
+
+//--------------
+
+interface A
+
+fun <R : A> unescapeA(value: Any): R? = throw Exception("$value")
+
+
+fun <T: A> fooA(v: Any): T? = unescapeA(v)
+
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/typeParameterAsUpperBound.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/typeParameterAsUpperBound.fir.kt
new file mode 100644
index 00000000000..a88eaaa611f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/typeParameterAsUpperBound.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+
+@kotlin.internal.InlineOnly
+public inline fun <C, R> C.ifEmpty(f: () -> R): R where C : Collection<*>, C : R = if (isEmpty()) f() else this
+
+public fun <T> listOf(t: T): List<T> = TODO()
+
+
+fun usage(c: List<String>) {
+    val cn = c.ifEmpty { null }
+    cn checkType { <!UNRESOLVED_REFERENCE!>_<!><List<String>?>() }
+
+    val cs = c.ifEmpty { listOf("x") }
+    cs checkType { <!UNRESOLVED_REFERENCE!>_<!><List<String>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/useBoundsIfUnknownParameters.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/useBoundsIfUnknownParameters.fir.kt
new file mode 100644
index 00000000000..05c1fbf9520
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/useBoundsIfUnknownParameters.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+package Hello
+
+open class Base<T>
+class StringBase : Base<String>()
+
+class Client<T, X: Base<T>>(x: X)
+
+fun test() {
+    val c = Client(StringBase()) // Type inference fails here for T.
+    val i : Int = c
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/upperBounds/useBoundsToInferTypeParamsSimple.fir.kt b/compiler/testData/diagnostics/tests/inference/upperBounds/useBoundsToInferTypeParamsSimple.fir.kt
new file mode 100644
index 00000000000..17a39c6633e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/upperBounds/useBoundsToInferTypeParamsSimple.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+package a
+
+fun <V: U, U> foo(v: V, u: U) = u
+fun <U, V: U> bar(v: V, u: U) = u
+
+fun test(a: Any, s: String) {
+    val b = foo(a, s)
+    checkItIsExactlyAny(a, arrayListOf(b))
+    val c = bar(a, s)
+    checkItIsExactlyAny(a, arrayListOf(c))
+}
+
+fun <T> checkItIsExactlyAny(t: T, l: MutableList<T>) {}
+
+fun <V : U, U> baz(v: V, u: MutableSet<U>) = u
+
+fun test(a: Any, s: MutableSet<String>) {
+    <!INAPPLICABLE_CANDIDATE!>baz<!>(a, s)
+}
+
+//from standard library
+fun <T> arrayListOf(vararg t: T): MutableList<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/useFunctionLiteralsToInferType.fir.kt b/compiler/testData/diagnostics/tests/inference/useFunctionLiteralsToInferType.fir.kt
new file mode 100644
index 00000000000..9a8a8632d35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/useFunctionLiteralsToInferType.fir.kt
@@ -0,0 +1,16 @@
+package m
+
+import java.util.HashSet
+
+// ----------------------------------
+fun <K, V> testGetOrPut(result : MutableMap<K, Set<V>>, key: K) {
+    result.getOrPut(key) { HashSet() }
+}
+
+fun <K,V> MutableMap<K,V>.getOrPut(key: K, defaultValue: ()-> V) : V = throw Exception("$key $defaultValue")
+
+// ----------------------------------
+class Property<T: Comparable<T>>(val name: String, val default: () -> T) {}
+
+fun testProperty() = Property("", { -1.toLong() })
+fun testProperty1() = Property("", { "" })
diff --git a/compiler/testData/diagnostics/tests/infos/PropertiesWithBackingFields.fir.kt b/compiler/testData/diagnostics/tests/infos/PropertiesWithBackingFields.fir.kt
new file mode 100644
index 00000000000..6e63b72af36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/infos/PropertiesWithBackingFields.fir.kt
@@ -0,0 +1,59 @@
+abstract class Test() {
+    abstract val x : Int
+    abstract val x1 : Int get
+    abstract val x2 : Int get() = 1
+
+    val a : Int
+    val b : Int get
+    val c = 1
+
+    val c1 = 1
+      get
+    val c2 : Int
+        get() = 1
+    val c3 : Int
+        get() { return 1 }
+    val c4 : Int
+        get() = 1
+    val c5 : Int
+        get() = field + 1
+
+    abstract var y : Int
+    abstract var y1 : Int get
+    abstract var y2 : Int set
+    abstract var y3 : Int set get
+    abstract var y4 : Int set get() = 1
+    abstract var y5 : Int set(x) {} get() = 1
+    abstract var y6 : Int set(x) {}
+
+    var v : Int
+    var v1 : Int get
+    var v2 : Int get set
+    var v3 : Int get() = 1; set
+    var v4 : Int get() = 1; set(x){}
+
+    var v5 : Int get() = 1; set(x){field = x}
+    var v6 : Int get() = field + 1; set(x){}
+
+  abstract val v7 : Int get
+  abstract var v8 : Int get set
+  var v9 : Int set
+  var v10 : Int  get
+  abstract val v11 : Int abstract get
+  abstract var v12 : Int abstract get abstract set
+
+}
+
+open class Super(i : Int)
+
+class TestPCParameters(w : Int, x : Int, val y : Int, var z : Int) : Super(w) {
+
+  val xx = w
+
+  init {
+    w + 1
+  }
+
+  fun foo() = <!UNRESOLVED_REFERENCE!>x<!>
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/infos/SmartCasts.fir.kt b/compiler/testData/diagnostics/tests/infos/SmartCasts.fir.kt
new file mode 100644
index 00000000000..091aaf5a166
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/infos/SmartCasts.fir.kt
@@ -0,0 +1,228 @@
+// !WITH_NEW_INFERENCE
+open class A() {
+  fun foo() {}
+}
+
+class B() : A() {
+  fun bar() {}
+}
+
+fun f9(init : A?) {
+  val a : A? = init
+  a?.foo()
+  a?.<!UNRESOLVED_REFERENCE!>bar<!>()
+  if (a is B) {
+    a.bar()
+    a.foo()
+  }
+  a?.foo()
+  a?.<!UNRESOLVED_REFERENCE!>bar<!>()
+  if (!(a is B)) {
+    a?.<!UNRESOLVED_REFERENCE!>bar<!>()
+    a?.foo()
+  }
+  if (!(a is B) || a.bar() == Unit) {
+      a?.<!UNRESOLVED_REFERENCE!>bar<!>()
+  }
+  if (!(a is B)) {
+    return;
+  }
+  a.bar()
+  a.foo()
+}
+
+fun f10(init : A?) {
+  val a : A? = init
+  if (!(a is B)) {
+    return;
+  }
+  if (!(a is B)) {
+    return;
+  }
+}
+
+class C() : A() {
+  fun bar() {
+
+  }
+}
+
+fun f101(a : A?) {
+    if (a is C) {
+      a.bar();
+    }
+}
+
+fun f11(a : A?) {
+  when (a) {
+    is B -> a.bar()
+    is A -> a.foo()
+    is Any -> a.foo()
+    is Any? -> a.<!UNRESOLVED_REFERENCE!>bar<!>()
+    else -> a?.foo()
+  }
+}
+
+fun f12(a : A?) {
+  when (a) {
+    is B -> a.bar()
+    is A -> a.foo()
+    is Any -> a.foo();
+    is Any? -> a.<!UNRESOLVED_REFERENCE!>bar<!>()
+    is C -> a.bar()
+    else -> a?.foo()
+  }
+
+  if (a is Any?) {
+    a?.<!UNRESOLVED_REFERENCE!>bar<!>()
+  }
+  if (a is B) {
+    a.foo()
+    a.bar()
+  }
+}
+
+fun f13(a : A?) {
+  if (a is B) {
+    a.foo()
+    a.bar()
+  }
+  else {
+    a?.foo()
+    <!UNRESOLVED_REFERENCE!>c<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+  }
+
+  a?.foo()
+  if (!(a is B)) {
+    a?.foo()
+    <!UNRESOLVED_REFERENCE!>c<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+  }
+  else {
+    a.foo()
+    <!UNRESOLVED_REFERENCE!>c<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+  }
+
+  a?.foo()
+  if (a is B && a.foo() == Unit) {
+    a.foo()
+    a.bar()
+  }
+  else {
+    a?.foo()
+    <!UNRESOLVED_REFERENCE!>c<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+  }
+
+  if (!(a is B) || !(a is C)) {
+  }
+  else {
+  }
+
+  if (!(a is B) || !(a is C)) {
+  }
+
+  if (!(a is B)) return
+  a.bar()
+}
+
+fun f14(a : A?) {
+  while (!(a is B)) {
+  }
+  a.<!UNRESOLVED_REFERENCE!>bar<!>()
+}
+fun f15(a : A?) {
+  do {
+  } while (!(a is B))
+  a.<!UNRESOLVED_REFERENCE!>bar<!>()
+}
+
+fun getStringLength(obj : Any) : Char? {
+  if (obj !is String)
+    return null
+  return obj.get(0) // no cast to String is needed
+}
+
+fun toInt(i: Int?): Int = if (i != null) i else 0
+fun illegalWhenBody(a: Any): Int = when(a) {
+    is Int -> a
+    is String -> a
+}
+fun illegalWhenBlock(a: Any): Int {
+    when(a) {
+        is Int -> return a
+        is String -> return a
+    }
+}
+fun declarations(a: Any?) {
+    if (a is String) {
+       val p4: String = a
+    }
+    if (a is String?) {
+        if (a != null) {
+            val s: String = a
+        }
+    }
+    if (a != null) {
+        if (a is String?) {
+            val s: String = a
+        }
+    }
+}
+fun vars(a: Any?) {
+    var b: Int = 0
+    if (a is Int) {
+        b = a
+    }
+}
+fun returnFunctionLiteralBlock(a: Any?): Function0<Int> {
+    if (a is Int) return { a }
+    else return { 1 }
+}
+fun returnFunctionLiteral(a: Any?): Function0<Int> {
+    if (a is Int) return { -> a }
+    else return { -> 1 }
+}
+
+fun returnFunctionLiteralExpressionBody(a: Any?): Function0<Int> =
+        if (a is Int) { -> a }
+        else { -> 1 }
+
+
+fun mergeSmartCasts(a: Any?) {
+  if (a is String || a is Int) {
+    a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("")
+    a.toString()
+  }
+  if (a is Int || a is String) {
+    a.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("")
+  }
+  when (a) {
+    is String, is Any -> a.<!UNRESOLVED_REFERENCE!>compareTo<!>("")
+  }
+  if (a is String && a is Any) {
+    val i: Int = a.compareTo("")
+  }
+  if (a is String && a.compareTo("") == 0) {}
+  if (a is String || a.<!UNRESOLVED_REFERENCE!>compareTo<!>("") == 0) {}
+}
+
+//mutability
+fun f(): String {
+    var a: Any = 11
+    if (a is String) {
+        // a is a string, despite of being a variable
+        val i: String = a
+        a.compareTo("f")
+        // Beginning from here a is captured in a closure but nobody modifies it
+        val f: Function0<String> = { a }
+        return a
+    }
+    return ""
+}
+
+fun foo(aa: Any?): Int {
+    var a = aa
+    if (a is Int?) {
+        return a
+    }
+    return 1
+}
diff --git a/compiler/testData/diagnostics/tests/inline/anonymousObjects.fir.kt b/compiler/testData/diagnostics/tests/inline/anonymousObjects.fir.kt
new file mode 100644
index 00000000000..af6c62677c6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/anonymousObjects.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -NON_LOCAL_RETURN_NOT_ALLOWED
+
+inline fun <R> inlineFun(p: () -> R) {
+    val s = object {
+
+        val z = p()
+
+        fun a() {
+            p()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/assignment.fir.kt b/compiler/testData/diagnostics/tests/inline/assignment.fir.kt
new file mode 100644
index 00000000000..3e04fcb9ef6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/assignment.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE
+inline fun inlineFunWithInvoke(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    var d = s
+    d = s
+
+    var e = ext
+    e = ext
+}
+
+
+inline fun Function1<Int, Unit>.inlineExt() {
+    var d = this
+    d = this
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/andOr.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/andOr.fir.kt
new file mode 100644
index 00000000000..8d7a1cd5fb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/andOr.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -TYPE_MISMATCH
+
+inline fun inlineFunWithInvoke(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    s && ext
+    s || s
+}
+
+inline fun inlineFunWithInvokeNonInline(noinline s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    s && ext
+    s || s
+}
+
+inline fun Function1<Int, Unit>.inlineExt() {
+    invoke(11)
+    this && this
+    this || this
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/arrayAccess.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/arrayAccess.fir.kt
new file mode 100644
index 00000000000..697bc552738
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/arrayAccess.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE
+operator inline fun <T, U> Function1<T, U>.get(index : Int) {
+
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U) {
+    s[1]
+}
+
+//noinline
+operator fun <T, U, V> Function2<T, U, V>.get(index : Int) {
+
+}
+
+operator fun <T, U, V, W> @ExtensionFunctionType Function3<T, U, V, W>.get(index : Int) {
+
+}
+
+inline fun <T, U, V, W> inlineFunWithInvoke(s: (p: T, l: U) -> V, ext: T.(p: U, l: V) -> W) {
+    s[1]
+    ext[1]
+}
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/assignment.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/assignment.fir.kt
new file mode 100644
index 00000000000..7ec7960bb2a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/assignment.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -NON_LOCAL_RETURN_NOT_ALLOWED
+
+operator fun <T, U> Function1<T, U>.minusAssign(p: Function1<T, U>) {}
+
+inline operator fun <T, U> Function1<T, U>.modAssign(p: Function1<T, U>) = {
+    this += p
+    p += this
+}
+
+inline operator fun <T, U> Function1<T, U>.plusAssign(p: Function1<T, U>) {
+    this -= p
+    p -= this
+}
+
+operator fun <T, U, V> @ExtensionFunctionType Function2<T, U, V>.minusAssign(ext : @ExtensionFunctionType Function2<T, U, V>) {}
+
+inline operator fun <T, U, V> @ExtensionFunctionType Function2<T, U, V>.modAssign(ext : @ExtensionFunctionType Function2<T, U, V>) = {
+    this += ext
+    ext += this
+}
+
+inline operator fun <T, U, V> @ExtensionFunctionType Function2<T, U, V>.plusAssign(ext : @ExtensionFunctionType Function2<T, U, V>) {
+    this -= ext
+    ext -= this
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U, ext: T.(p: U) -> V) {
+    s += s
+    ext += ext
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/comparison.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/comparison.fir.kt
new file mode 100644
index 00000000000..af0da08e58c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/comparison.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE
+
+inline operator fun <T, U> Function1<T, U>.compareTo(p: Function1<T, U>) = 1
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U) {
+    s < s
+    s <= s
+    s > s
+    s >= s
+}
+
+//noinline
+operator fun <T, U, V> Function2<T, U, V>.compareTo(index : Function2<T, U, V>) = 1
+operator fun <T, U, V, W> @ExtensionFunctionType Function3<T, U, V, W>.compareTo(index : @ExtensionFunctionType Function3<T, U, V, W>) = 1
+
+inline fun <T, U, V, W> inlineFunWithInvoke(s: (p: T, l: U) -> V, ext: T.(p: U, l: V) -> W) {
+    s < s
+    s <= s
+    s > s
+    s >= s
+
+    ext < ext
+    ext > ext
+    ext <= ext
+    ext >= ext
+}
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/componentAccess.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/componentAccess.fir.kt
new file mode 100644
index 00000000000..d57da8784d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/componentAccess.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE
+inline operator fun <T, U> Function1<T, U>.component1() = 1
+inline operator fun <T, U> Function1<T, U>.component2() = 2
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U) {
+    val (d1, e1) = s
+}
+
+operator fun <T, U, V> Function2<T, U, V>.component1() = 1
+operator fun <T, U, V> Function2<T, U, V>.component2() = 2
+
+operator fun <T, U, V, W> @ExtensionFunctionType Function3<T, U, V, W>.component1() = 1
+operator fun <T, U, V, W> @ExtensionFunctionType Function3<T, U, V, W>.component2() = 2
+
+inline fun <T, U, V, W> inlineFunWithInvoke(s: (p: T, l: U) -> V, ext: T.(p: U, l: V) -> W) {
+    val (d1, e1) = s
+    val (d2, e2) = ext
+}
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/contains.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/contains.fir.kt
new file mode 100644
index 00000000000..d74c5d90803
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/contains.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -RECURSION_IN_INLINE
+operator inline fun <T, U> Function1<T, U>.contains(p: Function1<T, U>): Boolean {
+    this in p
+    p in this
+    return false
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U) {
+    s in s
+    s !in s
+}
+
+
+operator fun <T, U, V> Function2<T, U, V>.contains(p: Function2<T, U, V>): Boolean = false
+
+operator fun <T, U, V, W> @ExtensionFunctionType Function3<T, U, V, W>.contains(ext: @ExtensionFunctionType Function3<T, U, V, W>): Boolean = false
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T, l: U) -> U, ext: T.(p: U, l: U) -> V) {
+    s in s
+    s !in s
+
+    ext in ext
+    ext !in ext
+}
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/mathOperations.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/mathOperations.fir.kt
new file mode 100644
index 00000000000..d641299f7b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/mathOperations.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -CONFLICTING_JVM_DECLARATIONS -CONFLICTING_OVERLOADS
+operator fun <T, U> Function1<T, U>.minus(p: Function1<T, U>) {
+
+}
+
+operator fun <T, U, V> @ExtensionFunctionType Function2<T, U, V>.minus(p: T.(p: U) -> V) {
+
+}
+
+inline operator fun <T, U> Function1<T, U>.plus(p: Function1<T, U>) {
+    this - p
+}
+
+inline operator fun <T, U, V> @ExtensionFunctionType Function2<T, U, V>.plus(p: T.(p: U) -> V) {
+    this - p
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U, ext: T.(p: U) -> V) {
+    s + s
+    ext + ext
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U, ext: T.(p: U) -> V) {
+    s + s
+    ext + ext
+}
+
+inline fun <T, U> Function1<T, U>.submit() {
+    this + this
+}
+
+inline fun <T, U, V> @ExtensionFunctionType Function2<T, U, V>.submit() {
+    this + this
+}
diff --git a/compiler/testData/diagnostics/tests/inline/binaryExpressions/rangeTo.fir.kt b/compiler/testData/diagnostics/tests/inline/binaryExpressions/rangeTo.fir.kt
new file mode 100644
index 00000000000..fca75c38907
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/binaryExpressions/rangeTo.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -RECURSION_IN_INLINE
+
+inline operator fun <T, U> Function1<T, U>.rangeTo(p: Function1<T, U>): ClosedRange<Int> {
+    this..p
+    p..this
+    return 1..2
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U) {
+    s..s
+    s..s
+}
+
+
+operator fun <T, U, V> Function2<T, U, V>.rangeTo(p: Function2<T, U, V>): ClosedRange<Int> {
+    return 1..2
+}
+
+operator fun <T, U, V, W> @ExtensionFunctionType Function3<T, U, V, W>.rangeTo(ext: @ExtensionFunctionType Function3<T, U, V, W>): ClosedRange<Int> {
+    return 1..2
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T, l: U) -> U, ext: T.(p: U, l: U) -> V) {
+    s..s
+    s..s
+
+    ext..ext
+    ext..ext
+}
diff --git a/compiler/testData/diagnostics/tests/inline/capture.fir.kt b/compiler/testData/diagnostics/tests/inline/capture.fir.kt
new file mode 100644
index 00000000000..57dbe1cc45f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/capture.fir.kt
@@ -0,0 +1,51 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -NON_LOCAL_RETURN_NOT_ALLOWED
+
+infix fun Function1<Int, Unit>.noInlineExt(p: Int) {}
+
+inline infix fun Function1<Int, Unit>.inlineExt2(p: Int) {
+    <!UNRESOLVED_REFERENCE!>{
+        noInlineExt(11)
+        this.noInlineExt(11)
+        this noInlineExt 11
+        this
+    }()<!>
+}
+
+
+inline fun Function1<Int, Unit>.inlineExt() {
+    <!UNRESOLVED_REFERENCE!>{
+        inlineExt2(1)
+        this.inlineExt2(1)
+        this inlineExt2 1
+        this(11)
+    }()<!>
+}
+
+inline fun inlineFunWithInvoke(s: (p: Int) -> Unit) {
+    <!UNRESOLVED_REFERENCE!>{
+        s(11)
+        s.invoke(11)
+        s invoke 11
+    }()<!>
+}
+
+inline fun inlineFunWithInvokeNonInline(noinline s: (p: Int) -> Unit) {
+    <!UNRESOLVED_REFERENCE!>{
+        s(11)
+        s.invoke(11)
+        s invoke 11
+    }()<!>
+}
+
+
+inline fun testExtension(s: (p: Int) -> Unit) {
+    <!UNRESOLVED_REFERENCE!>{
+        s.inlineExt()
+    } ()<!>
+}
+
+inline fun inlineFunWrongExtension(s: (p: Int) -> Unit) {
+    <!UNRESOLVED_REFERENCE!>{
+        s.noInlineExt(11)
+    } ()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/constructor.fir.kt b/compiler/testData/diagnostics/tests/inline/constructor.fir.kt
new file mode 100644
index 00000000000..288bd2417ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/constructor.fir.kt
@@ -0,0 +1,7 @@
+class Z(s: (Int) -> Int) {
+
+}
+
+public inline fun test(s : (Int) -> Int) {
+    Z(s)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/default.fir.kt b/compiler/testData/diagnostics/tests/inline/default.fir.kt
new file mode 100644
index 00000000000..6a0b5067607
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/default.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun default(s : Int = 10) {
+
+}
+
+inline fun default2(p: Int, s : String = "OK") {
+
+}
+
+open class Base {
+    inline final fun foo(a: Int = 1) {}
+
+    inline final fun foo2(a: Int = 1, s: String = "OK") {}
+}
diff --git a/compiler/testData/diagnostics/tests/inline/defaultLambdaInlineDisable.fir.kt b/compiler/testData/diagnostics/tests/inline/defaultLambdaInlineDisable.fir.kt
new file mode 100644
index 00000000000..303a77830d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/defaultLambdaInlineDisable.fir.kt
@@ -0,0 +1,48 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+// !LANGUAGE: -InlineDefaultFunctionalParameters
+
+fun test() = "OK"
+
+val prop = "OK"
+
+class Foo {
+    fun test() = "OK"
+    val prop = "OK"
+}
+
+object FooObject {
+    fun test() = "OK"
+    val prop = "OK"
+}
+
+inline fun default1(s : () -> String = { "OK" }) {}
+inline fun default2(s : () -> String = ::test) {}
+inline fun default3(s : () -> String = ::prop) {}
+inline fun default4(s : () -> String = FooObject::test) {}
+inline fun default5(s : () -> String = FooObject::prop) {}
+inline fun default6(s : (a: Foo) -> String = Foo::test) {}
+inline fun default7(s : (a: Foo) -> String = Foo::prop) {}
+
+val a = Foo()
+
+inline fun default8(s : () -> String = a::test) {}
+inline fun default9(s : () -> String = a::prop) {}
+
+inline fun default10(s : () -> String = object : Function0<String> {
+    override fun invoke(): String {
+        return "FAIL"
+    }
+}) {}
+
+
+abstract class Base {
+    abstract fun foo(f: () -> Unit = { })
+}
+
+class Derived : Base() {
+    override final inline fun foo(f: () -> Unit) {
+        f()
+    }
+}
+
+inline fun default11(s : () -> Derived = ::Derived) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/defaultLambdaInlineSuspend.fir.kt b/compiler/testData/diagnostics/tests/inline/defaultLambdaInlineSuspend.fir.kt
new file mode 100644
index 00000000000..03209ab4197
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/defaultLambdaInlineSuspend.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -REDUNDANT_INLINE_SUSPEND_FUNCTION_TYPE -NOTHING_TO_INLINE
+// SKIP_TXT
+
+suspend inline fun test1(s : suspend () -> String = { "OK" }) {}
+suspend inline fun test2(s : () -> String = { "OK" }) {}
+suspend inline fun test3(crossinline s : suspend () -> String = { "OK" }) {}
+suspend inline fun test4(crossinline s : () -> String = { "OK" }) {}
+suspend inline fun test5(noinline s : suspend () -> String = { "OK" }) {}
+suspend inline fun test6(noinline s : () -> String = { "OK" }) {}
+
diff --git a/compiler/testData/diagnostics/tests/inline/defaultLambdaInlining.fir.kt b/compiler/testData/diagnostics/tests/inline/defaultLambdaInlining.fir.kt
new file mode 100644
index 00000000000..0836ab9ef8e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/defaultLambdaInlining.fir.kt
@@ -0,0 +1,47 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+// !LANGUAGE: +InlineDefaultFunctionalParameters
+
+fun test() = "OK"
+
+val prop = "OK"
+
+class Foo {
+    fun test() = "OK"
+    val prop = "OK"
+}
+
+object FooObject {
+    fun test() = "OK"
+    val prop = "OK"
+}
+
+inline fun default1(s : () -> String = {"OK"}) {}
+inline fun default2(s : () -> String = ::test) {}
+inline fun default3(s : () -> String = ::prop) {}
+inline fun default4(s : () -> String = FooObject::test) {}
+inline fun default5(s : () -> String = FooObject::prop) {}
+inline fun default6(s : (a: Foo) -> String = Foo::test) {}
+inline fun default7(s : (a: Foo) -> String = Foo::prop) {}
+
+val a = Foo()
+
+inline fun default8(s : () -> String = a::test) {}
+inline fun default9(s : () -> String = a::prop) {}
+
+inline fun default10(s : () -> String = object : Function0<String> {
+    override fun invoke(): String {
+        return "FAIL"
+    }
+}) {}
+
+abstract class Base {
+    abstract fun foo(f: () -> Unit = { })
+}
+
+class Derived : Base() {
+    override final inline fun foo(f: () -> Unit) {
+        f()
+    }
+}
+
+inline fun default11(s : () -> Derived = ::Derived) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/extensionOnFunction.fir.kt b/compiler/testData/diagnostics/tests/inline/extensionOnFunction.fir.kt
new file mode 100644
index 00000000000..6ab76240945
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/extensionOnFunction.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+infix fun Function1<Int, Unit>.noInlineExt(p: Int) {}
+
+inline infix fun Function1<Int, Unit>.inlineExt2(p: Int) {
+    noInlineExt(11)
+    this.noInlineExt(11)
+    this noInlineExt 11
+    this
+}
+
+inline fun Function1<Int, Unit>.inlineExt() {
+    inlineExt2(1)
+    this.inlineExt2(1)
+    this inlineExt2 1
+}
+
+inline fun testExtension(s: (p: Int) -> Unit) {
+    s.inlineExt()
+}
+
+inline fun inlineFunWrongExtension(s: (p: Int) -> Unit) {
+    s.noInlineExt(11)
+}
+
+inline fun inlineFunNoInline(noinline s: (p: Int) -> Unit) {
+    s.noInlineExt(11)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/fromInlineToNoInline.fir.kt b/compiler/testData/diagnostics/tests/inline/fromInlineToNoInline.fir.kt
new file mode 100644
index 00000000000..065f4c26ceb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/fromInlineToNoInline.fir.kt
@@ -0,0 +1,7 @@
+inline fun <R> onlyLocal(p: () -> R) {
+    inlineAll(p)
+}
+
+inline fun <R> inlineAll(noinline p: () -> R) {
+    p()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/functions.fir.kt b/compiler/testData/diagnostics/tests/inline/functions.fir.kt
new file mode 100644
index 00000000000..41bb698bd4f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/functions.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -UNNECESSARY_NOT_NULL_ASSERTION -UNNECESSARY_SAFE_CALL
+
+fun getFun(s: (p: Int) -> Unit): Function1<Int, Int> = {11}
+
+inline fun getInlineFun(s: (p: Int) -> Unit): Function1<Int, Int> = {11}
+
+inline fun testExtension(s: (p: Int) -> Unit) {
+    getFun(s).invoke(10)
+    getInlineFun(s).invoke(10)
+    getInlineFun(s)!!.invoke(10)
+    getInlineFun(s)?.invoke(10)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/inlineLambdaInDefaultInlineParameter.fir.kt b/compiler/testData/diagnostics/tests/inline/inlineLambdaInDefaultInlineParameter.fir.kt
new file mode 100644
index 00000000000..3ad7a5dce69
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/inlineLambdaInDefaultInlineParameter.fir.kt
@@ -0,0 +1,58 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+// !LANGUAGE: +InlineDefaultFunctionalParameters
+
+inline fun inlineFun(lambda: () -> String) = lambda()
+
+fun noInlineFun(lambda: () -> String) = lambda()
+
+
+inline fun default0_1(lambda: () -> String, dlambda: () -> String = { lambda; "OK" }) {
+    lambda() + dlambda()
+}
+
+inline fun default0_2(lambda: () -> String, dlambda: () -> String = { noInlineFun (lambda) }) {
+    lambda() + dlambda()
+}
+
+
+
+inline fun default0(lambda: () -> String, dlambda: () -> String = { noInlineFun (lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_0(lambda: () -> String, dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_1(lambda: () -> String, noinline dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_1crossinline(crossinline lambda: () -> String, noinline dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_2(noinline lambda: () -> String, dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_3(noinline lambda: () -> String, noinline dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+
+inline fun default2_1(lambda: () -> String, noinline dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default2_1crossinline(crossinline lambda: () -> String, noinline dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default2_2(noinline lambda: () -> String, dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default2_3(noinline lambda: () -> String, noinline dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/inlineLambdaInDefaultInlineParameterDisabled.fir.kt b/compiler/testData/diagnostics/tests/inline/inlineLambdaInDefaultInlineParameterDisabled.fir.kt
new file mode 100644
index 00000000000..8a831f8e5c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/inlineLambdaInDefaultInlineParameterDisabled.fir.kt
@@ -0,0 +1,61 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+// !LANGUAGE: -InlineDefaultFunctionalParameters
+
+inline fun inlineFun(lambda: () -> String) = lambda()
+
+fun noInlineFun(lambda: () -> String) = lambda()
+
+
+inline fun default0_1(lambda: () -> String, dlambda: () -> String = { lambda }) {
+    lambda() + dlambda()
+}
+
+inline fun default0_2(lambda: () -> String, dlambda: () -> String = { noInlineFun (lambda) }) {
+    lambda() + dlambda()
+}
+
+
+
+inline fun default1_0(lambda: () -> String, dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_1(lambda: () -> String, noinline dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_1crossinline(crossinline lambda: () -> String, noinline dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_2(noinline lambda: () -> String, dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+inline fun default1_3(noinline lambda: () -> String, noinline dlambda: () -> String = { lambda() }) {
+    lambda() + dlambda()
+}
+
+
+
+
+inline fun default2_0(lambda: () -> String, dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default2_1(lambda: () -> String, noinline dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default2_1crossinline(crossinline lambda: () -> String, noinline dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default2_2(noinline lambda: () -> String, dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
+
+inline fun default2_3(noinline lambda: () -> String, noinline dlambda: () -> String = { inlineFun(lambda) }) {
+    lambda() + dlambda()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/inlineReified.fir.kt b/compiler/testData/diagnostics/tests/inline/inlineReified.fir.kt
new file mode 100644
index 00000000000..c6a4332e529
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/inlineReified.fir.kt
@@ -0,0 +1,2 @@
+inline fun <T1, T2, reified T3, T4> foo(): T3 = null!!
+
diff --git a/compiler/testData/diagnostics/tests/inline/invoke.fir.kt b/compiler/testData/diagnostics/tests/inline/invoke.fir.kt
new file mode 100644
index 00000000000..45b96b57bbe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/invoke.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun inlineFunWithInvoke(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    s(11)
+    s.invoke(11)
+    s invoke 11
+
+    11.<!UNRESOLVED_REFERENCE!>ext<!>(11)
+    11 <!UNRESOLVED_REFERENCE!>ext<!> 11
+}
+
+inline fun inlineFunWithInvokeNonInline(noinline s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    s(11)
+    s.invoke(11)
+    s invoke 11
+
+    11.<!UNRESOLVED_REFERENCE!>ext<!>(11)
+    11 <!UNRESOLVED_REFERENCE!>ext<!> 11
+}
+
+inline fun Function1<Int, Unit>.inlineExt() {
+    invoke(11)
+    this.invoke(11)
+    this invoke 11
+    this(11)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/isCheck.fir.kt b/compiler/testData/diagnostics/tests/inline/isCheck.fir.kt
new file mode 100644
index 00000000000..e5c021a89dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/isCheck.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+inline public fun reg(converter: (Any) -> Any, flag: Boolean) {
+    flag
+    converter("")
+}
+
+public inline fun register(converter: (Any) -> Any) {
+    converter is (Any) -> Any
+    reg(converter, converter is (Any) -> Any)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/kt15410.fir.kt b/compiler/testData/diagnostics/tests/inline/kt15410.fir.kt
new file mode 100644
index 00000000000..5ab655383bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/kt15410.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class Foo protected constructor()
+
+inline fun foo(f: () -> Unit) = object: Foo() {}
+
+class A : Foo() {
+    inline fun foo(f: () -> Unit) = Foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/kt19679.fir.kt b/compiler/testData/diagnostics/tests/inline/kt19679.fir.kt
new file mode 100644
index 00000000000..4138c154f28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/kt19679.fir.kt
@@ -0,0 +1,4 @@
+inline fun test(s: () -> Unit, p: (() -> Unit)?) {
+    s()
+    p?.invoke()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/kt4869.fir.kt b/compiler/testData/diagnostics/tests/inline/kt4869.fir.kt
new file mode 100644
index 00000000000..5fc9d07399f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/kt4869.fir.kt
@@ -0,0 +1,6 @@
+inline fun foo(f: () -> Unit) {
+    val ff = { f: () -> Unit ->
+        f.invoke()
+    }
+    ff(f)
+}
diff --git a/compiler/testData/diagnostics/tests/inline/labeled.fir.kt b/compiler/testData/diagnostics/tests/inline/labeled.fir.kt
new file mode 100644
index 00000000000..b991c098c68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/labeled.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+inline fun foo(bar1: (String.() -> Int) -> Int, bar2: (()->Int) -> Int) {
+    bar1 label@ {
+        this@label.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    bar1 {
+        this.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    //unmute after KT-4247 fix
+    //bar1  {
+    //    this@bar1.length
+    //}
+
+    bar2 l@ {
+        11
+    }
+
+    bar2 {
+        12
+    }
+
+}
+
+inline fun foo2(bar1: (String.() -> Int) -> Int) {
+    l1@ bar1
+
+    l2@ bar1 {
+        11
+    }
+
+    (l3@ bar1) {
+        11
+    }
+
+    (l5@ (l4@ bar1)) {
+        11
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/lambdaCast.fir.kt b/compiler/testData/diagnostics/tests/inline/lambdaCast.fir.kt
new file mode 100644
index 00000000000..af524ecd3c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/lambdaCast.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNCHECKED_CAST -USELESS_CAST
+inline public fun reg(convertFunc: (Any) -> Any) {
+    convertFunc("")
+}
+
+public inline fun <reified T : Any, reified R : Any> register(converter: (T) -> R) {
+    converter as (Any) -> Any
+    reg(converter as (Any) -> Any)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/localFun.fir.kt b/compiler/testData/diagnostics/tests/inline/localFun.fir.kt
new file mode 100644
index 00000000000..7b15da005a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/localFun.fir.kt
@@ -0,0 +1,4 @@
+fun main() {
+    inline fun a(){
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/messagesForUnsupportedInInline.fir.kt b/compiler/testData/diagnostics/tests/inline/messagesForUnsupportedInInline.fir.kt
new file mode 100644
index 00000000000..0c368ac56ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/messagesForUnsupportedInInline.fir.kt
@@ -0,0 +1,18 @@
+inline fun inlineFun() {
+    fun localFun() {}
+    class LocalClass {}
+}
+
+fun outerFun() {
+    inline fun localInlineFun() {}
+}
+
+abstract class Base {
+    abstract fun withDefault(f: () -> Unit = { -> })
+}
+
+class Derived : Base() {
+    override final inline fun withDefault(
+            f: () -> Unit
+    ) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/anonymousObjects.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/anonymousObjects.fir.kt
new file mode 100644
index 00000000000..39a8ec3d9cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/anonymousObjects.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun <R> inlineFunOnlyLocal(crossinline p: () -> R) {
+    val s = object {
+
+        val z = p()
+
+        fun a() {
+            p()
+        }
+    }
+}
+
+inline fun <R> inlineFun(p: () -> R) {
+    val s = object {
+
+        val z = p()
+
+        fun a() {
+            p()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/anonymousObjectsNested.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/anonymousObjectsNested.fir.kt
new file mode 100644
index 00000000000..e068f2a91d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/anonymousObjectsNested.fir.kt
@@ -0,0 +1,48 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun <R> inlineFunOnlyLocal(crossinline p: () -> R) {
+    val s = object {
+
+        val z = p();
+
+        init {
+            doCall {
+                p()
+            }
+        }
+
+        fun a() {
+            doCall {
+                p()
+            }
+
+            p()
+        }
+    }
+}
+
+inline fun <R> inlineFun(p: () -> R) {
+    val s = object {
+
+        val z = p()
+
+        init {
+            doCall {
+                p()
+            }
+        }
+
+
+        fun a() {
+            doCall {
+                p()
+            }
+
+            p()
+        }
+    }
+}
+
+inline fun <R> doCall(p: () -> R) {
+    p()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/explicitReturnType.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/explicitReturnType.fir.kt
new file mode 100644
index 00000000000..e11a8fc6dcb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/explicitReturnType.fir.kt
@@ -0,0 +1,41 @@
+fun inlineCallExplicitError(): String {
+    inlineFun lamba@ {
+        if (true) {
+            return@lamba 2
+        }
+        1
+    }
+
+    return "x"
+}
+
+fun inlineCall(): String {
+    inlineFun lamba@ {
+        if (true) {
+            return@lamba 2
+        }
+        1
+    }
+
+    return "x"
+}
+
+inline fun inlineFun(s: () -> Int) {
+    s()
+}
+
+
+fun noInlineCall(): String {
+    noInline lambda@ {
+        if (true) {
+            return@lambda 2
+        }
+        1
+    }
+    return "x"
+}
+
+
+fun noInline(s: () -> Int) {
+    s()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/fromOnlyLocal.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/fromOnlyLocal.fir.kt
new file mode 100644
index 00000000000..d6c0ad89ff2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/fromOnlyLocal.fir.kt
@@ -0,0 +1,8 @@
+
+inline fun <R> onlyLocal(crossinline p: () -> R) {
+    inlineAll(p)
+}
+
+inline fun <R> inlineAll(p: () -> R) {
+    p()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/inlineLambda.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/inlineLambda.fir.kt
new file mode 100644
index 00000000000..094bfabab41
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/inlineLambda.fir.kt
@@ -0,0 +1,16 @@
+
+inline fun <R> inlineFunWithAnnotation(crossinline p: () -> R) {
+    inlineFun {
+        p()
+    }
+}
+
+inline fun <R> inlineFun2(p: () -> R) {
+    inlineFun {
+        p()
+    }
+}
+
+inline fun <R> inlineFun(p: () -> R) {
+    p()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/labeledReturn.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/labeledReturn.fir.kt
new file mode 100644
index 00000000000..4b290879ed1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/labeledReturn.fir.kt
@@ -0,0 +1,31 @@
+fun inlineCall(): String {
+    inlineFun {
+        if (true) {
+            return@inlineCall ""
+        }
+        1
+    }
+
+    return "x"
+}
+
+inline fun inlineFun(s: ()->Int) {
+    s()
+}
+
+
+fun noInlineCall(): String {
+    noInline {
+        if (true) {
+            return@noInlineCall ""
+        }
+        1
+    }
+
+    return "x"
+}
+
+
+fun noInline(s: ()->Int) {
+    s()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaAsGeneric.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaAsGeneric.fir.kt
new file mode 100644
index 00000000000..acb2535e663
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaAsGeneric.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+
+fun box() : String {
+    test {
+        return@box "123"
+    }
+
+    return "OK"
+}
+
+inline fun <T> test(p: T) {
+    p.toString()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaAsNonFunction.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaAsNonFunction.fir.kt
new file mode 100644
index 00000000000..438220488c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaAsNonFunction.fir.kt
@@ -0,0 +1,11 @@
+fun box() : String {
+    test {
+        return@box "123"
+    }
+
+    return "OK"
+}
+
+inline fun test(p: Any) {
+    p.toString()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaWithGlobalReturnsInsideOnlyLocalOne.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaWithGlobalReturnsInsideOnlyLocalOne.fir.kt
new file mode 100644
index 00000000000..37a7935c201
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/lambdaWithGlobalReturnsInsideOnlyLocalOne.fir.kt
@@ -0,0 +1,9 @@
+
+inline fun testSameCaptured(lambdaWithResultCaptured: () -> Unit) : String {
+    doWork({lambdaWithResultCaptured()})
+    return "OK"
+}
+
+inline fun <R> doWork(crossinline job: ()-> R) : R {
+    return job()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/localFun.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/localFun.fir.kt
new file mode 100644
index 00000000000..63f60ab4e35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/localFun.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun <R> inlineFunOnlyLocal(crossinline p: () -> R) {
+    fun a() {
+        val z = p()
+    }
+    a()
+}
+
+inline fun <R> inlineFun(p: () -> R) {
+    fun a() {
+        p()
+    }
+    a()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/nestedNonLocals.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/nestedNonLocals.fir.kt
new file mode 100644
index 00000000000..023306d08b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/nestedNonLocals.fir.kt
@@ -0,0 +1,41 @@
+import Kind.EXT_RETURN
+import Kind.GLOBAL_RETURN
+
+enum class Kind {
+    LOCAL,
+    EXT_RETURN,
+    GLOBAL_RETURN
+}
+
+class Internal(val value: String)
+
+class External(val value: String)
+
+class Global(val value: String)
+
+fun test1(intKind: Kind, extKind: Kind): Global {
+
+    var externalResult = doCall ext@ {
+
+        val internalResult = doCall int@ {
+            if (intKind == Kind.LOCAL) {
+                return@test1 Global("internal to global")
+            } else if (intKind == EXT_RETURN) {
+                return@ext External("internal to external")
+            }
+            return@int Internal("internal to local")
+        }
+
+        if (extKind == GLOBAL_RETURN || extKind == EXT_RETURN) {
+            return Global("external to global")
+        }
+
+        External(internalResult.value + " to local");
+    }
+
+    return Global(externalResult.value + " to exit")
+}
+
+public inline fun <R> doCall(block: ()-> R) : R {
+    return block()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/noInlineAnnotation.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/noInlineAnnotation.fir.kt
new file mode 100644
index 00000000000..f6a5b2ec051
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/noInlineAnnotation.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+fun main() {
+    test {
+        return
+    }
+}
+
+inline fun test(noinline lambda: () -> Unit) {
+    lambda()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/noInlineLambda.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/noInlineLambda.fir.kt
new file mode 100644
index 00000000000..bc5293f974d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/noInlineLambda.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun <R> inlineFunOnlyLocal(crossinline p: () -> R) {
+    <!UNRESOLVED_REFERENCE!>{
+        p()
+    }()<!>
+}
+
+inline fun <R> inlineFun(p: () -> R) {
+    <!UNRESOLVED_REFERENCE!>{
+        p()
+    }()<!>
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/nonInlinedClass.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/nonInlinedClass.fir.kt
new file mode 100644
index 00000000000..df9dbafb8d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/nonInlinedClass.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun <R> inlineFunOnlyLocal(crossinline p: () -> R) {
+    class A {
+
+        val z = p()
+
+        fun a() {
+            p()
+        }
+    }
+}
+
+inline fun <R> inlineFun(p: () -> R) {
+    class A {
+
+        val z = p()
+
+        fun a() {
+            p()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/onlyLocalReturnLambda.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/onlyLocalReturnLambda.fir.kt
new file mode 100644
index 00000000000..c4419fdb152
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/onlyLocalReturnLambda.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+fun <R> fun1(p: () -> R) {
+    inlineFun {
+        p()
+    }
+}
+
+fun <R> fun1ValueArgument(p: () -> R) {
+    inlineFun ({
+                   p()
+               })
+}
+
+fun <R> fun3(p: () -> R) {
+    inlineFun {
+        return;
+    }
+}
+
+fun <R> fun3ValueArgument(p: () -> R) {
+    inlineFun ({
+                   return;
+               })
+}
+
+
+fun <R> fun4(p: () -> R) {
+    inlineFun lambda@ {
+        return@lambda p();
+    }
+}
+
+fun <R> fun4ValueArgument(p: () -> R) {
+    inlineFun (lambda@ {
+        return@lambda p();
+    })
+}
+
+
+inline fun <R> inlineFun(crossinline p: () -> R) {
+    p()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/onlyLocalReturnLambdaBinaryExpr.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/onlyLocalReturnLambdaBinaryExpr.fir.kt
new file mode 100644
index 00000000000..5a0533c202b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/onlyLocalReturnLambdaBinaryExpr.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+class Z {
+    <!INAPPLICABLE_INFIX_MODIFIER!>inline infix fun <R> inlineFun(crossinline p: () -> R) {
+        p()
+    }<!>
+}
+
+fun <R> fun1(p: () -> R) {
+    Z() inlineFun {
+        p()
+    }
+}
+
+fun <R> fun3(p: () -> R) {
+    Z() inlineFun {
+        return;
+    }
+}
+
+fun <R> fun4(p: () -> R) {
+    Z() inlineFun lambda@ {
+        return@lambda p();
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/propertyAccessorsAndConstructor.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/propertyAccessorsAndConstructor.fir.kt
new file mode 100644
index 00000000000..d5449715989
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/propertyAccessorsAndConstructor.fir.kt
@@ -0,0 +1,24 @@
+inline fun <R> doCall(p: () -> R) {
+    p()
+}
+
+inline fun <R> doCallInt(p: () -> R): R {
+    return p()
+}
+
+class A {
+    var result: Int = doCallInt { return this };
+
+    var field: Int
+        get() {
+            doCall { return 1 }
+            return 2
+        }
+        set(v: Int) {
+            doCall {
+                result = v / 2
+                return
+            }
+            result = v
+        }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonLocalReturns/toOnlyLocal.fir.kt b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/toOnlyLocal.fir.kt
new file mode 100644
index 00000000000..8970e751c2b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonLocalReturns/toOnlyLocal.fir.kt
@@ -0,0 +1,8 @@
+
+inline fun <R> toOnlyLocal(crossinline p: () -> R) {
+    p()
+}
+
+inline fun <R> inlineAll(p: () -> R) {
+    toOnlyLocal(p)
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/inNonPublicClass.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inNonPublicClass.fir.kt
new file mode 100644
index 00000000000..850af038fae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inNonPublicClass.fir.kt
@@ -0,0 +1,47 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -PRIVATE_CLASS_MEMBER_FROM_INLINE
+private class Z public constructor(){
+    public val publicProperty:Int = 12
+    public fun publicFun() {}
+}
+
+public inline fun test() {
+    Z().publicProperty
+    Z().publicFun()
+}
+
+internal inline fun testInternal() {
+    Z().publicProperty
+    Z().publicFun()
+}
+
+internal class Z2 {
+    private val privateProperty = 11;
+
+    public val publicProperty:Int = 12
+
+    private fun privateFun() {}
+
+    public fun publicFun() {}
+
+    public inline fun test() {
+        privateProperty
+        privateFun()
+        publicProperty
+        publicFun()
+        Z2().publicProperty
+        Z2().publicFun()
+        Z2().privateProperty
+        Z2().privateFun()
+    }
+
+    internal inline fun testInternal() {
+        privateProperty
+        privateFun()
+        publicProperty
+        publicFun()
+        Z2().publicProperty
+        Z2().publicFun()
+        Z2().privateProperty
+        Z2().privateFun()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/inNonPublicInnerClass.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inNonPublicInnerClass.fir.kt
new file mode 100644
index 00000000000..78f956bd84c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inNonPublicInnerClass.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+internal class Z2 {
+    private val privateProperty = 11;
+
+    public val publicProperty:Int = 12
+
+    private fun privateFun() {}
+
+    public fun publicFun() {}
+
+    internal inner class ZInner {
+        public inline fun test() {
+            privateProperty
+            privateFun()
+            publicFun()
+            publicProperty
+
+            Z2().publicProperty
+            Z2().publicFun()
+            Z2().privateProperty
+            Z2().privateFun()
+        }
+
+        internal inline fun testInternal() {
+            privateProperty
+            privateFun()
+            publicFun()
+            publicProperty
+
+            Z2().publicProperty
+            Z2().publicFun()
+            Z2().privateProperty
+            Z2().privateFun()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/inPackage.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inPackage.fir.kt
new file mode 100644
index 00000000000..4278490afdb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inPackage.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+private val privateProperty = 11;
+private fun privateFun() {}
+
+internal val internalProperty = 11;
+internal fun internalFun() {}
+
+public inline fun test() {
+    privateFun()
+    privateProperty
+}
+
+public inline fun test2() {
+    internalFun()
+    internalProperty
+}
+
+internal inline fun testInternal() {
+    privateFun()
+    privateProperty
+}
+
+internal inline fun test2Internal() {
+    internalFun()
+    internalProperty
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/inPublicClass.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inPublicClass.fir.kt
new file mode 100644
index 00000000000..b58a7e8d0ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/inPublicClass.fir.kt
@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+public class Z {
+    internal val privateProperty = 11;
+
+    internal fun privateFun() {
+
+    }
+}
+
+public inline fun test() {
+    Z().privateProperty
+    Z().privateFun()
+}
+
+internal inline fun testInternal() {
+    Z().privateProperty
+    Z().privateFun()
+}
+
+
+public class Z2 {
+    private val privateProperty = 11;
+
+    private fun privateFun() {
+
+    }
+
+    public inline fun test() {
+        privateProperty
+        privateFun()
+    }
+
+    internal inline fun testInternal() {
+        privateProperty
+        privateFun()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/kt14887.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/kt14887.fir.kt
new file mode 100644
index 00000000000..60b03648e04
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/kt14887.fir.kt
@@ -0,0 +1,8 @@
+inline fun foo() {
+    <!UNRESOLVED_REFERENCE!>unresolved<!>().<!UNRESOLVED_REFERENCE!>another<!>
+    <!UNRESOLVED_REFERENCE!>unresolved<!>().<!UNRESOLVED_REFERENCE!>another<!>()
+}
+
+fun main() {
+    foo()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/localClass.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/localClass.fir.kt
new file mode 100644
index 00000000000..5f3c49341f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/localClass.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -NOTHING_TO_INLINE
+
+public class Z {
+    private val privateProperty = 11;
+
+    public fun privateFun() {
+
+        class Local {
+            public inline fun a() {
+                <!UNRESOLVED_REFERENCE!>privateProperty<!>
+            }
+        }
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/localClass2.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/localClass2.fir.kt
new file mode 100644
index 00000000000..9c8142c5777
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/localClass2.fir.kt
@@ -0,0 +1,13 @@
+public fun test() {
+
+    class Z {
+        public fun localFun() {
+
+        }
+    }
+
+    inline fun localFun2() {
+        Z().localFun()
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/localFun.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/localFun.fir.kt
new file mode 100644
index 00000000000..513803471a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/localFun.fir.kt
@@ -0,0 +1,11 @@
+public fun test() {
+
+    fun localFun() {
+
+    }
+
+    inline fun localFun2() {
+        localFun()
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonPublicMember/publishedApi.fir.kt b/compiler/testData/diagnostics/tests/inline/nonPublicMember/publishedApi.fir.kt
new file mode 100644
index 00000000000..0848d0d9506
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonPublicMember/publishedApi.fir.kt
@@ -0,0 +1,48 @@
+// !DIAGNOSTICS: -EXPOSED_PARAMETER_TYPE -NOTHING_TO_INLINE
+
+
+inline fun call(a: A) {
+    a.test()
+
+    privateFun()
+
+    internalFun()
+}
+
+@PublishedApi
+internal inline fun callFromPublishedApi(a: A) {
+    a.test()
+
+    privateFun()
+
+    internalFun()
+}
+
+internal class A {
+    @PublishedApi
+    internal fun test() {
+        test()
+
+        privateFun()
+
+        internalFun()
+    }
+
+    @PublishedApi
+    internal fun testInline() {
+        test()
+
+        privateFun()
+
+        internalFun()
+    }
+}
+
+
+private fun privateFun() {
+
+}
+
+internal fun internalFun() {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nonVirtualMembersWithInline.fir.kt b/compiler/testData/diagnostics/tests/inline/nonVirtualMembersWithInline.fir.kt
new file mode 100644
index 00000000000..fb437750c26
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nonVirtualMembersWithInline.fir.kt
@@ -0,0 +1,47 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline private fun a() {}
+
+inline fun b() {}
+
+inline public fun c() {}
+
+abstract class A {
+    inline private fun good1() {}
+    inline public final fun good2() {}
+    inline protected final fun good3() {}
+    inline final fun good4() {}
+
+
+    inline open protected fun wrong1() {}
+
+    inline open public fun wrong2() {}
+
+    inline open fun wrong3() {}
+
+    inline abstract protected fun wrong4()
+
+    inline abstract public fun wrong5()
+
+    inline abstract fun wrong6()
+}
+
+
+interface B {
+
+    inline private fun good1() {}
+
+    inline fun wrong1() {}
+
+    inline open fun wrong2() {}
+
+    inline open public fun wrong3() {}
+
+    inline open fun wrong4() {}
+
+    inline fun wrong5()
+
+    inline public fun wrong6()
+
+    inline fun wrong7()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/nothingToInline.fir.kt b/compiler/testData/diagnostics/tests/inline/nothingToInline.fir.kt
new file mode 100644
index 00000000000..69f22f45b25
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nothingToInline.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NULLABLE_INLINE_PARAMETER -CONFLICTING_JVM_DECLARATIONS
+
+inline fun test() {
+
+}
+
+inline fun test2(s : (Int) -> Int) {
+
+}
+
+inline fun test3(noinline s : (Int) -> Int) {
+
+}
+
+inline fun test4(noinline s : Int.() -> Int) {
+
+}
+
+inline fun Function1<Int, Int>?.test5() {
+
+}
+
+inline fun Function1<Int, Int>?.test6() {
+
+}
+
+inline fun test2(s : ((Int) -> Int)?) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nullabilityOperations.fir.kt b/compiler/testData/diagnostics/tests/inline/nullabilityOperations.fir.kt
new file mode 100644
index 00000000000..176f08f96ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nullabilityOperations.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNNECESSARY_SAFE_CALL -UNNECESSARY_NOT_NULL_ASSERTION -CONFLICTING_JVM_DECLARATIONS
+inline fun String.submit(action: Function1<Int, Int>) {
+
+}
+
+inline fun Function1<Int, Int>.submit() {
+    this?.invoke(11)
+    this!!.invoke(11)
+
+    submit(this!!)
+}
+
+inline fun submit(action: Function1<Int, Int>) {
+    action?.invoke(10)
+    action!!.invoke(10)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/nullableFunction.fir.kt b/compiler/testData/diagnostics/tests/inline/nullableFunction.fir.kt
new file mode 100644
index 00000000000..5d81a507901
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/nullableFunction.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -CONFLICTING_JVM_DECLARATIONS
+
+public inline fun <T> Function1<Int, Int>?.submit(action: ()->T) {
+    this?.invoke(11)
+}
+
+public inline fun <T> submit(action: Function1<Int, Int>?, s: () -> Int) {
+    action?.invoke(10)
+}
+
+public inline fun <T> submitNoInline(noinline action: Function1<Int, Int>?, s: () -> Int) {
+    action?.invoke(10)
+}
+
+public inline fun <T> Function1<Int, Int>?.submit() {
+
+}
+
+public inline fun <T> submit(action: Function1<Int, Int>?) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/overrideWithInline.fir.kt b/compiler/testData/diagnostics/tests/inline/overrideWithInline.fir.kt
new file mode 100644
index 00000000000..ee3753a83a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/overrideWithInline.fir.kt
@@ -0,0 +1,60 @@
+// !DIAGNOSTICS: -NOTHING_TO_INLINE -UNUSED_PARAMETER
+
+interface IBase {
+    fun foo()
+    fun bar()
+    fun <T> qux(x: T)
+}
+
+class CDerived : IBase {
+    override inline final fun foo() {}
+    override inline fun bar() {}
+    override inline final fun <reified T> qux(x: T) {}
+
+    class CNested : IBase {
+        override inline final fun foo() {}
+        override inline fun bar() {}
+        override inline final fun <reified T> qux(x: T) {}
+    }
+
+    val anObject = object : IBase {
+        override inline final fun foo() {}
+        override inline fun bar() {}
+        override inline final fun <reified T> qux(x: T) {}
+    }
+
+    fun aMethod() {
+        class CLocal : IBase {
+            override inline final fun foo() {}
+            override inline fun bar() {}
+            override inline final fun <reified T> qux(x: T) {}
+        }
+    }
+}
+
+open class COpen : IBase {
+    override inline final fun foo() {}
+    override inline fun bar() {}
+    override inline final fun <reified T> qux(x: T) {}
+
+    open class COpenNested : IBase {
+        override inline final fun foo() {}
+        override inline fun bar() {}
+        override inline final fun <reified T> qux(x: T) {}
+    }
+
+    val anObject = object : IBase {
+        override inline final fun foo() {}
+        override inline fun bar() {}
+        override inline final fun <reified T> qux(x: T) {}
+    }
+
+    fun aMethod() {
+        open class COpenLocal : IBase {
+            override inline final fun foo() {}
+            override inline fun bar() {}
+            override inline final fun <reified T> qux(x: T) {}
+        }
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/inline/parenthesized.fir.kt b/compiler/testData/diagnostics/tests/inline/parenthesized.fir.kt
new file mode 100644
index 00000000000..fd3aaf8e3ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/parenthesized.fir.kt
@@ -0,0 +1,27 @@
+// !CHECK_TYPE
+
+inline fun inlineFunWithInvoke(s: (p: Int) -> Unit) {
+    (s)(11)
+    (s).invoke(11)
+    (s) invoke 11
+    (s)
+}
+
+inline fun Function1<Int, Unit>.inlineExt() {
+    (this).invoke(11)
+    (this) invoke 11
+    (this)(11)
+    (this)
+}
+
+inline fun inlineFunWithInvoke2(s: (p: Int) -> Unit) {
+    (((s)))(11)
+    (((s))).invoke(11)
+    (((s))) invoke 11
+    (((s)))
+}
+
+inline fun propagation(s: (p: Int) -> Unit) {
+    inlineFunWithInvoke((label@ s))
+    inlineFunWithInvoke((label2@ label@ s))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/privateClass.fir.kt b/compiler/testData/diagnostics/tests/inline/privateClass.fir.kt
new file mode 100644
index 00000000000..34c743b800b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/privateClass.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -EXPOSED_PARAMETER_TYPE
+
+private class S public constructor() {
+    fun a() {
+
+    }
+}
+
+internal inline fun x(s: S, z: () -> Unit) {
+    z()
+    S()
+    s.a()
+    test()
+}
+
+private inline fun x2(s: S, z: () -> Unit) {
+    z()
+    S()
+    s.a()
+    test()
+}
+
+private fun test(): S {
+    return S()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/propagation.fir.kt b/compiler/testData/diagnostics/tests/inline/propagation.fir.kt
new file mode 100644
index 00000000000..3faba489acd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/propagation.fir.kt
@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -NON_LOCAL_RETURN_NOT_ALLOWED
+
+inline fun inlineFunWithInvoke(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    subInline(s, ext)
+    subNoInline(s, ext)
+}
+
+inline fun inlineFunWithInvokeClosure(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    subInline({p: Int -> s(p)}, { p -> this.<!UNRESOLVED_REFERENCE!>ext<!>(p)})
+    subNoInline({p: Int -> s(p)}, { p -> this.<!UNRESOLVED_REFERENCE!>ext<!>(p)})
+}
+
+//No inline
+inline fun inlineFunWithInvokeNonInline(noinline s: (p: Int) -> Unit, noinline ext: Int.(p: Int) -> Unit) {
+    subInline(s, ext)
+    subNoInline(s, ext)
+}
+
+inline fun inlineFunWithInvokeClosureNoinline(noinline s: (p: Int) -> Unit, noinline ext: Int.(p: Int) -> Unit) {
+    subInline({p: Int -> s(p)}, { p -> this.<!UNRESOLVED_REFERENCE!>ext<!>(p)})
+    subNoInline({p: Int -> s(p)}, { p -> this.<!UNRESOLVED_REFERENCE!>ext<!>(p)})
+}
+
+//ext function
+inline fun Function1<Int, Unit>.inlineExt(ext: Int.(p: Int) -> Unit) {
+    subInline(this, ext)
+    subNoInline(this, ext)
+}
+
+inline fun Function1<Int, Unit>.inlineExtWithClosure(ext: Int.(p: Int) -> Unit) {
+    subInline({p: Int -> this(p)}, { p -> this.<!UNRESOLVED_REFERENCE!>ext<!>(p)})
+    subNoInline({p: Int -> this(p)}, { p -> this.<!UNRESOLVED_REFERENCE!>ext<!>(p)})
+}
+
+inline fun subInline(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {}
+
+fun subNoInline(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {}
diff --git a/compiler/testData/diagnostics/tests/inline/property/invoke.fir.kt b/compiler/testData/diagnostics/tests/inline/property/invoke.fir.kt
new file mode 100644
index 00000000000..f0f11d69994
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/property/invoke.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -INFIX_MODIFIER_REQUIRED
+
+inline var value: (p: Int) -> String
+    get() = {"123" }
+    set(s: (p: Int) -> String) {
+        s(11)
+        s.invoke(11)
+        s invoke 11
+
+        val z = s
+    }
+
+inline var value2: Int.(p: Int) -> String
+    get() = {"123" }
+    set(ext: Int.(p: Int) -> String) {
+        11.<!UNRESOLVED_REFERENCE!>ext<!>(11)
+        11.<!UNRESOLVED_REFERENCE!>ext<!>(11)
+
+        val p = ext
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/property/propertyWithBackingField.fir.kt b/compiler/testData/diagnostics/tests/inline/property/propertyWithBackingField.fir.kt
new file mode 100644
index 00000000000..d857444247e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/property/propertyWithBackingField.fir.kt
@@ -0,0 +1,21 @@
+// WITH_REFLECT
+
+import kotlin.reflect.KProperty
+
+class Delegate {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int = 1
+}
+
+open class A {
+    inline val z1 = 1
+
+    val z1_1 = 1
+        inline get() = field + 1
+
+    inline var z2 = 1
+
+    var z2_1 = 1
+        inline set(p: Int) {}
+
+    inline val z by Delegate()
+}
diff --git a/compiler/testData/diagnostics/tests/inline/property/unsupportedConstruction.fir.kt b/compiler/testData/diagnostics/tests/inline/property/unsupportedConstruction.fir.kt
new file mode 100644
index 00000000000..a97b55cd40a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/property/unsupportedConstruction.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline val z: Int
+    get()  {
+
+    class A {
+        fun a() {
+           class AInner {}
+        }
+    }
+
+    object B{
+        object BInner {}
+    }
+
+    fun local() {
+        fun localInner() {}
+    }
+    return 1
+}
diff --git a/compiler/testData/diagnostics/tests/inline/property/virtualProperty.fir.kt b/compiler/testData/diagnostics/tests/inline/property/virtualProperty.fir.kt
new file mode 100644
index 00000000000..e95efd83238
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/property/virtualProperty.fir.kt
@@ -0,0 +1,38 @@
+final class FinalProperty {
+    inline val valProp: Int
+        get() = 1
+
+    val valProp_1: Int
+        inline get() = 1
+
+    inline var varProp: Int
+        get() = 1
+        set(p: Int) {}
+
+    var varProp_2: Int
+        get() = 1
+        inline set(p: Int) {}
+}
+
+
+open class OpenProperty {
+    inline open val valProp: Int
+        get() = 1
+
+    open val valProp_1: Int
+        inline get() = 1
+
+    inline open var varProp: Int
+        get() = 1
+        set(p: Int) {}
+
+    open var varProp_2: Int
+        get() = 1
+        inline set(p: Int) {}
+}
+
+
+interface AbstractProperty {
+    inline abstract val valProp: Int
+    inline abstract var varProp: Int
+}
diff --git a/compiler/testData/diagnostics/tests/inline/protectedCallDepecation.fir.kt b/compiler/testData/diagnostics/tests/inline/protectedCallDepecation.fir.kt
new file mode 100644
index 00000000000..c6137f3ccdc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/protectedCallDepecation.fir.kt
@@ -0,0 +1,102 @@
+// !LANGUAGE: -ProhibitProtectedCallFromInline
+// !DIAGNOSTICS: -EXPOSED_PARAMETER_TYPE -NOTHING_TO_INLINE
+
+// FILE: JavaClass.java
+
+
+public abstract class JavaClass {
+    protected void bind() {}
+}
+
+// FILE: main.kt
+open class A {
+    protected fun test() {}
+
+    protected val z: String = "1"
+
+    public var zVar: String = "1"
+        protected set(value) {}
+
+    inline fun call() {
+        test()
+        z
+        zVar
+        zVar = "123"
+    }
+
+    internal inline fun callFromInternal() {
+        test()
+        zVar
+        zVar = "123"
+    }
+
+    @PublishedApi
+    internal inline fun callFromPublished() {
+        test()
+        z
+        zVar
+        zVar = "123"
+    }
+
+    protected inline fun callFromProtected() {
+        test()
+        zVar
+        zVar = "123"
+    }
+
+}
+
+class B : A() {
+    inline fun testB() {
+        test()
+    }
+}
+
+class C : JavaClass() {
+    inline fun call() {
+        bind()
+    }
+
+    internal inline fun callFromInternal() {
+        bind()
+    }
+
+    protected inline fun callFromProtected() {
+        bind()
+    }
+
+    @PublishedApi
+    internal inline fun callFromPublished() {
+        bind()
+    }
+}
+
+
+internal class AInternal {
+    protected fun test() {}
+
+    protected val z: String = "1"
+
+    public var zVar: String = "1"
+        protected set(value) {}
+
+
+    inline fun call() {
+        test()
+    }
+
+    @PublishedApi
+    internal inline fun call2() {
+        test()
+    }
+}
+
+private class X {
+
+    public class Z : A() {
+        public inline fun effictivelyNonPublic() {
+            test()
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/protectedCallError.fir.kt b/compiler/testData/diagnostics/tests/inline/protectedCallError.fir.kt
new file mode 100644
index 00000000000..a3dec4dfa8e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/protectedCallError.fir.kt
@@ -0,0 +1,102 @@
+// !LANGUAGE: +ProhibitProtectedCallFromInline
+// !DIAGNOSTICS: -EXPOSED_PARAMETER_TYPE -NOTHING_TO_INLINE
+
+// FILE: JavaClass.java
+
+
+public abstract class JavaClass {
+    protected void bind() {}
+}
+
+// FILE: main.kt
+open class A {
+    protected fun test() {}
+
+    protected val z: String = "1"
+
+    public var zVar: String = "1"
+        protected set(value) {}
+
+    inline fun call() {
+        test()
+        z
+        zVar
+        zVar = "123"
+    }
+
+    internal inline fun callFromInternal() {
+        test()
+        zVar
+        zVar = "123"
+    }
+
+    @PublishedApi
+    internal inline fun callFromPublished() {
+        test()
+        z
+        zVar
+        zVar = "123"
+    }
+
+    protected inline fun callFromProtected() {
+        test()
+        zVar
+        zVar = "123"
+    }
+
+}
+
+class B : A() {
+    inline fun testB() {
+        test()
+    }
+}
+
+class C : JavaClass() {
+    inline fun call() {
+        bind()
+    }
+
+    internal inline fun callFromInternal() {
+        bind()
+    }
+
+    protected inline fun callFromProtected() {
+        bind()
+    }
+
+    @PublishedApi
+    internal inline fun callFromPublished() {
+        bind()
+    }
+}
+
+
+internal class AInternal {
+    protected fun test() {}
+
+    protected val z: String = "1"
+
+    public var zVar: String = "1"
+        protected set(value) {}
+
+
+    inline fun call() {
+        test()
+    }
+
+    @PublishedApi
+    internal inline fun call2() {
+        test()
+    }
+}
+
+private class X {
+
+    public class Z : A() {
+        public inline fun effictivelyNonPublic() {
+            test()
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/publishedApi.fir.kt b/compiler/testData/diagnostics/tests/inline/publishedApi.fir.kt
new file mode 100644
index 00000000000..ad214321f3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/publishedApi.fir.kt
@@ -0,0 +1,175 @@
+// !DIAGNOSTICS: -EXPOSED_PARAMETER_TYPE -NOTHING_TO_INLINE
+inline fun call(a: A) {
+    a.test()
+    publishedTopLevel()
+    
+    a.publishedVar
+    a.publishedVar = 1
+
+    publishedVarTopLevel
+    publishedVarTopLevel = 1
+}
+
+inline var inlineVar: Int
+    get() {
+        val a = A()
+        a.test()
+        publishedTopLevel()
+
+        a.publishedVar
+        a.publishedVar = 1
+
+        publishedVarTopLevel
+        publishedVarTopLevel = 1
+        return 1
+    }
+    set(value) {
+        val a = A()
+        a.test()
+        publishedTopLevel()
+
+        a.publishedVar
+        a.publishedVar = 1
+
+        publishedVarTopLevel
+        publishedVarTopLevel = 1
+    }
+
+@PublishedApi
+internal class A {
+    @PublishedApi
+    internal fun test() {
+        publicFun()
+        internalFun()
+        privateFun()
+
+        publicVarTopLevel
+        publicVarTopLevel = 1
+        internalVarTopLevel
+        internalVarTopLevel = 1
+        privateVarTopLevel
+        privateVarTopLevel = 1
+
+        publishedVar
+        publishedVar = 1
+    }
+
+    @PublishedApi
+    internal inline fun testInline() {
+        publicFun()
+        internalFun()
+        privateFun()
+
+        publicVarTopLevel
+        publicVarTopLevel = 1
+        internalVarTopLevel
+        internalVarTopLevel = 1
+        privateVarTopLevel
+        privateVarTopLevel = 1
+
+        publishedVar
+        publishedVar = 1
+    }
+
+
+    @PublishedApi
+    internal inline var publishedVar: Int
+        get() {
+            publicFun()
+            internalFun()
+            privateFun()
+
+            publicVarTopLevel
+            publicVarTopLevel = 1
+            internalVarTopLevel
+            internalVarTopLevel = 1
+            privateVarTopLevel
+            privateVarTopLevel = 1
+            return 1
+        }
+
+        set(value) {
+            publicFun()
+            internalFun()
+            privateFun()
+
+            publicVarTopLevel
+            publicVarTopLevel = 1
+            internalVarTopLevel
+            internalVarTopLevel = 1
+            privateVarTopLevel
+            privateVarTopLevel = 1
+        }
+
+}
+
+@PublishedApi
+internal fun publishedTopLevel() {
+    publicFun()
+    internalFun()
+    privateFun()
+
+    publicVarTopLevel
+    publicVarTopLevel = 1
+    internalVarTopLevel
+    internalVarTopLevel = 1
+    privateVarTopLevel
+    privateVarTopLevel = 1
+}
+
+@PublishedApi
+inline internal fun publishedTopLevelInline() {
+    publicFun()
+    internalFun()
+    privateFun()
+
+    publicVarTopLevel
+    publicVarTopLevel = 1
+    internalVarTopLevel
+    internalVarTopLevel = 1
+    privateVarTopLevel
+    privateVarTopLevel = 1
+}
+
+@PublishedApi
+inline internal var publishedVarTopLevel: Int
+    get() {
+        publicFun()
+        internalFun()
+        privateFun()
+
+        publicVarTopLevel
+        publicVarTopLevel = 1
+        internalVarTopLevel
+        internalVarTopLevel = 1
+        privateVarTopLevel
+        privateVarTopLevel = 1
+        return 1
+    }
+
+    set(value) {
+        publicFun()
+        internalFun()
+        privateFun()
+
+        publicVarTopLevel
+        publicVarTopLevel = 1
+        internalVarTopLevel
+        internalVarTopLevel = 1
+        privateVarTopLevel
+        privateVarTopLevel = 1
+    }
+
+
+fun publicFun() {}
+
+internal fun internalFun() {}
+
+private fun privateFun() {}
+
+
+var publicVarTopLevel = 1
+
+internal var internalVarTopLevel = 1
+
+private var privateVarTopLevel = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/recursion.fir.kt b/compiler/testData/diagnostics/tests/inline/recursion.fir.kt
new file mode 100644
index 00000000000..905e848bcae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/recursion.fir.kt
@@ -0,0 +1,24 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -NOTHING_TO_INLINE -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -VARIABLE_EXPECTED
+
+inline fun inlineFun(s: (p: Int) -> Unit) {
+    inlineFun(s)
+}
+
+inline fun <T> inlineFun(s: T) {
+    inlineFun<Int>(11)
+}
+
+
+inline fun <T> Function0<T>.inlineExt() {
+    (checkSubtype<Function0<Int>>({11})).inlineExt();
+    {11}.inlineExt()
+}
+
+inline operator fun <T, V> Function1<T, V>.not() : Boolean {
+    return !this
+}
+
+inline operator fun <T, V> Function1<T, V>.inc() : Function1<T, V> {
+    return this++
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/regressions/kt4341.fir.kt b/compiler/testData/diagnostics/tests/inline/regressions/kt4341.fir.kt
new file mode 100644
index 00000000000..ed80d11bd1d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/regressions/kt4341.fir.kt
@@ -0,0 +1,6 @@
+//KT-4341 No resolved call for right-hand side of equals expression
+package g
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T) -> U) {
+    s == s //resolved call for right-hand side 's' not traced
+}
diff --git a/compiler/testData/diagnostics/tests/inline/returns.fir.kt b/compiler/testData/diagnostics/tests/inline/returns.fir.kt
new file mode 100644
index 00000000000..bdf8c0bd8a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/returns.fir.kt
@@ -0,0 +1,20 @@
+inline fun inlineFun(s: (p: Int) -> Unit) : (p: Int) -> Unit {
+    return s
+}
+
+inline fun inlineFun2(s: (p: Int) -> Unit) : (p: Int) -> Unit = s
+
+
+inline fun inlineFunWithExt(ext: Int.(p: Int) -> Unit) : Int.(p: Int) -> Unit {
+    return ext
+}
+
+inline fun inlineFunWithExt2(ext: Int.(p: Int) -> Unit) : Int.(p: Int) -> Unit = ext
+
+
+
+inline fun Function1<Int, Unit>.inlineExt(): Function1<Int, Unit> {
+    return this
+}
+
+inline fun Function1<Int, Unit>.inlineExt2(): Function1<Int, Unit> = this
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/sam.fir.kt b/compiler/testData/diagnostics/tests/inline/sam.fir.kt
new file mode 100644
index 00000000000..31c5e88ccf4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/sam.fir.kt
@@ -0,0 +1,58 @@
+// !DIAGNOSTICS: -NON_LOCAL_RETURN_NOT_ALLOWED
+// FILE: Run.java
+public interface Run {
+    public int run();
+}
+
+
+// FILE: Test.java
+public class Test {
+    public void test(Run r) {
+
+    }
+}
+
+// FILE: test.kt
+inline fun inlineFunWithInvoke(s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    Test().test(){
+        s(11)
+        s.invoke(11)
+        s invoke 11
+
+        11.<!UNRESOLVED_REFERENCE!>ext<!>(11)
+        11 <!UNRESOLVED_REFERENCE!>ext<!> 11
+
+        s
+        ext
+        11
+    }
+}
+
+inline fun inlineFunWithInvokeNonInline(noinline s: (p: Int) -> Unit, ext: Int.(p: Int) -> Unit) {
+    Test().test(){
+        s(11)
+        s.invoke(11)
+        s invoke 11
+
+        11.<!UNRESOLVED_REFERENCE!>ext<!>(11)
+        11 <!UNRESOLVED_REFERENCE!>ext<!> 11
+
+        s
+        ext
+
+        11
+    }
+}
+
+inline fun Function1<Int, Unit>.inlineExt() {
+    Test().test(){
+        invoke(11)
+        this.invoke(11)
+        this invoke 11
+        this(11)
+
+        this
+
+        11
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/stringTemplate.fir.kt b/compiler/testData/diagnostics/tests/inline/stringTemplate.fir.kt
new file mode 100644
index 00000000000..ae1c745c672
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/stringTemplate.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+inline public fun reg(converter: (Any) -> Any, str: String) {
+    str
+    converter("")
+}
+
+public inline fun register(converter: (Any) -> Any) {
+    "123$converter"
+    reg(converter, "123$converter")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/unaryExpressions/mathOperation.fir.kt b/compiler/testData/diagnostics/tests/inline/unaryExpressions/mathOperation.fir.kt
new file mode 100644
index 00000000000..36ef67bba28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/unaryExpressions/mathOperation.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -VAL_REASSIGNMENT -UNUSED_CHANGED_VALUE -VARIABLE_EXPECTED
+
+inline operator fun <T, V> Function1<T, V>.unaryPlus() = this
+operator fun <T, V> Function1<T, V>.unaryMinus() = this
+inline operator fun <T, V> Function1<T, V>.inc() = this
+operator fun <T, V> Function1<T, V>.dec() = this
+
+inline operator fun <T, V> @ExtensionFunctionType Function2<T, T, V>.unaryPlus(){}
+operator fun <T, V> @ExtensionFunctionType Function2<T, T, V>.unaryMinus(){}
+inline operator fun <T, V> @ExtensionFunctionType Function2<T, T, V>.inc() = this
+operator fun <T, V> @ExtensionFunctionType Function2<T, T, V>.dec() = this
+
+inline fun <T, V> inlineFunWithInvoke(s: (p: T) -> V, ext: T.(p: T) -> V) {
+    +s
+    -s
+    s++
+    ++s
+    s--
+    --s
+    +ext
+    -ext
+    ext++
+    ++ext
+    ext--
+    --ext
+}
+
+inline fun <T, V> Function1<T, V>.inlineFunWithInvoke() {
+    +this
+    -this
+    this++
+    ++this
+    this--
+    --this
+}
diff --git a/compiler/testData/diagnostics/tests/inline/unaryExpressions/notOnCall.fir.kt b/compiler/testData/diagnostics/tests/inline/unaryExpressions/notOnCall.fir.kt
new file mode 100644
index 00000000000..2a9f4cda4f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/unaryExpressions/notOnCall.fir.kt
@@ -0,0 +1,3 @@
+public inline fun test(predicate: (Char) -> Boolean) {
+    !predicate('c')
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/unaryExpressions/notOperation.fir.kt b/compiler/testData/diagnostics/tests/inline/unaryExpressions/notOperation.fir.kt
new file mode 100644
index 00000000000..864423fa3de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/unaryExpressions/notOperation.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -RECURSION_IN_INLINE
+inline operator fun <T, V> Function1<T, V>.not() : Boolean {
+    return !this
+}
+
+inline fun <T, V> inlineFunWithInvoke(s: (p: T) -> V) {
+    !s
+}
+
+operator fun <T, U, V> Function2<T, U, V>.not() : Boolean {
+    return !this
+}
+
+operator fun <T, U, V, W> @ExtensionFunctionType Function3<T, U, V, W>.not() : Boolean {
+    return !this
+}
+
+inline fun <T, U, V> inlineFunWithInvoke(s: (p: T, l: U) -> V, ext: T.(p: T, l : U) -> V) {
+    !s
+    !ext
+}
diff --git a/compiler/testData/diagnostics/tests/inline/unsupportedConstruction.fir.kt b/compiler/testData/diagnostics/tests/inline/unsupportedConstruction.fir.kt
new file mode 100644
index 00000000000..55269200a9a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/unsupportedConstruction.fir.kt
@@ -0,0 +1,33 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+// !LANGUAGE: -InlineDefaultFunctionalParameters
+
+inline fun unsupported() {
+
+    class A {
+        fun a() {
+           class AInner {}
+        }
+    }
+
+    object B{
+        object BInner {}
+    }
+
+    fun local() {
+        fun localInner() {}
+    }
+}
+
+inline fun unsupportedDefault(s : ()->Unit = {}) {
+
+}
+
+open class Base {
+    open fun foo(a: Int = 1) {}
+}
+
+class Derived: Base() {
+    inline final override fun foo(a: Int) {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/vararg.fir.kt b/compiler/testData/diagnostics/tests/inline/vararg.fir.kt
new file mode 100644
index 00000000000..305d27c98cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/vararg.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -NOTHING_TO_INLINE
+
+inline fun inlineFun(s: (p: Int) -> Unit, noinline b: (p: Int) -> Unit) {
+    subInline(s, b)
+    subNoInline(s, b)
+}
+
+inline fun Function1<Int, Unit>.inlineExt(s: (p: Int) -> Unit, noinline b: (p: Int) -> Unit) {
+    subInline(this, s, b)
+    subNoInline(this, s, b)
+}
+
+
+inline fun subInline(vararg s: (p: Int) -> Unit) {}
+
+fun subNoInline(vararg s: (p: Int) -> Unit) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/when.fir.kt b/compiler/testData/diagnostics/tests/inline/when.fir.kt
new file mode 100644
index 00000000000..9fb50407b45
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/when.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+inline public fun reg(converter: (Any) -> Any) {
+    converter("")
+}
+
+public inline fun register(converter: (Any) -> Any) {
+    reg(when(converter) {
+        is (Any) -> Any -> converter
+        else -> converter
+    })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inline/wrongUsage.fir.kt b/compiler/testData/diagnostics/tests/inline/wrongUsage.fir.kt
new file mode 100644
index 00000000000..c2ca220a4b9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inline/wrongUsage.fir.kt
@@ -0,0 +1,51 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -NOTHING_TO_INLINE -USELESS_ELVIS
+
+inline fun inlineFunWrongUsage(s: (p: Int) -> Unit) {
+    s
+
+    if (true) s else 0
+
+    s ?: s
+}
+
+inline fun inlineFunWrongUsageExt(ext: Int.(p: Int) -> Unit) {
+    ext
+
+    if (true) ext else 0
+
+    ext ?: ext
+}
+
+inline fun inlineFunWrongUsageInClosure(s: (p: Int) -> Unit) {
+    <!UNRESOLVED_REFERENCE!>{
+        s
+
+        if (true) s else 0
+
+        s ?: s
+    }()<!>
+}
+
+inline fun inlineFunWrongUsageInClosureExt(ext: Int.(p: Int) -> Unit) {
+    <!UNRESOLVED_REFERENCE!>{
+        ext
+
+        if (true) ext else 0
+
+        ext ?: ext
+    }()<!>
+}
+
+inline fun inlineFunNoInline(noinline s: (p: Int) -> Unit) {
+    s
+    if (true) s else 0
+
+    s ?: s
+}
+
+inline fun inlineFunNoInline(noinline ext: Int.(p: Int) -> Unit) {
+    ext
+    if (true) ext else 0
+
+    ext ?: ext
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/basicInlineClassDeclaration.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/basicInlineClassDeclaration.fir.kt
new file mode 100644
index 00000000000..fdb6b5bb420
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/basicInlineClassDeclaration.fir.kt
@@ -0,0 +1,8 @@
+// !LANGUAGE: +InlineClasses
+
+inline class Foo(val x: Int)
+
+inline interface InlineInterface
+inline annotation class InlineAnn
+inline object InlineObject
+inline enum class InlineEnum
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/basicInlineClassDeclarationDisabled.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/basicInlineClassDeclarationDisabled.fir.kt
new file mode 100644
index 00000000000..b3ddad1f098
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/basicInlineClassDeclarationDisabled.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: -InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline class Foo(val x: Int)
+
+inline annotation class InlineAnn
+inline object InlineObject
+inline enum class InlineEnum
+
+inline class NotVal(x: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/constructorsJvmSignaturesClash.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/constructorsJvmSignaturesClash.fir.kt
new file mode 100644
index 00000000000..c46969ca1e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/constructorsJvmSignaturesClash.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline class X(val x: Int)
+inline class Z(val x: Int)
+
+class TestOk1(val a: Int, val b: Int) {
+    constructor(x: X) : this(x.x, 1)
+}
+
+class TestErr1(val a: Int) {
+    constructor(x: X) : this(x.x)
+}
+
+class TestErr2(val a: Int, val b: Int) {
+    constructor(x: X) : this(x.x, 1)
+    constructor(z: Z) : this(z.x, 2)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/delegatedPropertyInInlineClass.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/delegatedPropertyInInlineClass.fir.kt
new file mode 100644
index 00000000000..77dd8988c78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/delegatedPropertyInInlineClass.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +InlineClasses
+
+class Val {
+    operator fun getValue(thisRef: Any?, kProp: Any?) = 1
+}
+
+class Var {
+    operator fun getValue(thisRef: Any?, kProp: Any?) = 2
+    operator fun setValue(thisRef: Any?, kProp: Any?, value: Int) {}
+}
+
+
+object ValObject {
+    operator fun getValue(thisRef: Any?, kProp: Any?) = 1
+}
+
+object VarObject {
+    operator fun getValue(thisRef: Any?, kProp: Any?) = 2
+    operator fun setValue(thisRef: Any?, kProp: Any?, value: Int) {}
+}
+
+inline class Z(val data: Int) {
+    val testVal by Val()
+    var testVar by Var()
+
+    val testValBySingleton by ValObject
+    var testVarBySingleton by VarObject
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/functionsJvmSignaturesClash.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/functionsJvmSignaturesClash.fir.kt
new file mode 100644
index 00000000000..2269b291aaf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/functionsJvmSignaturesClash.fir.kt
@@ -0,0 +1,37 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline class X(val x: Int)
+inline class Z(val x: Int)
+inline class Str(val str: String)
+inline class Name(val name: String)
+inline class NStr(val str: String?)
+
+fun testSimple(x: X) {}
+fun testSimple(z: Z) {}
+
+fun testMixed(x: Int, y: Int) {}
+fun testMixed(x: X, y: Int) {}
+fun testMixed(x: Int, y: X) {}
+fun testMixed(x: X, y: X) {}
+
+fun testNewType(s: Str) {}
+fun testNewType(name: Name) {}
+
+fun testNullableVsNonNull1(s: Str) {}
+fun testNullableVsNonNull1(s: Str?) {}
+
+fun testNullableVsNonNull2(ns: NStr) {}
+fun testNullableVsNonNull2(ns: NStr?) {}
+
+fun testFunVsExt(x: X) {}
+fun X.testFunVsExt() {}
+
+fun testNonGenericVsGeneric(x: X, y: Number) {}
+fun <T : Number> testNonGenericVsGeneric(x: X, y: T) {}
+
+class C<TC : Number> {
+    fun testNonGenericVsGeneric(x: X, y: Number) {}
+    fun <T : Number> testNonGenericVsGeneric(x: X, y: T) {}
+    fun testNonGenericVsGeneric(x: X, y: TC) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/functionsJvmSignaturesConflictOnInheritance.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/functionsJvmSignaturesConflictOnInheritance.fir.kt
new file mode 100644
index 00000000000..4d71d826e72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/functionsJvmSignaturesConflictOnInheritance.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +InlineClasses
+
+inline class Name(val name: String)
+inline class Password(val password: String)
+
+interface NameVerifier {
+    fun verify(name: Name)
+}
+
+interface PasswordVerifier {
+    fun verify(password: Password)
+}
+
+interface NameAndPasswordVerifier : NameVerifier, PasswordVerifier
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/identityComparisonWithInlineClasses.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/identityComparisonWithInlineClasses.fir.kt
new file mode 100644
index 00000000000..b4e920e64a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/identityComparisonWithInlineClasses.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline class Foo(val x: Int)
+inline class Bar(val y: String)
+
+fun test(f1: Foo, f2: Foo, b1: Bar, fn1: Foo?, fn2: Foo?) {
+    val a1 = f1 === f2 || f1 !== f2
+    val a2 = f1 === f1
+    val a3 = f1 === b1 || f1 !== b1
+
+    val c1 = fn1 === fn2 || fn1 !== fn2
+    val c2 = f1 === fn1 || f1 !== fn1
+    val c3 = b1 === fn1 || b1 !== fn1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/inlineClassCanOnlyImplementInterfaces.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassCanOnlyImplementInterfaces.fir.kt
new file mode 100644
index 00000000000..07970c657c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassCanOnlyImplementInterfaces.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +InlineClasses
+
+abstract class AbstractBaseClass
+
+open class OpenBaseClass
+
+interface BaseInterface
+
+inline class TestExtendsAbstractClass(val x: Int) : AbstractBaseClass()
+
+inline class TestExtendsOpenClass(val x: Int) : OpenBaseClass()
+
+inline class TestImplementsInterface(val x: Int) : BaseInterface
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/inlineClassCannotImplementInterfaceByDelegation.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassCannotImplementInterfaceByDelegation.fir.kt
new file mode 100644
index 00000000000..fc15d5e7721
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassCannotImplementInterfaceByDelegation.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +InlineClasses
+
+interface IFoo
+
+object FooImpl : IFoo
+
+inline class Test1(val x: Any) : IFoo by FooImpl
+
+inline class Test2(val x: IFoo) : IFoo by x
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/inlineClassConstructorParameterWithDefaultValue.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassConstructorParameterWithDefaultValue.fir.kt
new file mode 100644
index 00000000000..14efbfee879
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassConstructorParameterWithDefaultValue.fir.kt
@@ -0,0 +1,3 @@
+// !LANGUAGE: +InlineClasses
+
+inline class Test(val x: Int = 42)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/inlineClassDeclarationCheck.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassDeclarationCheck.fir.kt
new file mode 100644
index 00000000000..1dc1d59e16d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassDeclarationCheck.fir.kt
@@ -0,0 +1,33 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline class A0(val x: Int)
+
+inline class A1
+inline class A2()
+inline class A3(x: Int)
+inline class A4(var x: Int)
+inline class A5(val x: Int, val y: Int)
+inline class A6(x: Int, val y: Int)
+inline class A7(vararg val x: Int)
+inline class A8(open val x: Int)
+inline class A9(final val x: Int)
+
+class B1 {
+    companion object {
+        inline class C1(val x: Int)
+    }
+
+    inline class C2(val x: Int)
+}
+
+object B2 {
+    inline class C3(val x: Int)
+}
+
+final inline class D0(val x: Int)
+open inline class D1(val x: Int)
+abstract inline class D2(val x: Int)
+sealed inline class D3(val x: Int)
+
+inline data class D4(val x: String)
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/inlineClassImplementsCollection.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassImplementsCollection.fir.kt
new file mode 100644
index 00000000000..b665afb1e14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassImplementsCollection.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +InlineClasses
+
+inline class UInt(val x: Int)
+
+inline class UIntArray(private val storage: IntArray) : Collection<UInt> {
+    public override val size: Int get() = storage.size
+
+    override operator fun iterator() = TODO()
+    override fun contains(element: UInt): Boolean = TODO()
+    override fun containsAll(elements: Collection<UInt>): Boolean = TODO()
+    override fun isEmpty(): Boolean = TODO()
+}
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/inlineClassWithForbiddenUnderlyingType.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassWithForbiddenUnderlyingType.fir.kt
new file mode 100644
index 00000000000..650bcb0e190
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassWithForbiddenUnderlyingType.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +InlineClasses
+
+inline class Foo<T>(val x: T)
+inline class FooNullable<T>(val x: T?)
+
+inline class FooGenericArray<T>(val x: Array<T>)
+inline class FooGenericArray2<T>(val x: Array<Array<T>>)
+
+inline class FooStarProjectedArray(val x: Array<*>)
+inline class FooStarProjectedArray2(val x: Array<Array<*>>)
+
+inline class Bar(val u: Unit)
+inline class BarNullable(val u: Unit?)
+
+inline class Baz(val u: Nothing)
+inline class BazNullable(val u: Nothing?)
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/inlineClassesInsideAnnotations.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassesInsideAnnotations.fir.kt
new file mode 100644
index 00000000000..861f728fed8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/inlineClassesInsideAnnotations.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +InlineClasses
+
+import kotlin.reflect.KClass
+
+inline class MyInt(val x: Int)
+inline class MyString(val x: String)
+
+annotation class Ann1(val a: MyInt)
+annotation class Ann2(val a: Array<MyString>)
+annotation class Ann3(vararg val a: MyInt)
+
+annotation class Ann4(val a: KClass<MyInt>)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/lateinitInlineClasses.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/lateinitInlineClasses.fir.kt
new file mode 100644
index 00000000000..d81f5b2b0e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/lateinitInlineClasses.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline class Foo(val x: Int)
+
+lateinit var a: Foo
+
+fun foo() {
+    lateinit var b: Foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/presenceOfInitializerBlockInsideInlineClass.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/presenceOfInitializerBlockInsideInlineClass.fir.kt
new file mode 100644
index 00000000000..338b20f53b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/presenceOfInitializerBlockInsideInlineClass.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline class Foo(val x: Int) {
+    init {}
+
+    init {
+        val f = 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/presenceOfPublicPrimaryConstructorForInlineClass.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/presenceOfPublicPrimaryConstructorForInlineClass.fir.kt
new file mode 100644
index 00000000000..3d4387b1ec7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/presenceOfPublicPrimaryConstructorForInlineClass.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: +InlineClasses
+
+inline class ConstructorWithDefaultVisibility(val x: Int)
+inline class PublicConstructor public constructor(val x: Int)
+inline class InternalConstructor internal constructor(val x: Int)
+inline class ProtectedConstructor protected constructor(val x: Int)
+inline class PrivateConstructor private constructor(val x: Int)
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/propertiesWithBackingFieldsInsideInlineClass.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/propertiesWithBackingFieldsInsideInlineClass.fir.kt
new file mode 100644
index 00000000000..673b7ba8262
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/propertiesWithBackingFieldsInsideInlineClass.fir.kt
@@ -0,0 +1,34 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface A {
+    val goodSize: Int
+}
+
+interface B {
+    val badSize: Int
+}
+
+inline class Foo(val x: Int) : A, B {
+    val a0
+        get() = 0
+
+    val a1 = 0
+
+    var a2: Int
+        get() = 1
+        set(value) {}
+
+    var a3: Int = 0
+        get() = 1
+        set(value) {
+            field = value
+        }
+
+    override val goodSize: Int
+        get() = 0
+
+    override val badSize: Int = 0
+
+    lateinit var lateinitProperty: String
+}
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/recursiveInlineClasses.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/recursiveInlineClasses.fir.kt
new file mode 100644
index 00000000000..6ebf4f85568
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/recursiveInlineClasses.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +InlineClasses
+
+inline class Test1(val x: Test1)
+
+inline class Test2A(val x: Test2B)
+inline class Test2B(val x: Test2A)
+
+inline class Test3A(val x: Test3B)
+inline class Test3B(val x: Test3C)
+inline class Test3C(val x: Test3A)
+
+inline class TestNullable(val x: TestNullable?)
+
+inline class TestRecursionInTypeArguments(val x: List<TestRecursionInTypeArguments>)
+
+inline class TestRecursionInArray(val x: Array<TestRecursionInArray>)
+
+inline class TestRecursionInUpperBounds<T : TestRecursionInUpperBounds<T>>(val x: T)
+
+inline class Id<T>(val x: T)
+inline class TestRecursionThroughId(val x: Id<TestRecursionThroughId>)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/reservedMembersAndConstructsInsideInlineClass.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/reservedMembersAndConstructsInsideInlineClass.fir.kt
new file mode 100644
index 00000000000..c433e12c85f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/reservedMembersAndConstructsInsideInlineClass.fir.kt
@@ -0,0 +1,45 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline class IC1(val x: Any) {
+    fun box() {}
+    fun box(x: Any) {}
+
+    fun unbox() {}
+    fun unbox(x: Any) {}
+
+    override fun equals(other: Any?): Boolean = true
+    override fun hashCode(): Int = 0
+}
+
+inline class IC2(val x: Any) {
+    fun box(x: Any) {}
+    fun box(): Any = TODO()
+
+    fun unbox(x: Any) {}
+    fun unbox(): Any = TODO()
+
+    fun equals(my: Any, other: Any): Boolean = true
+    fun hashCode(a: Any): Int = 0
+}
+
+inline class IC3(val x: Any) {
+    fun box(x: Any): Any = TODO()
+    fun unbox(x: Any): Any = TODO()
+
+    fun equals(): Boolean = true
+}
+
+interface WithBox {
+    fun box(): String
+}
+
+inline class IC4(val s: String) : WithBox {
+    override fun box(): String = ""
+}
+
+inline class IC5(val a: String) {
+    constructor(i: Int) : this(i.toString()) {
+        TODO("something")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/unsignedLiteralsWithoutArtifactOnClasspath.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/unsignedLiteralsWithoutArtifactOnClasspath.fir.kt
new file mode 100644
index 00000000000..7fa08d2d9a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/unsignedLiteralsWithoutArtifactOnClasspath.fir.kt
@@ -0,0 +1,3 @@
+val u1 = 1u
+val u2 = 0xFu
+val u3 = 0b1u
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inlineClasses/varargsOnParametersOfInlineClassType.fir.kt b/compiler/testData/diagnostics/tests/inlineClasses/varargsOnParametersOfInlineClassType.fir.kt
new file mode 100644
index 00000000000..69737965c97
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inlineClasses/varargsOnParametersOfInlineClassType.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -UNUSED_ANONYMOUS_PARAMETER
+
+inline class Foo(val x: Int)
+
+fun f1(vararg a: Foo) {}
+fun f2(vararg a: Foo?) {}
+
+class A {
+    fun f3(a0: Int, vararg a1: Foo) {
+        fun f4(vararg a: Foo) {}
+
+        val g = fun (vararg v: Foo) {}
+    }
+}
+
+class B(vararg val s: Foo) {
+    constructor(a: Int, vararg s: Foo) : this(*s)
+}
+
+annotation class Ann(vararg val f: Foo)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/InnerClassNameClash.fir.kt b/compiler/testData/diagnostics/tests/inner/InnerClassNameClash.fir.kt
new file mode 100644
index 00000000000..9e9d3cf80ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/InnerClassNameClash.fir.kt
@@ -0,0 +1,10 @@
+package test
+
+class B {
+    class B {
+      fun foo(b: B.C) {
+      }
+      class C {
+      }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/accessingToJavaNestedClass.fir.kt b/compiler/testData/diagnostics/tests/inner/accessingToJavaNestedClass.fir.kt
new file mode 100644
index 00000000000..efd4caaf9b0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/accessingToJavaNestedClass.fir.kt
@@ -0,0 +1,64 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// FILE: A.java
+
+public class A {
+    static class NC {}
+    class IC {}
+    static interface NI {}
+}
+
+// FILE: I.java
+
+public interface I {
+    class NC {}
+    interface NI {}
+}
+
+// FILE: B.java
+
+public class B extends A {
+
+}
+
+// FILE: C.java
+
+public class C implements I {
+
+}
+
+// FILE: D.java
+
+public class D extends A implements I {
+
+}
+
+// FILE: K.kt
+
+class K : D()
+
+// FILE: test.kt
+
+fun test() {
+    val ac: A.NC = A.NC()
+    val aic: A.IC = A().IC()
+    val ai: A.NI? = null
+
+    val ic: I.NC = I.NC()
+    val ii: I.NI? = null
+
+    val bc: B.NC = B.NC()
+    val bic: B.IC = B().IC()
+    val bi: B.NI? = null
+
+    val cc: C.NC = C.NC()
+    val ci: C.NI? = null
+
+    val dc: D.NC = D.NC()
+    val dic: D.IC = D().IC()
+    val di: D.NI? = null
+
+    val kc: K.NC = K.NC()
+    val kic: K.IC = K().IC()
+    val ki: K.NI? = null
+}
diff --git a/compiler/testData/diagnostics/tests/inner/accessingToKotlinNestedClass.fir.kt b/compiler/testData/diagnostics/tests/inner/accessingToKotlinNestedClass.fir.kt
new file mode 100644
index 00000000000..f5dc4fdaad1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/accessingToKotlinNestedClass.fir.kt
@@ -0,0 +1,44 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+open class A {
+    class NC {}
+    inner class IC {}
+    interface NI {}
+}
+
+interface I {
+    class NC {}
+    interface NI {}
+}
+
+class B : A() {
+
+}
+
+class C : I {
+
+}
+
+class D : A(), I {
+
+}
+
+fun test() {
+    val ac: A.NC = A.NC()
+    val aic: A.IC = A().IC()
+    val ai: A.NI? = null
+
+    val ic: I.NC = I.NC()
+    val ii: I.NI? = null
+
+    val bc: B.NC = B.NC()
+    val bic: B.IC = B().IC()
+    val bi: B.NI? = null
+
+    val cc: C.NC = C.NC()
+    val ci: C.NI? = null
+
+    val dc: D.NC = D.NC()
+    val dic: D.IC = D().IC()
+    val di: D.NI? = null
+}
diff --git a/compiler/testData/diagnostics/tests/inner/annotationInInnerClass.fir.kt b/compiler/testData/diagnostics/tests/inner/annotationInInnerClass.fir.kt
new file mode 100644
index 00000000000..903b7c13869
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/annotationInInnerClass.fir.kt
@@ -0,0 +1,5 @@
+class Outer {
+    inner class Inner {
+        annotation class TestNestedAnnotation
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/classesInClassObjectHeader.fir.kt b/compiler/testData/diagnostics/tests/inner/classesInClassObjectHeader.fir.kt
new file mode 100644
index 00000000000..b1e7bc807dd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/classesInClassObjectHeader.fir.kt
@@ -0,0 +1,11 @@
+class Test {
+    @`InnerAnnotation` @InnerAnnotation
+    companion object : StaticClass(), InnerClass() {
+
+    }
+
+    annotation class InnerAnnotation
+    open class StaticClass
+
+    open inner class InnerClass
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/constructorAccess.fir.kt b/compiler/testData/diagnostics/tests/inner/constructorAccess.fir.kt
new file mode 100644
index 00000000000..959b9a6d0b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/constructorAccess.fir.kt
@@ -0,0 +1,32 @@
+class Outer1 {
+    class Nested
+
+    class C1 { val b = Nested() }
+    class C2(val b: Any = Nested())
+    inner class C3 { val b = Nested() }
+    inner class C4(val b: Any = Nested())
+
+    inner class Inner
+
+    class C5 { val b = Inner() }
+    class C6(val b: Any = Inner())
+    inner class C7 { val b = Inner() }
+    inner class C8(val b: Any = Inner())
+}
+
+
+class Outer2 {
+    class Nested {
+        fun foo() = Outer2()
+        fun bar() = Inner()
+    }
+    inner class Inner {
+        fun foo() = Outer2()
+        fun bar() = Nested()
+    }
+
+    fun foo() {
+        Nested()
+        Inner()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/deepInnerClass.fir.kt b/compiler/testData/diagnostics/tests/inner/deepInnerClass.fir.kt
new file mode 100644
index 00000000000..2431bd87d21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/deepInnerClass.fir.kt
@@ -0,0 +1,14 @@
+interface P<U, Y>
+
+class A<T> {
+    class B {
+        fun test() {
+            class C<W>() : P<W, T> {
+                companion object : P<W, T> {
+                }
+
+                inner class D : P<W, T>
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/enumEntries.fir.kt b/compiler/testData/diagnostics/tests/inner/enumEntries.fir.kt
new file mode 100644
index 00000000000..dad79e88daa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/enumEntries.fir.kt
@@ -0,0 +1,12 @@
+enum class E {
+    E1 {
+        override fun foo() = <!UNRESOLVED_REFERENCE!>outerFun<!>() + super.<!UNRESOLVED_REFERENCE!>outerFun<!>()
+    },
+    E2 {
+        override fun foo() = E1.foo()
+    };
+    
+    abstract fun foo(): Int
+    
+    fun outerFun() = 42
+}
diff --git a/compiler/testData/diagnostics/tests/inner/enumInInnerClass.fir.kt b/compiler/testData/diagnostics/tests/inner/enumInInnerClass.fir.kt
new file mode 100644
index 00000000000..8ca09096ec6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/enumInInnerClass.fir.kt
@@ -0,0 +1,5 @@
+class Outer {
+    inner class Inner {
+        enum class TestNestedEnum
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/extensionFun.fir.kt b/compiler/testData/diagnostics/tests/inner/extensionFun.fir.kt
new file mode 100644
index 00000000000..f43b8b80566
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/extensionFun.fir.kt
@@ -0,0 +1,28 @@
+class Outer {
+    class Nested
+    inner class Inner
+    
+    fun Inner.foo() {
+        Outer()
+        Nested()
+        Inner()
+    }
+    
+    fun Nested.bar() {
+        Outer()
+        Nested()
+        Inner()
+    }
+    
+    fun Outer.baz() {
+        Outer()
+        Nested()
+        Inner()
+    }
+}
+
+fun Outer.foo() {
+    Outer()
+    Nested()
+    Inner()
+}
diff --git a/compiler/testData/diagnostics/tests/inner/extensionLambdaInsideNestedClass.fir.kt b/compiler/testData/diagnostics/tests/inner/extensionLambdaInsideNestedClass.fir.kt
new file mode 100644
index 00000000000..0c6e0e544ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/extensionLambdaInsideNestedClass.fir.kt
@@ -0,0 +1,27 @@
+package f
+
+object A {
+    class LoginFormPage() : Request({
+        val failed = <!UNRESOLVED_REFERENCE!>session<!>.<!UNRESOLVED_REFERENCE!>get<!>("LOGIN_FAILED")
+    })
+}
+
+class B {
+    companion object {
+        class LoginFormPage() : Request({
+            val failed = <!UNRESOLVED_REFERENCE!>session<!>.<!UNRESOLVED_REFERENCE!>get<!>("LOGIN_FAILED")
+        })
+    }
+
+    class C {
+        class LoginFormPage() : Request({
+            val failed = <!UNRESOLVED_REFERENCE!>session<!>.<!UNRESOLVED_REFERENCE!>get<!>("LOGIN_FAILED")
+        })
+    }
+}
+
+open class Request(private val handler: ActionContext.() -> Unit) {}
+
+interface ActionContext {
+    val session : Map<String, String>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/illegalModifier.fir.kt b/compiler/testData/diagnostics/tests/inner/illegalModifier.fir.kt
new file mode 100644
index 00000000000..28c8691442c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/illegalModifier.fir.kt
@@ -0,0 +1,45 @@
+// !LANGUAGE: -InnerClassInEnumEntryClass
+inner fun foo() {}
+inner val prop = 42
+
+inner class A
+inner interface B
+inner object C
+
+class D {
+    inner class E
+    inner interface F
+    inner object G
+    inner enum class R
+    inner annotation class S
+    inner companion object
+}
+
+enum class H {
+    I0 {
+        inner class II0
+    },
+    inner I {
+        inner class II
+    };
+    
+    inner class J
+}
+
+interface K {
+    inner class L
+}
+
+object N {
+    inner class O
+}
+
+class P {
+    companion object {
+        inner class Q
+    }
+}
+
+val R = object {
+    inner class S
+}
diff --git a/compiler/testData/diagnostics/tests/inner/illegalModifier_lv12.fir.kt b/compiler/testData/diagnostics/tests/inner/illegalModifier_lv12.fir.kt
new file mode 100644
index 00000000000..ddc9f30edbd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/illegalModifier_lv12.fir.kt
@@ -0,0 +1,45 @@
+// !LANGUAGE: +InnerClassInEnumEntryClass
+inner fun foo() {}
+inner val prop = 42
+
+inner class A
+inner interface B
+inner object C
+
+class D {
+    inner class E
+    inner interface F
+    inner object G
+    inner enum class R
+    inner annotation class S
+    inner companion object
+}
+
+enum class H {
+    I0 {
+        inner class II0
+    },
+    inner I {
+        inner class II
+    };
+    
+    inner class J
+}
+
+interface K {
+    inner class L
+}
+
+object N {
+    inner class O
+}
+
+class P {
+    companion object {
+        inner class Q
+    }
+}
+
+val R = object {
+    inner class S
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClassMemberResolve.fir.kt b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClassMemberResolve.fir.kt
new file mode 100644
index 00000000000..36aca591b84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClassMemberResolve.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +InnerClassInEnumEntryClass
+
+enum class A {
+    X {
+        val x = 1
+        fun foo() {}
+
+        inner class Inner {
+            val y = x
+            fun bar() = foo()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv11.fir.kt b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv11.fir.kt
new file mode 100644
index 00000000000..6391c59d91b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv11.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: -InnerClassInEnumEntryClass -NestedClassesInEnumEntryShouldBeInner
+
+enum class Enum {
+    ENTRY_WITH_CLASS {
+        inner class TestInner
+
+        class TestNested
+
+        interface TestInterface
+
+        object TestObject
+
+        enum class TestEnumClass {
+            OTHER_ENTRY
+        }
+
+        companion object {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv12.fir.kt b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv12.fir.kt
new file mode 100644
index 00000000000..ba98e4a6478
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv12.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +InnerClassInEnumEntryClass -NestedClassesInEnumEntryShouldBeInner
+
+enum class Enum {
+    ENTRY_WITH_CLASS {
+        inner class TestInner
+
+        class TestNested
+
+        interface TestInterface
+
+        object TestObject
+
+        enum class TestEnumClass {
+            OTHER_ENTRY
+        }
+
+        companion object {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv13.fir.kt b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv13.fir.kt
new file mode 100644
index 00000000000..2f2869d3a40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerClassInEnumEntryClass_lv13.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +InnerClassInEnumEntryClass +NestedClassesInEnumEntryShouldBeInner
+
+enum class Enum {
+    ENTRY_WITH_CLASS {
+        inner class TestInner
+
+        class TestNested
+
+        interface TestInterface
+
+        object TestObject
+
+        enum class TestEnumClass {
+            OTHER_ENTRY
+        }
+
+        companion object {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerClassesInStaticParameters.fir.kt b/compiler/testData/diagnostics/tests/inner/innerClassesInStaticParameters.fir.kt
new file mode 100644
index 00000000000..c4f1408564d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerClassesInStaticParameters.fir.kt
@@ -0,0 +1,11 @@
+class Test {
+    companion object {
+        fun test(t: TestInner) = 42
+    }
+
+    class TestStatic {
+        fun test(t: TestInner) = 42
+    }
+
+    inner class TestInner
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/innerConstructorsFromQualifiers.fir.kt b/compiler/testData/diagnostics/tests/inner/innerConstructorsFromQualifiers.fir.kt
new file mode 100644
index 00000000000..4c3dce517eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerConstructorsFromQualifiers.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+// FILE: Outer.kt
+package abc
+class Outer {
+    inner class Inner() {
+        constructor(x: Int) : this() {}
+    }
+
+    companion object {
+
+        fun baz() {
+            Inner()
+            Inner(1)
+        }
+    }
+}
+
+fun foo() {
+    Outer.<!UNRESOLVED_REFERENCE!>Inner<!>()
+    Outer.<!UNRESOLVED_REFERENCE!>Inner<!>(1)
+}
+
+// FILE: imported.kt
+import abc.Outer
+import abc.Outer.Inner
+
+fun bar() {
+    Inner()
+    Inner(1)
+
+    with(Outer()) {
+        Inner()
+        Inner(1)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/innerConstructorsFromQualifiersWithIrrelevantCandidate.fir.kt b/compiler/testData/diagnostics/tests/inner/innerConstructorsFromQualifiersWithIrrelevantCandidate.fir.kt
new file mode 100644
index 00000000000..303bb5a88dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerConstructorsFromQualifiersWithIrrelevantCandidate.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+// FILE: Outer.kt
+package abc
+class Outer {
+    inner class Inner() {
+        constructor(x: Int) : this() {}
+    }
+
+    companion object {
+        fun Inner(x: String) {}
+
+        fun baz() {
+            // Diagnostic here could be better (why can't I call the constructor above?)
+            Inner()
+            Inner(1)
+            Inner("")
+        }
+    }
+}
+
+fun foo() {
+    Outer.<!INAPPLICABLE_CANDIDATE!>Inner<!>()
+    Outer.<!INAPPLICABLE_CANDIDATE!>Inner<!>(1)
+    Outer.Inner("")
+}
+
+// FILE: imported.kt
+import abc.Outer
+import abc.Outer.Inner
+import abc.Outer.Companion.Inner
+
+fun bar() {
+    Inner()
+    Inner(1)
+    Inner("")
+
+    with(Outer()) {
+        Inner()
+        Inner(1)
+        Inner("")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerErrorForClassObjects.fir.kt b/compiler/testData/diagnostics/tests/inner/innerErrorForClassObjects.fir.kt
new file mode 100644
index 00000000000..f91ff272ef0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerErrorForClassObjects.fir.kt
@@ -0,0 +1,26 @@
+open class SomeClass<T>
+class TestSome<P> {
+    companion object : SomeClass<P>() {
+    }
+}
+
+class Test {
+    companion object : InnerClass() {
+        val a = object: InnerClass() {
+        }
+
+        fun more(): InnerClass {
+            val b = InnerClass()
+
+            val testVal = <!UNRESOLVED_REFERENCE!>inClass<!>
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+
+            return b
+        }
+    }
+
+    val inClass = 12
+    fun foo() {}
+
+    open inner class InnerClass
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerErrorForObjects.fir.kt b/compiler/testData/diagnostics/tests/inner/innerErrorForObjects.fir.kt
new file mode 100644
index 00000000000..0e447b286f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerErrorForObjects.fir.kt
@@ -0,0 +1,27 @@
+open class SomeClass<T>
+class TestSome<P> {
+    object Some : SomeClass<P>() {
+    }
+}
+
+class Test {
+    object Some : InnerClass() {
+        val a = object: InnerClass() {
+        }
+
+        fun more(): InnerClass {
+            val b = InnerClass()
+
+            val testVal = <!UNRESOLVED_REFERENCE!>inClass<!>
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+
+            return b
+        }
+    }
+
+    val inClass = 12
+    fun foo() {
+    }
+
+    open inner class InnerClass
+}
diff --git a/compiler/testData/diagnostics/tests/inner/innerThisSuper.fir.kt b/compiler/testData/diagnostics/tests/inner/innerThisSuper.fir.kt
new file mode 100644
index 00000000000..f6902c9ecda
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/innerThisSuper.fir.kt
@@ -0,0 +1,22 @@
+// NI_EXPECTED_FILE
+
+interface Trait {
+    fun bar() = 42
+}
+
+class Outer : Trait {
+    class Nested {
+        val t = this@Outer.bar()
+        val s = super@Outer.<!UNRESOLVED_REFERENCE!>bar<!>()
+        
+        inner class NestedInner {
+            val t = this@Outer.bar()
+            val s = super@Outer.<!UNRESOLVED_REFERENCE!>bar<!>()
+        }
+    }
+    
+    inner class Inner {
+        val t = this@Outer.bar()
+        val s = super@Outer.<!UNRESOLVED_REFERENCE!>bar<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/interfaceInInnerClass.fir.kt b/compiler/testData/diagnostics/tests/inner/interfaceInInnerClass.fir.kt
new file mode 100644
index 00000000000..a93f9f4155a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/interfaceInInnerClass.fir.kt
@@ -0,0 +1,5 @@
+class Outer {
+    inner class Inner {
+        interface TestNestedInterface
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/kt5854.fir.kt b/compiler/testData/diagnostics/tests/inner/kt5854.fir.kt
new file mode 100644
index 00000000000..ae458b800a5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/kt5854.fir.kt
@@ -0,0 +1,11 @@
+//KT-5854 Incorrect 'Nested class should be qualified'
+
+class A {
+    class Nested {
+
+    }
+
+    fun foo() {
+        <!INAPPLICABLE_CANDIDATE!>Nested<!>(1) //two errors here, the first one is wrong
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/kt6026.fir.kt b/compiler/testData/diagnostics/tests/inner/kt6026.fir.kt
new file mode 100644
index 00000000000..6a923f74e91
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/kt6026.fir.kt
@@ -0,0 +1,8 @@
+// KT-6026 Exception on instantiating a nested class in an anonymous object
+
+val oo = object {
+    // Forbidden in KT-13510
+    class Nested
+
+    fun f1() = <!UNRESOLVED_REFERENCE!>Nested<!>(11)
+}
diff --git a/compiler/testData/diagnostics/tests/inner/localClass.fir.kt b/compiler/testData/diagnostics/tests/inner/localClass.fir.kt
new file mode 100644
index 00000000000..0745bfff026
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/localClass.fir.kt
@@ -0,0 +1,18 @@
+class Outer {
+    fun foo(): Int {
+        if (outerState > 0) return outerState
+        
+        class Local {
+            val localState = <!UNRESOLVED_REFERENCE!>outerState<!>
+            
+            inner class LocalInner {
+                val o = <!UNRESOLVED_REFERENCE!>outerState<!>
+                val l = localState
+            }
+        }
+        
+        return Local().localState
+    }
+    
+    val outerState = 42
+}
diff --git a/compiler/testData/diagnostics/tests/inner/localClassInsideNested.fir.kt b/compiler/testData/diagnostics/tests/inner/localClassInsideNested.fir.kt
new file mode 100644
index 00000000000..a7eefec3262
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/localClassInsideNested.fir.kt
@@ -0,0 +1,11 @@
+class Outer {
+    class Nested {
+        fun foo() {
+            class Local {
+                val state = <!UNRESOLVED_REFERENCE!>outerState<!>
+            }
+        }
+    }
+    
+    val outerState = 42
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/localThisSuper.fir.kt b/compiler/testData/diagnostics/tests/inner/localThisSuper.fir.kt
new file mode 100644
index 00000000000..78c356415f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/localThisSuper.fir.kt
@@ -0,0 +1,23 @@
+interface Trait {
+    fun bar() = 42
+}
+
+class Outer : Trait {
+    fun foo() {
+        val t = this@Outer
+        val s = super@Outer.bar()
+        
+        class Local : Trait {
+            val t = this@Outer
+            val s = super@Outer.bar()
+            
+            inner class Inner {
+                val t = this@Local
+                val s = super@Local.<!UNRESOLVED_REFERENCE!>bar<!>()
+                
+                val tt = this@Outer
+                val ss = super@Outer.<!UNRESOLVED_REFERENCE!>bar<!>()
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/modality.fir.kt b/compiler/testData/diagnostics/tests/inner/modality.fir.kt
new file mode 100644
index 00000000000..461687e2b8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/modality.fir.kt
@@ -0,0 +1,17 @@
+class Outer {
+    open class OpenNested
+    class FinalNested
+    
+    open inner class OpenInner
+    class FinalInner
+
+    class Nested1 : OpenNested()
+    class Nested2 : FinalNested()
+    class Nested3 : OpenInner()
+    class Nested4 : FinalInner()
+
+    inner class Inner1 : OpenNested()
+    inner class Inner2 : FinalNested()
+    inner class Inner3 : OpenInner()
+    inner class Inner4 : FinalInner()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/nestedClassAccessedViaInstanceReference.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedClassAccessedViaInstanceReference.fir.kt
new file mode 100644
index 00000000000..72a896dde77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedClassAccessedViaInstanceReference.fir.kt
@@ -0,0 +1,53 @@
+interface N { fun foo() = 1 }
+
+class WithClassObject {
+    companion object {}
+
+    class Nested()
+    class NestedWithClassObject { companion object : N }
+    enum class NestedEnum { A }
+    object NestedObj : N { operator fun invoke() = 1 }
+}
+
+class WithoutClassObject {
+    class Nested()
+    class NestedWithClassObject { companion object : N }
+    enum class NestedEnum { A }
+    object NestedObj : N { operator fun invoke() = 1 }
+}
+
+object Obj {
+    class Nested()
+    class NestedWithClassObject { companion object : N }
+    enum class NestedEnum { A }
+    object NestedObj : N { operator fun invoke() = 1 }
+}
+
+fun test(with: WithClassObject, without: WithoutClassObject, obj: Obj) {
+    with.Nested()
+    with.NestedWithClassObject
+    with.NestedWithClassObject()
+    with.NestedWithClassObject.foo()
+    with.NestedEnum.A
+    with.NestedObj
+    with.<!INAPPLICABLE_CANDIDATE!>NestedObj<!>()
+    with.NestedObj.foo()
+
+    without.Nested()
+    without.NestedWithClassObject
+    without.NestedWithClassObject()
+    without.NestedWithClassObject.foo()
+    without.NestedEnum.A
+    without.NestedObj
+    without.<!INAPPLICABLE_CANDIDATE!>NestedObj<!>()
+    without.NestedObj.foo()
+
+    obj.Nested()
+    obj.NestedWithClassObject
+    obj.NestedWithClassObject()
+    obj.NestedWithClassObject.foo()
+    obj.NestedEnum.A
+    obj.NestedObj
+    obj.<!INAPPLICABLE_CANDIDATE!>NestedObj<!>()
+    obj.NestedObj.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/nestedClassExtendsOuter.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedClassExtendsOuter.fir.kt
new file mode 100644
index 00000000000..991b4ffb543
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedClassExtendsOuter.fir.kt
@@ -0,0 +1,8 @@
+open class Outer {
+    class Nested : Outer() {
+        fun bar() = foo()
+        fun baz() = super.foo()
+    }
+    
+    fun foo() = 42
+}
diff --git a/compiler/testData/diagnostics/tests/inner/nestedClassExtendsOuterGeneric.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedClassExtendsOuterGeneric.fir.kt
new file mode 100644
index 00000000000..11e0d3b9340
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedClassExtendsOuterGeneric.fir.kt
@@ -0,0 +1,12 @@
+open class Outer<T> {
+    class Nested<U> : Outer<U>() {
+        fun bar(): U = foo()
+        fun baz(): U = super.foo()
+    }
+    class Nested2 : Outer<String>() {
+        fun bar(): String = foo()
+        fun baz(): String = super.foo()
+    }
+    
+    fun foo(): T = null!!
+}
diff --git a/compiler/testData/diagnostics/tests/inner/nestedClassInObject.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedClassInObject.fir.kt
new file mode 100644
index 00000000000..1eba5b37b5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedClassInObject.fir.kt
@@ -0,0 +1,16 @@
+object Object {
+    class NestedClass {
+        fun test() {
+            outerFun()
+            outerVal
+            OuterObject
+            OuterClass()
+        }
+    }
+
+    fun outerFun() {}
+    val outerVal = 4
+
+    object OuterObject
+    class OuterClass
+}
diff --git a/compiler/testData/diagnostics/tests/inner/nestedClassNotAllowed_after.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedClassNotAllowed_after.fir.kt
new file mode 100644
index 00000000000..18778d77efb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedClassNotAllowed_after.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: +NestedClassesInEnumEntryShouldBeInner
+
+class A {
+    inner class B {
+        class C
+    }
+    
+    fun foo() {
+        class B {
+            class C
+        }
+    }
+}
+
+fun foo() {
+    class B {
+        class C
+    }
+}
+
+
+enum class E {
+    E1 {
+        class D
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/nestedClassNotAllowed_before.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedClassNotAllowed_before.fir.kt
new file mode 100644
index 00000000000..7e718dae2bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedClassNotAllowed_before.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: -NestedClassesInEnumEntryShouldBeInner
+
+class A {
+    inner class B {
+        class C
+    }
+    
+    fun foo() {
+        class B {
+            class C
+        }
+    }
+}
+
+fun foo() {
+    class B {
+        class C
+    }
+}
+
+
+enum class E {
+    E1 {
+        class D
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/nestedObject.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedObject.fir.kt
new file mode 100644
index 00000000000..35729b8cae8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedObject.fir.kt
@@ -0,0 +1,12 @@
+// SKIP_TXT
+class Outer {
+    inner class Inner1 {
+        object Obj1
+
+        companion object Obj2
+
+        inner class Inner2 {
+            object Obj3
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/nestedVsInnerAccessOuterMember.fir.kt b/compiler/testData/diagnostics/tests/inner/nestedVsInnerAccessOuterMember.fir.kt
new file mode 100644
index 00000000000..e3806c9636d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/nestedVsInnerAccessOuterMember.fir.kt
@@ -0,0 +1,27 @@
+// NI_EXPECTED_FILE
+
+class Outer {
+    fun function() = 42
+    val property = ""
+    
+    class Nested {
+        fun f() = <!UNRESOLVED_REFERENCE!>function<!>()
+        fun g() = <!UNRESOLVED_REFERENCE!>property<!>
+        fun h() = this@Outer.function()
+        fun i() = this@Outer.property
+    }
+    
+    inner class Inner {
+        fun innerFun() = function()
+        val innerProp = property
+        fun innerThisFun() = this@Outer.function()
+        val innerThisProp = this@Outer.property
+        
+        inner class InnerInner {
+            fun f() = innerFun()
+            fun g() = innerProp
+            fun h() = this@Inner.innerFun()
+            fun i() = this@Inner.innerProp
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/outerGenericParam.fir.kt b/compiler/testData/diagnostics/tests/inner/outerGenericParam.fir.kt
new file mode 100644
index 00000000000..78778d830f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/outerGenericParam.fir.kt
@@ -0,0 +1,13 @@
+class Outer<T> {
+    class Nested {
+        fun foo(t: T) = t
+    }
+    
+    class Nested2<T> {
+        fun foo(t: T) = t
+    }
+    
+    inner class Inner {
+        fun foo(t: T) = t
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/outerProtectedMember.fir.kt b/compiler/testData/diagnostics/tests/inner/outerProtectedMember.fir.kt
new file mode 100644
index 00000000000..5f0064e9227
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/outerProtectedMember.fir.kt
@@ -0,0 +1,13 @@
+// KT-2100
+
+interface I {
+    val x : String
+}
+
+class Foo {
+    protected val x : String = ""
+
+    inner class Inner : I {
+        override val x : String = this@Foo.x
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/inner/outerSuperClassMember.fir.kt b/compiler/testData/diagnostics/tests/inner/outerSuperClassMember.fir.kt
new file mode 100644
index 00000000000..dae32f58c4f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/outerSuperClassMember.fir.kt
@@ -0,0 +1,9 @@
+open class Base {
+    fun foo() {}
+}
+
+class Derived : Base() {
+    class Nested {
+        fun bar() = <!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/classObjectOfNestedClass.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/classObjectOfNestedClass.fir.kt
new file mode 100644
index 00000000000..fb452a3238a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/classObjectOfNestedClass.fir.kt
@@ -0,0 +1,14 @@
+class Outer {
+    class Nested {
+        companion object {
+            fun foo() = 42
+        }
+    }
+    
+    companion object {
+        fun bar() = 239
+    }
+}
+
+fun foo() = Outer.Nested.foo()
+fun bar() = Outer.bar()
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/constructNestedClass.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/constructNestedClass.fir.kt
new file mode 100644
index 00000000000..c0dc2c60a00
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/constructNestedClass.fir.kt
@@ -0,0 +1,17 @@
+class Outer {
+    class Nested {
+        class NestedNested
+    }
+
+    inner class Inner {
+        inner class InnerInner
+    }
+}
+
+fun f1() = Outer()
+fun f2() = Outer.Nested()
+fun f3() = Outer.Nested.NestedNested()
+fun f4() = Outer.<!UNRESOLVED_REFERENCE!>Inner<!>()
+fun f5() = Outer.Inner.<!UNRESOLVED_REFERENCE!>InnerInner<!>()
+fun f6() = Outer().Inner()
+fun f7() = Outer().Inner().InnerInner()
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/dataLocalVariable.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/dataLocalVariable.fir.kt
new file mode 100644
index 00000000000..07b6d50f09c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/dataLocalVariable.fir.kt
@@ -0,0 +1,5 @@
+fun bar(b: Boolean) = b
+
+fun foo(data: List<String>) {
+    bar(data.contains(""))
+}
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/enumConstant.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/enumConstant.fir.kt
new file mode 100644
index 00000000000..431424518a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/enumConstant.fir.kt
@@ -0,0 +1,7 @@
+enum class E {
+    E1,
+    E2 { };
+}
+
+fun foo() = E.E1
+fun bar() = E.E2
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/genericNestedClass.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/genericNestedClass.fir.kt
new file mode 100644
index 00000000000..6ae7ed32c08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/genericNestedClass.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+class Outer {
+    class Nested<T>
+}
+
+fun nested() = Outer.Nested<Int>()
+fun noArguments() = Outer.Nested()
+fun noArgumentsExpectedType(): Outer.Nested<String> = Outer.Nested()
+fun manyArguments() = Outer.Nested<String, Int>()
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/importNestedClass.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/importNestedClass.fir.kt
new file mode 100644
index 00000000000..128bdafcc08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/importNestedClass.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a.kt
+class A {
+    class B {
+        class C
+    }
+}
+
+// FILE: b.kt
+import A.B
+import A.B.C
+
+val a = A()
+val b = B()
+val ab = A.B()
+val c = C()
+val bc = B.C()
+val abc = A.B.C()
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedClassInPackage.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedClassInPackage.fir.kt
new file mode 100644
index 00000000000..07623cb8350
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedClassInPackage.fir.kt
@@ -0,0 +1,8 @@
+package A
+
+class B {
+    class C {
+    }
+}
+
+val a = A.B.C()
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedEnumConstant.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedEnumConstant.fir.kt
new file mode 100644
index 00000000000..a4f370e65ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedEnumConstant.fir.kt
@@ -0,0 +1,9 @@
+class A {
+    enum class E {
+        E1,
+        E2 { };
+    }
+}
+
+fun foo() = A.E.E1
+fun bar() = A.E.E2
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedObjects.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedObjects.fir.kt
new file mode 100644
index 00000000000..c764ad234e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/nestedObjects.fir.kt
@@ -0,0 +1,7 @@
+object A {
+    object B {
+        object C
+    }
+}
+
+val a = A.B.C
diff --git a/compiler/testData/diagnostics/tests/inner/qualifiedExpression/typePosition.fir.kt b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/typePosition.fir.kt
new file mode 100644
index 00000000000..067bc4df710
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/qualifiedExpression/typePosition.fir.kt
@@ -0,0 +1,11 @@
+abstract class Outer {
+    class Nested {
+        class NestedNested
+    }
+    
+    abstract val prop1: Nested
+    abstract val prop2: Nested.NestedNested
+}
+
+fun foo(): Outer.Nested = null!!
+val bar: Outer.Nested.NestedNested = null!!
diff --git a/compiler/testData/diagnostics/tests/inner/referenceToSelfInLocal.fir.kt b/compiler/testData/diagnostics/tests/inner/referenceToSelfInLocal.fir.kt
new file mode 100644
index 00000000000..cc02038def3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/referenceToSelfInLocal.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// KT-4351 Cannot resolve reference to self in init of class local to function
+
+fun f() {
+    class MyClass() {
+        init {
+            val x: MyClass = MyClass()
+        }
+
+        fun member() {
+            val x: MyClass = MyClass()
+        }
+    }
+
+    object MyObject {
+        init {
+            val obj: MyObject = MyObject
+        }
+    }
+
+    val x: MyClass = MyClass()
+}
+
+val closure = {
+    class MyClass {
+        init {
+            val x: MyClass = MyClass()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/resolvePackageClassInObjects.fir.kt b/compiler/testData/diagnostics/tests/inner/resolvePackageClassInObjects.fir.kt
new file mode 100644
index 00000000000..6bc832b5785
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/resolvePackageClassInObjects.fir.kt
@@ -0,0 +1,9 @@
+open class PackageTest
+
+class MoreTest() {
+    companion object: PackageTest() {
+
+    }
+
+    object Some: PackageTest()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inner/selfAnnotationForClassObject.fir.kt b/compiler/testData/diagnostics/tests/inner/selfAnnotationForClassObject.fir.kt
new file mode 100644
index 00000000000..825e6eee634
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/selfAnnotationForClassObject.fir.kt
@@ -0,0 +1,9 @@
+class Test {
+    @ClassObjectAnnotation
+    @NestedAnnotation
+    companion object {
+        annotation class ClassObjectAnnotation
+    }
+
+    annotation class NestedAnnotation
+}
diff --git a/compiler/testData/diagnostics/tests/inner/traits.fir.kt b/compiler/testData/diagnostics/tests/inner/traits.fir.kt
new file mode 100644
index 00000000000..7135bf91889
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/traits.fir.kt
@@ -0,0 +1,11 @@
+// KT-1188
+
+interface Foo {
+    val b : Bar
+    val b1 : Foo.Bar
+    interface Bar {}
+}
+
+interface Foo2 : Foo {
+    val bb1 : Foo.Bar
+}
diff --git a/compiler/testData/diagnostics/tests/inner/visibility.fir.kt b/compiler/testData/diagnostics/tests/inner/visibility.fir.kt
new file mode 100644
index 00000000000..9f77c959bb3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inner/visibility.fir.kt
@@ -0,0 +1,34 @@
+open class Outer {
+    private class PrivateNested
+    private inner class PrivateInner
+
+    protected class ProtectedNested
+    protected inner class ProtectedInner
+
+    public class PublicNested
+    public inner class PublicInner
+}
+
+class Derived : Outer() {
+    fun foo() {
+        Outer.<!INAPPLICABLE_CANDIDATE!>PrivateNested<!>()
+        super.<!INAPPLICABLE_CANDIDATE!>PrivateInner<!>()
+
+        Outer.ProtectedNested()
+        super.ProtectedInner()
+
+        Outer.PublicNested()
+        super.PublicInner()
+    }
+}
+
+fun foo() {
+    Outer.<!INAPPLICABLE_CANDIDATE!>PrivateNested<!>()
+    Outer().<!INAPPLICABLE_CANDIDATE!>PrivateInner<!>()
+
+    Outer.<!INAPPLICABLE_CANDIDATE!>ProtectedNested<!>()
+    Outer().<!INAPPLICABLE_CANDIDATE!>ProtectedInner<!>()
+
+    Outer.PublicNested()
+    Outer().PublicInner()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.fir.kt b/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.fir.kt
new file mode 100644
index 00000000000..08fb60a0a99
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.fir.kt
@@ -0,0 +1,49 @@
+// JAVAC_EXPECTED_FILE
+// FILE: p/G.java
+
+package p;
+
+public interface G<TG> {
+}
+
+// FILE: p/A.kt
+
+package p;
+
+public interface A<TA> {
+    fun foo(p: A<TA>)
+}
+
+// FILE: p/B.java
+
+package p;
+
+public class B<TB> implements A<TB> {
+    void foo(A<TB> p) {}
+}
+
+// FILE: p/C.java
+
+package p;
+
+public class C<TC> extends B<TC> implements A<TC> {
+}
+
+// FILE: p/P.java
+
+package p;
+
+public class P {
+}
+
+// FILE: k.kt
+
+import p.*
+
+abstract class K: C<P>() {
+
+}
+
+abstract class AL: java.util.ArrayList<P>() {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/InheritedGenericFunction.fir.kt b/compiler/testData/diagnostics/tests/j+k/InheritedGenericFunction.fir.kt
new file mode 100644
index 00000000000..de2cd55d562
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/InheritedGenericFunction.fir.kt
@@ -0,0 +1,30 @@
+// FILE: p/A.java
+
+package p;
+
+public interface A {
+    <TA> void foo(TA p);
+}
+
+// FILE: p/B.java
+
+package p;
+
+public class B implements A {
+    <TB> void foo(TB p) {}
+}
+
+// FILE: p/C.java
+
+package p;
+
+public class C extends B implements A {
+}
+
+// FILE: k.kt
+
+import p.*
+
+abstract class K: C() {
+
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/InnerClassFromJava.fir.kt b/compiler/testData/diagnostics/tests/j+k/InnerClassFromJava.fir.kt
new file mode 100644
index 00000000000..cb9f85d3466
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/InnerClassFromJava.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Bar.java
+public class Bar implements Foo {
+public interface I extends Boo {
+}
+}
+
+// FILE: Baz.kt
+public interface Foo {
+    companion object {
+        public val EMPTY: Foo = object : Foo{}
+    }
+}
+
+interface Boo
+
+public class Baz : Bar.I
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/KJKInheritance.fir.kt b/compiler/testData/diagnostics/tests/j+k/KJKInheritance.fir.kt
new file mode 100644
index 00000000000..dc8ab1f5d86
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/KJKInheritance.fir.kt
@@ -0,0 +1,18 @@
+// FILE: K1.kt
+open class KFirst() {
+    fun foo() {
+    }
+}
+
+// FILE: J1.java
+public class J1 extends KFirst {
+    void baz() {}
+}
+
+// FILE: K2.kt
+class K2: J1() {
+    fun bar() {
+        foo()
+        baz()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/KJKInheritanceGeneric.fir.kt b/compiler/testData/diagnostics/tests/j+k/KJKInheritanceGeneric.fir.kt
new file mode 100644
index 00000000000..2c184f5e70d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/KJKInheritanceGeneric.fir.kt
@@ -0,0 +1,17 @@
+// FILE: K1.kt
+open class KFirst<T: java.io.Serializable>() {
+    fun foo(t: T): T = t
+}
+
+// FILE: J1.java
+public class J1 extends KFirst<Integer> {
+    void baz() {}
+}
+
+// FILE: K2.kt
+class K2: J1() {
+    fun bar() {
+        foo(1)
+        baz()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/OverrideVararg.fir.kt b/compiler/testData/diagnostics/tests/j+k/OverrideVararg.fir.kt
new file mode 100644
index 00000000000..2d26101c4ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/OverrideVararg.fir.kt
@@ -0,0 +1,12 @@
+// FILE: Aaa.java
+// http://youtrack.jetbrains.com/issue/KT-1694
+
+public abstract class Aaa {
+    public abstract void foo(String... args);
+}
+
+// FILE: bbb.kt
+
+class Bbb() : Aaa() {
+    override fun foo(vararg args: String?) = Unit
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/Simple.fir.kt b/compiler/testData/diagnostics/tests/j+k/Simple.fir.kt
new file mode 100644
index 00000000000..c82f272c811
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/Simple.fir.kt
@@ -0,0 +1,11 @@
+// FILE: aa/A.java
+package aa;
+
+public class A {
+    public void f() { }
+}
+
+// FILE: B.kt
+import aa.A
+
+fun foo(a: A) = a.f()
diff --git a/compiler/testData/diagnostics/tests/j+k/StaticMembersFromSuperclasses.fir.kt b/compiler/testData/diagnostics/tests/j+k/StaticMembersFromSuperclasses.fir.kt
new file mode 100644
index 00000000000..de425b2100f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/StaticMembersFromSuperclasses.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Aaa.java
+// http://youtrack.jetbrains.com/issue/KT-1880
+
+public class Aaa {
+    public static final int i = 1;
+}
+
+// FILE: Bbb.java
+
+public class Bbb extends Aaa {
+    public static final String i = "s";
+}
+
+// FILE: b.kt
+
+fun foo() = Bbb.<!AMBIGUITY!>i<!>
diff --git a/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.fir.kt b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.fir.kt
new file mode 100644
index 00000000000..842a06b0502
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+// FILE: A.java
+public class A {}
+
+// FILE: X.java
+import org.jetbrains.annotations.NotNull;
+
+public class X<T> {
+    @NotNull T fooN() {return null;}
+    void barN(@NotNull T a) {}
+}
+
+// FILE: Y.java
+public class Y extends X<String> {
+
+}
+
+// FILE: test.kt
+
+fun main() {
+    checkSubtype<Any>(Y().fooN())
+    Y().barN(null);
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.fir.kt b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.fir.kt
new file mode 100644
index 00000000000..610836c63f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+// FILE: A.java
+public class A {}
+
+// FILE: X.java
+import org.jetbrains.annotations.NotNull;
+
+public class X<T> {
+    @NotNull T fooN() {return null;}
+    void barN(@NotNull T a) {}
+}
+
+// FILE: Y.java
+public class Y extends X<A> {
+
+}
+
+// FILE: test.kt
+
+fun main() {
+    checkSubtype<Any>(Y().fooN())
+    Y().barN(null);
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-SpecialTypes.fir.kt b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-SpecialTypes.fir.kt
new file mode 100644
index 00000000000..1823253b9b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-SpecialTypes.fir.kt
@@ -0,0 +1,20 @@
+// FILE: A.java
+public class A {}
+
+// FILE: X.java
+public class X<T> {
+    T foo() {return null;}
+    void bar(T a) {}
+}
+
+// FILE: Y.java
+public class Y extends X<String> {
+
+}
+
+// FILE: test.kt
+
+fun main() {
+    Y().foo().length
+    Y().bar(null)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-UserTypes.fir.kt b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-UserTypes.fir.kt
new file mode 100644
index 00000000000..cc28efdcaa2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-UserTypes.fir.kt
@@ -0,0 +1,20 @@
+// FILE: A.java
+public class A {}
+
+// FILE: X.java
+public class X<T> {
+    T foo() {return null;}
+    void bar(T a) {}
+}
+
+// FILE: Y.java
+public class Y extends X<A> {
+
+}
+
+// FILE: test.kt
+
+fun main() {
+    Y().foo().hashCode()
+    Y().bar(null)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/UnboxingNulls.fir.kt b/compiler/testData/diagnostics/tests/j+k/UnboxingNulls.fir.kt
new file mode 100644
index 00000000000..4e69df6f24c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/UnboxingNulls.fir.kt
@@ -0,0 +1,13 @@
+// FILE: a/Test.java
+package a;
+
+public class Test<T> {
+  T t() {return null;}
+}
+// FILE: b.kt
+package a
+
+fun foo() {
+  // If this fails, it means that we have broken the rule that Java returns are always nullable
+  a.<!UNRESOLVED_REFERENCE!>Test<!><Int>().<!UNRESOLVED_REFERENCE!>t<!>() + 1
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/accessClassObjectFromJava.fir.kt b/compiler/testData/diagnostics/tests/j+k/accessClassObjectFromJava.fir.kt
new file mode 100644
index 00000000000..af234b504c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/accessClassObjectFromJava.fir.kt
@@ -0,0 +1,10 @@
+class Foo {
+  companion object {
+    val bar = 1
+
+    fun test(a: Foo.`object`) {
+
+    }
+
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/ambiguousSamAdapters.fir.kt b/compiler/testData/diagnostics/tests/j+k/ambiguousSamAdapters.fir.kt
new file mode 100644
index 00000000000..4b0edc1fab3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/ambiguousSamAdapters.fir.kt
@@ -0,0 +1,17 @@
+// FILE: A.java
+import java.io.Closeable;
+
+public class A {
+    public static void foo(Runnable r) {
+    }
+
+    public static void foo(Closeable c) {
+    }
+}
+
+// FILE: test.kt
+
+fun main() {
+    A.<!AMBIGUITY!>foo<!> { "Hello!" }
+    A.foo(Runnable { "Hello!" })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/annotationWithArgumentsMissingDependencies.fir.kt b/compiler/testData/diagnostics/tests/j+k/annotationWithArgumentsMissingDependencies.fir.kt
new file mode 100644
index 00000000000..90f3fc6ea16
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/annotationWithArgumentsMissingDependencies.fir.kt
@@ -0,0 +1,12 @@
+// FILE: A.java
+@missing.Ann(x = "")
+public class A {
+    @missing.Ann(1)
+    public String foo() {}
+}
+
+// FILE: main.kt
+
+fun main() {
+    A().foo().length
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/annotationsInheritance.fir.kt b/compiler/testData/diagnostics/tests/j+k/annotationsInheritance.fir.kt
new file mode 100644
index 00000000000..1764b09b343
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/annotationsInheritance.fir.kt
@@ -0,0 +1,19 @@
+// FILE: MyAnnotation.java
+public @interface MyAnnotation {
+}
+// FILE: MyAnnoClass.java
+public class MyAnnoClass implements MyAnnotation {
+//...
+}
+
+// FILE: main.kt
+
+val ann: MyAnnotation = MyAnnoClass()
+
+fun foo(x: MyAnnoClass) {
+    bar(x)
+}
+
+fun bar(y: MyAnnotation) {
+    y.hashCode()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/arrayOfStarParametrized.fir.kt b/compiler/testData/diagnostics/tests/j+k/arrayOfStarParametrized.fir.kt
new file mode 100644
index 00000000000..d18fda6e7fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/arrayOfStarParametrized.fir.kt
@@ -0,0 +1,14 @@
+// !CHECK_TYPE
+
+// FILE: A.java
+public class A<T> {
+    public A<T>[] baz() { return null; }
+}
+
+
+// FILE: main.kt
+
+fun foo1(x: A<*>) = x.baz()
+fun foo2(x: A<*>) {
+    x.baz() checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out A<*>>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/brokenCode/classDuplicates.fir.kt b/compiler/testData/diagnostics/tests/j+k/brokenCode/classDuplicates.fir.kt
new file mode 100644
index 00000000000..928b78be8ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/brokenCode/classDuplicates.fir.kt
@@ -0,0 +1,13 @@
+// FILE: Hello.kt
+private class Hello()
+{
+    val a = 4
+}
+
+fun test() {
+    // no exception is thrown (see KT-3897)
+    Hello().a
+}
+
+// FILE: Hello.java
+public class Hello {}
diff --git a/compiler/testData/diagnostics/tests/j+k/brokenCode/fieldDuplicates.fir.kt b/compiler/testData/diagnostics/tests/j+k/brokenCode/fieldDuplicates.fir.kt
new file mode 100644
index 00000000000..857d09668c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/brokenCode/fieldDuplicates.fir.kt
@@ -0,0 +1,13 @@
+// FILE: A.java
+
+public class A {
+    public String foo;
+    public String foo = "";
+}
+
+// FILE: main.kt
+
+fun foo() {
+    // no exception is thrown (see KT-3898)
+    A().<!AMBIGUITY!>foo<!>
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/callableReferencesStaticMemberClash.fir.kt b/compiler/testData/diagnostics/tests/j+k/callableReferencesStaticMemberClash.fir.kt
new file mode 100644
index 00000000000..86149c53609
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/callableReferencesStaticMemberClash.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: A.java
+public class A {
+    public static void foo() {}
+    public static void foo(String x) {}
+
+    private void foo(int y) {}
+}
+
+// FILE: main.kt
+
+fun baz(x: (String) -> Unit) {}
+
+fun bar() {
+    baz(A::foo)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/canDeclareIfSamAdapterIsInherited.fir.kt b/compiler/testData/diagnostics/tests/j+k/canDeclareIfSamAdapterIsInherited.fir.kt
new file mode 100644
index 00000000000..f999e6b8e83
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/canDeclareIfSamAdapterIsInherited.fir.kt
@@ -0,0 +1,11 @@
+// FILE: Super.java
+public class Super {
+    void foo(Runnable r) {
+    }
+}
+
+// FILE: Sub.kt
+class Sub() : Super() {
+    fun foo(r : (() -> Unit)?) {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/charBuffer.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/charBuffer.fir.kt
new file mode 100644
index 00000000000..1b32d392513
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/charBuffer.fir.kt
@@ -0,0 +1,22 @@
+// FILE: CharBuffer.java
+
+public class CharBuffer implements CharSequence {
+    public final int length() {
+        return 0;
+    }
+
+    public final char charAt(int index) {
+        return get(position() + checkIndex(index, 1));
+    }
+
+    // The key problem here is that `get` has the same signature as kotlin.CharSequence.get but completely different semantics
+    public abstract char get(int index);
+    public abstract CharBuffer subSequence(int start, int end);
+}
+
+// FILE: main.kt
+
+fun test(cb: CharBuffer) {
+    cb.get(0)
+    (cb as CharSequence).get(0)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/collectionStringImpl.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/collectionStringImpl.fir.kt
new file mode 100644
index 00000000000..08b86b53d45
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/collectionStringImpl.fir.kt
@@ -0,0 +1,85 @@
+// FILE: CollectionStringImpl.java
+
+import java.util.Collection;
+import java.util.Iterator;
+
+public class CollectionStringImpl implements Collection<String> {
+    @Override
+    public int size() {
+        return 0;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return false;
+    }
+
+    @Override
+    public boolean contains(Object o) {
+        return false;
+    }
+
+
+    @Override
+    public Iterator<String> iterator() {
+        return null;
+    }
+
+
+    @Override
+    public Object[] toArray() {
+        return new Object[0];
+    }
+
+
+    @Override
+    public <T> T[] toArray(T[] a) {
+        return null;
+    }
+
+    @Override
+    public boolean add(String s) {
+        return false;
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        return false;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> c) {
+        return false;
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends String> c) {
+        return false;
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> c) {
+        return false;
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> c) {
+        return false;
+    }
+
+    @Override
+    public void clear() {
+
+    }
+
+    public boolean contains(String o) {
+        return true;
+    }
+}
+
+// FILE: main.kt
+
+fun test(x: CollectionStringImpl) {
+    x.contains("")
+    (x as Collection<String>).contains("")
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/commonCollections.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/commonCollections.fir.kt
new file mode 100644
index 00000000000..2d563de8a26
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/commonCollections.fir.kt
@@ -0,0 +1,28 @@
+import java.util.*
+fun foo() {
+    val al = ArrayList<String>()
+    al.size
+    al.contains(1)
+    al.contains("")
+
+    al.remove("")
+    al.removeAt(1)
+
+    val hs = HashSet<String>()
+    hs.size
+    hs.contains(1)
+    hs.contains("")
+
+    hs.remove("")
+
+
+    val hm = HashMap<String, Int>()
+    hm.size
+    hm.containsKey(1)
+    hm.containsKey("")
+
+    hm[1]
+    hm[""]
+
+    hm.remove("")
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/contains.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/contains.fir.kt
new file mode 100644
index 00000000000..8caaa33cfd5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/contains.fir.kt
@@ -0,0 +1,66 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -PARAMETER_NAME_CHANGED_ON_OVERRIDE
+// JAVAC_EXPECTED_FILE
+// FILE: A.java
+
+abstract public class A<T> implements java.util.Collection<T> {
+    public boolean contains(Object x) {return false;}
+}
+
+// FILE: B.java
+
+abstract public class B implements java.util.Collection<String> {
+    public boolean contains(Object x) {return false;}
+}
+
+// FILE: IC.java
+public interface IC extends java.util.Collection<String> {
+    public boolean contains(Object x);
+}
+
+// FILE: main.kt
+abstract class KA<T> : java.util.AbstractList<T>() {
+    override fun contains(x: T) = false
+}
+
+abstract class KB : java.util.AbstractList<String>(), IC {
+    override fun contains(element: String) = false
+}
+
+
+// Raw?
+
+fun foo(
+        a: A<String>, b: B, ic: IC,
+        ka: KA<String>, kb: KB,
+        al: java.util.ArrayList<String>
+) {
+    a.contains("")
+    a.contains(1)
+    "" in a
+    1 in a
+
+    b.contains("")
+    b.contains(1)
+    "" in b
+    1 in b
+
+    ic.contains("")
+    ic.contains(1)
+    "" in ic
+    1 in ic
+
+    ka.contains("")
+    ka.contains(1)
+    "" in ka
+    1 in ka
+
+    kb.contains("")
+    kb.contains(1)
+    "" in kb
+    1 in kb
+
+    al.contains("")
+    al.contains(1)
+    "" in al
+    1 in al
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/containsAll.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/containsAll.fir.kt
new file mode 100644
index 00000000000..94b462adcc4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/containsAll.fir.kt
@@ -0,0 +1,56 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -PARAMETER_NAME_CHANGED_ON_OVERRIDE
+// JAVAC_EXPECTED_FILE
+// FILE: A.java
+import java.util.*;
+
+abstract public class A<T> implements java.util.Collection<T> {
+    public boolean containsAll(Collection<?> x) {return false;}
+}
+
+// FILE: B.java
+import java.util.*;
+
+abstract public class B implements java.util.Collection<String> {
+    public boolean containsAll(Collection<?> x) {return false;}
+}
+
+// FILE: IC.java
+import java.util.*;
+
+public interface IC extends java.util.Collection<String> {
+    public boolean containsAll(Collection<?> x);
+}
+
+// FILE: main.kt
+abstract class KA<T> : java.util.AbstractList<T>() {
+    override fun containsAll(x: Collection<T>) = false
+}
+
+abstract class KB : java.util.AbstractList<String>(), IC {
+    override fun containsAll(elements: Collection<String>) = false
+}
+
+fun foo(
+        a: A<String>, b: B, ic: IC,
+        ka: KA<String>, kb: KB,
+        al: java.util.ArrayList<String>,
+        cs: Collection<String>, ca: Collection<Any?>
+) {
+    a.containsAll(cs)
+    a.containsAll(ca)
+
+    b.containsAll(cs)
+    b.containsAll(ca)
+
+    ic.containsAll(cs)
+    ic.containsAll(ca)
+
+    ka.containsAll(cs)
+    ka.containsAll(ca)
+
+    kb.containsAll(cs)
+    kb.containsAll(ca)
+
+    al.containsAll(cs)
+    al.containsAll(ca)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/containsAndOverload.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/containsAndOverload.fir.kt
new file mode 100644
index 00000000000..14ba0abc693
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/containsAndOverload.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -PARAMETER_NAME_CHANGED_ON_OVERRIDE
+
+// FILE: A.java
+abstract public class A implements java.util.Collection<String> {
+    public boolean contains(Object x) {return false;}
+    public boolean contains(String x) {return false;}
+}
+
+// FILE: main.kt
+abstract class KA : A() {
+    override fun contains(x: String) = false
+}
+
+fun foo(a: A, ka: KA) {
+    a.contains("")
+    a.contains(1)
+    "" in a
+    1 in a
+
+    ka.contains("")
+    ka.contains(1)
+    "" in ka
+    1 in ka
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/getCharSequence.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/getCharSequence.fir.kt
new file mode 100644
index 00000000000..40c49d09a1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/getCharSequence.fir.kt
@@ -0,0 +1,30 @@
+// FILE: A.java
+abstract public class A implements CharSequence {
+    public char charAt(int x) { }
+    public int length() { return 1; }
+}
+
+// FILE: C.java
+abstract public class C implements CharSequence {
+    public char get(int x) { }
+    public int length() { return 1; }
+}
+
+// FILE: main.kt
+
+abstract class B : A(), CharSequence {
+    override operator fun get(index: Int) = '1'
+    override val length: Int get() = 1
+}
+
+fun main(a: A, b: B, c: C) {
+    a[0]
+    b[0]
+    c[0]
+
+    a.get(0)
+    b.get(0)
+    c.get(0)
+
+    a.length + b.length + c.length
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantCharAtAbstract.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantCharAtAbstract.fir.kt
new file mode 100644
index 00000000000..8462a985da9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantCharAtAbstract.fir.kt
@@ -0,0 +1,19 @@
+// FILE: A.java
+
+public abstract class A {
+    abstract public char charAt(int i);
+}
+
+// FILE: B.java
+
+abstract public class B extends A implements CharSequence {
+    public char charAt(int i) { return '1'; }
+}
+
+// FILE: main.kt
+
+abstract class C1 : B()
+
+abstract class C2 : B() {
+    override fun get(index: Int) = '1'
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplCharSequence.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplCharSequence.fir.kt
new file mode 100644
index 00000000000..e544b2be1c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplCharSequence.fir.kt
@@ -0,0 +1,25 @@
+// FILE: AImpl.java
+
+abstract public class AImpl {
+    public char charAt(int index) {
+        return '1';
+    }
+
+    public final int length() { return 1; }
+}
+
+// FILE: A.java
+public class A extends AImpl implements CharSequence {
+    public CharSequence subSequence(int start, int end) {
+        return null;
+    }
+}
+
+// FILE: X.kt
+class X : A()
+
+fun main() {
+    val x = X()
+    x[0]
+    x.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplCharSequenceKotlin.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplCharSequenceKotlin.fir.kt
new file mode 100644
index 00000000000..65a03831ee2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplCharSequenceKotlin.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: AImpl.kt
+
+abstract class AImpl {
+    fun charAt(index: Int): Char {
+        return '1'
+    }
+
+    fun length(): Int {
+        return 1
+    }
+}
+
+// FILE: A.java
+public class A extends AImpl implements CharSequence {
+    public CharSequence subSequence(int start, int end) {
+        return null;
+    }
+}
+
+// FILE: X.kt
+class X : A()
+
+fun main() {
+    val x = X()
+    x[0]
+    x.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplMutableList.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplMutableList.fir.kt
new file mode 100644
index 00000000000..68b8dad2acd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplMutableList.fir.kt
@@ -0,0 +1,119 @@
+// FILE: AImpl.java
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+public abstract class AImpl {
+    public int size() {
+        return 0;
+    }
+
+    public boolean isEmpty() {
+        return false;
+    }
+
+    public boolean contains(Object o) {
+        return false;
+    }
+
+    public Iterator<String> iterator() {
+        return null;
+    }
+
+    public Object[] toArray() {
+        return new Object[0];
+    }
+
+    public <T> T[] toArray(T[] a) {
+        return null;
+    }
+
+    public boolean add(String s) {
+        return false;
+    }
+
+    public boolean remove(Object o) {
+        return false;
+    }
+
+    public boolean containsAll(Collection<?> c) {
+        return false;
+    }
+
+    public boolean addAll(Collection<? extends String> c) {
+        return false;
+    }
+
+    public boolean addAll(int index, Collection<? extends String> c) {
+        return false;
+    }
+
+    public boolean removeAll(Collection<?> c) {
+        return false;
+    }
+
+    public boolean retainAll(Collection<?> c) {
+        return false;
+    }
+
+    public void clear() {
+
+    }
+
+    public String get(int index) {
+        return null;
+    }
+
+    public String set(int index, String element) {
+        return null;
+    }
+
+    public void add(int index, String element) {
+
+    }
+
+    public String remove(int index) {
+        return null;
+    }
+
+    public int indexOf(Object o) {
+        return 0;
+    }
+
+    public int lastIndexOf(Object o) {
+        return 0;
+    }
+
+    public ListIterator<String> listIterator() {
+        return null;
+    }
+
+    public ListIterator<String> listIterator(int index) {
+        return null;
+    }
+
+    public List<String> subList(int fromIndex, int toIndex) {
+        return null;
+    }
+}
+
+
+// FILE: A.java
+import java.util.List;
+
+public class A extends AImpl implements List<String> {
+
+}
+
+// FILE: X.kt
+class X : A()
+
+fun main() {
+    val x = X()
+    x[0]
+    x.size
+    x.remove("")
+    x.remove(1)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplMutableListKotlin.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplMutableListKotlin.fir.kt
new file mode 100644
index 00000000000..4c7f99d2c13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantImplMutableListKotlin.fir.kt
@@ -0,0 +1,106 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: AImpl.kt
+
+public abstract class AImpl {
+    fun add(element: String): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun remove(element: String): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun addAll(elements: Collection<String>): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun addAll(index: Int, elements: Collection<String>): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun removeAll(elements: Collection<String>): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun retainAll(elements: Collection<String>): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun clear() {
+        throw UnsupportedOperationException()
+    }
+
+    fun set(index: Int, element: String): String {
+        throw UnsupportedOperationException()
+    }
+
+    fun add(index: Int, element: String) {
+        throw UnsupportedOperationException()
+    }
+
+    fun remove(index: Int): String {
+        throw UnsupportedOperationException()
+    }
+
+    fun listIterator(): MutableListIterator<String> {
+        throw UnsupportedOperationException()
+    }
+
+    fun listIterator(index: Int): MutableListIterator<String> {
+        throw UnsupportedOperationException()
+    }
+
+    fun subList(fromIndex: Int, toIndex: Int): MutableList<String> {
+        throw UnsupportedOperationException()
+    }
+
+    val size: Int
+        get() = throw UnsupportedOperationException()
+
+    fun isEmpty(): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun contains(element: Any?): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun containsAll(elements: Collection<*>): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+    fun get(index: Int): String {
+        throw UnsupportedOperationException()
+    }
+
+    fun indexOf(element: String): Int {
+        throw UnsupportedOperationException()
+    }
+
+    fun lastIndexOf(element: String): Int {
+        throw UnsupportedOperationException()
+    }
+
+    fun iterator(): MutableIterator<String> {
+        throw UnsupportedOperationException()
+    }
+}
+
+
+// FILE: A.java
+import java.util.List;
+
+public class A extends AImpl implements List<String> {
+
+}
+
+// FILE: X.kt
+class X : A()
+
+fun main() {
+    val x = X()
+    x[0]
+    x.size
+    x.remove("")
+    x.remove(1)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantMapGetAbstract.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantMapGetAbstract.fir.kt
new file mode 100644
index 00000000000..409e6ed8c49
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/irrelevantMapGetAbstract.fir.kt
@@ -0,0 +1,19 @@
+// FILE: Dict.java
+
+public abstract class Dict<K, V> {
+    abstract public V get(Object key);
+}
+
+// FILE: MHashtable.java
+
+abstract public class MHashtable<X, Y> extends Dict<X, Y> implements java.util.Map<X, Y> {
+    public V get(Object key) { return null; }
+}
+
+// FILE: main.kt
+
+abstract class C1 : MHashtable<String, Int>()
+
+abstract class C2 : MHashtable<String, Int>() {
+    override fun get(key: String) = 1
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/mapGetOverride.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/mapGetOverride.fir.kt
new file mode 100644
index 00000000000..c357b29c46a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/mapGetOverride.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VALUE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+// JAVAC_EXPECTED_FILE
+// FILE: MyMap.java
+
+abstract public class MyMap extends java.util.AbstractMap<Double, CharSequence> {
+    String get(Object q) { }
+}
+
+// FILE: main.kt
+
+fun foo(m: MyMap) {
+    var x: String? = m.get(1.0)
+    x = m[2.0]
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/overridesBuiltinNoMagic.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/overridesBuiltinNoMagic.fir.kt
new file mode 100644
index 00000000000..a25795d18de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/overridesBuiltinNoMagic.fir.kt
@@ -0,0 +1,163 @@
+// FILE: X.java
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+public class X implements java.util.List<String> {
+    @Override
+    public int size() {
+        return 0;
+    }
+
+    public int getSize() {
+        return 0;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return false;
+    }
+
+    public boolean contains(String o) {
+        return false;
+    }
+
+    @Override
+    public boolean contains(Object o) {
+        return false;
+    }
+
+    @NotNull
+    @Override
+    public Iterator<String> iterator() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Object[] toArray() {
+        return new Object[0];
+    }
+
+    @NotNull
+    @Override
+    public <T> T[] toArray(T[] a) {
+        return null;
+    }
+
+    @Override
+    public boolean add(String s) {
+        return false;
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        return false;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> c) {
+        return false;
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends String> c) {
+        return false;
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends String> c) {
+        return false;
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> c) {
+        return false;
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> c) {
+        return false;
+    }
+
+    @Override
+    public void clear() {
+
+    }
+
+    @Override
+    public String get(int index) {
+        return null;
+    }
+
+    @Override
+    public String set(int index, String element) {
+        return null;
+    }
+
+    @Override
+    public void add(int index, String element) {
+
+    }
+
+    @Override
+    public String remove(int index) {
+        return null;
+    }
+
+    public String removeAt(int index) {
+        return null;
+    }
+
+    @Override
+    public int indexOf(Object o) {
+        return 0;
+    }
+
+    @Override
+    public int lastIndexOf(Object o) {
+        return 0;
+    }
+
+    @NotNull
+    @Override
+    public ListIterator<String> listIterator() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public ListIterator<String> listIterator(int index) {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public List<String> subList(int fromIndex, int toIndex) {
+        return null;
+    }
+}
+
+// FILE: main.kt
+
+class Y : X()
+class Y2 : X() {
+    override fun removeAt(index: Int) = ""
+}
+
+fun main() {
+    X().remove("")
+    X().removeAt(1)
+
+    val y: MutableList<String> = Y()
+    y.removeAt(1)
+
+    Y().remove("")
+    Y().removeAt(1)
+
+    X().remove("")
+    X().removeAt(1)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/removeAt.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/removeAt.fir.kt
new file mode 100644
index 00000000000..bf5a5332a11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/removeAt.fir.kt
@@ -0,0 +1,23 @@
+// JAVAC_EXPECTED_FILE
+// FILE: A.java
+abstract public class A<F> extends B<F> {
+    public F remove(int x) { }
+    public boolean remove(Object x) { }
+}
+
+// FILE: main.kt
+import java.util.*;
+
+abstract class B<T> : MutableList<T>, AbstractList<T>() {
+    override fun removeAt(index: Int): T = null!!
+    override fun remove(element: T): Boolean = null!!
+}
+
+fun main(a: A<String>, b: B<String>, c: ArrayList<String>) {
+    a.remove("")
+    a.removeAt(0)
+    b.remove("")
+    b.removeAt(0)
+    c.remove("")
+    c.removeAt(0)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/removeAtInt.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/removeAtInt.fir.kt
new file mode 100644
index 00000000000..ff15421906f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/removeAtInt.fir.kt
@@ -0,0 +1,23 @@
+// JAVAC_EXPECTED_FILE
+// FILE: A.java
+abstract public class A extends B {
+    public Integer removeAt(int x) { }
+    public boolean remove(Integer x) { }
+}
+
+// FILE: main.kt
+import java.util.*;
+
+abstract class B : MutableList<Int>, AbstractList<Int>() {
+    override fun removeAt(index: Int): Int = null!!
+    override fun remove(element: Int): Boolean = null!!
+}
+
+fun main(a: A, b: B, c: ArrayList<Int>) {
+    a.remove(1)
+    a.removeAt(0)
+    b.remove(1)
+    b.removeAt(0)
+    c.<!AMBIGUITY!>remove<!>(1)
+    c.removeAt(0)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectionOverrides/sizeFromKotlinOverriddenInJava.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/sizeFromKotlinOverriddenInJava.fir.kt
new file mode 100644
index 00000000000..bd214138ce0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectionOverrides/sizeFromKotlinOverriddenInJava.fir.kt
@@ -0,0 +1,13 @@
+// FILE: A.java
+
+abstract public class A<F> extends MyList<F> {
+    int getSize() { return 0; }
+}
+
+// FILE: main.kt
+
+abstract class MyList<G> : Collection<G> {}
+
+fun main(a: A<String>) {
+    a.size
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/collectorInference.fir.kt b/compiler/testData/diagnostics/tests/j+k/collectorInference.fir.kt
new file mode 100644
index 00000000000..6ae7cf7606e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/collectorInference.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// SKIP_TXT
+// FULL_JDK
+
+import java.util.stream.Collectors
+import java.util.stream.Stream
+
+fun test(a: Stream<String>) {
+    a.<!INAPPLICABLE_CANDIDATE!>collect<!>(Collectors.toList()) <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><MutableList<String>>() }
+    // actually the inferred type is platform
+    a.<!INAPPLICABLE_CANDIDATE!>collect<!>(Collectors.toList()) <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><List<String?>>() }
+}
+
diff --git a/compiler/testData/diagnostics/tests/j+k/computeIfAbsentConcurrent.fir.kt b/compiler/testData/diagnostics/tests/j+k/computeIfAbsentConcurrent.fir.kt
new file mode 100644
index 00000000000..abd047b6ccd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/computeIfAbsentConcurrent.fir.kt
@@ -0,0 +1,22 @@
+// FILE: MyFunc.java
+public interface MyFunc<K, V> {
+    V apply(K String);
+}
+
+// FILE: ConcMap.java
+public interface ConcMap<K, V> {
+    V computeIfAbsent(K key, MyFunc<? super K,? extends V> mappingFunction);
+}
+
+// FILE: ConcHashMap.java
+public class ConcHashMap<K, V> implements ConcMap<K, V> {
+    @Override
+    V computeIfAbsent(K key, MyFunc<? super K,? extends V> mappingFunction) { }
+}
+
+// FILE: main.kt
+
+public fun concurrentMap() {
+    val map = ConcHashMap<String, String>()
+    map.computeIfAbsent("") { "" } // here
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/contravariantIterable.fir.kt b/compiler/testData/diagnostics/tests/j+k/contravariantIterable.fir.kt
new file mode 100644
index 00000000000..6a78efd5e2e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/contravariantIterable.fir.kt
@@ -0,0 +1,20 @@
+// FILE: A.java
+import java.util.*;
+public class A {
+    public static void foo(Iterable<? super CharSequence> x) {}
+    public static void bar(Iterator<? super CharSequence> x) {}
+}
+
+// FILE: main.kt
+
+fun test(x: List<String>, y: List<*>, z: MutableList<*>, w: MutableList<in CharSequence>) {
+    A.foo(x)
+    A.foo(y)
+    A.foo(z)
+    A.foo(w)
+
+    A.bar(x.iterator())
+    A.bar(y.iterator())
+    A.bar(z.iterator())
+    A.bar(w.iterator())
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/defaultMethods.fir.kt b/compiler/testData/diagnostics/tests/j+k/defaultMethods.fir.kt
new file mode 100644
index 00000000000..2655a46b921
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/defaultMethods.fir.kt
@@ -0,0 +1,166 @@
+// FILE: JavaInterface.java
+
+public interface JavaInterface {
+    static String testStatic() {
+        return "OK";
+    }
+
+    default String test() {
+        return "OK";
+    }
+
+    default String testOverride() {
+        return "OK";
+    }
+}
+
+// FILE: 1.kt
+import JavaInterface.testStatic
+
+interface KotlinInterface : JavaInterface {
+    fun fooo() {
+        testStatic()
+        super.test()
+
+        object  {
+            fun run () {
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val propertyy: String
+        get() {
+            super.test()
+
+            object  {
+                fun run () {
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+
+    override fun testOverride(): String {
+        return "OK";
+    }
+}
+
+interface KotlinInterfaceIndirectInheritance : KotlinInterface {
+    fun foooo() {
+        testStatic()
+        super.test()
+
+        object  {
+            fun run () {
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val propertyyy: String
+        get() {
+            super.test()
+
+            object  {
+                fun run () {
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+open class KotlinClass : JavaInterface {
+    fun foo() {
+        testStatic()
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance : KotlinClass() {
+    fun foo2(){
+        testStatic()
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property2: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance2 : KotlinInterfaceIndirectInheritance {
+    fun foo() {
+        testStatic()
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+fun test() {
+    JavaInterface.testStatic()
+    KotlinClass().foo()
+    KotlinClass().property
+    KotlinClassIndirectInheritance2().foo()
+    KotlinClassIndirectInheritance2().property
+
+    KotlinClass().test()
+    KotlinClass().property
+    KotlinClass().testOverride()
+    KotlinClassIndirectInheritance().testOverride()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/defaultMethodsIndirectInheritance.fir.kt b/compiler/testData/diagnostics/tests/j+k/defaultMethodsIndirectInheritance.fir.kt
new file mode 100644
index 00000000000..6aafef0fac0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/defaultMethodsIndirectInheritance.fir.kt
@@ -0,0 +1,79 @@
+// FILE: JavaInterfaceBase.java
+
+public interface JavaInterfaceBase {
+    default String test() {
+        return "OK";
+    }
+
+    default String testOverride() {
+        return "OK";
+    }
+}
+
+// FILE: JavaInterface.java
+
+public interface JavaInterface extends JavaInterfaceBase {
+    static String testStatic() {
+        return "OK";
+    }
+}
+
+
+// FILE: 1.kt
+import JavaInterface.testStatic
+
+interface KotlinInterface : JavaInterface {
+    fun fooo() {
+        testStatic()
+        super.test()
+        test()
+        testOverride()
+    }
+
+    override fun testOverride(): String {
+        return "OK";
+    }
+}
+
+interface KotlinInterfaceIndirectInheritance : KotlinInterface {
+    fun foooo() {
+        testStatic()
+        super.test()
+        testOverride()
+        super.testOverride()
+    }
+}
+
+open class KotlinClass : JavaInterface {
+    fun foo(){
+        testStatic()
+        super.test()
+        super.testOverride()
+    }
+}
+
+class KotlinClassIndirectInheritance : KotlinClass() {
+    fun foo2(){
+        testStatic()
+        super.test()
+        super.testOverride()
+    }
+}
+
+class KotlinClassIndirectInheritance2 : KotlinInterfaceIndirectInheritance {
+    fun foo(){
+        testStatic()
+        super.test()
+        super.testOverride()
+    }
+}
+
+fun test() {
+    JavaInterface.testStatic()
+    KotlinClass().foo()
+    KotlinClassIndirectInheritance2().foo()
+
+    KotlinClass().test()
+    KotlinClass().testOverride()
+    KotlinClassIndirectInheritance().testOverride()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/defaultMethods_warning.fir.kt b/compiler/testData/diagnostics/tests/j+k/defaultMethods_warning.fir.kt
new file mode 100644
index 00000000000..e7b765c005a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/defaultMethods_warning.fir.kt
@@ -0,0 +1,168 @@
+//!LANGUAGE: -DefaultMethodsCallFromJava6TargetError
+// FILE: JavaInterface.java
+
+public interface JavaInterface {
+    static String testStatic() {
+        return "OK";
+    }
+
+    default String test() {
+        return "OK";
+    }
+
+    default String testOverride() {
+        return "OK";
+    }
+}
+
+// FILE: 1.kt
+
+import JavaInterface.testStatic
+
+interface KotlinInterface : JavaInterface {
+    fun fooo() {
+        testStatic()
+        super.test()
+
+        object  {
+            fun run () {
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val propertyy: String
+        get() {
+            super.test()
+
+            object  {
+                fun run () {
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+
+    override fun testOverride(): String {
+        return "OK";
+    }
+}
+
+interface KotlinInterfaceIndirectInheritance : KotlinInterface {
+    fun foooo() {
+        testStatic()
+        super.test()
+
+        object  {
+            fun run () {
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val propertyyy: String
+        get() {
+            super.test()
+
+            object  {
+                fun run () {
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+open class KotlinClass : JavaInterface {
+    fun foo(){
+        testStatic()
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance : KotlinClass() {
+    fun foo2(){
+        testStatic()
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property2: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance2 : KotlinInterfaceIndirectInheritance {
+    fun foo(){
+        testStatic()
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+fun test() {
+    JavaInterface.testStatic()
+    KotlinClass().foo()
+    KotlinClass().property
+    KotlinClassIndirectInheritance2().foo()
+    KotlinClassIndirectInheritance2().property
+
+    KotlinClass().test()
+    KotlinClass().property
+    KotlinClass().testOverride()
+    KotlinClassIndirectInheritance().testOverride()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/deprecations/forFakeOverrides.fir.kt b/compiler/testData/diagnostics/tests/j+k/deprecations/forFakeOverrides.fir.kt
new file mode 100644
index 00000000000..6100afe2c4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/deprecations/forFakeOverrides.fir.kt
@@ -0,0 +1,36 @@
+// FILE: J.java
+public interface J {
+    @Deprecated
+    public void foo();
+
+    @Deprecated
+    public String bar();
+
+    @Deprecated
+    public CharSequence baz();
+}
+// FILE: J2.java
+public interface J2 extends J, K {
+}
+
+// FILE: main.kt
+interface K {
+    fun bar(): CharSequence
+    fun baz(): String
+}
+
+interface A : J, K
+
+fun main(j: J, j2: J2, a: A) {
+    j.foo()
+    j2.foo()
+    a.foo()
+
+    j.bar()
+    j2.bar()
+    a.bar()
+
+    j.baz()
+    j2.baz()
+    a.baz()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/deprecations/forMixedOverride.fir.kt b/compiler/testData/diagnostics/tests/j+k/deprecations/forMixedOverride.fir.kt
new file mode 100644
index 00000000000..2caf9e3d1bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/deprecations/forMixedOverride.fir.kt
@@ -0,0 +1,27 @@
+// FILE: J.java
+public class J {
+    @Deprecated
+    public void foo() {}
+}
+// FILE: J2.java
+public class J2 extends J implements WithDeprecation {
+    @Override
+    public void foo() {}
+}
+
+// FILE: main.kt
+interface WithDeprecation {
+    @Deprecated("")
+    fun foo()
+}
+
+class A : J(), WithDeprecation {
+    override fun foo() {}
+}
+
+fun main() {
+    J().foo()
+
+    J2().foo()
+    A().foo()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/deprecations/forOverrides.fir.kt b/compiler/testData/diagnostics/tests/j+k/deprecations/forOverrides.fir.kt
new file mode 100644
index 00000000000..e06bfaf2060
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/deprecations/forOverrides.fir.kt
@@ -0,0 +1,23 @@
+// FILE: J.java
+public interface J {
+    @Deprecated
+    public void foo();
+
+}
+// FILE: J2.java
+public interface J2 extends J {
+    @Override
+    public void foo();
+}
+
+// FILE: main.kt
+
+interface A : J {
+    override fun foo()
+}
+
+fun main(j: J, j2: J2, a: A) {
+    j.foo()
+    j2.foo()
+    a.foo()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/differentFilename.fir.kt b/compiler/testData/diagnostics/tests/j+k/differentFilename.fir.kt
new file mode 100644
index 00000000000..b0ae18cce3c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/differentFilename.fir.kt
@@ -0,0 +1,26 @@
+// JAVAC_SKIP
+// FILE: A.java
+public class A {
+    public B b() {}
+    public F f() {}
+}
+
+class B { public void bar() {} }
+
+// FILE: C.java
+class D {
+    public void baz() {}
+}
+
+// FILE: E.java
+class F {
+    public void foobaz() {}
+}
+
+// FILE: main.kt
+fun main(x: A) {
+    x.b().<!UNRESOLVED_REFERENCE!>bar<!>()
+    x.f().<!UNRESOLVED_REFERENCE!>foobaz<!>()
+
+    <!UNRESOLVED_REFERENCE!>D<!>().<!UNRESOLVED_REFERENCE!>baz<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/enumGetOrdinal.fir.kt b/compiler/testData/diagnostics/tests/j+k/enumGetOrdinal.fir.kt
new file mode 100644
index 00000000000..e5f13b1d851
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/enumGetOrdinal.fir.kt
@@ -0,0 +1,12 @@
+// FILE: MyEnum.java
+
+public enum MyEnum {
+    A;
+    public int getOrdinal() {return "";}
+}
+
+// FILE: main.kt
+
+fun foo() {
+    MyEnum.A.getOrdinal()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/exceptionMessage.fir.kt b/compiler/testData/diagnostics/tests/j+k/exceptionMessage.fir.kt
new file mode 100644
index 00000000000..cbc8640a180
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/exceptionMessage.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// JAVAC_EXPECTED_FILE
+// FILE: VcsException.java
+import org.jetbrains.annotations.NotNull;
+
+public class VcsException extends Exception {
+    @Override
+    @NotNull
+    public String getMessage() {
+        return "";
+    }
+}
+
+// FILE: main.kt
+fun foo(e: VcsException) {
+    e.message.contains("")
+    "" in e.message
+}
+
+public operator fun CharSequence.contains(other: CharSequence): Boolean = true
diff --git a/compiler/testData/diagnostics/tests/j+k/fieldOverridesField.fir.kt b/compiler/testData/diagnostics/tests/j+k/fieldOverridesField.fir.kt
new file mode 100644
index 00000000000..54d5f50f599
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/fieldOverridesField.fir.kt
@@ -0,0 +1,17 @@
+// FILE: A.java
+
+public class A {
+    public int size = 1;
+}
+
+// FILE: B.java
+
+public class B implements A {
+    public int size = 1;
+}
+
+// FILE: main.kt
+
+fun foo() {
+    B().<!AMBIGUITY!>size<!>
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/fieldOverridesFieldOfDifferentType.fir.kt b/compiler/testData/diagnostics/tests/j+k/fieldOverridesFieldOfDifferentType.fir.kt
new file mode 100644
index 00000000000..d3ba6713d79
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/fieldOverridesFieldOfDifferentType.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+
+// FILE: A.java
+
+public class A {
+    public int size = 1;
+}
+
+// FILE: B.java
+
+public class B extends A {
+    public String size = 1;
+}
+
+// FILE: main.kt
+
+fun foo() {
+    B().<!AMBIGUITY!>size<!>.<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/fieldOverridesNothing.fir.kt b/compiler/testData/diagnostics/tests/j+k/fieldOverridesNothing.fir.kt
new file mode 100644
index 00000000000..b5fc8ab03da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/fieldOverridesNothing.fir.kt
@@ -0,0 +1,19 @@
+// FILE: B.java
+
+public abstract class B implements A {
+    public int size = 1;
+}
+
+// FILE: main.kt
+
+interface A {
+    val size: Int
+}
+
+class C : B() {
+    override val size: Int get() = 1
+}
+
+fun foo() {
+    C().<!AMBIGUITY!>size<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/finalCollectionSize.fir.kt b/compiler/testData/diagnostics/tests/j+k/finalCollectionSize.fir.kt
new file mode 100644
index 00000000000..8eba11c0bc3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/finalCollectionSize.fir.kt
@@ -0,0 +1,12 @@
+// JAVAC_EXPECTED_FILE
+// FILE: A.java
+
+abstract public class A extends java.util.ArrayList<String> {
+    public final int size() { return 0; }
+}
+
+// FILE: main.kt
+
+class B : A() {
+    override val size: Int = 1
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/flexibleNothing.fir.kt b/compiler/testData/diagnostics/tests/j+k/flexibleNothing.fir.kt
new file mode 100644
index 00000000000..942b41dd65c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/flexibleNothing.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+
+// FILE: TestClass.java
+import org.jetbrains.annotations.Nullable;
+public class TestClass {
+    public <T> T set(@Nullable String key, @Nullable T t) {
+        return t;
+    }
+}
+
+// FILE: main.kt
+fun run() {
+    val testClass = TestClass()
+    // inferred as `set<Nothing>()`, return type is Nothing!
+    testClass.set("test", null)
+
+    // Should not be unreachable
+    run()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/classTypeParameterInferredFromArgument.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/classTypeParameterInferredFromArgument.fir.kt
new file mode 100644
index 00000000000..bab46b386aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/classTypeParameterInferredFromArgument.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// FILE: A.java
+
+public class A<E> {
+    public <T extends E> A(E x, java.util.List<T> y) {}
+}
+
+// FILE: main.kt
+
+fun test(x: List<Int>, y: List<String>) {
+    A("", x) checkType { <!UNRESOLVED_REFERENCE!>_<!><A<Any?>>() }
+    A("", y) checkType { <!UNRESOLVED_REFERENCE!>_<!><A<String?>>() }
+
+    <!INAPPLICABLE_CANDIDATE!>A<!><CharSequence, String>("", x)
+    A<CharSequence, String>("", y)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/innerClass.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/innerClass.fir.kt
new file mode 100644
index 00000000000..7dc1379b776
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/innerClass.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// FILE: Outer.java
+
+public class Outer<T> {
+    public class Inner<E> {
+        public <F extends E, G extends T> Inner(E x, java.util.List<F> y, G z) {}
+    }
+}
+
+// FILE: main.kt
+fun test(x: List<Int>, y: List<String>) {
+    Outer<Int>().Inner("", y, 1) checkType { <!UNRESOLVED_REFERENCE!>_<!><Outer<Int>.Inner<String>>() }
+    Outer<Int>().<!INAPPLICABLE_CANDIDATE!>Inner<!><CharSequence, String, Int>("", y, 1) <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Outer<Int>.Inner<CharSequence>>() }
+
+    Outer<Int>().Inner("", x, 1) checkType { <!UNRESOLVED_REFERENCE!>_<!><Outer<Int>.Inner<Any>>() }
+    Outer<Int>().<!INAPPLICABLE_CANDIDATE!>Inner<!><CharSequence, String, Int>("", x, 1)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/noClassTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/noClassTypeParameters.fir.kt
new file mode 100644
index 00000000000..fd33141f842
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/noClassTypeParameters.fir.kt
@@ -0,0 +1,18 @@
+// FILE: A.java
+
+public class A {
+    public <T> A(T x, java.util.List<T> y) {}
+}
+
+// FILE: main.kt
+
+fun test(x: List<Int>, y: List<String>) {
+    A("", x) // inferred as Any!
+    A("", y)
+
+    <!INAPPLICABLE_CANDIDATE!>A<!><String>("", x)
+
+    A<Any>("", x)
+    A<String>("", y)
+    A<CharSequence>("", y)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/noClassTypeParametersInvParameter.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/noClassTypeParametersInvParameter.fir.kt
new file mode 100644
index 00000000000..b2c873d053b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/noClassTypeParametersInvParameter.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// FILE: A.java
+
+public class A {
+    public <T> A(T x, Inv<T> y) {}
+}
+
+// FILE: main.kt
+
+class Inv<T>
+
+fun test(x: Inv<Int>, y: Inv<String>) {
+    <!INAPPLICABLE_CANDIDATE!>A<!>("", x)
+    A("", y)
+
+    <!INAPPLICABLE_CANDIDATE!>A<!><String>("", x)
+
+    <!INAPPLICABLE_CANDIDATE!>A<!><Any>("", x)
+    A<String>("", y)
+    <!INAPPLICABLE_CANDIDATE!>A<!><CharSequence>("", y)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/recursive.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/recursive.fir.kt
new file mode 100644
index 00000000000..d6fae89aa4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/recursive.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// FILE: C.java
+
+// See KT-10410
+public class C {
+    public <T extends T> C(T t) {
+    }
+}
+
+// FILE: main.kt
+
+fun foo() = <!INAPPLICABLE_CANDIDATE!>C<!>()
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/selfTypes.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/selfTypes.fir.kt
new file mode 100644
index 00000000000..b63283686ce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/selfTypes.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: R.java
+public class R<T extends R<T>> {
+    public <F extends R<F>> R(F x) {
+    }
+}
+
+// FILE: RImpl.java
+public class RImpl extends R<RImpl> {
+    public RImpl() {
+        <RImpl>super(null);
+    }
+}
+
+// FILE: main.kt
+fun test() {
+    val x: R<RImpl> = R(RImpl())
+    R<RImpl, RImpl>(RImpl())
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/superCall.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/superCall.fir.kt
new file mode 100644
index 00000000000..660e860c347
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/superCall.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// FILE: A.java
+
+public class A<E> {
+    public <T extends E> A(E x, java.util.List<T> y) {}
+}
+
+// FILE: main.kt
+
+class B1(x: List<String>) : A<CharSequence>("", x)
+class B2(x: List<Int>) : <!INAPPLICABLE_CANDIDATE!>A<CharSequence><!>("", x)
+
+class C : A<CharSequence> {
+    constructor(x: List<String>) : <!INAPPLICABLE_CANDIDATE!>super<!>("", x)
+    constructor(x: List<Int>, y: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>("", x)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/superCallImpossibleToInfer.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/superCallImpossibleToInfer.fir.kt
new file mode 100644
index 00000000000..ce346602671
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/superCallImpossibleToInfer.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// FILE: A.java
+
+public class A<E> {
+    public <T extends E, Q> A(E x, java.util.List<E> y) {}
+}
+
+// FILE: main.kt
+
+// TODO: It's effectively impossible to perform super call to such constructor
+// if there is not enough information to infer corresponding arguments
+// May be we could add some special syntax for such arguments
+class B1(x: List<String>) : A<CharSequence>("", x)
+class B2(x: List<Int>) : <!INAPPLICABLE_CANDIDATE!>A<CharSequence><!>("", x)
+
+class C : A<CharSequence> {
+    constructor(x: List<String>) : <!INAPPLICABLE_CANDIDATE!>super<!>("", x)
+    constructor(x: List<Int>, y: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>("", x)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructor/withClassTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructor/withClassTypeParameters.fir.kt
new file mode 100644
index 00000000000..4ff0ddd0b6e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructor/withClassTypeParameters.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VALUE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+// FILE: A.java
+
+public class A<E> {
+    public <T> A(T x, java.util.List<T> y) {}
+}
+
+// FILE: main.kt
+
+fun test(x: List<Int>, y: List<String>) {
+    var z: A<Double> = A("", x) // E inferred from expected type
+    z = A("", y)
+
+    z = <!INAPPLICABLE_CANDIDATE!>A<!><Double, String>("", x)
+
+    z = A<Double, Any>("", x)
+    z = A<Double, String>("", y)
+    z = A<Double, CharSequence>("", y)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/genericConstructorWithMultipleBounds.fir.kt b/compiler/testData/diagnostics/tests/j+k/genericConstructorWithMultipleBounds.fir.kt
new file mode 100644
index 00000000000..dc79ff1dce8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/genericConstructorWithMultipleBounds.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import java.io.Serializable;
+
+public class J {
+    public <T extends Cloneable & Serializable> J(T t) {}
+}
+
+// FILE: K.kt
+
+import java.io.Serializable
+
+fun cloneable(c: Cloneable) = <!INAPPLICABLE_CANDIDATE!>J<!>(c)
+
+fun serializable(s: Serializable) = <!INAPPLICABLE_CANDIDATE!>J<!>(s)
+
+fun <T> both(t: T) where T : Cloneable, T : Serializable = J(t)
diff --git a/compiler/testData/diagnostics/tests/j+k/inheritAbstractSamAdapter.fir.kt b/compiler/testData/diagnostics/tests/j+k/inheritAbstractSamAdapter.fir.kt
new file mode 100644
index 00000000000..7ddceb7a976
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/inheritAbstractSamAdapter.fir.kt
@@ -0,0 +1,18 @@
+// FILE: A.java
+public interface A {
+    void foo(Runnable r);
+}
+
+// FILE: B.java
+public interface B extends A {
+    public void bar(Runnable r);
+}
+
+// FILE: test.kt
+class C: B {
+    override fun foo(r: Runnable?) {
+    }
+
+    override fun bar(r: Runnable?) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/inheritanceStaticMethodFromInterface.fir.kt b/compiler/testData/diagnostics/tests/j+k/inheritanceStaticMethodFromInterface.fir.kt
new file mode 100644
index 00000000000..f1bfbab902d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/inheritanceStaticMethodFromInterface.fir.kt
@@ -0,0 +1,32 @@
+// FILE: I.java
+
+public interface I {
+    int a = 1;
+    static void foo() {}
+}
+
+// FILE: C.java
+
+public class C implements I {
+    static int b = 1;
+    static void bar() {}
+}
+
+// FILE: test.kt
+
+class K : C()
+
+fun main() {
+    I.a
+    I.foo()
+
+    C.a
+    C.b
+    C.foo()
+    C.bar()
+
+    K.a
+    K.b
+    K.foo()
+    K.bar()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/innerNestedClassFromJava.fir.kt b/compiler/testData/diagnostics/tests/j+k/innerNestedClassFromJava.fir.kt
new file mode 100644
index 00000000000..22576156bde
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/innerNestedClassFromJava.fir.kt
@@ -0,0 +1,32 @@
+// FILE: a/M.java
+package a;
+
+public class M {
+    public class Inner {
+
+    }
+
+    public static class Nested {
+
+    }
+
+    private class PrInner {
+
+    }
+
+    private static class PrNested {
+
+    }
+}
+
+// FILE: b.kt
+package b
+
+fun f() {
+  val c1: a.M.Inner
+  val c2: a.M.Nested
+  val c3: a.M.PrInner
+  val c4: a.M.PrNested
+
+}
+
diff --git a/compiler/testData/diagnostics/tests/j+k/invisiblePackagePrivateInheritedMember.fir.kt b/compiler/testData/diagnostics/tests/j+k/invisiblePackagePrivateInheritedMember.fir.kt
new file mode 100644
index 00000000000..99645d5127a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/invisiblePackagePrivateInheritedMember.fir.kt
@@ -0,0 +1,23 @@
+// FILE: a/M.java
+package a;
+
+public class M {
+    int m;
+}
+
+// FILE: b/F.java
+package b;
+
+import a.M;
+
+public class F extends M {
+}
+
+// FILE: c.kt
+package c
+
+import b.F
+
+fun f() {
+    F().<!INAPPLICABLE_CANDIDATE!>m<!>
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/javaStaticImport.fir.kt b/compiler/testData/diagnostics/tests/j+k/javaStaticImport.fir.kt
new file mode 100644
index 00000000000..72f4f0629bd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/javaStaticImport.fir.kt
@@ -0,0 +1,37 @@
+// JAVAC_EXPECTED_FILE
+// FILE: backend/asmutil/AsmUtil.java
+package backend.asmutil;
+
+import org.jetbrains.annotations.NotNull;
+import static frontend.JvmDeclarationOrigin.NO_ORIGIN;
+
+public class AsmUtil {
+
+    @NotNull
+    public static String doSmth(String s) {
+        Object or = NO_ORIGIN;
+        return "OK";
+    }
+}
+
+// FILE: First.kt
+package frontend
+public class JvmDeclarationOrigin {
+    companion object {
+        public val NO_ORIGIN: JvmDeclarationOrigin = JvmDeclarationOrigin()
+    }
+}
+
+// FILE: Second.kt
+package backend
+
+import backend.asmutil.AsmUtil.doSmth
+
+open public class ECallable  {
+    fun test() {
+        doSmth("")
+    }
+}
+
+/* KT-5848 */
+
diff --git a/compiler/testData/diagnostics/tests/j+k/kt1402.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt1402.fir.kt
new file mode 100644
index 00000000000..40e71ec651e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt1402.fir.kt
@@ -0,0 +1,26 @@
+// FILE: a/M.java
+package a;
+
+public class M {
+    public static class Inner {
+        private int i;
+        public Inner(int i) {
+            this.i = i;
+        }
+
+        public int getI() {
+            return i;
+        }
+    }
+}
+
+// FILE: b.kt
+package b
+
+import a.M.Inner
+
+fun foo() {
+    doSmth(Inner(87))
+}
+
+fun doSmth(b: Inner) = b
diff --git a/compiler/testData/diagnostics/tests/j+k/kt1431.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt1431.fir.kt
new file mode 100644
index 00000000000..971257ededc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt1431.fir.kt
@@ -0,0 +1,17 @@
+//FILE: a/C.java
+// KT-1431 StackOverflowException in IDE when using JavaFX builders
+package a;
+
+public class C<B extends C<B>> {
+    public static C<?> create() { return null; }
+    public C foo() {return null;}
+}
+
+//FILE: d.kt
+package d
+
+import a.C
+
+fun test() {
+    C.create().foo()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/kt1730_implementCharSequence.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt1730_implementCharSequence.fir.kt
new file mode 100644
index 00000000000..7efe604a0e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt1730_implementCharSequence.fir.kt
@@ -0,0 +1,24 @@
+// KT-1730 Method which has been implemented by Java is recognized to be abstract.
+
+// FILE: C.java
+public class C implements java.lang.CharSequence {
+    @Override
+    public int length() {
+        return 3;
+    }
+    @Override
+    public char charAt(int index) {
+        return 48;
+    }
+    @Override
+    public CharSequence subSequence(int start, int end) {
+        return "ab";
+    }
+    @Override
+    public String toString() {
+        return "abc";
+    }
+}
+
+// FILE: T.kt
+class T : C()
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2152.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2152.fir.kt
new file mode 100644
index 00000000000..113ca5b4bb7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt2152.fir.kt
@@ -0,0 +1,10 @@
+//FILE: Bbb.kt
+open class Bbb
+
+//FILE: Ccc.java
+public class Ccc extends Bbb {
+}
+
+//FILE: Ddd.kt
+import Ccc
+
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2394.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2394.fir.kt
new file mode 100644
index 00000000000..877f140f272
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt2394.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+//KT-2394 java.lang.Iterable<T> should be visible as kotlin.Iterable<out T>
+package d
+
+fun foo(iterable: Iterable<Int>, iterator: Iterator<Int>, comparable: Comparable<Any>) {
+    checkSubtype<Iterable<Any>>(iterable)
+    checkSubtype<Iterator<Any>>(iterator)
+    checkSubtype<Comparable<String>>(comparable)
+}
+
+fun bar(c: Collection<Int>) {
+    checkSubtype<Iterable<Any>>(c)
+    checkSubtype<Iterator<Any>>(c.iterator())
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2606.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2606.fir.kt
new file mode 100644
index 00000000000..f362ec33d42
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt2606.fir.kt
@@ -0,0 +1,11 @@
+//KT-2606 Filter java.util.* import
+package n
+
+import java.util.*
+import java.lang.annotation.*
+
+fun bar() : Iterator<Int>? {
+    val i : Iterable<Integer>
+    val a : Annotation
+    return null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2619.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2619.fir.kt
new file mode 100644
index 00000000000..9613d6f02fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt2619.fir.kt
@@ -0,0 +1,15 @@
+//FILE: foo.kt
+fun main() {
+    val c: Type
+    when (c)  {
+
+    }
+}
+
+
+
+//FILE: Type.java
+public enum Type {
+    TYPE,
+    NO_TYPE;
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2641.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2641.fir.kt
new file mode 100644
index 00000000000..ea101ae4fc6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt2641.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+package a
+
+import java.util.Iterator
+import java.lang.Comparable as Comp
+
+fun bar(any: Any): java.lang.Iterable<Int>? {
+    val a: java.lang.Comparable<String>? = null
+    val b: Iterable<Integer>
+    val c : Iterator<String>? = null
+
+    if (any is Iterator<*>) {
+        checkSubtype<Iterator<*>>(any)
+    }
+    any as Iterator<*>
+    return null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2890.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2890.fir.kt
new file mode 100644
index 00000000000..c8d0830ef06
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt2890.fir.kt
@@ -0,0 +1,20 @@
+//FILE:_03_collections/CollectionTest.java
+package _03_collections;
+
+import java.util.List;
+
+public class CollectionTest {
+    public static void add(List<Integer> ints) {
+        ints.add(5);
+    }
+}
+
+//FILE:n.kt
+package _03_collections
+
+import java.util.ArrayList
+
+fun test() {
+  val c = CollectionTest()
+  CollectionTest.add(ArrayList())
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/kt3307.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt3307.fir.kt
new file mode 100644
index 00000000000..340842481bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt3307.fir.kt
@@ -0,0 +1,21 @@
+// FILE: Bug.java
+
+public interface Bug {
+        <RET extends Bug> RET save();
+}
+
+// FILE: SubBug.java
+
+public class SubBug implements Bug {
+        public SubBug save() {
+                return this;
+        }
+}
+
+// FILE: Bug.kt
+
+fun TestBug() {
+   SubBug().save() // can resolve on subtype
+   val bug: Bug = SubBug()
+   bug.save<Bug>() // can resolve on supertype
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/kt3311.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt3311.fir.kt
new file mode 100644
index 00000000000..080e29b9e9b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt3311.fir.kt
@@ -0,0 +1,19 @@
+// FILE: Super.java
+public class Super {
+    public boolean foo;
+    public boolean bar;
+
+    public void setFoo(boolean foo) {
+        this.foo = foo;
+    }
+}
+
+// FILE: b.kt
+public class Sub: Super() {
+}
+
+fun main() {
+    val x = Sub()
+    x.foo = true
+    x.bar = true
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/kt6720_abstractProperty.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt6720_abstractProperty.fir.kt
new file mode 100644
index 00000000000..988e5ec6549
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt6720_abstractProperty.fir.kt
@@ -0,0 +1,18 @@
+// FILE: AC.kt
+
+interface A {
+    val a: Int
+}
+
+// FILE: B.java
+
+public abstract class B implements A {
+}
+
+// FILE: C.kt
+
+class C : B()
+
+fun main() {
+    C().a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/kt7523.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt7523.fir.kt
new file mode 100644
index 00000000000..64e8ab34bc1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/kt7523.fir.kt
@@ -0,0 +1,14 @@
+// FILE: A.java
+public interface A<T extends A<? super T, ?>, S extends A<? super T, ?>> {}
+
+// FILE: C.java
+public class C
+{
+    public <T extends A<? super T, ?>, S extends A<? super T, ?>> void f(A<T, S> x){}
+}
+
+// FILE: main.kt
+fun foo() {
+    // TODO: uncomment when KT-9597 is fixed
+    // C().f(object : A<*, *> {})
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/matchers.fir.kt b/compiler/testData/diagnostics/tests/j+k/matchers.fir.kt
new file mode 100644
index 00000000000..4c2bcb72eef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/matchers.fir.kt
@@ -0,0 +1,18 @@
+// FILE: Assert.java
+
+public class Assert {
+    public static <T> void assertThat(T actual, Matcher<? super T> matcher) {
+    }
+}
+
+// FILE: Matcher.java
+public class Matcher<T> {
+    public static <T> Matcher<java.lang.Iterable<? super T>> hasItem(T item) {
+        return null;
+    }
+}
+
+// FILE: main.kt
+fun test(x: List<String>) {
+    Assert.<!INAPPLICABLE_CANDIDATE!>assertThat<!>(x, Matcher.hasItem("abc"))
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/mutableIterator.fir.kt b/compiler/testData/diagnostics/tests/j+k/mutableIterator.fir.kt
new file mode 100644
index 00000000000..9f24f78c48c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/mutableIterator.fir.kt
@@ -0,0 +1,29 @@
+//FILE:a/JC.java
+package a;
+
+import java.util.Iterator;
+
+public interface JC<T> {
+    public Iterator<T> getIterator();
+
+    public void setIterator(Iterator<T> iterator);
+
+    public Iterable<T> getIterable();
+
+    public void setIterable(Iterable<T> iterable);
+}
+
+//FILE:n.kt
+package n
+
+import a.JC
+
+fun foo(c: JC<Int>, iterator: Iterator<Int>, iterable: Iterable<Int>) {
+    val mutableIterator: MutableIterator<Int>? = c.getIterator()
+    c.setIterator(mutableIterator)
+    c.setIterator(iterator)
+
+    val mutableIterable: MutableIterable<Int>? = c.getIterable()
+    c.setIterable(mutableIterable)
+    c.setIterable(iterable)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/nullForOptionalOrElse.fir.kt b/compiler/testData/diagnostics/tests/j+k/nullForOptionalOrElse.fir.kt
new file mode 100644
index 00000000000..b3ac1902278
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/nullForOptionalOrElse.fir.kt
@@ -0,0 +1,9 @@
+// FULL_JDK
+
+import java.util.*
+import java.util.stream.Stream
+
+fun <T> Stream<T>?.getIfSingle() =
+        this?.map { Optional.ofNullable(it) }
+        ?.reduce(Optional.empty()) { _, _ -> Optional.empty() }
+        ?.orElse(null) // <<---- should not be an error
diff --git a/compiler/testData/diagnostics/tests/j+k/overrideRawType.fir.kt b/compiler/testData/diagnostics/tests/j+k/overrideRawType.fir.kt
new file mode 100644
index 00000000000..4772e9a77c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/overrideRawType.fir.kt
@@ -0,0 +1,15 @@
+//FILE: Foo.java
+public class Foo<T extends CharSequence> {
+}
+
+//FILE: Bar.java
+public interface Bar {
+    void f(Foo f);
+}
+
+//FILE: a.kt
+class BarImpl: Bar {
+    override fun f(f: Foo<*>?) {
+        throw UnsupportedOperationException()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/overrideWithSamAndTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/j+k/overrideWithSamAndTypeParameter.fir.kt
new file mode 100644
index 00000000000..8ce4c73cbd9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/overrideWithSamAndTypeParameter.fir.kt
@@ -0,0 +1,22 @@
+// FILE: MyFunc.java
+
+public interface MyFunc {
+    String apply(String x);
+}
+
+// FILE: A.java
+public interface A<K> {
+    K foo(K key, MyFunc f);
+}
+
+// FILE: B.java
+public class B<E> implements A<E> {
+    @Override
+    public E foo(E key, MyFunc f) {return null;}
+}
+
+// FILE: main.kt
+
+fun main() {
+    B<String>().foo("") { "" }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/packagePrivateClassStaticMember.fir.kt b/compiler/testData/diagnostics/tests/j+k/packagePrivateClassStaticMember.fir.kt
new file mode 100644
index 00000000000..b93b076994c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/packagePrivateClassStaticMember.fir.kt
@@ -0,0 +1,17 @@
+// KT-4021 Java's Package visibilty does not work for static methods
+
+// FILE: foo/Bar.java
+
+package foo;
+
+class Bar {
+    static void baz() {}
+}
+
+// FILE: main.kt
+
+package foo
+
+fun main() {
+    Bar.baz()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/packageVisibility.fir.kt b/compiler/testData/diagnostics/tests/j+k/packageVisibility.fir.kt
new file mode 100644
index 00000000000..ff2aed7313b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/packageVisibility.fir.kt
@@ -0,0 +1,44 @@
+//FILE: a/MyJavaClass.java
+package a;
+
+class MyJavaClass {
+    static int staticMethod() {
+        return 1;
+    }
+
+    static class NestedClass {
+        static int staticMethodOfNested() {
+            return 1;
+        }
+    }
+}
+
+//FILE:a.kt
+package a
+
+val mc = MyJavaClass()
+val x = MyJavaClass.staticMethod()
+val y = MyJavaClass.NestedClass.staticMethodOfNested()
+val z = MyJavaClass.NestedClass()
+
+//FILE: b.kt
+package b
+
+import a.MyJavaClass
+
+val mc1 = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>()
+
+val x = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>.<!UNRESOLVED_REFERENCE!>staticMethod<!>()
+val y = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>.<!UNRESOLVED_REFERENCE!>NestedClass<!>.<!UNRESOLVED_REFERENCE!>staticMethodOfNested<!>()
+val z = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>.<!UNRESOLVED_REFERENCE!>NestedClass<!>()
+
+//FILE: c.kt
+package a.c
+
+import a.MyJavaClass
+
+val mc1 = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>()
+
+val x = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>.<!UNRESOLVED_REFERENCE!>staticMethod<!>()
+val y = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>.<!UNRESOLVED_REFERENCE!>NestedClass<!>.<!UNRESOLVED_REFERENCE!>staticMethodOfNested<!>()
+val z = <!INAPPLICABLE_CANDIDATE!>MyJavaClass<!>.<!UNRESOLVED_REFERENCE!>NestedClass<!>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/kt11140.fir.kt b/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/kt11140.fir.kt
new file mode 100644
index 00000000000..8adec367303
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/kt11140.fir.kt
@@ -0,0 +1,24 @@
+// JAVAC_EXPECTED_FILE
+// FILE: B.java
+public interface B<T1, T2> {
+    double put(int x, double y);
+    T2 put(T1 x, T2 y);
+}
+// FILE: A.java
+import java.util.HashMap;
+
+public class A extends HashMap<Integer, Double> implements B<Integer, Double> {
+    public double put(int x, double y) {
+        return 1.0;
+    }
+
+    @Override
+    public Double put(Integer key, Double value) {
+        return super.put(key, value);
+    }
+}
+// FILE: main.kt
+fun test(){
+    val o = A()
+    o.<!AMBIGUITY!>put<!>(1, 2.0)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/notNullAnnotated.fir.kt b/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/notNullAnnotated.fir.kt
new file mode 100644
index 00000000000..1a501bd20ef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/notNullAnnotated.fir.kt
@@ -0,0 +1,22 @@
+// FILE: A.java
+import org.jetbrains.annotations.*;
+
+public class A {
+    public void foo(int x) {}
+    public void bar(@NotNull Double x) {}
+}
+
+// FILE: B.java
+import org.jetbrains.annotations.*;
+public class B extends A {
+    public void foo(@NotNull Integer x) {}
+    public void bar(double x) {}
+}
+
+// FILE: main.kt
+
+fun foo(b: B) {
+    // See KT-9182
+    b.foo(1)
+    b.bar(2.0)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/specializedMap.fir.kt b/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/specializedMap.fir.kt
new file mode 100644
index 00000000000..dad78e433d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/primitiveOverrides/specializedMap.fir.kt
@@ -0,0 +1,113 @@
+// FILE: AbstractSpecializedMap.java
+public abstract class AbstractSpecializedMap implements java.util.Map<Integer, Double> {
+    public abstract double put(int x, double y);
+    public abstract double remove(int k);
+    public abstract double get(int k);
+
+    public abstract boolean containsKey(int k);
+    public boolean containsKey(Object x) {
+        return false;
+    }
+
+    public abstract boolean containsValue(double v);
+    public boolean containsValue(Object x) {
+        return false;
+    }
+}
+
+// FILE: SpecializedMap.java
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Collection;
+import java.util.Map;
+import java.util.Set;
+
+public class SpecializedMap extends AbstractSpecializedMap {
+    public double put(int x, double y) {
+        return 123.0;
+    }
+
+    @Override
+    public Double get(Object key) {
+        return null;
+    }
+
+    @Override
+    public Double put(Integer key, Double value) {
+        return null;
+    }
+
+    public double remove(int k) {
+        return 456.0;
+    }
+
+
+    public Double remove(Object ok) {
+        return null;
+    }
+
+
+    public double get(int k) {
+        return 789.0;
+    }
+
+    public boolean containsKey(int k) {
+        return true;
+    }
+
+    public boolean containsValue(double v) {
+        return true;
+    }
+
+    @Override
+    public void putAll(Map<? extends Integer, ? extends Double> m) {
+    }
+
+    @Override
+    public void clear() {
+
+    }
+
+    @NotNull
+    @Override
+    public Set<Integer> keySet() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Collection<Double> values() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Set<Entry<Integer, Double>> entrySet() {
+        return null;
+    }
+
+    @Override
+    public int size() {
+        return 0;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return false;
+    }
+}
+
+// FILE: main.kt
+fun foo(x: SpecializedMap) {
+    x.containsKey(1)
+    x.containsKey(null)
+
+    x.get(2)
+    x.get(null)
+
+    x.remove(3)
+    x.remove(null)
+
+    x.<!AMBIGUITY!>put<!>(4, 5.0)
+    x.<!AMBIGUITY!>put<!>(4, null)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/primitiveOverridesWithInlineClass/inlineClassErasedToPrimitiveInt.fir.kt b/compiler/testData/diagnostics/tests/j+k/primitiveOverridesWithInlineClass/inlineClassErasedToPrimitiveInt.fir.kt
new file mode 100644
index 00000000000..c4ff078edd2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/primitiveOverridesWithInlineClass/inlineClassErasedToPrimitiveInt.fir.kt
@@ -0,0 +1,29 @@
+// !LANGUAGE: +InlineClasses
+// FILE: kt1.kt
+package kt
+
+inline class Z(val value: Int)
+
+interface IFoo<T> {
+    fun foo(): T
+}
+
+open class KFooZ : IFoo<Z> {
+    override fun foo(): Z = Z(42)
+}
+
+// FILE: j/J.java
+package j;
+
+import kt.Z;
+import kt.KFooZ;
+
+public class J extends KFooZ {
+}
+
+// FILE: kt2.kt
+package kt
+
+import j.J
+
+fun jfoo(x: J) = x.foo()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/privateFieldOverridesNothing.fir.kt b/compiler/testData/diagnostics/tests/j+k/privateFieldOverridesNothing.fir.kt
new file mode 100644
index 00000000000..56516cd67e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/privateFieldOverridesNothing.fir.kt
@@ -0,0 +1,19 @@
+// FILE: B.java
+
+public abstract class B implements A {
+    private int size = 1;
+}
+
+// FILE: main.kt
+
+interface A {
+    val size: Int
+}
+
+class C : B() {
+    override val size: Int get() = 1
+}
+
+fun foo() {
+    C().size 
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/privateNestedClassStaticMember.fir.kt b/compiler/testData/diagnostics/tests/j+k/privateNestedClassStaticMember.fir.kt
new file mode 100644
index 00000000000..d0a40b6be97
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/privateNestedClassStaticMember.fir.kt
@@ -0,0 +1,18 @@
+// KT-4149 static members of Java private nested class are accessible from Kotlin
+
+// FILE: javaPackage/Foo.java
+
+package javaPackage;
+
+public class Foo {
+    private static class Bar {
+        public static void doSmth() {
+        }
+    }
+}
+
+// FILE: 1.kt
+
+fun main() {
+    javaPackage.Foo.Bar.doSmth()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/properties/interface.fir.kt b/compiler/testData/diagnostics/tests/j+k/properties/interface.fir.kt
new file mode 100644
index 00000000000..7c3c81e57f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/properties/interface.fir.kt
@@ -0,0 +1,32 @@
+// FILE: A.java
+
+public interface A extends B {
+    public int getFoo();
+    public void setFoo(int x);
+}
+
+// FILE: BImpl.java
+
+public class BImpl implements B {
+    public int getFoo() {}
+    public void setFoo(int x) {}
+}
+
+// FILE: main.kt
+
+interface B {
+    var foo: Int
+}
+
+interface C1 : A {
+    override var foo: Int
+}
+
+class D : C1, BImpl()
+
+fun foo() {
+    BImpl().foo = BImpl().foo + 1
+    D().foo = D().foo + 2
+}
+
+
diff --git a/compiler/testData/diagnostics/tests/j+k/properties/isName.fir.kt b/compiler/testData/diagnostics/tests/j+k/properties/isName.fir.kt
new file mode 100644
index 00000000000..3e86adc7ca0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/properties/isName.fir.kt
@@ -0,0 +1,27 @@
+// FILE: A.java
+
+public class A extends B {
+    public int isFoo() { return 0; }
+    public void setFoo(int x) {}
+}
+
+// FILE: F.java
+
+public class F extends B {
+    public final int isFoo() { return 0; }
+    public final void setFoo(int x) {}
+}
+
+// FILE: main.kt
+
+open class B {
+    open var isFoo: Int = 1
+}
+
+class C1 : A() {
+    override var isFoo: Int = 2
+}
+
+class C2 : F() {
+    override var isFoo: Int = 3
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/properties/val.fir.kt b/compiler/testData/diagnostics/tests/j+k/properties/val.fir.kt
new file mode 100644
index 00000000000..63aa0476c5d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/properties/val.fir.kt
@@ -0,0 +1,25 @@
+// FILE: A.java
+
+public class A extends B {
+    public int getFoo() { return 0; }
+}
+
+// FILE: F.java
+
+public class F extends B {
+    public final int getFoo() { return 0; }
+}
+
+// FILE: main.kt
+
+open class B {
+    open val foo: Int = 1
+}
+
+class C1 : A() {
+    override val foo: Int = 2
+}
+
+class C2 : F() {
+    override val foo: Int = 3
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/properties/var.fir.kt b/compiler/testData/diagnostics/tests/j+k/properties/var.fir.kt
new file mode 100644
index 00000000000..41e5c92ff12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/properties/var.fir.kt
@@ -0,0 +1,42 @@
+// FILE: A.java
+
+public class A extends B {
+    public int getFoo() { return 0; }
+    public void setFoo(int x) {}
+}
+
+// FILE: F.java
+
+public class F extends B {
+    public final int getFoo() { return 0; }
+    public final void setFoo(int x) {}
+}
+
+// FILE: ConflictingModality.java
+
+public class ConflictingModality extends B {
+    public final int getFoo() { return 0; }
+    public abstract void setFoo(int x) {}
+}
+
+// FILE: ConflictingVisibility.java
+
+public class ConflictingVisibility extends B {
+    public int getFoo() { return 0; }
+    protected void setFoo(int x) {}
+}
+
+// FILE: main.kt
+
+open class B {
+    // check that final is not overridden
+    open protected var foo: Int = 1
+}
+
+class C1 : A() {
+    override var foo: Int = 2
+}
+
+class C2 : F() {
+    override var foo: Int = 3
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/protectedStaticSamePackage.fir.kt b/compiler/testData/diagnostics/tests/j+k/protectedStaticSamePackage.fir.kt
new file mode 100644
index 00000000000..e51d7bc5689
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/protectedStaticSamePackage.fir.kt
@@ -0,0 +1,20 @@
+// FILE: test/JavaClass.java
+
+package test;
+
+public class JavaClass {
+    protected static int field;
+
+    protected static String method() {
+        return "";
+    }
+}
+
+// FILE: test.kt
+
+package test
+
+fun test() {
+    JavaClass.field
+    JavaClass.method()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/recursionWithJavaSyntheticProperty.fir.kt b/compiler/testData/diagnostics/tests/j+k/recursionWithJavaSyntheticProperty.fir.kt
new file mode 100644
index 00000000000..875fa382fa8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/recursionWithJavaSyntheticProperty.fir.kt
@@ -0,0 +1,12 @@
+// FILE: X.java
+
+public class X {
+    int getFoo() {return 3;}
+}
+
+// FILE: Usage.kt
+
+class A : X() {
+    // TODO: DEBUG_INFO_MISSING_UNRESOLVED indicates a bug here
+    override fun getFoo() = foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound.fir.kt b/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound.fir.kt
new file mode 100644
index 00000000000..75a5c2333d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound.fir.kt
@@ -0,0 +1,13 @@
+// FILE: Bad.java
+
+public class Bad<T extends Bad> {}
+
+// FILE: X.java
+
+public class X {
+  Bad foo() {return null;}
+}
+
+// FILE: Usage.kt
+
+fun foo(p: X) = p.foo()
diff --git a/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound2.fir.kt b/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound2.fir.kt
new file mode 100644
index 00000000000..dfc3e1205f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound2.fir.kt
@@ -0,0 +1,8 @@
+// FILE: XYZ.java
+public interface XYZ<X extends X> {
+    XYZ foo() {}
+}
+
+// FILE: main.kt
+
+fun main(xyz: XYZ<*>) = xyz.foo()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound3.fir.kt b/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound3.fir.kt
new file mode 100644
index 00000000000..282814ecf53
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/recursiveRawUpperBound3.fir.kt
@@ -0,0 +1,8 @@
+// FILE: XYZ.java
+public interface XYZ<X extends Y, Y extends Z, Z extends Y> {
+    XYZ foo() {}
+}
+
+// FILE: main.kt
+
+fun main(xyz: XYZ<*, *, *>) = xyz.foo()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/enhancedSamConstructor.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/enhancedSamConstructor.fir.kt
new file mode 100644
index 00000000000..8b236b356e7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/enhancedSamConstructor.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+import org.jetbrains.annotations.*;
+
+public interface J {
+    @NotNull
+    String foo(@Nullable String x);
+}
+
+// FILE: J2.java
+import org.jetbrains.annotations.Nullable;
+
+public interface J2 extends J {
+    String foo(String x);
+}
+
+// FILE: main.kt
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>J<!> { s: String -> s} // should be prohibited, because SAM value parameter has nullable type
+    J { "" + it.<!INAPPLICABLE_CANDIDATE!>length<!> }
+    J { null }
+    J { it?.length?.toString() }
+
+    <!INAPPLICABLE_CANDIDATE!>J2<!> { s: String -> s}
+    J2 { "" + it.<!INAPPLICABLE_CANDIDATE!>length<!> }
+    J2 { null }
+    J2 { it?.length?.toString() }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/fakeOverrideFunctionForStaticSam.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/fakeOverrideFunctionForStaticSam.fir.kt
new file mode 100644
index 00000000000..88ae849b8fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/fakeOverrideFunctionForStaticSam.fir.kt
@@ -0,0 +1,20 @@
+// FILE: BehaviorSubject.java
+public class BehaviorSubject<T> extends Observable<T> {
+}
+
+// FILE: Observable.java
+
+public class Observable<T> {
+    public static <T> Observable<T> create(Observable.OnSubscribe<T> f) {
+        return null;
+    }
+    public interface OnSubscribe<T> {
+        void call(T t);
+    }
+}
+
+// FILE: 1.kt
+fun main() {
+    BehaviorSubject.create<String>(null)
+    BehaviorSubject.create<Int> { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/inheritedStaticSam.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/inheritedStaticSam.fir.kt
new file mode 100644
index 00000000000..0779d3ced95
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/inheritedStaticSam.fir.kt
@@ -0,0 +1,13 @@
+// FILE: Statics.java
+
+public class Statics {
+    public static void foo(Runnable r) {}
+}
+
+// FILE: test.kt
+
+class A : Statics() {
+    fun test() {
+        foo {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/privateCandidatesWithWrongArguments.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/privateCandidatesWithWrongArguments.fir.kt
new file mode 100644
index 00000000000..f45fd6988e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/privateCandidatesWithWrongArguments.fir.kt
@@ -0,0 +1,21 @@
+// JAVAC_EXPECTED_FILE
+// FILE: foo/A.java
+package foo;
+
+public class A {
+    static void f(B b) {
+        b.g();
+    }
+
+    public interface B {
+        void g();
+    }
+}
+
+// FILE: bar/sample.kt
+
+package bar
+
+fun main() {
+    foo.A.<!INAPPLICABLE_CANDIDATE!>f<!> {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/recursiveSamsAndInvoke.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/recursiveSamsAndInvoke.fir.kt
new file mode 100644
index 00000000000..6457136dfdd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/recursiveSamsAndInvoke.fir.kt
@@ -0,0 +1,28 @@
+// FILE: MyFuture.java
+
+public interface MyFuture<V> {
+    MyFuture<V> addListener(MyListener<? extends MyFuture<? super V>> listener);
+}
+
+// FILE: MyListener.java
+
+public interface MyListener<F extends MyFuture<?>>  {
+    void operationComplete(F future) throws Exception;
+}
+
+// FILE: test.kt
+
+typealias Handler = (cause: Throwable?) -> Unit
+
+fun <T> MyFuture<T>.setup() {
+    addListener(ListenerImpl<T, MyFuture<T>>())
+    addListener { }
+}
+
+class ListenerImpl<T, F : MyFuture<T>> : MyListener<F>, Handler {
+    override fun operationComplete(future: F) {
+    }
+
+    override fun invoke(cause: Throwable?) {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/samOnTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/samOnTypeParameter.fir.kt
new file mode 100644
index 00000000000..4b32b73471d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/samOnTypeParameter.fir.kt
@@ -0,0 +1,17 @@
+// FILE: FormFieldValidatorPresenterTest.java
+public class FormFieldValidatorPresenterTest<V extends String> {
+
+    public void setValidationListenerTest(ValidationListenerTest validationListener) {
+    }
+
+    public interface ValidationListenerTest {
+        void onValidityChanged(boolean valid);
+    }
+}
+// FILE: main.kt
+fun <P : FormFieldValidatorPresenterTest<String>> setValidationListener(
+        presenter: P,
+        validationListener: (Boolean) -> Unit
+) {
+    presenter.setValidationListenerTest(validationListener) // Error: Type mismatch: inferred type is (Boolean) -> Unit but FormFieldValidatorPresenterTest.ValidationListenerTest! was expected
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/staticSamFromImportWithStar.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/staticSamFromImportWithStar.fir.kt
new file mode 100644
index 00000000000..b299377a168
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/staticSamFromImportWithStar.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a/Statics.java
+
+package a;
+
+public class Statics {
+    public static void foo(Runnable r) {}
+}
+
+// FILE: test.kt
+
+package b
+
+import a.Statics.*
+
+fun test() {
+    foo {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/staticSamWithExplicitImport.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/staticSamWithExplicitImport.fir.kt
new file mode 100644
index 00000000000..8c551eed7b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/staticSamWithExplicitImport.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a/Statics.java
+
+package a;
+
+public class Statics {
+    public static void foo(Runnable r) {}
+}
+
+// FILE: test.kt
+
+package b;
+
+import a.Statics.foo
+
+fun test() {
+    foo {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/typeInferenceOnSamAdapters.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/typeInferenceOnSamAdapters.fir.kt
new file mode 100644
index 00000000000..544d981203a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/typeInferenceOnSamAdapters.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_ANONYMOUS_PARAMETER
+// FILE: A.java
+public class A<K, V> {
+    public void foo(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+
+    }
+}
+
+// FILE: BiFunction.java
+public interface BiFunction<T, U, R> {
+    R apply(T t, U u);
+}
+
+// FILE: main.kt
+fun main() {
+    val a = A<Int, String>()
+    a.foo(2, BiFunction { k, v -> null })
+    a.foo(2) { k, v -> null } // See KT-12144
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/sam/withDefaultMethods.fir.kt b/compiler/testData/diagnostics/tests/j+k/sam/withDefaultMethods.fir.kt
new file mode 100644
index 00000000000..acc211a1064
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/sam/withDefaultMethods.fir.kt
@@ -0,0 +1,22 @@
+// FILE: ALambda.java
+
+public interface ALambda {
+    ALambda curried();
+
+    ALambda tupled();
+}
+
+// FILE: ACheckedFunction0.java
+
+public interface ACheckedFunction0 extends ALambda {
+
+    Integer apply();
+
+    default ALambda curried() { return null; }
+    default ALambda tupled() { return null; }
+}
+
+// FILE: main.kt
+fun test() {
+    ACheckedFunction0 { 2 } // error: Interface ACheckedFunction0 does not have constructors
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericInReturnType.fir.kt b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericInReturnType.fir.kt
new file mode 100644
index 00000000000..1c2ee9979c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericInReturnType.fir.kt
@@ -0,0 +1,53 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// FILE: EventListener.java
+public interface EventListener<E> {
+    E handle(String x);
+}
+
+// FILE: A.java
+public class A {
+    public void foo(EventListener<?> l) {
+    }
+
+    public static void bar(EventListener<?> l) {
+    }
+
+    public static void baz(EventListener<? extends CharSequence> l) {
+    }
+}
+
+// FILE: main.kt
+fun main() {
+    A().foo {
+        x -> x.hashCode()
+    }
+
+    A.bar {
+        x -> x.hashCode()
+    }
+
+
+    // baz
+    A.baz {
+        x -> x.toString() // OK
+    }
+
+    A.baz {
+        x -> x.hashCode()
+    }
+
+    val block: (String) -> Any? = {
+        x -> x.hashCode()
+    }
+
+    A().foo(block)
+    A.bar(block)
+
+    val block2: (String) -> CharSequence? = {
+        x -> x.toString()
+    }
+
+    A.<!INAPPLICABLE_CANDIDATE!>baz<!>(block)
+    A.baz(block2)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericInValueParameter.fir.kt b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericInValueParameter.fir.kt
new file mode 100644
index 00000000000..1da5559f790
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericInValueParameter.fir.kt
@@ -0,0 +1,32 @@
+// !CHECK_TYPE
+// FILE: EventListener.java
+public interface EventListener<E> {
+    void handle(E e);
+}
+
+// FILE: A.java
+public class A {
+    public void foo(EventListener<?> l) {
+    }
+
+    public static void bar(EventListener<?> l) {
+    }
+
+    public static void baz(EventListener<? extends CharSequence> l) {
+    }
+}
+
+// FILE: main.kt
+fun main() {
+    A().foo {
+        x -> x checkType { _<Any?>() }
+    }
+
+    A.bar {
+        x -> x checkType { _<Any?>() }
+    }
+
+    A.baz {
+        x -> x checkType { _<CharSequence?>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericSuperWildcard.fir.kt b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericSuperWildcard.fir.kt
new file mode 100644
index 00000000000..df6128944c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/genericSuperWildcard.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+// FILE: EventListener.java
+public interface EventListener<E> {
+    void handle(E e);
+}
+
+// FILE: A.java
+public class A {
+    public void foo(EventListener<? super CharSequence> l) {
+    }
+
+    public static void bar(EventListener<? super String> l) {
+    }
+}
+
+// FILE: main.kt
+fun main() {
+    A().foo {
+        x -> x checkType { _<CharSequence?>() }
+    }
+
+    A.bar {
+        x -> x checkType { _<String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/samByProjectedType/noAdapterBecuaseOfRecursiveUpperBound.fir.kt b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/noAdapterBecuaseOfRecursiveUpperBound.fir.kt
new file mode 100644
index 00000000000..bff8339f4bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/noAdapterBecuaseOfRecursiveUpperBound.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// FILE: Function.java
+public interface Function<E extends CharSequence, F extends java.util.Map<String, E>> {
+    E handle(F f);
+}
+
+// FILE: A.java
+public class A {
+    public void foo(Function<?, ?> l) {
+    }
+
+    public static void bar(Function<?, ?> l) {
+    }
+}
+
+// FILE: main.kt
+fun main() {
+    A().foo {
+        x ->
+        ""
+    }
+
+    A.bar {
+        x ->
+        ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/samByProjectedType/starProjectionComplexUpperBound.fir.kt b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/starProjectionComplexUpperBound.fir.kt
new file mode 100644
index 00000000000..648e6875297
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/samByProjectedType/starProjectionComplexUpperBound.fir.kt
@@ -0,0 +1,33 @@
+// !CHECK_TYPE
+// FILE: Function.java
+public interface Function<E extends java.util.Map<String, Integer>, F extends CharSequence> {
+    F handle(E e);
+}
+
+// FILE: A.java
+public class A {
+    public void foo(Function<?, ?> l) {
+    }
+
+    public static void bar(Function<?, ?> l) {
+    }
+}
+
+// FILE: main.kt
+fun main() {
+    A().foo {
+        x ->
+        x checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Map<String, Int>?>() }
+        ""
+    }
+
+    A.bar {
+        x ->
+        x checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Map<String, Int>>() }
+        ""
+    }
+
+    val block: (Map<String, Int>) -> CharSequence = { x -> x.toString() }
+    A().<!INAPPLICABLE_CANDIDATE!>foo<!>(block)
+    A.<!INAPPLICABLE_CANDIDATE!>bar<!>(block)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/samInConstructorWithGenerics.fir.kt b/compiler/testData/diagnostics/tests/j+k/samInConstructorWithGenerics.fir.kt
new file mode 100644
index 00000000000..f5a5200958b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/samInConstructorWithGenerics.fir.kt
@@ -0,0 +1,23 @@
+// FILE: j/OnSubscribe.java
+package j;
+
+public interface OnSubscribe<T> {
+    void f();
+}
+
+// FILE: j/Observable.java
+package j;
+
+public class Observable<T> {
+
+    protected Observable(OnSubscribe<T> f) {
+    }
+}
+
+// FILE: Kotlin.kt
+
+import j.*
+
+class K : <!INAPPLICABLE_CANDIDATE!>Observable<String><!>({})
+
+class J : Observable<String>(null)
diff --git a/compiler/testData/diagnostics/tests/j+k/samWithConsumer.fir.kt b/compiler/testData/diagnostics/tests/j+k/samWithConsumer.fir.kt
new file mode 100644
index 00000000000..6480f97c171
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/samWithConsumer.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+// FULL_JDK
+// FILE: A.java
+import java.util.function.Consumer;
+
+public class A<T> {
+    void test(Consumer<? super T> consumer) {}
+}
+
+// FILE: 1.kt
+import java.util.function.Consumer
+
+fun test(a: A<out Number>) {
+    a.test (Consumer {
+        it checkType { _<Number>() }
+        it.toInt()
+    })
+
+    a.test {
+        it checkType { _<Number>() }
+        it.toInt()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/selectMoreSpecific.fir.kt b/compiler/testData/diagnostics/tests/j+k/selectMoreSpecific.fir.kt
new file mode 100644
index 00000000000..dec7050b358
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/selectMoreSpecific.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public String foo() {}
+    public CharSequence foo() {}
+
+    public static String bar() {}
+    public static CharSequence bar() {}
+}
+
+// FILE: main.kt
+
+fun foo(a: A) {
+    a.<!AMBIGUITY!>foo<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    A.<!AMBIGUITY!>bar<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/serializable.fir.kt b/compiler/testData/diagnostics/tests/j+k/serializable.fir.kt
new file mode 100644
index 00000000000..f326daf6c9d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/serializable.fir.kt
@@ -0,0 +1,60 @@
+// FILE: B.kt
+
+import aa.A.use
+import aa.A.useList
+
+fun testPrimitives(b: Byte, ss: Short, i: Int, l: Long, d: Double, s: String, f: Float, bool: Boolean) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(b)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(ss)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(i)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(l)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(s)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(f)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(d)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(bool)
+}
+
+class N
+class S: java.io.Serializable
+
+fun testArrays(ia: IntArray, ai: Array<Int>, an: Array<N>, a: Array<S>) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(ia)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(ai)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(an)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(a)
+}
+
+fun testLiterals() {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(1)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(1.0)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(11111111111111)
+    <!INAPPLICABLE_CANDIDATE!>use<!>("Asdsd")
+    <!INAPPLICABLE_CANDIDATE!>use<!>(true)
+}
+
+fun testNotSerializable(l: List<Int>) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(l)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(N())
+}
+
+enum class C {
+    E, E2
+}
+
+fun testEnums(a: Enum<*>) {
+    <!INAPPLICABLE_CANDIDATE!>use<!>(C.E)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(C.E2)
+    <!INAPPLICABLE_CANDIDATE!>use<!>(a)
+}
+
+fun testLists(a: List<Int>) {
+    <!INAPPLICABLE_CANDIDATE!>useList<!>(a)
+}
+
+// FILE: aa/A.java
+package aa;
+
+public class A {
+    public static void use(java.io.Serializable s) { }
+    public static void useList(java.util.List<? extends java.io.Serializable> s) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/shadowingPrimitiveStaticField.fir.kt b/compiler/testData/diagnostics/tests/j+k/shadowingPrimitiveStaticField.fir.kt
new file mode 100644
index 00000000000..54cb9615d6f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/shadowingPrimitiveStaticField.fir.kt
@@ -0,0 +1,24 @@
+// FILE: B.kt
+
+import aa.B
+
+fun use() {
+    // checking that CONST is of platform type
+    B.<!AMBIGUITY!>CONST<!> = null
+    B.<!AMBIGUITY!>CONST<!>?.<!UNRESOLVED_REFERENCE!>length<!>
+    B.<!AMBIGUITY!>CONST<!>.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+// FILE: aa/A.java
+package aa;
+
+public class A {
+    public static int CONST = 3;
+}
+
+// FILE: aa/B.java
+package aa;
+
+public class B extends A {
+    public static String CONST = null;
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultEnum.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultEnum.fir.kt
new file mode 100644
index 00000000000..10f4ab7708b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultEnum.fir.kt
@@ -0,0 +1,67 @@
+// FILE: Signs.java
+// ANDROID_ANNOTATIONS
+
+public enum Signs {
+    HELLO,
+    WORLD;
+
+    public static final Signs X;
+    public static final class NOT_ENTRY_EITHER {}
+}
+
+// FILE: Mixed.java
+public enum Mixed {
+    NOT_ENTRY_EITHER;
+
+    public static final class NOT_ENTRY_EITHER {}
+}
+
+// FILE: B.kt
+enum class B {
+    X,
+    Y;
+}
+
+// FILE: A.java
+import kotlin.annotations.jvm.internal.*;
+
+class A {
+    public Signs a(@DefaultValue("HELLO") Signs arg)  {
+        return arg;
+    }
+
+    public B b(@DefaultValue("Y") B arg) {
+        return arg;
+    }
+
+    public void foooo(@DefaultValue("ok") B arg) {
+    }
+
+    public Signs bar(@DefaultValue("X") Signs arg)  {
+        return arg;
+    }
+
+    public Signs baz(@DefaultValue("NOT_ENTRY_EITHER") Signs arg) {
+        return arg;
+    }
+
+    public Mixed bam(@DefaultValue("NOT_ENTRY_EITHER") Mixed arg) {
+        return arg;
+    }
+
+}
+
+// FILE: test.kt
+fun test(){
+    val a = A()
+    a.a()
+    a.a(Signs.HELLO)
+    a.b()
+    a.b(B.X)
+    a.<!INAPPLICABLE_CANDIDATE!>foooo<!>()
+    a.foooo(B.Y)
+    a.bar()
+    a.<!INAPPLICABLE_CANDIDATE!>baz<!>()
+
+    a.bam()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultLongLiteral.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultLongLiteral.fir.kt
new file mode 100644
index 00000000000..78bf0a516ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultLongLiteral.fir.kt
@@ -0,0 +1,49 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+public class A {
+    public void first(@DefaultValue("0x1F") Long value) {
+    }
+
+    public void second(@DefaultValue("0X1F") Long value) {
+    }
+
+    public void third(@DefaultValue("0b1010") Long value) {
+    }
+
+    public void fourth(@DefaultValue("0B1010") Long value) {
+    }
+}
+
+// FILE: B.java
+import kotlin.annotations.jvm.internal.*;
+
+public class B {
+    public void first(@DefaultValue("0x") Long value) {
+    }
+
+    public void second(@DefaultValue("0xZZ") Long value) {
+    }
+
+    public void third(@DefaultValue("0b") Long value) {
+    }
+
+    public void fourth(@DefaultValue("0B1234") Long value) {
+    }
+}
+
+// FILE: test.kt
+fun main(a: A, b: B) {
+    a.first()
+    a.second()
+    a.third()
+    a.fourth()
+
+    b.<!INAPPLICABLE_CANDIDATE!>first<!>()
+    b.<!INAPPLICABLE_CANDIDATE!>second<!>()
+    b.<!INAPPLICABLE_CANDIDATE!>third<!>()
+    b.<!INAPPLICABLE_CANDIDATE!>fourth<!>()
+}
+
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultNull.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultNull.fir.kt
new file mode 100644
index 00000000000..b492eaa5f6f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultNull.fir.kt
@@ -0,0 +1,31 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+public class A {
+    public void foo(@DefaultNull Integer x) {}
+    public void bar(@DefaultNull int x) {}
+}
+
+// FILE: B.java
+import kotlin.annotations.jvm.internal.*;
+
+public class B<T> {
+    public void foo(@DefaultNull T t) { }
+}
+
+// FILE: test.kt
+fun test(a: A, first: B<Int>, second: B<Int?>) {
+    a.foo()
+    a.foo(0)
+
+    a.bar()
+    a.bar(0)
+
+    first.foo()
+    first.foo(5)
+
+    second.foo()
+    second.foo(5)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultNullAndParameter.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultNullAndParameter.fir.kt
new file mode 100644
index 00000000000..444e281e4cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultNullAndParameter.fir.kt
@@ -0,0 +1,57 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+public class A {
+    public void foo(@DefaultNull Integer i) {}
+
+    public void bar(@DefaultNull Integer a) {}
+
+    public void bam(@DefaultNull Integer a) {}
+
+    public void baz(@DefaultValue("42") Integer a) {}
+}
+
+// FILE: AInt.java
+import kotlin.annotations.jvm.internal.*;
+
+public interface AInt {
+    public void foo(@DefaultValue("42") Integer i) {}
+    public void bar(@DefaultNull Integer a) {}
+}
+
+// FILE: B.java
+import kotlin.annotations.jvm.internal.*;
+
+public class B extends A {
+    public void foo(Integer i) {}
+
+    public void bar(@DefaultValue("42") Integer a) {}
+
+    public void bam(@DefaultNull @DefaultValue("42") Integer a) {}
+}
+
+// FILE: C.java
+public class C extends A implements AInt {
+}
+
+// FILE: test.kt
+
+fun test(b: B, c: C) {
+    b.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    b.foo(5)
+    b.bar()
+    b.bar(5)
+    b.bam()
+    b.bam(5)
+
+    c.foo()
+    c.foo(5)
+    c.bar()
+    c.bar(5)
+    c.bam()
+    c.bam(5)
+    c.baz()
+    c.baz(42)
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultParameter.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultParameter.fir.kt
new file mode 100644
index 00000000000..230257989ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/defaultParameter.fir.kt
@@ -0,0 +1,45 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+class A {
+    public void first(@DefaultValue("hello") String value) {
+    }
+
+    public void second(@DefaultValue("first") String a, @DefaultValue("second") String b) {
+    }
+
+    public void third(@DefaultValue("first") String a, String b) {
+    }
+
+    public void fourth(String first, @DefaultValue("second") String second) {
+    }
+
+    public void wrong(@DefaultValue("hello") Integer i) {
+    }
+}
+
+
+// FILE: test.kt
+fun main() {
+    val a = A()
+
+    a.first()
+    a.first("arg")
+
+    a.second()
+    a.second("arg")
+    a.second("first", "second")
+
+    a.<!INAPPLICABLE_CANDIDATE!>third<!>("OK")
+    a.third("first", "second")
+
+    a.<!INAPPLICABLE_CANDIDATE!>fourth<!>()
+    a.fourth("first")
+    a.fourth("first", "second")
+
+    a.<!INAPPLICABLE_CANDIDATE!>wrong<!>()
+    a.wrong(42)
+}
+
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/emptyParameterName.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/emptyParameterName.fir.kt
new file mode 100644
index 00000000000..f9718064622
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/emptyParameterName.fir.kt
@@ -0,0 +1,27 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+class A {
+    public void emptyName(@ParameterName("") String first, @ParameterName("ok") int second) {
+    }
+
+    public void missingName(@ParameterName() String first) {
+    }
+
+    public void numberName(@ParameterName(42) String first) {
+    }
+}
+
+// FILE: test.kt
+fun main() {
+    val test = A()
+    test.emptyName("first", 42)
+    test.<!INAPPLICABLE_CANDIDATE!>emptyName<!>("first", ok = 42)
+
+    test.missingName(`first` = "arg")
+    test.missingName("arg")
+
+    test.numberName("first")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/notNullVarargOverride.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/notNullVarargOverride.fir.kt
new file mode 100644
index 00000000000..338461c1433
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/notNullVarargOverride.fir.kt
@@ -0,0 +1,22 @@
+// FILE: BaseClass.java
+import org.jetbrains.annotations.NotNull;
+
+public class BaseClass {
+    public void loadCache(@NotNull Object... args) {}
+}
+
+// FILE: main.kt
+
+class A : BaseClass() {
+    // org.jetbrains.annotations.NotNull has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any?) {
+        super.loadCache(*args)
+    }
+}
+
+class B : BaseClass() {
+    // org.jetbrains.annotations.NotNull has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any) {
+        super.loadCache(*args)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/nullableVarargOverride.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/nullableVarargOverride.fir.kt
new file mode 100644
index 00000000000..6d130cdebff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/nullableVarargOverride.fir.kt
@@ -0,0 +1,22 @@
+// FILE: BaseClass.java
+import org.jetbrains.annotations.Nullable;
+
+public class BaseClass {
+    public void loadCache(@Nullable Object... args) {}
+}
+
+// FILE: main.kt
+
+class A : BaseClass() {
+    // org.jetbrains.annotations.Nullable has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any?) {
+        super.loadCache(*args)
+    }
+}
+
+class B : BaseClass() {
+    // org.jetbrains.annotations.Nullable has @Target PARAMETER, so it doesn't affect elements type
+    override fun loadCache(vararg args: Any) {
+        super.loadCache(*args)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesDefaultValue.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesDefaultValue.fir.kt
new file mode 100644
index 00000000000..a5f9e3e5c1f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesDefaultValue.fir.kt
@@ -0,0 +1,100 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+class A {
+    public void first(@DefaultValue("42") int arg) {
+    }
+}
+
+// FILE: B.java
+class B {
+    public void first(int arg) {
+    }
+}
+
+// FILE: C.java
+import kotlin.annotations.jvm.internal.*;
+
+class C extends A {
+    public void first(@DefaultValue("73") int arg) {
+    }
+}
+
+// FILE: D.java
+import kotlin.internal.*;
+
+class D extends B {
+    public void first(@DefaultValue("37") int arg) {
+    }
+}
+
+// FILE: E.java
+import kotlin.annotations.jvm.internal.*;
+
+class E extends A {
+    public void first(int arg) {
+    }
+}
+
+// FILE: F.kt
+open class F {
+    open fun foo(x: String = "0") {
+    }
+}
+
+// FILE: G.java
+class G extends F {
+    public void foo(String y) {
+    }
+}
+
+// FILE: K.java
+import kotlin.annotations.jvm.internal.*;
+
+public interface K {
+    public void foo(@DefaultValue("1") String x) { }
+}
+
+// FILE: L.java
+import kotlin.annotations.jvm.internal.*;
+
+public interface L {
+    public void foo(@DefaultValue("1") String x) { }
+}
+
+// FILE: M.java
+public class M implements K, L {
+    public void foo(String x) {
+    }
+}
+
+// FILE: main.kt
+fun main() {
+    val a = A()
+    val c = C()
+    val d = D()
+    val e = E()
+
+    val ac: A = C()
+    val bd: B = D()
+
+    a.first()
+    c.first()
+    ac.first()
+
+    d.<!INAPPLICABLE_CANDIDATE!>first<!>()
+    bd.<!INAPPLICABLE_CANDIDATE!>first<!>()
+
+    e.<!INAPPLICABLE_CANDIDATE!>first<!>()
+
+    val g = G()
+    g.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    g.foo("ok")
+
+    val m = M()
+    m.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+
+}
+
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesParameterName.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesParameterName.fir.kt
new file mode 100644
index 00000000000..3c46406ebaf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/overridesParameterName.fir.kt
@@ -0,0 +1,98 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+class A {
+    public void call(@ParameterName("foo") String arg) {
+    }
+}
+
+// FILE: B.java
+import kotlin.annotations.jvm.internal.*;
+
+class B extends A {
+    public void call(@ParameterName("bar") String arg) {
+    }
+}
+
+// FILE: C.java
+
+class C extends A {
+    public void call(String arg) {
+    }
+}
+
+// FILE: D.kt
+open class D {
+    open fun call(foo: String) {
+    }
+}
+
+// FILE: E.java
+import kotlin.annotations.jvm.internal.*;
+
+class E extends D {
+    public void call(@ParameterName("baz") String bar) {
+    }
+}
+
+// FILE: F.java
+class F extends D {
+    public void call(String baaam) {
+    }
+}
+
+
+// FILE: G.java
+import kotlin.annotations.jvm.internal.*;
+
+class G {
+    public void foo(String bar, @ParameterName("foo") String baz) {
+    }
+}
+
+// FILE: H.java
+class H extends G {
+    public void foo(String baz, String bam) {
+    }
+}
+
+// FILE: test.kt
+fun main() {
+    val a = A()
+    val b = B()
+    val c = C()
+
+    a.<!INAPPLICABLE_CANDIDATE!>call<!>(foo = "hello")
+    a.call(arg = "hello")
+    a.call("hello")
+
+    b.<!INAPPLICABLE_CANDIDATE!>call<!>(foo = "hello")
+    b.call(arg = "hello")
+    b.<!INAPPLICABLE_CANDIDATE!>call<!>(bar = "hello")
+    b.call("hello")
+
+    c.<!INAPPLICABLE_CANDIDATE!>call<!>(foo = "hello")
+    c.call(arg = "hello")
+    c.call("hello")
+
+    val e = E()
+    val f = F()
+
+    e.<!INAPPLICABLE_CANDIDATE!>call<!>(foo = "hello")
+    e.call(bar = "hello")
+    e.<!INAPPLICABLE_CANDIDATE!>call<!>(baz = "hello")
+    e.call("hello")
+
+    f.<!INAPPLICABLE_CANDIDATE!>call<!>(foo = "hello")
+    f.call(baaam = "hello")
+    f.call("hello")
+
+    val g = G()
+    val h = H()
+    g.<!INAPPLICABLE_CANDIDATE!>foo<!>("ok", foo = "hohoho")
+    g.foo("ok", "hohoho")
+    h.<!INAPPLICABLE_CANDIDATE!>foo<!>("ok", foo = "hohoho")
+    h.foo("ok", "hohoho")
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/reorderedParameterNames.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/reorderedParameterNames.fir.kt
new file mode 100644
index 00000000000..3b593be43c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/reorderedParameterNames.fir.kt
@@ -0,0 +1,17 @@
+
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+import kotlin.annotations.jvm.internal.*;
+
+public class A {
+    public void connect(@ParameterName("host") String host, @ParameterName("port") int port) {
+    }
+}
+
+// FILE: test.kt
+fun main() {
+    val test = A()
+    test.connect("127.0.0.1", 8080)
+    test.connect(host = "127.0.0.1", port = 8080)
+    test.connect(port = 8080, host = "127.0.0.1")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/sameParameterName.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/sameParameterName.fir.kt
new file mode 100644
index 00000000000..01a29b0c13c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/sameParameterName.fir.kt
@@ -0,0 +1,17 @@
+
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+import kotlin.annotations.jvm.internal.*;
+
+public class A {
+    public void same(@ParameterName("ok") String first, @ParameterName("ok") String second) {
+    }
+}
+
+// FILE: test.kt
+fun main() {
+    val test = A()
+    test.same("hello", "world")
+    test.<!INAPPLICABLE_CANDIDATE!>same<!>(ok = "hello", ok = <!UNRESOLVED_REFERENCE!>world<!>)
+    test.<!INAPPLICABLE_CANDIDATE!>same<!>("hello", ok = "world")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/specialCharsParameterName.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/specialCharsParameterName.fir.kt
new file mode 100644
index 00000000000..0070bd9f64e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/specialCharsParameterName.fir.kt
@@ -0,0 +1,24 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+import kotlin.annotations.jvm.internal.*;
+import kotlin.internal.*;
+
+public class A {
+    public void dollarName(@ParameterName("$") String host) {
+    }
+
+    public void numberName(@ParameterName("42") String field) {
+    }
+}
+
+// FILE: test.kt
+fun main() {
+    val test = A()
+    test.<!INAPPLICABLE_CANDIDATE!>dollarName<!>(`$` = "hello")
+    test.dollarName("hello")
+    test.dollarName(host = "hello")
+
+    test.<!INAPPLICABLE_CANDIDATE!>numberName<!>(`42` = "world")
+    test.numberName("world")
+    test.numberName(field = "world")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/stableParameterName.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/stableParameterName.fir.kt
new file mode 100644
index 00000000000..44c47d2bfc3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/stableParameterName.fir.kt
@@ -0,0 +1,20 @@
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+import kotlin.annotations.jvm.internal.*;
+
+
+public class A {
+    public void foo(@ParameterName("hello") String world) {}
+}
+
+// FILE: B.kt
+
+class B : A() {
+    override fun foo(hello: String) {}
+}
+
+// FILE: C.kt
+
+class C : A() {
+}
+
diff --git a/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/staticMethodWithDefaultValue.fir.kt b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/staticMethodWithDefaultValue.fir.kt
new file mode 100644
index 00000000000..6f101ae561b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/signatureAnnotations/staticMethodWithDefaultValue.fir.kt
@@ -0,0 +1,17 @@
+// IGNORE_BACKEND: JS, NATIVE
+
+// FILE: A.java
+// ANDROID_ANNOTATIONS
+
+import kotlin.annotations.jvm.internal.*;
+
+class A {
+    public static String withDefault(@DefaultValue("OK") String arg) {
+        return arg;
+    }
+}
+
+// FILE: test.kt
+fun box(): String {
+    return A.withDefault();
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/specialBridges.fir.kt b/compiler/testData/diagnostics/tests/j+k/specialBridges.fir.kt
new file mode 100644
index 00000000000..f83c28a9a99
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/specialBridges.fir.kt
@@ -0,0 +1,7 @@
+// JAVAC_EXPECTED_FILE
+interface I2 {
+    val size: Int
+}
+
+class B2 : java.util.ArrayList<String>(), I2
+
diff --git a/compiler/testData/diagnostics/tests/j+k/specialBuiltIns/hashtableInheritance.fir.kt b/compiler/testData/diagnostics/tests/j+k/specialBuiltIns/hashtableInheritance.fir.kt
new file mode 100644
index 00000000000..3fb99cd2976
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/specialBuiltIns/hashtableInheritance.fir.kt
@@ -0,0 +1,6 @@
+// FULL_JDK
+
+class C1 : java.util.Hashtable<String, Int>()
+class C2 : java.util.Hashtable<String, Int>() {
+    override fun get(key: String) = 123
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/specialBuiltIns/securityProvider.fir.kt b/compiler/testData/diagnostics/tests/j+k/specialBuiltIns/securityProvider.fir.kt
new file mode 100644
index 00000000000..9a532723211
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/specialBuiltIns/securityProvider.fir.kt
@@ -0,0 +1,5 @@
+// FULL_JDK
+
+import java.security.Provider
+
+class Example : Provider("A", 1.0, "B")
diff --git a/compiler/testData/diagnostics/tests/j+k/staticMethodInClass.fir.kt b/compiler/testData/diagnostics/tests/j+k/staticMethodInClass.fir.kt
new file mode 100644
index 00000000000..06c9a89809d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/staticMethodInClass.fir.kt
@@ -0,0 +1,16 @@
+// FILE: JavaClass.java
+
+public class JavaClass {
+    public static String testStatic() {
+        return "OK";
+    }
+
+}
+
+// FILE: 1.kt
+import JavaClass.testStatic
+
+fun test() {
+    JavaClass.testStatic()
+    testStatic()
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/traitDefaultCall.fir.kt b/compiler/testData/diagnostics/tests/j+k/traitDefaultCall.fir.kt
new file mode 100644
index 00000000000..e49d86b7fc5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/traitDefaultCall.fir.kt
@@ -0,0 +1,41 @@
+// FILE: Test.java
+public interface Test {
+    default String test() {
+        return "123";
+    }
+}
+
+// FILE: test.kt
+interface KTrait : Test {
+    fun ktest() {
+        super.test()
+
+        test()
+    }
+}
+
+
+interface KTrait2 : KTrait {
+    fun ktest2() {
+        super.test()
+
+        test()
+    }
+}
+
+class A : KTrait {
+    fun a() {
+        super.test()
+
+        test()
+    }
+}
+
+
+class A2 : KTrait2 {
+    fun a() {
+        super.test()
+
+        test()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/j+k/typeAliasWithSamConstructor.fir.kt b/compiler/testData/diagnostics/tests/j+k/typeAliasWithSamConstructor.fir.kt
new file mode 100644
index 00000000000..808122807cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/typeAliasWithSamConstructor.fir.kt
@@ -0,0 +1,18 @@
+// FILE: OnSubscribe.java
+public interface OnSubscribe<T> {
+    void f();
+}
+
+// FILE: Observable.java
+public class Observable<T> {
+    public Observable(OnSubscribe<T> f) {
+    }
+}
+
+// FILE: Kotlin.kt
+
+typealias ObservableAlias<T> = Observable<T>
+typealias ObservableIntAlias = Observable<Int>
+
+class A : <!INAPPLICABLE_CANDIDATE!>ObservableAlias<String><!>({})
+class B : <!INAPPLICABLE_CANDIDATE!>ObservableIntAlias<!>({})
diff --git a/compiler/testData/diagnostics/tests/j+k/types/arrayList.fir.kt b/compiler/testData/diagnostics/tests/j+k/types/arrayList.fir.kt
new file mode 100644
index 00000000000..68825e9c8d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/types/arrayList.fir.kt
@@ -0,0 +1,15 @@
+// FILE: k.kt
+
+interface ML<T> {
+    public fun foo(): MutableList<T>
+}
+
+class K : J<String>(), ML<String>
+
+// FILE: J.java
+
+import java.util.*;
+
+public class J<T> extends ML<T> {
+    public List<T> foo() { return null; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/types/returnCollection.fir.kt b/compiler/testData/diagnostics/tests/j+k/types/returnCollection.fir.kt
new file mode 100644
index 00000000000..4ead28c1794
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/types/returnCollection.fir.kt
@@ -0,0 +1,13 @@
+// FILE: k.kt
+
+interface K {
+    fun foo(): List<String>
+}
+
+// FILE: J.java
+
+import java.util.*;
+
+interface J extends K {
+    List<String> foo();
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/types/shapeMismatchInCovariantPosition.fir.kt b/compiler/testData/diagnostics/tests/j+k/types/shapeMismatchInCovariantPosition.fir.kt
new file mode 100644
index 00000000000..84c8934b225
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/types/shapeMismatchInCovariantPosition.fir.kt
@@ -0,0 +1,19 @@
+// FILE: k.kt
+
+interface G<T>
+interface SubG : G<String>
+
+interface K {
+    fun foo(): G<String>
+    fun bar(): G<String>?
+}
+
+// FILE: J.java
+
+import java.util.*;
+
+interface J extends K {
+    SubG foo();
+    SubG bar();
+    SubG baz();
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/types/shapeMismatchInCovariantPositionGeneric.fir.kt b/compiler/testData/diagnostics/tests/j+k/types/shapeMismatchInCovariantPositionGeneric.fir.kt
new file mode 100644
index 00000000000..2ab572dca5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/types/shapeMismatchInCovariantPositionGeneric.fir.kt
@@ -0,0 +1,19 @@
+// FILE: k.kt
+
+interface G<T>
+interface SubG<A, B> : G<String>
+
+interface K<KT> {
+    fun foo(): G<KT>
+    fun bar(): G<KT>?
+}
+
+// FILE: J.java
+
+import java.util.*;
+
+interface J extends K<String> {
+    SubG<String, G<String>> foo();
+    SubG<String, G<String>> bar();
+    SubG<String, G<String>> baz();
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/types/typeParameter.fir.kt b/compiler/testData/diagnostics/tests/j+k/types/typeParameter.fir.kt
new file mode 100644
index 00000000000..550b69b506d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/types/typeParameter.fir.kt
@@ -0,0 +1,11 @@
+// FILE: k.kt
+
+interface K {
+    fun <T> foo(t: T)
+}
+
+// FILE: J.java
+
+interface J extends K {
+    <T> void foo(T t);
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/wrongVarianceInJava.fir.kt b/compiler/testData/diagnostics/tests/j+k/wrongVarianceInJava.fir.kt
new file mode 100644
index 00000000000..f9f04ca3148
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/j+k/wrongVarianceInJava.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: A.java
+
+public class A {
+    public static Out<? super CharSequence> foo() { return null; }
+    public static In<? extends CharSequence> bar() { return null; }
+}
+
+// FILE: main.kt
+
+class Out<out E> {
+    fun x(): E = null!!
+}
+
+class In<in F> {
+    fun y(f: F) {}
+}
+
+fun test() {
+    A.foo().x() checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    A.bar().y(null)
+}
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/abstractBaseClassMemberNotImplemented.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/abstractBaseClassMemberNotImplemented.fir.kt
new file mode 100644
index 00000000000..c96d63f07ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/abstractBaseClassMemberNotImplemented.fir.kt
@@ -0,0 +1,9 @@
+abstract class ALeft {
+    abstract fun foo()
+}
+
+interface IRight {
+    fun foo() {}
+}
+
+class CDerived : ALeft(), IRight
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/abstractVsAbstract.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/abstractVsAbstract.fir.kt
new file mode 100644
index 00000000000..e13adb74cea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/abstractVsAbstract.fir.kt
@@ -0,0 +1,13 @@
+interface ILeft {
+    fun foo()
+}
+
+interface IRight {
+    fun foo()
+}
+
+interface IDerived : ILeft, IRight
+
+class CDerived : ILeft, IRight
+
+abstract class ADerived : ILeft, IRight
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/defaultVsAbstract.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/defaultVsAbstract.fir.kt
new file mode 100644
index 00000000000..8dcd1d137ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/defaultVsAbstract.fir.kt
@@ -0,0 +1,13 @@
+interface ILeft {
+    fun foo() {}
+}
+
+interface IRight {
+    fun foo()
+}
+
+interface IDerived : ILeft, IRight
+
+class CDerived : ILeft, IRight
+
+abstract class ADerived : ILeft, IRight
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/hidingMethodOfAny.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/hidingMethodOfAny.fir.kt
new file mode 100644
index 00000000000..ef0f562557e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/hidingMethodOfAny.fir.kt
@@ -0,0 +1,5 @@
+interface IA {
+    fun toString(): String = "IB"
+
+    override fun equals(other: Any?): Boolean
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/implementingMethodOfAny.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/implementingMethodOfAny.fir.kt
new file mode 100644
index 00000000000..5c737fc2420
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/implementingMethodOfAny.fir.kt
@@ -0,0 +1,9 @@
+interface IA {
+    override fun toString(): String = "IA"
+
+    override fun equals(other: Any?): Boolean = super.equals(other)
+
+    override fun hashCode(): Int {
+        return 42;
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/notAMethodOfAny.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/notAMethodOfAny.fir.kt
new file mode 100644
index 00000000000..3c918e0f098
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/notAMethodOfAny.fir.kt
@@ -0,0 +1,3 @@
+interface IC {
+    fun toString(x: String): String = "IC$x"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/overridingMethodOfAnyChain.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/overridingMethodOfAnyChain.fir.kt
new file mode 100644
index 00000000000..b1b1f8944d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/overridingMethodOfAnyChain.fir.kt
@@ -0,0 +1,13 @@
+interface IA
+
+interface IB : IA {
+    override fun toString(): String = "IB"
+}
+
+interface IC : IB {
+    override fun toString(): String = "IC"
+}
+
+interface ID : IC {
+    override fun toString(): String = "ID"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/overridingMethodOfAnyDiamond.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/overridingMethodOfAnyDiamond.fir.kt
new file mode 100644
index 00000000000..73f6b39202b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/overridingMethodOfAnyDiamond.fir.kt
@@ -0,0 +1,11 @@
+interface ILeft {
+    override fun toString(): String
+}
+
+interface IRight {
+    override fun toString(): String
+}
+
+interface IDiamond : ILeft, IRight {
+    override fun toString(): String = "IDiamond"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/java8Overrides/singleRelevantDefault.fir.kt b/compiler/testData/diagnostics/tests/java8Overrides/singleRelevantDefault.fir.kt
new file mode 100644
index 00000000000..9fd93ea94b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/java8Overrides/singleRelevantDefault.fir.kt
@@ -0,0 +1,9 @@
+interface ITop {
+    fun foo() {}
+}
+
+interface ILeft : ITop
+
+interface IRight : ITop
+
+interface IDerived : ILeft, IRight
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/kt13401.fir.kt b/compiler/testData/diagnostics/tests/kt13401.fir.kt
new file mode 100644
index 00000000000..758d2abddff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/kt13401.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+// See KT-13401: SOE in VarianceChecker
+
+interface Rec<T: Rec<T>> {
+    fun t(): T
+}
+interface Super<out U> {
+    fun foo(p: Rec<*>) = p.t()
+}
+// Related variance errors
+class Owner<in T> {
+    inner class Inner<U : T>(val u: U) {
+        fun getT() = u
+    }
+
+    fun foo(arg: Inner<*>) = arg.getT()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/kt310.fir.kt b/compiler/testData/diagnostics/tests/kt310.fir.kt
new file mode 100644
index 00000000000..9e95191526c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/kt310.fir.kt
@@ -0,0 +1,5 @@
+// !WITH_NEW_INFERENCE
+
+fun f(c: LongRange): Int {
+    return c.<!UNRESOLVED_REFERENCE!>start<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/kt435.fir.kt b/compiler/testData/diagnostics/tests/kt435.fir.kt
new file mode 100644
index 00000000000..aec09116fa8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/kt435.fir.kt
@@ -0,0 +1,7 @@
+fun Any.foo1() : (i : Int) -> Unit {
+    return {}
+}
+
+fun test(a : Any) {
+    <!INAPPLICABLE_CANDIDATE!>a.foo1()()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/kt53.fir.kt b/compiler/testData/diagnostics/tests/kt53.fir.kt
new file mode 100644
index 00000000000..be726999125
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/kt53.fir.kt
@@ -0,0 +1,6 @@
+val <T> T.foo : T?
+    get() = null
+
+fun test(): Int? {
+    return 1.foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/automaticLabelFromInfixOperator.fir.kt b/compiler/testData/diagnostics/tests/labels/automaticLabelFromInfixOperator.fir.kt
new file mode 100644
index 00000000000..0e05bbbb547
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/automaticLabelFromInfixOperator.fir.kt
@@ -0,0 +1,17 @@
+fun test(x: List<Int>): Int {
+    x myMap {
+        return@myMap
+    }
+
+    return 0
+}
+
+fun myMap(x: List<Int>): Int {
+    x myMap {
+        return@myMap
+    }
+
+    return 0
+}
+
+infix fun List<Int>.myMap(x: () -> Unit) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/kt1703.fir.kt b/compiler/testData/diagnostics/tests/labels/kt1703.fir.kt
new file mode 100644
index 00000000000..e4a6d4eed25
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt1703.fir.kt
@@ -0,0 +1,15 @@
+//KT-1703 Reference to label is unresolved
+
+fun test() {
+    val ints = Array<Int?>(2, { null })
+    ints.forEach lit@ {
+        if (it == null) return@lit
+        use(it + 5)
+    }
+}
+
+fun <T> Array<out T>.forEach(operation: (T) -> Unit) {
+    for (element in this) operation(element)
+}
+
+fun use(a: Any?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/kt361.fir.kt b/compiler/testData/diagnostics/tests/labels/kt361.fir.kt
new file mode 100644
index 00000000000..18f66608df9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt361.fir.kt
@@ -0,0 +1,11 @@
+fun nonlocals(b : Boolean) {
+    a@{
+        fun foo() {
+            if (b) {
+                return@a 1 // The label must be resolved, but an error should be reported for a non-local return
+            }
+        }
+
+        return@a 5
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/kt3920.fir.kt b/compiler/testData/diagnostics/tests/labels/kt3920.fir.kt
new file mode 100644
index 00000000000..9ae310acc38
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt3920.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+//KT-3920 Labeling information is lost when passing through some expressions
+
+fun test() {
+    run f@{
+        val x = if (1 > 2) return@f 1 else 2
+        2
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/labels/kt3988.fir.kt b/compiler/testData/diagnostics/tests/labels/kt3988.fir.kt
new file mode 100644
index 00000000000..07dbf238721
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt3988.fir.kt
@@ -0,0 +1,21 @@
+//KT-3988 This@label for outer function not resolved
+
+class Comment() {
+    var article = ""
+
+}
+class Comment2() {
+    var article2 = ""
+}
+
+fun new(body: Comment.() -> Unit) = body
+
+fun new2(body: Comment2.() -> Unit) = body
+
+fun main() {
+    new {
+        new2 {
+            this@new //UNRESOLVED REFERENCE
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/kt4247.fir.kt b/compiler/testData/diagnostics/tests/labels/kt4247.fir.kt
new file mode 100644
index 00000000000..25b5f2cb56e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt4247.fir.kt
@@ -0,0 +1,11 @@
+//KT-4247 LABEL_NAME_CLASH
+
+fun foo(bar1: (String.() -> Int) -> Int) {
+    bar1 {
+        this.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    bar1 {
+        this@bar1.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/kt4586.fir.kt b/compiler/testData/diagnostics/tests/labels/kt4586.fir.kt
new file mode 100644
index 00000000000..5ac3e300d34
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt4586.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+//KT-4586 this@ does not work for builders
+
+fun string(init: StringBuilder.() -> Unit): String{
+    val answer = StringBuilder()
+    answer.<!UNRESOLVED_REFERENCE!>init<!>()
+    return answer.toString()
+}
+
+val str = string l@{
+    append("hello, ")
+
+    val sub = string {
+        append("world!")
+        this@l.append(this)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/labels/kt4603.fir.kt b/compiler/testData/diagnostics/tests/labels/kt4603.fir.kt
new file mode 100644
index 00000000000..31e6bb298fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt4603.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+//KT-4603 Labeling information is lost when passing through local classes or objects
+
+fun foo() {
+    val s: Int.() -> Unit = l@{
+        class Local(val y: Int = this@l) {
+            fun bar() {
+                val x: Int = this@l //unresolved
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/labels/kt591.fir.kt b/compiler/testData/diagnostics/tests/labels/kt591.fir.kt
new file mode 100644
index 00000000000..0235783feee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/kt591.fir.kt
@@ -0,0 +1,11 @@
+//KT-591 Unresolved label in valid code
+
+fun test() {
+    val a: (Int?).() -> Unit = a@{
+        if (this != null) {
+            val b: String.() -> Unit = {
+                this@a.<!UNRESOLVED_REFERENCE!>times<!>(5) // a@ Unresolved
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/labelReferencesInsideObjectExpressions.fir.kt b/compiler/testData/diagnostics/tests/labels/labelReferencesInsideObjectExpressions.fir.kt
new file mode 100644
index 00000000000..cc43ae6d1cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/labelReferencesInsideObjectExpressions.fir.kt
@@ -0,0 +1,27 @@
+interface A {
+    fun foo()
+}
+
+interface B {
+    fun bar()
+}
+
+fun B.b() {
+    object : A {
+        override fun foo() {
+            this@b.bar()
+        }
+    }
+}
+
+
+fun test() {
+    fun <T> without(f: T.() -> Unit): Unit = (null!!).<!UNRESOLVED_REFERENCE!>f<!>()
+    without<B>() b@ {
+        object : A {
+            override fun foo() {
+                this@b.bar()
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/labeledFunctionLiteral.fir.kt b/compiler/testData/diagnostics/tests/labels/labeledFunctionLiteral.fir.kt
new file mode 100644
index 00000000000..67361c6adfd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/labeledFunctionLiteral.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+val funLit = lambda@ fun String.() {
+    val d1 = this@lambda
+}
+
+fun test() {
+    val funLit = lambda@ fun String.(): String {
+        return this@lambda
+    }
+}
+
+fun lambda() {
+    val funLit = lambda@ fun String.(): String {
+        return this@lambda
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.fir.kt b/compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.fir.kt
new file mode 100644
index 00000000000..326e7c49271
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/labels/labelsMustBeNamed.fir.kt
@@ -0,0 +1,36 @@
+fun foo(a: Any?): Int {
+    <!SYNTAX!>@<!>{ ->
+        return<!SYNTAX!>@<!>
+    }
+
+    <!SYNTAX!>@<!> while(a == null) {
+        if (true) {
+            break<!SYNTAX!>@<!>
+        }
+        else {
+            continue<!SYNTAX!>@<!>
+        }
+    }
+
+    var b = 1
+
+    (<!SYNTAX!>@<!> b) = 2
+
+    return<!SYNTAX!>@<!> 1
+}
+
+open class A {
+    fun foo() {}
+}
+
+class B : A() {
+    fun bar() {
+        this<!SYNTAX!>@<!>.foo()
+        super<!SYNTAX!>@<!>.foo()
+    }
+}
+
+fun bar(f: () -> Unit) = f
+fun test() {
+    bar <!SYNTAX!>@<!>{}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/lateinit/local/inapplicableLateinitModifier.fir.kt b/compiler/testData/diagnostics/tests/lateinit/local/inapplicableLateinitModifier.fir.kt
new file mode 100644
index 00000000000..c2be8e1ba95
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/lateinit/local/inapplicableLateinitModifier.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VALUE -UNUSED_VARIABLE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+// !LANGUAGE: +LateinitLocalVariables
+
+import kotlin.reflect.KProperty
+
+object Delegate {
+    operator fun getValue(instance: Any?, property: KProperty<*>) : String = ""
+    operator fun setValue(instance: Any?, property: KProperty<*>, value: String) {}
+}
+
+
+fun test() {
+    lateinit val test0: Any
+    lateinit var test1: Int
+    lateinit var test2: Any?
+    lateinit var test3: String = ""
+    lateinit var test4 by Delegate
+}
diff --git a/compiler/testData/diagnostics/tests/lateinit/local/localLateinit.fir.kt b/compiler/testData/diagnostics/tests/lateinit/local/localLateinit.fir.kt
new file mode 100644
index 00000000000..9586a34dfca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/lateinit/local/localLateinit.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: +LateinitLocalVariables
+
+fun test() {
+    lateinit var s: String
+    s = ""
+    s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/lateinit/local/uninitialized.fir.kt b/compiler/testData/diagnostics/tests/lateinit/local/uninitialized.fir.kt
new file mode 100644
index 00000000000..090a7d0cce9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/lateinit/local/uninitialized.fir.kt
@@ -0,0 +1,24 @@
+// !LANGUAGE: +LateinitLocalVariables
+
+fun test1() {
+    lateinit var s: String
+    s.length
+}
+
+fun test2() {
+    lateinit var s: String
+    run {
+        s = ""
+    }
+    s.length
+}
+
+fun almostAlwaysTrue(): Boolean = true
+
+fun test3() {
+    lateinit var s: String
+    if (almostAlwaysTrue()) {
+        s = ""
+    }
+    s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/lateinit/modifierApplicability.fir.kt b/compiler/testData/diagnostics/tests/lateinit/modifierApplicability.fir.kt
new file mode 100644
index 00000000000..fec3fbc5ee7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/lateinit/modifierApplicability.fir.kt
@@ -0,0 +1,71 @@
+// !LANGUAGE: -LateinitTopLevelProperties -LateinitLocalVariables
+import kotlin.reflect.KProperty
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, value: String) {}
+}
+
+public abstract class A<T: Any, V: String?>(lateinit var p2: String) {
+
+    public lateinit val a: String
+    lateinit val b: T
+    private lateinit var c: CharSequence
+
+    lateinit val d: String
+        get
+
+    public lateinit var e: String
+        get
+        private set
+
+    fun a() {
+        lateinit var a: String
+    }
+
+    lateinit var e1: V
+    lateinit var e2: String?
+    lateinit var e3: Int
+    lateinit var e4: Int?
+    lateinit var e5 = "A"
+
+    // With initializer, primitive
+    lateinit var e6 = 3
+
+    lateinit var e7 by CustomDelegate()
+
+    lateinit var e8: String
+        get() = "A"
+
+    lateinit var e9: String
+        set(v) { field = v }
+
+    abstract lateinit var e10: String
+
+    lateinit var String.e11: String
+
+    lateinit var String.e12: String
+}
+
+lateinit val topLevel: String
+lateinit var topLevelMutable: String
+
+public interface Intf {
+    lateinit var str: String
+}
+
+public abstract class AbstractClass {
+    abstract var str: String
+}
+
+public class AbstractClassImpl : AbstractClass() {
+    override lateinit var str: String
+}
+
+public class B {
+    lateinit var a: String
+
+    init {
+        a.length
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/lateinit/modifierApplicability_lv12.fir.kt b/compiler/testData/diagnostics/tests/lateinit/modifierApplicability_lv12.fir.kt
new file mode 100644
index 00000000000..d73c339b13a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/lateinit/modifierApplicability_lv12.fir.kt
@@ -0,0 +1,71 @@
+// !LANGUAGE: +LateinitTopLevelProperties +LateinitLocalVariables
+import kotlin.reflect.KProperty
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, value: String) {}
+}
+
+public abstract class A<T: Any, V: String?>(lateinit var p2: String) {
+
+    public lateinit val a: String
+    lateinit val b: T
+    private lateinit var c: CharSequence
+
+    lateinit val d: String
+        get
+
+    public lateinit var e: String
+        get
+        private set
+
+    fun a() {
+        lateinit var a: String
+    }
+
+    lateinit var e1: V
+    lateinit var e2: String?
+    lateinit var e3: Int
+    lateinit var e4: Int?
+    lateinit var e5 = "A"
+
+    // With initializer, primitive
+    lateinit var e6 = 3
+
+    lateinit var e7 by CustomDelegate()
+
+    lateinit var e8: String
+        get() = "A"
+
+    lateinit var e9: String
+        set(v) { field = v }
+
+    abstract lateinit var e10: String
+
+    lateinit var String.e11: String
+
+    lateinit var String.e12: String
+}
+
+lateinit val topLevel: String
+lateinit var topLevelMutable: String
+
+public interface Intf {
+    lateinit var str: String
+}
+
+public abstract class AbstractClass {
+    abstract var str: String
+}
+
+public class AbstractClassImpl : AbstractClass() {
+    override lateinit var str: String
+}
+
+public class B {
+    lateinit var a: String
+
+    init {
+        a.length
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/lateinit/setter.fir.kt b/compiler/testData/diagnostics/tests/lateinit/setter.fir.kt
new file mode 100644
index 00000000000..18d914f0725
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/lateinit/setter.fir.kt
@@ -0,0 +1,22 @@
+class My {
+
+    lateinit var x: String
+        private set
+
+    lateinit var y: String
+        internal set
+
+    lateinit protected var z: String
+        private set
+
+    lateinit private var w: String
+        // Ok, private var / private set
+        private set
+
+    lateinit protected var v: String
+        public set
+
+    lateinit public var u: String
+        // Ok, public var / public set
+        public set
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/library/Collections.fir.kt b/compiler/testData/diagnostics/tests/library/Collections.fir.kt
new file mode 100644
index 00000000000..23fb5dd6f26
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/library/Collections.fir.kt
@@ -0,0 +1,111 @@
+// !WITH_NEW_INFERENCE
+package collections
+
+fun <T> testCollection(c: Collection<T>, t: T) {
+    c.size
+    c.isEmpty()
+    c.contains(1)
+    val iterator: Iterator<T> = c.iterator()
+    c.containsAll(c)
+
+    val mutableIterator: MutableIterator<T> = c.iterator()
+    c.<!UNRESOLVED_REFERENCE!>add<!>(t)
+    c.<!UNRESOLVED_REFERENCE!>remove<!>(1)
+    c.<!UNRESOLVED_REFERENCE!>addAll<!>(c)
+    c.<!UNRESOLVED_REFERENCE!>removeAll<!>(c)
+    c.<!UNRESOLVED_REFERENCE!>retainAll<!>(c)
+    c.<!UNRESOLVED_REFERENCE!>clear<!>()
+
+}
+fun <T> testMutableCollection(c: MutableCollection<T>, t: T) {
+    c.size
+    c.isEmpty()
+    c.contains(1)
+    val iterator: Iterator<T> = c.iterator()
+    c.containsAll(c)
+
+
+    val mutableIterator: MutableIterator<T> = c.iterator()
+    c.add(t)
+    c.remove(1 as T)
+    c.addAll(c)
+    c.removeAll(c)
+    c.retainAll(c)
+    c.clear()
+}
+
+fun <T> testList(l: List<T>, t: T) {
+    val t: T = l.get(1)
+    val i: Int = l.indexOf(t)
+    val i1: Int = l.lastIndexOf(t)
+    val listIterator: ListIterator<T> = l.listIterator()
+    val listIterator1: ListIterator<T> = l.listIterator(1)
+    val list: List<T> = l.subList(1, 2)
+
+    val value: T = l.<!UNRESOLVED_REFERENCE!>set<!>(1, t)
+    l.<!UNRESOLVED_REFERENCE!>add<!>(1, t)
+    l.<!UNRESOLVED_REFERENCE!>remove<!>(1)
+    val mutableListIterator: MutableListIterator<T> = l.listIterator()
+    val mutableListIterator1: MutableListIterator<T> = l.listIterator(1)
+    val mutableList: MutableList<T> = l.subList(1, 2)
+}
+
+fun <T> testMutableList(l: MutableList<T>, t: T) {
+    val value: T = l.set(1, t)
+    l.add(1, t)
+    l.removeAt(1)
+    val mutableListIterator: MutableListIterator<T> = l.listIterator()
+    val mutableListIterator1: MutableListIterator<T> = l.listIterator(1)
+    val mutableList: MutableList<T> = l.subList(1, 2)
+}
+
+fun <T> testSet(s: Set<T>, t: T) {
+    s.size
+    s.isEmpty()
+    s.contains(1)
+    val iterator: Iterator<T> = s.iterator()
+    s.containsAll(s)
+
+    val mutableIterator: MutableIterator<T> = s.iterator()
+    s.<!UNRESOLVED_REFERENCE!>add<!>(t)
+    s.<!UNRESOLVED_REFERENCE!>remove<!>(1)
+    s.<!UNRESOLVED_REFERENCE!>addAll<!>(s)
+    s.<!UNRESOLVED_REFERENCE!>removeAll<!>(s)
+    s.<!UNRESOLVED_REFERENCE!>retainAll<!>(s)
+    s.<!UNRESOLVED_REFERENCE!>clear<!>()
+
+}
+fun <T> testMutableSet(s: MutableSet<T>, t: T) {
+    s.size
+    s.isEmpty()
+    s.contains(1)
+    val iterator: Iterator<T> = s.iterator()
+    s.containsAll(s)
+
+
+    val mutableIterator: MutableIterator<T> = s.iterator()
+    s.add(t)
+    s.remove(1 as T)
+    s.addAll(s)
+    s.removeAll(s)
+    s.retainAll(s)
+    s.clear()
+}
+
+fun <K, V> testMap(m: Map<K, V>) {
+    val set: Set<K> = m.keys
+    val collection: Collection<V> = m.values
+    val set1: Set<Map.Entry<K, V>> = m.entries
+
+    val mutableSet: MutableSet<K> = m.keys
+    val mutableCollection: MutableCollection<V> = m.values
+    val mutableSet1: MutableSet<MutableMap.MutableEntry<K, V>> = m.entries
+}
+
+fun <K, V> testMutableMap(m: MutableMap<K, V>) {
+    val mutableSet: MutableSet<K> = m.keys
+    val mutableCollection: MutableCollection<V> = m.values
+    val mutableSet1: MutableSet<MutableMap.MutableEntry<K, V>> = m.entries
+}
+
+fun <T> array(vararg t: T): Array<T> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/library/kt828.fir.kt b/compiler/testData/diagnostics/tests/library/kt828.fir.kt
new file mode 100644
index 00000000000..f08475a80eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/library/kt828.fir.kt
@@ -0,0 +1,12 @@
+fun test() {
+    var res : Boolean = true
+    res = (res and false)
+    res = (res or false)
+    res = (res xor false)
+    res = (true and false)
+    res = (true or false)
+    res = (true xor false)
+    res = (!true)
+    res = (true && false)
+    res = (true || false)
+}
diff --git a/compiler/testData/diagnostics/tests/localClasses/localAnnotationClass.fir.kt b/compiler/testData/diagnostics/tests/localClasses/localAnnotationClass.fir.kt
new file mode 100644
index 00000000000..f152deb620b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/localClasses/localAnnotationClass.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: -ProhibitLocalAnnotations
+
+fun f() {
+    annotation class Anno
+
+    @Anno class Local {
+        annotation class Nested
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/localClasses/localAnnotationClassError.fir.kt b/compiler/testData/diagnostics/tests/localClasses/localAnnotationClassError.fir.kt
new file mode 100644
index 00000000000..d8dac02ea1b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/localClasses/localAnnotationClassError.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +ProhibitLocalAnnotations
+
+fun f() {
+    annotation class Anno
+
+    @Anno class Local {
+        annotation class Nested
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/localInterfaces.fir.kt b/compiler/testData/diagnostics/tests/localInterfaces.fir.kt
new file mode 100644
index 00000000000..5e5af2f9926
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/localInterfaces.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun foo() {
+    interface a {}
+    val b = object {
+        interface c {}
+    }
+    class A {
+        interface d {}
+    }
+    val f = {
+        interface e {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/IllegalModifiers.fir.kt b/compiler/testData/diagnostics/tests/modifiers/IllegalModifiers.fir.kt
new file mode 100644
index 00000000000..39c44dd2189
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/IllegalModifiers.fir.kt
@@ -0,0 +1,163 @@
+@<!SYNTAX!><!>myAnnotation public
+package illegal_modifiers
+
+abstract class A() {
+    abstract final fun f()
+    abstract open fun g()
+    final open fun h() {}
+
+    open var r: String
+    get
+    abstract protected set
+}
+
+final interface T {}
+
+class FinalClass() {
+    open fun foo() {}
+    val i: Int = 1
+        open get(): Int = field
+    var j: Int = 1
+        open set(v: Int) {}
+}
+
+private public class C
+private public object D
+
+//A sample annotation to check annotation usage in parameters.
+annotation class annotated(val text: String = "not given")
+
+//Check legal modifiers in constructor
+class LegalModifier(val a: Int, @annotated private var b: String, @annotated vararg v: Int)
+
+//Check illegal modifier in constructor parameters
+class IllegalModifiers1(
+        in
+        out
+        reified
+        enum
+        private
+        const
+        a: Int)
+
+//Check multiple illegal modifiers in constructor
+class IllegalModifiers2(private abstract a: Int)
+
+
+//Check annotations with illegal modifiers in constructor
+class IllegalModifiers3(@annotated public abstract b: String)
+
+//Check annotations and vararg with illegal modifiers in constructor
+class IllegalModifiers4(val a: Int, @annotated("a text") protected vararg v: Int)
+
+//Check illegal modifiers for functions and catch block
+abstract class IllegalModifiers5() {
+
+  //Check illegal modifier in function parameter
+  abstract fun foo(public a: Int, vararg v: String)
+
+  //Check multiple illegal modifiers in function parameter
+  abstract fun bar(public abstract a: Int, vararg v: String)
+
+  //Check annotations with illegal modifiers
+  abstract fun baz(@annotated("a text") public abstract a: Int)
+
+  private fun qux() {
+
+    //Check illegal modifier in catch block
+    try {} catch (in out reified enum public e: Exception) {}
+
+    //Check multiple illegal modifiers in catch block
+    try {} catch (in out reified enum abstract public e: Exception) {}
+
+    //Check annotations with illegal modifiers
+    try {} catch (@annotated("a text") abstract public e: Exception) {}
+  }
+}
+
+//Check illegal modifiers on anonymous initializers
+abstract class IllegalModifiers6() {
+    public init {}
+    private init {}
+    protected init {}
+    vararg init {}
+    abstract init {}
+    open init {}
+    final init {}
+
+    public @annotated init {}
+
+    private @IllegalModifiers6() init {}
+}
+
+// strange inappropriate modifiers usages
+override
+out
+in
+vararg
+reified
+class IllegalModifiers7() {
+    enum
+    inner
+    annotation
+    out
+    in
+    vararg
+    reified
+    val x = 1
+    enum
+    inner
+    annotation
+    out
+    in
+    vararg
+    reified
+    const
+    fun foo() {}
+}
+
+// Secondary constructors
+class IllegalModifiers8 {
+    abstract
+    enum
+    open
+    inner
+    annotation
+    override
+    out
+    in
+    final
+    vararg
+    reified
+    const<!SYNTAX!><!>
+    constructor() {}
+
+    constructor(private enum abstract x: Int) {}
+}
+
+class IllegalModifiers9 {
+    private protected constructor() {}
+    private internal constructor(x: Int) {}
+}
+
+// Illegal modifiers on primary constructor
+
+class IllegalModifiers10
+abstract
+enum
+open
+inner
+annotation
+override
+out
+in
+final
+vararg
+reified
+const constructor()
+
+class IllegalModifiers11 private protected constructor()
+
+class Outer {
+    inner sealed class Inner
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/NoLocalVisibility.fir.kt b/compiler/testData/diagnostics/tests/modifiers/NoLocalVisibility.fir.kt
new file mode 100644
index 00000000000..4f23c38669b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/NoLocalVisibility.fir.kt
@@ -0,0 +1,6 @@
+fun foo() {
+    public class A
+    private class B
+    protected class C
+    internal class D
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/annotations.fir.kt b/compiler/testData/diagnostics/tests/modifiers/annotations.fir.kt
new file mode 100644
index 00000000000..8b30f2bba45
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/annotations.fir.kt
@@ -0,0 +1,12 @@
+annotation class My(
+    public val x: Int,
+    protected val y: Int,
+    internal val z: Int,
+    private val w: Int
+)
+
+open class Your {
+    open val x: Int = 0
+}
+
+annotation class His(override val x: Int): Your()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/applicability.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/applicability.fir.kt
new file mode 100644
index 00000000000..e122b400edd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/applicability.fir.kt
@@ -0,0 +1,110 @@
+// !DIAGNOSTICS:-UNUSED_VARIABLE,-CAST_NEVER_SUCCEEDS,-DIVISION_BY_ZERO
+
+import kotlin.reflect.KProperty
+
+const val topLevel: Int = 0
+const val topLevelInferred = 1
+const var topLeveLVar: Int = 2
+
+private val privateTopLevel = 3
+
+object A {
+    const val inObject: Int = 4
+}
+
+class B(const val constructor: Int = 5)
+
+abstract class C {
+    open const val x: Int = 6
+
+    abstract const val y: Int = 7
+
+    companion object {
+        const val inCompaionObject = 8
+    }
+}
+
+object D : C() {
+    override const val x: Int = 9
+
+    const val inObject = 10
+
+    final const val final = 11
+
+    const val withoutInitializer: Int
+
+    init {
+        withoutInitializer = 12
+    }
+}
+
+const val delegated: Int by Delegate()
+
+
+const val withGetter: Int
+    get() = 13
+
+const val withExplicitDefaultGetter: Int = 1
+    get
+
+fun foo(): Int {
+    const val local: Int = 14
+    return 15
+}
+
+enum class MyEnum {
+    A {
+        const val inEnumEntry = 16
+    };
+    const val inEnum = 17
+}
+
+class Outer {
+    inner class Inner {
+        object C {
+            const val a = 18
+        }
+    }
+}
+
+const val defaultGetter = 19
+    get
+
+const val nonConstInitializer1 = foo()
+const val nonConstInitializer2 = 1 as String
+const val nonConstInitializer3 = 1.0 as String
+const val nonConstInitializer4 = 1 as Double
+const val nonConstInitializer5 = "2" as Int
+const val nonConstInitializer6 = 1/0
+const val nonConstInitializer7 = -1/0
+const val nonConstInitializer8 = 1/0 - 1/0
+const val nonConstInitializer9 = 1.0/0.0 - 1/0
+const val nonConstInitializer10 = 0/0
+const val nonConstInitializer11 = 1 % 0
+const val nonConstInitializer12 = 0 % 0
+const val nonConstInitializer13 = 0.mod(0)
+const val nonConstInitializer14 = 0.rem(0)
+const val nonConstInitializer15 = 0.div(0)
+
+const val constInitializer1 = 1.0/0
+const val constInitializer2 = 1/0.0
+const val constInitializer3 = 1.0/0.0
+const val constInitializer4 = -1.0/0
+const val constInitializer5 = 0.0/0
+const val constInitializer6 = 42 + 1.0/0
+const val constInitializer7 = 42 - 1.0/0
+const val constInitializer8 = 1.0/0 - 1.0/0
+const val constInitializer9 = 0.0/0 + 1.0/0
+const val constInitializer10 = 1.0 % 0
+const val constInitializer11 = 0.0 % 0
+const val constInitializer12 = (-1.0) % 0
+const val constInitializer13 = 1.0.rem(0)
+const val constInitializer14 = 1.0.mod(0)
+const val constInitializer15 = 1.0.div(0)
+
+// ------------------
+class Delegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): Int = 1
+
+    operator fun setValue(thisRef: Any?, prop: KProperty<*>, value: Int) = Unit
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/arrayInAnnotationArgumentType.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/arrayInAnnotationArgumentType.fir.kt
new file mode 100644
index 00000000000..1eb5fb247ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/arrayInAnnotationArgumentType.fir.kt
@@ -0,0 +1,3 @@
+// !WITH_NEW_INFERENCE
+annotation class A(val a: IntArray = arrayOf(1))
+annotation class B(val a: IntArray = intArrayOf(1))
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/constInteraction.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/constInteraction.fir.kt
new file mode 100644
index 00000000000..240bd3d3f71
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/constInteraction.fir.kt
@@ -0,0 +1,18 @@
+const val aConst = 1
+const val bConst = aConst + 1
+
+const val boolVal = bConst > 1 || (B.boolVal && A.boolVal)
+const val stringInterpolation = "Result: ${B.boolVal}"
+
+object A {
+    const val boolVal = bConst + 3 == 5
+
+    const val recursive1: Int = 1 + B.recursive2
+}
+
+class B {
+    companion object {
+        const val boolVal = A.boolVal
+        const val recursive2: Int = A.recursive1 + 2
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/fromJava.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/fromJava.fir.kt
new file mode 100644
index 00000000000..7fad716d109
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/fromJava.fir.kt
@@ -0,0 +1,26 @@
+// FILE: A.java
+
+public class A {
+    public static final int X = 1;
+    public static final int Y;
+
+    public final int z = 3;
+
+    static {
+        Y = 2;
+    }
+}
+
+// FILE: main.kt
+
+annotation class Ann(val x: Int)
+
+@Ann(A.X)
+fun main1() {}
+
+@Ann(A.Y)
+fun main2() {}
+
+val q = A()
+@Ann(q.z)
+fun main3() {}
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/fromJavaSubclass.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/fromJavaSubclass.fir.kt
new file mode 100644
index 00000000000..bace34caa25
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/fromJavaSubclass.fir.kt
@@ -0,0 +1,15 @@
+// FILE: A.java
+
+public class A {
+    public static final String FOO = "foo";
+}
+
+// FILE: B.java
+
+public class B extends A {
+}
+
+// FILE: main.kt
+
+const val K1 = B.FOO
+const val K2 = A.FOO
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/kt12248.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/kt12248.fir.kt
new file mode 100644
index 00000000000..093c6ca967c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/kt12248.fir.kt
@@ -0,0 +1,19 @@
+// FILE: Bar.java
+
+public class Bar {
+    public static final int BAR = Foo.FOO + 1;
+}
+
+// FILE: Test.kt
+
+class Foo {
+    companion object {
+        const val FOO = 1
+    }
+}
+
+class Baz {
+    companion object {
+        const val BAZ = Bar.BAR + 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/kt15913.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/kt15913.fir.kt
new file mode 100644
index 00000000000..13884090354
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/kt15913.fir.kt
@@ -0,0 +1,19 @@
+// FILE: Context.java
+
+public interface Context {
+    String BEAN = "context";
+}
+
+// FILE: Test.kt
+
+annotation class Resource(val name: String)
+
+class MyController {
+    companion object {
+        private const val foo = Context.BEAN
+    }
+
+    @Resource(name = Context.BEAN)
+    fun setContext() {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/noDivisionByZeroFeature.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/noDivisionByZeroFeature.fir.kt
new file mode 100644
index 00000000000..f7f2fb9f75c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/noDivisionByZeroFeature.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: -DivisionByZeroInConstantExpressions
+// !DIAGNOSTICS:-DIVISION_BY_ZERO
+
+const val a = 1 / 0.0
+const val b = 1.0 / 0
+const val c = 0.0 / 0
+const val d = 1.0 % 0
+const val e = 0.0 % 0
+const val f = 0.0.mod(0)
+const val g = 0.0.rem(0)
+const val h = 0.0.div(0)
+
+const val i = 1 / 0
+
+val nonConst1 = 1.0 / 0
+val nonConst2 = 1 / 0
+val nonConst3 = 1.0 % 0
+val nonConst4 = 1 % 0
+val nonConst5 = 1.mod(0)
+val nonConst6 = 1.rem(0)
+val nonConst7 = 1.div(0)
diff --git a/compiler/testData/diagnostics/tests/modifiers/const/types.fir.kt b/compiler/testData/diagnostics/tests/modifiers/const/types.fir.kt
new file mode 100644
index 00000000000..b55bb6d33ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/const/types.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+const val intConst = 1
+const val longConst: Long = 1
+const val boolConst = true
+const val stringConst = "empty"
+
+enum class MyEnum { A }
+
+const val enumConst: MyEnum = MyEnum.A
+const val arrayConst: Array<String> = arrayOf("1")
+const val intArrayConst: IntArray = intArrayOf()
+
+const val unresolvedConst1 = <!UNRESOLVED_REFERENCE!>Unresolved<!>
+const var unresolvedConst2 = <!UNRESOLVED_REFERENCE!>Unresolved<!>
+const val unresolvedConst3 = <!UNRESOLVED_REFERENCE!>Unresolved<!>
+get() = 10
diff --git a/compiler/testData/diagnostics/tests/modifiers/defaultModifier.fir.kt b/compiler/testData/diagnostics/tests/modifiers/defaultModifier.fir.kt
new file mode 100644
index 00000000000..49b79c540d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/defaultModifier.fir.kt
@@ -0,0 +1,55 @@
+companion class A {
+    companion object {
+
+    }
+}
+
+class B {
+    companion object
+
+    val c: Int = 1
+}
+
+class C {
+    companion object A {
+
+    }
+}
+
+class D {
+    companion object A {
+        companion object {
+        }
+    }
+}
+
+companion object G {
+    companion object
+}
+
+companion interface H {
+    companion object
+}
+
+class J {
+    companion object C {
+        companion object
+    }
+}
+
+companion enum class Enum {
+    E1,
+    E2;
+
+    companion object
+}
+
+companion fun main() {
+
+}
+
+companion var prop: Int = 1
+    companion get
+    companion set
+
+class Z(companion val c: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/incompatibleVarianceModifiers.fir.kt b/compiler/testData/diagnostics/tests/modifiers/incompatibleVarianceModifiers.fir.kt
new file mode 100644
index 00000000000..960ca254855
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/incompatibleVarianceModifiers.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+interface Foo<T>
+interface Foo1<in out T>
+interface Foo2<in in T>
+
+fun test1(foo: Foo<in out Int>) = foo
+fun test2(): Foo<in in Int> = throw Exception()
+
+fun test3() {
+    val f: Foo<out out out out Int>
+
+    class Bzz<in in T>
+}
+
+class A {
+    fun <out out T> bar() {
+    }
+}
+
+fun test4(a: A) {
+    a.bar<out out Int>()
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/inlineParameters.fir.kt b/compiler/testData/diagnostics/tests/modifiers/inlineParameters.fir.kt
new file mode 100644
index 00000000000..311f939d9ff
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/inlineParameters.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun foo(noinline x: Int) {}
+
+inline fun bar(y: Int, crossinline x: String) {}
+
+fun gav(noinline x: (Int) -> Unit, crossinline y: (String) -> Int) {}
+
+inline fun correct(noinline x: (Int) -> Unit, crossinline y: (String) -> Int) {}
+
+inline fun incompatible(noinline crossinline x: () -> String) {}
+
+class FunctionSubtype : () -> Unit {
+    override fun invoke() {}
+}
+
+inline fun functionSubtype(
+        noinline f: FunctionSubtype,
+        crossinline g: FunctionSubtype
+) { }
diff --git a/compiler/testData/diagnostics/tests/modifiers/internalInInterface.fir.kt b/compiler/testData/diagnostics/tests/modifiers/internalInInterface.fir.kt
new file mode 100644
index 00000000000..5b1a334f17a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/internalInInterface.fir.kt
@@ -0,0 +1,7 @@
+interface My {
+    internal val x: Int
+    internal val xxx: Int
+        get() = 0
+    internal fun foo(): Int
+    internal fun bar() = 42
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/modifierOnParameterInFunctionType.fir.kt b/compiler/testData/diagnostics/tests/modifiers/modifierOnParameterInFunctionType.fir.kt
new file mode 100644
index 00000000000..ae1ccc95eb6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/modifierOnParameterInFunctionType.fir.kt
@@ -0,0 +1,52 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun f(vararg x: Int) {}
+
+val inVal: (vararg x: Int)->Unit = {}
+
+fun inParam(fn: (vararg x: Int)->Unit) {}
+
+fun inParamNested(fn1: (fn2: (vararg n: Int)->Unit)->Unit) {}
+
+fun inReturn(): (vararg x: Int)->Unit = {}
+
+class A : (vararg Int)->Unit {
+    override fun invoke(p1: Int) {
+        var lambda: (vararg x: Int)->Unit = {}
+    }
+
+    val prop: (vararg x: Int)->Unit
+        get(): (vararg x: Int)->Unit = {}
+}
+
+val allProhibited: (abstract
+                    annotation
+                    companion
+                    const
+                    crossinline
+                    data
+                    enum
+                    external
+                    final
+                    in
+                    inline
+                    inner
+                    internal
+                    lateinit
+                    noinline
+                    open
+                    operator
+                    out
+                    override
+                    private
+                    protected
+                    public
+                    reified
+                    sealed
+                    tailrec
+                    vararg
+
+                    x: Int)->Unit = {}
+
+val valProhibited: (val x: Int)->Unit = {}
+val varProhibited: (var x: Int)->Unit = {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/openInInterface.fir.kt b/compiler/testData/diagnostics/tests/modifiers/openInInterface.fir.kt
new file mode 100644
index 00000000000..8c9497d874f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/openInInterface.fir.kt
@@ -0,0 +1,10 @@
+interface My {
+    open fun foo()
+    open fun bar() {}
+    open abstract fun baz(): Int
+
+    open val x: Int
+    open val y: String
+        get() = ""
+    open abstract val z: Double
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/operatorInfix/LocalFunctions.fir.kt b/compiler/testData/diagnostics/tests/modifiers/operatorInfix/LocalFunctions.fir.kt
new file mode 100644
index 00000000000..69a7f9ebd6e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/operatorInfix/LocalFunctions.fir.kt
@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Example
+
+fun Example.plus(other: Example) = 0
+operator infix fun Example.minus(other: Example) = 0
+
+operator infix fun Example.times(other: Example) = 0
+fun Example.div(other: Example) = 0
+
+fun a() {
+    with (Example()) {
+        operator infix fun Example.plus(other: Example) = ""
+        fun Example.minus(other: Example) = ""
+
+        operator infix fun Example.times(other: Example) = ""
+        fun Example.div(other: Example) = ""
+
+        with (Example()) {
+            val a = Example()
+            val b = Example()
+
+            consumeString(a + b)
+            <!INAPPLICABLE_CANDIDATE!>consumeInt<!>(a - b)
+
+            consumeString(a plus b)
+            <!INAPPLICABLE_CANDIDATE!>consumeInt<!>(a minus b)
+
+            a * b
+            a / b
+
+            a times b
+            a div b
+        }
+    }
+}
+
+fun consumeInt(i: Int) {}
+fun consumeString(s: String) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/operatorInfix/MemberFunctions.fir.kt b/compiler/testData/diagnostics/tests/modifiers/operatorInfix/MemberFunctions.fir.kt
new file mode 100644
index 00000000000..faa594795d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/operatorInfix/MemberFunctions.fir.kt
@@ -0,0 +1,45 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -EXTENSION_SHADOWED_BY_MEMBER
+
+class Example {
+    <!INAPPLICABLE_INFIX_MODIFIER!>operator infix fun plus(other: Example) = 0<!>
+    fun minus(other: Example) = 0
+
+    <!INAPPLICABLE_INFIX_MODIFIER!>operator infix fun times(other: Example) = 0<!>
+    fun div(other: Example) = 0
+}
+
+fun Example.plus(other: Example) = ""
+operator infix fun Example.minus(other: Example) = ""
+
+operator infix fun Example.times(other: Example) = ""
+fun Example.div(other: Example) = ""
+
+fun a() {
+    val a = Example()
+    val b = Example()
+
+    a + b
+    a - b
+    a * b
+    a / b
+
+    a plus b
+    a minus b
+    a times b
+    a div b
+
+    with (Example()) {
+        consumeInt(this + a)
+        <!INAPPLICABLE_CANDIDATE!>consumeString<!>(this - b)
+        consumeInt(this * a)
+        consumeInt(this / b)
+
+        consumeInt(this plus a)
+        <!INAPPLICABLE_CANDIDATE!>consumeString<!>(this minus b)
+        consumeInt(this times a)
+        consumeInt(this div b)
+    }
+}
+
+fun consumeInt(i: Int) {}
+fun consumeString(s: String) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/operatorInfix/Simple.fir.kt b/compiler/testData/diagnostics/tests/modifiers/operatorInfix/Simple.fir.kt
new file mode 100644
index 00000000000..2ecb1895096
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/operatorInfix/Simple.fir.kt
@@ -0,0 +1,45 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -EXTENSION_SHADOWED_BY_MEMBER
+
+open class Example {
+    fun invoke() = 0
+    fun get(i: Int) = 0
+
+    fun component1() = 0
+    fun component2() = 0
+
+    fun inc() = Example()
+
+    fun plus(o: Example) = 0
+}
+
+class Example2 : Example()
+
+operator fun Example.invoke() = ""
+operator fun Example.get(i: Int) = ""
+
+operator fun Example.component1() = ""
+operator fun Example.component2() = ""
+
+operator fun Example.inc() = Example2()
+
+infix fun Example.plus(o: Example) = ""
+
+fun test() {
+    var a = Example()
+    val b = Example()
+
+    <!INAPPLICABLE_CANDIDATE!>consumeString<!>(a())
+    <!INAPPLICABLE_CANDIDATE!>consumeString<!>(a[1])
+
+    val (x, y) = Example()
+    <!INAPPLICABLE_CANDIDATE!>consumeString<!>(x)
+    <!INAPPLICABLE_CANDIDATE!>consumeString<!>(y)
+
+    <!INAPPLICABLE_CANDIDATE!>consumeExample2<!>(++a)
+
+    <!INAPPLICABLE_CANDIDATE!>consumeString<!>(a plus b)
+}
+
+fun consumeInt(i: Int) {}
+fun consumeString(s: String) {}
+fun consumeExample2(e: Example2) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/primaryConstructorMissingBrackets.fir.kt b/compiler/testData/diagnostics/tests/modifiers/primaryConstructorMissingBrackets.fir.kt
new file mode 100644
index 00000000000..f6b4a247fd1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/primaryConstructorMissingBrackets.fir.kt
@@ -0,0 +1,2 @@
+class A private constructor<!SYNTAX!><!> {
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/primaryConstructorMissingKeyword.fir.kt b/compiler/testData/diagnostics/tests/modifiers/primaryConstructorMissingKeyword.fir.kt
new file mode 100644
index 00000000000..babb16e5b07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/primaryConstructorMissingKeyword.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+annotation class Ann(val x: Int = 1)
+class A private (val x: Int) {
+inner class B @Ann(2) (val y: Int)
+
+fun foo() {
+    class C private @Ann(3) (args: Int)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/privateInInterface.fir.kt b/compiler/testData/diagnostics/tests/modifiers/privateInInterface.fir.kt
new file mode 100644
index 00000000000..75878595978
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/privateInInterface.fir.kt
@@ -0,0 +1,12 @@
+interface My {
+    private val x: Int
+    private abstract val xx: Int
+    private val xxx: Int
+        get() = 0
+    final val y: Int
+    final val yy: Int
+        get() = 1
+    private fun foo(): Int
+    // ok
+    private fun bar() = 42
+}
diff --git a/compiler/testData/diagnostics/tests/modifiers/protected.fir.kt b/compiler/testData/diagnostics/tests/modifiers/protected.fir.kt
new file mode 100644
index 00000000000..203b968c732
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/protected.fir.kt
@@ -0,0 +1,21 @@
+class My(protected val x: Int) {
+    class Her(protected val x: Int)
+
+    inner class Its(protected val x: Int)
+}
+
+object Your {
+    protected fun foo() = 3
+}
+
+annotation class His(protected val x: Int)
+
+enum class Our(protected val x: Int) {
+    FIRST(42) {
+        protected fun foo() = 13
+    }
+}
+
+interface Their {
+    protected fun foo() = 7
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/redundantTargets.fir.kt b/compiler/testData/diagnostics/tests/modifiers/redundantTargets.fir.kt
new file mode 100644
index 00000000000..c2cc1149db6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/redundantTargets.fir.kt
@@ -0,0 +1,10 @@
+open interface First
+// Now inspection
+abstract interface Second
+// Now inspection
+final enum class Third {
+    FOURTH, 
+    FIFTH
+}
+// Now inspection
+final object Sixth
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/modifiers/repeatedModifiers.fir.kt b/compiler/testData/diagnostics/tests/modifiers/repeatedModifiers.fir.kt
new file mode 100644
index 00000000000..0ae92441676
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/modifiers/repeatedModifiers.fir.kt
@@ -0,0 +1,41 @@
+abstract abstract class Foo
+public public class Bar
+open open final class Baz {
+    private private fun foo() {}
+}
+
+class Bzz(public public val q: Int = 1) {
+    public public val x: Int = 2
+
+    public val y: Int
+        public public get() = 3
+
+    val z: Int
+        open final get() = 4
+
+    public public class B(public public val z: Int = 1) {
+        public public val y: Int = 2
+
+        public val x: Int
+            public public get() = 3
+    }
+
+    public public object C {
+        public public val y: Int = 1
+        public public fun z(): Int = 1
+    }
+}
+
+public public val bar: Int = 1
+
+public public fun foo(): Int = 1
+
+fun test() {
+    public public class B(public public val z: Int = 1) {
+        public public val y: Int = 2
+
+        public val x: Int
+            public public get() = 3
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/collectionMethodStub.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/collectionMethodStub.fir.kt
new file mode 100644
index 00000000000..fb8a15bf719
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/collectionMethodStub.fir.kt
@@ -0,0 +1,21 @@
+// FILE: f1.kt
+// SKIP_TXT
+
+package kotlin
+
+class Unit
+
+// FILE: f2.kt
+
+class C: MutableIterator<Int> {
+    override fun remove(): Unit {
+        throw UnsupportedOperationException()
+    }
+    override fun next(): Int {
+        throw UnsupportedOperationException()
+    }
+    override fun hasNext(): Boolean {
+        throw UnsupportedOperationException()
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/differentGenericArguments.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/differentGenericArguments.fir.kt
new file mode 100644
index 00000000000..17bd97d27f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/differentGenericArguments.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A
+public class M1 {
+    public val a: A = A()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public class A<T>
+
+public fun foo(a: A<Int>) {
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    foo(M1().a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/differentGenericArgumentsReversed.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/differentGenericArgumentsReversed.fir.kt
new file mode 100644
index 00000000000..2b2f8bdf6a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/differentGenericArgumentsReversed.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A<T>
+public class M1 {
+    public val a: A<Int> = A<Int>()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public class A
+
+public fun foo(a: A) {
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(M1().a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateClass.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateClass.fir.kt
new file mode 100644
index 00000000000..28bed038c27
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateClass.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A
+public class B {
+    public val a: A = A()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public class A {
+    val x = 1
+}
+
+public fun foo(a: A) {
+    a.x + 1
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    foo(B().a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateNestedClasses.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateNestedClasses.fir.kt
new file mode 100644
index 00000000000..6fc7ff0296c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateNestedClasses.fir.kt
@@ -0,0 +1,68 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A {
+    public class B
+    public object C
+    companion object {
+        public class D {
+            public object E
+        }
+        public class G
+    }
+
+    public inner class F
+}
+
+public class M1 {
+    public val a: A = A()
+    public val b: A.B = A.B()
+    public val c: A.C = A.C
+    public val d: A.Companion.D = A.Companion.D()
+    public val e: A.Companion.D.E = A.Companion.D.E
+    public val f: A.F = A().F()
+    public val g: A.Companion.G = A.Companion.G()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public class A {
+    public class B
+    public class C
+    companion object {
+        public class D {
+            public class E
+        }
+    }
+    public class G
+    public inner class F
+}
+
+public fun a(p: A) {}
+public fun b(p: A.B) {}
+public fun c(p: A.C) {}
+public fun d(p: A.Companion.D) {}
+public fun e(p: A.Companion.D.E) {}
+public fun f(p: A.F) {}
+public fun g(p: A.G) {}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test(m1: M1) {
+    a(m1.a)
+    b(m1.b)
+    c(m1.c)
+    d(m1.d)
+    e(m1.e)
+    f(m1.f)
+    <!INAPPLICABLE_CANDIDATE!>g<!>(m1.g)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateSuperClass.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateSuperClass.fir.kt
new file mode 100644
index 00000000000..73f4f212412
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateSuperClass.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public interface A
+public class B : A
+public class M1 {
+    public val b: B = B()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public interface A
+
+public fun foo(a: A) {
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    foo(M1().b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/genericArgumentNumberMismatch.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/genericArgumentNumberMismatch.fir.kt
new file mode 100644
index 00000000000..31e558b93c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/genericArgumentNumberMismatch.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A<X, Y>
+public class M1 {
+    public val a: A<Int> = A<Int, Int>()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public class A<X, Y>
+
+public fun foo(a: A<Int>) {
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    foo(M1().a)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1) // error type on the declaration site
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/genericSuperClass.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/genericSuperClass.fir.kt
new file mode 100644
index 00000000000..a90aa734312
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/genericSuperClass.fir.kt
@@ -0,0 +1,42 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public interface A<T>
+public interface C
+public interface D<T>
+public class B : A<Int>, C, D<Int>
+public class M1 {
+    public val b: B = B()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public interface A
+public interface C<T>
+public interface D<T>
+
+public fun a(a: A) {
+}
+
+public fun c(c: C<Int>) {
+}
+
+public fun d(d: D<Int>) {
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>a<!>(M1().b) // Type arguments do not match
+    c(M1().b) // Type arguments do not match
+    d(M1().b) // Type arguments do match
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/inTheSameModuleWithUsage.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/inTheSameModuleWithUsage.fir.kt
new file mode 100644
index 00000000000..20f29622e77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/inTheSameModuleWithUsage.fir.kt
@@ -0,0 +1,23 @@
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A
+public class B {
+    public val a: A = A()
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+package p
+
+class A {
+    fun foo() {}
+}
+
+fun test() {
+    val a: A = B().a
+    a.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/inTheSameModuleWithUsageNoTypeAnnotation.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/inTheSameModuleWithUsageNoTypeAnnotation.fir.kt
new file mode 100644
index 00000000000..6dbc4b1496d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/inTheSameModuleWithUsageNoTypeAnnotation.fir.kt
@@ -0,0 +1,23 @@
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A
+public class B {
+    public val a: A = A()
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+package p
+
+class A {
+    fun foo() {}
+}
+
+fun test() {
+    val a = B().a
+    a.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/members.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/members.fir.kt
new file mode 100644
index 00000000000..eb795c7bbe0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/members.fir.kt
@@ -0,0 +1,38 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A {
+    public fun m1() {}
+}
+public class M1 {
+    public val a: A = A()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public class A {
+    public fun m2() {}
+}
+
+public class M2 {
+    public val a: A = A()
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test(a: A) {
+    a.m1()
+
+    M1().a.m1()
+
+    M2().a.<!UNRESOLVED_REFERENCE!>m2<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/sameClassNameDifferentPackages.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/sameClassNameDifferentPackages.fir.kt
new file mode 100644
index 00000000000..6de2c5bc250
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/sameClassNameDifferentPackages.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A
+public class B {
+    public val a: A = A()
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+import p.*
+
+class A
+
+fun test() {
+    val a: A = B().a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateClass/sameGenericArguments.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/sameGenericArguments.fir.kt
new file mode 100644
index 00000000000..bc4cf46afd4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateClass/sameGenericArguments.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A<T>
+public class M1 {
+    public val a: A<Int> = A()
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public class A<T>
+
+public fun foo(a: A<Int>) {
+}
+
+// MODULE: m3(m1, m2)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    foo(M1().a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParams.fir.kt
new file mode 100644
index 00000000000..5b0df4dc633
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParams.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B<T> {
+    public fun foo(a: T)
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C<X> : B<X> {
+    override fun foo(a: X)
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B<T> {
+    public fun foo(a: T)
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B<String>?) {
+    if (b is C) {
+        b?.foo("")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsBoundMismatch.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsBoundMismatch.fir.kt
new file mode 100644
index 00000000000..4aadd61475a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsBoundMismatch.fir.kt
@@ -0,0 +1,38 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B<T> {
+    public fun foo(a: T?)
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C<X> : B<X> {
+    override fun foo(a: X?)
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface Tr
+
+public interface B<T: Tr?> {
+    public fun foo(a: T?)
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B<Tr>?) {
+    if (b is C) {
+        b?.<!AMBIGUITY!>foo<!>(null)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsIndexMismatch.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsIndexMismatch.fir.kt
new file mode 100644
index 00000000000..00da81c4009
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsIndexMismatch.fir.kt
@@ -0,0 +1,34 @@
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B<T, Z> {
+    public fun foo(a: T?)
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C<X, Z> : B<X, Z> {
+    override fun foo(a: X?)
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B<Z, T> {
+    public fun foo(a: T?)
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun <Y, Z> test(b: B<Y, Z>?) {
+    if (b is C<Y, Z>) {
+        b?.foo(null)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsNameMismatch.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsNameMismatch.fir.kt
new file mode 100644
index 00000000000..3a6fd9ff269
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsNameMismatch.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B<T> {
+    public fun foo(a: T)
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C<X> : B<X> {
+    override fun foo(a: X)
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B<T1> {
+    public fun foo(a: T1)
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun <Y> test(b: B<Y>?, y: Y) {
+    if (b is C) {
+        b?.foo(y)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInReturnType.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInReturnType.fir.kt
new file mode 100644
index 00000000000..de9a558ecd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInReturnType.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B<T> {
+    public fun foo(): T
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C<X> : B<X> {
+    override fun foo(): X
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B<T> {
+    public fun foo(): T
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B<String>?) {
+    if (b is C) {
+        b?.<!AMBIGUITY!>foo<!>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classVsFunctionGenericsInParamsMismatch.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classVsFunctionGenericsInParamsMismatch.fir.kt
new file mode 100644
index 00000000000..0afb87446e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classVsFunctionGenericsInParamsMismatch.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B<T> {
+    public fun <R> foo(a: T, b : R)
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B<Any?> {
+    override fun <R> foo(a: Any?, b : R)
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun <T, R> foo(a: T, b: R)
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?, c: C) {
+    b?.foo(1, 1)
+    c.foo(1, 1)
+    if (b is C) {
+        b?.foo(1, 1)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/covariantReturnTypes.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/covariantReturnTypes.fir.kt
new file mode 100644
index 00000000000..c3df30c4c78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/covariantReturnTypes.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun getParent(): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun getParent(): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun getParent(): Any?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.getParent()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differenceInParamNames.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differenceInParamNames.fir.kt
new file mode 100644
index 00000000000..5f278c9cf55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differenceInParamNames.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun foo(a: Int, b: String): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun foo(a: Int, b: String): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun foo(a1: Int, b1: String): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.foo(1, "")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentGenericsInParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentGenericsInParams.fir.kt
new file mode 100644
index 00000000000..8dbd7151a07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentGenericsInParams.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m0
+// FILE: a.kt
+package p
+
+public interface G1<T>
+public interface G2<A, B>
+
+// MODULE: m1(m0)
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun foo(a: G1<Int>?, b: G2<B, String>?)
+}
+
+// MODULE: m2(m1, m0)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun foo(a: G1<Int>?, b: G2<B, String>?)
+
+}
+
+// MODULE: m3(m0)
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun foo(a: G1<out Any?>?, b: G2<Int, out Any?>?)
+}
+
+// MODULE: m4(m3, m2, m0)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.foo(null, null)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentNumberOfParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentNumberOfParams.fir.kt
new file mode 100644
index 00000000000..59575852fbf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentNumberOfParams.fir.kt
@@ -0,0 +1,34 @@
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun foo(a: Int, b: String): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun foo(a: Int, b: String): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun foo(a: Int, b: String, c: Int = 0): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.foo(1, "")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentReturnTypes.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentReturnTypes.fir.kt
new file mode 100644
index 00000000000..d332b7a100f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/differentReturnTypes.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun getParent(): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun getParent(): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun getParent(): Int
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.getParent()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/extensionMatch.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/extensionMatch.fir.kt
new file mode 100644
index 00000000000..60d54f8cf72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/extensionMatch.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun String.getParent(): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public class C : B {
+    override fun String.getParent(): B? = null
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun String.getParent(): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun B.test() {
+    if (this is C) {
+        "".getParent()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParams.fir.kt
new file mode 100644
index 00000000000..ff4d22e7a93
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParams.fir.kt
@@ -0,0 +1,42 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun <T> foo(a: T): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.foo<String>("")
+    }
+}
+
+fun test1(b: B?) {
+    if (b is C) {
+        b?.foo("")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsBoundsMismatch.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsBoundsMismatch.fir.kt
new file mode 100644
index 00000000000..f9946ea73d7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsBoundsMismatch.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun <T> foo(a: T): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface Tr
+
+public interface B {
+    public fun <T: Tr?> foo(a: T): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        // hard to find parameters for an ambiguous call, so we rely on NONE_APPLICABLE here
+        // as opposed to diagnostics for a single unmatched candidate
+        b?.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsEqNull.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsEqNull.fir.kt
new file mode 100644
index 00000000000..664571d7d31
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsEqNull.fir.kt
@@ -0,0 +1,52 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun <T> foo(a: T): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b == null) return
+    b?.foo<String>("")
+}
+
+fun test1(b: B?) {
+    if (b != null) {
+        b?.foo<String>("")
+    }
+}
+
+fun test2(b: B?) {
+    if (b == null) return
+    b?.foo("")
+}
+
+fun test3(b: B?) {
+    if (b != null) {
+        b?.foo("")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsNotIs.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsNotIs.fir.kt
new file mode 100644
index 00000000000..e24aee75faf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsNotIs.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun <T> foo(a: T): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b !is C)  return
+    b?.foo("")
+}
+
+fun test1(b: B?) {
+    if (b !is C)  return
+    b?.foo<String>("")
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsReturnFooT.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsReturnFooT.fir.kt
new file mode 100644
index 00000000000..5e775bc5e72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsReturnFooT.fir.kt
@@ -0,0 +1,44 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface Foo<T>
+
+public interface B {
+    public fun <T> foo(a: T): Foo<T>
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun <T> foo(a: T): Foo<T>
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface Foo<T>
+
+public interface B {
+    public fun <T> foo(a: T): Foo<T>
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b !is C)  return
+    b?.foo("")
+}
+
+fun test1(b: B?) {
+    if (b !is C)  return
+    b?.foo<String>("")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsReturnT.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsReturnT.fir.kt
new file mode 100644
index 00000000000..494c865981b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/functionGenericsInParamsReturnT.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): T
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun <T> foo(a: T): T
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun <T> foo(a: T): T
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b !is C)  return
+    b?.foo("")
+}
+
+fun test1(b: B?) {
+    if (b !is C)  return
+    b?.foo<String>("")
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/incompleteCodeNoNoneApplicable.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/incompleteCodeNoNoneApplicable.fir.kt
new file mode 100644
index 00000000000..3bd3957db38
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/incompleteCodeNoNoneApplicable.fir.kt
@@ -0,0 +1,20 @@
+// MODULE: m1
+// FILE: a.kt
+package p
+
+fun f(s: String, t: String) = s + t
+
+// MODULE: m2
+// FILE: b.kt
+package p
+
+fun f(s: String, t: String) = t + s
+
+// MODULE: m3(m1, m2)
+// FILE: c.kt
+import p.f
+
+fun test() {
+    // There should be no "none applicable" error here
+    <!INAPPLICABLE_CANDIDATE!>f<!>(
+<!SYNTAX!><!>}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/noGenericsInParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/noGenericsInParams.fir.kt
new file mode 100644
index 00000000000..5a5eb3c618f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/noGenericsInParams.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun foo(a: Int, b: String): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun foo(a: Int, b: String): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun foo(a: Int, b: String): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.foo(1, "")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/noParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/noParams.fir.kt
new file mode 100644
index 00000000000..67a86edc2e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/noParams.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun getParent(): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public class C : B {
+    override fun getParent(): B? = null
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun getParent(): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.getParent()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/sameGenericsInParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/sameGenericsInParams.fir.kt
new file mode 100644
index 00000000000..2e8bfca20f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/sameGenericsInParams.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
+
+// MODULE: m0
+// FILE: a.kt
+package p
+
+public interface G1<T>
+public interface G2<A, B>
+
+// MODULE: m1(m0)
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun foo(a: G1<Int>, b: G2<B, String>): B?
+}
+
+// MODULE: m2(m1, m0)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun foo(a: G1<Int>, b: G2<B, String>): B?
+
+}
+
+// MODULE: m3(m0)
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun foo(a: G1<Int>, b: G2<B, String>): B?
+}
+
+// MODULE: m4(m3, m2, m0)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?, a: G1<Int>, b1: G2<B, String>) {
+    if (b is C) {
+        b?.foo(a, b1)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/simpleWithInheritance.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/simpleWithInheritance.fir.kt
new file mode 100644
index 00000000000..4076dbb3560
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/simpleWithInheritance.fir.kt
@@ -0,0 +1,38 @@
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B {
+    public fun getParent(): B?
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B {
+    override fun getParent(): B?
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun getParent(): B?
+}
+
+public interface D : B {
+    override fun getParent(): B?
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C && b is D) {
+        b?.<!AMBIGUITY!>getParent<!>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/sinceKotlin.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/sinceKotlin.fir.kt
new file mode 100644
index 00000000000..f3aa06a1cf2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/sinceKotlin.fir.kt
@@ -0,0 +1,34 @@
+// !API_VERSION: 1.0
+// MODULE: m1
+// FILE: a.kt
+
+package p1
+
+@SinceKotlin("1.1")
+fun foo(s: Int): String = s.toString()
+
+// MODULE: m2
+// FILE: b.kt
+
+package p2
+
+fun foo(s: Int): Int = s
+
+// MODULE: m3(m1, m2)
+// FILE: severalStarImports.kt
+import p1.*
+import p2.*
+
+fun test1(): Int {
+    val r = <!AMBIGUITY!>foo<!>(42)
+    return r
+}
+
+// FILE: explicitlyImportP1.kt
+import p1.foo  // TODO: consider reporting API_NOT_AVAILABLE here
+import p2.*
+
+fun test2(): Int {
+    val r = foo(42)
+    return r
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/substitutedGenericInParams.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/substitutedGenericInParams.fir.kt
new file mode 100644
index 00000000000..e46d3003573
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/substitutedGenericInParams.fir.kt
@@ -0,0 +1,34 @@
+// MODULE: m1
+// FILE: a.kt
+package p
+
+public interface B<T> {
+    public fun foo(a: T)
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package p
+
+public interface C : B<String> {
+    override fun foo(a: String)
+
+}
+
+// MODULE: m3
+// FILE: b.kt
+package p
+
+public interface B {
+    public fun foo(a: String)
+}
+
+// MODULE: m4(m3, m2)
+// FILE: c.kt
+import p.*
+
+fun test(b: B?) {
+    if (b is C) {
+        b?.foo("")
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/differentSuperTraits.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/differentSuperTraits.fir.kt
new file mode 100644
index 00000000000..99450485c7a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/differentSuperTraits.fir.kt
@@ -0,0 +1,31 @@
+// MODULE: m1
+// FILE: x.kt
+package p
+
+public interface Base {
+    public fun foo() {}
+}
+
+public interface A : Base {
+    override fun foo() {}
+}
+
+public interface C : A
+
+
+// MODULE: m2
+// FILE: x.kt
+package p
+
+public interface Base {
+    public fun foo() {}
+}
+
+public interface B : Base
+
+// MODULE: m3(m1, m2)
+// FILE: x.kt
+
+import p.*
+
+class Foo: C, B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTrait.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTrait.fir.kt
new file mode 100644
index 00000000000..b6d5d833f04
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTrait.fir.kt
@@ -0,0 +1,26 @@
+// MODULE: m1
+// FILE: x.kt
+package p
+
+public interface Base {
+    public fun foo() {}
+}
+
+public interface A : Base
+
+// MODULE: m2
+// FILE: x.kt
+package p
+
+public interface Base {
+    public fun foo() {}
+}
+
+public interface B : Base
+
+// MODULE: m3(m1, m2)
+// FILE: x.kt
+
+import p.*
+
+class Foo: A, B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTraitDifferentBounds.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTraitDifferentBounds.fir.kt
new file mode 100644
index 00000000000..4c1e52747a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTraitDifferentBounds.fir.kt
@@ -0,0 +1,29 @@
+// MODULE: m1
+// FILE: x.kt
+package p
+
+public interface Base {
+    public fun <T> foo(t: Array<T>) {}
+}
+
+public interface A : Base
+
+// MODULE: m2
+// FILE: x.kt
+package p
+
+public interface Base {
+    public fun <T: Base> foo(t: Array<T>) {}
+}
+
+public interface B : Base
+
+// MODULE: m3(m1, m2)
+// FILE: x.kt
+
+import p.*
+
+class Foo: A, B {
+    override fun <T> foo(t: Array<T>) {}
+    override fun <T: Base> foo(t: Array<T>) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTraitGenerics.fir.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTraitGenerics.fir.kt
new file mode 100644
index 00000000000..6fceaf1f9e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateSuper/sameSuperTraitGenerics.fir.kt
@@ -0,0 +1,26 @@
+// MODULE: m1
+// FILE: x.kt
+package p
+
+public interface Base<T> {
+    public fun foo(t: T) {}
+}
+
+public interface A<T> : Base<T>
+
+// MODULE: m2
+// FILE: x.kt
+package p
+
+public interface Base<T> {
+    public fun foo(t: T) {}
+}
+
+public interface B : Base<String>
+
+// MODULE: m3(m1, m2)
+// FILE: x.kt
+
+import p.*
+
+class Foo: A<String>, B
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/hiddenClass/deprecatedHiddenImportPriority.fir.kt b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/deprecatedHiddenImportPriority.fir.kt
new file mode 100644
index 00000000000..b7dca29721c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/deprecatedHiddenImportPriority.fir.kt
@@ -0,0 +1,37 @@
+// MODULE: m1
+// FILE: a.kt
+
+package p1
+
+@Deprecated("Use p2.A instead", level = DeprecationLevel.HIDDEN)
+class A {
+    fun m1() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p2
+
+class A {
+    fun m2() {}
+}
+
+// MODULE: m3(m1, m2)
+// FILE: severalStarImports.kt
+import p1.*
+import p2.*
+
+fun test(a: A) {
+    a.m1()
+    a.<!UNRESOLVED_REFERENCE!>m2<!>()
+}
+
+// FILE: explicitlyImportP1.kt
+import p1.A
+import p2.*
+
+fun test(a: A) {
+    a.m1()
+    a.<!UNRESOLVED_REFERENCE!>m2<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/hiddenClass/deprecatedHiddenMultipleClasses.fir.kt b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/deprecatedHiddenMultipleClasses.fir.kt
new file mode 100644
index 00000000000..2290396a108
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/deprecatedHiddenMultipleClasses.fir.kt
@@ -0,0 +1,46 @@
+// MODULE: m1
+// FILE: a.kt
+
+package p1
+
+@Deprecated("1", level = DeprecationLevel.HIDDEN)
+class A(val v1: Unit)
+
+// MODULE: m2
+// FILE: b.kt
+
+package p2
+
+@Deprecated("2", level = DeprecationLevel.HIDDEN)
+class A(val v2: Unit)
+
+// MODULE: m3
+// FILE: c.kt
+
+package p3
+
+@Deprecated("3", level = DeprecationLevel.HIDDEN)
+class A(val v3: Unit)
+
+// MODULE: m4(m1, m2, m3)
+// FILE: oneExplicitImportOtherStars.kt
+import p1.*
+import p2.A
+import p3.*
+
+fun test(a: A) {
+    a.<!UNRESOLVED_REFERENCE!>v1<!>
+    a.v2
+    a.<!UNRESOLVED_REFERENCE!>v3<!>
+}
+
+// FILE: severalStarImports.kt
+import p1.*
+import p2.*
+import p3.*
+
+fun test(a: A) {
+    a.v1
+    a.<!UNRESOLVED_REFERENCE!>v2<!>
+    a.<!UNRESOLVED_REFERENCE!>v3<!>
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/hiddenClass/sinceKotlinImportPriority.fir.kt b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/sinceKotlinImportPriority.fir.kt
new file mode 100644
index 00000000000..0af9e1e0168
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/sinceKotlinImportPriority.fir.kt
@@ -0,0 +1,38 @@
+// !API_VERSION: 1.0
+// MODULE: m1
+// FILE: a.kt
+
+package p1
+
+@SinceKotlin("1.1")
+class A {
+    fun m1() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p2
+
+class A {
+    fun m2() {}
+}
+
+// MODULE: m3(m1, m2)
+// FILE: severalStarImports.kt
+import p1.*
+import p2.*
+
+fun test(a: A) {
+    a.m1()
+    a.<!UNRESOLVED_REFERENCE!>m2<!>()
+}
+
+// FILE: explicitlyImportP1.kt
+import p1.A
+import p2.*
+
+fun test(a: A) {
+    a.m1()
+    a.<!UNRESOLVED_REFERENCE!>m2<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/hiddenClass/sinceKotlinMultipleClasses.fir.kt b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/sinceKotlinMultipleClasses.fir.kt
new file mode 100644
index 00000000000..5979ec665c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/hiddenClass/sinceKotlinMultipleClasses.fir.kt
@@ -0,0 +1,47 @@
+// !API_VERSION: 1.0
+// MODULE: m1
+// FILE: a.kt
+
+package p1
+
+@SinceKotlin("1.1")
+class A(val v1: Unit)
+
+// MODULE: m2
+// FILE: b.kt
+
+package p2
+
+@SinceKotlin("1.1")
+class A(val v2: Unit)
+
+// MODULE: m3
+// FILE: c.kt
+
+package p3
+
+@SinceKotlin("1.1")
+class A(val v3: Unit)
+
+// MODULE: m4(m1, m2, m3)
+// FILE: oneExplicitImportOtherStars.kt
+import p1.*
+import p2.A
+import p3.*
+
+fun test(a: A) {
+    a.<!UNRESOLVED_REFERENCE!>v1<!>
+    a.v2
+    a.<!UNRESOLVED_REFERENCE!>v3<!>
+}
+
+// FILE: severalStarImports.kt
+import p1.*
+import p2.*
+import p3.*
+
+fun test(a: A) {
+    a.v1
+    a.<!UNRESOLVED_REFERENCE!>v2<!>
+    a.<!UNRESOLVED_REFERENCE!>v3<!>
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/internal.fir.kt b/compiler/testData/diagnostics/tests/multimodule/internal.fir.kt
new file mode 100644
index 00000000000..d22b0c4034b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/internal.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A {
+    internal val a = A()
+    internal var v = A()
+    internal fun a() = A()
+    internal inner class B
+}
+
+internal val a = A()
+internal var v = A()
+internal fun a() = A()
+internal class B
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    val _a = <!INAPPLICABLE_CANDIDATE!>a<!>
+    val _v = <!INAPPLICABLE_CANDIDATE!>v<!>
+    <!INAPPLICABLE_CANDIDATE!>a<!>()
+    <!INAPPLICABLE_CANDIDATE!>B<!>()
+
+    val inst = A()
+    val ia = inst.<!INAPPLICABLE_CANDIDATE!>a<!>
+    val iv = inst.<!INAPPLICABLE_CANDIDATE!>v<!>
+    inst.<!INAPPLICABLE_CANDIDATE!>a<!>()
+    inst.<!INAPPLICABLE_CANDIDATE!>B<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/kt14249.fir.kt b/compiler/testData/diagnostics/tests/multimodule/kt14249.fir.kt
new file mode 100644
index 00000000000..cbcb03b507a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/kt14249.fir.kt
@@ -0,0 +1,20 @@
+// MODULE: m1
+// FILE: test/Foo.java
+
+package test;
+
+class Foo {
+    static Foo create() { return Foo(); }
+    void takeFoo(Foo f) {}
+}
+
+// MODULE: m2(m1)
+// FILE: test.kt
+
+package test
+
+fun test() {
+    Foo()
+    val a: Foo = Foo.create()
+    Foo().takeFoo(a)
+}
diff --git a/compiler/testData/diagnostics/tests/multimodule/packagePrivate.fir.kt b/compiler/testData/diagnostics/tests/multimodule/packagePrivate.fir.kt
new file mode 100644
index 00000000000..2cc1dbbbe05
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/packagePrivate.fir.kt
@@ -0,0 +1,19 @@
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+private val a = 1
+
+// FILE: b.kt
+
+package p
+
+val b = <!INAPPLICABLE_CANDIDATE!>a<!> // same package, same module
+
+// MODULE: m2(m1)
+// FILE: c.kt
+
+package p
+
+val c = <!INAPPLICABLE_CANDIDATE!>a<!> // same package, another module
diff --git a/compiler/testData/diagnostics/tests/multimodule/publishedApiInternal.fir.kt b/compiler/testData/diagnostics/tests/multimodule/publishedApiInternal.fir.kt
new file mode 100644
index 00000000000..6828470cc55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/publishedApiInternal.fir.kt
@@ -0,0 +1,56 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -NOTHING_TO_INLINE
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public class A {
+    @PublishedApi
+    internal val a = A()
+    @PublishedApi
+    internal var v = A()
+    @PublishedApi
+    internal fun a() = A()
+    @PublishedApi
+    internal inner class B
+}
+
+@PublishedApi
+internal val a = A()
+@PublishedApi
+internal var v = A()
+@PublishedApi
+internal fun a() = A()
+@PublishedApi
+internal class B
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+import p.*
+
+fun test() {
+    val _a = <!INAPPLICABLE_CANDIDATE!>a<!>
+    val _v = <!INAPPLICABLE_CANDIDATE!>v<!>
+    <!INAPPLICABLE_CANDIDATE!>a<!>()
+    <!INAPPLICABLE_CANDIDATE!>B<!>()
+
+    val inst = A()
+    val ia = inst.<!INAPPLICABLE_CANDIDATE!>a<!>
+    val iv = inst.<!INAPPLICABLE_CANDIDATE!>v<!>
+    inst.<!INAPPLICABLE_CANDIDATE!>a<!>()
+    inst.<!INAPPLICABLE_CANDIDATE!>B<!>()
+}
+
+inline fun testInline() {
+    val _a = <!INAPPLICABLE_CANDIDATE!>a<!>
+    val _v = <!INAPPLICABLE_CANDIDATE!>v<!>
+    <!INAPPLICABLE_CANDIDATE!>a<!>()
+    <!INAPPLICABLE_CANDIDATE!>B<!>()
+
+    val inst = A()
+    val ia = inst.<!INAPPLICABLE_CANDIDATE!>a<!>
+    val iv = inst.<!INAPPLICABLE_CANDIDATE!>v<!>
+    inst.<!INAPPLICABLE_CANDIDATE!>a<!>()
+    inst.<!INAPPLICABLE_CANDIDATE!>B<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/redundantElseInWhen.fir.kt b/compiler/testData/diagnostics/tests/multimodule/redundantElseInWhen.fir.kt
new file mode 100644
index 00000000000..16e0dd3ddea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/redundantElseInWhen.fir.kt
@@ -0,0 +1,45 @@
+// MODULE: m1
+// FILE: a.kt
+
+package test
+
+enum class E {
+    FIRST
+}
+
+sealed class S
+
+class Derived : S()
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+package other
+
+import test.*
+
+fun foo(e: E) = when (e) {
+    E.FIRST -> 42
+    else -> -42
+}
+
+fun bar(s: S?) = when (s) {
+    is Derived -> "Derived"
+    null -> ""
+    else -> TODO("What?!?!")
+}
+
+fun baz(b: Boolean?) = when (b) {
+    true -> 1
+    false -> 0
+    null -> -1
+    // Still warning
+    else -> TODO()
+}
+
+fun baz(b: Boolean) = when (b) {
+    true -> 1
+    false -> 0
+    // Still warning
+    else -> TODO()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multimodule/varargConflict.fir.kt b/compiler/testData/diagnostics/tests/multimodule/varargConflict.fir.kt
new file mode 100644
index 00000000000..0631d24ad78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multimodule/varargConflict.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+
+package p
+
+public fun foo(a: Int) {}
+public fun foo(vararg values: Int) {}
+
+// MODULE: m2
+// FILE: b.kt
+
+package p
+
+public fun foo(a: Int) {}
+public fun foo(vararg values: Int) {}
+
+// MODULE: m3(m1, m2)
+// FILE: c.kt
+package m
+
+import p.foo
+
+fun main() {
+    foo(12)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.fir.kt
new file mode 100644
index 00000000000..550215ec4b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationArgumentEquality.fir.kt
@@ -0,0 +1,89 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+import kotlin.reflect.KClass
+
+expect annotation class Primitives(
+    val z: Boolean = true,
+    val c: Char = 'c',
+    val b: Byte = 42.toByte(),
+    val s: Short = (-1).toShort(),
+    val i: Int = -42,
+    val f: Float = 2.72f,
+    val j: Long = 123456789123456789L,
+    val d: Double = 3.14159265358979
+)
+
+expect annotation class PrimitiveArrays(
+    val z: BooleanArray = [true],
+    val c: CharArray = ['c'],
+    val b: ByteArray = [42.toByte()],
+    val s: ShortArray = [(-1).toShort()],
+    val i: IntArray = [-42],
+    val f: FloatArray = [2.72f],
+    val j: LongArray = [123456789123456789L],
+    val d: DoubleArray = [3.14159265358979]
+)
+
+enum class En { A, B }
+
+annotation class Anno(val value: String = "Anno")
+
+expect annotation class Classes(
+    val s: String = "OK",
+    val e: En = En.B,
+    // TODO: this does not work at the moment because AnnotationDescriptor subclasses do not implement equals correctly
+    // val a: Anno = Anno(),
+    val k: KClass<*> = List::class
+)
+
+expect annotation class ClassArrays(
+    val s: Array<String> = ["OK"],
+    val e: Array<En> = [En.B],
+    // val a: Array<Anno> = [Anno()],
+    val k: Array<KClass<*>> = [List::class],
+    vararg val v: Int = [42]
+)
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+import kotlin.reflect.KClass
+
+actual annotation class Primitives(
+    actual val z: Boolean = true,
+    actual val c: Char = 'c',
+    actual val b: Byte = 42.toByte(),
+    actual val s: Short = (-1).toShort(),
+    actual val i: Int = -42,
+    actual val f: Float = 2.72f,
+    actual val j: Long = 123456789123456789L,
+    actual val d: Double = 3.14159265358979
+)
+
+actual annotation class PrimitiveArrays(
+    actual val z: BooleanArray = [true],
+    actual val c: CharArray = ['c'],
+    actual val b: ByteArray = [42.toByte()],
+    actual val s: ShortArray = [(-1).toShort()],
+    actual val i: IntArray = [-42],
+    actual val f: FloatArray = [2.72f],
+    actual val j: LongArray = [123456789123456789L],
+    actual val d: DoubleArray = [3.14159265358979]
+)
+
+actual annotation class Classes(
+    actual val s: String = "OK",
+    actual val e: En = En.B,
+    // actual val a: Anno = Anno(),
+    actual val k: KClass<*> = List::class
+)
+
+actual annotation class ClassArrays(
+    actual val s: Array<String> = ["OK"],
+    actual val e: Array<En> = [En.B],
+    // actual val a: Array<Anno> = [Anno()],
+    actual val k: Array<KClass<*>> = [List::class],
+    actual vararg val v: Int = [42]
+)
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotations.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotations.fir.kt
new file mode 100644
index 00000000000..80ee3795709
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotations.fir.kt
@@ -0,0 +1,33 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect annotation class A1(val x: Int, val y: String = "OK")
+
+expect annotation class A2(val x: Int = 42, val y: String = "OK")
+
+expect annotation class A3(val x: Int, val y: String)
+
+expect annotation class A4(val x: Int = 42, val y: String)
+
+expect annotation class A5(val x: Int = 42, val y: String)
+
+@A1(0)
+@A2
+@A3(0, "")
+@A4(0, "")
+@A5(0, "")
+fun test() {}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual annotation class A1(actual val x: Int, actual val y: String)
+
+actual annotation class A2(actual val x: Int, actual val y: String = "OK")
+
+actual annotation class A3(actual val x: Int = 42, actual val y: String = "OK")
+
+actual annotation class A4(actual val x: Int, actual val y: String = "OK")
+
+actual annotation class A5(actual val x: Int = 239, actual val y: String = "OK")
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias.fir.kt
new file mode 100644
index 00000000000..0fdad4b88fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias.fir.kt
@@ -0,0 +1,64 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect annotation class A1(val x: Int, val y: String = "OK")
+
+expect annotation class A2(val x: Int = 42, val y: String = "OK")
+
+expect annotation class A3(val x: Int, val y: String)
+
+expect annotation class A4(val x: Int = 42, val y: String)
+
+expect annotation class A5(val x: Int = 42, val y: String)
+
+@A1(0)
+@A2
+@A3(0, "")
+@A4(0, "")
+@A5(0, "")
+fun test() {}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual typealias A1 = J1
+actual typealias A2 = J2
+actual typealias A3 = J3
+actual typealias A4 = J4
+actual typealias A5 = J5
+
+// FILE: J1.java
+
+public @interface J1 {
+    int x();
+    String y();
+}
+
+// FILE: J2.java
+
+public @interface J2 {
+    int x();
+    String y() default "OK";
+}
+
+// FILE: J3.java
+
+public @interface J3 {
+    int x() default 42;
+    String y() default "OK";
+}
+
+// FILE: J4.java
+
+public @interface J4 {
+    int x();
+    String y() default "OK";
+}
+
+// FILE: J5.java
+
+public @interface J5 {
+    int x() default 239;
+    String y() default "OK";
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias2.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias2.fir.kt
new file mode 100644
index 00000000000..71e75036b5c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias2.fir.kt
@@ -0,0 +1,79 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+// See also compiler/testData/codegen/boxAgainstJava/multiplatform/annotationsViaActualTypeAliasFromBinary.kt
+
+import kotlin.reflect.KClass
+
+expect annotation class Anno(
+    val b: Byte = 1.toByte(),
+    val c: Char = 'x',
+    val d: Double = 3.14,
+    val f: Float = -2.72f,
+    val i: Int = 42424242,
+    val i2: Int = 53535353,
+    val j: Long = 239239239239239L,
+    val j2: Long = 239239L,
+    val s: Short = 42.toShort(),
+    val z: Boolean = true,
+    val ba: ByteArray = [(-1).toByte()],
+    val ca: CharArray = ['y'],
+    val da: DoubleArray = [-3.14159],
+    val fa: FloatArray = [2.7218f],
+    val ia: IntArray = [424242],
+    val ja: LongArray = [239239239239L, 239239L],
+    val sa: ShortArray = [(-43).toShort()],
+    val za: BooleanArray = [false, true],
+    val str: String = "fizz",
+    val k: KClass<*> = Number::class,
+    val e: E = E.E1,
+    // TODO: val a: A = A("1"),
+    val stra: Array<String> = ["bu", "zz"],
+    val ka: Array<KClass<*>> = [Double::class, String::class, LongArray::class, Array<Array<Array<Int>>>::class, Unit::class],
+    val ea: Array<E> = [E.E2, E.E3]
+    // TODO: val aa: Array<A> = [A("2"), A("3")]
+)
+
+enum class E { E1, E2, E3 }
+
+annotation class A(val value: String)
+
+@Anno
+fun test() {}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual typealias Anno = Jnno
+
+// FILE: Jnno.java
+
+public @interface Jnno {
+    byte b() default 1;
+    char c() default 'x';
+    double d() default 3.14;
+    float f() default -2.72f;
+    int i() default 42424242;
+    int i2() default 21212121 + 32323232;
+    long j() default 239239239239239L;
+    long j2() default 239239;
+    short s() default 42;
+    boolean z() default true;
+    byte[] ba() default {-1};
+    char[] ca() default {'y'};
+    double[] da() default {-3.14159};
+    float[] fa() default {2.7218f};
+    int[] ia() default {424242};
+    long[] ja() default {239239239239L, 239239};
+    short[] sa() default {-43};
+    boolean[] za() default {false, true};
+    String str() default "fi" + "zz";
+    Class<?> k() default Number.class;
+    E e() default E.E1;
+    // TODO: A a() default @A("1");
+    String[] stra() default {"bu", "zz"};
+    Class<?>[] ka() default {double.class, String.class, long[].class, Integer[][][].class, void.class};
+    E[] ea() default {E.E2, E.E3};
+    // TODO: A[] aa() default {@A("2"), @A("3")};
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/constructor.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/constructor.fir.kt
new file mode 100644
index 00000000000..d801d2363de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/constructor.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Ok(x: Int, y: String = "")
+
+expect class FailX(x: Int, y: String = "")
+
+expect class FailY(x: Int, y: String = "")
+
+fun test() {
+    Ok(42)
+    Ok(42, "OK")
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class Ok actual constructor(x: Int, y: String)
+
+actual class FailX actual constructor(x: Int = 0, y: String)
+
+actual class FailY actual constructor(x: Int, y: String = "")
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedDeclaresDefaultArguments.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedDeclaresDefaultArguments.fir.kt
new file mode 100644
index 00000000000..fbf064e3270
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedDeclaresDefaultArguments.fir.kt
@@ -0,0 +1,41 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun ok(x: Int, y: String = "")
+
+expect fun failX(x: Int, y: String = "")
+
+expect fun failY(x: Int, y: String = "")
+
+expect open class Foo {
+    fun ok(x: Int, y: String = "")
+
+    fun failX(x: Int, y: String = "")
+
+    fun failY(x: Int, y: String = "")
+}
+
+fun test(foo: Foo) {
+    ok(42)
+    ok(42, "OK")
+    foo.ok(42)
+    foo.ok(42, "OK")
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual fun ok(x: Int, y: String) {}
+
+actual fun failX(x: Int = 0, y: String) {}
+
+actual fun failY(x: Int, y: String = "") {}
+
+actual open class Foo {
+    actual fun ok(x: Int, y: String) {}
+
+    actual fun failX(x: Int = 0, y: String) {}
+
+    actual fun failY(x: Int, y: String = "") {}
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedInheritsDefaultArguments.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedInheritsDefaultArguments.fir.kt
new file mode 100644
index 00000000000..1fb2506bad2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedInheritsDefaultArguments.fir.kt
@@ -0,0 +1,37 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface Foo {
+    fun ok(x: Int, y: String = "")
+
+    fun failX(x: Int, y: String = "")
+
+    fun failY(x: Int, y: String = "")
+}
+
+expect class Bar : Foo {
+    override fun ok(x: Int, y: String)
+
+    override fun failX(x: Int, y: String)
+
+    override fun failY(x: Int, y: String)
+}
+
+fun test(foo: Foo, bar: Bar) {
+    foo.ok(42)
+    foo.ok(42, "OK")
+    bar.ok(42)
+    bar.ok(42, "OK")
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class Bar : Foo {
+    actual override fun ok(x: Int, y: String) {}
+    
+    actual override fun failX(x: Int = 0, y: String) {}
+
+    actual override fun failY(x: Int, y: String = "") {}
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedVsNonExpectedWithDefaults.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedVsNonExpectedWithDefaults.fir.kt
new file mode 100644
index 00000000000..b77b263b686
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedVsNonExpectedWithDefaults.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun ok(x: Int, y: String = "")
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual fun ok(x: Int, y: String) {}
+
+fun ok(x: Int, y: Long = 1L) {}
+
+fun test() {
+    ok(1)
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/deprecated/header.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/deprecated/header.fir.kt
new file mode 100644
index 00000000000..04c968e8d9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/deprecated/header.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+header class My
+
+header fun foo(): Int
+
+header val x: String
+
+header object O
+
+header enum class E {
+    FIRST
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+impl class My
+
+impl fun foo() = 42
+
+impl val x get() = "Hello"
+
+impl object O
+
+impl enum class E {
+    FIRST
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/enum/additionalEntriesInImpl.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/enum/additionalEntriesInImpl.fir.kt
new file mode 100644
index 00000000000..0fdbc9c2816
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/enum/additionalEntriesInImpl.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect enum class Foo { A, B }
+expect enum class Bar { X, Y, Z }
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual enum class Foo { A, B, C, D, E }
+actual enum class Bar { V, X, W, Y, Z }
diff --git a/compiler/testData/diagnostics/tests/multiplatform/enum/constructorInHeaderEnum.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/enum/constructorInHeaderEnum.fir.kt
new file mode 100644
index 00000000000..635e8e827d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/enum/constructorInHeaderEnum.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect enum class En(x: Int) {
+    E1,
+    E2(42),
+    ;
+
+    <!INAPPLICABLE_CANDIDATE!>constructor(s: String)<!>
+}
+
+expect enum class En2 {
+    E1()
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/enum/differentEntryOrder.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/enum/differentEntryOrder.fir.kt
new file mode 100644
index 00000000000..a0928c8d2ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/enum/differentEntryOrder.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect enum class Foo { A, B }
+expect enum class Bar { X, Y, Z }
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual enum class Foo { B, A }
+actual enum class Bar { X, Z, Y }
diff --git a/compiler/testData/diagnostics/tests/multiplatform/enum/enumEntryWithBody.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/enum/enumEntryWithBody.fir.kt
new file mode 100644
index 00000000000..0e3986250ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/enum/enumEntryWithBody.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect enum class En {
+    E1,
+    E2 {
+        fun foo() = ""
+    },
+    E3 { };
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/enum/javaEnum.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/enum/javaEnum.fir.kt
new file mode 100644
index 00000000000..5072b4f2cd8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/enum/javaEnum.fir.kt
@@ -0,0 +1,32 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect enum class Foo {
+    ENTRY
+}
+
+expect enum class _TimeUnit
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual typealias Foo = FooImpl
+
+actual typealias _TimeUnit = java.util.concurrent.TimeUnit
+
+// FILE: FooImpl.java
+public enum FooImpl {
+    ENTRY("OK") {
+        @Override
+        public String getResult() {
+            return value;
+        }
+    };
+
+    protected final String value;
+
+    public FooImpl(String value) {
+        this.value = value;
+    }
+
+    public abstract String getResult();
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/enum/simpleEnum.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/enum/simpleEnum.fir.kt
new file mode 100644
index 00000000000..853f3029a2c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/enum/simpleEnum.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect enum class Foo {
+    ENTRY1,
+    ENTRY2,
+    ENTRY3;
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual enum class Foo(val x: String) {
+    ENTRY1("1"),
+    ENTRY2("2"),
+    ENTRY3("3");
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/generic/functionTypeParameterBounds.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/generic/functionTypeParameterBounds.fir.kt
new file mode 100644
index 00000000000..8023137fd55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/generic/functionTypeParameterBounds.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun <T : Comparable<T>> Array<out T>.sort(): Unit
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual fun <T : Comparable<T>> Array<out T>.sort(): Unit {}
+
+fun <T> Array<out T>.sort(): Unit {}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/generic/genericMemberBounds.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/generic/genericMemberBounds.fir.kt
new file mode 100644
index 00000000000..e13adfe8d64
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/generic/genericMemberBounds.fir.kt
@@ -0,0 +1,25 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class A {
+    fun <T : Any> foo(): Unit
+
+    fun <S : Comparable<S>> bar(): List<S>
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual typealias A = JavaA
+
+// FILE: JavaA.java
+import java.util.List;
+
+public class JavaA {
+    public <T> void foo() {}
+
+    public <S extends Comparable<S>> List<S> bar() {
+        return null;
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/generic/membersInGenericClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/generic/membersInGenericClass.fir.kt
new file mode 100644
index 00000000000..109e6652f72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/generic/membersInGenericClass.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect interface A<T> {
+    val x: T
+    var y: List<T>
+    fun f(p: Collection<T>): Map<T, A<T?>>
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual interface A<T> {
+    actual val x: T
+    actual var y: List<T>
+    actual fun f(p: Collection<T>): Map<T, A<T?>>
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/generic/typeParameterBoundsDifferentOrderActualMissing.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/generic/typeParameterBoundsDifferentOrderActualMissing.fir.kt
new file mode 100644
index 00000000000..309c8d14dce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/generic/typeParameterBoundsDifferentOrderActualMissing.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface A
+interface B
+
+expect fun <T> List<T>.foo() where T : A, T : B
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+fun <T> List<T>.foo() where T : B, T : A {}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDefaultValuesInAnnotationViaTypealias.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDefaultValuesInAnnotationViaTypealias.fir.kt
new file mode 100644
index 00000000000..f632ea1d20c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDefaultValuesInAnnotationViaTypealias.fir.kt
@@ -0,0 +1,48 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect annotation class Foo1
+expect annotation class Foo2
+expect annotation class Foo3
+expect annotation class Foo4
+expect annotation class Foo5()
+expect annotation class Foo6()
+expect annotation class Foo7()
+
+@Foo1
+fun foo() {}
+
+@Foo5
+fun bar() {}
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: Bar1.java
+
+public @interface Bar1 {
+    String value() default "";
+}
+
+// FILE: Bar2.java
+
+public @interface Bar2 {
+    String value() default "";
+    String path();
+}
+
+// FILE: jvm.kt
+
+actual typealias Foo1 = Bar1
+
+actual typealias Foo4 = Bar2
+
+actual annotation class Foo2(val p: String = "default")
+
+actual annotation class Foo3(val a: String = "a", val b: String = "b")
+
+actual annotation class Foo5
+
+actual annotation class Foo6(val s: String = "value")
+
+actual typealias Foo7 = Bar2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDifferentConstructors.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDifferentConstructors.fir.kt
new file mode 100644
index 00000000000..d9998d3d679
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualClassWithDifferentConstructors.fir.kt
@@ -0,0 +1,55 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo1
+expect class Foo2
+expect class Foo3
+
+expect class Bar1()
+expect class Bar2()
+expect class Bar3()
+expect class Bar4()
+expect class Bar5()
+expect class Bar6()
+expect class Bar7(s: String)
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: JavaFoo.java
+
+public class JavaFoo {
+    public JavaFoo(int i) {}
+}
+
+// FILE: JavaBar.java
+
+public class JavaBar {
+    public JavaBar(int i) {}
+}
+
+// FILE: jvm.kt
+
+actual class Foo1(val s: String)
+actual class Foo2(val p: String = "value", i: Int)
+actual typealias Foo3 = JavaFoo
+
+actual class Bar1(val s: String)
+actual class Bar2(val p: String = "value", i: Int)
+actual typealias Bar3 = JavaBar
+actual class Bar4(val s: String) {
+    constructor() : this("")
+}
+
+actual class Bar5 {
+    actual constructor()
+    constructor(s: String)
+}
+
+class Bar6 {
+    actual constructor()
+}
+
+actual class Bar7 actual constructor(s: String) {
+    constructor() : this("")
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualMissing.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualMissing.fir.kt
new file mode 100644
index 00000000000..b6b5439476b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/actualMissing.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class A {
+    fun foo()
+}
+
+// MODULE: m1-jvm(m1-common)
+// FILE: jvm.kt
+
+class A {
+    actual fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/baseExpectClassWithoutConstructor.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/baseExpectClassWithoutConstructor.fir.kt
new file mode 100644
index 00000000000..f461354aa08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/baseExpectClassWithoutConstructor.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect open class A
+expect class B : A
+open class C : A
+
+// MODULE: m1-jvm(m1-common)
+// FILE: jvm.kt
+
+actual open class A
+actual class B : A()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/classKinds.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/classKinds.fir.kt
new file mode 100644
index 00000000000..d8f41113255
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/classKinds.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect interface Interface
+
+expect annotation class Anno(val prop: String)
+
+expect object Object
+
+expect class Class
+
+expect enum class En { ENTRY }
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual interface Interface
+
+actual annotation class Anno actual constructor(actual val prop: String)
+
+actual object Object
+
+actual class Class
+
+actual enum class En { ENTRY }
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/dontOverrideMethodsFromInterfaceInCommonCode.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/dontOverrideMethodsFromInterfaceInCommonCode.fir.kt
new file mode 100644
index 00000000000..6aba00b82ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/dontOverrideMethodsFromInterfaceInCommonCode.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface Foo {
+    fun foo()
+}
+
+expect class ImplicitFoo : Foo
+
+expect class ExplicitFoo : Foo {
+    override fun foo()
+}
+
+expect class ImplicitFooCheck : Foo
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class ImplicitFoo : Foo {
+    override fun foo() {}
+}
+
+actual class ExplicitFoo : Foo {
+    actual override fun foo() {}
+}
+
+actual class ImplicitFooCheck : Foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectClassWithExplicitAbstractMember.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectClassWithExplicitAbstractMember.fir.kt
new file mode 100644
index 00000000000..901cb01a6d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectClassWithExplicitAbstractMember.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface Foo {
+    fun foo()
+}
+
+expect class NonAbstractClass : Foo {
+    abstract fun bar()
+
+    abstract val baz: Int
+
+    abstract override fun foo()
+}
+
+expect abstract class AbstractClass : Foo {
+    abstract fun bar()
+
+    abstract val baz: Int
+
+    abstract override fun foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectClassWithoutConstructor.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectClassWithoutConstructor.fir.kt
new file mode 100644
index 00000000000..cf76d6cbf37
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectClassWithoutConstructor.fir.kt
@@ -0,0 +1,25 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo
+expect class Bar()
+expect class Baz constructor()
+expect class FooBar {
+    constructor()
+}
+
+fun test() {
+    Foo()
+    Bar()
+    Baz()
+    FooBar()
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class Foo
+actual class Bar
+actual class Baz
+actual class FooBar
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectDeclarationWithStrongIncompatibilities.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectDeclarationWithStrongIncompatibilities.fir.kt
new file mode 100644
index 00000000000..615437435a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectDeclarationWithStrongIncompatibilities.fir.kt
@@ -0,0 +1,33 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo1(x: Int)
+expect fun foo2(x: Int)
+
+expect class NoArgConstructor()
+
+expect fun foo3(): Int
+expect fun foo4(): Int
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: jvm.kt
+
+actual fun foo1(x: Int) {}
+
+fun foo1(x: Int, y: Int) {}
+fun foo1(x: String) {}
+
+fun foo2(x: Int, y: Int) {}
+fun foo2(x: String) {}
+
+actual fun foo3(): String = ""
+fun foo4(x: Int): String = ""
+
+actual class NoArgConstructor {
+    actual constructor()
+    actual constructor(x: Int)
+    constructor(x: String)
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectDeclarationWithWeakIncompatibilities.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectDeclarationWithWeakIncompatibilities.fir.kt
new file mode 100644
index 00000000000..e51224eba3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectDeclarationWithWeakIncompatibilities.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo1
+expect class Foo2
+
+expect fun foo2(): Int
+
+expect val s: String
+
+expect open class Foo3
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: jvm.kt
+
+interface Foo1
+actual interface Foo2
+
+actual var s: String = "value"
+
+fun foo2(): Int = 0
+
+actual class Foo3
+
+class Foo3
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectFinalActualOpen.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectFinalActualOpen.fir.kt
new file mode 100644
index 00000000000..63088d416ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/expectFinalActualOpen.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    fun f()
+    val v: String
+}
+
+expect class Bar {
+    fun g()
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual open class Foo(actual open val v: String) {
+    actual open fun f() {}
+}
+
+actual typealias Bar = JavaBar
+
+// FILE: JavaBar.java
+
+public class JavaBar {
+    public void g() {}
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/explicitConstructorDelegation.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/explicitConstructorDelegation.fir.kt
new file mode 100644
index 00000000000..c5b897ca5db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/explicitConstructorDelegation.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect open class A {
+    constructor(s: String)
+
+    constructor(n: Number) : this("A")
+}
+
+expect class B : A {
+    constructor(i: Int)
+
+    constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>("B")
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithAbstractMember.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithAbstractMember.fir.kt
new file mode 100644
index 00000000000..58af3847cb9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithAbstractMember.fir.kt
@@ -0,0 +1,62 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect abstract class BaseA() {
+    abstract fun foo()
+}
+expect open class BaseAImpl() : BaseA
+
+class DerivedA1 : BaseAImpl()
+class DerivedA2 : BaseAImpl() {
+    override fun foo() = super.foo()
+}
+
+
+
+expect interface BaseB {
+    fun foo()
+}
+expect open class BaseBImpl() : BaseB
+
+class DerivedB1 : BaseBImpl()
+class DerivedB2 : BaseBImpl() {
+    override fun foo() = super.foo()
+}
+
+
+
+expect interface BaseC {
+    fun foo()
+}
+expect abstract class BaseCImpl() : BaseC
+
+class DerivedC1 : BaseCImpl()
+class DerivedC2 : BaseCImpl() {
+    override fun foo() = super.foo()
+}
+
+
+
+expect interface BaseD {
+    fun foo()
+}
+abstract class BaseDImpl() : BaseD {
+    fun bar() = super.foo()
+}
+
+
+
+expect interface BaseE {
+    fun foo()
+}
+sealed class BaseEImpl() : BaseE {
+    fun bar() = super.foo()
+}
+
+
+
+expect interface BaseF {
+    fun foo()
+}
+expect class BaseFImpl() : BaseF
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithoutExplicitOverrideOfMethod.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithoutExplicitOverrideOfMethod.fir.kt
new file mode 100644
index 00000000000..c2db2cca892
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithoutExplicitOverrideOfMethod.fir.kt
@@ -0,0 +1,36 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect abstract class Base {
+    abstract fun foo()
+}
+
+expect class DerivedImplicit : Base
+
+expect class DerivedExplicit : Base {
+    override fun foo()
+}
+
+expect class DerivedExplicitCheck : Base {
+    override fun foo()
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual abstract class Base {
+    actual abstract fun foo()
+}
+
+actual class DerivedImplicit : Base() {
+    override fun foo() {}
+}
+
+actual class DerivedExplicit : Base() {
+    actual override fun foo() {}
+}
+
+actual class DerivedExplicitCheck : Base() {
+    override fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/extraHeaderOnMembers.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/extraHeaderOnMembers.fir.kt
new file mode 100644
index 00000000000..fe29843bf5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/extraHeaderOnMembers.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class H {
+    expect fun foo()
+}
+
+// MODULE: m1-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class H {
+    actual fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/functionAndPropertyWithSameName.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/functionAndPropertyWithSameName.fir.kt
new file mode 100644
index 00000000000..79af20b647b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/functionAndPropertyWithSameName.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    val bar: String
+}
+
+// MODULE: m1-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class Foo {
+    actual val bar = "bar"
+    fun bar() = bar
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/genericClassImplTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/genericClassImplTypeAlias.fir.kt
new file mode 100644
index 00000000000..f732153f8c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/genericClassImplTypeAlias.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -ACTUAL_WITHOUT_EXPECT
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class C1
+expect interface C2<A>
+expect interface C3<B>
+expect interface C4<D, E>
+expect interface C5<F, G>
+expect interface C6<H>
+expect interface C7<I>
+expect interface C8<J>
+expect interface C9<K>
+expect interface C10<L>
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual typealias C1 = String
+actual typealias C2<A> = List<String>
+actual typealias C3<B> = List<B>
+actual typealias C4<D, E> = MutableMap<D, E>
+actual typealias C5<F, G> = MutableMap<G, F>
+actual typealias C6<H> = MutableList<H>
+actual typealias C7<I> = MutableList<out I>
+actual typealias C8<J> = MutableList<*>
+actual typealias C9<K> = MutableList<in K>
+
+typealias Tmp<K> = MutableList<K>
+actual typealias C10<L> = Tmp<L>
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/headerClassMember.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/headerClassMember.fir.kt
new file mode 100644
index 00000000000..89ac1118e5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/headerClassMember.fir.kt
@@ -0,0 +1,24 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect class Foo {
+    val foo: String
+
+    fun bar(x: Int): Int
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual class Foo {
+    actual val foo: String = "JVM"
+
+    actual fun bar(x: Int): Int = x + 1
+}
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+actual class Foo {
+    actual val foo: String = "JS"
+
+    actual fun bar(x: Int): Int = x - 1
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/headerClassWithFunctionBody.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/headerClassWithFunctionBody.fir.kt
new file mode 100644
index 00000000000..338c52d9816
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/headerClassWithFunctionBody.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect class Foo(
+        val constructorProperty: String,
+        constructorParameter: String
+) {
+    init {
+        "no"
+    }
+
+    constructor(s: String) {
+        "no"
+    }
+
+    constructor() : this("no")
+
+    val prop: String = "no"
+
+    var getSet: String
+        get() = "no"
+        set(value) {}
+
+    fun functionWithBody(x: Int): Int {
+        return x + 1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/implDataClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/implDataClass.fir.kt
new file mode 100644
index 00000000000..06bdbf3b645
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/implDataClass.fir.kt
@@ -0,0 +1,32 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo(x: Int, y: String) {
+    val x: Int
+    val y: String
+}
+
+expect class Bar(z: Double)
+
+expect class Baz(w: List<String>) {
+    val w: List<String>
+
+    operator fun component1(): List<String>
+
+    // Disabled because default arguments are not allowed
+    // fun copy(w: List<T> = ...): Baz<T>
+
+    override fun equals(other: Any?): Boolean
+    override fun hashCode(): Int
+    override fun toString(): String
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual data class Foo actual constructor(actual val x: Int, actual val y: String)
+
+actual data class Bar actual constructor(val z: Double)
+
+actual data class Baz actual constructor(actual val w: List<String>)
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/implOpenClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/implOpenClass.fir.kt
new file mode 100644
index 00000000000..f115edd5638
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/implOpenClass.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo
+
+expect fun getFoo(): Foo
+
+fun <T : Foo> bar() {} // no "Foo is final" warning should be here
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual open class Foo
+
+class Bar : Foo()
+
+actual fun getFoo(): Foo = Bar()
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/inheritanceByDelegationInExpectClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/inheritanceByDelegationInExpectClass.fir.kt
new file mode 100644
index 00000000000..cd03ae5bf0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/inheritanceByDelegationInExpectClass.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface A
+
+class B : A
+expect class Foo(b: B) : A by b
+
+expect class Bar : A by B()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/memberPropertyKinds.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/memberPropertyKinds.fir.kt
new file mode 100644
index 00000000000..cc6004b6ea3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/memberPropertyKinds.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    val justVal: String
+    var justVar: String
+
+    val String.extensionVal: Unit
+    var <T> T.genericExtensionVar: T
+
+    val valWithGet: String
+        get
+    var varWithGetSet: String
+        get set
+
+    val backingFieldVal: String = "no"
+    var backingFieldVar: String = "no"
+
+    val customAccessorVal: String
+    get() = "no"
+    var customAccessorVar: String
+    get() = "no"
+    set(value) {}
+
+    lateinit var lateinitVar: String
+
+    val delegated: String by Delegate
+}
+
+object Delegate { operator fun getValue(x: Any?, y: Any?): String = "" }
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/modalityCheckForExplicitAndImplicitOverride.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/modalityCheckForExplicitAndImplicitOverride.fir.kt
new file mode 100644
index 00000000000..b81079ecae1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/modalityCheckForExplicitAndImplicitOverride.fir.kt
@@ -0,0 +1,35 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo1 {
+    val x: String
+}
+
+expect class Foo2 {
+    val x: String
+}
+
+expect class Foo3 {
+    val x: String
+}
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: jvm.kt
+
+open class Open {
+    open val x = "42"
+}
+
+actual open class Foo1 : Open() {
+    override val x = super.x
+}
+
+actual open class Foo2 : Open()
+
+open class WithFinal {
+    val x = "42"
+}
+
+actual open class Foo3 : WithFinal()
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/morePermissiveVisibilityOnActual.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/morePermissiveVisibilityOnActual.fir.kt
new file mode 100644
index 00000000000..649d8c1888f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/morePermissiveVisibilityOnActual.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// MODULE: m1-common
+// FILE: common.kt
+
+expect open class Container {
+    fun publicFun()
+
+    internal fun internalFun1()
+    internal fun internalFun2()
+    internal fun internalFun3()
+
+    protected fun protectedFun1()
+    protected fun protectedFun2()
+    protected fun protectedFun3()
+
+    open internal fun openInternalFun()
+    open fun openPublicFun()
+}
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: jvm.kt
+
+actual open class Container {
+    actual fun publicFun() {}               // OK: public -> public
+
+    actual fun internalFun1() {}            // OK: internal -> public
+    actual internal fun internalFun2() {}   // OK: internal -> internal
+
+    actual fun protectedFun1() {}           // OK: protected -> public
+    actual protected fun protectedFun2() {} // OK: protected -> protected
+
+    actual internal fun protectedFun3() {}  // BAD: protected -> internal
+    actual protected fun internalFun3() {}  // BAD: internal -> protected
+
+    actual open fun openInternalFun() {}    // BAD: internal+open -> public
+    actual internal fun openPublicFun() {}  // BAD: open+public -> internal
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/morePermissiveVisibilityOnActualViaTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/morePermissiveVisibilityOnActualViaTypeAlias.fir.kt
new file mode 100644
index 00000000000..5a44875cda6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/morePermissiveVisibilityOnActualViaTypeAlias.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// MODULE: m1-common
+// FILE: common.kt
+
+expect open class Container {
+    internal fun internalFun()
+}
+
+// MODULE: m2-jvm(m1-common)
+
+// FILE: foo/Foo.java
+
+package foo;
+
+public class Foo {
+    public final void internalFun() {}    // OK: internal -> public
+}
+
+// FILE: jvm.kt
+
+actual typealias Container = foo.Foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/nestedClasses.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/nestedClasses.fir.kt
new file mode 100644
index 00000000000..ba17319f3dd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/nestedClasses.fir.kt
@@ -0,0 +1,58 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class OuterClass {
+    class NestedClass {
+        class DeepNested {
+            class Another {
+                fun f(s: String)
+                val p: Int
+            }
+        }
+    }
+
+    inner class InnerClass {
+        fun f(x: Int)
+        val p: String
+    }
+
+    companion object
+}
+
+expect class OuterClassWithNamedCompanion {
+    companion object Factory
+}
+
+expect object OuterObject {
+    object NestedObject
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class OuterClass {
+    actual class NestedClass {
+        actual class DeepNested {
+            actual class Another {
+                actual fun f(s: String) {}
+                actual val p: Int = 42
+            }
+        }
+    }
+
+    actual inner class InnerClass {
+        actual fun f(x: Int) {}
+        actual val p: String = ""
+    }
+
+    actual companion object
+}
+
+actual class OuterClassWithNamedCompanion {
+    actual companion object Factory
+}
+
+actual object OuterObject {
+    actual object NestedObject
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/nestedClassesWithErrors.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/nestedClassesWithErrors.fir.kt
new file mode 100644
index 00000000000..8f47be93d20
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/nestedClassesWithErrors.fir.kt
@@ -0,0 +1,46 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class B {
+    class N {
+        fun body() {}
+        expect fun extraHeader()
+    }
+}
+
+expect class C {
+    expect class N
+    expect enum class E
+    expect inner class I
+}
+
+expect class D {
+    class N
+}
+
+expect class E {
+    class N
+}
+
+// MODULE: m1-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class B {
+    actual class N {
+        actual fun body() {}
+        actual fun extraHeader() {}
+    }
+}
+
+actual class C {
+    actual class N
+    actual enum class E
+    actual inner class I
+}
+
+actual class D
+
+actual class E {
+    class N
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/noImplKeywordOnMember.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/noImplKeywordOnMember.fir.kt
new file mode 100644
index 00000000000..b12c5d39467
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/noImplKeywordOnMember.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    fun bar(): String
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class Foo {
+    fun bar(): String = "bar"
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/privateMembers.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/privateMembers.fir.kt
new file mode 100644
index 00000000000..fe2e20bb2ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/privateMembers.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class A {
+    private fun foo()
+    private val bar: String
+    private fun Int.memExt(): Any
+
+    private class Nested
+}
+
+// MODULE: m1-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class A {
+    private fun foo() {}
+    private val bar: String = ""
+    actual private fun Int.memExt(): Any = 0
+
+    actual private class Nested
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/simpleHeaderClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/simpleHeaderClass.fir.kt
new file mode 100644
index 00000000000..d4032bccead
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/simpleHeaderClass.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect class Foo
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual class Foo
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+actual class Foo
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/smartCastOnExpectClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/smartCastOnExpectClass.fir.kt
new file mode 100644
index 00000000000..bb2649aa8ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/smartCastOnExpectClass.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo { // also, it's important that Foo doesn't override equals
+    fun foo()
+}
+
+fun check(x1: Foo, x: Any) {
+    if (x1 == x) {
+        x.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerClass/superClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerClass/superClass.fir.kt
new file mode 100644
index 00000000000..25dafe6fef2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerClass/superClass.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+interface I
+open class C
+interface J
+
+expect class Foo : I, C, J
+
+expect class Bar : C()
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual class Foo : I, C(), J
+
+actual class Bar
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+actual class Foo : I, J, C()
+
+actual class Bar : C()
diff --git a/compiler/testData/diagnostics/tests/multiplatform/headerFunInNonHeaderClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/headerFunInNonHeaderClass.fir.kt
new file mode 100644
index 00000000000..160a0998301
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/headerFunInNonHeaderClass.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+class Foo {
+    expect fun bar(): String
+}
+
+// MODULE: m1-jvm(m1-common)
+// FILE: jvm.kt
diff --git a/compiler/testData/diagnostics/tests/multiplatform/implDelegatedMember.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/implDelegatedMember.fir.kt
new file mode 100644
index 00000000000..9d3e9381025
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/implDelegatedMember.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect open class Foo {
+    open fun bar(): String
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+interface Bar {
+    fun bar(): String
+}
+
+val bar: Bar
+    get() = null!!
+
+actual open class Foo : Bar by bar
diff --git a/compiler/testData/diagnostics/tests/multiplatform/implDynamic.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/implDynamic.fir.kt
new file mode 100644
index 00000000000..8f5f15bc218
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/implDynamic.fir.kt
@@ -0,0 +1,29 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -UNSUPPORTED
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    constructor(p: Any)
+
+    fun f1(s: String): Int
+
+    fun f2(s: List<String>?): MutableMap<Boolean?, Foo>
+
+    fun <T : Set<Number>> f3(t: T): T?
+}
+
+// MODULE: m2-js(m1-common)
+// FILE: js.kt
+
+// TODO: do not suppress UNSUPPORTED once JS files in multi-platform tests are analyzed with JS analyzer facade
+
+actual class Foo {
+    actual constructor(p: dynamic) {}
+
+    actual fun f1(s: dynamic): dynamic = null!!
+
+    actual fun f2(s: dynamic): MutableMap<Boolean?, Foo> = null!!
+
+    actual fun <T : Set<Number>> f3(t: T): dynamic = null!!
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/implFakeOverride.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/implFakeOverride.fir.kt
new file mode 100644
index 00000000000..6b0167213e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/implFakeOverride.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    fun bar(): String
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+open class Bar {
+    fun bar() = "bar"
+}
+
+actual class Foo : Bar()
diff --git a/compiler/testData/diagnostics/tests/multiplatform/incompatibles.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/incompatibles.fir.kt
new file mode 100644
index 00000000000..3c6b058712a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/incompatibles.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +MultiPlatformProjects
+
+header impl class First
+
+header expect class Second
+
+header actual class Third
+
+impl expect class Fourth
+
+impl actual class Fifth
+
+expect actual class Sixth
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/inlineClasses/expectActualInlineClass.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/inlineClasses/expectActualInlineClass.fir.kt
new file mode 100644
index 00000000000..16e9f770049
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/inlineClasses/expectActualInlineClass.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +MultiPlatformProjects, +InlineClasses
+// MODULE: m1-common
+// FILE: common.kt
+
+expect inline class Foo1(val x: Int) {
+    fun bar(): String
+}
+
+expect inline class Foo2(val x: Int)
+
+expect inline class Foo3
+
+expect class NonInlineExpect
+
+expect inline class NonInlineActual(val x: Int)
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual inline class Foo1(val x: Int) {
+    actual fun bar(): String = "Hello"
+}
+actual inline class Foo2(val x: String)
+actual inline class Foo3
+
+actual inline class NonInlineExpect(val x: Int)
+
+actual class NonInlineActual actual constructor(actual val x: Int)
diff --git a/compiler/testData/diagnostics/tests/multiplatform/java/flexibleTypes.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/java/flexibleTypes.fir.kt
new file mode 100644
index 00000000000..0c9ce6637e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/java/flexibleTypes.fir.kt
@@ -0,0 +1,32 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    constructor(p: Any)
+
+    fun f1(s: String): Int
+
+    fun f2(s: List<String>?): MutableMap<Boolean?, Foo>
+
+    fun <T : Set<Number>> f3(t: T): T?
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: FooImpl.java
+
+import java.util.*;
+
+public class FooImpl {
+    public FooImpl(Object p) {}
+
+    public final int f1(String s) { return 0; }
+
+    public final Map<Boolean, FooImpl> f2(List<String> s) { return null; }
+
+    public final <T extends Set<Number>> T f3(T t) { return null; }
+}
+
+// FILE: jvm.kt
+
+actual typealias Foo = FooImpl
diff --git a/compiler/testData/diagnostics/tests/multiplatform/java/parameterNames.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/java/parameterNames.fir.kt
new file mode 100644
index 00000000000..e20079bebaa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/java/parameterNames.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo {
+    fun foo(i: Int, d: Double, f: Float): Unit
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: FooImpl.java
+
+public class FooImpl {
+    public final void foo(int d, double i, float f) {}
+}
+
+// FILE: jvm.kt
+
+actual typealias Foo = FooImpl
diff --git a/compiler/testData/diagnostics/tests/multiplatform/modifierApplicability.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/modifierApplicability.fir.kt
new file mode 100644
index 00000000000..a4fc5ba6c13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/modifierApplicability.fir.kt
@@ -0,0 +1,35 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect typealias Foo = String
+
+class Outer expect constructor() {
+    expect class Nested
+
+    expect init {}
+
+    expect fun foo()
+    expect val bar: Int
+}
+
+fun foo() {
+    expect fun localFun()
+    expect var x = 42
+    expect class Bar
+}
+
+// MODULE: m2-jvm
+// FILE: jvm.kt
+
+class Outer actual constructor() {
+    actual class Nested
+
+    actual init {}
+}
+
+fun foo() {
+    actual fun localFun() {}
+    actual var x = 42
+    actual class Bar
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/namedArguments.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/namedArguments.fir.kt
new file mode 100644
index 00000000000..acd1bb85ef5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/namedArguments.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect class Foo(zzz: Int) {
+    <!INAPPLICABLE_CANDIDATE!>constructor(aaa: Boolean)<!>
+
+    fun f1(xxx: String): String
+}
+
+expect fun f2(xxx: Int)
+
+fun testCommon() {
+    Foo(zzz = 0)
+    val f = Foo(aaa = true)
+    f.f1(xxx = "")
+    f2(xxx = 42)
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual class Foo actual constructor(val aaa: Boolean) {
+    actual constructor(zzz: Int) : this(zzz == 0)
+
+    actual fun f1(xxx: String) = xxx
+}
+
+actual fun f2(xxx: Int) {}
+
+fun testPlatform() {
+    Foo(zzz = 0)
+    val f = Foo(aaa = true)
+    f.f1(xxx = "")
+    f2(xxx = 42)
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/privateTopLevelDeclarations.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/privateTopLevelDeclarations.fir.kt
new file mode 100644
index 00000000000..1b28447d41b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/privateTopLevelDeclarations.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+private expect fun foo()
+private expect val bar: String
+private expect fun Int.memExt(): Any
+
+private expect class Foo
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+private actual fun foo() {}
+private actual val bar: String = ""
+private actual fun Int.memExt(): Any = 0
+
+private actual class Foo
diff --git a/compiler/testData/diagnostics/tests/multiplatform/sealedTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/sealedTypeAlias.fir.kt
new file mode 100644
index 00000000000..8694b547fb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/sealedTypeAlias.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect sealed class Presence {
+    object Online: Presence
+    object Offline: Presence
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual typealias Presence = P
+sealed class P {
+    object Online : P()
+    object Offline : P()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/multiplatform/sealedTypeAliasTopLevel.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/sealedTypeAliasTopLevel.fir.kt
new file mode 100644
index 00000000000..f2f0aab5368
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/sealedTypeAliasTopLevel.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect sealed class Presence
+expect object Online: Presence
+expect object Offline: Presence
+
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual typealias Presence = P
+sealed class P
+actual object Online : P()
+actual object Offline : P()
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/callHeaderFun.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/callHeaderFun.fir.kt
new file mode 100644
index 00000000000..722251b5fc0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/callHeaderFun.fir.kt
@@ -0,0 +1,25 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo(x: Int): Int
+
+fun callFromCommonCode(x: Int) = foo(x)
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual fun foo(x: Int): Int {
+    return x + 1
+}
+
+fun callFromJVM(x: Int) = foo(x)
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+
+actual fun foo(x: Int): Int {
+    return x - 1
+}
+
+fun callFromJS(x: Int) = foo(x)
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/callableReferenceOnExpectFun.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/callableReferenceOnExpectFun.fir.kt
new file mode 100644
index 00000000000..0c3024de2fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/callableReferenceOnExpectFun.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+package test
+
+expect fun foo(): String
+
+fun g(f: () -> String): String = f()
+
+fun test() {
+    g(::foo)
+}
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+package test
+
+@Deprecated("To check that ::foo is resolved to actual fun foo when compiling common+jvm")
+actual fun foo(): String = ""
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/conflictingHeaderDeclarations.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/conflictingHeaderDeclarations.fir.kt
new file mode 100644
index 00000000000..c7b164c9192
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/conflictingHeaderDeclarations.fir.kt
@@ -0,0 +1,8 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo()
+expect fun foo()
+
+expect fun foo(x: Int)
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/conflictingImplDeclarations.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/conflictingImplDeclarations.fir.kt
new file mode 100644
index 00000000000..da6dad9b6c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/conflictingImplDeclarations.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo()
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual fun foo() {}
+actual fun foo() {}
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+
+actual fun foo() {}
+actual fun foo() {}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/functionModifiers.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/functionModifiers.fir.kt
new file mode 100644
index 00000000000..4b5982611b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/functionModifiers.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun external()
+expect fun tailrec()
+expect fun inline()
+expect fun String.unaryMinus(): String
+expect fun String.and(other: String): String
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual external fun external()
+actual tailrec fun tailrec(): Unit = if (true) Unit else tailrec()
+actual inline fun inline() {}
+actual operator fun String.unaryMinus(): String = this
+actual infix fun String.and(other: String): String = this + other
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerAndImplInDIfferentPackages.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerAndImplInDIfferentPackages.fir.kt
new file mode 100644
index 00000000000..c091e129909
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerAndImplInDIfferentPackages.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+package common
+
+expect fun foo()
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+package jvm
+
+actual fun foo() {}
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+package js
+
+actual fun foo() {}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerDeclarationWithBody.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerDeclarationWithBody.fir.kt
new file mode 100644
index 00000000000..dd4f3f56bde
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerDeclarationWithBody.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo()
+
+expect fun foo() {}
+
+expect fun bar() {}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerWithoutImpl.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerWithoutImpl.fir.kt
new file mode 100644
index 00000000000..28299c1d935
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/headerWithoutImpl.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo()
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/implDeclarationWithoutBody.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/implDeclarationWithoutBody.fir.kt
new file mode 100644
index 00000000000..e0a91283d62
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/implDeclarationWithoutBody.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo()
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual fun foo()
+
+actual fun bar()
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/implWithoutHeader.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/implWithoutHeader.fir.kt
new file mode 100644
index 00000000000..fb7e5052f0e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/implWithoutHeader.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-jvm
+// FILE: jvm.kt
+
+actual fun foo() { }
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/inlineFun.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/inlineFun.fir.kt
new file mode 100644
index 00000000000..d398914f60c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/inlineFun.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+inline expect fun inlineFun()
+expect fun nonInlineFun()
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual fun inlineFun() { }
+actual fun nonInlineFun() { }
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+
+actual inline fun inlineFun() { }
+actual inline fun nonInlineFun() { }
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/simpleHeaderFun.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/simpleHeaderFun.fir.kt
new file mode 100644
index 00000000000..a6f7808abf5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/simpleHeaderFun.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect fun foo()
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual fun foo() {}
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+actual fun foo() {}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/valueParameterModifiers.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/valueParameterModifiers.fir.kt
new file mode 100644
index 00000000000..b20033c7e33
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelFun/valueParameterModifiers.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +MultiPlatformProjects
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun f1(s: () -> String)
+expect inline fun f2(s: () -> String)
+expect inline fun f3(noinline s: () -> String)
+
+expect fun f4(s: () -> String)
+expect inline fun f5(s: () -> String)
+expect inline fun f6(crossinline s: () -> String)
+
+expect fun f7(x: Any)
+expect fun f8(vararg x: Any)
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+actual inline fun f1(noinline s: () -> String) {}
+actual inline fun f2(noinline s: () -> String) {}
+actual inline fun f3(s: () -> String) {}
+actual inline fun f4(crossinline s: () -> String) {}
+actual inline fun f5(crossinline s: () -> String) {}
+actual inline fun f6(s: () -> String) {}
+actual fun f7(vararg x: Any) {}
+actual fun f8(x: Any) {}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelProperty/differentKindsOfProperties.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelProperty/differentKindsOfProperties.fir.kt
new file mode 100644
index 00000000000..d4ec1318474
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelProperty/differentKindsOfProperties.fir.kt
@@ -0,0 +1,40 @@
+// !LANGUAGE: +MultiPlatformProjects +LateinitTopLevelProperties
+// MODULE: m1-common
+// FILE: common.kt
+
+expect val justVal: String
+expect var justVar: String
+
+expect val String.extensionVal: Unit
+expect var <T> T.genericExtensionVar: T
+
+expect val valWithGet: String
+    get
+expect var varWithGetSet: String
+    get set
+
+expect var varWithPlatformGetSet: String
+    expect get
+    expect set
+
+expect val backingFieldVal: String = "no"
+expect var backingFieldVar: String = "no"
+
+expect val customAccessorVal: String
+    get() = "no"
+expect var customAccessorVar: String
+    get() = "no"
+    set(value) {}
+
+expect const val constVal: Int
+
+expect lateinit var lateinitVar: String
+
+expect val delegated: String by Delegate
+object Delegate { operator fun getValue(x: Any?, y: Any?): String = "" }
+
+fun test(): String {
+    expect val localVariable: String
+    localVariable = "no"
+    return localVariable
+}
diff --git a/compiler/testData/diagnostics/tests/multiplatform/topLevelProperty/simpleHeaderVar.fir.kt b/compiler/testData/diagnostics/tests/multiplatform/topLevelProperty/simpleHeaderVar.fir.kt
new file mode 100644
index 00000000000..5f0401c080f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/multiplatform/topLevelProperty/simpleHeaderVar.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+expect var foo: String
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+actual var foo: String = "JVM"
+
+// MODULE: m3-js(m1-common)
+// FILE: js.kt
+actual var foo: String = "JS"
diff --git a/compiler/testData/diagnostics/tests/namedArguments/allowForJavaAnnotation.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/allowForJavaAnnotation.fir.kt
new file mode 100644
index 00000000000..86e395e8dbd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/allowForJavaAnnotation.fir.kt
@@ -0,0 +1,12 @@
+// FILE: A.java
+
+public @interface A {
+    int x();
+
+    String y();
+}
+
+// FILE: 1.kt
+
+@A(x = 1, y = "2")
+fun test() {}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArguments1.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArguments1.fir.kt
new file mode 100644
index 00000000000..6620127a9ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArguments1.fir.kt
@@ -0,0 +1,27 @@
+interface A {
+    fun foo(x : Int)
+}
+
+interface B {
+    fun foo(y : Int)
+}
+
+interface C : A, B
+interface D : B, A
+
+fun foo(x : C, y : D){
+    x.foo(x = 0)
+    x.<!INAPPLICABLE_CANDIDATE!>foo<!>(y = 0)
+    y.<!INAPPLICABLE_CANDIDATE!>foo<!>(x = 0)
+    y.foo(y = 0)
+}
+
+abstract class C1 : A, B
+abstract class D1 : A, B
+
+fun bar(x : C1, y : D1){
+    x.foo(x = 0)
+    x.<!INAPPLICABLE_CANDIDATE!>foo<!>(y = 0)
+    y.foo(x = 0)
+    y.<!INAPPLICABLE_CANDIDATE!>foo<!>(y = 0)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArguments2.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArguments2.fir.kt
new file mode 100644
index 00000000000..aae1ca6de24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArguments2.fir.kt
@@ -0,0 +1,24 @@
+interface A {
+    fun foo(a1: Int, a2: Double)
+    fun bar(a1: Int, a2: Double, a3: String)
+    fun baz(a1: Int, a2: Double, a3: String, a4: Int, a5: String)
+}
+
+interface B {
+    fun foo(b1: Int, b2: Double)
+    fun bar(a1: Int, a2: Double, b3: String)
+    fun baz(a1: Int, b2: Double, a3: String, b4: Int, a5: String)
+}
+
+interface C : A, B { // Warning here, this is correct
+}
+
+fun test(c: C) {
+    c.<!INAPPLICABLE_CANDIDATE!>foo<!>(b1 = 1, b2 = 1.0)
+    c.<!INAPPLICABLE_CANDIDATE!>foo<!>(a1 = 1, b2 = 1.0)
+    c.foo(a1 = 1, a2 = 1.0)
+    c.foo(a1 = 1, a2 = 1.0)
+    c.<!INAPPLICABLE_CANDIDATE!>bar<!>(a1 = 1, a2 = 1.0, b3= "")
+    c.<!INAPPLICABLE_CANDIDATE!>baz<!>(a1 = 1, b2 = 1.0, a3 = "", b4 = 2, a5 = "")
+    c.<!INAPPLICABLE_CANDIDATE!>baz<!>(a1 = 1, a2 = 1.0, a3 = "", b4 = 2, a5 = "")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics1.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics1.fir.kt
new file mode 100644
index 00000000000..2ba29a9054f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics1.fir.kt
@@ -0,0 +1,15 @@
+interface A<T> {
+    fun foo(a: T)
+}
+
+interface B {
+    fun foo(b: Int)
+}
+
+interface C : A<Int>, B { // Warning here, this is correct
+}
+
+fun test(c: C) {
+    c.foo(a = 1)
+    c.<!INAPPLICABLE_CANDIDATE!>foo<!>(b = 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics2.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics2.fir.kt
new file mode 100644
index 00000000000..a585e0831b0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics2.fir.kt
@@ -0,0 +1,15 @@
+interface A {
+    fun <E> foo(a: E)
+}
+
+interface B {
+    fun <T> foo(b: T)
+}
+
+interface C : A, B { // Warning here, this is correct
+}
+
+fun test(c: C) {
+    c.foo(a = 1)
+    c.<!INAPPLICABLE_CANDIDATE!>foo<!>(b = 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics3.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics3.fir.kt
new file mode 100644
index 00000000000..f75dd574cf5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/ambiguousNamedArgumentsWithGenerics3.fir.kt
@@ -0,0 +1,15 @@
+interface A<T> {
+    fun foo(a: T)
+}
+
+interface B<E> {
+    fun foo(b: E)
+}
+
+interface C<U> : A<U>, B<U> { // Warning here, this is correct
+}
+
+fun test(c: C<Int>) {
+    c.foo(a = 1)
+    c.<!INAPPLICABLE_CANDIDATE!>foo<!>(b = 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/namedArguments/disallowForJavaConstructor.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/disallowForJavaConstructor.fir.kt
new file mode 100644
index 00000000000..609f9cb2316
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/disallowForJavaConstructor.fir.kt
@@ -0,0 +1,9 @@
+// FILE: A.java
+
+public class A {
+    public A(int x, String y) {}
+}
+
+// FILE: 1.kt
+
+val test = A(x = 1, y = "2")
diff --git a/compiler/testData/diagnostics/tests/namedArguments/disallowForJavaMethods.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/disallowForJavaMethods.fir.kt
new file mode 100644
index 00000000000..5cdaa97f87a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/disallowForJavaMethods.fir.kt
@@ -0,0 +1,27 @@
+// FILE: JavaSuperClass.java
+
+public class JavaSuperClass {
+    public void foo(int javaName) {}
+
+    public void multipleParameters(int first, long second, String third) {}
+}
+
+// FILE: 1.kt
+
+fun directInvocation() = JavaSuperClass().foo(javaName = 1)
+
+open class KotlinSubClass : JavaSuperClass()
+
+fun viaFakeOverride() = KotlinSubClass().foo(javaName = 2)
+
+class KotlinSubSubClass : KotlinSubClass() {
+    override fun foo(kotlinName: Int) {}
+}
+
+fun viaRealOverride() = KotlinSubSubClass().foo(kotlinName = 3)
+
+
+fun unresolvedParameter() = JavaSuperClass().<!INAPPLICABLE_CANDIDATE!>foo<!>(nonexistentName = 4)
+
+
+fun multipleParameters() = JavaSuperClass().multipleParameters(first = 1, second = 2L, third = "3")
diff --git a/compiler/testData/diagnostics/tests/namedArguments/disallowForSamAdapterConstructor.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/disallowForSamAdapterConstructor.fir.kt
new file mode 100644
index 00000000000..be0da77be10
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/disallowForSamAdapterConstructor.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// FILE: test/J.java
+
+package test;
+
+public class J {
+    public J(String s, Runnable r, Boolean z) {
+    }
+}
+
+// FILE: usage.kt
+
+package test
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>J<!>("", r = { }, z = false)
+}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/disallowForSamAdapterFunction.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/disallowForSamAdapterFunction.fir.kt
new file mode 100644
index 00000000000..df2330f04be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/disallowForSamAdapterFunction.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// FILE: test/J.java
+
+package test;
+
+public class J {
+    public static void foo(String s, Runnable r, Boolean z) {
+    }
+}
+
+// FILE: usage.kt
+
+package test
+
+fun test() {
+    J.foo("", r = { }, z = false)
+}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/defaults.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/defaults.fir.kt
new file mode 100644
index 00000000000..638026dae9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/defaults.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +NewInference +MixedNamedArgumentsInTheirOwnPosition
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+
+fun foo(
+    p1: Int = 1,
+    p2: String = "",
+    p3: Double = 3.0,
+    p4: Char = '4'
+) {}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, "2", 3.0)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p2 = "2", 3.0)
+    foo(1, "2", p3 = 3.0)
+
+    foo(p1 = 1)
+    foo(1, p2 = "2")
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, p2 = "2", 3.0)
+
+    foo()
+    foo(1, p2 = "")
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p3 = 4.0, '4')
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, "")
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, 3.0)
+}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/disabledFeature.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/disabledFeature.fir.kt
new file mode 100644
index 00000000000..63d48fa62a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/disabledFeature.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference -MixedNamedArgumentsInTheirOwnPosition
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+
+fun foo(
+    p1: Int,
+    p2: String,
+    p3: Double
+) {}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, "2", 3.0)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p2 = "2", 3.0)
+    foo(1, "2", p3 = 3.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, p2 = "2", 3.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, "")
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, 3.0)
+}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/oldInference.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/oldInference.fir.kt
new file mode 100644
index 00000000000..080d5086720
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/oldInference.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: -NewInference +MixedNamedArgumentsInTheirOwnPosition
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+
+fun foo(
+    p1: Int,
+    p2: String,
+    p3: Double
+) {}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, "2", 3.0)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p2 = "2", 3.0)
+    foo(1, "2", p3 = 3.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, p2 = "2", 3.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, "")
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, 3.0)
+}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/simple.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/simple.fir.kt
new file mode 100644
index 00000000000..eb0a087d90d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/simple.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference +MixedNamedArgumentsInTheirOwnPosition
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+
+fun foo(
+    p1: Int,
+    p2: String,
+    p3: Double
+) {}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, "2", 3.0)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p2 = "2", 3.0)
+    foo(1, "2", p3 = 3.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(p1 = 1, p2 = "2", 3.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, "")
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, p3 = 2.0, 3.0)
+}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/varargs.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/varargs.fir.kt
new file mode 100644
index 00000000000..068fd00c589
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/mixedNamedPosition/varargs.fir.kt
@@ -0,0 +1,57 @@
+// !LANGUAGE: +NewInference +MixedNamedArgumentsInTheirOwnPosition
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+
+fun foo1(
+    vararg p1: Int,
+    p2: String,
+    p3: Double
+) {}
+
+fun foo2(
+    p1: Int,
+    vararg p2: String,
+    p3: Double
+) {}
+
+fun foo3(
+    p1: Int,
+    p2: String,
+    vararg p3: Double
+) {}
+
+fun foo4(
+    p1: Int,
+    vararg p2: String,
+    p3: Double,
+    p4: Int
+) {}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>foo1<!>(1, 2, p2 = "3", 4.0)
+    <!INAPPLICABLE_CANDIDATE!>foo1<!>(p1 = *intArrayOf(1, 2), "3", p3 = 4.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo1<!>(p2 = "3", 4.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo2<!>(p1 = 1, "2", "3", p3 = 4.0)
+    <!INAPPLICABLE_CANDIDATE!>foo2<!>(1, p2 = *arrayOf("2", "3"), 4.0)
+    foo2(1, p3 = 3.0)
+
+    <!INAPPLICABLE_CANDIDATE!>foo3<!>(p1 = 1, "2", 3.0, 4.0)
+    <!INAPPLICABLE_CANDIDATE!>foo3<!>(p1 = 1, "2", p3 = *doubleArrayOf(3.0, 4.0))
+
+    <!INAPPLICABLE_CANDIDATE!>foo4<!>(p1 = 1, "2", "3", p3 = 4.0, 5)
+    <!INAPPLICABLE_CANDIDATE!>foo4<!>(1, "2", "3", p3 = 4.0, 5)
+    <!INAPPLICABLE_CANDIDATE!>foo4<!>(1, p3 = 4.0, 5)
+
+    <!INAPPLICABLE_CANDIDATE!>foo1<!>(1, 2, p3 = 3.0, "4")
+    foo1(1, 2, p3 = 3.0, p2 = "4")
+    foo1(*intArrayOf(1, 2), p3 = 3.0, p2 = "4")
+
+    <!INAPPLICABLE_CANDIDATE!>foo2<!>(1, p3 = 2.0, "4")
+    <!INAPPLICABLE_CANDIDATE!>foo2<!>(1, p3 = 2.0, *arrayOf("3", "4"))
+    foo2(1, p3 = 2.0, p2 = *arrayOf("3", "4"))
+
+    <!INAPPLICABLE_CANDIDATE!>foo3<!>(1, p3 = *doubleArrayOf(2.0, 3.0), "4")
+    foo3(1, p3 = *doubleArrayOf(2.0, 3.0), p2 = "4")
+}
diff --git a/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsAndDefaultValues.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsAndDefaultValues.fir.kt
new file mode 100644
index 00000000000..01c0d4c33e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsAndDefaultValues.fir.kt
@@ -0,0 +1,27 @@
+fun foo(a : Int = 1, b : String = "abc") {
+}
+
+fun bar(x : Int = 1, y : Int = 1, z : String) {
+}
+
+fun test() {
+    foo()
+    foo(2)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>("")
+    foo(b = "")
+    foo(1, "")
+    foo(a = 2)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, "", "")
+
+    bar(z = "")
+    <!INAPPLICABLE_CANDIDATE!>bar<!>()
+    <!INAPPLICABLE_CANDIDATE!>bar<!>("")
+    bar(1, 1, "")
+    bar(1, 1, "")
+    bar(1, z = "")
+    bar(1, z = "", y = 2)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(z = "", 1)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(1, zz = "",
+           <!UNRESOLVED_REFERENCE!>zz<!>.<!UNRESOLVED_REFERENCE!>foo<!>
+           )
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsInOverloads.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsInOverloads.fir.kt
new file mode 100644
index 00000000000..ce61b4cfa3c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsInOverloads.fir.kt
@@ -0,0 +1,14 @@
+interface A {
+    fun foo(a1: Int, a2: Double)
+}
+
+interface B {
+    fun foo(b1: Int, b2: String)
+}
+
+interface C : A, B {}
+
+fun test(d: C) {
+    d.foo(a1 = 1, a2 = 1.0)
+    d.foo(b1 = 1, b2 = "")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsInOverrides.fir.kt b/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsInOverrides.fir.kt
new file mode 100644
index 00000000000..8b8e9d729d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/namedArguments/namedArgumentsInOverrides.fir.kt
@@ -0,0 +1,22 @@
+interface A {
+    fun foo(a1: Int, a2: Double)
+}
+
+interface B {
+    fun foo(b1: Int, b2: Double)
+}
+
+interface C : A, B { // Warning here, this is correct, C.foo has no named parameters
+}
+
+interface D : C {
+    override fun foo(d1: Int, d2: Double)
+}
+
+fun test1(d: D) {
+    d.foo(d1 = 1, d2 = 1.0)
+}
+
+fun test2(c: C) {
+    c.<!INAPPLICABLE_CANDIDATE!>foo<!>(b1 = 1, b2 = 1.0)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/AssertNotNull.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/AssertNotNull.fir.kt
new file mode 100644
index 00000000000..c86e322fbab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/AssertNotNull.fir.kt
@@ -0,0 +1,39 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+fun main() {
+    val a : Int? = null
+    val b : Int? = null
+    checkSubtype<Int>(a!!)
+    a!! + 2
+    a!!.plus(2)
+    a!!.plus(b!!)
+    2.plus(b!!)
+    2 + b!!
+
+    val c = 1
+    c!!
+
+    val d : Any? = null
+
+    if (d != null) {
+        d!!
+    }
+
+    // smart cast isn't needed, but is reported due to KT-4294
+    if (d is String) {
+        d!!
+    }
+
+    if (d is String?) {
+        if (d != null) {
+            d!!
+        }
+        if (d is String) {
+            d!!
+        }
+    }
+
+    val f : String = a!!
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><String>(a!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/InfixCallNullability.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/InfixCallNullability.fir.kt
new file mode 100644
index 00000000000..feb0e66f806
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/InfixCallNullability.fir.kt
@@ -0,0 +1,41 @@
+// !WITH_NEW_INFERENCE
+class A() {
+    <!INAPPLICABLE_INFIX_MODIFIER!>operator infix fun plus(i : Int) {}<!>
+    operator fun unaryMinus() {}
+    <!INAPPLICABLE_INFIX_MODIFIER!>operator infix fun contains(a : Any?) : Boolean = true<!>
+}
+
+operator infix fun A.div(i : Int) {}
+operator infix fun A?.times(i : Int) {}
+
+fun test(x : Int?, a : A?) {
+    x.<!INAPPLICABLE_CANDIDATE!>plus<!>(1)
+    x?.plus(1)
+    x <!INAPPLICABLE_CANDIDATE!>+<!> 1
+    <!INAPPLICABLE_CANDIDATE!>-<!>x
+    x.<!INAPPLICABLE_CANDIDATE!>unaryMinus<!>()
+    x?.unaryMinus()
+
+    a.<!INAPPLICABLE_CANDIDATE!>plus<!>(1)
+    a?.plus(1)
+    a <!INAPPLICABLE_CANDIDATE!>plus<!> 1
+    a <!INAPPLICABLE_CANDIDATE!>+<!> 1
+    <!INAPPLICABLE_CANDIDATE!>-<!>a
+    a.<!INAPPLICABLE_CANDIDATE!>unaryMinus<!>()
+    a?.unaryMinus()
+
+    a.<!INAPPLICABLE_CANDIDATE!>div<!>(1)
+    a <!INAPPLICABLE_CANDIDATE!>/<!> 1
+    a <!INAPPLICABLE_CANDIDATE!>div<!> 1
+    a?.div(1)
+
+    a.times(1)
+    a * 1
+    a times 1
+    a?.times(1)
+
+    1 <!INAPPLICABLE_CANDIDATE!>in<!> a
+    a <!INAPPLICABLE_CANDIDATE!>contains<!> 1
+    a.<!INAPPLICABLE_CANDIDATE!>contains<!>(1)
+    a?.contains(1)
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/NullableNothingIsExactlyNull.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/NullableNothingIsExactlyNull.fir.kt
new file mode 100644
index 00000000000..6b400c9e105
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/NullableNothingIsExactlyNull.fir.kt
@@ -0,0 +1,8 @@
+fun test() {
+  val out : Int? = null
+  val x : Nothing? = null
+  if (out != x)
+    out.<!INAPPLICABLE_CANDIDATE!>plus<!>(1)
+  if (out == x) return
+  out.<!INAPPLICABLE_CANDIDATE!>plus<!>(1)
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/PreferExtensionsOnNullableReceiver.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/PreferExtensionsOnNullableReceiver.fir.kt
new file mode 100644
index 00000000000..b841960b590
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/PreferExtensionsOnNullableReceiver.fir.kt
@@ -0,0 +1,9 @@
+class Foo {
+    fun foo() {}
+}
+
+fun Any?.foo() {}
+
+fun test(f : Foo?) {
+  f.foo()
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/QualifiedExpressionNullability.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/QualifiedExpressionNullability.fir.kt
new file mode 100644
index 00000000000..0444e2a1c20
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/QualifiedExpressionNullability.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+class Foo {
+    fun foo(a: Foo): Foo = a
+}
+
+fun main() {
+    val x: Foo? = null
+    val y: Foo? = null
+    
+    x.<!INAPPLICABLE_CANDIDATE!>foo<!>(y)
+    x!!.foo(y)
+    x.foo(y!!)
+    x!!.foo(y!!)
+    
+    val a: Foo? = null
+    val b: Foo? = null
+    val c: Foo? = null
+    
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>(b.<!INAPPLICABLE_CANDIDATE!>foo<!>(c))
+    a!!.foo(b.<!INAPPLICABLE_CANDIDATE!>foo<!>(c))
+    a.foo(b!!.foo(c))
+    a!!.foo(b!!.foo(c))
+    a.foo(b.foo(c!!))
+    a!!.foo(b.foo(c!!))
+    a.foo(b!!.foo(c!!))
+    a!!.foo(b!!.foo(c!!))
+    
+    val z: Foo? = null
+    z!!.foo(z!!)
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/ReceiverNullability.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/ReceiverNullability.fir.kt
new file mode 100644
index 00000000000..803bcad34ce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/ReceiverNullability.fir.kt
@@ -0,0 +1,44 @@
+class A {
+    fun foo() {}
+}
+
+fun A.bar() {}
+fun A?.buzz() {}
+
+fun test(a : A?) {
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>() // error
+    a.<!INAPPLICABLE_CANDIDATE!>bar<!>() // error
+    a.buzz()
+
+    a?.foo()
+    a?.bar()
+    a?.buzz()
+}
+
+fun A.test2() {
+    foo()
+    bar()
+    buzz()
+
+    this.foo()
+    this.bar()
+    this.buzz()
+
+    this?.foo() // warning
+    this?.bar() // warning
+    this?.buzz() // warning
+}
+
+fun A?.test3() {
+    foo() // error
+    <!INAPPLICABLE_CANDIDATE!>bar<!>() // error
+    buzz()
+
+    this.<!INAPPLICABLE_CANDIDATE!>foo<!>() // error
+    this.<!INAPPLICABLE_CANDIDATE!>bar<!>() // error
+    this.buzz()
+
+    this?.foo()
+    this?.bar()
+    this?.buzz()
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/SenselessNullInWhen.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/SenselessNullInWhen.fir.kt
new file mode 100644
index 00000000000..665a439ed25
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/SenselessNullInWhen.fir.kt
@@ -0,0 +1,10 @@
+//KT-2457 Verify error when comparing not null value with null in when
+
+package kt2457
+
+fun foo(i: Int) : Int =
+    when (i) {
+        1 -> 1
+        null -> 1
+        else -> 1
+    }
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/dataFlowInfoAfterExclExcl.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/dataFlowInfoAfterExclExcl.fir.kt
new file mode 100644
index 00000000000..c533df109b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/dataFlowInfoAfterExclExcl.fir.kt
@@ -0,0 +1,8 @@
+fun foo(d: Any?) {
+    if (d is String?) {
+        d!!
+        doString(d)
+    }
+}
+
+fun doString(s: String) = s
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/equalityUnderNotNullCheck.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/equalityUnderNotNullCheck.fir.kt
new file mode 100644
index 00000000000..47dc3d1626c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/equalityUnderNotNullCheck.fir.kt
@@ -0,0 +1,5 @@
+fun test(a: Any?) {
+    if (a is String) {
+        a == ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/funcLiteralArgsInsideAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/funcLiteralArgsInsideAmbiguity.fir.kt
new file mode 100644
index 00000000000..c1cedf45194
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/funcLiteralArgsInsideAmbiguity.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+package d
+
+fun bar() {
+    val i: Int? = 42
+    if (i != null) {
+        <!AMBIGUITY!>doSmth1<!> {
+        val x = i + 1
+    }
+}
+}
+
+fun doSmth1(f: ()->Unit) {}
+fun doSmth1(g: (Int)->Unit) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/funcLiteralArgsInsideUnresolvedFunction.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/funcLiteralArgsInsideUnresolvedFunction.fir.kt
new file mode 100644
index 00000000000..a98b1329340
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/funcLiteralArgsInsideUnresolvedFunction.fir.kt
@@ -0,0 +1,10 @@
+package a
+
+fun foo() {
+    val i : Int? = 42
+    if (i != null) {
+        <!UNRESOLVED_REFERENCE!>doSmth<!> {
+            val x = i + 1
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1270.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1270.fir.kt
new file mode 100644
index 00000000000..da7a0604f37
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1270.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+//KT-1270 Poor highlighting when trying to dereference a nullable reference
+
+package kt1270
+
+fun foo() {
+    val sc = <!UNRESOLVED_REFERENCE!>java.util.<!UNRESOLVED_REFERENCE!>HashMap<!><String, SomeClass>()[""]<!>
+    val value = sc.<!UNRESOLVED_REFERENCE!>value<!>
+}
+
+private class SomeClass() {
+    val value : Int = 5
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1680.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1680.fir.kt
new file mode 100644
index 00000000000..85967016431
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1680.fir.kt
@@ -0,0 +1,14 @@
+//KT-1680 Warn if non-null variable is compared to null
+package kt1680
+
+fun foo() {
+    val x = 1
+    if (x != null) {} // <-- need a warning here!
+    if (x == null) {}
+    if (null != x) {}
+    if (null == x) {}
+
+    val y : Int? = 1
+    if (y != null) {}
+    if (y == null) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt
new file mode 100644
index 00000000000..1530d65eb5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+//KT-1778 Automatically cast error
+package kt1778
+
+fun main(args : Array<String>) {
+    val x = checkSubtype<Any>(args[0])
+    if(x is java.lang.CharSequence) {
+        if ("a" == x) x.<!UNRESOLVED_REFERENCE!>length<!> else x.length() // OK
+        if ("a" == x || "b" == x) x.<!UNRESOLVED_REFERENCE!>length<!> else x.length() // <– THEN ERROR
+        if ("a" == x && "a" == x) x.<!UNRESOLVED_REFERENCE!>length<!> else x.length() // <– ELSE ERROR
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2109.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2109.fir.kt
new file mode 100644
index 00000000000..e8677780cce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2109.fir.kt
@@ -0,0 +1,20 @@
+//KT-2109 Nullability inference fails in extension function
+package kt2109
+
+class A {
+    fun foo() {}
+}
+
+fun A?.bar() {
+    if (this == null) {
+        return
+    }
+    foo()
+}
+
+fun A.baz() {
+    if (this == null) {
+        return
+    }
+    foo()
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2125.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2125.fir.kt
new file mode 100644
index 00000000000..b50cddfcd3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2125.fir.kt
@@ -0,0 +1,12 @@
+//KT-2125 Inconsistent error message on UNSAFE_CALL
+
+package e
+
+fun main() {
+    val compareTo = 1
+    val s: String? = null
+    s.<!INAPPLICABLE_CANDIDATE!>compareTo<!>("")
+
+    val bar = 2
+    s.<!UNRESOLVED_REFERENCE!>bar<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2146.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2146.fir.kt
new file mode 100644
index 00000000000..89a349c22ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2146.fir.kt
@@ -0,0 +1,55 @@
+// !WITH_NEW_INFERENCE
+//KT-2146 Nullability casts in when.
+package kt2146
+
+fun f1(s: Int?): Int {
+    return when (s) {
+        null -> 3
+        else -> s
+    }
+}
+
+fun f2(s: Int?): Int {
+    return when (s) {
+        !is Int -> s
+        else -> s
+    }
+}
+
+fun f3(s: Int?): Int {
+    return when (s) {
+        is Int -> s
+        else -> s
+    }
+}
+
+fun f4(s: Int?): Int {
+    return when {
+        s == 4 -> s
+        s == null -> s
+        else -> s
+    }
+}
+
+fun f5(s: Int?): Int {
+    return when (s) {
+        s -> s
+        s!! -> s
+        s -> s
+        else -> 0
+    }
+}
+
+fun f6(s: Int?): Int {
+    return when {
+        s is Int -> s
+        else -> s
+    }
+}
+
+fun f7(s: Int?): Int {
+    return when {
+        s !is Int -> s
+        else -> s
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2164.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2164.fir.kt
new file mode 100644
index 00000000000..b11da4a5726
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2164.fir.kt
@@ -0,0 +1,39 @@
+// !WITH_NEW_INFERENCE
+//KT-2164 !! does not propagate nullability information
+package kt2164
+
+fun foo(x: Int): Int = x + 1
+
+fun main() {
+    val x: Int? = null
+
+    foo(x)
+
+    if (x != null) {
+        foo(x)
+        foo(x!!)
+        foo(x)
+    }
+
+    foo(x)
+
+    if (x != null) {
+        foo(x)
+        foo(x!!)
+        foo(x)
+    } else {
+        foo(x)
+        foo(x!!)
+        foo(x)
+    }
+
+    foo(x)
+    foo(x!!)
+    foo(x)
+    
+    val y: Int? = null
+    y!!
+    y!!
+    foo(y)
+    foo(y!!)
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2176.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2176.fir.kt
new file mode 100644
index 00000000000..67c08638cce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2176.fir.kt
@@ -0,0 +1,29 @@
+// !CHECK_TYPE
+
+//KT-2176 non-nullability is not inferred after !! or "as"
+package kt2176
+
+fun f1(a: String?) {
+    a!!
+    checkSubtype<String>(a)
+}
+
+fun f2(a: String) {
+    a!!
+    checkSubtype<String>(a)
+}
+
+fun f3(a: Any?) {
+    a as String
+    checkSubtype<String>(a)
+}
+
+fun f4(a: Any) {
+    a as String
+    checkSubtype<String>(a)
+}
+
+fun f5(a: String) {
+    a as Any?
+    checkSubtype<String>(a)
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2195.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2195.fir.kt
new file mode 100644
index 00000000000..673e4ea7220
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2195.fir.kt
@@ -0,0 +1,8 @@
+//KT-2195 error "Only safe calls are allowed ..." but it is function param (val)
+package foo
+
+private fun <T> sendCommand(errorCallback: (()->Unit)? = null) {
+    if (errorCallback != null) {
+        errorCallback()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2212.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2212.fir.kt
new file mode 100644
index 00000000000..5e549d859dd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2212.fir.kt
@@ -0,0 +1,8 @@
+//KT-2212 Incomplete nullability information
+package kt2212
+
+fun main() {
+    val x: Int? = 1
+    if (x == null) return
+    System.out.println(x.plus(x!!))
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2216.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2216.fir.kt
new file mode 100644
index 00000000000..efc455e8dc3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2216.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -DEBUG_INFO_SMARTCAST
+//KT-2216 Nullability of a value determined in function parameter computation doesn't pass to code following
+package kt2216
+
+fun bar(y: Int, z: Int) = y + z
+fun baz(a: Int, b: Int, c: Int, d: Int) = a + b + c + d
+
+fun foo() {
+    val x: Int? = 0
+
+    bar(if (x != null) x else return, x)
+    x + 2
+    bar(x, x!!)
+
+    val y: Int? = 0
+    val z: Int? = 0
+    bar(if (y != null) y else z, y)
+    y <!INAPPLICABLE_CANDIDATE!>+<!> 2
+    baz(y, y, if (y == null) return else y, y)
+    baz(y, z!!, z, y)
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2223.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2223.fir.kt
new file mode 100644
index 00000000000..2817ee45012
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2223.fir.kt
@@ -0,0 +1,8 @@
+//KT-2223 Comparing non-null value with null might produce helpful warning
+package kt2223
+
+fun foo() {
+    val x: Int? = null
+    if (x == null) return
+    if (x == null) return
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2234.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2234.fir.kt
new file mode 100644
index 00000000000..f79097f30b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2234.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+package a
+
+//KT-2234 'period!!' has type Int?
+
+class Pair<A, B>(val a: A, val b: B)
+
+fun main() {
+    val d : Long = 1
+    val period : Int? = null
+    if (period != null) Pair(d, checkSubtype<Int>(period!!)) else Pair(d, 1)
+    if (period != null) Pair(d, checkSubtype<Int>(period)) else Pair(d, 1)
+}
+
+fun foo() {
+    val x : Int? = 3
+    if (x != null)  {
+        val u = checkSubtype<Int>(x!!)
+        val y = checkSubtype<Int>(x)
+        val z : Int = y
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2336.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2336.fir.kt
new file mode 100644
index 00000000000..aaf1a9743cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2336.fir.kt
@@ -0,0 +1,11 @@
+fun main() {
+    val b: Boolean? = null
+    if (b != null) {
+        if (!b) {} // OK
+        if (b) {} // Error: Condition must be of type kotlin.Boolean, but is of type kotlin.Boolean?
+        if (b!!) {} // WARN: Unnecessary non-null assertion (!!) on a non-null receiver of type kotlin.Boolean?
+        foo(b) // OK
+    }
+}
+
+fun foo(a: Boolean) = a
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt244.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt244.fir.kt
new file mode 100644
index 00000000000..85372301de9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt244.fir.kt
@@ -0,0 +1,33 @@
+package kt244
+
+
+// KT-244 Use dataflow info while resolving variable initializers
+
+fun f(s: String?) {
+    if (s != null) {
+        s.length  //ok
+        var i = s.length //error: Only safe calls are allowed on a nullable receiver
+        System.out.println(s.length) //error
+    }
+}
+
+// more tests
+class A(a: String?) {
+    val b = if (a != null) a.length else 1
+    init {
+        if (a != null) {
+            val c = a.length
+        }
+    }
+
+    val i : Int
+
+    init {
+        if (a is String) {
+            i = a.length
+        }
+        else {
+            i = 3
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt30734.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt30734.fir.kt
new file mode 100644
index 00000000000..25ea6b526a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt30734.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +NewInference
+// Issue: KT-30734
+
+class Sample {
+    fun foo(): Boolean = true
+}
+
+fun test(ls: Sample?) {
+    val filter: () -> Boolean = if (ls == null) {
+        { false }
+    } else {
+        { ls.foo() } // OK in OI, error in NI
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt362.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt362.fir.kt
new file mode 100644
index 00000000000..301ae2f36b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt362.fir.kt
@@ -0,0 +1,29 @@
+// FILE: this.kt
+
+// KT-362 Don't allow.smartcasts on vals that are not internal
+package example
+
+fun test() {
+  val p = test.Public()
+  if (p.public is Int) p.public + 1
+  if (p.<!INAPPLICABLE_CANDIDATE!>protected<!> is Int) p.<!INAPPLICABLE_CANDIDATE!>protected<!> + 1
+  if (p.internal is Int) p.internal + 1
+  val i = test.Internal()
+  if (i.public is Int) i.public + 1
+  if (i.<!INAPPLICABLE_CANDIDATE!>protected<!> is Int) i.<!INAPPLICABLE_CANDIDATE!>protected<!> + 1
+  if (i.internal is Int) i.internal + 1
+}
+
+// FILE: other.kt
+package test
+
+public class Public() {
+    public val public : Int? = 1;
+    protected val protected : Int? = 1;
+    val internal : Int? = 1
+}
+internal class Internal() {
+    public val public : Int? = 1;
+    protected val protected : Int? = 1;
+    val internal : Int? = 1
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/noSenselessNullOnNullableType.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/noSenselessNullOnNullableType.fir.kt
new file mode 100644
index 00000000000..b0624fd098e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/noSenselessNullOnNullableType.fir.kt
@@ -0,0 +1,21 @@
+// FILE: A.java
+
+class A {
+    enum Empty {}
+
+    static Empty foo() { return null; }
+}
+
+// FILE: 1.kt
+
+fun bar() = when (A.foo()) {
+    null -> "null"
+    else -> "else"
+}
+
+fun <T : Number?> baz(t: T) = when (t) {
+    is Int -> "int"
+    is Long -> "long"
+    null -> "null"
+    else -> "else"
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/noUnnecessaryNotNullAssertionOnErrorType.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/noUnnecessaryNotNullAssertionOnErrorType.fir.kt
new file mode 100644
index 00000000000..ff08f2d31c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/noUnnecessaryNotNullAssertionOnErrorType.fir.kt
@@ -0,0 +1,7 @@
+package a
+
+fun foo() {
+    bar()!!
+}
+
+fun bar() = <!UNRESOLVED_REFERENCE!>aa<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/notnullTypesFromJavaWithSmartcast.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/notnullTypesFromJavaWithSmartcast.fir.kt
new file mode 100644
index 00000000000..cc63bf707ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/notnullTypesFromJavaWithSmartcast.fir.kt
@@ -0,0 +1,20 @@
+// FILE: JClass.java
+
+import org.jetbrains.annotations.NotNull;
+
+public class JClass {
+    @NotNull
+    public static <T> T getNotNullT() {
+        return null;
+    }
+}
+
+// FILE: test.kt
+fun <T : Any> test() {
+    var value: T? = null
+    if (value == null) {
+        value = JClass.getNotNullT()
+    }
+
+    value.<!INAPPLICABLE_CANDIDATE!>hashCode<!>() // unsafe call error
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/nullableReceiverWithOverloadedMethod.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/nullableReceiverWithOverloadedMethod.fir.kt
new file mode 100644
index 00000000000..722a7a5af42
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/nullableReceiverWithOverloadedMethod.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A {
+    fun f(x: Boolean): Int = 0
+
+    fun f(y: String): Int = 0
+}
+
+class B {
+    private var a: A? = null
+
+    fun takeInt(i: Int) {}
+
+    fun f() {
+        a = A()
+        a.f(true)
+        takeInt(a.f(""))
+        a.<!INAPPLICABLE_CANDIDATE!>f<!>()
+    }
+
+    fun g() {
+        takeInt(if (3 > 2) {
+            a = A()
+            a.f(true)
+        } else {
+            6
+        })
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/senslessComparisonWithNullOnTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/senslessComparisonWithNullOnTypeParameters.fir.kt
new file mode 100644
index 00000000000..2f1d0404768
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/senslessComparisonWithNullOnTypeParameters.fir.kt
@@ -0,0 +1,16 @@
+// The type checker used to think that T is not null no matter what the upper bound
+
+fun <T, INDIRECT: T> nullableUpperBound(t: T, ind: INDIRECT) {
+    if (t == null) {} // was a warning
+    if (t != null) {}  // was a warning
+    if (ind == null) {}  // was a warning
+    if (ind != null) {}  // was a warning
+}
+
+fun <T: Any, INDIRECT: T> notNullUpperBound(t: T, ind: INDIRECT) {
+    if (t == null) {} // still a warning
+    if (t != null) {} // still a warning
+    if (ind == null) {} // still a warning
+    if (ind != null) {} // still a warning
+}
+
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/smartCastReceiverWithGenerics.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/smartCastReceiverWithGenerics.fir.kt
new file mode 100644
index 00000000000..d2df085942c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/smartCastReceiverWithGenerics.fir.kt
@@ -0,0 +1,7 @@
+fun test(a: Any?) {
+    if (a != null) {
+        a.foo(11)
+    }
+}
+
+fun <T> Any.foo(t: T) = t
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/smartCastsAndBooleanExpressions.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/smartCastsAndBooleanExpressions.fir.kt
new file mode 100644
index 00000000000..ad109901e41
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/smartCastsAndBooleanExpressions.fir.kt
@@ -0,0 +1,8 @@
+fun foo(b: Boolean?, c: Boolean) {
+    if (b != null && b) {}
+    if (b == null || b) {}
+    if (b != null) {
+        if (b && c) {}
+        if (b || c) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unnecessaryNotNullAssertion.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unnecessaryNotNullAssertion.fir.kt
new file mode 100644
index 00000000000..a99f24208ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unnecessaryNotNullAssertion.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -SENSELESS_COMPARISON, -DEBUG_INFO_SMARTCAST
+
+fun takeNotNull(s: String) {}
+fun <T> notNull(): T = TODO()
+fun <T> nullable(): T? = null
+fun <T> dependOn(x: T) = x
+
+fun test() {
+    takeNotNull(notNull()!!)
+    takeNotNull(nullable()!!)
+
+    var x: String? = null
+    takeNotNull(dependOn(x)!!)
+    takeNotNull(dependOn(dependOn(x))!!)
+    takeNotNull(dependOn(dependOn(x)!!))
+    takeNotNull(dependOn(dependOn(x!!)))
+
+    if (x != null) {
+        takeNotNull(dependOn(x)!!)
+        takeNotNull(dependOn(dependOn(x))!!)
+        takeNotNull(dependOn(dependOn(x)!!))
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unstableSmartcastWhenOpenGetterWithOverloading.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unstableSmartcastWhenOpenGetterWithOverloading.fir.kt
new file mode 100644
index 00000000000..92eb68bb5a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unstableSmartcastWhenOpenGetterWithOverloading.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Ctx
+class CtxImpl : Ctx {
+    fun doJob(a: Int) {}
+    fun doJob(s: String) {}
+}
+
+open class Test(open val ctx: Ctx) {
+    fun test() {
+        when (ctx) {
+            is CtxImpl -> ctx.doJob(2)
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unstableSmartcastWithOverloadedExtensions.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unstableSmartcastWithOverloadedExtensions.fir.kt
new file mode 100644
index 00000000000..f3b15e045ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/unstableSmartcastWithOverloadedExtensions.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A
+class B
+
+fun A.foo(a: A) {}
+fun A.foo(b: B) {}
+var a: A? = null
+
+fun smartCastInterference(b: B) {
+    if (a != null) {
+        a.foo(b)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/baseWithNullableUpperBound.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/baseWithNullableUpperBound.fir.kt
new file mode 100644
index 00000000000..1ae495cde52
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/baseWithNullableUpperBound.fir.kt
@@ -0,0 +1,13 @@
+fun <NN: Any, NNN: NN> nonMisleadingNullable(
+        nn: NN?,
+        nnn: NNN?
+) {}
+
+fun <T, N: T, INDIRECT: N> misleadingNullableSimple(
+        t: T?,
+        t2: T?,
+        n: N?,
+        ind: INDIRECT?
+) {}
+
+fun <T> interactionWithRedundant(t: T??) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/elvisOnUnit.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/elvisOnUnit.fir.kt
new file mode 100644
index 00000000000..87606001595
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/elvisOnUnit.fir.kt
@@ -0,0 +1,11 @@
+class My {
+    fun other() {}
+}
+
+fun another() {}
+
+fun foo(x: My?) {
+    // Both elvis parts should be alive
+    // See also KT-7936, KT-8347
+    x?.other() ?: another()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/nullAssertOnTypeWithNullableUpperBound.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/nullAssertOnTypeWithNullableUpperBound.fir.kt
new file mode 100644
index 00000000000..c687da5c046
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/nullAssertOnTypeWithNullableUpperBound.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+fun <T> test(t: T): T {
+    if (t != null) {
+        return t!!
+    }
+    return t!!
+}
+
+fun <T> T.testThis(): String {
+    if (this != null) {
+        return this!!.toString()
+    }
+    return this!!.toString()
+}
+
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentForIn.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentForIn.fir.kt
new file mode 100644
index 00000000000..8adfaa1fcd8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentForIn.fir.kt
@@ -0,0 +1,3 @@
+fun test(x: Int?) {
+     x in 1..2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentToNonNullParameterPlatform.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentToNonNullParameterPlatform.fir.kt
new file mode 100644
index 00000000000..2ef99b24447
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentToNonNullParameterPlatform.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    void foo(String x) {}
+    void foo(@NotNull Double x) {}
+    void foo(@Nullable Byte x) {}
+}
+
+// FILE: test.kt
+
+fun test(j: J, nullStr: String?, nullByte: Byte?, nullDouble: Double?) {
+    j.foo(nullStr)
+    j.foo(nullDouble)
+    j.foo(nullByte)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentToNonNullParameterSimple.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentToNonNullParameterSimple.fir.kt
new file mode 100644
index 00000000000..af6e1aea464
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/nullableArgumentToNonNullParameterSimple.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(x: String) {}
+fun foo(x: Int) {}
+fun foo(x: Int, y: String) {}
+
+fun bar(nullX: Int?, nullY: String?, notNullY: String) {
+    foo(nullX)
+    foo(nullX, notNullY)
+    foo(nullX, nullY)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/redundantNullable.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullable.fir.kt
new file mode 100644
index 00000000000..509d372da7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullable.fir.kt
@@ -0,0 +1,9 @@
+class Generic<T>
+
+fun redundantNullable(
+        i: Int??,
+        three: Int???,
+        gOut: Generic<Int>??,
+        gIn: Generic<Int??>
+) {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/redundantNullableInSupertype.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullableInSupertype.fir.kt
new file mode 100644
index 00000000000..6924c396747
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullableInSupertype.fir.kt
@@ -0,0 +1,9 @@
+interface A
+interface X: A?? {
+
+}
+
+fun <T> interaction(t: T) {
+    if (t == null) {}
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/safeAccessOnUnit.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/safeAccessOnUnit.fir.kt
new file mode 100644
index 00000000000..e9904a7da75
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/safeAccessOnUnit.fir.kt
@@ -0,0 +1,7 @@
+data class My(val x: Unit)
+
+fun foo(my: My?): Int? {
+    val x = my?.x
+    // ?. is required here
+    return x?.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/safeCallOnTypeWithNullableUpperBound.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/safeCallOnTypeWithNullableUpperBound.fir.kt
new file mode 100644
index 00000000000..4cedf9fc624
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/safeCallOnTypeWithNullableUpperBound.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+fun <T> test(t: T): String? {
+    if (t != null) {
+        return t?.toString()
+    }
+    return t?.toString()
+}
+
+fun <T> T.testThis(): String? {
+    if (this != null) {
+        return this?.toString()
+    }
+    return this?.toString()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/safeCallWithInvoke.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/safeCallWithInvoke.fir.kt
new file mode 100644
index 00000000000..feb936e7966
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/safeCallWithInvoke.fir.kt
@@ -0,0 +1,12 @@
+class A {
+    val b = B()
+}
+class B
+operator fun B.invoke(i: Int) = i
+
+fun foo(i: Int) = i
+
+fun test(a: A?) {
+    a?.b(1) //should be no warning
+    foo(a?.b(1)) //no warning, only error
+}
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/uselessElvis.fir.kt b/compiler/testData/diagnostics/tests/nullableTypes/uselessElvis.fir.kt
new file mode 100644
index 00000000000..6a169949d59
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/nullableTypes/uselessElvis.fir.kt
@@ -0,0 +1,48 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -SENSELESS_COMPARISON, -DEBUG_INFO_SMARTCAST
+
+fun <T: Any?> test1(t: Any?): Any {
+    return t as T ?: ""
+}
+
+fun <T: Any> test2(t: Any?): Any {
+    return t as T ?: ""
+}
+
+fun <T: Any?> test3(t: Any?): Any {
+    if (t != null) {
+        return t ?: ""
+    }
+
+    return 1
+}
+
+fun takeNotNull(s: String) {}
+fun <T> notNull(): T = TODO()
+fun <T> nullable(): T? = null
+fun <T> dependOn(x: T) = x
+
+fun test() {
+    takeNotNull(notNull() ?: "")
+    takeNotNull(nullable() ?: "")
+
+    val x: String? = null
+    takeNotNull(dependOn(x) ?: "")
+    takeNotNull(dependOn(dependOn(x)) ?: "")
+    takeNotNull(dependOn(dependOn(x as String)) ?: "")
+
+    if (x != null) {
+        takeNotNull(dependOn(x) ?: "")
+        takeNotNull(dependOn(dependOn(x)) ?: "")
+        takeNotNull(dependOn(dependOn(x) as? String) ?: "")
+    }
+
+    takeNotNull(bar()!!)
+}
+
+inline fun <reified T : Any> reifiedNull(): T? = null
+
+fun testFrom13648() {
+    <!INAPPLICABLE_CANDIDATE!>takeNotNull<!>(reifiedNull() ?: "")
+}
+
+fun bar() = <!UNRESOLVED_REFERENCE!>unresolved<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/numbers/characterIsNotANumber.fir.kt b/compiler/testData/diagnostics/tests/numbers/characterIsNotANumber.fir.kt
new file mode 100644
index 00000000000..6e89529d5b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/numbers/characterIsNotANumber.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+fun foo(n: Number) = n
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>('a')
+    
+    val c = 'c'
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(c)
+
+    val d: Char? = 'd'
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(d!!)
+}
diff --git a/compiler/testData/diagnostics/tests/numbers/doublesInSimpleConstraints.fir.kt b/compiler/testData/diagnostics/tests/numbers/doublesInSimpleConstraints.fir.kt
new file mode 100644
index 00000000000..31ef50e4c41
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/numbers/doublesInSimpleConstraints.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+package a
+
+fun <T> id(t: T): T = t
+
+fun <T> either(t1: T, t2: T): T = t1
+
+fun test() {
+    val a: Float = id(2.0.toFloat())
+
+    val b = id(2.0)
+    checkSubtype<Double>(b)
+
+    val c = either<Number>(1, 2.3)
+    checkSubtype<Number>(c)
+
+    val d = either(11, 2.3)
+    checkSubtype<Any>(d)
+
+    val e: Float = id(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/numbers/intValuesOutOfRange.fir.kt b/compiler/testData/diagnostics/tests/numbers/intValuesOutOfRange.fir.kt
new file mode 100644
index 00000000000..48e649a2cb5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/numbers/intValuesOutOfRange.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+package a
+
+fun foo(i: Int) = i
+
+fun bar(l: Long) = l
+
+fun main() {
+    val i = <!ILLEGAL_CONST_EXPRESSION, INFERENCE_ERROR, INFERENCE_ERROR!>111111111111111777777777777777<!>
+
+    //todo add diagnostic text messages
+    //report only 'The value is out of range'
+    //not 'An integer literal does not conform to the expected type Int/Long'
+    val l: Long = <!ILLEGAL_CONST_EXPRESSION, INFERENCE_ERROR!>1111111111111117777777777777777<!>
+    foo(<!ILLEGAL_CONST_EXPRESSION, INFERENCE_ERROR!>11111111111111177777777777777<!>)
+    bar(<!ILLEGAL_CONST_EXPRESSION, INFERENCE_ERROR!>11111111111111177777777777777<!>)
+}
diff --git a/compiler/testData/diagnostics/tests/numbers/numberAsUnionAndIntersection.fir.kt b/compiler/testData/diagnostics/tests/numbers/numberAsUnionAndIntersection.fir.kt
new file mode 100644
index 00000000000..4d9df23ad57
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/numbers/numberAsUnionAndIntersection.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test(numbers: List<Number>) {
+
+    // Short <: R, ILT <: R => CST(Short, ILT) = Short
+    // => we should pick Short in such situation as it more specific
+    shortExpected { getShort() ?: 1 }
+
+    // Short <: R, ILT <: R, R <: Comparable<R> =>
+    // Short <: Comparable<R>, ILT <: Comparable<R> =>
+    // Comparable<Short> <: Comparable<R>, Comparable<ILT> <: Comparable<R> =>
+    // R <: Short, R <: ILT =>
+    // R := Short, R := ILT
+    // => we should pick Short as it more specific
+    shortComparable { getShort() ?: 1 }
+}
+
+fun <R> shortExpected(f: () -> R) {}
+fun <R : Comparable<R>> shortComparable(f: () -> R) {}
+
+fun getShort(): Short? = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/numbers/numbersInSimpleConstraints.fir.kt b/compiler/testData/diagnostics/tests/numbers/numbersInSimpleConstraints.fir.kt
new file mode 100644
index 00000000000..4058881faf7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/numbers/numbersInSimpleConstraints.fir.kt
@@ -0,0 +1,78 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+package a
+
+fun <T> id(t: T): T = t
+
+fun <T> either(t1: T, t2: T): T = t1
+
+fun other(s: String) {}
+
+fun <T> otherGeneric(l: List<T>) {}
+
+fun test() {
+    val a: Byte = id(1)
+
+    val b: Byte = id(300)
+
+    val c: Int = id(9223372036854775807)
+
+    val d = id(22)
+    checkSubtype<Int>(d)
+
+    val e = id(9223372036854775807)
+    e checkType { <!UNRESOLVED_REFERENCE!>_<!><Long>() }
+
+    val f: Byte = either(1, 2)
+
+    val g: Byte = either(1, 300)
+
+    <!INAPPLICABLE_CANDIDATE!>other<!>(11)
+
+    <!INAPPLICABLE_CANDIDATE!>otherGeneric<!>(1)
+
+    val r = either(1, "")
+    r checkType { <!UNRESOLVED_REFERENCE!>_<!><Any>() }
+
+    use(a, b, c, d, e, f, g, r)
+}
+
+fun use(vararg a: Any?) = a
+
+interface Inv<T>
+
+fun <T> exactBound(t: T, l: Inv<T>): T = throw Exception("$t $l")
+
+fun testExactBound(invS: Inv<String>, invI: Inv<Int>, invB: Inv<Byte>) {
+    <!INAPPLICABLE_CANDIDATE!>exactBound<!>(1, invS)
+    exactBound(1, invI)
+
+    val b = exactBound(1, invB)
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><Byte>() }
+}
+
+interface Cov<out T>
+
+fun <T> lowerBound(t: T, l : Cov<T>): T = throw Exception("$t $l")
+
+fun testLowerBound(cov: Cov<String>, covN: Cov<Number>) {
+    val r = lowerBound(1, cov)
+    r checkType { <!UNRESOLVED_REFERENCE!>_<!><Any>() }
+
+    val n = lowerBound(1, covN)
+    n checkType { <!UNRESOLVED_REFERENCE!>_<!><Number>() }
+}
+
+interface Contr<in T>
+
+fun <T> upperBound(t: T, l: Contr<T>): T = throw Exception("$t $l")
+
+fun testUpperBound(contrS: Contr<String>, contrB: Contr<Byte>, contrN: Contr<Number>) {
+    <!INAPPLICABLE_CANDIDATE!>upperBound<!>(1, contrS)
+
+    val n = upperBound(1, contrN)
+    n checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    val b = upperBound(1, contrB)
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><Byte>() }
+}
diff --git a/compiler/testData/diagnostics/tests/objects/Objects.fir.kt b/compiler/testData/diagnostics/tests/objects/Objects.fir.kt
new file mode 100644
index 00000000000..c417e1904c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/Objects.fir.kt
@@ -0,0 +1,29 @@
+package toplevelObjectDeclarations
+
+  open class Foo(y : Int) {
+    open fun foo() : Int = 1
+  }
+
+  class T : Foo {}
+
+  object A : Foo {
+    val x : Int = 2
+
+    fun test() : Int {
+      return x + foo()
+    }
+  }
+
+  object B : A {}
+
+  val x = A.foo()
+
+  val y = object : Foo(x) {
+    init {
+      x + 12
+    }
+
+    override fun foo() : Int = 1
+  }
+
+  val z = y.foo()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/ObjectsInheritance.fir.kt b/compiler/testData/diagnostics/tests/objects/ObjectsInheritance.fir.kt
new file mode 100644
index 00000000000..06a40bef38f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/ObjectsInheritance.fir.kt
@@ -0,0 +1,5 @@
+package toplevelObjectDeclarations
+
+object CObj {}
+
+object DOjb : CObj {}
diff --git a/compiler/testData/diagnostics/tests/objects/ObjectsLocal.fir.kt b/compiler/testData/diagnostics/tests/objects/ObjectsLocal.fir.kt
new file mode 100644
index 00000000000..38cd5054c67
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/ObjectsLocal.fir.kt
@@ -0,0 +1,25 @@
+// NI_EXPECTED_FILE
+
+package localObjects
+
+object A {
+    val x : Int = 0
+}
+
+open class Foo {
+    fun foo() : Int = 1
+}
+
+fun test() {
+    A.x
+    val b = object : Foo() {
+    }
+    b.foo()
+
+    object B {
+        fun foo() {}
+    }
+    B.foo()
+}
+
+val bb = <!UNRESOLVED_REFERENCE!>B<!>.<!UNRESOLVED_REFERENCE!>foo<!>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/ObjectsNested.fir.kt b/compiler/testData/diagnostics/tests/objects/ObjectsNested.fir.kt
new file mode 100644
index 00000000000..faf7d4a6cd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/ObjectsNested.fir.kt
@@ -0,0 +1,29 @@
+package nestedObejcts
+
+object A {
+    val b = B
+    val d = A.B.A
+
+    object B {
+        val a = A
+        val e = B.A
+
+        object A {
+            val a = A
+            val b = B
+            val x = nestedObejcts.A.B.A
+            val y = this@A
+        }
+    }
+
+}
+object B {
+    val b = B
+    val c = A.B
+}
+
+val a = A
+val b = B
+val c = A.B
+val d = A.B.A
+val e = B.<!UNRESOLVED_REFERENCE!>A<!>.<!UNRESOLVED_REFERENCE!>B<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/OpenInObject.fir.kt b/compiler/testData/diagnostics/tests/objects/OpenInObject.fir.kt
new file mode 100644
index 00000000000..ca357cdd3c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/OpenInObject.fir.kt
@@ -0,0 +1,9 @@
+object Obj {
+    fun foo() {}
+
+    open fun bar() {}
+
+    var x: Int = 0
+
+    open var y: Int = 1
+}
diff --git a/compiler/testData/diagnostics/tests/objects/invokeOnInnerObject.fir.kt b/compiler/testData/diagnostics/tests/objects/invokeOnInnerObject.fir.kt
new file mode 100644
index 00000000000..6720e33f495
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/invokeOnInnerObject.fir.kt
@@ -0,0 +1,12 @@
+//no nested class access via instance reference error
+fun test() {
+    A.Companion.<!INAPPLICABLE_CANDIDATE!>f<!>("")
+}
+
+class A() {
+    companion object {
+        object f {
+            operator fun invoke(i: Int) = i
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/annotationConstructor.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/annotationConstructor.fir.kt
new file mode 100644
index 00000000000..52c9decb651
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/annotationConstructor.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+open class Base {
+    companion object {
+        annotation class Foo
+    }
+}
+
+class Derived : Base() {
+
+    @Foo
+    fun foo() = 42
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/callableReferenceComplexCasesWithImportsOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferenceComplexCasesWithImportsOld.fir.kt
new file mode 100644
index 00000000000..54d29f1c5d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferenceComplexCasesWithImportsOld.fir.kt
@@ -0,0 +1,74 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+import A.Base.Companion.FromABaseCompanion
+import B.Base.Companion.FromBBaseCompanion
+import C.Base.Companion.FromCBaseCompanion
+import D.Base.Companion.FromDBaseCompanion
+
+// ===== Case 1: LHS is a class
+//
+object A {
+    open class Base {
+        companion object {
+            class FromABaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromABaseCompanion::foo
+    }
+}
+
+// ===== Case 2: LHS is a class with companion object, function comes from class
+
+object B {
+    open class Base {
+        companion object {
+            class FromBBaseCompanion {
+                fun foo() = 42
+
+                companion object {}
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromBBaseCompanion::foo
+    }
+}
+
+// ==== Case 3: LHS is a class with companion object, function comes from companion
+
+object C {
+    open class Base {
+        companion object {
+            class FromCBaseCompanion {
+                companion object {
+                    fun foo() = 42
+                }
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromCBaseCompanion::foo
+    }
+}
+
+// ==== Case 4: LHS is an object
+
+object D {
+    open class Base {
+        companion object {
+            object FromDBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromDBaseCompanion::foo
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesComplexCasesWithQualificationOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesComplexCasesWithQualificationOld.fir.kt
new file mode 100644
index 00000000000..9f5fb426f29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesComplexCasesWithQualificationOld.fir.kt
@@ -0,0 +1,69 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+// ===== Case 1: LHS is a class
+//
+object A {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = A.Base.Companion.FromBaseCompanion::foo
+    }
+}
+
+// ===== Case 2: LHS is a class with companion object, function comes from class
+
+object B {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                fun foo() = 42
+
+                companion object {}
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = B.Base.Companion.FromBaseCompanion::foo
+    }
+}
+
+// ==== Case 3: LHS is a class with companion object, function comes from companion
+
+object C {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                companion object {
+                    fun foo() = 42
+                }
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = C.Base.Companion.FromBaseCompanion::foo
+    }
+}
+
+// ==== Case 4: LHS is an object
+
+object D {
+    open class Base {
+        companion object {
+            object FromBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = D.Base.Companion.FromBaseCompanion::foo
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesNew.fir.kt
new file mode 100644
index 00000000000..bdf54158467
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesNew.fir.kt
@@ -0,0 +1,142 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// See KT-21515 for a class diagram and details
+
+// class is to prevent accidental short-name import
+class O {
+    open class Alpha {
+        open fun foo() = 42
+
+        class FromAlpha {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionAlpha {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class Beta : Alpha() {
+        override fun foo() = 42
+
+        class FromBeta {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionBeta {
+                fun foo() = 42
+            }
+        }
+    }
+
+
+    open class A {
+        open fun foo() = 42
+
+        class FromA {
+            fun foo() = 42
+        }
+
+        companion object : Beta() {
+            class FromCompanionA {
+                fun foo() = 42
+            }
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open fun foo() = 42
+
+        class FromFarAway {
+            fun foo() = 42
+        }
+
+    }
+
+    open class Gamma {
+        open fun foo() = 42
+
+        class FromGamma {
+            fun foo() = 42
+        }
+
+        companion object : FarAway() {
+            class FromCompanionGamma {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class B : A() {
+        override fun foo() = 42
+
+        class FromB {
+            fun foo() = 42
+        }
+
+        companion object : Gamma() {
+            override fun foo() = 42
+
+            class FromCompanionB {
+                fun foo() = 42
+            }
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open fun foo() = 42
+    class FromDelta {
+        fun foo() = 42
+    }
+}
+
+class C : O.B() {
+    override fun foo() = 42
+
+    companion object : Delta() {
+        class FromCompanionC {
+            fun foo() = 42
+        }
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = FromA::foo
+    val d = FromB::foo
+
+    // VISIBLE: Classifiers from our own companion
+    val n = FromCompanionC::foo
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = <!UNRESOLVED_REFERENCE!>A<!>::foo
+    val b = <!UNRESOLVED_REFERENCE!>A<!>::foo
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = FromCompanionA::foo
+    val f = FromCompanionB::foo
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = <!UNRESOLVED_REFERENCE!>Alpha<!>::foo
+    val h = <!UNRESOLVED_REFERENCE!>Beta<!>::foo
+    val i = <!UNRESOLVED_REFERENCE!>Gamma<!>::foo
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = FromAlpha::foo
+    val l = FromBeta::foo
+    val m = FromGamma::foo
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = <!UNRESOLVED_REFERENCE!>FromCompanionAlpha<!>::foo
+    val p = <!UNRESOLVED_REFERENCE!>FromCompanionBeta<!>::foo
+    val q = <!UNRESOLVED_REFERENCE!>FromCompanionGamma<!>::foo
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = FromDelta::foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesOld.fir.kt
new file mode 100644
index 00000000000..4ada62f2fa3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesOld.fir.kt
@@ -0,0 +1,142 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// See KT-21515 for a class diagram and details
+
+// class is to prevent accidental short-name import
+class O {
+    open class Alpha {
+        open fun foo() = 42
+
+        class FromAlpha {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionAlpha {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class Beta : Alpha() {
+        override fun foo() = 42
+
+        class FromBeta {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionBeta {
+                fun foo() = 42
+            }
+        }
+    }
+
+
+    open class A {
+        open fun foo() = 42
+
+        class FromA {
+            fun foo() = 42
+        }
+
+        companion object : Beta() {
+            class FromCompanionA {
+                fun foo() = 42
+            }
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open fun foo() = 42
+
+        class FromFarAway {
+            fun foo() = 42
+        }
+
+    }
+
+    open class Gamma {
+        open fun foo() = 42
+
+        class FromGamma {
+            fun foo() = 42
+        }
+
+        companion object : FarAway() {
+            class FromCompanionGamma {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class B : A() {
+        override fun foo() = 42
+
+        class FromB {
+            fun foo() = 42
+        }
+
+        companion object : Gamma() {
+            override fun foo() = 42
+
+            class FromCompanionB {
+                fun foo() = 42
+            }
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open fun foo() = 42
+    class FromDelta {
+        fun foo() = 42
+    }
+}
+
+class C : O.B() {
+    override fun foo() = 42
+
+    companion object : Delta() {
+        class FromCompanionC {
+            fun foo() = 42
+        }
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = FromA::foo
+    val d = FromB::foo
+
+    // VISIBLE: Classifiers from our own companion
+    val n = FromCompanionC::foo
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = <!UNRESOLVED_REFERENCE!>A<!>::foo
+    val b = <!UNRESOLVED_REFERENCE!>A<!>::foo
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = FromCompanionA::foo
+    val f = FromCompanionB::foo
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = <!UNRESOLVED_REFERENCE!>Alpha<!>::foo
+    val h = <!UNRESOLVED_REFERENCE!>Beta<!>::foo
+    val i = <!UNRESOLVED_REFERENCE!>Gamma<!>::foo
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = FromAlpha::foo
+    val l = FromBeta::foo
+    val m = FromGamma::foo
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = <!UNRESOLVED_REFERENCE!>FromCompanionAlpha<!>::foo
+    val p = <!UNRESOLVED_REFERENCE!>FromCompanionBeta<!>::foo
+    val q = <!UNRESOLVED_REFERENCE!>FromCompanionGamma<!>::foo
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = FromDelta::foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesOldComplexCases.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesOldComplexCases.fir.kt
new file mode 100644
index 00000000000..5902f6f0990
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesOldComplexCases.fir.kt
@@ -0,0 +1,69 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+// ===== Case 1: LHS is a class
+//
+object A {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromBaseCompanion::foo
+    }
+}
+
+// ===== Case 2: LHS is a class with companion object, function comes from class
+
+object B {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                fun foo() = 42
+
+                companion object {}
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromBaseCompanion::foo
+    }
+}
+
+// ==== Case 3: LHS is a class with companion object, function comes from companion
+
+object C {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                companion object {
+                    fun foo() = 42
+                }
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromBaseCompanion::foo
+    }
+}
+
+// ==== Case 4: LHS is an object
+
+object D {
+    open class Base {
+        companion object {
+            object FromBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromBaseCompanion::foo
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesWithQualificationNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesWithQualificationNew.fir.kt
new file mode 100644
index 00000000000..4a72ff41864
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesWithQualificationNew.fir.kt
@@ -0,0 +1,142 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// See KT-21515 for a class diagram and details
+
+// class is to prevent accidental short-name import
+class O {
+    open class Alpha {
+        open fun foo() = 42
+
+        class FromAlpha {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionAlpha {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class Beta : Alpha() {
+        override fun foo() = 42
+
+        class FromBeta {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionBeta {
+                fun foo() = 42
+            }
+        }
+    }
+
+
+    open class A {
+        open fun foo() = 42
+
+        class FromA {
+            fun foo() = 42
+        }
+
+        companion object : Beta() {
+            class FromCompanionA {
+                fun foo() = 42
+            }
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open fun foo() = 42
+
+        class FromFarAway {
+            fun foo() = 42
+        }
+
+    }
+
+    open class Gamma {
+        open fun foo() = 42
+
+        class FromGamma {
+            fun foo() = 42
+        }
+
+        companion object : FarAway() {
+            class FromCompanionGamma {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class B : A() {
+        override fun foo() = 42
+
+        class FromB {
+            fun foo() = 42
+        }
+
+        companion object : Gamma() {
+            override fun foo() = 42
+
+            class FromCompanionB {
+                fun foo() = 42
+            }
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open fun foo() = 42
+    class FromDelta {
+        fun foo() = 42
+    }
+}
+
+class C : O.B() {
+    override fun foo() = 42
+
+    companion object : Delta() {
+        class FromCompanionC {
+            fun foo() = 42
+        }
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = O.A.FromA::foo
+    val d = O.B.FromB::foo
+
+    // VISIBLE: Classifiers from our own companion
+    val n = C.Companion.FromCompanionC::foo
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = O.A::foo
+    val b = O.A::foo
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = O.A.Companion.FromCompanionA::foo
+    val f = O.B.Companion.FromCompanionB::foo
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = O.Alpha::foo
+    val h = O.Beta::foo
+    val i = O.Gamma::foo
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = O.Alpha.FromAlpha::foo
+    val l = O.Beta.FromBeta::foo
+    val m = O.Gamma.FromGamma::foo
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = O.Alpha.Companion.FromCompanionAlpha::foo
+    val p = O.Beta.Companion.FromCompanionBeta::foo
+    val q = O.Gamma.Companion.FromCompanionGamma::foo
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = Delta.FromDelta::foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesWithQualificationOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesWithQualificationOld.fir.kt
new file mode 100644
index 00000000000..365ce45f7b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesWithQualificationOld.fir.kt
@@ -0,0 +1,142 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// See KT-21515 for a class diagram and details
+
+// class is to prevent accidental short-name import
+class O {
+    open class Alpha {
+        open fun foo() = 42
+
+        class FromAlpha {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionAlpha {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class Beta : Alpha() {
+        override fun foo() = 42
+
+        class FromBeta {
+            fun foo() = 42
+        }
+
+        companion object {
+            class FromCompanionBeta {
+                fun foo() = 42
+            }
+        }
+    }
+
+
+    open class A {
+        open fun foo() = 42
+
+        class FromA {
+            fun foo() = 42
+        }
+
+        companion object : Beta() {
+            class FromCompanionA {
+                fun foo() = 42
+            }
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open fun foo() = 42
+
+        class FromFarAway {
+            fun foo() = 42
+        }
+
+    }
+
+    open class Gamma {
+        open fun foo() = 42
+
+        class FromGamma {
+            fun foo() = 42
+        }
+
+        companion object : FarAway() {
+            class FromCompanionGamma {
+                fun foo() = 42
+            }
+        }
+    }
+
+    open class B : A() {
+        override fun foo() = 42
+
+        class FromB {
+            fun foo() = 42
+        }
+
+        companion object : Gamma() {
+            override fun foo() = 42
+
+            class FromCompanionB {
+                fun foo() = 42
+            }
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open fun foo() = 42
+    class FromDelta {
+        fun foo() = 42
+    }
+}
+
+class C : O.B() {
+    override fun foo() = 42
+
+    companion object : Delta() {
+        class FromCompanionC {
+            fun foo() = 42
+        }
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = O.A.FromA::foo
+    val d = O.B.FromB::foo
+
+    // VISIBLE: Classifiers from our own companion
+    val n = FromCompanionC::foo
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = O.A::foo
+    val b = O.A::foo
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = O.A.Companion.FromCompanionA::foo
+    val f = O.B.Companion.FromCompanionB::foo
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = O.Alpha::foo
+    val h = O.Beta::foo
+    val i = O.Gamma::foo
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = O.Alpha.FromAlpha::foo
+    val l = O.Beta.FromBeta::foo
+    val m = O.Gamma.FromGamma::foo
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = O.Alpha.Companion.FromCompanionAlpha::foo
+    val p = O.Beta.Companion.FromCompanionBeta::foo
+    val q = O.Gamma.Companion.FromCompanionGamma::foo
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = Delta.FromDelta::foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectNew.fir.kt
new file mode 100644
index 00000000000..80326a4b109
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectNew.fir.kt
@@ -0,0 +1,99 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c: FromA? = null
+    val d: FromB? = null
+
+    // VISIBLE: Classifiers from our own companion
+    val n: FromCompanionC? = null
+
+    // INVISIBLE: direct superclasses themselves.
+    val a: A? = null
+    val b: B? = null
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e: FromCompanionA? = null
+    val f: FromCompanionB? = null
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g: Alpha? = null
+    val h: Beta? = null
+    val i: Gamma? = null
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k: FromAlpha? = null
+    val l: FromBeta? = null
+    val m: FromGamma? = null
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o: FromCompanionAlpha? = null
+    val p: FromCompanionBeta? = null
+    val q: FromCompanionGamma? = null
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r: FromDelta? = null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectOld.fir.kt
new file mode 100644
index 00000000000..f2d2fb0820e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectOld.fir.kt
@@ -0,0 +1,98 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c: FromA? = null
+    val d: FromB? = null
+
+    // VISIBLE: Classifiers from our own companion
+    val n: FromCompanionC? = null
+
+    // INVISIBLE: direct superclasses themselves.
+    val a: A? = null
+    val b: B? = null
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e: FromCompanionA? = null
+    val f: FromCompanionB? = null
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g: Alpha? = null
+    val h: Beta? = null
+    val i: Gamma? = null
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k: FromAlpha? = null
+    val l: FromBeta? = null
+    val m: FromGamma? = null
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o: FromCompanionAlpha? = null
+    val p: FromCompanionBeta? = null
+    val q: FromCompanionGamma? = null
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r: FromDelta? = null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectWithQualificationNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectWithQualificationNew.fir.kt
new file mode 100644
index 00000000000..cee85fc989c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectWithQualificationNew.fir.kt
@@ -0,0 +1,99 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c: O.A.FromA? = null
+    val d: O.B.FromB? = null
+
+    // VISIBLE: Classifiers from our own companion
+    val n: C.Companion.FromCompanionC? = null
+
+    // INVISIBLE: direct superclasses themselves.
+    val a: O.A? = null
+    val b: O.B? = null
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e: O.A.Companion.FromCompanionA? = null
+    val f: O.B.Companion.FromCompanionB? = null
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g: O.Alpha? = null
+    val h: O.Beta? = null
+    val i: O.Gamma? = null
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k: O.Alpha.FromAlpha? = null
+    val l: O.Beta.FromBeta? = null
+    val m: O.Gamma.FromGamma? = null
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o: O.Alpha.Companion.FromCompanionAlpha? = null
+    val p: O.Beta.Companion.FromCompanionBeta? = null
+    val q: O.Gamma.Companion.FromCompanionGamma? = null
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r: Delta.FromDelta? = null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectWithQualificationOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectWithQualificationOld.fir.kt
new file mode 100644
index 00000000000..6a65b624428
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/classifierFromCompanionObjectWithQualificationOld.fir.kt
@@ -0,0 +1,98 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c: O.A.FromA? = null
+    val d: O.B.FromB? = null
+
+    // VISIBLE: Classifiers from our own companion
+    val n: C.Companion.FromCompanionC? = null
+
+    // INVISIBLE: direct superclasses themselves.
+    val a: O.A? = null
+    val b: O.B? = null
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e: O.A.Companion.FromCompanionA? = null
+    val f: O.B.Companion.FromCompanionB? = null
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g: O.Alpha? = null
+    val h: O.Beta? = null
+    val i: O.Gamma? = null
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k: O.Alpha.FromAlpha? = null
+    val l: O.Beta.FromBeta? = null
+    val m: O.Gamma.FromGamma? = null
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o: O.Alpha.Companion.FromCompanionAlpha? = null
+    val p: O.Beta.Companion.FromCompanionBeta? = null
+    val q: O.Gamma.Companion.FromCompanionGamma? = null
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r: Delta.FromDelta? = null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/classifierIsVisibleByTwoPaths.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/classifierIsVisibleByTwoPaths.fir.kt
new file mode 100644
index 00000000000..bdc9c72d601
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/classifierIsVisibleByTwoPaths.fir.kt
@@ -0,0 +1,17 @@
+open class A {
+    class FromA {
+        fun foo() = 42
+    }
+}
+
+class B : A() {
+    companion object : A() { }
+
+    // we're seeing FromA here by two paths: one is deprecated (via companion object), and another one is not,
+    // so we shouldn't see deprecation warning
+    val a: FromA? = null
+
+    val b = FromA::foo
+
+    val c = FromA()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedNew.fir.kt
new file mode 100644
index 00000000000..118f24674a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedNew.fir.kt
@@ -0,0 +1,100 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a open class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        open class FromAlpha
+
+        companion object {
+            open class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        open class FromBeta
+
+        companion object {
+            open class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        open class FromA
+
+        companion object : Beta() {
+            open class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open class FromFarAway
+
+    }
+
+    open class Gamma {
+        open class FromGamma
+        companion object : FarAway() {
+            open class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        open class FromB
+
+        companion object : Gamma() {
+            open class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open class FromDelta
+}
+
+open class C : O.B() {
+    companion object : Delta() {
+        open class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    open class c : FromA()
+    open class d : FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    open class n : FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    open class a : A()
+    open class b : B()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    open class e : FromCompanionA()
+    open class f : FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    open class g : Alpha()
+    open class h : Beta()
+    open class i : Gamma()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    open class k : FromAlpha()
+    open class l : FromBeta()
+    open class m : FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    open class o : FromCompanionAlpha()
+    open class p : FromCompanionBeta()
+    open class q : FromCompanionGamma()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    open class r : FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedOld.fir.kt
new file mode 100644
index 00000000000..99dfc2d318b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedOld.fir.kt
@@ -0,0 +1,100 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a open class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        open class FromAlpha
+
+        companion object {
+            open class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        open class FromBeta
+
+        companion object {
+            open class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        open class FromA
+
+        companion object : Beta() {
+            open class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open class FromFarAway
+
+    }
+
+    open class Gamma {
+        open class FromGamma
+        companion object : FarAway() {
+            open class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        open class FromB
+
+        companion object : Gamma() {
+            open class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open class FromDelta
+}
+
+open class C : O.B() {
+    companion object : Delta() {
+        open class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    open class c : FromA()
+    open class d : FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    open class n : FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    open class a : A()
+    open class b : B()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    open class e : FromCompanionA()
+    open class f : FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    open class g : Alpha()
+    open class h : Beta()
+    open class i : Gamma()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    open class k : FromAlpha()
+    open class l : FromBeta()
+    open class m : FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    open class o : FromCompanionAlpha()
+    open class p : FromCompanionBeta()
+    open class q : FromCompanionGamma()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    open class r : FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedWithQualificationNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedWithQualificationNew.fir.kt
new file mode 100644
index 00000000000..f1abf117b2d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedWithQualificationNew.fir.kt
@@ -0,0 +1,100 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a open class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        open class FromAlpha
+
+        companion object {
+            open class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        open class FromBeta
+
+        companion object {
+            open class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        open class FromA
+
+        companion object : Beta() {
+            open class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open class FromFarAway
+
+    }
+
+    open class Gamma {
+        open class FromGamma
+        companion object : FarAway() {
+            open class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        open class FromB
+
+        companion object : Gamma() {
+            open class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open class FromDelta
+}
+
+open class C : O.B() {
+    companion object : Delta() {
+        open class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    open class c : O.A.FromA()
+    open class d : O.B.FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    open class n : C.Companion.FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    open class a : O.A()
+    open class b : O.B()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    open class e : O.A.Companion.FromCompanionA()
+    open class f : O.B.Companion.FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    open class g : O.Alpha()
+    open class h : O.Beta()
+    open class i : O.Gamma()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    open class k : O.Alpha.FromAlpha()
+    open class l : O.Beta.FromBeta()
+    open class m : O.Gamma.FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    open class o : O.Alpha.Companion.FromCompanionAlpha()
+    open class p : O.Beta.Companion.FromCompanionBeta()
+    open class q : O.Gamma.Companion.FromCompanionGamma()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    open class r : Delta.FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedWithQualificationOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedWithQualificationOld.fir.kt
new file mode 100644
index 00000000000..ea97e72b0c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/inheritedFromDeprecatedWithQualificationOld.fir.kt
@@ -0,0 +1,100 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a open class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        open class FromAlpha
+
+        companion object {
+            open class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        open class FromBeta
+
+        companion object {
+            open class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        open class FromA
+
+        companion object : Beta() {
+            open class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        open class FromFarAway
+
+    }
+
+    open class Gamma {
+        open class FromGamma
+        companion object : FarAway() {
+            open class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        open class FromB
+
+        companion object : Gamma() {
+            open class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    open class FromDelta
+}
+
+open class C : O.B() {
+    companion object : Delta() {
+        open class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    open class c : O.A.FromA()
+    open class d : O.B.FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    open class n : C.Companion.FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    open class a : O.A()
+    open class b : O.B()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    open class e : O.A.Companion.FromCompanionA()
+    open class f : O.B.Companion.FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    open class g : O.Alpha()
+    open class h : O.Beta()
+    open class i : O.Gamma()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    open class k : O.Alpha.FromAlpha()
+    open class l : O.Beta.FromBeta()
+    open class m : O.Gamma.FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    open class o : O.Alpha.Companion.FromCompanionAlpha()
+    open class p : O.Beta.Companion.FromCompanionBeta()
+    open class q : O.Gamma.Companion.FromCompanionGamma()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    open class r : Delta.FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaNew.fir.kt
new file mode 100644
index 00000000000..03695a19fb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaNew.fir.kt
@@ -0,0 +1,48 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: test/Java.java
+package test;
+
+public class Java {
+    public static void method() { }
+    public static int property = 42;
+    public static class Classifier { }
+    public static void syntheticSam(Runnable r) { }
+
+    public static int getStaticSyntheticProperty() { return 42; }
+    public static int setStaticSyntheticProperty(int x) { return 42; }
+
+    public int getInstanceSyntheticProperty() { return 42; }
+    public int setInstanceSyntheticProperty(int x) { return 42; }
+}
+
+// FILE: Kotlin.kt
+package test
+
+open class Base {
+    companion object : Java() {
+
+    }
+}
+
+class Derived : Base() {
+    fun test(javaStaticInTypePosition: Classifier) {
+        <!UNRESOLVED_REFERENCE!>method<!>()
+        <!UNRESOLVED_REFERENCE!>property<!>
+        Classifier()
+        <!UNRESOLVED_REFERENCE!>syntheticSam<!> { }
+
+        // Instance members shouldn't be affected, but we check them, just in case
+        val y = <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!> = 43
+
+        // Note that statics actually aren't converted into synthetic property in Kotlin
+        val x = <!UNRESOLVED_REFERENCE!>syntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>syntheticProperty<!> = 42
+    }
+
+    class JavaStaticInSupertypeList : Classifier() {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaOld.fir.kt
new file mode 100644
index 00000000000..fcb485158b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaOld.fir.kt
@@ -0,0 +1,48 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: test/Java.java
+package test;
+
+public class Java {
+    public static void method() { }
+    public static int property = 42;
+    public static class Classifier { }
+    public static void syntheticSam(Runnable r) { }
+
+    public static int getStaticSyntheticProperty() { return 42; }
+    public static int setStaticSyntheticProperty(int x) { return 42; }
+
+    public int getInstanceSyntheticProperty() { return 42; }
+    public int setInstanceSyntheticProperty(int x) { return 42; }
+}
+
+// FILE: Kotlin.kt
+package test
+
+open class Base {
+    companion object : Java() {
+
+    }
+}
+
+class Derived : Base() {
+    fun test(javaStaticInTypePosition: Classifier) {
+        <!UNRESOLVED_REFERENCE!>method<!>()
+        <!UNRESOLVED_REFERENCE!>property<!>
+        Classifier()
+        <!UNRESOLVED_REFERENCE!>syntheticSam<!> { }
+
+        // Instance members shouldn't be affected, but we check them, just in case
+        val y = <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!> = 43
+
+        // Note that statics actually aren't converted into synthetic property in Kotlin
+        val x = <!UNRESOLVED_REFERENCE!>syntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>syntheticProperty<!> = 42
+    }
+
+    class JavaStaticInSupertypeList : Classifier() {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaWithQualificationNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaWithQualificationNew.fir.kt
new file mode 100644
index 00000000000..7ffea50e305
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaWithQualificationNew.fir.kt
@@ -0,0 +1,53 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: test/Java.java
+package test;
+
+public class Java {
+    public static void method() { }
+    public static int property = 42;
+    public static class Classifier { }
+    public static void syntheticSam(Runnable r) { }
+
+    public static int getStaticSyntheticProperty() { return 42; }
+    public static int setStaticSyntheticProperty(int x) { return 42; }
+
+    public int getInstanceSyntheticProperty() { return 42; }
+    public int setInstanceSyntheticProperty(int x) { return 42; }
+}
+
+// FILE: Kotlin.kt
+package test
+
+import test.Java.method
+import test.Java.Classifier
+import test.Java.property
+import test.Java.syntheticSam
+
+open class Base {
+    companion object : Java() {
+
+    }
+}
+
+class Derived : Base() {
+    fun test(javaStaticInTypePosition: Classifier) {
+        method()
+        property
+        Classifier()
+        syntheticSam { }
+
+        // Instance members shouldn't be affected, but we check them, just in case
+        val y = <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!> = 43
+
+        // Note that statics actually aren't converted into synthetic property in Kotlin
+        val x = <!UNRESOLVED_REFERENCE!>syntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>syntheticProperty<!> = 42
+    }
+
+    class JavaStaticInSupertypeList : Classifier() {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaWithQualificationOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaWithQualificationOld.fir.kt
new file mode 100644
index 00000000000..5ecec00f0a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/staticsFromJavaWithQualificationOld.fir.kt
@@ -0,0 +1,53 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: test/Java.java
+package test;
+
+public class Java {
+    public static void method() { }
+    public static int property = 42;
+    public static class Classifier { }
+    public static void syntheticSam(Runnable r) { }
+
+    public static int getStaticSyntheticProperty() { return 42; }
+    public static int setStaticSyntheticProperty(int x) { return 42; }
+
+    public int getInstanceSyntheticProperty() { return 42; }
+    public int setInstanceSyntheticProperty(int x) { return 42; }
+}
+
+// FILE: Kotlin.kt
+package test
+
+import test.Java.method
+import test.Java.Classifier
+import test.Java.property
+import test.Java.syntheticSam
+
+open class Base {
+    companion object : Java() {
+
+    }
+}
+
+class Derived : Base() {
+    fun test(javaStaticInTypePosition: Classifier) {
+        method()
+        property
+        Classifier()
+        syntheticSam { }
+
+        // Instance members shouldn't be affected, but we check them, just in case
+        val y = <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>instanceSyntheticProperty<!> = 43
+
+        // Note that statics actually aren't converted into synthetic property in Kotlin
+        val x = <!UNRESOLVED_REFERENCE!>syntheticProperty<!>
+        <!UNRESOLVED_REFERENCE!>syntheticProperty<!> = 42
+    }
+
+    class JavaStaticInSupertypeList : Classifier() {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorNew.fir.kt
new file mode 100644
index 00000000000..b9552eb18a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorNew.fir.kt
@@ -0,0 +1,100 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = FromA()
+    val d = FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    val n = FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = <!UNRESOLVED_REFERENCE!>A<!>()
+    val b = <!UNRESOLVED_REFERENCE!>B<!>()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = FromCompanionA()
+    val f = FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = <!UNRESOLVED_REFERENCE!>Alpha<!>()
+    val h = <!UNRESOLVED_REFERENCE!>Beta<!>()
+    val i = <!UNRESOLVED_REFERENCE!>Gamma<!>()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = FromAlpha()
+    val l = FromBeta()
+    val m = FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = <!UNRESOLVED_REFERENCE!>FromCompanionAlpha<!>()
+    val p = <!UNRESOLVED_REFERENCE!>FromCompanionBeta<!>()
+    val q = <!UNRESOLVED_REFERENCE!>FromCompanionGamma<!>()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorOld.fir.kt
new file mode 100644
index 00000000000..a3ad9f862f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorOld.fir.kt
@@ -0,0 +1,99 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = FromA()
+    val d = FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    val n = FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = <!UNRESOLVED_REFERENCE!>A<!>()
+    val b = <!UNRESOLVED_REFERENCE!>B<!>()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = FromCompanionA()
+    val f = FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = <!UNRESOLVED_REFERENCE!>Alpha<!>()
+    val h = <!UNRESOLVED_REFERENCE!>Beta<!>()
+    val i = <!UNRESOLVED_REFERENCE!>Gamma<!>()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = FromAlpha()
+    val l = FromBeta()
+    val m = FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = <!UNRESOLVED_REFERENCE!>FromCompanionAlpha<!>()
+    val p = <!UNRESOLVED_REFERENCE!>FromCompanionBeta<!>()
+    val q = <!UNRESOLVED_REFERENCE!>FromCompanionGamma<!>()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorWithQualificationNew.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorWithQualificationNew.fir.kt
new file mode 100644
index 00000000000..2a1da9d91d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorWithQualificationNew.fir.kt
@@ -0,0 +1,100 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = O.A.FromA()
+    val d = O.B.FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    val n = C.Companion.FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = O.A()
+    val b = O.B()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = O.A.Companion.FromCompanionA()
+    val f = O.B.Companion.FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = O.Alpha()
+    val h = O.Beta()
+    val i = O.Gamma()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = O.Alpha.FromAlpha()
+    val l = O.Beta.FromBeta()
+    val m = O.Gamma.FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = O.Alpha.Companion.FromCompanionAlpha()
+    val p = O.Beta.Companion.FromCompanionBeta()
+    val q = O.Gamma.Companion.FromCompanionGamma()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = Delta.FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorWithQualificationOld.fir.kt b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorWithQualificationOld.fir.kt
new file mode 100644
index 00000000000..ab80273e1c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt21515/useDeprecatedConstructorWithQualificationOld.fir.kt
@@ -0,0 +1,100 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// See KT-21515 for a class diagram and details
+
+// Object is to prevent accidental short-name import
+object O {
+    open class Alpha {
+        class FromAlpha
+
+        companion object {
+            class FromCompanionAlpha
+        }
+    }
+
+    open class Beta : Alpha() {
+        class FromBeta
+
+        companion object {
+            class FromCompanionBeta
+        }
+    }
+
+
+    open class A {
+        class FromA
+
+        companion object : Beta() {
+            class FromCompanionA
+        }
+    }
+
+//////////////////////////
+
+    open class FarAway {
+        class FromFarAway
+
+    }
+
+    open class Gamma {
+        class FromGamma
+        companion object : FarAway() {
+            class FromCompanionGamma
+        }
+    }
+
+    open class B : A() {
+        class FromB
+
+        companion object : Gamma() {
+            class FromCompanionB
+        }
+    }
+}
+
+///////////////////////////////
+
+
+open class Delta {
+    class FromDelta
+}
+
+class C : O.B() {
+    companion object : Delta() {
+        class FromCompanionC
+    }
+
+    // VISIBLE: Classifiers from direct superclasses
+    val c = O.A.FromA()
+    val d = O.B.FromB()
+
+    // VISIBLE: Classifiers from our own companion
+    val n = C.Companion.FromCompanionC()
+
+    // INVISIBLE: direct superclasses themselves.
+    val a = O.A()
+    val b = O.B()
+
+    // DEPRECATED: Classifiers from companions of direct superclasses
+    val e = O.A.Companion.FromCompanionA()
+    val f = O.B.Companion.FromCompanionB()
+
+    // INVISIBLE: "cousin" supertypes themselves
+    val g = O.Alpha()
+    val h = O.Beta()
+    val i = O.Gamma()
+
+    // DEPRECATED: classifiers from "cousin" superclasses
+    val k = O.Alpha.FromAlpha()
+    val l = O.Beta.FromBeta()
+    val m = O.Gamma.FromGamma()
+
+    // INVISIBLE: We don't see classifiers from companions of "cousin" superclasses
+    val o = O.Alpha.Companion.FromCompanionAlpha()
+    val p = O.Beta.Companion.FromCompanionBeta()
+    val q = O.Gamma.Companion.FromCompanionGamma()
+
+    // DEPRECATED: Classifiers from supertypes of our own companion
+    val r = Delta.FromDelta()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt2240.fir.kt b/compiler/testData/diagnostics/tests/objects/kt2240.fir.kt
new file mode 100644
index 00000000000..dc03783e2fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt2240.fir.kt
@@ -0,0 +1,13 @@
+package a
+
+//KT-2240 Wrong overload resolution ambiguity when object literal is involved
+
+class A {}
+
+fun <T> A.foo(f : T) {}
+
+val o = object {
+    fun <T> foo(f: T) {
+        A().foo(f) // Ambiguity here!
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/kt5527.fir.kt b/compiler/testData/diagnostics/tests/objects/kt5527.fir.kt
new file mode 100644
index 00000000000..24c1fc278ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/kt5527.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+object Boo {}
+class A {
+    object Boo {}
+}
+
+fun foo() {
+    val i1: Int = Boo
+    val i2: Int = A.Boo
+    <!INAPPLICABLE_CANDIDATE!>useInt<!>(Boo)
+    <!INAPPLICABLE_CANDIDATE!>useInt<!>(A.Boo)
+}
+fun bar() {
+    val i1: Int = Unit
+    <!INAPPLICABLE_CANDIDATE!>useInt<!>(Unit)
+}
+
+fun useInt(i: Int) = i
diff --git a/compiler/testData/diagnostics/tests/objects/localObjectInsideObject.fir.kt b/compiler/testData/diagnostics/tests/objects/localObjectInsideObject.fir.kt
new file mode 100644
index 00000000000..6a593b39d65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/localObjectInsideObject.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+fun foo() {
+    val a = object {
+        val b = object {
+            val c = 42
+        }
+    }
+
+    checkSubtype<Int>(a.b.c)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/localObjects.fir.kt b/compiler/testData/diagnostics/tests/objects/localObjects.fir.kt
new file mode 100644
index 00000000000..0ec89e28f78
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/localObjects.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun foo() {
+    object a {}
+    val b = object {
+        object c {}
+    }
+    b.c
+    class A {
+        object d {}
+    }
+    val f = {
+        object e {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/nestedClassInAnonymousObject.fir.kt b/compiler/testData/diagnostics/tests/objects/nestedClassInAnonymousObject.fir.kt
new file mode 100644
index 00000000000..1a182ce94d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/nestedClassInAnonymousObject.fir.kt
@@ -0,0 +1,11 @@
+class X {
+    val foo = object {
+        class Foo
+    }
+
+    fun test() {
+        object {
+            class Foo
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/objects/objectInsideFun.fir.kt b/compiler/testData/diagnostics/tests/objects/objectInsideFun.fir.kt
new file mode 100644
index 00000000000..481c7c017ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/objectInsideFun.fir.kt
@@ -0,0 +1,11 @@
+interface A {
+    val foo: Int
+    val bar: String
+        get() = ""
+}
+
+fun test(foo: Int, bar: Int) {
+    object : A {
+        override val foo: Int = foo + bar
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/objectLiteralExpressionTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/objects/objectLiteralExpressionTypeMismatch.fir.kt
new file mode 100644
index 00000000000..1c9378ffee8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/objectLiteralExpressionTypeMismatch.fir.kt
@@ -0,0 +1,9 @@
+interface A
+
+interface B
+
+fun test1(): B = object : A {
+}
+
+fun test2(): B = object {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/objects/upperBoundViolated.fir.kt b/compiler/testData/diagnostics/tests/objects/upperBoundViolated.fir.kt
new file mode 100644
index 00000000000..86ba09f738d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/objects/upperBoundViolated.fir.kt
@@ -0,0 +1,9 @@
+interface Trait<N : Number>
+
+object O1 : Trait<Int>
+
+object O2 : Trait<String>
+
+class C {
+    companion object : Trait<IntRange>
+}
diff --git a/compiler/testData/diagnostics/tests/operatorRem/DeprecatedModAssignOperatorConventions.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/DeprecatedModAssignOperatorConventions.fir.kt
new file mode 100644
index 00000000000..8dbd3ff4ab0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/DeprecatedModAssignOperatorConventions.fir.kt
@@ -0,0 +1,43 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class OldAndNew {
+    operator fun modAssign(x: Int) {}
+    operator fun remAssign(x: Int) {}
+}
+
+class OnlyOld {
+    operator fun modAssign(x: Int) {}
+}
+
+class OnlyNew {
+    operator fun remAssign(x: Int) {}
+}
+
+class Sample
+
+operator fun Sample.modAssign(x: Int) {}
+operator fun Sample.remAssign(x: Int) {}
+
+class ModAndRemAssign {
+    operator fun mod(x: Int): ModAndRemAssign = ModAndRemAssign()
+    operator fun remAssign(x: Int) {}
+}
+
+fun test() {
+    val oldAndNew = OldAndNew()
+    oldAndNew %= 1
+
+    val onlyOld = OnlyOld()
+    <!INAPPLICABLE_CANDIDATE!>onlyOld %= 1<!>
+
+    val onlyNew = OnlyNew()
+    onlyNew %= 1
+
+    val sample = Sample()
+    sample %= 1
+
+    var modAndRemAssign = ModAndRemAssign()
+    modAndRemAssign %= 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/DeprecatedModOperatorConventions.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/DeprecatedModOperatorConventions.fir.kt
new file mode 100644
index 00000000000..2b1cd615b4c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/DeprecatedModOperatorConventions.fir.kt
@@ -0,0 +1,37 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class OldAndNew {
+    operator fun mod(x: Int) {}
+    operator fun rem(x: Int) {}
+}
+
+class OnlyOld {
+    operator fun mod(x: Int) {}
+}
+
+class OnlyNew {
+    operator fun rem(x: Int) {}
+}
+
+class Sample
+
+operator fun Sample.mod(x: Int) {}
+operator fun Sample.rem(x: Int) {}
+
+class IntAndUnit {
+    operator fun mod(x: Int) = 0
+    operator fun rem(x: Int): Int = 0
+}
+
+fun test() {
+    OldAndNew() % 1
+    OnlyOld() <!INAPPLICABLE_CANDIDATE!>%<!> 1
+    OnlyNew() % 1
+    Sample() % 1
+
+    takeInt(IntAndUnit() % 1)
+}
+
+fun takeInt(x: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/deprecatedModConvention.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/deprecatedModConvention.fir.kt
new file mode 100644
index 00000000000..990401d58be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/deprecatedModConvention.fir.kt
@@ -0,0 +1,38 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object ModAndRem {
+    operator fun mod(x: Int) {}
+    operator fun rem(x: Int) {}
+}
+
+object OldMod {
+    operator fun mod(x: Int) {}
+}
+
+object ModAndRemExtension
+operator fun ModAndRemExtension.mod(x: Int) {}
+operator fun ModAndRemExtension.rem(x: Int) {}
+
+object ModExtension
+operator fun ModExtension.mod(x: Int) {}
+
+object ModMemberAndRemExtension {
+    operator fun mod(x: Int) {}
+}
+
+operator fun ModMemberAndRemExtension.rem(x: Int) {}
+
+fun foo() {
+    ModAndRem % 1
+    OldMod <!INAPPLICABLE_CANDIDATE!>%<!> 1
+
+    ModAndRemExtension % 1
+
+    ModExtension <!INAPPLICABLE_CANDIDATE!>%<!> 1
+
+    ModMemberAndRemExtension % 1
+
+    OldMod.mod(1)
+    ModExtension.mod(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/doNotResolveToInapplicableRem.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/doNotResolveToInapplicableRem.fir.kt
new file mode 100644
index 00000000000..3c5b319096e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/doNotResolveToInapplicableRem.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object OldMod {
+    operator fun mod(x: Int) {}
+}
+
+object RemExtension
+operator fun RemExtension.rem(x: Int) {}
+
+fun foo() {
+    OldMod <!INAPPLICABLE_CANDIDATE!>%<!> 123
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/errorOnExplicitModCall.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/errorOnExplicitModCall.fir.kt
new file mode 100644
index 00000000000..7a4fd584c21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/errorOnExplicitModCall.fir.kt
@@ -0,0 +1,3 @@
+fun test() {
+    1.mod(3)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/forbiddenModOperatorConvention.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/forbiddenModOperatorConvention.fir.kt
new file mode 100644
index 00000000000..1b7ad2ad8af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/forbiddenModOperatorConvention.fir.kt
@@ -0,0 +1,32 @@
+// !LANGUAGE: +ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object ModAndRem {
+    operator fun mod(x: Int) {}
+    operator fun rem(x: Int) {}
+
+    operator fun modAssign(x: Int) {}
+    operator fun remAssign(x: Int) {}
+}
+
+object JustMod {
+    operator fun mod(x: Int) {}
+    operator fun modAssign(x: Int) {}
+}
+
+fun foo() {
+    ModAndRem % 1
+    ModAndRem.mod(1)
+    ModAndRem.rem(1)
+
+    JustMod <!UNRESOLVED_REFERENCE!>%<!> 1
+    JustMod.mod(1)
+
+    val r = ModAndRem
+    r %= 1
+    r.remAssign(1)
+
+    val m = JustMod
+    <!UNRESOLVED_REFERENCE!>m %= 1<!>
+    m.modAssign(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/modWithRemAssign.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/modWithRemAssign.fir.kt
new file mode 100644
index 00000000000..1f88d50ea19
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/modWithRemAssign.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -EXTENSION_SHADOWED_BY_MEMBER
+
+class ModAndRemAssign {
+    operator fun mod(x: Int) = ModAndRemAssign()
+    operator fun mod(x: String) = ModAndRemAssign()
+    operator fun modAssign(x: String) {}
+    operator fun remAssign(x: Int) {}
+}
+
+operator fun ModAndRemAssign.mod(x: String) = ModAndRemAssign()
+operator fun ModAndRemAssign.modAssign(x: String) {}
+
+fun test() {
+    val modAndRemAssign = ModAndRemAssign()
+    modAndRemAssign %= 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/noDeprecatedModConventionWithoutFeature.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/noDeprecatedModConventionWithoutFeature.fir.kt
new file mode 100644
index 00000000000..b3e37e080ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/noDeprecatedModConventionWithoutFeature.fir.kt
@@ -0,0 +1,38 @@
+// !LANGUAGE: -OperatorRem
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object ModAndRem {
+    operator fun mod(x: Int) {}
+    operator fun rem(x: Int) {}
+}
+
+object OldMod {
+    operator fun mod(x: Int) {}
+}
+
+object ModAndRemExtension
+operator fun ModAndRemExtension.mod(x: Int) {}
+operator fun ModAndRemExtension.rem(x: Int) {}
+
+object ModExtension
+operator fun ModExtension.mod(x: Int) {}
+
+object ModMemberAndRemExtension {
+    operator fun mod(x: Int) {}
+}
+
+operator fun ModMemberAndRemExtension.rem(x: Int) {}
+
+fun foo() {
+    ModAndRem % 1
+    OldMod <!INAPPLICABLE_CANDIDATE!>%<!> 1
+
+    ModAndRemExtension % 1
+
+    ModExtension <!INAPPLICABLE_CANDIDATE!>%<!> 1
+
+    ModMemberAndRemExtension % 1
+
+    OldMod.mod(1)
+    ModExtension.mod(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/noOperatorRemFeature.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/noOperatorRemFeature.fir.kt
new file mode 100644
index 00000000000..8b8327f0836
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/noOperatorRemFeature.fir.kt
@@ -0,0 +1,36 @@
+// !LANGUAGE: -OperatorRem
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -EXTENSION_SHADOWED_BY_MEMBER
+
+class Foo {
+    operator fun rem(x: Int): Foo = Foo()
+}
+
+class Bar {
+    operator fun remAssign(x: Int) {}
+}
+
+class Baz {
+    companion object {
+        operator fun rem(x: Int) {}
+        operator fun Int.rem(x: Int) {}
+    }
+}
+
+operator fun Baz.rem(x: Int) {}
+
+fun local() {
+    operator fun Int.rem(x: Int) {}
+    operator fun String.remAssign(x: Int) {}
+}
+
+fun noOverflow() {
+    (-1).mod(5)
+}
+
+fun builtIns(b: Byte, s: Short) {
+    var a = 1 % 2
+    a %= 3
+    1.mod(2)
+    b % s
+    1.0 % 2.0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/noWarningForModFromBuiltinsWhenApi1_0_after.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/noWarningForModFromBuiltinsWhenApi1_0_after.fir.kt
new file mode 100644
index 00000000000..4051aa674a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/noWarningForModFromBuiltinsWhenApi1_0_after.fir.kt
@@ -0,0 +1,48 @@
+// !LANGUAGE: +ProhibitOperatorMod
+// !WITH_NEW_INFERENCE
+// !API_VERSION: 1.0
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -EXTENSION_SHADOWED_BY_MEMBER
+
+class Foo {
+    operator fun rem(x: Int): Foo = Foo()
+}
+
+class Bar {
+    operator fun remAssign(x: Int) {}
+}
+
+class Baz {
+    companion object {
+        operator fun rem(x: Int) {}
+        operator fun Int.rem(x: Int) {}
+    }
+}
+
+operator fun Baz.rem(x: Int) {}
+
+fun local() {
+    operator fun Int.rem(x: Int) {}
+    operator fun String.remAssign(x: Int) {}
+}
+
+class WithMod {
+    operator fun mod(other: WithMod) = this
+
+    fun test() {
+        val a = this <!INAPPLICABLE_CANDIDATE!>%<!> this
+        var b = this.mod(this)
+        <!UNRESOLVED_REFERENCE!>b %= this<!>
+    }
+}
+
+fun noOverflow() {
+    (-1).mod(5)
+}
+
+fun builtIns(b: Byte, s: Short) {
+    var a = 1 % 2
+    a %= 3
+    1.mod(2)
+    b % s
+    1.0 % 2.0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/noWarningForModFromBuiltinsWhenApi1_0_before.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/noWarningForModFromBuiltinsWhenApi1_0_before.fir.kt
new file mode 100644
index 00000000000..ff50595bd9d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/noWarningForModFromBuiltinsWhenApi1_0_before.fir.kt
@@ -0,0 +1,48 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !WITH_NEW_INFERENCE
+// !API_VERSION: 1.0
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -EXTENSION_SHADOWED_BY_MEMBER
+
+class Foo {
+    operator fun rem(x: Int): Foo = Foo()
+}
+
+class Bar {
+    operator fun remAssign(x: Int) {}
+}
+
+class Baz {
+    companion object {
+        operator fun rem(x: Int) {}
+        operator fun Int.rem(x: Int) {}
+    }
+}
+
+operator fun Baz.rem(x: Int) {}
+
+fun local() {
+    operator fun Int.rem(x: Int) {}
+    operator fun String.remAssign(x: Int) {}
+}
+
+class WithMod {
+    operator fun mod(other: WithMod) = this
+
+    fun test() {
+        val a = this <!INAPPLICABLE_CANDIDATE!>%<!> this
+        var b = this.mod(this)
+        <!UNRESOLVED_REFERENCE!>b %= this<!>
+    }
+}
+
+fun noOverflow() {
+    (-1).mod(5)
+}
+
+fun builtIns(b: Byte, s: Short) {
+    var a = 1 % 2
+    a %= 3
+    1.mod(2)
+    b % s
+    1.0 % 2.0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/numberRemConversions.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/numberRemConversions.fir.kt
new file mode 100644
index 00000000000..9ba8553cda5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/numberRemConversions.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun fooInt(p: Int) = p
+fun fooLong(p: Long) = p
+fun fooByte(p: Byte) = p
+fun fooShort(p: Short) = p
+
+fun test() {
+    fooInt(1 % 1)
+    fooByte(1 % 1)
+    fooLong(1 % 1)
+    fooShort(1 % 1)
+}
+
+public operator fun Int.rem(other: Int): Int = 0
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/operatorRem.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/operatorRem.fir.kt
new file mode 100644
index 00000000000..7cd65cc45ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/operatorRem.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+
+class Foo {
+    operator fun rem(x: Int): Foo = Foo()
+}
+
+class Bar {
+    operator fun remAssign(x: Int) {}
+}
+
+fun baz() {
+    val f = Foo() % 1
+    val b = Bar()
+    b %= 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/preferRemAsExtentionOverMod.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/preferRemAsExtentionOverMod.fir.kt
new file mode 100644
index 00000000000..3695372a668
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/preferRemAsExtentionOverMod.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+}
+operator fun Foo.mod(x: Int): Foo = Foo()
+operator fun Foo.rem(x: Int): Int = 0
+
+fun foo() {
+    takeInt(Foo() % 1)
+}
+
+fun takeInt(x: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/preferRemAsMemberOverMod.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/preferRemAsMemberOverMod.fir.kt
new file mode 100644
index 00000000000..eec75b34f0c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/preferRemAsMemberOverMod.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    operator fun mod(x: Int): Foo = Foo()
+    operator fun rem(x: Int): Int = 0
+}
+
+fun foo() {
+    takeInt(Foo() % 1)
+}
+
+fun takeInt(x: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/preferRemFromCompanionObjectOverRem.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/preferRemFromCompanionObjectOverRem.fir.kt
new file mode 100644
index 00000000000..acf62c6d659
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/preferRemFromCompanionObjectOverRem.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A {
+    companion object {
+        operator fun A.rem(x: Int) = 0
+    }
+
+    fun test() {
+        operator fun A.mod(x: Int) = ""
+
+        takeInt(A() % 123)
+    }
+}
+
+fun takeInt(x: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/preferRemOverModInLocalFunctions.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/preferRemOverModInLocalFunctions.fir.kt
new file mode 100644
index 00000000000..d7059144f35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/preferRemOverModInLocalFunctions.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object B
+
+class A {
+    operator fun B.rem(x: Int) = 0
+}
+
+fun test1() {
+    operator fun B.mod(x: Int) = ""
+
+    with(A()) {
+        takeInt(B % 10)
+    }
+}
+
+class C {
+    operator fun B.mod(x: Int) = ""
+}
+
+fun test2() {
+    operator fun B.rem(x: Int) = 0
+
+    with(C()) {
+        takeInt(B % 10)
+    }
+}
+
+fun takeInt(x: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/preferRemWithImplicitReceivers.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/preferRemWithImplicitReceivers.fir.kt
new file mode 100644
index 00000000000..7778fdb28d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/preferRemWithImplicitReceivers.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A {
+    operator fun Int.mod(s: String) = 4
+}
+
+class B {
+    operator fun Int.rem(s: String) = ""
+}
+
+fun test() {
+    with(B()) {
+        with(A()) {
+            <!INAPPLICABLE_CANDIDATE!>takeString<!>(1 % "")
+        }
+    }
+}
+
+fun takeString(s: String) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/prefereRemAsExtensionOverMemberMod.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/prefereRemAsExtensionOverMemberMod.fir.kt
new file mode 100644
index 00000000000..0b7bcaef8fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/prefereRemAsExtensionOverMemberMod.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Foo {
+    operator fun mod(x: Int): Foo = Foo()
+}
+
+operator fun Foo.rem(x: Int): Int = 0
+
+
+fun foo() {
+    takeInt(Foo() % 1)
+}
+
+fun takeInt(x: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/remAndRemAssignAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/remAndRemAssignAmbiguity.fir.kt
new file mode 100644
index 00000000000..4f0bc9ff038
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/remAndRemAssignAmbiguity.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object RemAndRemAssign {
+    operator fun rem(x: Int) = RemAndRemAssign
+}
+
+operator fun RemAndRemAssign.remAssign(x: Int) {}
+
+fun test() {
+    var c = RemAndRemAssign
+    <!ASSIGN_OPERATOR_AMBIGUITY!>c %= 1<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/remWithModAndModAssign.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/remWithModAndModAssign.fir.kt
new file mode 100644
index 00000000000..530b5050668
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/remWithModAndModAssign.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -EXTENSION_SHADOWED_BY_MEMBER
+
+class ModAndRemAssign {
+    operator fun mod(x: Int) = ModAndRemAssign()
+    operator fun mod(x: String) = ModAndRemAssign()
+    operator fun modAssign(x: String) {}
+    operator fun rem(x: Int) = ModAndRemAssign()
+}
+
+operator fun ModAndRemAssign.mod(x: String) = ModAndRemAssign()
+operator fun ModAndRemAssign.modAssign(x: String) {}
+
+fun test() {
+    var modAndRemAssign = ModAndRemAssign()
+    modAndRemAssign %= 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/remWithModAssign.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/remWithModAssign.fir.kt
new file mode 100644
index 00000000000..2ceabb24a13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/remWithModAssign.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object RemAndModAssign {
+    operator fun modAssign(x: String) {}
+    operator fun rem(x: Int) = RemAndModAssign
+}
+
+fun test2() {
+    var c = RemAndModAssign
+    c %= 123
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/resolveModIfRemIsHidden.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/resolveModIfRemIsHidden.fir.kt
new file mode 100644
index 00000000000..60c26d0d1d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/resolveModIfRemIsHidden.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -ProhibitOperatorMod
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object A {
+    @Deprecated("Use mod instead", ReplaceWith("mod"), DeprecationLevel.HIDDEN)
+    operator fun rem(x: Int) = 0
+
+    operator fun mod(x: Int) = ""
+}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>takeString<!>(A % 123)
+}
+
+fun takeString(s: String) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/resolveToModWhenNoOperatorRemFeature.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/resolveToModWhenNoOperatorRemFeature.fir.kt
new file mode 100644
index 00000000000..1877165b621
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/resolveToModWhenNoOperatorRemFeature.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: -OperatorRem
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object ModAndRem {
+    operator fun mod(x: Int) = 0
+    operator fun rem(x: Int) = ""
+}
+
+object ModAssignAndRemAssign {
+    operator fun modAssign(x: String) {}
+    operator fun remAssign(x: Int) {}
+}
+
+object RemAndModAssign {
+    operator fun modAssign(x: Int) {}
+    operator fun rem(x: Int) = RemAndModAssign
+}
+
+object OnlyRem {
+    operator fun rem(x: Int) {}
+    operator fun remAssign(x: Int) {}
+}
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>takeInt<!>(ModAndRem % 1)
+
+    val c = ModAssignAndRemAssign
+    <!INAPPLICABLE_CANDIDATE!>c %= ""<!>
+
+    var c1 = RemAndModAssign
+    c1 %= 1
+
+    OnlyRem % 1
+
+    val c2 = OnlyRem
+    c2 %= 1
+}
+
+fun takeInt(x: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/warningOnExplicitModCall1_1.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/warningOnExplicitModCall1_1.fir.kt
new file mode 100644
index 00000000000..30758e5c931
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/warningOnExplicitModCall1_1.fir.kt
@@ -0,0 +1,5 @@
+// !API_VERSION: 1.1
+
+fun test() {
+    1.mod(3)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorRem/warningOnExplicitModCall1_2.fir.kt b/compiler/testData/diagnostics/tests/operatorRem/warningOnExplicitModCall1_2.fir.kt
new file mode 100644
index 00000000000..7f076d9c8d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorRem/warningOnExplicitModCall1_2.fir.kt
@@ -0,0 +1,5 @@
+// !API_VERSION: 1.2
+
+fun test() {
+    1.mod(3)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/AssignOperatorAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/AssignOperatorAmbiguity.fir.kt
new file mode 100644
index 00000000000..2fcd95faf7b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/AssignOperatorAmbiguity.fir.kt
@@ -0,0 +1,17 @@
+//KT-1820 Write test for ASSIGN_OPERATOR_AMBIGUITY
+package kt1820
+
+class MyInt(val i: Int) {
+    operator fun plus(m: MyInt) : MyInt = MyInt(m.i + i)
+}
+
+operator fun Any.plusAssign(a: Any) {}
+
+fun test(m: MyInt) {
+    m += m
+
+    var i = 1
+    <!ASSIGN_OPERATOR_AMBIGUITY!>i += 34<!>
+}
+
+
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/AssignmentOperations.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/AssignmentOperations.fir.kt
new file mode 100644
index 00000000000..6f1790ed0d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/AssignmentOperations.fir.kt
@@ -0,0 +1,40 @@
+class A {
+  operator fun plusAssign(x: Int) {}
+  operator fun minusAssign(x: Int) {}
+  operator fun timesAssign(x: Int) {}
+  operator fun divAssign(x: Int) {}
+  operator fun remAssign(x: Int) {}
+}
+
+fun testVal() {
+  val a = A()
+  a += 1
+  a -= 1
+  a *= 1
+  a /= 1
+  a %= 1
+}
+
+fun testExpr() {
+  A() += 1
+  A() -= 1
+  A() *= 1
+  A() /= 1
+  A() %= 1
+}
+
+class B {
+  operator fun plus(x: Int): B = B()
+  operator fun minus(x: Int): B = B()
+  operator fun times(x: Int): B = B()
+  operator fun div(x: Int): B = B()
+  operator fun rem(x: Int): B = B()
+}
+
+fun testWrong() {
+  <!VARIABLE_EXPECTED!>B()<!> += 1
+  <!VARIABLE_EXPECTED!>B()<!> -= 1
+  <!VARIABLE_EXPECTED!>B()<!> *= 1
+  <!VARIABLE_EXPECTED!>B()<!> /= 1
+  <!VARIABLE_EXPECTED!>B()<!> %= 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/InconsistentGetSet.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/InconsistentGetSet.fir.kt
new file mode 100644
index 00000000000..acb1654a31f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/InconsistentGetSet.fir.kt
@@ -0,0 +1,45 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Legal {
+    operator fun get(i: Int) = 0
+    operator fun set(i: Int, newValue: Int) {}
+    operator fun set(i: Int, newValue: String) {}
+}
+
+fun testLegal() {
+    ++Legal[0]
+    Legal[0]++
+    Legal[0] += 1
+}
+
+object MismatchingTypes {
+    operator fun get(i: Int) = 0
+    operator fun set(i: Int, newValue: String) {}
+}
+
+fun testMismatchingTypes() {
+    <!INAPPLICABLE_CANDIDATE!>++MismatchingTypes[0]<!>
+    <!INAPPLICABLE_CANDIDATE!>MismatchingTypes[0]++<!>
+    MismatchingTypes[0] += 1
+}
+
+object MismatchingArities1 {
+    operator fun get(i: Int) = 0
+    operator fun set(i: Int, j: Int, newValue: Int) {}
+}
+
+object MismatchingArities2 {
+    operator fun get(i: Int, j: Int) = 0
+    operator fun set(i: Int, newValue: Int) {}
+}
+
+fun testMismatchingArities() {
+    <!INAPPLICABLE_CANDIDATE!>++MismatchingArities1[0]<!>
+    <!INAPPLICABLE_CANDIDATE!>MismatchingArities1[0]++<!>
+    MismatchingArities1[0] += 1
+
+    <!UNRESOLVED_REFERENCE!>++<!><!INAPPLICABLE_CANDIDATE!>MismatchingArities2[0]<!>
+    <!INAPPLICABLE_CANDIDATE!>MismatchingArities2[0]<!><!UNRESOLVED_REFERENCE!>++<!>
+    MismatchingArities2[0] += 1
+}
+
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/IteratorAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/IteratorAmbiguity.fir.kt
new file mode 100644
index 00000000000..f709915a9d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/IteratorAmbiguity.fir.kt
@@ -0,0 +1,27 @@
+//KT-1821 Write test for ITERATOR_AMBIGUITY diagnostic
+
+interface MyCollectionInterface {
+}
+
+interface MyAnotherCollectionInterface {
+}
+
+class MyCollection : MyCollectionInterface, MyAnotherCollectionInterface {
+}
+
+fun MyCollectionInterface.iterator() = MyIterator()
+
+fun MyAnotherCollectionInterface.iterator() = MyIterator()
+
+class MyIterator {
+    fun next() : MyElement = MyElement()
+    fun hasNext() = true
+}
+
+class MyElement
+
+fun test1(collection: MyCollection) {
+    collection.<!AMBIGUITY!>iterator<!>()
+    <!AMBIGUITY, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (element in collection) {
+    }<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/assignmentOperationsCheckReturnType.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/assignmentOperationsCheckReturnType.fir.kt
new file mode 100644
index 00000000000..67a60bb81f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/assignmentOperationsCheckReturnType.fir.kt
@@ -0,0 +1,48 @@
+fun intBinEq() {
+    var x = 0
+    <!UNRESOLVED_REFERENCE!>x += 'a'<!>
+    x += 1.toByte()
+    x += 1.toShort()
+    x += 1L
+    <!UNRESOLVED_REFERENCE!>x += 1f<!>
+    <!UNRESOLVED_REFERENCE!>x += 1.0<!>
+    <!UNRESOLVED_REFERENCE!>x *= 'a'<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1.toByte()<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1.toShort()<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1L<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1f<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1.0<!>
+}
+
+fun shortBinEq() {
+    var x = 0.toShort()
+    <!UNRESOLVED_REFERENCE!>x += 'a'<!>
+    x += 1.toByte()
+    <!UNRESOLVED_REFERENCE!>x += 1.toShort()<!>
+    <!UNRESOLVED_REFERENCE!>x += 1L<!>
+    <!UNRESOLVED_REFERENCE!>x += 1f<!>
+    <!UNRESOLVED_REFERENCE!>x += 1.0<!>
+
+    <!UNRESOLVED_REFERENCE!>x *= 'a'<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1.toByte()<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1.toShort()<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1L<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1f<!>
+    <!UNRESOLVED_REFERENCE!>x *= 1.0<!>
+}
+
+class A {
+    operator fun plus(x : A) : A { return x }
+}
+
+class B {
+    operator fun plus(x : A) : A { return x }
+}
+
+fun overloading() {
+    var x = A()
+    var y = A()
+    x += y
+    var z = B()
+    z += x
+}
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/compareToNullable.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/compareToNullable.fir.kt
new file mode 100644
index 00000000000..a400f76638a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/compareToNullable.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    operator fun compareTo(c: C): Int? = null
+}
+
+fun test(c: C) {
+    c < c
+    c <= c
+    c >= c
+    c > c
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/kt1028.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/kt1028.fir.kt
new file mode 100644
index 00000000000..b4e43ca6326
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/kt1028.fir.kt
@@ -0,0 +1,35 @@
+//KT-1028 Wrong type checking for plusAssign
+package kt1028
+
+import java.util.*
+
+class event<T>()
+{
+    val callbacks = ArrayList< Function1<T, Unit> >() // Should be ArrayList<()->Unit>, bug posted
+
+    operator fun plusAssign(f : (T) -> Unit) = callbacks.add(f)
+    operator fun minusAssign(f : (T) -> Unit) = callbacks.remove(f)
+    fun call(value : T) { for(c in callbacks) c(value) }
+}
+
+class MouseMovedEventArgs()
+{
+    public val X : Int = 0
+}
+
+class Control()
+{
+    public val MouseMoved : event<MouseMovedEventArgs> = event<MouseMovedEventArgs>()
+
+    fun MoveMouse() = MouseMoved.call(MouseMovedEventArgs())
+}
+
+class Test()
+{
+    fun test()
+    {
+        val control = Control()
+        control.MouseMoved += { <!UNRESOLVED_REFERENCE!>it<!>.<!UNRESOLVED_REFERENCE!>X<!> } // here
+        control.MouseMoved.plusAssign( { it.X } ) // ok
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/kt11300.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/kt11300.fir.kt
new file mode 100644
index 00000000000..9542129f87d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/kt11300.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+
+class A {
+    operator fun get(x: Int): Int = x
+    fun set(x: Int, y: Int) {} // no `operator` modifier
+}
+
+fun main() {
+    val a = A()
+    a[1]++
+    a[1] += 3
+    a[1] = a[1] + 3
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/kt13330.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/kt13330.fir.kt
new file mode 100644
index 00000000000..f811d50b9f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/kt13330.fir.kt
@@ -0,0 +1,4 @@
+// !WITH_NEW_INFERENCE
+//KT-13330 AssertionError: Illegal resolved call to variable with invoke
+
+fun foo(exec: (String.() -> Unit)?) = "".<!UNRESOLVED_REFERENCE!>exec<!><caret>() // <caret> is test data tag here
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/kt13349.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/kt13349.fir.kt
new file mode 100644
index 00000000000..b3c73e430df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/kt13349.fir.kt
@@ -0,0 +1,7 @@
+object Foo {
+    operator fun <T> invoke() {}
+}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>Foo<!><Int>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/kt3450.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/kt3450.fir.kt
new file mode 100644
index 00000000000..3f5d1e27f07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/kt3450.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+public class A {
+    public operator fun get(vararg attrs : Pair<String, String>) : A = this
+}
+operator fun String.unaryPlus() : A = A()
+operator fun A.div(s : String) : A = A()
+
+fun test() {
+    (+"node2" / "node3" / "zzz") ["attr" to "value", "a2" to "v2"]
+}
+
+//---------
+class B {
+    public operator fun get(s : String, q : String) : B = this
+    public operator fun get(s : Pair<String, String>) : B = this
+    public operator fun invoke(q : B.() -> Unit) : B = this
+}
+val x = B()["a", "v"]["a" to "b"] {} ["q" to "p"] // does not parses around {}
+
+//from library
+data class Pair<out A, out B> (val first: A, val second: B)
+infix fun <A,B> A.to(that: B) = Pair(this, that)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnArray.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnArray.fir.kt
new file mode 100644
index 00000000000..532bba2f335
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnArray.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    operator fun get(i: Int): C = this
+}
+
+operator fun C.plus(a: Any): C = this
+operator fun C.plusAssign(a: Any) {}
+
+class C1 {
+    operator fun get(i: Int): C = C()
+    operator fun set(i: Int, v: C) {}
+}
+
+fun test() {
+    val c = C()
+    c[0] += ""
+    var c1 = C1()
+    c1[0] += ""
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnLocal.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnLocal.fir.kt
new file mode 100644
index 00000000000..4063b709120
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnLocal.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C
+
+operator fun C.plus(a: Any): C = this
+operator fun C.plusAssign(a: Any) {}
+
+fun test() {
+    val c = C()
+    c += ""
+    var c1 = C()
+    <!ASSIGN_OPERATOR_AMBIGUITY!>c1 += ""<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnProperty.fir.kt b/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnProperty.fir.kt
new file mode 100644
index 00000000000..fc1bb6297da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/operatorsOverloading/plusAssignOnProperty.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class C {
+    val c: C = C()
+}
+
+operator fun C.plus(a: Any): C = this
+operator fun C.plusAssign(a: Any) {}
+
+class C1 {
+    var c: C = C()
+}
+
+fun test() {
+    val c = C()
+    c.c += ""
+    var c1 = C1()
+    <!ASSIGN_OPERATOR_AMBIGUITY!>c1.c += ""<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOlverloadsGenericFunctions.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOlverloadsGenericFunctions.fir.kt
new file mode 100644
index 00000000000..e54843f0cc3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOlverloadsGenericFunctions.fir.kt
@@ -0,0 +1,34 @@
+fun <T1> test1(x: List<T1>) = x
+fun <T2> test1(x: List<T2>) = x
+
+fun <T1> List<T1>.test1a() {}
+fun <T2> List<T2>.test1a() {}
+
+fun <T> test2(x: List<T>) = x
+fun test2(x: List<String>) = x
+
+fun <T> List<T>.test2a() {}
+fun List<String>.test2a() {}
+
+fun <T : Any> test3(x: List<T>) = x
+fun test3(x: List<Any>) = x
+
+fun <T : Any> List<T>.test3a() {}
+fun List<Any>.test3a() {}
+
+fun <T> test4(x: Map<T, T>) = x
+fun <K, V> test4(x: Map<K, V>) = x
+
+fun <T> Map<T, T>.test4a() {}
+fun <K, V> Map<K, V>.test4a() {}
+
+class Inv<T>
+
+fun <T> test5(x: Inv<T>) = x
+fun <T> test5(x: Inv<out T>) = x
+
+fun <T> test6(x: Array<T>) = x
+fun test6(x: Array<String>) = x
+
+fun <T> test7(x: Inv<T>) = x
+fun <T> Inv<T>.test7() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsFunsDifferentReturnInClass.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsFunsDifferentReturnInClass.fir.kt
new file mode 100644
index 00000000000..e2f8356240f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsFunsDifferentReturnInClass.fir.kt
@@ -0,0 +1,6 @@
+class A {
+    fun a(a: Int): Int = 0
+
+    fun a(a: Int) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsFunsDifferentReturnInPackage.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsFunsDifferentReturnInPackage.fir.kt
new file mode 100644
index 00000000000..9eb073bf03a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsFunsDifferentReturnInPackage.fir.kt
@@ -0,0 +1,7 @@
+package qwertyuiop
+
+fun c(s: String) {
+}
+
+fun c(s: String) {
+}
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalExtFunsInPackage.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalExtFunsInPackage.fir.kt
new file mode 100644
index 00000000000..559f0c9ab01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalExtFunsInPackage.fir.kt
@@ -0,0 +1,5 @@
+package extensionFunctions
+
+fun Int.qwe(a: Float) = 1
+
+fun Int.qwe(a: Float) = 2
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalFunsInClass.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalFunsInClass.fir.kt
new file mode 100644
index 00000000000..93a3bbb7069
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalFunsInClass.fir.kt
@@ -0,0 +1,7 @@
+class A() {
+    fun b() {
+    }
+
+    fun b() {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalFunsTPInClass.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalFunsTPInClass.fir.kt
new file mode 100644
index 00000000000..48213d13dd6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalFunsTPInClass.fir.kt
@@ -0,0 +1,4 @@
+class Aaa() {
+    fun f() = 1
+    fun <P> f() = 1
+}
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalValsInClass.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalValsInClass.fir.kt
new file mode 100644
index 00000000000..56352d941f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsIdenticalValsInClass.fir.kt
@@ -0,0 +1,4 @@
+class Aaa() {
+    val a = 1
+    val a = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsValsDifferentTypeInClass.fir.kt b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsValsDifferentTypeInClass.fir.kt
new file mode 100644
index 00000000000..da5d63eba02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConflictingOverloadsValsDifferentTypeInClass.fir.kt
@@ -0,0 +1,4 @@
+class Aaa() {
+    val a = 1
+    val a = ""
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/ConstructorVsFunOverload.fir.kt b/compiler/testData/diagnostics/tests/overload/ConstructorVsFunOverload.fir.kt
new file mode 100644
index 00000000000..24e7c934b48
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ConstructorVsFunOverload.fir.kt
@@ -0,0 +1,29 @@
+// constructor vs. fun overload
+
+package constructorVsFun
+
+class a() { }
+
+fun a() = 1
+
+class Tram {
+    fun f() { }
+
+    class f() { }
+}
+
+class Yvayva {
+    companion object {
+        fun fghj() { }
+
+        class fghj() { }
+    }
+}
+
+class Rtyu {
+    fun ololo() { }
+
+    companion object {
+        class ololo() { }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/EmptyArgumentListInLambda.fir.kt b/compiler/testData/diagnostics/tests/overload/EmptyArgumentListInLambda.fir.kt
new file mode 100644
index 00000000000..c7967cb0894
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/EmptyArgumentListInLambda.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(g: () -> Int) {}
+fun foo(f: (Int) -> Int) {}
+
+fun test() {
+    <!AMBIGUITY!>foo<!> { -> 42 }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/ExtFunDifferentReceiver.fir.kt b/compiler/testData/diagnostics/tests/overload/ExtFunDifferentReceiver.fir.kt
new file mode 100644
index 00000000000..066ad1f50a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/ExtFunDifferentReceiver.fir.kt
@@ -0,0 +1,3 @@
+fun Int.rty() = 3
+
+fun String.rty() = 4
diff --git a/compiler/testData/diagnostics/tests/overload/FunNoConflictInDifferentPackages.fir.kt b/compiler/testData/diagnostics/tests/overload/FunNoConflictInDifferentPackages.fir.kt
new file mode 100644
index 00000000000..7ef2f1c5738
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/FunNoConflictInDifferentPackages.fir.kt
@@ -0,0 +1,13 @@
+// FILE: pkg1.kt
+// check no error in overload in different packages
+
+package pkg1
+fun e() = 1
+
+// FILE: pkg2.kt
+package pkg2
+fun e() = 1
+
+// FILE: pkg3pkg1.kt
+package pkg3.pkg1
+fun e() = 1
diff --git a/compiler/testData/diagnostics/tests/overload/LocalFunctions.fir.kt b/compiler/testData/diagnostics/tests/overload/LocalFunctions.fir.kt
new file mode 100644
index 00000000000..1e9a89bbffd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/LocalFunctions.fir.kt
@@ -0,0 +1,213 @@
+fun test() {
+    fun test1() {}
+    fun test1() {}
+
+    fun Any.test2() {}
+    fun test2(x: Any) = x
+
+    fun Any.test3() {}
+    fun Any.test3() {}
+
+    fun test4(): Int = 0
+    fun test4(): String = ""
+
+    class Test5(val x: Int) {
+        constructor(): this(0)
+    }
+    fun Test5() {}
+    fun Test5(x: Int) = x
+
+    fun local() {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+    }
+}
+
+class Test {
+    init {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+    }
+
+    fun test() {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+    }
+
+    val property: Any get() {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+
+        return 0
+    }
+}
+
+val property: Any get() {
+    fun test1() {}
+    fun test1() {}
+
+    fun Any.test2() {}
+    fun test2(x: Any) = x
+
+    fun Any.test3() {}
+    fun Any.test3() {}
+
+    fun test4(): Int = 0
+    fun test4(): String = ""
+
+    class Test5(val x: Int) {
+        constructor(): this(0)
+    }
+    fun Test5() {}
+    fun Test5(x: Int) = x
+
+    return 0
+}
+
+object Object {
+    fun test() {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+    }
+
+    val property: Any get() {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+
+        return 0
+    }
+}
+
+val obj = object {
+    fun test() {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+    }
+
+    val property: Any get() {
+        fun test1() {}
+        fun test1() {}
+
+        fun Any.test2() {}
+        fun test2(x: Any) = x
+
+        fun Any.test3() {}
+        fun Any.test3() {}
+
+        fun test4(): Int = 0
+        fun test4(): String = ""
+
+        class Test5(val x: Int) {
+            constructor(): this(0)
+        }
+        fun Test5() {}
+        fun Test5(x: Int) = x
+
+        return 0
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/OverloadFunRegularAndExt.fir.kt b/compiler/testData/diagnostics/tests/overload/OverloadFunRegularAndExt.fir.kt
new file mode 100644
index 00000000000..34c84965174
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/OverloadFunRegularAndExt.fir.kt
@@ -0,0 +1,7 @@
+// check no error when regular function and extension function have same name
+
+package extensionAndRegular
+
+fun who() = 1
+
+fun Int.who() = 1
diff --git a/compiler/testData/diagnostics/tests/overload/OverloadVarAndFunInClass.fir.kt b/compiler/testData/diagnostics/tests/overload/OverloadVarAndFunInClass.fir.kt
new file mode 100644
index 00000000000..201a1193c06
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/OverloadVarAndFunInClass.fir.kt
@@ -0,0 +1,4 @@
+class Aaaa() {
+    val bb = 1
+    fun bb() = 1
+}
diff --git a/compiler/testData/diagnostics/tests/overload/SyntheticAndNotSynthetic.fir.kt b/compiler/testData/diagnostics/tests/overload/SyntheticAndNotSynthetic.fir.kt
new file mode 100644
index 00000000000..0fbe04eebe7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/SyntheticAndNotSynthetic.fir.kt
@@ -0,0 +1,7 @@
+fun Runnable(f: () -> Unit): Runnable = object : Runnable {
+    public override fun run() {
+        f()
+    }
+}
+
+val x = Runnable {  }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/TypeParameterMultipleBounds.fir.kt b/compiler/testData/diagnostics/tests/overload/TypeParameterMultipleBounds.fir.kt
new file mode 100644
index 00000000000..55e95f4bc38
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/TypeParameterMultipleBounds.fir.kt
@@ -0,0 +1,15 @@
+import java.io.Serializable
+
+interface Test1 {
+    fun <T> foo(t: T) where T : Cloneable, T : Serializable
+    fun <T> foo(t: T) where T : Serializable, T : Cloneable
+}
+
+
+interface I1
+interface I2 : I1
+
+interface Test2 {
+    fun <T> foo(t: T) where T : I1, T : I2
+    fun <T> foo(t: T) where T : I2, T : I1
+}
diff --git a/compiler/testData/diagnostics/tests/overload/UnsubstitutedJavaGenetics.fir.kt b/compiler/testData/diagnostics/tests/overload/UnsubstitutedJavaGenetics.fir.kt
new file mode 100644
index 00000000000..9615bb55a6b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/UnsubstitutedJavaGenetics.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// FILE: Base.java
+public interface Base {
+    <T> String foo(T a);
+    <T> int foo(T a, Object... args);
+}
+
+// FILE: Derived.java
+public interface Derived extends Base {
+}
+
+// FILE: test.kt
+fun testDerived(base: Base, derived: Derived) {
+    val test1: String = base.foo("")
+    val test2: String = derived.foo("")
+}
diff --git a/compiler/testData/diagnostics/tests/overload/defaultParameters.fir.kt b/compiler/testData/diagnostics/tests/overload/defaultParameters.fir.kt
new file mode 100644
index 00000000000..1a28b795288
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/defaultParameters.fir.kt
@@ -0,0 +1,59 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+fun simple() = 1
+fun simple(a: Int = 3) = ""
+
+fun twoDefault(a: Int = 2) = 1
+fun twoDefault(a: Any = 2, b: String = "") = ""
+
+fun <T> withGeneric(a: T) = 1
+fun <T> withGeneric(a: T, b: Int = 4) = ""
+
+fun <T> discriminateGeneric(a: T) = 1
+fun discriminateGeneric(a: Int, b: String = "") = ""
+
+fun <T: CharSequence> withDefaultGeneric(t: T, d: T? = null) = 1
+fun <T: Any> withDefaultGeneric(t: T, d: T? = null, a: Int = 1) = ""
+
+fun withDefaults(a: Any = 2) = 1
+fun withDefaults(a: Int = 2, b: String = "") = ""
+
+fun <T: Any> withGenericDefaults(t: T, d: T? = null) = 1
+fun <T: CharSequence> withGenericDefaults(t: T, d: T? = null, a: Int = 1) = ""
+
+fun wrong(a: Int = 1) {}
+fun wrong(a: String = "", b: Int = 1) {}
+
+fun test() {
+    val a = simple()
+    a checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    val b = simple(1)
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    val c = twoDefault()
+    c checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    val d = twoDefault(1)
+    d checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    val e = twoDefault(1, "")
+    e checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    val f = withGeneric(3)
+    f checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    val g = discriminateGeneric(1)
+    g checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    val h = withDefaultGeneric("")
+    h checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    withDefaults(1)
+
+    withGenericDefaults("")
+
+    <!AMBIGUITY!>wrong<!>(null!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/kt10939.fir.kt b/compiler/testData/diagnostics/tests/overload/kt10939.fir.kt
new file mode 100644
index 00000000000..1aca3d7749a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/kt10939.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+object X1
+object X2
+
+interface Base {
+    fun <T1> foo(a: T1): X1
+    fun <T2> foo(a: T2, vararg args: Any): X2
+}
+
+interface Derived : Base
+
+fun testDerived(base: Base, derived: Derived) {
+    val test1: X1 = base.foo("")
+    val test2: X1 = derived.foo("")
+}
+
+interface GenericBase<T> {
+    fun <T1> foo(x: T, a: T1): X1
+}
+
+interface SpecializedDerived : GenericBase<String> {
+    fun <T2> foo(x: String, a: T2, vararg args: Any): X2
+}
+
+fun testSpecializedDerived(derived: SpecializedDerived) {
+    val test1: X1 = derived.foo("", "")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/kt1998.fir.kt b/compiler/testData/diagnostics/tests/overload/kt1998.fir.kt
new file mode 100644
index 00000000000..56e521a67e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/kt1998.fir.kt
@@ -0,0 +1,14 @@
+// KT-1998 Strange "Overload resolution ambiguity"
+
+object A {
+    val c : String = "test"
+
+    fun f(b: B): String {
+        return b.c // Test no "Overload resolution ambiguity" is reported here
+    }
+}
+
+class B
+
+val B.c : String
+    get() = "test"
diff --git a/compiler/testData/diagnostics/tests/overload/kt2493.fir.kt b/compiler/testData/diagnostics/tests/overload/kt2493.fir.kt
new file mode 100644
index 00000000000..ccde55d8321
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/kt2493.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+interface A
+interface B
+
+fun <R: A> R.f() {
+}
+
+fun <R: B> R.f() {
+}
+
+class AImpl: A
+class BImpl: B
+
+class C: A, B
+
+fun main() {
+    AImpl().f()
+    BImpl().f()
+    C().<!AMBIGUITY!>f<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/kt7068.fir.kt b/compiler/testData/diagnostics/tests/overload/kt7068.fir.kt
new file mode 100644
index 00000000000..cc337d40b11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/kt7068.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun withLambda(block : Int.(String) -> Unit) {
+}
+
+fun withLambda(o : Int, block : Int.(String) -> Unit) {
+}
+
+fun test() {
+    withLambda {
+        it.length
+    }
+
+    withLambda { r -> // no error should be here
+        r.length
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/kt7068_2.fir.kt b/compiler/testData/diagnostics/tests/overload/kt7068_2.fir.kt
new file mode 100644
index 00000000000..d038ee2264f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/kt7068_2.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun withLambda(block : Int.(String) -> Unit) {
+}
+
+fun withLambda(block : Int.(String, String) -> Unit) {
+}
+
+fun test() {
+    withLambda { r ->
+        r.length
+    }
+
+    withLambda { x, y ->
+        x.length + y.length
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/kt7440.fir.kt b/compiler/testData/diagnostics/tests/overload/kt7440.fir.kt
new file mode 100644
index 00000000000..afc5a210323
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/kt7440.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER
+// KT-7440 Cannot complete type inference if two extension functions for interface hierarchy
+
+package inferenceagain
+
+interface Base<T>
+interface Derived<T> : Base<T>
+
+fun <R : Comparable<R>, T : Any> Base<T>.maxBy(f: (T) -> R): T? = null
+fun <R : Comparable<R>, T : Any> Derived<T>.maxBy(f: (T) -> R): T? = null
+
+fun <T> derivedOf(vararg members: T): Derived<T> = null!!
+
+fun <T> x(l: Derived<T>) {
+    derivedOf(1, 2, 3).maxBy<Int, Int> { it  } // works
+    derivedOf(1, 2, 3).maxBy { it } // should work
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/overload/onlyPrivateOverloadsDiagnostic.fir.kt b/compiler/testData/diagnostics/tests/overload/onlyPrivateOverloadsDiagnostic.fir.kt
new file mode 100644
index 00000000000..13028da997e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/overload/onlyPrivateOverloadsDiagnostic.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A {
+    private fun foo(i: Int) {}
+    private fun foo(s: String) {}
+}
+
+fun test(a: A) {
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>(3)
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+}
+
diff --git a/compiler/testData/diagnostics/tests/override/AbstractFunImplemented.fir.kt b/compiler/testData/diagnostics/tests/override/AbstractFunImplemented.fir.kt
new file mode 100644
index 00000000000..ef6b6fa41b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/AbstractFunImplemented.fir.kt
@@ -0,0 +1,7 @@
+abstract class A {
+    abstract fun foo(): Int
+}
+
+class B() : A() {
+    override fun foo() = 1
+}
diff --git a/compiler/testData/diagnostics/tests/override/AbstractFunNotImplemented.fir.kt b/compiler/testData/diagnostics/tests/override/AbstractFunNotImplemented.fir.kt
new file mode 100644
index 00000000000..1059e1aae84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/AbstractFunNotImplemented.fir.kt
@@ -0,0 +1,6 @@
+abstract class A {
+    abstract fun foo(): Int
+}
+
+class B() : A() {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/AbstractValImplemented.fir.kt b/compiler/testData/diagnostics/tests/override/AbstractValImplemented.fir.kt
new file mode 100644
index 00000000000..a9669a69142
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/AbstractValImplemented.fir.kt
@@ -0,0 +1,7 @@
+abstract class A {
+    abstract val i: Int
+}
+
+class B() : A() {
+    override val i = 1
+}
diff --git a/compiler/testData/diagnostics/tests/override/AbstractValNotImplemented.fir.kt b/compiler/testData/diagnostics/tests/override/AbstractValNotImplemented.fir.kt
new file mode 100644
index 00000000000..813af28f460
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/AbstractValNotImplemented.fir.kt
@@ -0,0 +1,6 @@
+abstract class A {
+    abstract val i: Int
+}
+
+class B() : A() {
+}
diff --git a/compiler/testData/diagnostics/tests/override/AbstractVarImplemented.fir.kt b/compiler/testData/diagnostics/tests/override/AbstractVarImplemented.fir.kt
new file mode 100644
index 00000000000..b0c3055b5fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/AbstractVarImplemented.fir.kt
@@ -0,0 +1,7 @@
+abstract class A {
+    abstract var i: Int
+}
+
+class B() : A() {
+    override var i = 1
+}
diff --git a/compiler/testData/diagnostics/tests/override/AbstractVarNotImplemented.fir.kt b/compiler/testData/diagnostics/tests/override/AbstractVarNotImplemented.fir.kt
new file mode 100644
index 00000000000..27305d3b2fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/AbstractVarNotImplemented.fir.kt
@@ -0,0 +1,6 @@
+abstract class A {
+    abstract var i: Int
+}
+
+class B() : A() {
+}
diff --git a/compiler/testData/diagnostics/tests/override/AllPrivateFromSuperTypes.fir.kt b/compiler/testData/diagnostics/tests/override/AllPrivateFromSuperTypes.fir.kt
new file mode 100644
index 00000000000..4a6d96de823
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/AllPrivateFromSuperTypes.fir.kt
@@ -0,0 +1,14 @@
+package test
+
+interface A {
+    private val a: String
+      get() = "AAAA!"
+}
+
+open class C {
+    private val a: String = ""
+}
+
+class Subject : C(), A {
+    val c = <!INAPPLICABLE_CANDIDATE!>a<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/ComplexValRedeclaration.fir.kt b/compiler/testData/diagnostics/tests/override/ComplexValRedeclaration.fir.kt
new file mode 100644
index 00000000000..c9f056a1d6d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ComplexValRedeclaration.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER
+package override.generics
+
+abstract class MyAbstractClass<T> {
+    abstract val pr : T
+}
+
+abstract class MyLegalAbstractClass2<T>(t : T) : MyAbstractClass<Int>() {
+    val <R> pr : T = t
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/ConflictingFunctionSignatureFromSuperclass.fir.kt b/compiler/testData/diagnostics/tests/override/ConflictingFunctionSignatureFromSuperclass.fir.kt
new file mode 100644
index 00000000000..a4e1448448d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ConflictingFunctionSignatureFromSuperclass.fir.kt
@@ -0,0 +1,7 @@
+open class Aaa() {
+    fun foo() = 1
+}
+
+open class Bbb() : Aaa() {
+    fun <T> foo() = 2
+}
diff --git a/compiler/testData/diagnostics/tests/override/ConflictingPropertySignatureFromSuperclass.fir.kt b/compiler/testData/diagnostics/tests/override/ConflictingPropertySignatureFromSuperclass.fir.kt
new file mode 100644
index 00000000000..9b2d5ffd2a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ConflictingPropertySignatureFromSuperclass.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER
+open class Aaa() {
+    val bar = 1
+}
+
+open class Bbb() : Aaa() {
+    val <T> bar = "aa"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/DefaultParameterValueInOverride.fir.kt b/compiler/testData/diagnostics/tests/override/DefaultParameterValueInOverride.fir.kt
new file mode 100644
index 00000000000..ddae0ca41b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/DefaultParameterValueInOverride.fir.kt
@@ -0,0 +1,13 @@
+open class A {
+    open fun foo(a : Int) {}
+}
+
+class C : A() {
+    override fun foo(a : Int = 1) {
+    }
+}
+
+class D : A() {
+    override fun foo(a : Int = 1) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/override/DefaultParameterValues-NoErrorsWhenInheritingFromOneTypeTwice.fir.kt b/compiler/testData/diagnostics/tests/override/DefaultParameterValues-NoErrorsWhenInheritingFromOneTypeTwice.fir.kt
new file mode 100644
index 00000000000..a27d78224ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/DefaultParameterValues-NoErrorsWhenInheritingFromOneTypeTwice.fir.kt
@@ -0,0 +1,15 @@
+interface Y {
+    fun foo(a : Int = 1)
+}
+
+interface YSub : Y {
+
+}
+
+class Z2 : Y, YSub {
+    override fun foo(a : Int) {}
+}
+
+object Z2O : Y, YSub {
+    override fun foo(a : Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/Delegation.fir.kt b/compiler/testData/diagnostics/tests/override/Delegation.fir.kt
new file mode 100644
index 00000000000..f4820e64c54
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/Delegation.fir.kt
@@ -0,0 +1,49 @@
+package test
+
+interface X {
+    fun foo(): String? {
+        return null
+    }
+}
+
+interface Y {
+    fun foo(): String {
+        return "foo"
+    }
+}
+
+interface Incompatible {
+    fun foo(): Int {
+        return 3
+    }
+}
+
+class Test1(val x: X) : X by x, Y {
+    override fun foo(): String? {
+        return null
+    }
+}
+
+class Test2(val x: X) : X by x, Y {
+    override fun foo(): String {
+        return "foo"
+    }
+}
+
+class Test3(val y: Y) : X, Y by y {
+    override fun foo(): String? {
+        return null
+    }
+}
+
+class Test4(val y: Y) : X, Y by y {
+    override fun foo(): String {
+        return "foo"
+    }
+}
+
+class Test5(val y: Y, val x: X) : X by x, Y by y, Incompatible {
+    override fun foo(): Int {
+        return 3
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/DelegationFun.fir.kt b/compiler/testData/diagnostics/tests/override/DelegationFun.fir.kt
new file mode 100644
index 00000000000..b7ff2c55ef7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/DelegationFun.fir.kt
@@ -0,0 +1,7 @@
+package delegation
+
+interface Aaa {
+    fun foo()
+}
+
+class Bbb(aaa: Aaa) : Aaa by aaa
diff --git a/compiler/testData/diagnostics/tests/override/DelegationVal.fir.kt b/compiler/testData/diagnostics/tests/override/DelegationVal.fir.kt
new file mode 100644
index 00000000000..7f7a506b5b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/DelegationVal.fir.kt
@@ -0,0 +1,7 @@
+package delegation
+
+interface Aaa {
+    val i: Int
+}
+
+class Bbb(aaa: Aaa) : Aaa by aaa
diff --git a/compiler/testData/diagnostics/tests/override/DelegationVar.fir.kt b/compiler/testData/diagnostics/tests/override/DelegationVar.fir.kt
new file mode 100644
index 00000000000..4c9a70763c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/DelegationVar.fir.kt
@@ -0,0 +1,7 @@
+package delegation
+
+interface Aaa {
+    var i: Int
+}
+
+class Bbb(aaa: Aaa) : Aaa by aaa
diff --git a/compiler/testData/diagnostics/tests/override/DuplicateMethod.fir.kt b/compiler/testData/diagnostics/tests/override/DuplicateMethod.fir.kt
new file mode 100644
index 00000000000..3a5b3e7b8e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/DuplicateMethod.fir.kt
@@ -0,0 +1,8 @@
+interface Some {
+    fun test()
+}
+
+class SomeImpl : Some  {
+    override fun test() {}
+    override fun test() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/EqualityOfIntersectionTypes.fir.kt b/compiler/testData/diagnostics/tests/override/EqualityOfIntersectionTypes.fir.kt
new file mode 100644
index 00000000000..fc35e955bac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/EqualityOfIntersectionTypes.fir.kt
@@ -0,0 +1,15 @@
+interface Foo
+interface Bar
+
+interface A {
+    fun <T> foo()
+    where T : Foo, T : Bar
+    = Unit
+}
+
+class B : A {
+    override fun <T> foo()
+    where T : Foo, T : Bar
+    = Unit
+
+}
diff --git a/compiler/testData/diagnostics/tests/override/ExtendFunctionClass.fir.kt b/compiler/testData/diagnostics/tests/override/ExtendFunctionClass.fir.kt
new file mode 100644
index 00000000000..9a56a456d57
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ExtendFunctionClass.fir.kt
@@ -0,0 +1,9 @@
+package extendFunctionClass
+
+class A : Function1<Int, Int> {
+
+}
+
+class B : Function1<Int, Int> {
+    override fun invoke(p1 : Int) = p1
+}
diff --git a/compiler/testData/diagnostics/tests/override/FakeOverrideAbstractAndNonAbstractFun.fir.kt b/compiler/testData/diagnostics/tests/override/FakeOverrideAbstractAndNonAbstractFun.fir.kt
new file mode 100644
index 00000000000..7c8c385152a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/FakeOverrideAbstractAndNonAbstractFun.fir.kt
@@ -0,0 +1,9 @@
+open class Ccc() {
+    fun foo() = 1
+}
+
+interface Ttt {
+    fun foo(): Int
+}
+
+class Zzz() : Ccc(), Ttt
diff --git a/compiler/testData/diagnostics/tests/override/FakeOverrideDifferentDeclarationSignatures.fir.kt b/compiler/testData/diagnostics/tests/override/FakeOverrideDifferentDeclarationSignatures.fir.kt
new file mode 100644
index 00000000000..35f3a9059b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/FakeOverrideDifferentDeclarationSignatures.fir.kt
@@ -0,0 +1,11 @@
+interface A {
+    fun f(): String = "string"
+}
+
+open class B {
+    open fun f(): CharSequence = "charSequence"
+}
+
+class C : B(), A
+
+val obj: A = object : B(), A {}
diff --git a/compiler/testData/diagnostics/tests/override/FakeOverrideModality1.fir.kt b/compiler/testData/diagnostics/tests/override/FakeOverrideModality1.fir.kt
new file mode 100644
index 00000000000..370dee14575
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/FakeOverrideModality1.fir.kt
@@ -0,0 +1,14 @@
+interface A {
+    fun foo() {}
+}
+
+interface B : A {
+    abstract override fun foo()
+}
+
+interface C {
+    abstract fun foo()
+}
+
+// Fake override Z#foo should be abstract
+class Z : B, C
diff --git a/compiler/testData/diagnostics/tests/override/FakeOverrideModality2.fir.kt b/compiler/testData/diagnostics/tests/override/FakeOverrideModality2.fir.kt
new file mode 100644
index 00000000000..3b5f283db50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/FakeOverrideModality2.fir.kt
@@ -0,0 +1,18 @@
+interface A {
+    fun foo() {}
+}
+
+interface B : A {
+    abstract override fun foo()
+}
+
+interface C : A {
+    abstract override fun foo()
+}
+
+interface D : A {
+    override fun foo() = super.foo()
+}
+
+// Fake override Z#foo should be open
+class Z : B, C, D
diff --git a/compiler/testData/diagnostics/tests/override/FakeOverrideModality3.fir.kt b/compiler/testData/diagnostics/tests/override/FakeOverrideModality3.fir.kt
new file mode 100644
index 00000000000..022cd3bd460
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/FakeOverrideModality3.fir.kt
@@ -0,0 +1,16 @@
+interface A {
+    fun foo() {}
+}
+
+interface B : A {
+    abstract override fun foo()
+}
+
+interface C : A {
+    abstract override fun foo()
+}
+
+interface D : A
+
+// Fake override Z#foo should be abstract
+class Z : B, C, D
diff --git a/compiler/testData/diagnostics/tests/override/Generics.fir.kt b/compiler/testData/diagnostics/tests/override/Generics.fir.kt
new file mode 100644
index 00000000000..3f0d4bc44e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/Generics.fir.kt
@@ -0,0 +1,60 @@
+package override.generics
+
+interface MyTrait<T> {
+    fun foo(t: T) : T
+}
+
+abstract class MyAbstractClass<T> {
+    abstract fun bar(t: T) : T
+    abstract val pr : T
+}
+
+interface MyProps<T> {
+    val p : T
+}
+
+open class MyGenericClass<T>(t : T) : MyTrait<T>, MyAbstractClass<T>(), MyProps<T> {
+    override fun foo(t: T) = t
+    override fun bar(t: T) = t
+    override val p : T = t
+    override val pr : T = t
+}
+
+class MyChildClass() : MyGenericClass<Int>(1) {}
+class MyChildClass1<T>(t : T) : MyGenericClass<T>(t) {}
+class MyChildClass2<T>(t : T) : MyGenericClass<T>(t) {
+    fun foo(t: T) = t
+    val pr : T = t
+    override fun bar(t: T) = t
+    override val p : T = t
+}
+
+open class MyClass() : MyTrait<Int>, MyAbstractClass<String>() {
+    override fun foo(t: Int) = t
+    override fun bar(t: String) = t
+    override val pr : String = "1"
+}
+
+abstract class MyAbstractClass1 : MyTrait<Int>, MyAbstractClass<String>() {
+    override fun foo(t: Int) = t
+    override fun bar(t: String) = t
+}
+
+class MyIllegalGenericClass1<T> : MyTrait<T>, MyAbstractClass<T>() {}
+class MyIllegalGenericClass2<T, R>(r : R) : MyTrait<T>, MyAbstractClass<R>() {
+    override fun foo(r: R) = r
+    override val <T> pr : R = r
+}
+class MyIllegalClass1 : MyTrait<Int>, MyAbstractClass<String>() {}
+abstract class MyLegalAbstractClass1 : MyTrait<Int>, MyAbstractClass<String>() {}
+
+class MyIllegalClass2<T>(t : T) : MyTrait<Int>, MyAbstractClass<Int>() {
+    fun foo(t: T) = t
+    fun bar(t: T) = t
+    val <R> pr : T = t
+}
+abstract class MyLegalAbstractClass2<T>(t : T) : MyTrait<Int>, MyAbstractClass<Int>() {
+    fun foo(t: T) = t
+    fun bar(t: T) = t
+    val <R> pr : T = t
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/InvisiblePotentialOverride.fir.kt b/compiler/testData/diagnostics/tests/override/InvisiblePotentialOverride.fir.kt
new file mode 100644
index 00000000000..94867e7289b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/InvisiblePotentialOverride.fir.kt
@@ -0,0 +1,7 @@
+open class A {
+    private fun foo() : Int = 1
+}
+
+class B : A() {
+    fun foo() : String = ""
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/MissingDelegate.fir.kt b/compiler/testData/diagnostics/tests/override/MissingDelegate.fir.kt
new file mode 100644
index 00000000000..21889dbfe5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/MissingDelegate.fir.kt
@@ -0,0 +1,3 @@
+class C : Base1 by Base2(1) {
+  fun test() { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/MultipleDefaultParametersInSupertypes.fir.kt b/compiler/testData/diagnostics/tests/override/MultipleDefaultParametersInSupertypes.fir.kt
new file mode 100644
index 00000000000..4de8d35e241
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/MultipleDefaultParametersInSupertypes.fir.kt
@@ -0,0 +1,15 @@
+interface X {
+    fun foo(a : Int = 1)
+}
+
+interface Y {
+    fun foo(a : Int = 1)
+}
+
+class Z : X, Y {
+    override fun foo(a : Int) {}
+}
+
+object ZO : X, Y {
+    override fun foo(a : Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/MultipleDefaultParametersInSupertypesNoOverride.fir.kt b/compiler/testData/diagnostics/tests/override/MultipleDefaultParametersInSupertypesNoOverride.fir.kt
new file mode 100644
index 00000000000..e00f26b093a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/MultipleDefaultParametersInSupertypesNoOverride.fir.kt
@@ -0,0 +1,15 @@
+interface X {
+    fun foo(a : Int = 1)
+}
+
+interface Y {
+    fun foo(a : Int = 1)
+}
+
+class Z : X, Y {
+    fun foo(a : Int) {}
+}
+
+object ZO : X, Y {
+    fun foo(a : Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/MultipleDefaultsAndNamesInSupertypes.fir.kt b/compiler/testData/diagnostics/tests/override/MultipleDefaultsAndNamesInSupertypes.fir.kt
new file mode 100644
index 00000000000..5a99fa791e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/MultipleDefaultsAndNamesInSupertypes.fir.kt
@@ -0,0 +1,14 @@
+interface A {
+    fun foo(x: Int = 42): Int
+}
+
+open class B {
+    fun foo(x: Int = 239) = x
+}
+
+interface C {
+    fun foo(y: Int): Int
+}
+
+// TODO DIFFERENT_NAMES_FOR_THE_SAME_PARAMETER_IN_SUPERTYPES reported twice
+class Z : A, B(), C
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/MultipleDefaultsInSupertypesNoExplicitOverride.fir.kt b/compiler/testData/diagnostics/tests/override/MultipleDefaultsInSupertypesNoExplicitOverride.fir.kt
new file mode 100644
index 00000000000..bb84bf8ce14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/MultipleDefaultsInSupertypesNoExplicitOverride.fir.kt
@@ -0,0 +1,10 @@
+interface X {
+    fun foo(a : Int = 1)
+}
+
+interface Y {
+    fun foo(a : Int = 1)
+}
+
+class Z1 : X, Y {} // BUG
+object Z1O : X, Y {} // BUG
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/NonGenerics.fir.kt b/compiler/testData/diagnostics/tests/override/NonGenerics.fir.kt
new file mode 100644
index 00000000000..7d9430c7527
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/NonGenerics.fir.kt
@@ -0,0 +1,50 @@
+package override.normal
+
+interface MyTrait {
+    fun foo()
+    val pr : Unit
+}
+
+abstract class MyAbstractClass {
+    abstract fun bar()
+    abstract val prr : Unit
+
+}
+
+open class MyClass() : MyTrait, MyAbstractClass() {
+    override fun foo() {}
+    override fun bar() {}
+
+    override val pr : Unit = Unit
+    override val prr : Unit = Unit
+}
+
+class MyChildClass() : MyClass() {}
+
+class MyIllegalClass : MyTrait, MyAbstractClass() {}
+
+class MyIllegalClass2() : MyTrait, MyAbstractClass() {
+    override fun foo() {}
+    override val pr : Unit = Unit
+    override val prr : Unit = Unit
+}
+
+class MyIllegalClass3() : MyTrait, MyAbstractClass() {
+    override fun bar() {}
+    override val pr : Unit = Unit
+    override val prr : Unit = Unit
+}
+
+class MyIllegalClass4() : MyTrait, MyAbstractClass() {
+    fun foo() {}
+    val pr : Unit
+    override fun other() {}
+    override val otherPr : Int = 1
+}
+
+class MyChildClass1() : MyClass() {
+    fun foo() {}
+    val pr : Unit = Unit
+    override fun bar() {}
+    override val prr : Unit = Unit
+}
diff --git a/compiler/testData/diagnostics/tests/override/ObjectDelegationManyImpl.fir.kt b/compiler/testData/diagnostics/tests/override/ObjectDelegationManyImpl.fir.kt
new file mode 100644
index 00000000000..2dd58530d21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ObjectDelegationManyImpl.fir.kt
@@ -0,0 +1,13 @@
+interface D {
+    fun foo()
+}
+
+interface E {
+    fun foo() {}
+}
+
+object Impl : D, E {
+    override fun foo() {}
+}
+
+val obj: D = object : D by Impl, E by Impl {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/OverrideWithErrors.fir.kt b/compiler/testData/diagnostics/tests/override/OverrideWithErrors.fir.kt
new file mode 100644
index 00000000000..e492c6cfbeb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/OverrideWithErrors.fir.kt
@@ -0,0 +1,9 @@
+package test
+
+open class A {
+  open fun foo(a: E) {}
+}
+
+class B : A() {
+  override fun foo(a: E) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/OverridingFinalMember.fir.kt b/compiler/testData/diagnostics/tests/override/OverridingFinalMember.fir.kt
new file mode 100644
index 00000000000..95f20afd171
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/OverridingFinalMember.fir.kt
@@ -0,0 +1,7 @@
+open class A {
+    final fun foo() {}
+}
+
+class B : A() {
+    override fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/override/ParameterDefaultValues-DefaultValueFromOnlyOneSupertype.fir.kt b/compiler/testData/diagnostics/tests/override/ParameterDefaultValues-DefaultValueFromOnlyOneSupertype.fir.kt
new file mode 100644
index 00000000000..158db681970
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ParameterDefaultValues-DefaultValueFromOnlyOneSupertype.fir.kt
@@ -0,0 +1,11 @@
+interface X {
+    fun foo(a : Int = 1)
+}
+
+interface Y {
+    fun foo(a : Int)
+}
+
+class Z : X, Y {
+    override fun foo(a : Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/ParentInheritsManyImplementations.fir.kt b/compiler/testData/diagnostics/tests/override/ParentInheritsManyImplementations.fir.kt
new file mode 100644
index 00000000000..1a64254694c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ParentInheritsManyImplementations.fir.kt
@@ -0,0 +1,17 @@
+package d
+
+interface A {
+    fun foo() = 1
+}
+
+interface B {
+    fun foo() = 2
+}
+
+open class C : A, B {}
+
+interface E {
+    fun foo(): Int
+}
+
+class D : C() {}
diff --git a/compiler/testData/diagnostics/tests/override/PropertyInConstructor.fir.kt b/compiler/testData/diagnostics/tests/override/PropertyInConstructor.fir.kt
new file mode 100644
index 00000000000..409fbb14b2e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/PropertyInConstructor.fir.kt
@@ -0,0 +1,11 @@
+open class Base {
+    protected open val prot: Int = 1
+    internal open val int: Int = 1
+    public open val pub: Int = 1
+}
+
+class Child(
+    override val prot: Int,
+    override val int: Int,
+    override val pub: Int
+) : Base()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/ProtectedAndPrivateFromSupertypes.fir.kt b/compiler/testData/diagnostics/tests/override/ProtectedAndPrivateFromSupertypes.fir.kt
new file mode 100644
index 00000000000..13616922adb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ProtectedAndPrivateFromSupertypes.fir.kt
@@ -0,0 +1,17 @@
+package test
+
+interface A {
+    val a: String
+}
+
+interface B {
+    val a: String
+}
+
+open class C {
+    private val a: String = ""
+}
+
+class Subject : C(), A, B {
+    val c = a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/SuspiciousCase1.fir.kt b/compiler/testData/diagnostics/tests/override/SuspiciousCase1.fir.kt
new file mode 100644
index 00000000000..e80e4732343
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/SuspiciousCase1.fir.kt
@@ -0,0 +1,12 @@
+// NamedFunctionDescriptor.substitute substitutes "overrides"
+// this test checks it does it properly
+
+interface Foo<P> {
+    fun quux(p: P, q: Int = 17) : Int = 18
+}
+
+interface Bar<Q> : Foo<Q>
+
+abstract class Baz() : Bar<String>
+
+fun zz(b: Baz) = b.quux("a")
diff --git a/compiler/testData/diagnostics/tests/override/ToAbstractMembersFromSuper-kt1996.fir.kt b/compiler/testData/diagnostics/tests/override/ToAbstractMembersFromSuper-kt1996.fir.kt
new file mode 100644
index 00000000000..fcdda569a7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/ToAbstractMembersFromSuper-kt1996.fir.kt
@@ -0,0 +1,11 @@
+// http://youtrack.jetbrains.com/issue/KT-1996
+
+interface Foo {
+    fun foo(): Unit
+}
+
+interface Bar {
+    fun foo(): Unit
+}
+
+class Baz : Foo, Bar
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/covariantOverrides.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/covariantOverrides.fir.kt
new file mode 100644
index 00000000000..c0ac2b03bc0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/covariantOverrides.fir.kt
@@ -0,0 +1,37 @@
+interface IBase {
+    fun copy(): IBase
+}
+
+interface ILeft : IBase {
+    override fun copy(): ILeft
+}
+
+open class CLeft : ILeft {
+    override fun copy(): ILeft = CLeft()
+}
+
+interface IRight : IBase {
+    override fun copy(): IRight
+}
+
+interface IDerived : ILeft, IRight {
+    override fun copy(): IDerived
+}
+
+// Error: ILeft::copy and IRight::copy have unrelated return types
+class CDerivedInvalid1 : ILeft, IRight
+
+// Error: CLeft::copy and IRight::copy have unrelated return types
+class CDerivedInvalid2 : CLeft(), IRight
+
+// OK: CDerived1::copy overrides both ILeft::copy and IRight::copy
+class CDerived1 : ILeft, IRight {
+    override fun copy(): CDerived1 = CDerived1()
+}
+
+// Although ILeft::copy and IRight::copy return types are unrelated, IDerived::copy return type is the most specific of three.
+abstract class CDerived2 : ILeft, IRight, IDerived
+
+class CDerived2a : ILeft, IRight, IDerived {
+    override fun copy(): IDerived = CDerived2a()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnType.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnType.fir.kt
new file mode 100644
index 00000000000..1c27c283354
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnType.fir.kt
@@ -0,0 +1,27 @@
+// FILE: J.java
+public interface J {
+    String foo(); // String!
+}
+
+// FILE: K.kt
+interface K1 {
+    fun foo(): String
+}
+
+interface K2 {
+    fun foo(): String?
+}
+
+interface KDerived1a : K1, J
+
+interface KDerived1b : J, K1
+
+interface KDerived2a : K2, J
+
+interface KDerived2b : J, K2
+
+interface KDerived12a : K1, K2, J
+
+interface KDerived12b : K1, J, K2
+
+interface KDerived12c : J, K1, K2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnTypeIn.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnTypeIn.fir.kt
new file mode 100644
index 00000000000..0c0e63b2220
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnTypeIn.fir.kt
@@ -0,0 +1,61 @@
+// FILE: InOut.kt
+interface In<in T>
+
+// FILE: J1.java
+public interface J1 {
+    In<String> foo();
+}
+
+// FILE: J2.java
+import org.jetbrains.annotations.*;
+
+public interface J2 {
+    @NotNull In<String> foo();
+}
+
+// FILE: J3.java
+import org.jetbrains.annotations.*;
+
+public interface J3 {
+    @Nullable In<String> foo();
+}
+
+// FILE: K.kt
+interface K1 {
+    fun foo(): In<String>
+}
+
+interface K2 {
+    fun foo(): In<String?>
+}
+
+// FIXME TestJ1K1 should have foo(): In<String!>, since In<String!> <: In<String>.
+interface TestJ1K1 : J1, K1
+interface TestK1J1 : K1, J1
+
+interface TestJ1K2 : J1, K2
+interface TestK2J1 : K2, J1
+
+interface TestJ2K1 : J2, K1
+interface TestK1J2 : K1, J2
+
+interface TestJ2K2 : J2, K2
+interface TestK2J2 : K2, J2
+
+interface TestJ3K1 : J3, K1
+interface TestK1J3 : K1, J3
+
+interface TestJ3K2 : J3, K2
+interface TestK2J3 : K2, J3
+
+interface TestJ1K1K2 : J1, K1, K2
+interface TestK1J1K2 : K1, J1, K2
+interface TestK1K2J1 : K1, K2, J1
+
+interface TestJ2K1K2 : J2, K1, K2
+interface TestK1J2K2 : K1, J2, K2
+interface TestK1K2J2 : K1, K2, J2
+
+interface TestJ3K1K2 : J3, K1, K2
+interface TestK1J3K2 : K1, J3, K2
+interface TestK1K2J3 : K1, K2, J3
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnTypeList.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnTypeList.fir.kt
new file mode 100644
index 00000000000..5c7598aafaf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/flexibleReturnTypeList.fir.kt
@@ -0,0 +1,43 @@
+// FILE: J.java
+public interface J {
+    java.util.List<String> foo();
+}
+
+// FILE: K.kt
+interface ILNS {
+    fun foo(): List<String?>
+}
+
+interface IMLS {
+    fun foo(): MutableList<String>
+}
+
+interface IMLNS {
+    fun foo(): MutableList<String?>
+}
+
+interface ILS {
+    fun foo(): List<String>
+}
+
+interface Test1 : ILNS, J
+interface Test2 : J, ILNS
+
+interface Test3 : IMLS, J
+interface Test4 : J, IMLS
+
+interface Test5 : ILNS, IMLS, J
+interface Test6 : ILNS, J, IMLS
+interface Test7 : J, ILNS, IMLS
+
+// Return types of ILS::foo and IMLNS::foo are incompatible themselves.
+// However, return type of J::foo is (Mutable)List<String!>!,
+// which is subtype of both List<String> and MutalbeList<String?>.
+// Thus, inheriting from J, IMLNS, and ILS is Ok,
+// but inheriting from IMLNS and ILS is not.
+
+interface Test8 : J, IMLNS, ILS
+interface Test9 : IMLNS, J, ILS
+interface Test10 : IMLNS, ILS, J
+
+interface Test11 : IMLNS, ILS
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/genericWithUpperBound.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/genericWithUpperBound.fir.kt
new file mode 100644
index 00000000000..453cbb87571
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/genericWithUpperBound.fir.kt
@@ -0,0 +1,56 @@
+// FILE: JFooWithUpperBound.java
+public interface JFooWithUpperBound<T extends IBase> {
+    T foo();
+}
+
+// FILE: JFooWithUpperBoundDerived.java
+public interface JFooWithUpperBoundDerived<T extends IBase> extends JFooWithUpperBound<T> {
+}
+
+// FILE: JCFooWithUpperBound.java
+public class JCFooWithUpperBound<T extends IBase> {
+    public T foo() {
+        return null;
+    }
+}
+
+// FILE: JCFooWithUpperBoundDerived.java
+public class JCFooWithUpperBoundDerived<T extends IBase> extends JCFooWithUpperBound<T> {
+}
+
+// FILE: K.kt
+interface IBase
+
+interface IDerived : IBase
+
+interface IFooWithUpperBound<T : IBase> {
+    fun foo(): T
+}
+
+interface IFooT<T> {
+    fun foo(): T
+}
+
+interface IFoo {
+    fun foo(): IBase
+}
+
+interface IFooDerived : IFoo {
+    override fun foo(): IDerived
+}
+
+interface IFooWithUpperBoundDerived<T : IBase> : IFooWithUpperBound<T>
+
+interface Test1<T : IBase> : IFooWithUpperBound<T>, IFoo
+
+interface Test2<T : IBase> : IFooT<T>, IFoo
+
+interface Test3<T : IDerived> : IFooWithUpperBoundDerived<T>, IFooDerived
+
+interface Test4<T : IBase> : JFooWithUpperBound<T>, IFoo
+
+interface Test5<T : IDerived> : JFooWithUpperBoundDerived<T>, IFooDerived
+
+class Test6<T : IBase> : JCFooWithUpperBound<T>(), IFoo
+
+class Test7<T : IDerived> : JCFooWithUpperBoundDerived<T>(), IFooDerived
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355.fir.kt
new file mode 100644
index 00000000000..7d3db4e4f22
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355.fir.kt
@@ -0,0 +1,13 @@
+interface IFooAny {
+    val foo: Any
+}
+
+interface IFooStr : IFooAny {
+    override val foo: String
+}
+
+abstract class BaseAny(override val foo: Any): IFooAny
+
+abstract class BaseStr : BaseAny(42), IFooStr
+
+class C : BaseStr()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355viaJava.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355viaJava.fir.kt
new file mode 100644
index 00000000000..0ad54762042
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt13355viaJava.fir.kt
@@ -0,0 +1,47 @@
+// FILE: K.kt
+abstract class ATest1 : TestNN.JNullVsNotNull()
+
+abstract class ATest2 : TestNN.JUnknownImpl(), TestNN.JNotNull
+
+abstract class ATest3 : TestNN.JUnknownVsNotNull()
+
+class CTest1 : TestNN.JNullVsNotNull()
+
+class CTest2 : TestNN.JUnknownImpl(), TestNN.JNotNull
+
+class CTest3 : TestNN.JUnknownVsNotNull()
+
+// FILE: TestNN.java
+import org.jetbrains.annotations.*;
+
+public class TestNN {
+    public interface JNull {
+        @Nullable Object foo();
+    }
+
+    public interface JNotNull {
+        @NotNull Object foo();
+    }
+
+    public static class JNullVsNotNull implements JNull, JNotNull {
+        public Object foo() {
+            return this;
+        }
+    }
+
+    public static class JNullBase {
+        @Nullable public Object foo() {
+            return null;
+        }
+    }
+
+    public static class JUnknownImpl extends JNullBase {
+        public Object foo() {
+            return this;
+        }
+    }
+
+    public static class JUnknownVsNotNull extends JUnknownImpl implements JNotNull {
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.fir.kt
new file mode 100644
index 00000000000..054e69b9189
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/kt9550.fir.kt
@@ -0,0 +1,13 @@
+interface A {
+    fun <T> foo()
+    fun <T> bar()
+}
+
+interface B {
+    fun foo()
+    fun bar()
+}
+
+interface C1 : A, B {
+    override fun bar()
+}
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/returnTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/returnTypeMismatch.fir.kt
new file mode 100644
index 00000000000..93f1a1414fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/returnTypeMismatch.fir.kt
@@ -0,0 +1,29 @@
+open class A {
+    open fun foo(): Boolean = true
+}
+
+interface IA {
+    fun foo(): String
+}
+
+interface IAA {
+    fun foo(): Int
+}
+
+interface IGA<T> {
+    fun foo(): T
+}
+
+class B1: A(), IA
+
+class B2: A(), IA, IAA
+
+abstract class B3: IA, IAA
+
+class BS1: A(), IGA<Boolean>
+
+class BS2: A(), IGA<Any>
+
+class BS3: A(), IGA<String>
+
+class BG1<T>: A(), IGA<T>
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/unrelatedInherited.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/unrelatedInherited.fir.kt
new file mode 100644
index 00000000000..c8b6efc9e1d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/unrelatedInherited.fir.kt
@@ -0,0 +1,33 @@
+interface IA {
+    fun method(): String
+    val propVal: String
+    var propVar: String
+}
+
+interface IB1 : IA
+interface IB2 : IA
+
+interface IGA<T> {
+    fun method(): T
+    val propVal: T
+    var propVar: T
+}
+
+interface IGB1Str : IGA<String>
+interface IGB2Str : IGA<String>
+interface IGB3Int : IGA<Int>
+
+interface IGB4T<T> : IGA<T>
+interface IGB5T<T> : IGA<T>
+
+interface IC : IB1, IB2
+
+interface IGC1 : IGB1Str, IGB2Str
+
+interface IGC2 : IGB1Str, IGB3Int
+
+interface IGC3<T> : IGB4T<T>, IGB5T<T>
+
+interface IGC4<T> : IGB4T<T>, IGB5T<String>
+
+interface IGC5 : IGB4T<String>, IGB5T<String>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/valTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/valTypeMismatch.fir.kt
new file mode 100644
index 00000000000..a46c47515ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/valTypeMismatch.fir.kt
@@ -0,0 +1,29 @@
+open class A {
+    open val foo: Boolean = true
+}
+
+interface IA {
+    val foo: String
+}
+
+interface IAA {
+    val foo: Int
+}
+
+interface IGA<T> {
+    val foo: T
+}
+
+class B1: A(), IA
+
+class B2: A(), IA, IAA
+
+abstract class B3: IA, IAA
+
+class BS1: A(), IGA<Boolean>
+
+class BS2: A(), IGA<Any>
+
+class BS3: A(), IGA<String>
+
+class BG1<T>: A(), IGA<T>
diff --git a/compiler/testData/diagnostics/tests/override/clashesOnInheritance/varTypeMismatch.fir.kt b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/varTypeMismatch.fir.kt
new file mode 100644
index 00000000000..81f5a80065e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/clashesOnInheritance/varTypeMismatch.fir.kt
@@ -0,0 +1,29 @@
+open class A {
+    open var foo: Boolean = true
+}
+
+interface IA {
+    var foo: String
+}
+
+interface IAA {
+    var foo: Int
+}
+
+interface IGA<T> {
+    var foo: T
+}
+
+class B1: A(), IA
+
+class B2: A(), IA, IAA
+
+abstract class B3: IA, IAA
+
+class BS1: A(), IGA<Boolean>
+
+class BS2: A(), IGA<Any>
+
+class BS3: A(), IGA<String>
+
+class BG1<T>: A(), IGA<T>
diff --git a/compiler/testData/diagnostics/tests/override/fakeEquals.fir.kt b/compiler/testData/diagnostics/tests/override/fakeEquals.fir.kt
new file mode 100644
index 00000000000..81e96a21e8b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/fakeEquals.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_REFERENCE
+
+class Foo
+
+fun test(a: Foo, b: Foo) {
+    // Note that signature matches the 'equals'
+    fun equals(x: Any?): Boolean = false
+    equals(b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/kt12358.fir.kt b/compiler/testData/diagnostics/tests/override/kt12358.fir.kt
new file mode 100644
index 00000000000..74b73cf0ba5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt12358.fir.kt
@@ -0,0 +1,9 @@
+abstract class A {
+    abstract override fun toString(): String
+}
+
+interface B
+
+abstract class C : A(), B
+
+class Test : C()
diff --git a/compiler/testData/diagnostics/tests/override/kt12467.fir.kt b/compiler/testData/diagnostics/tests/override/kt12467.fir.kt
new file mode 100644
index 00000000000..a6028721b18
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt12467.fir.kt
@@ -0,0 +1,14 @@
+interface A {
+    fun test() {
+    }
+}
+
+interface B : A {
+    override fun test()
+}
+
+interface C : A
+
+interface D : C, B
+
+class K : D
diff --git a/compiler/testData/diagnostics/tests/override/kt12482.fir.kt b/compiler/testData/diagnostics/tests/override/kt12482.fir.kt
new file mode 100644
index 00000000000..db5999b06e5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt12482.fir.kt
@@ -0,0 +1,11 @@
+interface A {
+    fun test(): String = "A"
+}
+
+interface B : A {
+    override fun test(): Unit = "B"
+}
+
+open class C : A
+
+class D : C(), B
diff --git a/compiler/testData/diagnostics/tests/override/kt1862.fir.kt b/compiler/testData/diagnostics/tests/override/kt1862.fir.kt
new file mode 100644
index 00000000000..0cc1c2ab5f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt1862.fir.kt
@@ -0,0 +1,11 @@
+open class Aaa() {
+    open fun foo() = 1
+}
+
+open class Bbb() : Aaa() {
+    override fun foo() = 2
+}
+
+interface Ccc : Aaa
+
+class Ddd() : Bbb(), Ccc
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/kt2052.fir.kt b/compiler/testData/diagnostics/tests/override/kt2052.fir.kt
new file mode 100644
index 00000000000..6b263071aa5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt2052.fir.kt
@@ -0,0 +1,10 @@
+interface Runnable {
+    fun run()
+}
+
+class C {
+    fun f() {
+        class MyRunnable(): Runnable {
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/kt2491.fir.kt b/compiler/testData/diagnostics/tests/override/kt2491.fir.kt
new file mode 100644
index 00000000000..988ed79e63e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt2491.fir.kt
@@ -0,0 +1,11 @@
+interface T {
+    public fun foo()
+}
+
+open class C {
+    protected fun foo() {}
+}
+
+class D : C(), T
+
+val obj: C = object : C(), T {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/kt4763.fir.kt b/compiler/testData/diagnostics/tests/override/kt4763.fir.kt
new file mode 100644
index 00000000000..0f18e051678
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt4763.fir.kt
@@ -0,0 +1,11 @@
+interface A {
+    fun f(): String
+}
+
+open class B {
+    open fun f(): CharSequence = "charSequence"
+}
+
+class C : B(), A
+
+val d: A = object : B(), A {}
diff --git a/compiler/testData/diagnostics/tests/override/kt4763property.fir.kt b/compiler/testData/diagnostics/tests/override/kt4763property.fir.kt
new file mode 100644
index 00000000000..e14e07a22f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt4763property.fir.kt
@@ -0,0 +1,11 @@
+interface P {
+    var f: Number
+}
+
+open class Q {
+    val x: Int = 42
+}
+
+class R : P, Q()
+
+val s: Q = object : Q(), P {}
diff --git a/compiler/testData/diagnostics/tests/override/kt4785.fir.kt b/compiler/testData/diagnostics/tests/override/kt4785.fir.kt
new file mode 100644
index 00000000000..7db8c26e68b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt4785.fir.kt
@@ -0,0 +1,11 @@
+interface T {
+    fun foo()
+}
+
+open class C {
+    protected fun foo() {}
+}
+
+class E : C(), T
+
+val z: T = object : C(), T {}
diff --git a/compiler/testData/diagnostics/tests/override/kt6014.fir.kt b/compiler/testData/diagnostics/tests/override/kt6014.fir.kt
new file mode 100644
index 00000000000..a8ecad03d8d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt6014.fir.kt
@@ -0,0 +1,17 @@
+interface IBase {
+    override fun toString(): String
+}
+
+interface IDerived : IBase
+
+object BaseImpl : IBase {
+    override fun toString(): String = "A"
+}
+
+object DerivedImpl : IDerived {
+    override fun toString(): String = "A"
+}
+
+class Test1 : IBase by BaseImpl
+
+class Test2 : IDerived by DerivedImpl
diff --git a/compiler/testData/diagnostics/tests/override/kt880.fir.kt b/compiler/testData/diagnostics/tests/override/kt880.fir.kt
new file mode 100644
index 00000000000..814e808b9fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt880.fir.kt
@@ -0,0 +1,16 @@
+// KT-880 Overload resolution ambiguity
+
+public interface I {
+    open fun test() : Unit
+}
+
+abstract public class A() {
+    open public fun test() : Unit {
+    }
+}
+
+public open class T() : A(), I {
+    open fun main() : Unit {
+        test() // Test no "Overload resolution ambiguity" is here
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/kt8990.fir.kt b/compiler/testData/diagnostics/tests/override/kt8990.fir.kt
new file mode 100644
index 00000000000..ca218fc52c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/kt8990.fir.kt
@@ -0,0 +1,11 @@
+open class A {
+    private fun foo() {}
+
+    inner class B : A() {
+        private fun foo() {}
+    }
+}
+
+class C : A() {
+    private fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/overrideMemberFromFinalClass.fir.kt b/compiler/testData/diagnostics/tests/override/overrideMemberFromFinalClass.fir.kt
new file mode 100644
index 00000000000..c0430ca06a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/overrideMemberFromFinalClass.fir.kt
@@ -0,0 +1,28 @@
+class Foo {
+    open fun openFoo() {}
+    fun finalFoo() {}
+}
+
+class Bar : Foo() {
+    override fun openFoo() {}
+    override fun finalFoo() {}
+}
+
+
+open class A1 {
+    open fun foo() {}
+}
+
+class B1 : A1()
+class C1 : B1() {
+    override fun foo() {}
+}
+
+abstract class A2 {
+    abstract fun foo()
+}
+
+class B2 : A2()
+class C2 : B2() {
+    override fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/changeOnOverrideDiagnostic.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/changeOnOverrideDiagnostic.fir.kt
new file mode 100644
index 00000000000..8a0a91be12d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/changeOnOverrideDiagnostic.fir.kt
@@ -0,0 +1,13 @@
+interface A {
+    fun b(a : Int)
+}
+
+interface B : A {}
+
+class C1 : A {
+    override fun b(b : Int) {}
+}
+
+class C2 : B {
+    override fun b(b : Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/differentNamesInSupertypesDiagnostic.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/differentNamesInSupertypesDiagnostic.fir.kt
new file mode 100644
index 00000000000..cfb3941a6ce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/differentNamesInSupertypesDiagnostic.fir.kt
@@ -0,0 +1,15 @@
+interface C {
+    fun foo(a : Int)
+}
+
+interface D {
+    fun foo(b : Int)
+}
+
+interface E : C, D
+
+interface F : C, D {
+    override fun foo(a : Int) {
+        throw UnsupportedOperationException()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/invokeInFunctionClass.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/invokeInFunctionClass.fir.kt
new file mode 100644
index 00000000000..5fa63c79496
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/invokeInFunctionClass.fir.kt
@@ -0,0 +1,27 @@
+class Function1Impl : (String) -> Unit {
+    override fun invoke(myParamName: String) {}
+}
+
+fun test1(f: Function1Impl) {
+    f("")
+    <!INAPPLICABLE_CANDIDATE!>f<!>(p0 = "")
+    f(myParamName = "")
+    f.invoke("")
+    f.<!INAPPLICABLE_CANDIDATE!>invoke<!>(p0 = "")
+    f.invoke(myParamName = "")
+}
+
+fun test2(f: (String) -> Unit) {
+    f("")
+    <!INAPPLICABLE_CANDIDATE!>f<!>(p0 = "")
+    <!INAPPLICABLE_CANDIDATE!>f<!>(myParamName = "")
+    f.invoke("")
+    f.<!INAPPLICABLE_CANDIDATE!>invoke<!>(p0 = "")
+    f.<!INAPPLICABLE_CANDIDATE!>invoke<!>(myParamName = "")
+}
+
+fun test3(f: String.(String) -> Unit) {
+    "".<!UNRESOLVED_REFERENCE!>f<!>("")
+    "".<!UNRESOLVED_REFERENCE!>f<!>(p0 = "")
+    "".<!UNRESOLVED_REFERENCE!>f<!>(zzz = "")
+}
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/jjkHierarchy.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/jjkHierarchy.fir.kt
new file mode 100644
index 00000000000..dacf0a11ff9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/jjkHierarchy.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Super.java
+
+interface Super {
+    void foo(long superName);
+}
+
+// FILE: Sub.java
+
+interface Sub extends Super {
+}
+
+// FILE: SubSub.kt
+
+class SubSub : Sub {
+    override fun foo(subName: Long) {}
+}
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/kjkHierarchy.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/kjkHierarchy.fir.kt
new file mode 100644
index 00000000000..75f7d2c4112
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/kjkHierarchy.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Super.kt
+
+interface Super {
+    fun foo(superName: Int)
+}
+
+// FILE: Sub.java
+
+interface Sub extends Super {
+}
+
+// FILE: SubSub.kt
+
+class SubSub : Sub {
+    override fun foo(subName: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/kjkWithSeveralSupers.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/kjkWithSeveralSupers.fir.kt
new file mode 100644
index 00000000000..32527db7597
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/kjkWithSeveralSupers.fir.kt
@@ -0,0 +1,51 @@
+// FILE: KSuper.kt
+
+interface KSuper {
+    fun foo(ksuperName: Int)
+}
+
+// FILE: JSuper1.java
+
+interface JSuper1 {
+    void foo(int jsuper1Name);
+}
+
+// FILE: JSuper2.java
+
+interface JSuper2 {
+    void foo(int jsuper2Name);
+}
+
+
+// FILE: Sub1.java
+interface Sub1 extends KSuper, JSuper1, JSuper2 {
+    @Override
+    void foo(int sub1Name);
+}
+
+// FILE: Sub2.java
+interface Sub2 extends JSuper1, KSuper, JSuper2 {
+    @Override
+    void foo(int sub2Name);
+}
+
+// FILE: Sub3.java
+interface Sub3 extends JSuper1, JSuper2, KSuper {
+    @Override
+    void foo(int sub3Name);
+}
+
+
+// FILE: SubSub.kt
+
+class SubSub1 : Sub1 {
+    override fun foo(ksuperName: Int) {}
+}
+
+class SubSub2 : Sub2 {
+    override fun foo(ksuperName: Int) {}
+}
+
+class SubSub3 : Sub3 {
+    override fun foo(ksuperName: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/kotlinInheritsBothJavaAndKotlin.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/kotlinInheritsBothJavaAndKotlin.fir.kt
new file mode 100644
index 00000000000..7845a3c17bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/kotlinInheritsBothJavaAndKotlin.fir.kt
@@ -0,0 +1,13 @@
+// FILE: JavaInterface.java
+
+interface JavaInterface {
+    void foo(int javaName);
+}
+
+// FILE: kotlin.kt
+
+interface KotlinTrait {
+    public fun foo(someOtherName: Int) {}
+}
+
+class BothTraitsSubclass : JavaInterface, KotlinTrait
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/override/parameterNames/kotlinInheritsJava.fir.kt b/compiler/testData/diagnostics/tests/override/parameterNames/kotlinInheritsJava.fir.kt
new file mode 100644
index 00000000000..1e7d997c393
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/parameterNames/kotlinInheritsJava.fir.kt
@@ -0,0 +1,18 @@
+// FILE: JavaInterface.java
+
+public interface JavaInterface {
+    void foo(int javaName);
+}
+
+// FILE: kotlin.kt
+
+class SimpleSubclass : JavaInterface {
+    override fun foo(kotlinName: Int) {}
+}
+
+
+interface SubtraitWithFakeOverride : JavaInterface
+
+class Subclass : SubtraitWithFakeOverride {
+    override fun foo(otherKotlinName: Int) {}
+}
diff --git a/compiler/testData/diagnostics/tests/override/typeParameters/classAndTwoInterfaceBounds.fir.kt b/compiler/testData/diagnostics/tests/override/typeParameters/classAndTwoInterfaceBounds.fir.kt
new file mode 100644
index 00000000000..61f5cf91a8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/typeParameters/classAndTwoInterfaceBounds.fir.kt
@@ -0,0 +1,31 @@
+interface I1
+interface I2
+open class C
+
+interface A {
+    fun <T> foo(t: T) where T : I1, T : C, T : I2
+}
+
+interface B1 : A {
+    override fun <T> foo(t: T) where T : C, T : I1, T : I2
+}
+
+interface B2 : A {
+    override fun <T> foo(t: T) where T : I1, T : C, T : I2
+}
+
+interface B3 : A {
+    override fun <T> foo(t: T) where T : I1, T : I2, T : C
+}
+
+interface B4 : A {
+    override fun <T> foo(t: T) where T : C, T : I2, T : I1
+}
+
+interface B5 : A {
+    override fun <T> foo(t: T) where T : I2, T : C, T : I1
+}
+
+interface B6 : A {
+    override fun <T> foo(t: T) where T : I2, T : I1, T : C
+}
diff --git a/compiler/testData/diagnostics/tests/override/typeParameters/differentSetsOfBounds.fir.kt b/compiler/testData/diagnostics/tests/override/typeParameters/differentSetsOfBounds.fir.kt
new file mode 100644
index 00000000000..efe77a95f12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/typeParameters/differentSetsOfBounds.fir.kt
@@ -0,0 +1,7 @@
+interface A {
+    fun <T> foo() where T : Any, T : Cloneable?
+}
+
+interface B : A {
+    override fun <T> foo() where T : Any?, T : Cloneable
+}
diff --git a/compiler/testData/diagnostics/tests/override/typeParameters/kt9850.fir.kt b/compiler/testData/diagnostics/tests/override/typeParameters/kt9850.fir.kt
new file mode 100644
index 00000000000..413c36eebd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/typeParameters/kt9850.fir.kt
@@ -0,0 +1,8 @@
+abstract class Base {
+    abstract fun <T> foo(list: List<T>) where T : Number, T : Comparable<T>
+}
+
+class Derived : Base() {
+    override fun <T> foo(list: List<T>) where T : Number, T : Comparable<T> {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/override/typeParameters/simpleVisitorTwoAccepts.fir.kt b/compiler/testData/diagnostics/tests/override/typeParameters/simpleVisitorTwoAccepts.fir.kt
new file mode 100644
index 00000000000..37d3705f995
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/override/typeParameters/simpleVisitorTwoAccepts.fir.kt
@@ -0,0 +1,10 @@
+interface A<R>
+
+interface B {
+    fun accept(visitor: String)
+    fun <R> accept(visitor: A<R>): R
+}
+
+interface C : B {
+    override fun <R> accept(visitor: A<R>): R
+}
diff --git a/compiler/testData/diagnostics/tests/parenthesizedTypes/annotationsOnNullableParenthesizedTypes.fir.kt b/compiler/testData/diagnostics/tests/parenthesizedTypes/annotationsOnNullableParenthesizedTypes.fir.kt
new file mode 100644
index 00000000000..a33e3c04054
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/parenthesizedTypes/annotationsOnNullableParenthesizedTypes.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface AnnotationsOnNullableParenthesizedTypes {
+    fun B<(@A C)?>.receiverArgument() {}
+
+    fun parameter(a: (@A C)?) {}
+
+    fun parameterArgument(a: B<(@A C)?>) {}
+
+    fun returnValue(): (@A C)?
+
+    fun <T> returnTypeParameterValue(): (@A T)?
+
+    fun returnArgument(): B<(@A C)?>
+
+    val lambdaType: (@A() (() -> C))?
+
+    val lambdaParameter: ((@A C)?) -> C
+
+    val lambdaReturnValue: () -> (@A C)?
+
+    val lambdaReceiver: (@A C)?.() -> C
+}
+
+@Target(AnnotationTarget.TYPE, AnnotationTarget.TYPE_PARAMETER)
+annotation class A
+
+interface B<T>
+interface C
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/parenthesizedTypes/annotationsOnParenthesizedTypes.fir.kt b/compiler/testData/diagnostics/tests/parenthesizedTypes/annotationsOnParenthesizedTypes.fir.kt
new file mode 100644
index 00000000000..ab5e5e046e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/parenthesizedTypes/annotationsOnParenthesizedTypes.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface AnnotationsOnParenthesizedTypes {
+    fun B<(@A C)>.receiverArgument() {}
+
+    fun parameter(a: (@A C)) {}
+
+    fun parameterArgument(a: B<(@A C)>) {}
+
+    fun returnValue(): (@A C)
+
+    fun <T> returnTypeParameterValue(): (@A T)
+
+    fun returnArgument(): B<(@A C)>
+
+    val lambdaType: (@A() (() -> C))
+
+    val lambdaParameter: ((@A C)) -> C
+
+    val lambdaReturnValue: () -> (@A C)
+
+    val lambdaReceiver: (@A C).() -> C
+
+    val lambdaParameterNP: (@A C) -> C
+}
+
+@Target(AnnotationTarget.TYPE, AnnotationTarget.TYPE_PARAMETER)
+annotation class A
+
+interface B<T>
+interface C
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/parenthesizedTypes/splitModifierList.fir.kt b/compiler/testData/diagnostics/tests/parenthesizedTypes/splitModifierList.fir.kt
new file mode 100644
index 00000000000..0e41b321904
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/parenthesizedTypes/splitModifierList.fir.kt
@@ -0,0 +1,16 @@
+@Target(AnnotationTarget.TYPE, AnnotationTarget.TYPE_PARAMETER)
+annotation class A
+
+@Target(AnnotationTarget.TYPE, AnnotationTarget.TYPE_PARAMETER)
+annotation class B
+
+typealias Test0 = @A @B Int
+typealias Test1 = @A() (@A Int)
+typealias Test2 = @A() (@B Int)
+typealias Test3 = @A() (@A Int) -> Int
+typealias Test4 = @A() (@B Int)?
+typealias Test5 = @A() ( (@B Int)? )
+typealias Test6 = (@A @B Int)
+typealias Test7 = (@A @B Int)?
+typealias Test8 = (@A() (@B Int)? )
+typealias Test9 = (@A() (@B Int)  )?
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/collectionOrNull.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/collectionOrNull.fir.kt
new file mode 100644
index 00000000000..73340ce072f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/collectionOrNull.fir.kt
@@ -0,0 +1,19 @@
+// FILE: p/Utils.java
+
+package p;
+
+public class Utils {
+    public static java.util.Collection<String> c() { return null; }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun <T : Any> T.foo() {}
+
+fun <D> test(b: Boolean) {
+    val c = if (b) Utils.c() else null
+
+    c?.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/inferenceWithBound.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/inferenceWithBound.fir.kt
new file mode 100644
index 00000000000..4a4d125e162
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/inferenceWithBound.fir.kt
@@ -0,0 +1,41 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: p/Super.java
+
+package p;
+
+public interface Super {
+
+}
+
+// FILE: p/Sub.java
+
+package p;
+
+public interface Sub extends Super {}
+
+// FILE: p/Other.java
+
+package p;
+
+import java.util.*;
+
+public class Other {
+
+    public static Sub sub;
+
+    public static Collection<Sub> subs;
+    public static Collection<Super> supers;
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test() {
+    val col = if (1 < 2) Other.subs else Other.supers
+    col.foo()
+}
+
+fun <T: Super> Collection<T>.foo(): T = null!!
+fun <T> listOf(t: T): List<T> = null!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/mixedElvis.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/mixedElvis.fir.kt
new file mode 100644
index 00000000000..eab1285e638
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/mixedElvis.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !CHECK_TYPE
+
+import java.util.ArrayList
+
+fun foo(handlers: Array<MutableList<String>?>) {
+    val v = handlers[0] ?: ArrayList<String>()
+    handlers[0] = v
+    val js: MutableList<String> = v
+    // TODO: fix with dominance
+//    v checkType { it : _<MutableList<String>>}
+//    v checkType { it : _<MutableList<String?>>}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/mixedIf.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/mixedIf.fir.kt
new file mode 100644
index 00000000000..5c1639e3079
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/mixedIf.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !CHECK_TYPE
+// FILE: p/J.java
+
+package p;
+
+public class J<G> {
+    public static J<String> j() { return null; }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun foo(j: J<String>) {
+    val v = if (true) j else J.j()
+    val js: J<String> = v
+    // TODO: fix with dominance
+//    v checkType { it : _<J<String>>}
+//    v checkType { it : _<J<String?>>}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/recursiveGeneric.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/recursiveGeneric.fir.kt
new file mode 100644
index 00000000000..fd370e7547e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/recursiveGeneric.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE
+
+// FILE: p/Rec.java
+
+package p;
+
+public interface Rec<T> {
+
+}
+
+// FILE: p/A.java
+
+package p;
+
+public interface A extends Rec<A> {
+
+}
+
+// FILE: p/B.java
+
+package p;
+
+public interface B extends Rec<B> {
+
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(a: A, b: B, c: Boolean) {
+    var ab = if (c) a else b
+    ab = a
+    ab = b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/stringOrNull.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/stringOrNull.fir.kt
new file mode 100644
index 00000000000..79e2df864bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/stringOrNull.fir.kt
@@ -0,0 +1,19 @@
+// FILE: p/Utils.java
+
+package p;
+
+public class Utils {
+    public static String str() { return null; }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun <T : Any> T.foo() {}
+
+fun <D> test(b: Boolean) {
+    val str = if (b) Utils.str() else null
+
+    str?.foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/typeOfElvis.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/typeOfElvis.fir.kt
new file mode 100644
index 00000000000..907f324a43b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/typeOfElvis.fir.kt
@@ -0,0 +1,20 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public static J j() { return null; }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun foo(): J? = null
+
+fun main() {
+    val v = foo() ?: J.j()
+    if (v != null) {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/withNothing.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/withNothing.fir.kt
new file mode 100644
index 00000000000..83c5ac36b0a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/commonSupertype/withNothing.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// JAVAC_SKIP
+// NI_EXPECTED_FILE
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public static J j() { return null; }
+}
+
+// FILE: k.kt
+
+import p.*
+
+interface Out<out T1>
+
+fun <T> f(a: Out<T>, b: Out<T>, c: Out<T>): T = null!!
+fun <T> out(t: T): Out<MutableList<T>> = null!!
+
+fun test(a: Out<Nothing>, b: Out<MutableList<J>>) {
+    val v = f(a, b, out(J.j()))
+    v checkType { <!UNRESOLVED_REFERENCE!>_<!><MutableList<J>>() }
+    v checkType { <!UNRESOLVED_REFERENCE!>_<!><MutableList<J?>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/delegateByComplexInheritance.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/delegateByComplexInheritance.fir.kt
new file mode 100644
index 00000000000..ffc1f27d5dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/delegateByComplexInheritance.fir.kt
@@ -0,0 +1,15 @@
+// FILE: A.java
+
+import java.util.*;
+
+public interface A {
+    <R> void foo();
+}
+
+// FILE: B.java
+
+public interface B extends A {}
+
+// FILE: k.kt
+
+class C(x: A) : A by x, B {}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/dereference.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/dereference.fir.kt
new file mode 100644
index 00000000000..78a8bfaae72
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/dereference.fir.kt
@@ -0,0 +1,30 @@
+// !CHECK_TYPE
+
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public J j() {return null;}
+
+    public <T> T foo() {return null;}
+    public <T extends J> T foo1() {return null;}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(j: J) {
+    checkSubtype<J>(j.j())
+    j.j().j()
+    j.j()!!.j()
+
+    val ann = j.foo<String>()
+    ann!!.length
+    ann.length
+
+    val a = j.foo<J>()
+    a!!.j()
+    a.j()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/elvis.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/elvis.fir.kt
new file mode 100644
index 00000000000..ce6b32105a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/elvis.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public String s() { return null; }
+}
+
+// FILE: k.kt
+import p.*
+
+fun test(j: J) {
+    j.s()?.length ?: ""
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/explicitFlexibleNoPackage.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/explicitFlexibleNoPackage.fir.kt
new file mode 100644
index 00000000000..cf6f0e4f55c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/explicitFlexibleNoPackage.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !EXPLICIT_FLEXIBLE_TYPES
+// !CHECK_TYPE
+
+fun foo(f: ft<Int, Int?>) {
+    f.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+    f.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int?>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/explicitFlexibleWithPackage.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/explicitFlexibleWithPackage.fir.kt
new file mode 100644
index 00000000000..571418a21e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/explicitFlexibleWithPackage.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !EXPLICIT_FLEXIBLE_TYPES
+// !CHECK_TYPE
+package ppp
+
+fun foo(f: ft<Int, Int?>) {
+    f.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+    f.checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Int?>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/listSuperType.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/listSuperType.fir.kt
new file mode 100644
index 00000000000..d14ca7e5698
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/listSuperType.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(List<Object> x) {}
+}
+// FILE: main.kt
+
+abstract class B : MutableList<String>
+
+fun main(a: A, b: B) {
+    a.foo(b)
+    a.foo(b as List<Any>)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/rawTypes.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/rawTypes.fir.kt
new file mode 100644
index 00000000000..6be7f3dcf05
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/rawTypes.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(List x) {}
+}
+// FILE: main.kt
+
+fun main(a: A, ml: MutableList<String>, l: List<String>) {
+    a.foo(ml)
+    a.foo(l)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/simple.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/simple.fir.kt
new file mode 100644
index 00000000000..7ee4ad14d0d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/simple.fir.kt
@@ -0,0 +1,67 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(List<Object> x) {}
+    void foo(Iterable<Object> x) {}
+    void foo(Iterator<Object> x) {}
+    void foo(Set<Object> x) {}
+    void foo(Map<Object, Object> x) {}
+    void foo(Map.Entry<Object, Object> x) {}
+
+    void foo(List<List<Object>> x) {}
+}
+
+// FILE: main.kt
+
+fun main(
+        a: A,
+        ml: MutableList<String>, l: List<String>,
+        ms: MutableSet<String>, s: Set<String>,
+        mm: MutableMap<Any, String>, m: Map<Any, String>,
+        mme: MutableMap.MutableEntry<Any, String>, me: Map.Entry<Any, String>,
+        mll: MutableList<MutableList<String>>, ll: List<List<String>>
+) {
+    // Lists
+    a.foo(ml)
+    a.foo(l)
+    a.foo(ml as MutableList<Any>)
+    a.foo(l as List<Any>)
+
+    // Iterables
+    val mit: MutableIterable<String> = ml
+    val it: Iterable<String> = ml
+    a.foo(mit)
+    a.foo(it)
+
+    // Iterators
+    a.<!AMBIGUITY!>foo<!>(ml.<!AMBIGUITY!>iterator<!>())
+    a.foo(l.iterator())
+
+    // Sets
+    a.foo(ms)
+    a.foo(s)
+    a.foo(ms as MutableSet<Any>)
+    a.foo(s as Set<Any>)
+
+    // Maps
+    a.foo(mm)
+    a.foo(m)
+    a.foo(mm as MutableMap<Any, Any>)
+    a.foo(m as Map<Any, Any>)
+
+    // Map entries
+    a.foo(mme)
+    a.foo(me)
+    a.foo(mme as MutableMap.MutableEntry<Any, Any>)
+    a.foo(me as Map.Entry<Any, Any>)
+
+    // Lists of lists
+    a.foo(mll)
+    a.foo(ll)
+    a.foo(mll as MutableList<MutableList<Any>>)
+    a.foo(ll as List<List<Any>>)
+
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/smartCast.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/smartCast.fir.kt
new file mode 100644
index 00000000000..e5b210a4c71
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/smartCast.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(List<Object> x) {}
+}
+// FILE: main.kt
+
+fun main(a: A, ml: Any) {
+    if (ml is MutableList<String>) {
+        a.foo(ml)
+        a.foo(ml as List<Any>)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/strangeVariance.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/strangeVariance.fir.kt
new file mode 100644
index 00000000000..f4610b66e4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/strangeVariance.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(List<? super String> x) {}
+    void bar(List<? super Object> x) {}
+}
+// FILE: main.kt
+
+fun main(a: A, ml: MutableList<String>, l: List<String>) {
+    a.foo(ml)
+    a.foo(l)
+
+    a.bar(ml)
+    a.bar(l)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/userDefinedOut.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/userDefinedOut.fir.kt
new file mode 100644
index 00000000000..f06e8d918d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/userDefinedOut.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(Out<Object> x) {}
+    void bar(Out<? extends Object> x) {}
+}
+// FILE: main.kt
+
+public class Out<out T>()
+
+fun main(a: A, o: Out<String>) {
+    a.foo(o)
+    a.bar(o)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/valueFromJava.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/valueFromJava.fir.kt
new file mode 100644
index 00000000000..a83e2c15f3c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/valueFromJava.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(List<Object> x) {}
+    List<String> bar() {}
+}
+// FILE: main.kt
+
+fun main(a: A) {
+    a.foo(a.bar())
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/wildcards.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/wildcards.fir.kt
new file mode 100644
index 00000000000..844dc40d09a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/genericVarianceViolation/wildcards.fir.kt
@@ -0,0 +1,49 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A {
+    void foo(List<?> x) {}
+    void foo(Iterable<?> x) {}
+    void foo(Iterator<?> x) {}
+    void foo(Set<?> x) {}
+    void foo(Map<?, ?> x) {}
+    void foo(Map.Entry<?, ?> x) {}
+}
+
+// FILE: main.kt
+
+fun main(
+        a: A,
+        ml: MutableList<String>, l: List<String>,
+        ms: MutableSet<String>, s: Set<String>,
+        mm: MutableMap<Any, String>, m: Map<Any, String>,
+        mme: MutableMap.MutableEntry<Any, String>, me: Map.Entry<Any, String>
+) {
+    // Lists
+    a.foo(ml)
+    a.foo(l)
+
+    // Iterables
+    val mit: MutableIterable<String> = ml
+    val it: Iterable<String> = ml
+    a.foo(mit)
+    a.foo(it)
+
+    // Iterators
+    a.foo(ml.iterator())
+    a.foo(l.iterator())
+
+    // Sets
+    a.foo(ms)
+    a.foo(s)
+
+    // Maps
+    a.foo(mm)
+    a.foo(m)
+
+    // Map entries
+    a.foo(mme)
+    a.foo(me)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/getParentOfType.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/getParentOfType.fir.kt
new file mode 100644
index 00000000000..298c74ab12a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/getParentOfType.fir.kt
@@ -0,0 +1,36 @@
+// FILE: p/PsiElement.java
+
+package p;
+
+public interface PsiElement {}
+
+// FILE: p/JetExpression.java
+
+package p;
+
+public interface JetExpression extends PsiElement {}
+
+// FILE: p/Util.java
+
+package p;
+
+public class Util {
+
+    public static <T extends PsiElement> T getParentOfType(@Nullable PsiElement element, @NotNull Class<T> aClass) {
+        return null;
+    }
+
+    public static void on(JetExpression e) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(e: JetExpression) {
+    Util.on(
+        Util.getParentOfType(e, javaClass<JetExpression>()) ?: e
+    )
+}
+
+fun <T> javaClass(): Class<T> = null!!
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/inference.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/inference.fir.kt
new file mode 100644
index 00000000000..ea06d3c395c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/inference.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+
+// FILE: foo/Base.java
+
+package foo;
+
+public interface Base<T> {}
+
+// FILE: foo/HS.java
+
+package foo;
+
+public class HS<T> extends Base<T> {}
+
+// FILE: k.kt
+
+import foo.*;
+
+fun <T, C: Base<T>> convert(src: HS<T>, dest: C): C = throw Exception("$src $dest")
+
+fun test(l: HS<Int>) {
+    //todo should be inferred
+    val r = convert(l, HS())
+    r checkType { <!UNRESOLVED_REFERENCE!>_<!><HS<Int>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/intVsIntegerAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/intVsIntegerAmbiguity.fir.kt
new file mode 100644
index 00000000000..0e13d7b542d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/intVsIntegerAmbiguity.fir.kt
@@ -0,0 +1,37 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public interface A {}
+    public static A foo(int s);
+
+    public interface B {}
+    public static B foo(Integer s);
+
+    public static Integer getInteger();
+}
+
+// FILE: k.kt
+
+import p.*
+import p.J.*
+
+class C
+
+fun foo(i: Int?) : C = null!!
+
+fun test(i: Int, ni: Int?) {
+    checkSubtype<C>(foo(2))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><J.A>(J.<!AMBIGUITY!>foo<!>(2))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><J.A>(J.<!AMBIGUITY!>foo<!>(i))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><J.B>(J.<!AMBIGUITY!>foo<!>(ni))
+    checkSubtype<C>(foo(ni))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><J.B>(J.<!AMBIGUITY!>foo<!>(ni))
+
+    foo(J.getInteger())
+    J.<!AMBIGUITY!>foo<!>(J.getInteger())
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/intersection/map.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/intersection/map.fir.kt
new file mode 100644
index 00000000000..5edcc2d090d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/intersection/map.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+// !EXPLICIT_FLEXIBLE_TYPES
+
+fun foo(
+        p1: ft<MutableMap<Int, String>, Map<Int, String>?>,
+        p2: Map<Int, String>
+) = p1 == p2
+
+fun foo(
+        p1: ft<String, String?>,
+        p2: String
+) = p1 == p2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/javaEmptyList.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/javaEmptyList.fir.kt
new file mode 100644
index 00000000000..a31eb896c2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/javaEmptyList.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+
+// FILE: Collections.java
+import java.util.List;
+
+public class Collections {
+    public static final <T> List<T> emptyList() {
+        return null;
+    }
+}
+
+// FILE: 1.kt
+
+fun bar(): List<String> = null!!
+
+fun test() {
+    val f = if (true) {
+        Collections.emptyList()
+    }
+    else {
+        bar()
+    }
+
+    checkSubtype<List<String>>(f)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/entrySet.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/entrySet.fir.kt
new file mode 100644
index 00000000000..3aaf4cce6e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/entrySet.fir.kt
@@ -0,0 +1,24 @@
+// FILE: p/MultiMap.java
+
+package p;
+
+import java.util.*;
+
+public class MultiMap<K, V> {
+    public Set<Collection<V>> entrySet() {
+        return null;
+    }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test() {
+    val map = MultiMap<Int, String>()
+    val set = map.entrySet()
+    set.iterator()
+
+    val set1 = map.entrySet()!!
+    set1.iterator()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/genericsAndArrays.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/genericsAndArrays.fir.kt
new file mode 100644
index 00000000000..143f5c4cd89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/genericsAndArrays.fir.kt
@@ -0,0 +1,24 @@
+// FILE: p/J.java
+
+package p;
+
+public class J<T> {
+    public void foo(Ref<T[]> r) {}
+}
+
+// FILE: p/Ref.java
+
+package p;
+
+public class Ref<T> {
+    public static <T> Ref<T> create() { return null; }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun main(j: J<String>) {
+    val r = Ref.create<Array<String>>()
+    j.foo(r)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/int.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/int.fir.kt
new file mode 100644
index 00000000000..cfcf3e01468
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/int.fir.kt
@@ -0,0 +1,16 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public void _int(int s) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test() {
+    J()._int(1)
+    J()._int(null)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/intArray.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/intArray.fir.kt
new file mode 100644
index 00000000000..d79113f9023
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/intArray.fir.kt
@@ -0,0 +1,16 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public void intArr(int[] s) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(ia: IntArray) {
+    J().intArr(ia)
+    J().intArr(null)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaCollectionToKotlin.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaCollectionToKotlin.fir.kt
new file mode 100644
index 00000000000..fa1baddc8f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaCollectionToKotlin.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import java.util.*
+
+fun takeJ(map: Map<Any, Any>) {}
+
+fun test() {
+    takeJ(HashMap())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToJava.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToJava.fir.kt
new file mode 100644
index 00000000000..cbd9d0da968
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToJava.fir.kt
@@ -0,0 +1,20 @@
+// FILE: p/J.java
+
+package p;
+
+import java.util.ArrayList;
+
+public class J {
+    public ArrayList<String> list() { return null; }
+    public void takeList(ArrayList<String> list) { }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(j: J) {
+    j.takeList(j.list())
+    val l = j.list()
+    j.takeList(l)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToKotlin.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToKotlin.fir.kt
new file mode 100644
index 00000000000..e454e5b2dca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToKotlin.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public J j() { return this; }
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun takeJ(j: J) {}
+
+fun test() {
+    takeJ(J().j())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/kotlinCollectionToJava.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/kotlinCollectionToJava.fir.kt
new file mode 100644
index 00000000000..d08d6cf52fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/kotlinCollectionToJava.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import java.util.*
+
+fun test(map: Map<Any, Any>) {
+    HashMap(map)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/kt27565.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/kt27565.fir.kt
new file mode 100644
index 00000000000..8edd7891956
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/kt27565.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// ISSUE: KT-27565
+
+// FILE: Runnable.java
+
+public interface Runnable {
+    void run();
+}
+
+// FILE: k.kt
+
+fun fail() {
+    <!AMBIGUITY!>foo<!>({ }, { })
+    <!AMBIGUITY!>foo<!>(::bar, { })
+}
+
+fun foo(f: Runnable, selector: () -> Unit) {}
+fun foo(func1: () -> Unit, func2: () -> Unit) {}
+
+fun bar() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/list.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/list.fir.kt
new file mode 100644
index 00000000000..a1f4cf524f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/list.fir.kt
@@ -0,0 +1,18 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public void list(java.util.List<String> s) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(ls: List<String>, mls: MutableList<String>, lsn: List<String?>, mlsn: MutableList<String?>?) {
+    J().list(ls)
+    J().list(mls)
+    J().list(lsn)
+    J().list(mlsn)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/multipleExactBounds.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/multipleExactBounds.fir.kt
new file mode 100644
index 00000000000..daa89b278a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/multipleExactBounds.fir.kt
@@ -0,0 +1,21 @@
+import java.util.HashMap
+
+interface ModuleDescriptorImpl
+interface ModuleInfo
+interface ResolverForModule
+interface ResolverForProject<M1, R1>
+
+class ResolverForProjectImpl<M : ModuleInfo, R : ResolverForModule>(
+        descriptorByModule: Map<M, ModuleDescriptorImpl>,
+        delegateResolver: ResolverForProject<M, R>
+) : ResolverForProject<M, R>
+
+fun <M2: ModuleInfo, A: ResolverForModule> foo(delegateResolver: ResolverForProject<M2, A>): ResolverForProject<M2, A> {
+    val descriptorByModule = HashMap<M2, ModuleDescriptorImpl>()
+    return ResolverForProjectImpl(descriptorByModule, delegateResolver)
+}
+
+// M = M2
+// HashMap<M2, MDI> :< Map<M, MDI> => M = M2!
+// R = A
+// RFP<M2, A> :< RFP<M, R>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/multipleExactBoundsNullable.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/multipleExactBoundsNullable.fir.kt
new file mode 100644
index 00000000000..73eb3d69552
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/multipleExactBoundsNullable.fir.kt
@@ -0,0 +1,39 @@
+// JAVAC_EXPECTED_FILE
+// FILE: MyMap.java
+
+import java.util.AbstractMap;
+import java.util.Set;
+
+class MyMap<K, V> extends AbstractMap<K, V> {
+    @Override
+    public Set<Entry<K, V>> entrySet() {
+        return null;
+    }
+}
+
+// FILE: main.kt
+
+interface ResolverForProject<M1> {
+    val exposeM: M1 get() = null!!
+}
+
+class ResolverForProjectImpl<M>(
+        descriptorByModule: Map<M, String>,
+        delegateResolver: ResolverForProject<M>
+) : ResolverForProject<M>
+
+interface WithFoo {
+    fun foo()
+}
+
+fun <M2: WithFoo> foo(delegateResolver: ResolverForProject<M2?>): ResolverForProject<M2?> {
+    val descriptorByModule = MyMap<M2, String>()
+    val result = <!INAPPLICABLE_CANDIDATE!>ResolverForProjectImpl<!>(descriptorByModule, delegateResolver)
+    result.<!UNRESOLVED_REFERENCE!>exposeM<!>.<!UNRESOLVED_REFERENCE!>foo<!>() // M is not M2?
+    result.<!UNRESOLVED_REFERENCE!>exposeM<!>?.<!UNRESOLVED_REFERENCE!>foo<!>() // no warning, M is not M2, hense M is M2!
+
+    return <!INAPPLICABLE_CANDIDATE!>ResolverForProjectImpl<!>(descriptorByModule, delegateResolver) // another bound check
+}
+
+// MyMap<M2, String> :< Map<M, String> => M = M2!
+// RFP<M2?> :< RFP<M> => M = M2?
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/objectArray.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/objectArray.fir.kt
new file mode 100644
index 00000000000..64ac5f084cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/objectArray.fir.kt
@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public void arr(Object[] s) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(
+        aa: Array<Any>,
+        sa: Array<String>,
+        san: Array<String?>
+) {
+    J().arr(null)
+    J().arr(aa)
+    J().arr(sa)
+    J().arr(san)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/overloadingForSubclass.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/overloadingForSubclass.fir.kt
new file mode 100644
index 00000000000..d15ca76f0a5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/overloadingForSubclass.fir.kt
@@ -0,0 +1,30 @@
+// FILE: p/Super.java
+package p;
+
+public interface Super {}
+
+// FILE: p/Sub.java
+package p;
+
+public interface Sub extends Super {}
+
+// FILE: p/Util.java
+
+package p;
+
+public abstract class Util {
+    public abstract void foo(String s, Super sup);
+    public void foo(String s, Sub sub) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+class C: Util() {
+    override fun foo(s: String, sub: Super) {}
+}
+
+fun foo(sub: Sub) {
+    C().foo("", sub)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/sam.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/sam.fir.kt
new file mode 100644
index 00000000000..ed1b08ed76a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/sam.fir.kt
@@ -0,0 +1,26 @@
+// FILE: p/SAM.java
+
+package p;
+
+public interface SAM<R> {
+    R foo();
+}
+
+// FILE: p/Util.java
+
+package p;
+
+public class Util {
+
+    public static void sam(SAM<Void> sam) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test() {
+    Util.sam {
+        null
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/singleton.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/singleton.fir.kt
new file mode 100644
index 00000000000..395fbdddb07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/singleton.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+interface Foo
+
+fun test() {
+    var nullable: Foo? = null
+    val foo: Collection<Foo> = java.util.Collections.singleton(nullable)
+    val foo1: Collection<Foo> = java.util.Collections.singleton(nullable!!)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/string.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/string.fir.kt
new file mode 100644
index 00000000000..1b0f1370754
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/string.fir.kt
@@ -0,0 +1,16 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public void str(J s) {}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test() {
+    J().str(J())
+    J().str(null)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodCall/visitor.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodCall/visitor.fir.kt
new file mode 100644
index 00000000000..ee932531ddb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodCall/visitor.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// FILE: p/Visitor.java
+
+package p;
+
+public interface Visitor<D> {
+
+}
+
+// FILE: p/Element.java
+
+package p;
+
+import org.jetbrains.annotations.NotNull;
+
+public class Element {
+    public <D, R> R accept(@NotNull Visitor<R> visitor, D data) {return null;}
+}
+
+// FILE: k.kt
+
+import p.*
+
+fun test(v: Visitor<Nothing>, e: Element) {
+    e.accept(v, null)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/methodTypeParameterDefaultBound.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/methodTypeParameterDefaultBound.fir.kt
new file mode 100644
index 00000000000..2d3b7398878
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/methodTypeParameterDefaultBound.fir.kt
@@ -0,0 +1,25 @@
+// FILE: Derived.java
+import kotlin.jvm.functions.Function0;
+import org.jetbrains.annotations.NotNull;
+
+public class Derived implements Base {
+    @Override
+    public <V> void foo() {}
+}
+
+// FILE: main.kt
+interface Base {
+    fun <V: Any> foo()
+}
+
+class KotlinDerived1 : Derived() {
+    override fun <V: Any?> foo() {}
+}
+
+class KotlinDerived2 : Derived() {
+    override fun <V: Any> foo() {}
+}
+
+fun main() {
+    Derived().foo<String>()
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/noAnnotationInClassPath.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/noAnnotationInClassPath.fir.kt
new file mode 100644
index 00000000000..de64ac8a435
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/noAnnotationInClassPath.fir.kt
@@ -0,0 +1,17 @@
+// FILE: A.java
+
+// It's supposed that there is no JSR-305 annotation in classpath
+public interface A<T> {
+    public boolean foo(@javax.annotation.Nullable T y) {}
+}
+
+// FILE: B.java
+
+public class B {
+    public static void bar(A<String> y) {}
+}
+
+// FILE: main.kt
+fun test() {
+    B.bar() { it.<!INAPPLICABLE_CANDIDATE!>hashCode<!>() > 0 }
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/enhancementFromAnnotation.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/enhancementFromAnnotation.fir.kt
new file mode 100644
index 00000000000..59a9fc1f575
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/enhancementFromAnnotation.fir.kt
@@ -0,0 +1,28 @@
+// FILE: A.java
+
+import org.jetbrains.annotations.NotNull;
+public interface A<T> {
+    void foo(@NotNull T x);
+}
+
+// FILE: B.java
+public class B<E> {
+    public void foo(E x) {}
+}
+
+// FILE: C.java
+public class C<F> extends B<F> implements A<F> {
+    public static C<String> create() { return null; }
+    public void foo(F x) {}
+}
+
+// FILE: main.kt
+
+fun test() {
+    C.create().foo(null)
+    C.create().foo("")
+
+    C<String>().foo(null)
+    C<String?>().foo(null)
+    C<String?>().foo("")
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/enhancementFromKotlin.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/enhancementFromKotlin.fir.kt
new file mode 100644
index 00000000000..c86b1711a17
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/enhancementFromKotlin.fir.kt
@@ -0,0 +1,28 @@
+// FILE: A.kt
+
+import org.jetbrains.annotations.NotNull;
+public interface A<T> {
+    fun foo(x: T)
+}
+
+// FILE: B.java
+public class B<E> {
+    public void foo(E x) {}
+}
+
+// FILE: C.java
+public class C<F> extends B<F> implements A<F> {
+    public static C<String> create() { return null; }
+    public void foo(F x) {}
+}
+
+// FILE: main.kt
+
+fun test() {
+    C.create().foo(null)
+    C.create().foo("")
+
+    C<String>().foo(null)
+    C<String?>().foo(null)
+    C<String?>().foo("")
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/methodTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/methodTypeParameter.fir.kt
new file mode 100644
index 00000000000..689e6e31ab5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/methodTypeParameter.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// FILE: A.java
+
+import org.jetbrains.annotations.NotNull;
+
+public class A {
+    public static <T> void bar(@NotNull T x, T y) { }
+    public static String platformString() { return null; }
+}
+
+// FILE: k.kt
+
+fun test() {
+    A.bar(null, "")
+
+    A.bar<String>(null, "")
+    A.bar<String?>(null, "")
+    A.bar(null, A.platformString())
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/noInheritanceReturnType.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/noInheritanceReturnType.fir.kt
new file mode 100644
index 00000000000..9e558217c08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/noInheritanceReturnType.fir.kt
@@ -0,0 +1,23 @@
+// FILE: A.java
+
+import java.util.*;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class A<T> {
+    public static A<String> create() {
+        return null;
+    }
+
+    @NotNull
+    public T bar() {
+    }
+}
+
+// FILE: k.kt
+
+fun test() {
+    A.create().bar()?.length
+    A<String?>().bar()?.length
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/noInheritanceValueParameter.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/noInheritanceValueParameter.fir.kt
new file mode 100644
index 00000000000..833b6ecaab4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/noInheritanceValueParameter.fir.kt
@@ -0,0 +1,26 @@
+// FILE: A.java
+
+import java.util.*;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class A<T> {
+    public static A<String> create() {
+        return null;
+    }
+
+    public void bar(@NotNull T x) {
+    }
+}
+
+// FILE: k.kt
+
+fun test() {
+    A.create().bar(null)
+    A.create().bar("")
+
+    A<String>().bar(null)
+    A<String?>().bar(null)
+    A<String?>().bar("")
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/onTypeProjection.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/onTypeProjection.fir.kt
new file mode 100644
index 00000000000..e0269c09835
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/onTypeProjection.fir.kt
@@ -0,0 +1,19 @@
+// FILE: A.java
+
+import java.util.*;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class A<T> {
+    @NotNull
+    public T bar() {
+    }
+}
+
+// FILE: k.kt
+
+fun test(a: A<out CharSequence>) {
+    a.bar()?.length
+    a.bar()?.length
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/substitutionInSuperType.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/substitutionInSuperType.fir.kt
new file mode 100644
index 00000000000..7027ad2ac42
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/notNullTypeParameter/substitutionInSuperType.fir.kt
@@ -0,0 +1,41 @@
+// FILE: A.java
+
+import java.util.*;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class A<T> {
+    public void bar(@NotNull T x) {
+    }
+}
+
+// FILE: B1.java
+public class B1 extends A<String> {
+    // real override
+    public void bar(String x) {
+    }
+}
+
+// FILE: B2.java
+public class B2 extends A<String> {
+    // fake override bar
+}
+
+// FILE: k.kt
+
+class C1 : A<String?>() {
+    override fun bar(x: String) {}
+}
+
+class C2 : A<String?>() {
+    override fun bar(x: String?) {}
+}
+
+fun test() {
+    B1().bar(null)
+    B2().bar(null)
+
+    C1().<!AMBIGUITY!>bar<!>(null)
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/arithmetic.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/arithmetic.fir.kt
new file mode 100644
index 00000000000..9bced64c4a5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/arithmetic.fir.kt
@@ -0,0 +1,55 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static Integer staticNN;
+    @Nullable
+    public static Integer staticN;
+    public static Integer staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    var platformNN = J.staticNN
+    // @Nullable platform type
+    var platformN = J.staticN
+    // platform type with no annotation
+    var platformJ = J.staticJ
+
+    +platformNN
+    <!INAPPLICABLE_CANDIDATE!>+<!>platformN
+    +platformJ
+
+    ++platformNN
+    <!INAPPLICABLE_CANDIDATE!>++<!>platformN
+    ++platformJ
+
+    platformNN++
+    platformN++
+    platformJ++
+
+    1 + platformNN
+    1 + platformN
+    1 + platformJ
+
+    platformNN + 1
+    platformN + 1
+    platformJ + 1
+
+    1 plus platformNN
+    1 plus platformN
+    1 plus platformJ
+
+    platformNN plus 1
+    platformN plus 1
+    platformJ plus 1
+
+    platformNN += 1
+    platformN += 1
+    platformJ += 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/array.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/array.fir.kt
new file mode 100644
index 00000000000..6947757570d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/array.fir.kt
@@ -0,0 +1,31 @@
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static Integer[] staticNN;
+    @Nullable
+    public static Integer[] staticN;
+    public static Integer[] staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    platformNN[0]
+    platformN[0]
+    platformJ[0]
+
+    platformNN[0] = 1
+    platformN[0]  = 1
+    platformJ[0]  = 1
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/assignToVar.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/assignToVar.fir.kt
new file mode 100644
index 00000000000..0bd4993ff8e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/assignToVar.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+var v: J = J()
+var n: J? = J()
+
+fun test() {
+    v = J.staticNN
+    v = J.staticN
+    v = J.staticJ
+
+    n = J.staticNN
+    n = J.staticN
+    n = J.staticJ
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/conditions.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/conditions.fir.kt
new file mode 100644
index 00000000000..b81312ebbed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/conditions.fir.kt
@@ -0,0 +1,48 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static Boolean staticNN;
+    @Nullable
+    public static Boolean staticN;
+    public static Boolean staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    if (platformNN) {}
+    if (platformN) {}
+    if (platformJ) {}
+
+    while (platformNN) {}
+    while (platformN) {}
+    while (platformJ) {}
+
+    do {} while (platformNN)
+    do {} while (platformN)
+    do {} while (platformJ)
+
+    platformNN && false
+    platformN && false
+    platformJ && false
+
+    platformNN || false
+    platformN || false
+    platformJ || false
+
+    !platformNN
+    <!INAPPLICABLE_CANDIDATE!>!<!>platformN
+    !platformJ
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/dataFlowInfo.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/dataFlowInfo.fir.kt
new file mode 100644
index 00000000000..83f6b64ec77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/dataFlowInfo.fir.kt
@@ -0,0 +1,32 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+}
+
+// FILE: k.kt
+
+fun test() {
+    val n = J.staticN
+    foo(n)
+    J.staticNN = n
+    if (n != null) {
+        foo(n)
+        J.staticNN = n
+    }
+
+    val x: J? = null
+    J.staticNN = x
+    if (x != null) {
+        J.staticNN = x
+    }
+}
+
+fun foo(j: J) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/defaultParameters.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/defaultParameters.fir.kt
new file mode 100644
index 00000000000..1ef043f66e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/defaultParameters.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    fun foo(p: J = platformNN, p1: J = platformN, p2: J = platformJ) {}
+
+    fun foo1(p: J? = platformNN, p1: J? = platformN, p2: J? = platformJ) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/delegatedProperties.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/delegatedProperties.fir.kt
new file mode 100644
index 00000000000..fae7807c753
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/delegatedProperties.fir.kt
@@ -0,0 +1,23 @@
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+
+    public interface DP {
+        String getValue(Object a, Object b);
+        String setValue(Object a, Object b, Object c);
+    }
+
+    @NotNull
+    public static DP staticNN;
+    @Nullable
+    public static DP staticN;
+    public static DP staticJ;
+}
+
+// FILE: k.kt
+
+var A by J.staticNN
+var B by J.staticN
+var C by J.staticJ
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/delegation.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/delegation.fir.kt
new file mode 100644
index 00000000000..2a16ec3d803
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/delegation.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+import java.util.*;
+
+public class J {
+    @NotNull
+    public static List<String> staticNN;
+    @Nullable
+    public static List<String> staticN;
+    public static List<String> staticJ;
+}
+
+// FILE: k.kt
+
+class A : List<String> by J.staticNN
+class B : List<String> by J.staticN
+class C : List<String> by J.staticJ
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/derefenceExtension.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/derefenceExtension.fir.kt
new file mode 100644
index 00000000000..413bcb99789
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/derefenceExtension.fir.kt
@@ -0,0 +1,45 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    platformNN.foo()
+    platformN.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    platformJ.foo()
+
+    with(platformNN) {
+        foo()
+    }
+    with(platformN) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>()
+    }
+    with(platformJ) {
+        foo()
+    }
+
+    platformNN.bar()
+    platformN.bar()
+    platformJ.bar()
+}
+
+fun J.foo() {}
+fun J?.bar() {}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/derefenceMember.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/derefenceMember.fir.kt
new file mode 100644
index 00000000000..16310cc8fb5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/derefenceMember.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+
+    public void foo() {}
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    platformNN.foo()
+    platformN.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    platformJ.foo()
+
+    with(platformNN) {
+        foo()
+    }
+    with(platformN) {
+        foo()
+    }
+    with(platformJ) {
+        foo()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/elvis.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/elvis.fir.kt
new file mode 100644
index 00000000000..85fd8105cea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/elvis.fir.kt
@@ -0,0 +1,67 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -SENSELESS_COMPARISON, -UNUSED_PARAMETER
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+
+    public static <T> T getAny() {
+        return null;
+    }
+
+    @NotNull
+    public static <T> T getNNAny() {
+        return (T) null;
+    }
+
+    @Nullable
+    public static <T> T getNAny() {
+        return null;
+    }
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    val v0 = platformNN ?: J()
+    platformNN ?: J()
+    platformN ?: J()
+    platformJ ?: J()
+
+    if (platformNN != null) {
+        platformNN ?: J()
+    }
+
+    if (platformN != null) {
+        platformN ?: J()
+    }
+
+    if (platformJ != null) {
+        platformJ ?: J()
+    }
+
+    takeNotNull(J.staticNN ?: J())
+    takeNotNull(J.staticN ?: J())
+    takeNotNull(J.staticJ ?: J())
+    takeNotNull(J.getAny() ?: J())
+    takeNotNull(J.getNNAny() ?: J())
+    takeNotNull(J.getNAny() ?: J())
+
+    val x = <!UNRESOLVED_REFERENCE!>unresolved<!> ?: null
+    val y = <!UNRESOLVED_REFERENCE!>unresolved<!>.<!UNRESOLVED_REFERENCE!>foo<!> ?: return
+}
+
+fun takeNotNull(s: J) {}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/expectedType.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/expectedType.fir.kt
new file mode 100644
index 00000000000..4cb1e8e3926
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/expectedType.fir.kt
@@ -0,0 +1,32 @@
+// !CHECK_TYPE
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    checkSubtype<J>(platformNN)
+    checkSubtype<J>(platformN)
+    checkSubtype<J>(platformJ)
+
+    checkSubtype<J?>(platformNN)
+    checkSubtype<J?>(platformN)
+    checkSubtype<J?>(platformJ)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/for.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/for.fir.kt
new file mode 100644
index 00000000000..85fe29d1472
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/for.fir.kt
@@ -0,0 +1,28 @@
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+import java.util.*;
+
+public class J {
+    @NotNull
+    public static List<String> staticNN;
+    @Nullable
+    public static List<String> staticN;
+    public static List<String> staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    for (x in platformNN) {}
+    <!INAPPLICABLE_CANDIDATE, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (x in platformN) {}<!>
+    for (x in platformJ) {}
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/functionArguments.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/functionArguments.fir.kt
new file mode 100644
index 00000000000..981585397c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/functionArguments.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    foo(J.staticNN)
+    foo(J.staticN)
+    foo(J.staticJ)
+
+    bar(J.staticNN)
+    bar(J.staticN)
+    bar(J.staticJ)
+}
+
+fun foo(j: J) {}
+fun bar(j: J?) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/inferenceInConditionals.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/inferenceInConditionals.fir.kt
new file mode 100644
index 00000000000..fe37a7510fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/inferenceInConditionals.fir.kt
@@ -0,0 +1,27 @@
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+import java.util.*;
+
+public class J {
+    @NotNull
+    public String nn() { return ""; }
+
+    @Nullable
+    public List<String> n() { return null; }
+}
+
+// FILE: k.kt
+
+fun safeCall(c: J?) {
+  c?.nn()?.length
+}
+
+fun ifelse(c: J): Any? {
+    return if (true) c.nn() else null
+}
+
+fun elvis(c: J): Any? {
+    return null ?: c.nn()
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/invoke.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/invoke.fir.kt
new file mode 100644
index 00000000000..cd541506a09
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/invoke.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    public interface Invoke {
+        void invoke();
+    }
+
+    @NotNull
+    public static Invoke staticNN;
+    @Nullable
+    public static Invoke staticN;
+    public static Invoke staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    J.staticNN()
+    J.<!INAPPLICABLE_CANDIDATE!>staticN<!>()
+    J.staticJ()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/kt6829.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/kt6829.fir.kt
new file mode 100644
index 00000000000..356e46c7d01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/kt6829.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// KT-6829 False warning on map to @Nullable
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+
+    @Nullable
+    public String method() { return ""; }
+}
+
+// FILE: k.kt
+
+fun foo(collection: Collection<J>) {
+    val mapped = collection.map { it.method() }
+    mapped[0].<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+public fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> {
+    null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/multiDeclaration.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/multiDeclaration.fir.kt
new file mode 100644
index 00000000000..c997080cc1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/multiDeclaration.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    public interface Multi {
+        String component1();
+        String component2();
+    }
+
+    @NotNull
+    public static Multi staticNN;
+    @Nullable
+    public static Multi staticN;
+    public static Multi staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    val (a1, b1) = platformNN
+    val (<!INAPPLICABLE_CANDIDATE!>a2<!>, <!INAPPLICABLE_CANDIDATE!>b2<!>) = platformN
+    val (a3, b3) = platformJ
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/noWarningOnDoubleElvis.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/noWarningOnDoubleElvis.fir.kt
new file mode 100644
index 00000000000..e9891546877
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/noWarningOnDoubleElvis.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test() {
+    take(nullable() ?: nullable() ?: "foo")
+}
+
+fun <T> nullable(): T? = TODO()
+fun take(x: Any) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAfterSafeCall.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAfterSafeCall.fir.kt
new file mode 100644
index 00000000000..420dc45a990
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAfterSafeCall.fir.kt
@@ -0,0 +1,16 @@
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    public @NotNull String nn() { return ""; }
+}
+
+// FILE: k.kt
+
+fun test(j: J?) {
+    val s = j?.nn()
+    if (s != null) {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAssertion.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAssertion.fir.kt
new file mode 100644
index 00000000000..c388c511f33
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAssertion.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -SENSELESS_COMPARISON -UNUSED_PARAMETER
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    if (platformNN != null) {
+        platformNN!!
+    }
+
+    if (platformN != null) {
+        platformN!!
+    }
+
+    if (platformJ != null) {
+        platformJ!!
+    }
+
+    platformNN!!
+    platformN!!
+    platformJ!!
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAssertionInCall.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAssertionInCall.fir.kt
new file mode 100644
index 00000000000..51129def4ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullAssertionInCall.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+
+    foo(platformNN!!)
+    val bar = Bar()
+    bar(platformNN!!)
+}
+
+fun foo(a: Any) {}
+
+class Bar {
+    operator fun invoke(a: Any) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullTypeMarkedWithNullableAnnotation.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullTypeMarkedWithNullableAnnotation.fir.kt
new file mode 100644
index 00000000000..5e68aea15f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/notNullTypeMarkedWithNullableAnnotation.fir.kt
@@ -0,0 +1,22 @@
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+import java.util.*;
+
+public class J {
+    @Nullable
+    public List<String> n() { return null; }
+}
+
+// FILE: k.kt
+
+fun list(j: J): Any {
+    val a = j.n()!!
+
+    a?.get(0)
+    if (a == null) {}
+    a!!
+
+    a.get(0)
+    return a
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/passToJava.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/passToJava.fir.kt
new file mode 100644
index 00000000000..280455894df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/passToJava.fir.kt
@@ -0,0 +1,90 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+
+    public static void staticSet(@NotNull J nn, @Nullable J n, J j) {}
+
+    public J(@NotNull J nn, @Nullable J n, J j) {}
+    public J() {}
+
+    @NotNull
+    public J nn;
+    @Nullable
+    public J n;
+    public J j;
+
+    public void set(@NotNull J nn, @Nullable J n, J j) {}
+}
+
+// FILE: k.kt
+
+fun test(n: J?, nn: J) {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    J.staticNN = n
+    J.staticNN = platformN
+    J.staticNN = nn
+    J.staticNN = platformNN
+    J.staticNN = platformJ
+
+    J.staticN = n
+    J.staticN = platformN
+    J.staticN = nn
+    J.staticN = platformNN
+    J.staticN = platformJ
+
+    J.staticJ = n
+    J.staticJ = platformN
+    J.staticJ = nn
+    J.staticJ = platformNN
+    J.staticJ = platformJ
+
+    J.staticSet(nn, nn, nn)
+    J.staticSet(platformNN, platformNN, platformNN)
+    J.staticSet(n, n, n)
+    J.staticSet(platformN, platformN, platformN)
+    J.staticSet(platformJ, platformJ, platformJ)
+
+    J().nn = n
+    J().nn = platformN
+    J().nn = nn
+    J().nn = platformNN
+    J().nn = platformJ
+
+    J().n = n
+    J().n = platformN
+    J().n = nn
+    J().n = platformNN
+    J().n = platformJ
+
+    J().j = n
+    J().j = platformN
+    J().j = nn
+    J().j = platformNN
+    J().j = platformJ
+
+    J().set(nn, nn, nn)
+    J().set(platformNN, platformNN, platformNN)
+    J().set(n, n, n)
+    J().set(platformN, platformN, platformN)
+    J().set(platformJ, platformJ, platformJ)
+
+    J(nn, nn, nn)
+    J(platformNN, platformNN, platformNN)
+    J(n, n, n)
+    J(platformN, platformN, platformN)
+    J(platformJ, platformJ, platformJ)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/primitiveArray.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/primitiveArray.fir.kt
new file mode 100644
index 00000000000..9821a82d704
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/primitiveArray.fir.kt
@@ -0,0 +1,31 @@
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static int[] staticNN;
+    @Nullable
+    public static int[] staticN;
+    public static int[] staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    platformNN[0]
+    platformN[0]
+    platformJ[0]
+
+    platformNN[0] = 1
+    platformN[0]  = 1
+    platformJ[0]  = 1
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/safeCall.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/safeCall.fir.kt
new file mode 100644
index 00000000000..6704268cb6d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/safeCall.fir.kt
@@ -0,0 +1,43 @@
+// !DIAGNOSTICS: -SENSELESS_COMPARISON
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+
+    public void foo() {}
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    platformNN?.foo()
+    platformN?.foo()
+    platformJ?.foo()
+
+    if (platformNN != null) {
+        platformNN?.foo()
+    }
+
+    if (platformN != null) {
+        platformN?.foo()
+    }
+
+    if (platformJ != null) {
+        platformJ?.foo()
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/senselessComparisonEquals.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/senselessComparisonEquals.fir.kt
new file mode 100644
index 00000000000..fff0b3bf8a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/senselessComparisonEquals.fir.kt
@@ -0,0 +1,42 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    val a: Any? = null
+
+    if (platformNN != null) {}
+    if (null != platformNN) {}
+    if (platformNN == null) {}
+    if (null == platformNN) {}
+
+    if (a != null && platformNN != a) {}
+
+    if (platformN != null) {}
+    if (platformN == null) {}
+    if (a == null && platformN == a) {}
+
+    if (platformJ != null) {}
+    if (platformJ == null) {}
+    if (a == null && platformJ == a) {}
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/senselessComparisonIdentityEquals.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/senselessComparisonIdentityEquals.fir.kt
new file mode 100644
index 00000000000..971328e16a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/senselessComparisonIdentityEquals.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+    @Nullable
+    public static J staticN;
+    public static J staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+    // @Nullable platform type
+    val platformN = J.staticN
+    // platform type with no annotation
+    val platformJ = J.staticJ
+
+    val a: Any? = null
+
+    if (platformNN !== null) {}
+    if (null !== platformNN) {}
+    if (platformNN === null) {}
+    if (null === platformNN) {}
+
+    if (platformN !== null) {}
+    if (platformN === null) {}
+    if (a === null && platformN === a) {}
+
+    if (platformJ !== null) {}
+    if (platformJ === null) {}
+    if (a === null && platformJ === a) {}
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/throw.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/throw.fir.kt
new file mode 100644
index 00000000000..2755f518ced
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/throw.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static Exception staticNN;
+    @Nullable
+    public static Exception staticN;
+    public static Exception staticJ;
+}
+
+// FILE: k.kt
+
+fun test() {
+    throw J.staticNN
+}
+
+fun test1() {
+    throw J.staticN
+}
+
+fun test2() {
+    throw J.staticJ
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/uselessElvisInCall.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/uselessElvisInCall.fir.kt
new file mode 100644
index 00000000000..d7d368057b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/uselessElvisInCall.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @NotNull
+    public static J staticNN;
+}
+
+// FILE: k.kt
+
+fun test() {
+    // @NotNull platform type
+    val platformNN = J.staticNN
+
+    foo(platformNN ?: "")
+
+    val bar = Bar()
+    bar(platformNN ?: "")
+}
+
+fun foo(a: Any) {}
+
+class Bar {
+    operator fun invoke(a: Any) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/uselessElvisRightIsNull.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/uselessElvisRightIsNull.fir.kt
new file mode 100644
index 00000000000..d3fa74464b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/uselessElvisRightIsNull.fir.kt
@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public class J {
+    @Nullable
+    public static J staticN;
+}
+
+// FILE: JJ.java
+
+public class JJ {
+    public static JJ staticNN;
+}
+
+// FILE: JJJ.java
+
+import org.jetbrains.annotations.*;
+
+public class JJJ {
+    @NotNull
+    public static JJJ staticNNN;
+}
+
+// FILE: k.kt
+
+fun test() {
+    val a = J.staticN ?: null
+    foo(a)
+    val b = JJ.staticNN ?: null
+    foo(b)
+    val c = JJJ.staticNNN ?: null
+    foo(c)
+}
+
+fun foo(a: Any?) {
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullableTypeArgument.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/nullableTypeArgument.fir.kt
new file mode 100644
index 00000000000..a1b02c34276
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullableTypeArgument.fir.kt
@@ -0,0 +1,9 @@
+import java.util.ArrayList
+
+fun foo() {
+    val list = ArrayList<String?>()
+
+    for (s in list) {
+        s.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/override.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/override.fir.kt
new file mode 100644
index 00000000000..bf7c372a64f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/override.fir.kt
@@ -0,0 +1,26 @@
+// FILE: p/I.java
+
+package p;
+
+import p.J.Param;
+
+public interface I {
+    String s();
+}
+
+// FILE: p/J.java
+
+package p;
+
+public class J implements I {
+    public String s() { return null; }
+}
+
+// FILE: k.kt
+import p.*
+
+fun test() {
+    val s = J().s()
+    s.get(0)
+    s!!.get(0)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawOverrides.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawOverrides.fir.kt
new file mode 100644
index 00000000000..6dab60f9d3d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawOverrides.fir.kt
@@ -0,0 +1,41 @@
+// FILE: A.java
+import java.util.*;
+public interface A<T> {
+    <E extends CharSequence> E foo(T x, List<? extends T> y);
+}
+
+// FILE: B.java
+import java.util.*;
+public interface B extends A {
+    @Override
+    public String foo(Object x, List y);
+}
+
+// FILE: C.java
+import java.util.*;
+public abstract class C {
+    <E extends CharSequence, F extends E> E bar(F x, List<Map<E, F>> y);
+}
+
+// FILE: D.java
+import java.util.*;
+public class D extends C {
+    @Override
+    public String bar(CharSequence x, List y) {
+        return null;
+    }
+}
+
+// FILE: main.kt
+
+class E : D(), B {
+    override fun foo(x: Any, y: List<Any?>): String = ""
+    override fun bar(x: CharSequence?, y: List<*>?): String = ""
+}
+
+class E2 : B {
+    override fun foo(x: Any, y: List<String?>): String = ""
+}
+
+
+class F : D()
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawSamOverrides.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawSamOverrides.fir.kt
new file mode 100644
index 00000000000..ce1dd6cabcd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawSamOverrides.fir.kt
@@ -0,0 +1,41 @@
+// (failed) attempt to reproduce exception in
+// http://stackoverflow.com/questions/42571812/unsupportedoperationexception-while-building-a-kotlin-project-in-idea
+
+// FILE: Fun.java
+public interface Fun<T> {
+    public void invoke(T x);
+}
+
+// FILE: A.java
+public interface A<T> {
+    public void foo(T x, Fun<? extends T> y);
+}
+
+// FILE: B.java
+public interface B extends A {
+    @Override
+    public void foo(Object x, Fun y);
+}
+
+// FILE: C.java
+public abstract class C {
+    public abstract <T> void bar(Fun<T> y);
+
+    public static <T> void aStaticMethod(T x, Fun<T> y) {}
+
+    public static abstract class D extends C {
+        @Override
+        public <T> void bar(Fun<T> y) {}
+
+        public static void aStaticMethod(Object x, Fun y) {}
+    }
+}
+
+// FILE: main.kt
+class E1 : C.D(), B {
+    override fun foo(x: Any, y: Fun<Any?>) {}
+}
+
+class E2 : B {
+    override fun foo(x: Any, y: Fun<String?>) {}
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/arrays.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/arrays.fir.kt
new file mode 100644
index 00000000000..f29a54568c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/arrays.fir.kt
@@ -0,0 +1,44 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A<T extends CharSequence, E> {
+    T[] charSequences;
+    Map<String, T>[] maps;
+    List<Double>[][] arraysOfLists;
+    E[][] arraysOfAny;
+
+    List<Double[]>[] erasedLists;
+}
+
+// FILE: Test.java
+
+class Test {
+    static class RawADerived extends A {}
+    static A rawAField = null;
+}
+
+// FILE: main.kt
+
+fun <T> arrayOf(): Array<T> = null!!
+
+fun main() {
+    val raw = Test.rawAField
+
+    raw.charSequences = arrayOf<String>()
+    raw.charSequences = arrayOf<Double>()
+
+    raw.maps = arrayOf<Map<Int, Int>>()
+    raw.maps = arrayOf<MutableMap<Int, Int>>()
+    raw.maps = arrayOf<List<String>>()
+
+    raw.arraysOfLists = arrayOf<Array<List<*>>>()
+    raw.arraysOfLists = arrayOf<List<String>>()
+    raw.arraysOfLists = arrayOf<Array<Array<String>>>()
+
+    raw.arraysOfAny = arrayOf<Array<Array<String>>>()
+
+    raw.erasedLists = arrayOf<List<String>>()
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/errorType.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/errorType.fir.kt
new file mode 100644
index 00000000000..594034d0c9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/errorType.fir.kt
@@ -0,0 +1,12 @@
+// FILE: A.java
+import java.util.*;
+
+public class A<T> {
+    public void foo(Err<String> x, List<String> y);
+}
+
+// FILE: B.java
+
+public class B extends A {
+
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/genericInnerClass.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/genericInnerClass.fir.kt
new file mode 100644
index 00000000000..8c109ee9e4c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/genericInnerClass.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+class A<T> {
+
+    void foo(T x) {}
+
+    public class Inner<E> {
+        Inner(E x0, T x, List<T> y) {}
+
+        void foo(E x0, T x, List<T> y) {}
+        A<Map<E, T>> bar() {}
+    }
+}
+
+// FILE: Test.java
+
+class Test {
+    static A rawAField = null;
+}
+
+// FILE: main.kt
+
+val strList: List<String> = null!!
+
+fun main() {
+    val rawA = Test.rawAField
+    var rawInner = rawA.<!INAPPLICABLE_CANDIDATE!>Inner<!><Double>("", "", strList)
+    rawInner.<!UNRESOLVED_REFERENCE!>foo<!>("", "", strList)
+    rawInner.<!UNRESOLVED_REFERENCE!>bar<!>().<!UNRESOLVED_REFERENCE!>foo<!>("")
+}
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/interClassesRecursion.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/interClassesRecursion.fir.kt
new file mode 100644
index 00000000000..a0351f21e5c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/interClassesRecursion.fir.kt
@@ -0,0 +1,4 @@
+// FILE: JavaScriptParser.java
+public class JavaScriptParser<F extends JSPsiTypeParser> {}
+// FILE: JSPsiTypeParser.java
+public class JSPsiTypeParser<T extends JavaScriptParser> {}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/nonGenericRawMember.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/nonGenericRawMember.fir.kt
new file mode 100644
index 00000000000..824d6553cd5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/nonGenericRawMember.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+class A<T> {
+    B b;
+}
+
+// FILE: B.java
+
+import java.util.*;
+
+class B {
+    void bar(List<Double> x);
+}
+
+// FILE: Test.java
+
+class Test {
+    static class RawADerived extends A {}
+    static A rawAField = null;
+}
+
+
+// FILE: main.kt
+
+val strList: List<String> = null!!
+
+fun main() {
+    val rawB = Test.rawAField.b;
+    // Raw(A).b is not erased because it have no type parameters
+    var rawInner = rawB.<!INAPPLICABLE_CANDIDATE!>bar<!>(<!UNRESOLVED_REFERENCE!>!<!>", "<!UNRESOLVED_REFERENCE!>List<!><!SYNTAX!><<!><!UNRESOLVED_REFERENCE!>String<!><!SYNTAX!>><!><!SYNTAX!><!>")!>strList)<!SYNTAX, SYNTAX!><!>
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/nonTrivialErasure.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/nonTrivialErasure.fir.kt
new file mode 100644
index 00000000000..eab6503afe8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/nonTrivialErasure.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+class A<T extends A<T, E>, E extends T, F extends List<? extends Double>> {
+    T first;
+    E second;
+    F listOfDoubles;
+}
+
+// FILE: Test.java
+
+class Test {
+    static class DerivedRawA extends A {}
+    static A rawAField = null;
+}
+
+// FILE: main.kt
+val strList: List<String> = null!!
+
+fun main() {
+    val rawA = Test.rawAField
+    rawA.first = Test.rawAField.second
+    Test.rawAField.second = rawA.first.<!INAPPLICABLE_CANDIDATE!>second<!>
+
+    rawA.listOfDoubles = strList
+    rawA.listOfDoubles = "" // first should be List
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawEnhancment.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawEnhancment.fir.kt
new file mode 100644
index 00000000000..302f3976a29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawEnhancment.fir.kt
@@ -0,0 +1,17 @@
+// FILE: B.java
+import java.util.List;
+
+public class B implements X {
+    @Override
+    List foo(List l) {
+        return super.foo(l);
+    }
+}
+
+// FILE: 1.kt
+
+interface X {
+    fun foo(l: MutableList<Int>): List<String>?
+}
+
+internal class C : B()
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawSupertype.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawSupertype.fir.kt
new file mode 100644
index 00000000000..9cb68995aa6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawSupertype.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+class A<T> {
+    List<T> x;
+
+    void foo(T x, List<T> y) {}
+
+    A<List<T>> bar() {}
+}
+
+// FILE: Test.java
+
+class Test {
+    static class RawADerived extends A {
+
+    }
+}
+
+// FILE: main.kt
+
+val strList: List<String> = null!!
+val strMap: Map<String, String> = null!!
+
+fun main() {
+    val rawADerived = Test.RawADerived()
+    rawADerived.x = strList
+    rawADerived.foo("", strList)
+
+
+    val rawA = rawADerived.bar()
+    rawA.x = strList
+    rawA.<!INAPPLICABLE_CANDIDATE!>foo<!>("", strList)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawSupertypeOverride.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawSupertypeOverride.fir.kt
new file mode 100644
index 00000000000..a2140ed2e02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawSupertypeOverride.fir.kt
@@ -0,0 +1,41 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A<T extends CharSequence> {
+    A<List<T>> foo(T x, Map<String, List<T>> y, HashMap<T, T> z) {}
+
+    void bar(List<Double[]>[][] d) {}
+}
+
+// FILE: RawADerived.java
+
+public class RawADerived extends A {
+}
+
+// FILE: main.kt
+import java.util.*;
+
+class B1 : RawADerived() {
+    override fun foo(x: CharSequence, y: Map<Any?, Any?>, z: HashMap<Any, Any>): A<*> = null!!
+
+    override fun bar(d: Array<Array<List<*>>>) {}
+}
+
+class B2 : RawADerived() {
+    override fun foo(x: CharSequence?, y: MutableMap<Any?, Any?>, z: HashMap<Any?, Any?>): A<String> = null!!
+
+    override fun bar(d: Array<Array<MutableList<*>>>) {}
+}
+
+class B3 : RawADerived() {
+    // Type of second parameter (y) is not equal to overridden
+    // RawADerived.foo.y --- (MutableMap<Any?, Any?>..Map<out Any?, out Any?>) is not a subtype of Map<Any?, Any>
+    override fun foo(x: CharSequence, y: Map<Any?, Any>, z: HashMap<Any, Any>): A<*> = null!!
+}
+
+class B4 : RawADerived() {
+    // Type of first parameter is not equal to overridden
+    override fun bar(d: Array<Array<MutableList<Array<Double>>>>) {}
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawTypeInUpperBound.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawTypeInUpperBound.fir.kt
new file mode 100644
index 00000000000..d6a67267f13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawTypeInUpperBound.fir.kt
@@ -0,0 +1,38 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.List;
+
+public class A<T> {
+    List<String> getChildrenStubs() { return null; }
+    void consume(T x) {}
+
+    T produce() { return null; }
+}
+
+// FILE: B.java
+
+public class B<E extends A> {
+    public E foo() { return null;}
+    E field;
+}
+
+// FILE: Test.java
+
+public class Test {
+    static B rawB = null;
+}
+
+// FILE: main.kt
+
+fun foo(x: B<*>) {
+    // TODO: x.foo() now is flexible type instead of raw, because of captured type approximation
+    val q: MutableList<String> = x.foo().<!INAPPLICABLE_CANDIDATE!>getChildrenStubs<!>()
+
+    // Raw(B).field erased to A<Any!>..A<out Any!>?
+    Test.rawB.field = A<String>()
+    val anyA: A<Any> = Test.rawB.field
+
+    Test.rawB.field.consume("")
+    val y: Any = Test.rawB.field.produce()
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawWithInProjection.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawWithInProjection.fir.kt
new file mode 100644
index 00000000000..db44de8b200
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/rawWithInProjection.fir.kt
@@ -0,0 +1,11 @@
+// FILE: Test.java
+
+class Test {
+    static void foo(Comparable x) {}
+}
+
+// FILE: main.kt
+
+fun main() {
+    Test.foo(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/recursiveBound.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/recursiveBound.fir.kt
new file mode 100644
index 00000000000..2c6e7839c86
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/recursiveBound.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.List;
+
+public interface A<T extends A> {}
+// FILE: main.kt
+
+class D : A<D>
+
+fun main(x: A<*>) {
+    if (x is D) {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/samRaw.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/samRaw.fir.kt
new file mode 100644
index 00000000000..761b2b25bbd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/samRaw.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.List;
+
+public interface A<T> {
+    boolean value(T t);
+}
+
+// FILE: B.java
+
+class B {
+    void foo(Runnable runnable, A x);
+
+    static A bar() {}
+}
+
+// FILE: main.kt
+
+fun main() {
+    fun println() {}
+    // All parameters in SAM adapter of `foo` have functional types
+    B().foo({ println() }, B.bar())
+    // So you should use SAM constructors when you want to use mix lambdas and Java objects
+    B().foo(Runnable { println() }, B.bar())
+    B().foo({ println() }, { it: Any? -> it == null } )
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/saveRawCapabilitiesAfterSubtitution.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/saveRawCapabilitiesAfterSubtitution.fir.kt
new file mode 100644
index 00000000000..aac713a9e7a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/saveRawCapabilitiesAfterSubtitution.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+class A<T> {
+    public class Inner<E> {
+        List<T> foo() {}
+    }
+}
+
+// FILE: Test.java
+
+class Test {
+    static A rawAField = null;
+}
+
+// FILE: main.kt
+
+val result = Test.rawAField.Inner<Double>().foo()
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/simple.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/simple.fir.kt
new file mode 100644
index 00000000000..c095717a028
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/simple.fir.kt
@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+class A<T> {
+    List<T> x;
+    Map<T, T> y;
+
+    A<Map<String, T>> z;
+
+    void foo(T x, List<T> y, List<Map<Integer, T>> z) {}
+
+    A<List<T>> bar() {}
+}
+
+// FILE: Test.java
+
+class Test {
+    static A rawAField = null;
+}
+
+// FILE: main.kt
+
+val strList: List<String> = null!!
+val strMap: Map<String, String> = null!!
+
+fun main() {
+    val rawA = Test.rawAField
+    rawA.x = strList
+    rawA.y = strMap
+    rawA.<!INAPPLICABLE_CANDIDATE!>foo<!>("", strList, strList)
+
+    val barResult = rawA.bar()
+
+    barResult.x = strList
+    barResult.y = strMap
+    barResult.<!INAPPLICABLE_CANDIDATE!>foo<!>("", strList, null)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/starProjectionToRaw.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/starProjectionToRaw.fir.kt
new file mode 100644
index 00000000000..4a89c3ce777
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/starProjectionToRaw.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+
+import java.util.*;
+
+public class A<T extends CharSequence> {}
+
+// FILE: B.java
+
+import java.util.*;
+
+public class B<E extends A> {}
+
+// FILE: Test.java
+
+class Test {
+    static void foo(B x) {}
+}
+
+// FILE: main.kt
+
+
+fun main(x: B<*>) {
+    Test.foo(x)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/rawTypes/typeEnhancement.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/typeEnhancement.fir.kt
new file mode 100644
index 00000000000..f4ebcf67d44
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/rawTypes/typeEnhancement.fir.kt
@@ -0,0 +1,27 @@
+// FILE: A.java
+
+import org.jetbrains.annotations.*;
+import java.util.*;
+
+class A<T> {
+    @NotNull
+    List<String> foo(@NotNull T x, @Nullable List<String> y) {}
+}
+
+// FILE: Test.java
+
+class Test {
+    static class DerivedRawA extends A {}
+
+    static A rawField = null;
+}
+
+// FILE: main.kt
+
+val doubleList: List<Double?> = null!!
+
+fun main() {
+    Test.rawField.<!INAPPLICABLE_CANDIDATE!>foo<!>("", doubleList)
+    Test.rawField.<!INAPPLICABLE_CANDIDATE!>foo<!>(null, doubleList)
+    Test.DerivedRawA().<!INAPPLICABLE_CANDIDATE!>foo<!>(null, doubleList)
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/safeCall.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/safeCall.fir.kt
new file mode 100644
index 00000000000..9c38f26a63d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/safeCall.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public String s() { return null; }
+}
+
+// FILE: k.kt
+import p.*
+
+fun test(j: J) {
+    j.s()?.length.checkType { _<Int?>() }
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/samAdapterInConstructor.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/samAdapterInConstructor.fir.kt
new file mode 100644
index 00000000000..d3e7f0f3441
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/samAdapterInConstructor.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_ANONYMOUS_PARAMETER
+
+// FILE: A.java
+import java.util.Comparator;
+
+public class A<E> {
+    public A(Comparator<? super E> comparator) {}
+}
+
+// FILE: main.kt
+
+fun foo() {
+    val result: A<String> = <!INAPPLICABLE_CANDIDATE!>A<!><String> { x, y -> 1 }
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/samConstructor.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/samConstructor.fir.kt
new file mode 100644
index 00000000000..51507e0d511
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/samConstructor.fir.kt
@@ -0,0 +1,17 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public static void c(java.util.Comparator<Integer> c) {}
+
+}
+
+// FILE: k.kt
+
+import java.util.*
+import p.*
+
+fun test() {
+    J.c(Comparator { a, b -> b - a })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/supertypeArgumentsExplicit.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/supertypeArgumentsExplicit.fir.kt
new file mode 100644
index 00000000000..eb566663584
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/supertypeArgumentsExplicit.fir.kt
@@ -0,0 +1,13 @@
+// !EXPLICIT_FLEXIBLE_TYPES
+
+interface A<T>
+interface B<T>: A<ft<T, T?>>
+
+interface C: A<String>, B<String>
+interface D: B<String>, A<String>
+interface E: A<String?>, B<String?>
+interface F: A<String?>, B<String>
+
+interface G: A<String>, B<String?>
+interface H: A<Int>, B<String>
+interface I: B<Int>, A<String>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.fir.kt
new file mode 100644
index 00000000000..899414d61cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.fir.kt
@@ -0,0 +1,3 @@
+// JAVAC_EXPECTED_FILE
+interface ExtMap<K, V> : Map<K, V>
+class HashMapEx<K, V> : java.util.HashMap<K, V>(), ExtMap<K, V>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/overriddenExtensions.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/overriddenExtensions.fir.kt
new file mode 100644
index 00000000000..fe29fe38d9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/overriddenExtensions.fir.kt
@@ -0,0 +1,63 @@
+// FILE: A.kt
+open class A {
+    open fun String.foo(y: String?): Int = 1
+    open fun String?.bar(y: String): Int = 1
+}
+
+class E : B1() {
+    fun baz() {
+        val x: String? = ""
+
+        x.<!INAPPLICABLE_CANDIDATE!>foo<!>(x)
+        x.<!INAPPLICABLE_CANDIDATE!>foo<!>("")
+        x.bar(x)
+        x.bar("")
+    }
+
+    override fun String.foo(y: String?): Int = 1
+    override fun String?.bar(y: String): Int = 1
+}
+
+// FILE: B.java
+import org.jetbrains.annotations.*;
+
+// Just inherit enhanced types
+class B extends A {
+    @Override
+    int foo(String x, String y);
+    @Override
+    int bar(String x, String y);
+}
+
+// FILE: B1.java
+import org.jetbrains.annotations.*;
+
+// Just inherit enhanced types (annotations without conflicts)
+public class B1 extends A {
+    @Override
+    public int foo(@NotNull String x, String y);
+    @Override
+    public int bar(@Nullable String x, String y);
+}
+
+// FILE: C.java
+import org.jetbrains.annotations.*;
+
+// Conflicting annotations. Everything is flexible
+class C extends A {
+    @Override
+    int foo(@Nullable String x, @NotNull String y);
+    @Override
+    int bar(@NotNull String x, @Nullable String y);
+}
+
+// FILE: D.java
+import org.jetbrains.annotations.*;
+
+// Just inherit enhanced types (annotations without conflicts)
+class D extends B {
+    @Override
+    int foo(@Nullable String x, @Nullable String y);
+    @Override
+    int bar(@NotNull String x, @NotNull String y);
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/saveAnnotationAfterSubstitution.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/saveAnnotationAfterSubstitution.fir.kt
new file mode 100644
index 00000000000..96c0111f5e5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/saveAnnotationAfterSubstitution.fir.kt
@@ -0,0 +1,43 @@
+// FILE: A.java
+
+import org.jetbrains.annotations.*;
+
+public interface A<T> {
+    void foo(@NotNull T x, @Nullable T y);
+}
+
+// FILE: B1.java
+
+// contains fake_override fun foo(/*0*/ org.jetbrains.annotations.NotNull() x: kotlin.String, /*1*/ org.jetbrains.annotations.Nullable() y: kotlin.String?)
+public interface B1 extends A<String> {}
+
+// FILE: B2.java
+import org.jetbrains.annotations.*;
+
+public interface B2 extends A<String> {
+    // Ok, consistent override
+    // override fun foo(/*0*/ org.jetbrains.annotations.NotNull() x: kotlin.String, /*1*/ org.jetbrains.annotations.Nullable() y: kotlin.String?)
+    void foo(@NotNull String x, @Nullable String y);
+}
+
+// FILE: B3.java
+import org.jetbrains.annotations.*;
+
+public interface B3 extends A<String> {
+    // inconsistent override, both parameters are platform
+    // override /*1*/ fun foo(/*0*/ org.jetbrains.annotations.Nullable() x: kotlin.String!, /*1*/ org.jetbrains.annotations.NotNull() y: kotlin.String!): kotlin.Unit
+    void foo(@Nullable String x, @NotNull String y);
+}
+
+// FILE: main.kt
+
+// fake_override fun foo(/*0*/ org.jetbrains.annotations.NotNull() x: kotlin.String, /*1*/ org.jetbrains.annotations.Nullable() y: kotlin.String?): kotlin.Unit
+interface C1 : A<String>
+
+// fake_override fun foo(/*0*/ org.jetbrains.annotations.NotNull() x: kotlin.String?, /*1*/ org.jetbrains.annotations.Nullable() y: kotlin.String?): kotlin.Unit
+interface C2 : A<String?>
+
+interface C3 : B1 {
+    // inconsistent override
+    override fun foo(x: String?, y: String?);
+}
diff --git a/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/supertypeDifferentParameterNullability.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/supertypeDifferentParameterNullability.fir.kt
new file mode 100644
index 00000000000..d7cb1f069f0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/supertypeDifferentParameterNullability.fir.kt
@@ -0,0 +1,33 @@
+// FILE: A.java
+import org.jetbrains.annotations.*;
+
+public interface A {
+    void foo(@Nullable String x);
+}
+
+// FILE: B.java
+import org.jetbrains.annotations.*;
+
+public interface B {
+    void foo(@NotNull String x);
+}
+
+// FILE: C.kt
+
+class C1 : A, B {
+    override fun foo(x: String) {}
+}
+
+class C2 : A, B {
+    override fun foo(x: String?) {}
+}
+
+interface I : A, B
+
+class C3 : I {
+    override fun foo(x: String) {}
+}
+
+class C4 : I {
+    override fun foo(x: String?) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/supertypeDifferentReturnNullability.fir.kt b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/supertypeDifferentReturnNullability.fir.kt
new file mode 100644
index 00000000000..ab727c004be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/platformTypes/typeEnhancement/supertypeDifferentReturnNullability.fir.kt
@@ -0,0 +1,35 @@
+// FILE: A.java
+import org.jetbrains.annotations.*;
+
+public interface A {
+    @Nullable
+    String foo();
+}
+
+// FILE: B.java
+import org.jetbrains.annotations.*;
+
+public interface B {
+    @NotNull
+    String foo();
+}
+
+// FILE: C.kt
+
+class C1 : A, B {
+    override fun foo(): String? = ""
+}
+
+class C2 : A, B {
+    override fun foo(): String = ""
+}
+
+interface I : A, B
+
+class C3 : I {
+    override fun foo(): String? = ""
+}
+
+class C4 : I {
+    override fun foo(): String = ""
+}
diff --git a/compiler/testData/diagnostics/tests/privateInFile/kt12429.fir.kt b/compiler/testData/diagnostics/tests/privateInFile/kt12429.fir.kt
new file mode 100644
index 00000000000..9cc707d89e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/privateInFile/kt12429.fir.kt
@@ -0,0 +1,4 @@
+private const val a = ""
+
+@Deprecated("$a")
+fun test() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/privateInFile/topLevelAnnotationCall.fir.kt b/compiler/testData/diagnostics/tests/privateInFile/topLevelAnnotationCall.fir.kt
new file mode 100644
index 00000000000..f3e97cd8266
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/privateInFile/topLevelAnnotationCall.fir.kt
@@ -0,0 +1,27 @@
+// FILE: 1.kt
+package pp
+
+private annotation class A(val s: String)
+private const val foo = "O"
+
+@A(foo)
+fun f1() {}
+
+@A(foo)
+val p1 = ""
+
+@A(foo)
+class C1
+
+
+// FILE: 2.kt
+package pp
+
+@A(<!INAPPLICABLE_CANDIDATE!>foo<!>)
+fun f2() {}
+
+@A(<!INAPPLICABLE_CANDIDATE!>foo<!>)
+val p2 = ""
+
+@A(<!INAPPLICABLE_CANDIDATE!>foo<!>)
+class C2
diff --git a/compiler/testData/diagnostics/tests/privateInFile/visibility.fir.kt b/compiler/testData/diagnostics/tests/privateInFile/visibility.fir.kt
new file mode 100644
index 00000000000..fdb9710d13b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/privateInFile/visibility.fir.kt
@@ -0,0 +1,54 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+//FILE:file1.kt
+package a
+
+private open class A {
+    fun bar() {}
+}
+
+private var x: Int = 10
+
+var xx: Int = 20
+  private set(value: Int) {}
+
+private fun foo() {}
+
+private fun bar() {
+    val y = x
+    x = 20
+    xx = 30
+}
+
+fun makeA() = A()
+
+private object PO {}
+
+//FILE:file2.kt
+package a
+
+fun test() {
+    val y = makeA()
+    y.bar()
+    <!INAPPLICABLE_CANDIDATE!>foo<!>()
+
+    val u : A = <!INAPPLICABLE_CANDIDATE!>A<!>()
+
+    val z = <!INAPPLICABLE_CANDIDATE!>x<!>
+    <!INAPPLICABLE_CANDIDATE!>x<!> = 30
+
+    val po = <!INAPPLICABLE_CANDIDATE!>PO<!>
+
+    val v = xx
+    xx = 40
+}
+
+class B : <!INAPPLICABLE_CANDIDATE!>A<!>() {}
+
+class Q {
+    class W {
+        fun foo() {
+            val y = makeA() //assure that 'makeA' is visible
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/properDefaultInitializationInTailrec.fir.kt b/compiler/testData/diagnostics/tests/properDefaultInitializationInTailrec.fir.kt
new file mode 100644
index 00000000000..62acd1f9aba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properDefaultInitializationInTailrec.fir.kt
@@ -0,0 +1,39 @@
+//!LANGUAGE: +ProperComputationOrderOfTailrecDefaultParameters
+import kotlin.reflect.KClass
+
+fun withEffects(): String = "OK"
+
+const val Z = "123"
+
+enum class EnumA {
+    A
+}
+
+tailrec fun foo(i: Int = 1, c: Char = '2', s: String = "1234", b: Boolean = true, d: Double = 1.0,  l: Long =  1L,  y: String = withEffects()) {
+    foo(i, c, s, b, d, l, y)
+}
+
+
+tailrec fun foo2(x: Int = 1, y: String = withEffects(), z: String = Z) {
+    foo2(x, y, z)
+}
+
+tailrec fun foo3(y: String = withEffects()) {
+    foo3(y)
+}
+
+tailrec fun foo4(x: String = withEffects(), y: String = withEffects()) {
+    foo4(x, y)
+}
+
+tailrec fun foo5(x: String = withEffects(), y: String = withEffects(), z: String = withEffects()) {
+    foo5(x, y, z)
+}
+
+tailrec fun foo6(x: String = withEffects(), y: EnumA = EnumA.A) {
+    foo6(x, y)
+}
+
+tailrec fun foo7(x: String = withEffects(), y: KClass<out EnumA> = EnumA.A::class) {
+    foo7(x, y)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.fir.kt b/compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.fir.kt
new file mode 100644
index 00000000000..5dc414355bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.fir.kt
@@ -0,0 +1,25 @@
+val String.test1: Int
+var String.test2: Int
+
+var String.test3: Int; public set
+
+class C {
+    val String.test1: Int
+    var String.test2: Int
+    var String.test3: Int; public set
+}
+
+interface I {
+    val String.test1: Int
+    var String.test2: Int
+    var String.test3: Int; public set
+}
+
+abstract class A {
+    val String.test1: Int
+    var String.test2: Int
+    var String.test3: Int; public set
+
+    abstract val String.testA1: Int
+    abstract var String.testA2: Int
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/blockBodyGetter.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/blockBodyGetter.fir.kt
new file mode 100644
index 00000000000..45062a5af6c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/blockBodyGetter.fir.kt
@@ -0,0 +1,3 @@
+val x get() {
+    return 1
+}
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/cantBeInferred.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/cantBeInferred.fir.kt
new file mode 100644
index 00000000000..8091a2cabdf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/cantBeInferred.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+val x get() = foo()
+val y get() = bar()
+
+fun <E> foo(): E = null!!
+fun <E> bar(): List<E> = null!!
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/explicitGetterType.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/explicitGetterType.fir.kt
new file mode 100644
index 00000000000..2e8bcf7bad6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/explicitGetterType.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+val x get(): String = foo()
+val y get(): List<Int> = bar()
+val z get(): List<Int> {
+    return bar()
+}
+
+val u get(): String = field
+
+fun <E> foo(): E = null!!
+fun <E> bar(): List<E> = null!!
+
+
+fun baz() {
+    x checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><List<Int>>() }
+    z checkType { <!UNRESOLVED_REFERENCE!>_<!><List<Int>>() }
+}
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/members.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/members.fir.kt
new file mode 100644
index 00000000000..59e36b0d91f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/members.fir.kt
@@ -0,0 +1,24 @@
+// !CHECK_TYPE
+class A {
+    val x get() = 1
+    val y get() = id(1)
+    val y2 get() = id(id(2))
+    val z get() = l("")
+    val z2 get() = l(id(l("")))
+
+    val <T> T.u get() = id(this)
+}
+fun <E> id(x: E) = x
+fun <E> l(x: E): List<E> = null!!
+
+fun foo(a: A) {
+    a.x checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.y checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.y2 checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.z checkType { <!UNRESOLVED_REFERENCE!>_<!><List<String>>() }
+    a.z2 checkType { <!UNRESOLVED_REFERENCE!>_<!><List<List<String>>>() }
+
+    with(a) {
+        1.u checkType { _<Int>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/nullAsNothing.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/nullAsNothing.fir.kt
new file mode 100644
index 00000000000..0ac6589f0c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/nullAsNothing.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+val x get() = null
+val y get() = null!!
+
+fun foo() {
+    x checkType { <!UNRESOLVED_REFERENCE!>_<!><Nothing?>() }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><Nothing>() }
+}
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/objectExpression.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/objectExpression.fir.kt
new file mode 100644
index 00000000000..9be9503435e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/objectExpression.fir.kt
@@ -0,0 +1,36 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+object Outer {
+    private var x
+        get() = object : CharSequence {
+            override val length: Int
+                get() = 0
+
+            override fun get(index: Int): Char {
+                <!UNRESOLVED_REFERENCE!>checkSubtype<!><CharSequence>(x)
+                return ' '
+            }
+
+            override fun subSequence(startIndex: Int, endIndex: Int) = ""
+
+            fun bar() {
+            }
+        }
+        set(q) {
+            <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><CharSequence>(x)
+            y = q
+            x = q
+        }
+
+    private var y = x
+
+    fun foo() {
+        x = y
+
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><CharSequence>(x)
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><CharSequence>(y)
+
+        x.<!UNRESOLVED_REFERENCE!>bar<!>()
+        y.<!UNRESOLVED_REFERENCE!>bar<!>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/overrides.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/overrides.fir.kt
new file mode 100644
index 00000000000..c329821e32d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/overrides.fir.kt
@@ -0,0 +1,41 @@
+// !CHECK_TYPE
+interface A {
+    val x: Int
+
+    val z: Comparable<*>
+}
+
+open class B {
+    open var y = ""
+
+    open val z: CharSequence = ""
+}
+
+class C : B(), A {
+    override val x
+        get() = 1
+
+    override var y
+        get() = super.y
+        set(value) {
+            value checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+        }
+
+    override var z
+        get() = ""
+        set(value) {
+            value checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+        }
+}
+
+fun foo(c: C) {
+    c.x checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    c.y checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    c.z checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    c.y = ""
+    c.y = 1
+
+    c.z = ""
+    c.z = 1
+}
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/primaryConstructorParameter.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/primaryConstructorParameter.fir.kt
new file mode 100644
index 00000000000..9eb73a466d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/primaryConstructorParameter.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Delegate {
+    operator fun getValue(x: Any?, y: Any?): String = ""
+}
+
+fun <T> delegateFactory(p: Any) = Delegate
+
+class C(p: Any, val v: Any) {
+
+    val test1 get() = p
+
+    val test2 get() = v
+
+    // NB here we can use both 'T' (property type parameter) and 'p' (primary constructor parameter)
+    val <T> List<T>.test3 by delegateFactory<T>(p)
+
+    val test4 get() { return p }
+
+    var test5
+        get() { return p }
+        set(nv) { p.let {} }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/recursiveGetter.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/recursiveGetter.fir.kt
new file mode 100644
index 00000000000..7550d94921b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/recursiveGetter.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// NI_EXPECTED_FILE
+
+val x get() = x
+
+class A {
+    val y get() = y
+
+    val a get() = b
+    val b get() = a
+
+    val z1 get() = <!UNRESOLVED_REFERENCE!>id<!>(z1)
+    val z2 get() = <!UNRESOLVED_REFERENCE!>l<!>(z2)
+
+    val u get() = field
+}
+
+fun <E> id(x: E) = x
+fun <E> l(x: E): List<E> = null!!
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/topLevel.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/topLevel.fir.kt
new file mode 100644
index 00000000000..fee3f677993
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/topLevel.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+val x get() = 1
+val y get() = id(1)
+val y2 get() = id(id(2))
+val z get() = l("")
+val z2 get() = l(id(l("")))
+
+val <T> T.u get() = id(this)
+
+fun <E> id(x: E) = x
+fun <E> l(x: E): List<E> = null!!
+
+fun foo() {
+    x checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    y2 checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    z checkType { <!UNRESOLVED_REFERENCE!>_<!><List<String>>() }
+    z2 checkType { <!UNRESOLVED_REFERENCE!>_<!><List<List<String>>>() }
+
+    1.u checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/unsupportedInferenceFromGetters.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/unsupportedInferenceFromGetters.fir.kt
new file mode 100644
index 00000000000..ba0c9f422bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/unsupportedInferenceFromGetters.fir.kt
@@ -0,0 +1,71 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: -ShortSyntaxForPropertyGetters
+// NI_EXPECTED_FILE
+
+// blockBodyGetter.kt
+val x get() {
+    return 1
+}
+
+// cantBeInferred.kt
+val x1 get() = foo()
+val y1 get() = bar()
+
+fun <E> foo(): E = null!!
+fun <E> bar(): List<E> = null!!
+
+// explicitGetterType.kt
+val x2 get(): String = foo()
+val y2 get(): List<Int> = bar()
+val z2 get(): List<Int> {
+    return bar()
+}
+
+val u get(): String = field
+
+// members.kt
+class A {
+    val x get() = 1
+    val y get() = id(1)
+    val y2 get() = id(id(2))
+    val z get() = l("")
+    val z2 get() = l(id(l("")))
+
+    val <T> T.u get() = id(this)
+}
+fun <E> id(x: E) = x
+fun <E> l(x: E): List<E> = null!!
+
+// vars
+var x3
+    get() = 1
+    set(q) {
+    }
+
+// recursive
+val x4 get() = x4
+
+// null as nothing
+val x5 get() = null
+val y5 get() = null!!
+
+// objectExpression.kt
+object Outer {
+    private var x
+        get() = object : CharSequence {
+            override val length: Int
+                get() = 0
+
+            override fun get(index: Int): Char {
+                return ' '
+            }
+
+            override fun subSequence(startIndex: Int, endIndex: Int) = ""
+
+            fun bar() {
+            }
+        }
+        set(q) {
+            x = q
+        }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/vars.fir.kt b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/vars.fir.kt
new file mode 100644
index 00000000000..d8e9261d7f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/inferenceFromGetters/vars.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+var x
+    get() = 1
+    set(q) {
+        q checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    }
+
+var noSetter
+    get() = 1
+
+
+fun foo() {
+    x checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    noSetter checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    x = 1
+    x = ""
+
+    noSetter = 2
+    noSetter = ""
+}
diff --git a/compiler/testData/diagnostics/tests/properties/lateinitOnTopLevel.fir.kt b/compiler/testData/diagnostics/tests/properties/lateinitOnTopLevel.fir.kt
new file mode 100644
index 00000000000..f13d54e7923
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/properties/lateinitOnTopLevel.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +LateinitTopLevelProperties
+
+object Delegate {
+    operator fun getValue(instance: Any?, property: Any) : String = ""
+    operator fun setValue(instance: Any?, property: Any, value: String) {}
+}
+
+lateinit var testOk: String
+
+lateinit val testErr0: Any
+lateinit var testErr1: Int
+lateinit var testErr2: Any?
+lateinit var testErr3: String = ""
+lateinit var testErr4 by Delegate
diff --git a/compiler/testData/diagnostics/tests/publishedApi.fir.kt b/compiler/testData/diagnostics/tests/publishedApi.fir.kt
new file mode 100644
index 00000000000..a1d00b75dcc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/publishedApi.fir.kt
@@ -0,0 +1,71 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@kotlin.PublishedApi
+class A
+
+@kotlin.PublishedApi
+internal class B
+
+@kotlin.PublishedApi
+private class C
+
+
+@kotlin.PublishedApi
+fun a() {}
+
+@kotlin.PublishedApi
+internal fun b() {}
+
+@kotlin.PublishedApi
+internal fun c() {}
+
+
+@kotlin.PublishedApi
+var ap = 1
+
+@kotlin.PublishedApi
+internal var bp = 1
+
+@kotlin.PublishedApi
+internal var c = 1
+
+
+
+class E {
+    @kotlin.PublishedApi
+    fun a() {}
+
+    @kotlin.PublishedApi
+    internal fun b() {}
+
+    @kotlin.PublishedApi
+    private fun c() {}
+
+    @kotlin.PublishedApi
+    protected fun d() {}
+
+
+    @kotlin.PublishedApi
+    val ap = 1
+
+    @kotlin.PublishedApi
+    internal val bp = 1
+
+    @kotlin.PublishedApi
+    protected val c = 1
+
+    @kotlin.PublishedApi
+    private val d = 1
+}
+
+
+class D @kotlin.PublishedApi constructor() {
+
+    @kotlin.PublishedApi
+    constructor(a: String) : this()
+
+    @kotlin.PublishedApi
+    private constructor(a: String, b: String): this()
+
+    @kotlin.PublishedApi
+    internal constructor(a: String, b: String, c: String): this()
+}
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/GenericClassVsPackage.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/GenericClassVsPackage.fir.kt
new file mode 100644
index 00000000000..8b40039c0d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/GenericClassVsPackage.fir.kt
@@ -0,0 +1,76 @@
+// MODULE: m1
+// FILE: a.kt
+package a.b
+
+class c {
+    fun ab_c() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+package a
+
+class b<T> {
+    class c {
+        fun a_bc() {}
+    }
+}
+
+// MODULE: m3(m1, m2)
+// FILE: c.kt
+import a.b.c
+
+fun test(ab_c: c) {
+    ab_c.ab_c()
+
+    val ab_c2: a.b.c = a.b.c()
+    ab_c2.ab_c()
+
+    val ab_c3 = a.b.c()
+    ab_c3.ab_c()
+}
+
+// NB according to the maximum package prefix rule, 'a.b.c' denotes 'c' in package 'a.b' (thus ab_c, not a_bc)
+fun test2(ab_c: a.b.c) {
+    ab_c.<!UNRESOLVED_REFERENCE!>a_bc<!>()
+    ab_c.ab_c()
+}
+
+
+
+//---------------------------TOP LEVEL----------
+// MODULE: top_m1
+// FILE: top_a.kt
+package a
+
+class b {
+    fun a_b() {}
+}
+
+// MODULE: top_m2
+// FILE: top_b.kt
+class a<T> {
+    class b {
+        fun _ab() {}
+    }
+    fun _a() {}
+}
+
+// MODULE: top_m3(top_m1, top_m2)
+// FILE: top_c.kt
+import a.b
+
+fun test(a_b: b) {
+    a_b.a_b()
+
+    val _ab: a.b = a.b()
+    _ab._ab()
+
+    val _ab2 = a.b()
+    _ab2._ab()
+}
+
+fun test2(_ab: a.b) {
+    _ab._ab()
+    _ab.<!UNRESOLVED_REFERENCE!>a_b<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/JavaQualifier.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/JavaQualifier.fir.kt
new file mode 100644
index 00000000000..b0f497158d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/JavaQualifier.fir.kt
@@ -0,0 +1,9 @@
+// FILE: Owner.java
+
+public class Owner {
+    public static final String name = "Owner";
+}
+
+// FILE: Use.kt
+
+val x = Owner.name
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsClass.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsClass.fir.kt
new file mode 100644
index 00000000000..53c311808ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsClass.fir.kt
@@ -0,0 +1,88 @@
+// MODULE: m1
+// FILE: a.kt
+package a.b
+
+class c {
+    fun ab_c() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+package a
+
+fun a_fun() {}
+
+class b {
+    fun a_b() {}
+
+    class c {
+        fun a_bc() {}
+    }
+}
+
+// MODULE: m3(m1, m2)
+// FILE: c.kt
+
+fun test(a_b: a.b) {
+    a_b.a_b()
+
+    val ab_c: a.b.c = a.b.c()
+    ab_c.ab_c()
+    ab_c.<!UNRESOLVED_REFERENCE!>a_bc<!>()
+
+    val ab_c2 = a.b.c()
+    ab_c2.ab_c()
+    ab_c2.<!UNRESOLVED_REFERENCE!>a_bc<!>()
+}
+
+fun test2(ab_c: a.b.c) {
+    ab_c.ab_c()
+}
+
+//---- Changed dependence order
+// MODULE: _m1
+// FILE: _a.kt
+package a.b
+
+fun ab_fun() {}
+
+class c {
+    fun ab_c() {}
+
+    class d {
+        fun ab_cd() {}
+    }
+}
+
+// MODULE: _m2
+// FILE: _b.kt
+package a
+
+fun a_fun() {}
+
+class b {
+    fun a_b() {}
+
+    class c {
+        fun a_bc() {}
+    }
+}
+
+// MODULE: _m3(_m1, _m2)
+// FILE: _c.kt
+
+fun test(a_b: a.b) {
+    a_b.a_b()
+
+    val ab_c: a.b.c = a.b.c()
+    ab_c.ab_c()
+    ab_c.<!UNRESOLVED_REFERENCE!>a_bc<!>()
+
+    val ab_c2 = a.b.c()
+    ab_c2.ab_c()
+    ab_c2.<!UNRESOLVED_REFERENCE!>a_bc<!>()
+}
+
+fun test2(ab_c: a.b.c) {
+    ab_c.ab_c()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsClass2.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsClass2.fir.kt
new file mode 100644
index 00000000000..6cccc7a53f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsClass2.fir.kt
@@ -0,0 +1,33 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// MODULE: m1
+// FILE: a.kt
+package a
+
+class a {
+    companion object {}
+}
+
+class b {
+    fun a_b() {}
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package test
+
+class a
+
+val x = a.<!UNRESOLVED_REFERENCE!>b<!>()
+
+// MODULE: m3(m1)
+// FILE: c.kt
+package test
+
+import a.a
+
+fun foo(i: a) {
+    a
+    a()
+    a.<!UNRESOLVED_REFERENCE!>a<!>
+    a.<!UNRESOLVED_REFERENCE!>a<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsRootClass.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsRootClass.fir.kt
new file mode 100644
index 00000000000..e81b8ef51d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsRootClass.fir.kt
@@ -0,0 +1,44 @@
+// MODULE: m1
+// FILE: a.kt
+package a
+
+class b {
+    fun a_b() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+class a {
+    class b {
+        fun _ab() {}
+    }
+}
+
+// MODULE: m3(m1, m2)
+// FILE: c1.kt
+package some
+
+fun test(a_b: a.b) {
+    a_b.a_b()
+
+    val a_b2 = a.b()
+    a_b2.a_b()
+}
+
+// FILE: c2.kt
+package a
+
+fun test(a_b: a.b) {
+    a_b.a_b()
+
+    val a_b2 = a.b()
+    a_b2.a_b()
+}
+
+// FILE: c3.kt
+fun test(_ab: a.b) {
+    _ab._ab()
+
+    val _ab2 = a.b()
+    _ab2._ab() // todo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/TypeWithError.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/TypeWithError.fir.kt
new file mode 100644
index 00000000000..852b5d5c946
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/TypeWithError.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE -UNREACHABLE_CODE
+// !WITH_NEW_INFERENCE
+
+class A {
+    class B {
+        class C
+    }
+}
+
+fun test(a: A.<!SYNTAX!><!>): A.<!SYNTAX!><!> {
+    val aa: A. <!SYNTAX!>=<!><!SYNTAX!><!> null!!
+}
+
+fun test1(a: A.B.<!SYNTAX!><!>): A.B.<!SYNTAX!><!> {
+    val aa: A.B. <!SYNTAX!>=<!><!SYNTAX!><!> null!!
+}
+
+fun test2(a: A.e.C): A.e.C {
+    val aa: A.e.C = null!!
+}
+
+fun test3(a: a.A.C): a.A.C {
+    val aa: a.A.C = null!!
+}
+
+fun test4(a: A.B.ee): A.B.ee {
+    val aa: A.B.ee = null!!
+}
+
+fun test5(a: A.ee): A.ee {
+    val aa: A.ee = null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/calleeExpressionAsCallExpression.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/calleeExpressionAsCallExpression.fir.kt
new file mode 100644
index 00000000000..5f2399d1564
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/calleeExpressionAsCallExpression.fir.kt
@@ -0,0 +1,2 @@
+// !WITH_NEW_INFERENCE
+val unwrapped = <!UNRESOLVED_REFERENCE!>some<!><<!UNRESOLVED_REFERENCE!><!UNRESOLVED_REFERENCE!><!UNRESOLVED_REFERENCE!>sdf<!>()()<!><out Any><!>::unwrap
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/nullCalleeExpression.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/nullCalleeExpression.fir.kt
new file mode 100644
index 00000000000..81fced65a49
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/nullCalleeExpression.fir.kt
@@ -0,0 +1,4 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+val unwrapped = some.<!SYNTAX!><<!><!UNRESOLVED_REFERENCE!>cabc<!><!SYNTAX!>$Wrapper<!><out Any>::unwrap
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/qualifiedExpression/visibleClassVsQualifiedClass.fir.kt b/compiler/testData/diagnostics/tests/qualifiedExpression/visibleClassVsQualifiedClass.fir.kt
new file mode 100644
index 00000000000..9e9cebd91d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/qualifiedExpression/visibleClassVsQualifiedClass.fir.kt
@@ -0,0 +1,58 @@
+// MODULE: m1
+// FILE: a.kt
+package a
+
+class b {
+    fun a_b() {}
+}
+
+// MODULE: m2
+// FILE: b.kt
+package some
+
+class a {
+    class b {
+        fun some_ab() {}
+    }
+}
+
+// MODULE: m3(m1, m2)
+// FILE: c1.kt
+package other
+
+class a {}
+
+fun test(a_: a.b) {
+    a_.a_b()
+
+    val a_2 = a.<!UNRESOLVED_REFERENCE!>b<!>()
+    a_2.<!UNRESOLVED_REFERENCE!>a_b<!>()
+    a_2.<!UNRESOLVED_REFERENCE!>some_ab<!>()
+    a_2.<!UNRESOLVED_REFERENCE!>a_<!>()
+}
+
+// FILE: c2.kt
+package other2
+
+class a {
+    class b {
+        fun other2_ab() {}
+    }
+}
+
+fun test(_ab: a.b) {
+    _ab.other2_ab()
+
+    val _ab2 = a.b()
+    _ab2.other2_ab()
+}
+
+// FILE: c3.kt
+package some
+
+fun test(_ab: a.b) {
+    _ab.some_ab()
+
+    val _ab2 = a.b()
+    _ab2.some_ab()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/afterfor.fir.kt b/compiler/testData/diagnostics/tests/reassignment/afterfor.fir.kt
new file mode 100644
index 00000000000..17d208686ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/afterfor.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(k: Int): Int {
+    val i: Int
+    for (j in 1..k) {
+        i = j
+    }
+    i = 6
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/dowhile.fir.kt b/compiler/testData/diagnostics/tests/reassignment/dowhile.fir.kt
new file mode 100644
index 00000000000..8d76e571678
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/dowhile.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(): Int {
+    val i: Int
+    var j = 0
+    do {
+        i = ++j
+    } while (j < 5)
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/else.fir.kt b/compiler/testData/diagnostics/tests/reassignment/else.fir.kt
new file mode 100644
index 00000000000..3b3d5f2f6d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/else.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(f: Boolean): Int {
+    val i: Int
+    if (f) {}
+    else {
+        i = 2
+    }
+    i = 3
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/foronly.fir.kt b/compiler/testData/diagnostics/tests/reassignment/foronly.fir.kt
new file mode 100644
index 00000000000..bc5907df2c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/foronly.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(k: Int): Int {
+    val i: Int
+    for (j in 1..k) {
+        i = j
+    }
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/if.fir.kt b/compiler/testData/diagnostics/tests/reassignment/if.fir.kt
new file mode 100644
index 00000000000..3b69ff4fb28
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/if.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(f: Boolean): Int {
+    val i: Int
+    if (f) {
+        i = 1
+    }
+    i = 3
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/ifelse.fir.kt b/compiler/testData/diagnostics/tests/reassignment/ifelse.fir.kt
new file mode 100644
index 00000000000..4a7acfd06f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/ifelse.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(f: Boolean): Int {
+    val i: Int
+    if (f) {
+        i = 1
+    }
+    else {
+        i = 2
+    }
+    i = 3
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/noifelse.fir.kt b/compiler/testData/diagnostics/tests/reassignment/noifelse.fir.kt
new file mode 100644
index 00000000000..b096df5bcdb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/noifelse.fir.kt
@@ -0,0 +1,6 @@
+fun foo(f: Boolean): Int {
+    val i: Int
+    if (f) {}
+    i = 3
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/when.fir.kt b/compiler/testData/diagnostics/tests/reassignment/when.fir.kt
new file mode 100644
index 00000000000..bdc46e59d62
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/when.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(f: Boolean): Int {
+    val i: Int
+    when (f) {
+        true -> i = 1
+    }
+    i = 3
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/reassignment/whiletrue.fir.kt b/compiler/testData/diagnostics/tests/reassignment/whiletrue.fir.kt
new file mode 100644
index 00000000000..a17eabfa441
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reassignment/whiletrue.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VALUE
+
+fun foo(): Int {
+    val i: Int
+    var j = 0
+    while (true) {
+        i = ++j
+        if (j > 5) break
+    } 
+    return i
+}
diff --git a/compiler/testData/diagnostics/tests/recovery/absentLeftHandSide.fir.kt b/compiler/testData/diagnostics/tests/recovery/absentLeftHandSide.fir.kt
new file mode 100644
index 00000000000..2a108a6ca91
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/recovery/absentLeftHandSide.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+fun import() {
+    <!UNRESOLVED_REFERENCE!>import<!> <!UNRESOLVED_REFERENCE!>a<!><!SYNTAX!>.<!><!UNRESOLVED_REFERENCE!>*<!><!SYNTAX!><!>
+}
+
+fun composite() {
+    val s = 13<!AMBIGUITY!>+<!><!SYNTAX!>~<!><!UNRESOLVED_REFERENCE!>/<!>12
+}
+
+fun html() {
+    <!SYNTAX!><<!><!UNRESOLVED_REFERENCE!>html<!>><!SYNTAX!><<!><!UNRESOLVED_REFERENCE!>/<!><!UNRESOLVED_REFERENCE!>html<!>><!SYNTAX!><!>
+}
+
+fun html1() {
+    <!SYNTAX!><<!><!UNRESOLVED_REFERENCE!>html<!>><!SYNTAX!><<!><!UNRESOLVED_REFERENCE!>/<!><!UNRESOLVED_REFERENCE!>html<!>><!UNRESOLVED_REFERENCE!>html<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/recovery/emptyTypeArgs.fir.kt b/compiler/testData/diagnostics/tests/recovery/emptyTypeArgs.fir.kt
new file mode 100644
index 00000000000..4152b60aa97
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/recovery/emptyTypeArgs.fir.kt
@@ -0,0 +1,3 @@
+fun main(args: Array<String>) {
+    args is Array<<!SYNTAX!><!>>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/recovery/namelessInJava.fir.kt b/compiler/testData/diagnostics/tests/recovery/namelessInJava.fir.kt
new file mode 100644
index 00000000000..78d2e8f4415
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/recovery/namelessInJava.fir.kt
@@ -0,0 +1,18 @@
+// JAVAC_SKIP
+// FILE: p/Nameless.java
+
+package p;
+
+public class Nameless {
+    void () {}
+    int ;
+}
+
+// FILE: k.kt
+
+import p.*
+
+class K : Nameless() {
+    fun () {}
+    val<!SYNTAX!><!> : Int = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/recovery/namelessMembers.fir.kt b/compiler/testData/diagnostics/tests/recovery/namelessMembers.fir.kt
new file mode 100644
index 00000000000..6bd0aa7f1fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/recovery/namelessMembers.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -REDECLARATION -DUPLICATE_CLASS_NAMES
+
+class C {
+    fun () {
+
+    }
+
+    val<!SYNTAX!><!> : Int = 1
+
+    class<!SYNTAX!><!> {}
+
+    enum class<!SYNTAX!><!> {}
+}
+
+class C1<<!SYNTAX!>in<!>> {}
+
+class C2(val<!SYNTAX!><!>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/recovery/namelessToplevelDeclarations.fir.kt b/compiler/testData/diagnostics/tests/recovery/namelessToplevelDeclarations.fir.kt
new file mode 100644
index 00000000000..4c13a3703b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/recovery/namelessToplevelDeclarations.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -REDECLARATION
+
+package<!SYNTAX!><!>
+
+fun () {
+
+}
+
+val<!SYNTAX!><!> : Int = 1
+
+
+class<!SYNTAX!><!> {
+
+}
+
+interface<!SYNTAX!><!> {
+
+}
+
+object<!SYNTAX!><!> {
+
+}
+
+enum class<!SYNTAX!><!> {}
+
+annotation class<!SYNTAX!><!> {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/ClassRedeclarationInDifferentFiles.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/ClassRedeclarationInDifferentFiles.fir.kt
new file mode 100644
index 00000000000..c6b6cfd77f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/ClassRedeclarationInDifferentFiles.fir.kt
@@ -0,0 +1,11 @@
+// FILE: f1.kt
+package test
+
+class A
+class F1
+
+// FILE: f2.kt
+package test
+
+class A
+class F2
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/ConflictingExtensionProperties.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/ConflictingExtensionProperties.fir.kt
new file mode 100644
index 00000000000..4a0c17cc96f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/ConflictingExtensionProperties.fir.kt
@@ -0,0 +1,4 @@
+package foo
+
+val Int.foo: Int get() = 2
+val Int.foo: Int get() = 3
diff --git a/compiler/testData/diagnostics/tests/redeclarations/DuplicateParameterNamesInFunctionType.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/DuplicateParameterNamesInFunctionType.fir.kt
new file mode 100644
index 00000000000..5d6770c5b77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/DuplicateParameterNamesInFunctionType.fir.kt
@@ -0,0 +1,7 @@
+fun test0(f: (String, String) -> Unit) {
+    f("", "")
+}
+
+fun test1(f: (a: Int, a: Int) -> Unit) {
+    f(1, 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/EnumName.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/EnumName.fir.kt
new file mode 100644
index 00000000000..9aa96f3064e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/EnumName.fir.kt
@@ -0,0 +1,3 @@
+enum class A {
+    name
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/FunVsCtorInDifferentFiles.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/FunVsCtorInDifferentFiles.fir.kt
new file mode 100644
index 00000000000..0e47fe33efd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/FunVsCtorInDifferentFiles.fir.kt
@@ -0,0 +1,10 @@
+// FILE: test1.kt
+class A
+class B(val x: Int) {
+    constructor(x: Int, y: Int): this(x + y)
+}
+
+// FILE: test2.kt
+fun A() {}
+fun B(x: Int) = x
+fun B(x: Int, y: Int) = x + y
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/MultiFilePackageRedeclaration.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/MultiFilePackageRedeclaration.fir.kt
new file mode 100644
index 00000000000..878e410c051
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/MultiFilePackageRedeclaration.fir.kt
@@ -0,0 +1,7 @@
+// FILE: f.kt
+package a
+class b {}
+// FILE: f.kt
+package a.b
+// FILE: f.kt
+package a.b
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/NoRedeclarationForClassesInDefaultObject.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/NoRedeclarationForClassesInDefaultObject.fir.kt
new file mode 100644
index 00000000000..4ccc2f901a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/NoRedeclarationForClassesInDefaultObject.fir.kt
@@ -0,0 +1,12 @@
+package kt2247
+
+class B {
+    companion object {
+        class Y {
+        }
+    }
+
+    class Y {
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/NoRedeclarationForEnumEntriesAndDefaultObjectMembers.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/NoRedeclarationForEnumEntriesAndDefaultObjectMembers.fir.kt
new file mode 100644
index 00000000000..cc2979f1768
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/NoRedeclarationForEnumEntriesAndDefaultObjectMembers.fir.kt
@@ -0,0 +1,11 @@
+enum class E {
+    FIRST,
+
+    SECOND;
+
+    companion object {
+        class FIRST
+
+        val SECOND = this
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/PropertyAndFunInClass.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/PropertyAndFunInClass.fir.kt
new file mode 100644
index 00000000000..651d4ac0235
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/PropertyAndFunInClass.fir.kt
@@ -0,0 +1,9 @@
+class A() {
+    val a: Int = 1
+    fun a(): Int = 2
+}
+
+class B() {
+    fun b(): Int = 2
+    val b: Int = 1
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/PropertyAndInnerClass.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/PropertyAndInnerClass.fir.kt
new file mode 100644
index 00000000000..897272f303d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/PropertyAndInnerClass.fir.kt
@@ -0,0 +1,13 @@
+public class A() {
+    public val FOO: String = "test"
+
+    public class FOO() { }
+}
+
+public class B() {
+   companion object {
+      public val FOO: String = "test"
+      
+      public class FOO() { }
+   }
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationInDefaultObject.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationInDefaultObject.fir.kt
new file mode 100644
index 00000000000..dbacb0355db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationInDefaultObject.fir.kt
@@ -0,0 +1,6 @@
+class A {
+    companion object B {
+        class G
+        val G = 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationInMultiFile.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationInMultiFile.fir.kt
new file mode 100644
index 00000000000..2e34762bb74
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationInMultiFile.fir.kt
@@ -0,0 +1,9 @@
+// FILE: a.kt
+val a : Int = 1
+fun f() {
+}
+
+// FILE: b.kt
+val a : Int = 1
+fun f() {
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationMainInFile.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationMainInFile.fir.kt
new file mode 100644
index 00000000000..c6a009b2b61
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationMainInFile.fir.kt
@@ -0,0 +1,4 @@
+// KT-9733 No error shown for 2 "main" functions in the same file
+
+fun main(args: Array<String>) {}
+fun main(args: Array<String>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationMainInMultiFile.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationMainInMultiFile.fir.kt
new file mode 100644
index 00000000000..b98f96fdc4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationMainInMultiFile.fir.kt
@@ -0,0 +1,5 @@
+// FILE: a.kt
+fun main() {}
+
+// FILE: b.kt
+fun main() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain.fir.kt
new file mode 100644
index 00000000000..41583bce9c6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain.fir.kt
@@ -0,0 +1,5 @@
+// FILE: a.kt
+fun main() {}
+
+// FILE: b.kt
+fun main() {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMainInvalid.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMainInvalid.fir.kt
new file mode 100644
index 00000000000..be65bf3c15c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMainInvalid.fir.kt
@@ -0,0 +1,7 @@
+// FILE: a.kt
+fun main() {}
+
+suspend fun main(args: Array<String>) {}
+
+// FILE: b.kt
+fun main() {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain_before.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain_before.fir.kt
new file mode 100644
index 00000000000..28f0c97317c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationParameterlessMain_before.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: -ExtendedMainConvention
+
+// FILE: a.kt
+fun main() {}
+
+// FILE: b.kt
+fun main() {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile.fir.kt
new file mode 100644
index 00000000000..edb92ec06bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile.fir.kt
@@ -0,0 +1,5 @@
+// FILE: a.kt
+suspend fun main() {}
+
+// FILE: b.kt
+suspend fun main() {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile_before.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile_before.fir.kt
new file mode 100644
index 00000000000..53601588209
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationSuspendMainInMultiFile_before.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: -ExtendedMainConvention
+
+// FILE: a.kt
+suspend fun main(args: Array<String>) {}
+
+// FILE: b.kt
+suspend fun main(args: Array<String>) {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/Redeclarations.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/Redeclarations.fir.kt
new file mode 100644
index 00000000000..f73cefbdb20
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/Redeclarations.fir.kt
@@ -0,0 +1,15 @@
+// FILE: f.kt
+package redeclarations
+  object A {
+    val x : Int = 0
+
+    val A = 1
+  }
+
+  class A {}
+
+  val A = 1
+
+// FILE: f.kt
+  package redeclarations.A
+    class A {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclarationsInObjects.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationsInObjects.fir.kt
new file mode 100644
index 00000000000..69d28fec063
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclarationsInObjects.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -DUPLICATE_CLASS_NAMES
+// KT-3525
+object B {
+    class C
+    class C
+
+    val a : Int = 1
+    val a : Int = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclaredTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclaredTypeParameters.fir.kt
new file mode 100644
index 00000000000..ed1cc72fc2a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclaredTypeParameters.fir.kt
@@ -0,0 +1,6 @@
+fun <T, T> Pair() {}
+
+class P<T, T> {}
+
+val <T, T> T.foo : Int
+    get() = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/RedeclaringPrivateToFile.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/RedeclaringPrivateToFile.fir.kt
new file mode 100644
index 00000000000..048c5bf2a5c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/RedeclaringPrivateToFile.fir.kt
@@ -0,0 +1,49 @@
+// FILE: a.kt
+package a
+
+interface A
+interface B : A
+
+private fun validFun() {}
+private val validVal = 1
+
+private fun invalidFun0() {}
+private val invalidProp0 = 1
+
+// NB invalidFun0 and invalidProp0 are conflicting overloads, since the following is an ambiguity:
+fun useInvalidFun0() = invalidFun0()
+fun useInvalidProp0() = invalidProp0
+
+private fun invalidFun1() {}
+private fun invalidFun1() {}
+
+private fun invalidFun2() {}
+public fun invalidFun2() {}
+
+public fun invalidFun3() {}
+
+private fun invalidFun4() {}
+public fun invalidFun4() {}
+
+public fun validFun2(a: A) = a
+public fun validFun2(b: B) = b
+
+// FILE: b.kt
+package a
+
+private fun validFun() {}
+private val validVal = 1
+
+private fun invalidFun0() {}
+
+private val invalidProp0 = 1
+
+internal fun invalidFun3() {}
+internal fun invalidFun4() {}
+
+// FILE: c.kt
+package a
+
+public fun invalidFun0() {}
+
+public val invalidProp0 = 1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/SingletonAndFunctionSameName.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/SingletonAndFunctionSameName.fir.kt
new file mode 100644
index 00000000000..ee0f5f28a01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/SingletonAndFunctionSameName.fir.kt
@@ -0,0 +1,21 @@
+fun Foo() = 42
+
+object Foo {
+    fun Bar() = 239
+
+    object Bar
+}
+
+
+
+fun En() = 239
+
+enum class En {
+    ENTRY,
+
+    SUBCLASS { };
+
+    fun ENTRY() = 42
+
+    fun SUBCLASS() = <!AMBIGUITY!>ENTRY<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/TopLevelPropertyVsClassifier.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/TopLevelPropertyVsClassifier.fir.kt
new file mode 100644
index 00000000000..d34d5646823
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/TopLevelPropertyVsClassifier.fir.kt
@@ -0,0 +1,13 @@
+val Test1 = null
+class Test1
+
+val Test2 = null
+interface Test2
+
+val Test3 = null
+object Test3
+
+val Test4 = null
+class Test4
+interface Test4
+object Test4
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/TypeAliasCtorVsFun.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/TypeAliasCtorVsFun.fir.kt
new file mode 100644
index 00000000000..7ef178e52bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/TypeAliasCtorVsFun.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+class C(val x: Int)
+
+typealias CC = C
+
+fun CC(x: Int) = x
+
+class Outer {
+    class C(val x: Int)
+
+    typealias CC = C
+
+    fun CC(x: Int) = x
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/TypeAliasVsClass.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/TypeAliasVsClass.fir.kt
new file mode 100644
index 00000000000..6865692e7d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/TypeAliasVsClass.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+// FILE: file1.kt
+class SomeClass
+
+typealias SomeClass = Any
+typealias SomeClass = Any
+typealias SomeClass = Any
+
+class Outer {
+    class Nested
+
+    typealias Nested = Any
+    typealias Nested = Any
+    typealias Nested = Any
+}
+
+// FILE: file2.kt
+typealias SomeClass = Any
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/TypeAliasVsProperty.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/TypeAliasVsProperty.fir.kt
new file mode 100644
index 00000000000..a52cf540780
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/TypeAliasVsProperty.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+// FILE: file1.kt
+typealias Test = String
+
+val Test = 42
+
+class Outer {
+    typealias Test = String
+
+    val Test = 42
+}
+
+typealias Test2 = String
+
+// FILE: file2.kt
+val Test2 = 42
diff --git a/compiler/testData/diagnostics/tests/redeclarations/interfaceTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/interfaceTypeParameters.fir.kt
new file mode 100644
index 00000000000..774f0c684ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/interfaceTypeParameters.fir.kt
@@ -0,0 +1,6 @@
+interface Test1<T, T>
+interface Test2<X, Y, X>
+
+class Outer<T> {
+    interface TestNested<T>
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/kt2418.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/kt2418.fir.kt
new file mode 100644
index 00000000000..8089c93e100
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/kt2418.fir.kt
@@ -0,0 +1,27 @@
+//KT-2418 Front-end allows enum constants with same name
+
+package kt2418
+
+enum class A {
+    FOO,
+    FOO
+}
+
+enum class B {
+    FOO;
+    
+    fun FOO() {}
+}
+
+enum class C {
+    FOO;
+    
+    val FOO = 1
+}
+
+enum class D {
+    FOO;
+    
+    class FOO {}
+}
+
diff --git a/compiler/testData/diagnostics/tests/redeclarations/kt2438.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/kt2438.fir.kt
new file mode 100644
index 00000000000..e559d20a8b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/kt2438.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -DUPLICATE_CLASS_NAMES
+//KT-2438 Prohibit inner classes with the same name
+
+package kt2438
+
+class B {
+    class C
+    class C
+}
+
+
+
+class A {
+    class B
+    
+    companion object {
+        class B
+        class B
+    }
+    
+    class B
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/kt470.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/kt470.fir.kt
new file mode 100644
index 00000000000..167ac8dbfd7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/kt470.fir.kt
@@ -0,0 +1,37 @@
+val a : Int = 1
+val a : Int = 1
+val a : Int = 1
+
+val b : Int = 1
+val b : Int = 1
+val b : Int = 1
+val b : Int = 1
+
+fun foo() {} // and here too
+fun foo() {} // and here
+fun foo() {} // and here
+fun foo() {} // and here
+
+fun bar() {} // and here
+fun bar() {} // and here
+fun bar() {} // and here
+
+class A {
+    val a : Int = 1
+    val a : Int = 1
+    val a : Int = 1
+
+    val b : Int = 1
+    val b : Int = 1
+    val b : Int = 1
+    val b : Int = 1
+
+    fun foo() {} // and here too
+    fun foo() {} // and here
+    fun foo() {} // and here
+    fun foo() {} // and here
+
+    fun bar() {} // and here
+    fun bar() {} // and here
+    fun bar() {} // and here
+}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByInnerClassConstructor.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByInnerClassConstructor.fir.kt
new file mode 100644
index 00000000000..946a4f9e593
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByInnerClassConstructor.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class Outer {
+    inner class Test1
+    inner class Test2(val x: Int)
+    inner class Test3(val x: Any)
+    inner class Test4<T>(val x: T)
+    inner class Test5(val x: Int) {
+        constructor() : this(0)
+        private constructor(z: String) : this(z.length)
+    }
+
+    class TestNested
+
+    internal class TestInternal
+    protected class TestProtected
+    private class TestPrivate
+}
+
+fun Outer.Test1() {}
+fun Outer.Test2(x: Int) {}
+fun Outer.Test3(x: String) {}
+fun <T> Outer.Test3(x: T) {}
+fun <T : Number> Outer.Test4(x: T) {}
+fun Outer.Test5() {}
+fun Outer.Test5(z: String) {}
+
+fun Outer.TestNested() {}
+fun Outer.TestInternal() {}
+fun Outer.TestProtected() {}
+fun Outer.TestPrivate() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByMemberFun.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByMemberFun.fir.kt
new file mode 100644
index 00000000000..6780abb07f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByMemberFun.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Test1 {
+    fun test1() {}
+}
+fun Test1.test1() {}
+
+interface Test2 {
+    fun test2(x: String) {}
+}
+fun Test2.test2(x: Any) {}
+
+interface Test3 {
+    fun test3(x: Any) {}
+}
+fun Test3.test3(x: String) {}
+fun <T : Any?> Test3.test3(x: T) {}
+
+interface Test4 {
+    fun <T> test4(x: T) {}
+}
+fun Test4.test4(x: String) {}
+
+interface Test5 {
+    fun <T> test5(x: T) {}
+}
+fun <T : Number> Test5.test5(x: T) {}
+
+interface Test6 {
+    fun <T : List<Any>> test6(x: T) {}
+}
+fun <T : Set<Any>> Test6.test6(x: T) {}
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByMemberPropertyWithInvoke.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByMemberPropertyWithInvoke.fir.kt
new file mode 100644
index 00000000000..aad3ff63313
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedByMemberPropertyWithInvoke.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface WithInvoke {
+    operator fun invoke()
+    operator fun invoke(s: String)
+    operator fun <T> invoke(x: T, y: Int)
+    fun invoke(i: Int)
+}
+
+interface Test1 {
+    val test1: WithInvoke
+}
+
+fun Test1.test1() {}
+fun Test1.test1(s: String) {}
+fun Test1.test1(i: Int) {}
+fun Test1.test1(x: Any, y: Int) {}
+fun <T : Number> Test1.test1(x: T, y: Int) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedBySynthesizedMemberFun.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedBySynthesizedMemberFun.fir.kt
new file mode 100644
index 00000000000..0c85c304347
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunShadowedBySynthesizedMemberFun.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+data class DataClass(val x: Int)
+
+fun DataClass.component1() = 42
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunVsMemberExtensionFun.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunVsMemberExtensionFun.fir.kt
new file mode 100644
index 00000000000..8298c498e70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionFunVsMemberExtensionFun.fir.kt
@@ -0,0 +1,5 @@
+class C {
+    fun Int.foo() {}
+}
+
+fun C.foo() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionOnErrorType.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionOnErrorType.fir.kt
new file mode 100644
index 00000000000..10292f79764
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionOnErrorType.fir.kt
@@ -0,0 +1,7 @@
+interface G<T> {
+    fun foo()
+    val bar: Int
+}
+
+fun G.foo() {}
+val G.bar: Int get() = 42
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionOnNullableReceiver.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionOnNullableReceiver.fir.kt
new file mode 100644
index 00000000000..796aee5f4e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionOnNullableReceiver.fir.kt
@@ -0,0 +1,7 @@
+interface Test {
+    fun foo()
+    val bar: Int
+}
+
+fun Test?.foo() {}
+val Test?.bar: Int get() = 42
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionPropertyShadowedByMemberProperty.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionPropertyShadowedByMemberProperty.fir.kt
new file mode 100644
index 00000000000..08b03b7803b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionPropertyShadowedByMemberProperty.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Test1 {
+    val test1: Int
+}
+val Test1.test1: Int get() = 42
+
+interface Test2 {
+    var test2: Int
+}
+val Test2.test2: Int get() = 42
+
+interface Test3 {
+    val test3: Int
+}
+var Test3.test3: Int get() = 42; set(v) {}
+
+interface Test4 {
+    val test4: Int
+}
+var Test4.test4: Int get() = 42; set(v) {}
+
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionShadowedByDelegatedMember.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionShadowedByDelegatedMember.fir.kt
new file mode 100644
index 00000000000..eb9374ad41e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionShadowedByDelegatedMember.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface IBase {
+    fun foo()
+    val bar: Int
+}
+
+object Impl : IBase {
+    override fun foo() {}
+    override val bar: Int get() = 42
+}
+
+object Test : IBase by Impl
+
+fun Test.foo() {}
+val Test.bar: Int get() = 42
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionVsNonPublicMember.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionVsNonPublicMember.fir.kt
new file mode 100644
index 00000000000..ba1d38269dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/extensionVsNonPublicMember.fir.kt
@@ -0,0 +1,47 @@
+class WithPublicInvoke {
+    public operator fun invoke() {}
+}
+
+class WithInternalInvoke {
+    internal operator fun invoke() {}
+}
+
+class WithProtectedInvoke {
+    protected operator fun invoke() {}
+}
+
+class WithPrivateInvoke {
+    private operator fun invoke() {}
+}
+
+class Test {
+    public fun publicFoo() {}
+    internal fun internalFoo() {}
+    protected fun protectedFoo() {}
+    private fun privateFoo() {}
+
+    public val publicVal = 42
+    internal val internalVal = 42
+    protected val protectedVal = 42
+    private val privateVal = 42
+
+    public val withPublicInvoke = WithPublicInvoke()
+    public val withInternalInvoke = WithInternalInvoke()
+    public val withProtectedInvoke = WithProtectedInvoke()
+    public val withPrivateInvoke = WithPrivateInvoke()
+}
+
+private fun Test.publicFoo() {}
+fun Test.internalFoo() {}
+fun Test.protectedFoo() {}
+fun Test.privateFoo() {}
+
+val Test.publicVal: Int get() = 42
+val Test.internalVal: Int get() = 42
+val Test.protectedVal: Int get() = 42
+val Test.privateVal: Int get() = 42
+
+fun Test.withPublicInvoke() {}
+fun Test.wihtInternalInvoke() {}
+fun Test.withProtectedInvoke() {}
+fun Test.withPrivateInvoke() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/infixExtensionVsNonInfixMember.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/infixExtensionVsNonInfixMember.fir.kt
new file mode 100644
index 00000000000..40ec24b1d1b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/infixExtensionVsNonInfixMember.fir.kt
@@ -0,0 +1,7 @@
+interface IFoo {
+    fun foo(i: Int): Int
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun bar(i: Int): Int<!>
+}
+
+infix fun IFoo.foo(i: Int) = i
+infix fun IFoo.bar(i: Int) = i
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/localExtensionShadowedByMember.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/localExtensionShadowedByMember.fir.kt
new file mode 100644
index 00000000000..30a1f33716a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/localExtensionShadowedByMember.fir.kt
@@ -0,0 +1,7 @@
+interface IFoo {
+    fun foo()
+}
+
+fun outer() {
+    fun IFoo.foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/memberExtensionShadowedByMember.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/memberExtensionShadowedByMember.fir.kt
new file mode 100644
index 00000000000..f21accfe873
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/memberExtensionShadowedByMember.fir.kt
@@ -0,0 +1,9 @@
+interface IFooBar {
+    fun foo()
+    val bar: Int
+}
+
+class Host {
+    fun IFooBar.foo() {}
+    val IFooBar.bar: Int get() = 42
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/operatorExtensionVsNonOperatorMember.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/operatorExtensionVsNonOperatorMember.fir.kt
new file mode 100644
index 00000000000..a373cd38dcc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/shadowedExtension/operatorExtensionVsNonOperatorMember.fir.kt
@@ -0,0 +1,7 @@
+interface Test {
+    fun invoke()
+    operator fun invoke(i: Int): Int
+}
+
+operator fun Test.invoke() {}
+operator fun Test.invoke(i: Int) = i
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/redeclarations/typeParameterWithTwoBounds.fir.kt b/compiler/testData/diagnostics/tests/redeclarations/typeParameterWithTwoBounds.fir.kt
new file mode 100644
index 00000000000..ad354abd6b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/redeclarations/typeParameterWithTwoBounds.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface Foo
+interface Bar
+
+fun <T> foo(x: T): T where T: Foo, T: Bar {null!!}
+fun foo(x: Foo): Foo {null!!}
+fun foo(x: Bar): Bar {null!!}
diff --git a/compiler/testData/diagnostics/tests/reflection/noReflectionInClassPath.fir.kt b/compiler/testData/diagnostics/tests/reflection/noReflectionInClassPath.fir.kt
new file mode 100644
index 00000000000..0eb9f3505de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/reflection/noReflectionInClassPath.fir.kt
@@ -0,0 +1,62 @@
+import kotlin.reflect.*
+
+class Foo(val prop: Any) {
+    fun func() {}
+}
+
+fun n01() = Foo::prop
+fun n02() = Foo::func
+fun n03() = Foo::class
+fun n04(p: KProperty0<Int>) = p.get()
+fun n05(p: KMutableProperty0<String>) = p.set("")
+fun n07(p: KFunction<String>) = p.name
+fun n08(p: KProperty1<String, Int>) = p.get("")
+fun n09(p: KProperty2<String, String, Int>) = p.get("", "")
+fun n10() = (Foo::func).invoke(Foo(""))
+fun n11() = (Foo::func)(Foo(""))
+
+fun y01() = Foo::prop.getter
+fun y02() = Foo::class.members
+fun y03() = Foo::class.simpleName
+fun y04() = Foo::class.<!UNRESOLVED_REFERENCE!>properties<!>
+
+fun <T : Any> kclass(k: KClass<*>, kt: KClass<T>) {
+    k.simpleName
+    k.qualifiedName
+    k.members
+    k.constructors
+    k.nestedClasses
+    k.objectInstance
+    k.typeParameters
+    k.supertypes
+    k.visibility
+    k.isFinal
+    k.isOpen
+    k.isAbstract
+    k.isSealed
+    k.isData
+    k.isInner
+    k.isCompanion
+
+    k.annotations
+    k.isInstance(42)
+
+    k == kt
+    k.hashCode()
+    k.toString()
+}
+
+fun ktype(t: KType, t2: KType) {
+    t.classifier
+    t.arguments
+    t.isMarkedNullable
+    t.annotations
+
+    t == t2
+    t.hashCode()
+    t.toString()
+
+    KTypeProjection.Companion.covariant(t)
+    KTypeProjection.STAR
+    KTypeProjection(KVariance.IN, t)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/AmbiguityOnLazyTypeComputation.fir.kt b/compiler/testData/diagnostics/tests/regressions/AmbiguityOnLazyTypeComputation.fir.kt
new file mode 100644
index 00000000000..68cd9854c50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/AmbiguityOnLazyTypeComputation.fir.kt
@@ -0,0 +1,12 @@
+// One of the two passes is making a scope and turning vals into functions
+// See KT-76
+
+package x
+
+val b : Foo = Foo()
+val a1 = b.compareTo(2)
+
+class Foo() {
+  fun compareTo(other : Byte)   : Int = 0
+  fun compareTo(other : Char)   : Int = 0
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/AssignmentsUnderOperators.fir.kt b/compiler/testData/diagnostics/tests/regressions/AssignmentsUnderOperators.fir.kt
new file mode 100644
index 00000000000..b942565037b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/AssignmentsUnderOperators.fir.kt
@@ -0,0 +1,6 @@
+fun test() {
+  var a : Any? = null
+  if (a is Any) else a = null;
+  while (a is Any) a = null
+  while (true) a = null
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/CoercionToUnit.fir.kt b/compiler/testData/diagnostics/tests/regressions/CoercionToUnit.fir.kt
new file mode 100644
index 00000000000..575b3387c25
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/CoercionToUnit.fir.kt
@@ -0,0 +1,9 @@
+fun foo(u : Unit) : Int = 1
+
+fun test() : Int {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1)
+    val a : () -> Unit = {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(1)
+    }
+    return 1
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/DoubleDefine.fir.kt b/compiler/testData/diagnostics/tests/regressions/DoubleDefine.fir.kt
new file mode 100644
index 00000000000..8e63f0f3c10
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/DoubleDefine.fir.kt
@@ -0,0 +1,65 @@
+import java.util.*
+
+import java.io.*
+
+fun takeFirst(expr: StringBuilder): Char {
+  val c = expr.get(0)
+  expr.deleteCharAt(0)
+  return c
+}
+
+fun evaluateArg(expr: CharSequence, numbers: ArrayList<Int>): Int {
+  if (expr.length == 0) throw Exception("Syntax error: Character expected");
+  val c = <!INAPPLICABLE_CANDIDATE!>takeFirst<!>(expr)
+  if (c >= '0' && c <= '9') {
+    val n = c <!UNRESOLVED_REFERENCE!>-<!> '0'
+    if (!numbers.contains(n)) throw Exception("You used incorrect number: " + n)
+    numbers.<!AMBIGUITY!>remove<!>(n)
+    return n
+  }
+  throw Exception("Syntax error: Unrecognized character " + c)
+}
+
+fun evaluateAdd(expr: StringBuilder, numbers: ArrayList<Int>): Int {
+  val lhs = evaluateArg(expr, numbers)
+  if (expr.length > 0) {
+
+  }
+  return lhs
+}
+
+fun evaluate(expr: StringBuilder, numbers: ArrayList<Int>): Int {
+  val lhs = evaluateAdd(expr, numbers)
+  if (expr.length > 0) {
+    val c = expr.get(0)
+    expr.deleteCharAt(0)
+  }
+  return lhs
+}
+
+fun main() {
+  System.out.println("24 game")
+  val numbers = ArrayList<Int>(4)
+  val rnd = Random();
+  val prompt = StringBuilder()
+  for(i in 0..3) {
+    val n = rnd.nextInt(9) + 1
+    numbers.add(n)
+    if (i > 0) prompt.append(" ");
+    prompt.append(n)
+  }
+  System.out.println("Your numbers: " + prompt)
+  System.out.println("Enter your expression:")
+  val reader = BufferedReader(InputStreamReader(System.`in`))
+  val expr = StringBuilder(reader.readLine()!!)
+  try {
+    val result = evaluate(expr, numbers)
+    if (result != 24)
+      System.out.println("Sorry, that's " + result)
+    else
+      System.out.println("You won!");
+  }
+  catch(e: Throwable) {
+    System.out.println(e.message)
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/ErrorsOnIbjectExpressionsAsParameters.fir.kt b/compiler/testData/diagnostics/tests/regressions/ErrorsOnIbjectExpressionsAsParameters.fir.kt
new file mode 100644
index 00000000000..a773dd1bbf1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ErrorsOnIbjectExpressionsAsParameters.fir.kt
@@ -0,0 +1,5 @@
+fun foo(a : Any) {}
+
+fun test() {
+  foo(object {});
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet11.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet11.fir.kt
new file mode 100644
index 00000000000..10db1b15a24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet11.fir.kt
@@ -0,0 +1,4 @@
+// JET-11 Redeclaration & Forward reference for classes cause an exception
+open class NoC
+class NoC1 : NoC()
+open class NoC
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet121.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet121.fir.kt
new file mode 100644
index 00000000000..c3eddacc387
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet121.fir.kt
@@ -0,0 +1,14 @@
+package jet121
+
+fun box() : String {
+val answer = apply("OK") {
+  get(0)
+  length
+}
+
+return if (answer == 2) "OK" else "FAIL"
+}
+
+fun apply(arg:String, f :  String.() -> Int) : Int {
+  return arg.<!UNRESOLVED_REFERENCE!>f<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet124.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet124.fir.kt
new file mode 100644
index 00000000000..6fa400a1acc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet124.fir.kt
@@ -0,0 +1,8 @@
+fun foo1() :  (Int) -> Int = { x: Int -> x }
+
+fun foo() {
+  val h :  (Int) -> Int = foo1();
+  h(1)
+  val m :  (Int) -> Int = {a : Int -> 1}//foo1()
+  m(1)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet169.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet169.fir.kt
new file mode 100644
index 00000000000..35f484e4332
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet169.fir.kt
@@ -0,0 +1,8 @@
+fun set(key : String, value : String) {
+  val a : String? = ""
+  when (a) {
+    "" -> a.get(0)
+    is String, is Any -> a.compareTo("")
+    else -> a.toString()
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet17.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet17.fir.kt
new file mode 100644
index 00000000000..d9fb94fa6c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet17.fir.kt
@@ -0,0 +1,6 @@
+// JET-17 Do not infer property types by the initializer before the containing scope is ready
+
+class WithC() {
+  val a = 1
+  val b = a
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet183-1.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet183-1.fir.kt
new file mode 100644
index 00000000000..8103acc9fd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet183-1.fir.kt
@@ -0,0 +1,21 @@
+enum class ProtocolState {
+  WAITING {
+    override fun signal() = ProtocolState.TALKING
+  },
+
+  TALKING {
+    override fun signal() = ProtocolState.WAITING
+  };
+
+  abstract fun signal() : ProtocolState
+}
+
+
+fun box(): String {
+   var x: ProtocolState = ProtocolState.WAITING
+   x = x.signal()
+   if (x != ProtocolState.TALKING) return "fail 1"
+   x = x.signal()
+   if (x != ProtocolState.WAITING) return "fail 2"
+   return "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet183.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet183.fir.kt
new file mode 100644
index 00000000000..65c0a2efb39
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet183.fir.kt
@@ -0,0 +1,15 @@
+enum class ProtocolState {
+  WAITING {
+    override fun signal() = ProtocolState.TALKING
+  },
+
+  TALKING {
+    override fun signal() = ProtocolState.WAITING
+  };
+
+  abstract fun signal() : ProtocolState
+}
+
+fun box() {
+   val x: ProtocolState = ProtocolState.WAITING
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet53.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet53.fir.kt
new file mode 100644
index 00000000000..0703aa50dd6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet53.fir.kt
@@ -0,0 +1,5 @@
+// !CHECK_TYPE
+
+import java.util.Collections
+
+val ab = checkSubtype<List<Int>?>(Collections.emptyList<Int>())
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet67.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet67.fir.kt
new file mode 100644
index 00000000000..94549ab8df9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet67.fir.kt
@@ -0,0 +1,4 @@
+abstract class XXX {
+  abstract val a : Int get
+
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet68.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet68.fir.kt
new file mode 100644
index 00000000000..40348b96052
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet68.fir.kt
@@ -0,0 +1,11 @@
+class Foo()
+
+fun test() {
+  val f : Foo? = null
+  if (f == null) {
+
+  }
+  if (f != null) {
+
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet69.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet69.fir.kt
new file mode 100644
index 00000000000..8c9d412b28c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet69.fir.kt
@@ -0,0 +1,10 @@
+class Command() {}
+
+fun parse(cmd: String): Command? { return null  }
+
+fun Any.equals(other : Any?) : Boolean = this === other
+
+fun main() {
+    val command = parse("")
+    if (command == null) 1 // error on this line, but must be OK
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet72.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet72.fir.kt
new file mode 100644
index 00000000000..accd324d8b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet72.fir.kt
@@ -0,0 +1,18 @@
+// JET-72 Type inference doesn't work when iterating over ArrayList
+
+import java.util.ArrayList
+
+abstract class Item(val room: Object) {
+   abstract val name : String
+}
+
+val items: ArrayList<Item> = ArrayList<Item>()
+
+fun test(room : Object) {
+  for(item: Item? in items) {
+    if (item?.room === room) {
+      // item?.room is not null
+      System.out.println("You see " + item?.name)
+    }
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet81.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet81.fir.kt
new file mode 100644
index 00000000000..c1e59e0a376
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/Jet81.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+// JET-81 Assertion fails when processing self-referring anonymous objects
+
+class Test {
+  private val y = object {
+    val a = y;
+  }
+
+  val z = y.<!UNRESOLVED_REFERENCE!>a<!>;
+
+}
+
+object A {
+  val x = A
+}
+
+class Test2 {
+  private val a = object {
+    init {
+      b + 1
+    }
+    val x = b
+    val y = 1
+  }
+
+  val b = a.x
+  val c = a.y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/OrphanStarProjection.fir.kt b/compiler/testData/diagnostics/tests/regressions/OrphanStarProjection.fir.kt
new file mode 100644
index 00000000000..a7e6c9f79df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/OrphanStarProjection.fir.kt
@@ -0,0 +1,3 @@
+class B {}
+
+val b : B<*> = 1
diff --git a/compiler/testData/diagnostics/tests/regressions/OutProjections.fir.kt b/compiler/testData/diagnostics/tests/regressions/OutProjections.fir.kt
new file mode 100644
index 00000000000..d26f8e694c9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/OutProjections.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+class Point() {
+}
+
+class G<T>() {}
+
+fun <T> f(expression : T) : G<out T> = G<T>()
+
+
+fun foo() : G<Point> {
+  val p = Point()
+  return f<Point>(p)
+}
+
+class Out<out T>() {}
+
+fun <T> fout(expression : T) : Out<out T> = Out<T>()
+
+fun fooout() : Out<Point> {
+  val p = Point();
+  return fout<Point>(p);
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/OverrideResolution.fir.kt b/compiler/testData/diagnostics/tests/regressions/OverrideResolution.fir.kt
new file mode 100644
index 00000000000..26a262dc8c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/OverrideResolution.fir.kt
@@ -0,0 +1,16 @@
+fun box(c : C) {
+    val a : C = c
+    a.foo()
+}
+
+open class A {
+    open fun foo() {}
+}
+
+open class B : A() {
+    override fun foo() {}
+}
+
+open class C : B() {
+    override fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/SpecififcityByReceiver.fir.kt b/compiler/testData/diagnostics/tests/regressions/SpecififcityByReceiver.fir.kt
new file mode 100644
index 00000000000..4133e61a048
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/SpecififcityByReceiver.fir.kt
@@ -0,0 +1,9 @@
+fun Any.equals(other : Any?) : Boolean = true
+
+fun main() {
+
+    val command : Any = 1
+
+    command?.equals(null)
+    command.equals(null)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.fir.kt b/compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.fir.kt
new file mode 100644
index 00000000000..ba05c3f1ffe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/TypeMismatchOnUnaryOperations.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+fun main() {
+    val a : Int? = null;
+    var v = 1
+    val b : String = v;
+    val f : String = a!!;
+    val g : String = v++;
+    val g1 : String = ++v;
+    val h : String = v--;
+    val h1 : String = --v;
+    val i : String = !true;
+    val j : String = foo@ true;
+    val k : String = foo@ bar@ true;
+    val l : String = -1;
+    val m : String = +1;
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/TypeParameterAsASupertype.fir.kt b/compiler/testData/diagnostics/tests/regressions/TypeParameterAsASupertype.fir.kt
new file mode 100644
index 00000000000..6c0c8795e61
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/TypeParameterAsASupertype.fir.kt
@@ -0,0 +1 @@
+class A<T> : <!OTHER_ERROR!>T<!> {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/UnavaliableQualifiedThis.fir.kt b/compiler/testData/diagnostics/tests/regressions/UnavaliableQualifiedThis.fir.kt
new file mode 100644
index 00000000000..49cf7add2a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/UnavaliableQualifiedThis.fir.kt
@@ -0,0 +1,13 @@
+interface Iterator<out T> {
+ fun next() : T
+ val hasNext : Boolean
+
+ fun <R> map(transform: (element: T) -> R) : Iterator<R> =
+    object : Iterator<R> {
+      override fun next() : R = transform(this@map.<!UNRESOLVED_REFERENCE!>next<!>())
+
+      override val hasNext : Boolean
+        // There's no 'this' associated with the map() function, only this of the Iterator class
+        get() = this@map.<!UNRESOLVED_REFERENCE!>hasNext<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/WrongTraceInCallResolver.fir.kt b/compiler/testData/diagnostics/tests/regressions/WrongTraceInCallResolver.fir.kt
new file mode 100644
index 00000000000..bca7a4babd4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/WrongTraceInCallResolver.fir.kt
@@ -0,0 +1,9 @@
+open class Foo {}
+open class Bar {}
+
+fun <T : Bar, T1> foo(x : Int) {}
+fun <T1, T : Foo> foo(x : Long) {}
+
+fun f(): Unit {
+    <!INAPPLICABLE_CANDIDATE!>foo<!><Int, Int>(1)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/correctResultSubstitutorForErrorCandidate.fir.kt b/compiler/testData/diagnostics/tests/regressions/correctResultSubstitutorForErrorCandidate.fir.kt
new file mode 100644
index 00000000000..66b4444b6da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/correctResultSubstitutorForErrorCandidate.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun test(a: Int, b: Boolean) {
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(a.<!INAPPLICABLE_CANDIDATE!>foo<!>(b))
+}
+
+fun <T, R> T.foo(l: (T) -> R): R = TODO()
+
+fun <S> bar(a: S) {}
diff --git a/compiler/testData/diagnostics/tests/regressions/delegationWithReceiver.fir.kt b/compiler/testData/diagnostics/tests/regressions/delegationWithReceiver.fir.kt
new file mode 100644
index 00000000000..efc97fc4e05
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/delegationWithReceiver.fir.kt
@@ -0,0 +1,10 @@
+import kotlin.reflect.KProperty
+
+class MyMetadata<in T, R>(val default: R) {
+    operator fun getValue(thisRef: T, desc: KProperty<*>): R = TODO()
+    operator fun setValue(thisRef: T, desc: KProperty<*>, value: R) {}
+}
+
+interface Something
+class MyReceiver
+var MyReceiver.something: Something? by MyMetadata(default = null)
diff --git a/compiler/testData/diagnostics/tests/regressions/ea40964.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea40964.fir.kt
new file mode 100644
index 00000000000..0410edc71ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea40964.fir.kt
@@ -0,0 +1,8 @@
+package checkFiles
+
+import java.util.HashMap
+
+fun main() {
+    val hashMap = HashMap<String, String>()
+    hashMap[<!SYNTAX!><!>]
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/ea43298.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea43298.fir.kt
new file mode 100644
index 00000000000..7a68643cae8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea43298.fir.kt
@@ -0,0 +1,3 @@
+import A.<!SYNTAX!><!>;
+
+class A
diff --git a/compiler/testData/diagnostics/tests/regressions/ea53340.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea53340.fir.kt
new file mode 100644
index 00000000000..7205d13137b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea53340.fir.kt
@@ -0,0 +1,7 @@
+class A : Function0<Int> {
+    override fun invoke(): Int = 1
+}
+
+fun main() {
+    A()()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/ea65509.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea65509.fir.kt
new file mode 100644
index 00000000000..b636cc4d0db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea65509.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -FUNCTION_DECLARATION_WITH_NO_NAME
+class ClassB() {
+    private inner class ClassC: <!SYNTAX!>super<!><!SYNTAX!>.<!>@ClassA()<!SYNTAX!><!> {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/ea66984.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea66984.fir.kt
new file mode 100644
index 00000000000..c26e7fc62bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea66984.fir.kt
@@ -0,0 +1,2 @@
+// !DIAGNOSTICS: -NO_VALUE_FOR_PARAMETER
+class Tree<T>(T <!SYNTAX!>element<!>, <!SYNTAX!><!>Tree<T><!SYNTAX!><!> left<!SYNTAX!><!>, <!SYNTAX!><!>Tree<T><!SYNTAX!><!> right<!SYNTAX!><!>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/ea69735.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea69735.fir.kt
new file mode 100644
index 00000000000..c7fd82de1cd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea69735.fir.kt
@@ -0,0 +1,5 @@
+enum class MyEnum {
+    // Here we have a problem 
+    // while checking on a deprecated super constructor
+    FIRST<!SYNTAX!><!SYNTAX!><!>:<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/ea72837.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea72837.fir.kt
new file mode 100644
index 00000000000..62428aab796
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea72837.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun <T> g(x: T) = 1
+fun h(x: () -> Unit) = 1
+
+fun foo() {
+    <!UNRESOLVED_REFERENCE!>f<!>(::<!SYNTAX!><!>)
+    <!INAPPLICABLE_CANDIDATE!>g<!>(::<!SYNTAX!><!>)
+    <!INAPPLICABLE_CANDIDATE!>h<!>(::<!SYNTAX!><!>)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/ea76264.fir.kt b/compiler/testData/diagnostics/tests/regressions/ea76264.fir.kt
new file mode 100644
index 00000000000..aab934787db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/ea76264.fir.kt
@@ -0,0 +1,4 @@
+// StackOverflow
+val p = ::p
+
+fun foo() = ::foo
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/intchar.fir.kt b/compiler/testData/diagnostics/tests/regressions/intchar.fir.kt
new file mode 100644
index 00000000000..edfb8c134cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/intchar.fir.kt
@@ -0,0 +1 @@
+val x: Char = '1'.plus(1)
diff --git a/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBound.fir.kt b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBound.fir.kt
new file mode 100644
index 00000000000..1b4dd0f6705
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBound.fir.kt
@@ -0,0 +1,3 @@
+// !DIAGNOSTICS: -MUST_BE_INITIALIZED -TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER
+fun <T: T?> foo() {}
+val <T: T?> prop
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundInClass.fir.kt b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundInClass.fir.kt
new file mode 100644
index 00000000000..c826cffed8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundInClass.fir.kt
@@ -0,0 +1 @@
+class MyClass<T: T?>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundInClassNotNull.fir.kt b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundInClassNotNull.fir.kt
new file mode 100644
index 00000000000..eef2a5ca164
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundInClassNotNull.fir.kt
@@ -0,0 +1 @@
+class MyClass<T: T>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundLocal.fir.kt b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundLocal.fir.kt
new file mode 100644
index 00000000000..e3a2e94fcd8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundLocal.fir.kt
@@ -0,0 +1,5 @@
+// !WITH_NEW_INFERENCE
+fun bar() {
+    fun <T: T?> foo() {}
+    foo()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundMember.fir.kt b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundMember.fir.kt
new file mode 100644
index 00000000000..7d7a00b32d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundMember.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -MUST_BE_INITIALIZED_OR_BE_ABSTRACT -TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER
+class My {
+    fun <T: T?> foo() {}
+    val <T: T?> prop: T
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundNotNull.fir.kt b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundNotNull.fir.kt
new file mode 100644
index 00000000000..7d0c85088b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/itselfAsUpperBoundNotNull.fir.kt
@@ -0,0 +1,3 @@
+// !DIAGNOSTICS: -MUST_BE_INITIALIZED -TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER
+fun <T: T> foo() {}
+val <T: T?> prop: T
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt10243.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt10243.fir.kt
new file mode 100644
index 00000000000..eb1e3b5304f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt10243.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+val f: Boolean = true
+private fun doUpdateRegularTasks() {
+    try {
+        while (f) {
+            val xmlText = <!UNRESOLVED_REFERENCE!>getText<!>()
+            if (xmlText == null) {}
+            else {
+                xmlText.<!UNRESOLVED_REFERENCE!>value<!> = 0 // !!!
+            }
+        }
+
+    }
+    finally {
+        fun execute() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt10243a.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt10243a.fir.kt
new file mode 100644
index 00000000000..e710a2b9cf8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt10243a.fir.kt
@@ -0,0 +1,11 @@
+var x: Int
+fun foo(f: Boolean) {
+    try {
+        if (f) {
+            x = 0
+        }
+    }
+    finally {
+        fun bar() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt10633.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt10633.fir.kt
new file mode 100644
index 00000000000..0b14f8f5049
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt10633.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+var count = 0
+
+operator fun Int.get(s: Int): Int {
+    count++
+    return this + s
+}
+
+operator fun Int.set(s: Int, x: String = "", z: Int) {
+}
+
+fun main() {
+    <!INAPPLICABLE_CANDIDATE!>1[2] = 1<!>
+    1.set(2, z = 1)
+    1[2] += 1
+
+    1.<!INAPPLICABLE_CANDIDATE!>set<!>(2, 1)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt10824.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt10824.fir.kt
new file mode 100644
index 00000000000..f83396251b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt10824.fir.kt
@@ -0,0 +1,52 @@
+// See KT-10824: Smart cast depending on control flow does not work inside `if`
+class A
+fun foo(a: A?, aOther: A?): A {
+    return if (a == null) {
+        A()
+    }
+    else {
+        var newA = aOther
+        if (newA == null) {
+            newA = A()
+        }
+        newA
+    }
+}
+fun bar(a: A?, aOther: A?): A {
+    return if (a == null) {
+        A()
+    }
+    else {
+        if (aOther == null) {
+            return A()
+        }
+
+        aOther
+    }
+}
+fun foo1(a: A?, aOther: A?): A {
+    val result = if (a == null) {
+        A()
+    }
+    else {
+        var newA = aOther
+        if (newA == null) {
+            newA = A()
+        }
+        newA
+    }
+    return result
+}
+fun bar1(a: A?, aOther: A?): A {
+    val result = if (a == null) {
+        A()
+    }
+    else {
+        if (aOther == null) {
+            return A()
+        }
+
+        aOther
+    }
+    return result
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt10843.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt10843.fir.kt
new file mode 100644
index 00000000000..c34a25f506f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt10843.fir.kt
@@ -0,0 +1,8 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+// See EA-76890 / KT-10843: NPE during analysis
+fun lambda(x : Int?) = x?.<!UNRESOLVED_REFERENCE!>let<!> <!UNRESOLVED_REFERENCE!>l<!> {
+    y ->
+    if (y > 0) return@l x
+    y
+}!!
diff --git a/compiler/testData/diagnostics/tests/regressions/kt127.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt127.fir.kt
new file mode 100644
index 00000000000..6e026f7ecf0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt127.fir.kt
@@ -0,0 +1,18 @@
+// KT-127 Support extension functions in when expressions
+
+class Foo() {}
+
+fun Any?.equals1(other : Any?) : Boolean = true
+
+fun main() {
+
+    val command : Foo? = null
+
+    // Commented for KT-621
+    // when (command) {
+    //   .equals(null) => 1; // must be resolved
+    //   ?.equals(null) => 1 // same here
+    // }
+    command.equals1(null)
+    command?.equals(null)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt128.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt128.fir.kt
new file mode 100644
index 00000000000..0225952f080
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt128.fir.kt
@@ -0,0 +1,12 @@
+// KT-128 Support passing only the last closure if all the other parameters have default values
+
+fun div(c : String = "", f : () -> Unit) {}
+fun f() {
+    div { // Nothing passed, but could have been...
+      // ...
+    }
+
+    div (c = "foo") { // More things could have been passed
+      // ...
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt13685.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt13685.fir.kt
new file mode 100644
index 00000000000..9d924b02776
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt13685.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNREACHABLE_CODE
+
+fun foo() {
+    val text: List<Any> = null!!
+    text.<!UNRESOLVED_REFERENCE!>map<!> <!UNRESOLVED_REFERENCE!>Any<!><!SYNTAX!>?<!>::toString
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt13954.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt13954.fir.kt
new file mode 100644
index 00000000000..d5a0c803542
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt13954.fir.kt
@@ -0,0 +1,26 @@
+// FILE: foo/A.kt
+
+package foo
+
+class A(val c: C)
+
+// FILE: foo/B.kt
+
+package foo
+
+class B {
+    interface D {
+        fun foo(): E
+    }
+
+    class E
+}
+
+// FILE: foo/C.java
+
+package foo;
+
+import static foo.B.D.*;
+
+@SuppressWarnings("RedundantTypeArguments")
+public class C {}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt14740.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt14740.fir.kt
new file mode 100644
index 00000000000..411e8dcbe5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt14740.fir.kt
@@ -0,0 +1,20 @@
+// FILE: Foo.java
+public abstract class Foo {
+
+    public interface Transformer<T, R> {}
+    public interface LifecycleTransformer<T> extends Transformer<T, T> {}
+
+    public class Observable<T> {
+        public <R> Observable<R> compose(Transformer<? super T, ? extends R> transformer) {
+            return null;
+        }
+    }
+
+
+    public final <T> LifecycleTransformer<T> bindToLifecycle() {
+        return null;
+    }
+}
+
+// FILE: 1.kt
+fun <T> Foo.Observable<T>.bindTo(a: Foo): Foo.Observable<T>  = compose(a.bindToLifecycle())
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt1489_1728.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt1489_1728.fir.kt
new file mode 100644
index 00000000000..8ce7619d2f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt1489_1728.fir.kt
@@ -0,0 +1,31 @@
+// !WITH_NEW_INFERENCE
+package kt606_dependents
+
+//KT-1489 Code analyzer fails with assertion
+interface AutoCloseable{
+    fun close()
+}
+
+class C {
+    class Resource : AutoCloseable {
+        override fun close() {
+            throw UnsupportedOperationException()
+        }
+    }
+
+    fun <X : AutoCloseable> foo(x : X, body : (X) -> Unit) {
+    }
+
+    fun p() : Resource? = null
+
+    fun bar() {
+        foo(p()) {
+
+        }
+    }
+}
+
+//KT-1728 Can't invoke extension property as a function
+
+val Int.ext : () -> Int get() = { 5 }
+val x = 1.ext()
diff --git a/compiler/testData/diagnostics/tests/regressions/kt1550.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt1550.fir.kt
new file mode 100644
index 00000000000..f9bf9dcf7b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt1550.fir.kt
@@ -0,0 +1,12 @@
+package foo
+
+import java.util.*
+
+fun main()
+{
+  val c = ArrayList<Int>()
+  c.add(3)
+  System.out.println(++(c[0]))
+  System.out.println((c[1])--)
+  System.out.println(-(c[2]))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt16086.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt16086.fir.kt
new file mode 100644
index 00000000000..54173a9811c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt16086.fir.kt
@@ -0,0 +1,21 @@
+// JAVAC_EXPECTED_FILE
+// FILE: com/winterbe/domain/IEntity.java
+package com.winterbe.domain;
+import com.winterbe.observer.ObserverSupport;
+
+public interface IEntity {
+    ObserverSupport getObserverSupport();
+}
+
+// FILE: 1.kt
+package com.winterbe.observer
+import com.winterbe.domain.IEntity
+
+abstract class Observer : List<IEntity>
+
+
+// FILE: 2.kt
+package com.winterbe.observer
+import com.winterbe.domain.IEntity
+
+class ObserverSupport<T : IEntity>(private val observers: List<Observer>)
diff --git a/compiler/testData/diagnostics/tests/regressions/kt16086_2.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt16086_2.fir.kt
new file mode 100644
index 00000000000..abd3f382969
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt16086_2.fir.kt
@@ -0,0 +1,13 @@
+// FILE: 1.kt
+package a
+import b.ObserverSupport
+
+interface IEntity
+
+fun IEntity(f: ObserverSupport<IEntity>) {}
+
+// FILE: 2.kt
+package b
+import a.IEntity
+
+class ObserverSupport<T : IEntity>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.fir.kt
new file mode 100644
index 00000000000..9571fa7e0e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.fir.kt
@@ -0,0 +1,12 @@
+// FULL_JDK
+// SKIP_TXT
+
+package test
+
+import javax.swing.JFrame
+
+class KFrame() : JFrame() {
+    init {
+        val x = this.rootPaneCheckingEnabled // make sure field is visible
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt1647.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt1647.fir.kt
new file mode 100644
index 00000000000..dc0b3e26c38
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt1647.fir.kt
@@ -0,0 +1,11 @@
+// KT-1647 Pattern matching doesn't work with generics
+
+open class Abs
+class Bar : Abs()
+
+fun <F : Abs> patternMatchingAndGenerics(arg : F) : String {
+    if(arg is Bar){
+      return "Bar";
+    }
+    return "else";
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt1736.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt1736.fir.kt
new file mode 100644
index 00000000000..d81fdfcd2b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt1736.fir.kt
@@ -0,0 +1,10 @@
+//KT-1736 AssertionError in CallResolver
+
+package kt1736
+
+object Obj {
+    fun method() {
+    }
+}
+
+val x = Obj.<!INAPPLICABLE_CANDIDATE!>method<!>{ -> }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt174.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt174.fir.kt
new file mode 100644
index 00000000000..6c8c0e638c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt174.fir.kt
@@ -0,0 +1,7 @@
+// KT-174 Nullability info for extension function receivers
+interface Tree {}
+
+fun Any?.TreeValue() : Tree {
+  if (this is Tree) return this
+    throw Exception()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt201.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt201.fir.kt
new file mode 100644
index 00000000000..99e9475c106
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt201.fir.kt
@@ -0,0 +1,8 @@
+// KT-201 Allow to call extension with nullable receiver with a '.'
+
+fun <T : Any> T?.npe() : T = if (this == null) throw NullPointerException() else this
+
+fun foo() {
+  val i : Int? = 1
+  i.npe() // error!
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt235.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt235.fir.kt
new file mode 100644
index 00000000000..f404c6c8a8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt235.fir.kt
@@ -0,0 +1,49 @@
+//KT-235 Illegal assignment return type
+
+package kt235
+
+fun main() {
+    val array = MyArray()
+    val f: () -> String = {
+        array[2] = 23 //error: Type mismatch: inferred type is Int (!!!) but String was expected
+    }
+    val g: () -> String = {
+        var x = 1
+        x += 2  //no error, but it should be here
+    }
+    val h: () -> String = {
+        var x = 1
+        x = 2  //the same
+    }
+    val array1 = MyArray1()
+    val i: () -> String = {
+        array1[2] = 23
+    }
+
+    val fi: () -> String = {
+        array[2] = 23
+    }
+    val gi: () -> String = {
+        var x = 1
+        x += 21
+    }
+
+    var m: MyNumber = MyNumber()
+    val a: () -> MyNumber = {
+        m++
+    }
+}
+
+class MyArray() {
+    operator fun get(i: Int): Int = 1
+    operator fun set(i: Int, value: Int): Int = 1
+}
+
+class MyArray1() {
+    operator fun get(i: Int): Int = 1
+    operator fun set(i: Int, value: Int) {}
+}
+
+class MyNumber() {
+    operator fun inc(): MyNumber = MyNumber()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt2376.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt2376.fir.kt
new file mode 100644
index 00000000000..61acbc6a036
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt2376.fir.kt
@@ -0,0 +1,10 @@
+// FILE: main.kt
+//KT-2376 java.lang.Number should be visible in Kotlin as kotlin.Number
+fun main() {
+    Test().number(5.toInt())
+}
+
+// FILE: Test.java
+public class Test {
+    void number(Number n){}
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt24488.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt24488.fir.kt
new file mode 100644
index 00000000000..f454a2de1b0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt24488.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// SKIP_TXT
+
+class Bar {
+    val a: Array<String>? = null
+}
+
+fun foo(bar: Bar) = bar.a?.asIterable() ?: emptyArray()
+
+fun <T> Array<out T>.asIterable(): Iterable<T> = TODO()
+
+fun testFrontend() {
+    val bar = Bar()
+    foo(bar)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt251.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt251.fir.kt
new file mode 100644
index 00000000000..603b5de0d3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt251.fir.kt
@@ -0,0 +1,34 @@
+// !WITH_NEW_INFERENCE
+class A() {
+    var x: Int = 0
+        get() = "s"
+        set(value: String) {
+            field = value
+        }
+    val y: Int
+        get(): String = "s"
+    val z: Int
+        get() {
+            return "s"
+        }
+
+    var a: Any = 1
+        set(v: String) {
+            field = v
+        }
+    val b: Int
+        get(): Any = "s"
+    val c: Int
+        get() {
+            return 1
+        }
+    val d = 1
+        get() {
+            return field
+        }
+    val e = 1
+        get(): String {
+            return field
+        }
+
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt258.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt258.fir.kt
new file mode 100644
index 00000000000..7ea51cec00d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt258.fir.kt
@@ -0,0 +1,10 @@
+// KT-258 Support equality constraints in type inference
+
+import java.util.*
+
+fun test() {
+  val attributes : HashMap<String, String> = HashMap()
+  attributes["href"] = "1" // inference fails, but it shouldn't
+}
+
+operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) {}//= this.put(key, value)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt26-1.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt26-1.fir.kt
new file mode 100644
index 00000000000..3403459f44f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt26-1.fir.kt
@@ -0,0 +1,9 @@
+// FILE: this.kt
+
+// KT-26 Import namespaces defined in this file
+package foo
+
+import bar.* // Must not be an error
+
+// FILE: other.kt
+package bar
diff --git a/compiler/testData/diagnostics/tests/regressions/kt26.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt26.fir.kt
new file mode 100644
index 00000000000..c1557c3de55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt26.fir.kt
@@ -0,0 +1,12 @@
+// FILE: a.kt
+// KT-26 Import namespaces defined in this file
+
+import html.* // Must not be an error
+
+// FILE: b.kt
+
+package html
+
+abstract class Factory<T: Any> {
+fun create() : T? = null
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt26303.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt26303.fir.kt
new file mode 100644
index 00000000000..99e58c6e68a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt26303.fir.kt
@@ -0,0 +1,17 @@
+// FILE: a.kt
+
+package foo
+
+operator fun Int.invoke() = null
+fun Int.foo() = null
+
+// FILE: b.kt
+
+package bar
+
+import foo.foo as invoke
+import foo.invoke
+
+fun main(args: Array<String>) {
+    <!AMBIGUITY!>42()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt2768.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt2768.fir.kt
new file mode 100644
index 00000000000..0670f633eb2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt2768.fir.kt
@@ -0,0 +1,20 @@
+fun <T> assertEquals(a: T, b: T) {
+    if (a != b) throw AssertionError("$a != $b")
+}
+
+fun main() {
+    val bytePos = 128.toByte() // Byte.MAX_VALUE + 1
+    assertEquals(-128, bytePos.toInt()) // correct, wrapped to Byte.MIN_VALUE
+
+    val byteNeg: Byte = -bytePos // should not compile, byteNeg should be Int
+    assertEquals(128, byteNeg.toInt()) // passes, should not be possible
+
+    val shortPos = 32768.toShort() // Short.MAX_VALUE + 1
+    assertEquals(-32768, shortPos.toInt()) // correct, wrapped to Short.MIN_VALUE
+
+    val shortNeg: Short = -shortPos // should not compile, shortNeg should be Int
+    assertEquals(32768, shortNeg.toInt()) // passes, should not be possible
+
+    (-128).toByte()
+    -128.toByte()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt28001.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt28001.fir.kt
new file mode 100644
index 00000000000..0f51ff2f666
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt28001.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+private object Case1 {
+    interface Validator<in T>
+
+    class CharSequenceValidator: Validator<CharSequence>
+
+    class PredicateValidator<T>(val predicate: (T) -> Boolean): Validator<T>
+
+    class CompositeValidator<T>(vararg val validators: Validator<T>)
+
+    fun process(input: String) = true
+
+    fun main() {
+        val validators1 = CompositeValidator(CharSequenceValidator(), PredicateValidator(::process))
+        val validators2 = CompositeValidator<String>(CharSequenceValidator(), PredicateValidator(::process))
+        val validators3 = CompositeValidator(CharSequenceValidator(), PredicateValidator { it: String -> process(it) })
+    }
+}
+
+private object Case2 {
+    interface Expr<out T>
+    data class Add(val left: Expr<Int>, val right: Expr<Int>): Expr<Int>
+    data class Subtract(val left: Expr<Int>, val right: Expr<Int>): Expr<Int>
+
+    fun f() {
+        val operators1 = listOf(::Add, ::Subtract)
+        val operators2 = listOf<(Expr<Int>, Expr<Int>) -> Expr<Int>>(::Add, ::Subtract)
+    }
+
+    fun <T> listOf(vararg elements: T): List<T> = TODO()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt282.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt282.fir.kt
new file mode 100644
index 00000000000..566da395178
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt282.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// KT-282 Nullability in extension functions and in binary calls
+
+class Set {
+    operator fun contains(x : Int) : Boolean = true
+}
+
+operator fun Set?.plus(x : Int) : Int = 1
+
+operator fun Int?.contains(x : Int) : Boolean = false
+
+fun f(): Unit {
+    var set : Set? = null
+    val i : Int? = null
+    i <!INAPPLICABLE_CANDIDATE!>+<!> 1
+    set + 1
+    1 <!INAPPLICABLE_CANDIDATE!>in<!> set
+    1 in 2
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt287.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt287.fir.kt
new file mode 100644
index 00000000000..72ea707f966
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt287.fir.kt
@@ -0,0 +1,12 @@
+// KT-287 Infer constructor type arguments
+
+import java.util.*
+
+fun attributes() : Map<String, String> = HashMap() // Should be inferred;
+val attributes : Map<String, String> = HashMap() // Should be inferred;
+
+fun foo(m : Map<String, String>) {}
+
+fun test() {
+    foo(HashMap())
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt2956.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt2956.fir.kt
new file mode 100644
index 00000000000..491dea82e02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt2956.fir.kt
@@ -0,0 +1 @@
+val a: String = Nothing
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt302.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt302.fir.kt
new file mode 100644
index 00000000000..b13c4b483a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt302.fir.kt
@@ -0,0 +1,13 @@
+// KT-302 Report an error when inheriting many implementations of the same member
+
+package kt302
+
+interface A {
+    open fun foo() {}
+}
+
+interface B {
+    open fun foo() {}
+}
+
+class C : A, B {} //should be error here
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt306.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt306.fir.kt
new file mode 100644
index 00000000000..73c9a1dac4d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt306.fir.kt
@@ -0,0 +1,23 @@
+// KT-306 Ambiguity when different this's have same-looking functions
+
+fun test() {
+    (fun Foo.() {
+        <!UNRESOLVED_REFERENCE!>bar<!>()
+        (fun Barr.() {
+            this.<!UNRESOLVED_REFERENCE!>bar<!>()
+            <!UNRESOLVED_REFERENCE!>bar<!>()
+        })
+    })
+    (fun Barr.() {
+        this.<!UNRESOLVED_REFERENCE!>bar<!>()
+        <!UNRESOLVED_REFERENCE!>bar<!>()
+    })
+}
+
+class Foo {
+    fun bar() {}
+}
+
+class Barr {
+    fun bar() {}
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt307.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt307.fir.kt
new file mode 100644
index 00000000000..67c56729183
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt307.fir.kt
@@ -0,0 +1,11 @@
+// KT-307 Unresolved reference
+
+open class AL {
+    fun get(i : Int) : Any? = i
+}
+
+interface ALE<T> : AL {
+    fun getOrNull(index: Int, value: T) : T {
+        return get(index) as? T ?: value
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt312.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt312.fir.kt
new file mode 100644
index 00000000000..be907b58530
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt312.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// KT-312 Nullability problem when a nullable version of a generic type is returned
+
+fun <T> Array<out T>.safeGet(index : Int) : T? {
+    return if (index < size) this[index] else null
+}
+
+val args : Array<String> = Array<String>(1, {""})
+val name : String = args.safeGet<String>(0) // No error, must be type mismatch
+val name1 : String? = args.safeGet(0)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt313.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt313.fir.kt
new file mode 100644
index 00000000000..d22f0dc4f2e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt313.fir.kt
@@ -0,0 +1,11 @@
+// KT-313 Bug in substitutions in a function returning its type parameter T
+
+fun <T> Iterable<T>.join(separator : String?) : String {
+    return separator.npe()
+}
+
+fun <T : Any> T?.npe() : T {
+    if (this == null)
+      throw NullPointerException()
+    return this;
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt316.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt316.fir.kt
new file mode 100644
index 00000000000..4816e9763f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt316.fir.kt
@@ -0,0 +1,10 @@
+// KT-316 Members of traits must be open by default
+
+interface B {
+    fun bar() {}
+    fun foo() {}
+}
+
+open class A() : B{
+    override fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt31975.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt31975.fir.kt
new file mode 100644
index 00000000000..d7ac5e67b92
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt31975.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface MemoizedFunctionToNotNull<K, V>
+
+fun <K, V : Any> createMemoizedFunction(compute: (K) -> V): MemoizedFunctionToNotNull<K, V> = TODO()
+
+interface A
+
+interface TypeConstructor
+
+class Refiner {
+    val memoizedFunctionLambda = createMemoizedFunction { it.<!INAPPLICABLE_CANDIDATE!>foo<!>() } // error type infered, no diagnostic, BAD, backend fails
+    val memoizedFunctionReference = createMemoizedFunction(TypeConstructor::foo) // EXTENSION_IN_CLASS_REFERENCE_IS_NOT_ALLOWED, fine
+    val memoizedFunctionTypes = createMemoizedFunction<TypeConstructor, Boolean> { it.foo() } // works fine
+
+    private fun TypeConstructor.foo(): Boolean = true
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt32205.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt32205.fir.kt
new file mode 100644
index 00000000000..b8b6498cc7a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt32205.fir.kt
@@ -0,0 +1,12 @@
+// FILE: A.java
+
+public class A {
+    public static void foo(A... values) {}
+}
+
+// FILE: test.kt
+
+fun test(vararg values: A) {
+    A.foo(*values)
+    A.<!INAPPLICABLE_CANDIDATE!>foo<!>(values)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt328.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt328.fir.kt
new file mode 100644
index 00000000000..64d3028683f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt328.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+//KT-328 Local function in function literals cause exceptions
+
+fun bar1() = {
+    bar1()
+}
+
+fun bar2() = {
+    fun foo2() = bar2()
+}
+
+//properties
+//in a class
+class A() {
+    val x = { x }
+}
+
+//in a package
+val x = { x }
+
+//KT-787 AssertionError on code 'val x = x'
+val z = z
+
+//KT-329 Assertion failure on local function
+fun block(f : () -> Unit) = f()
+
+fun bar3() = block{ <!UNRESOLVED_REFERENCE!>foo3<!>() // <-- missing closing curly bracket
+fun foo3() = block{ bar3() }<!SYNTAX!><!>
+
diff --git a/compiler/testData/diagnostics/tests/regressions/kt32836.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt32836.fir.kt
new file mode 100644
index 00000000000..adbdda52fea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt32836.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun <reified T> parse(json: String): T? = TODO()
+
+class MyType
+
+fun parseMyData(json: String): MyType =
+    try {
+        parse(json) // error with new inf only: Cannot use 'Nothing?' as reified type parameter
+            ?: throw IllegalArgumentException("Can't parse")
+    } catch (e: Exception) {
+        throw IllegalArgumentException("Can't parse")
+    }
+
+fun main() {
+    parseMyData("")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt334.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt334.fir.kt
new file mode 100644
index 00000000000..3daf03e8233
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt334.fir.kt
@@ -0,0 +1,8 @@
+// !CHECK_TYPE
+
+import java.lang.Comparable as Comparable
+
+fun f(c: Comparable<*>) {
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><kotlin.Comparable<*>>(c)
+    checkSubtype<java.lang.Comparable<*>>(c)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt335.336.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt335.336.fir.kt
new file mode 100644
index 00000000000..cf1e1ca7fe7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt335.336.fir.kt
@@ -0,0 +1,13 @@
+// KT-336 Can't infer type parameter for ArrayList in a generic function (Exception in type inference)
+// KT-335 Type inference fails on Collections.sort
+
+import java.util.*
+
+fun <T : Comparable<T>> MutableList<T>.sort() {
+  Collections.sort(this) // Error here
+}
+
+fun <T> List<T>.plus(other : List<T>) : List<T> {
+  val result = ArrayList(this)
+  return result
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt337.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt337.fir.kt
new file mode 100644
index 00000000000..7cac265e866
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt337.fir.kt
@@ -0,0 +1,14 @@
+//KT-337 Can't break a line before a dot
+
+class A() {
+    fun foo() {}
+}
+
+fun test() {
+    val a = A()
+
+    a
+
+      .foo() // Should be a valid expression
+
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt352.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt352.fir.kt
new file mode 100644
index 00000000000..ba34d4d076c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt352.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+//KT-352 Function variable declaration type isn't checked inside a function body
+
+package kt352
+
+val f : (Any) -> Unit = {  -> }  //type mismatch
+
+fun foo() {
+    val f : (Any) -> Unit = { -> }  //!!! no error
+}
+
+class A() {
+    val f : (Any) -> Unit = { -> }  //type mismatch
+}
+
+//more tests
+val g : () -> Unit = { 42 }
+val gFunction : () -> Unit = fun(): Int = 1
+
+val h : () -> Unit = { doSmth() }
+
+fun doSmth(): Int = 42
+fun doSmth(a: String) {}
+
+val testIt : (Any) -> Unit = {
+    if (it is String) {
+        doSmth(it)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt353.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt353.fir.kt
new file mode 100644
index 00000000000..86054faac9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt353.fir.kt
@@ -0,0 +1,33 @@
+// !WITH_NEW_INFERENCE
+// KT-353 Generic type argument inference sometimes doesn't work
+
+interface A {
+    fun <T> gen() : T
+}
+
+fun foo(a: A) {
+    val g : () -> Unit = {
+        a.gen()  //it works: Unit is derived
+    }
+
+    val u: Unit = a.gen() // Unit should be inferred
+
+    if (true) {
+        a.gen() // Shouldn't work: no info for inference
+    }
+
+    val b : () -> Unit = {
+        if (true) {
+            a.gen()  // unit can be inferred
+        }
+        else {
+            Unit
+        }
+    }
+
+    val f : () -> Int = {
+        a.gen()  //type mismatch, but Int can be derived
+    }
+
+    a.gen() // Shouldn't work: no info for inference
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt3535.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt3535.fir.kt
new file mode 100644
index 00000000000..4b027cb07d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt3535.fir.kt
@@ -0,0 +1,9 @@
+// KT-3535 Functional value-parametr in nested class is inaccessible
+
+class Foo {
+    class Bar(val p: (Any) -> Any) {
+        fun f() {
+            p(1)
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt3647.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt3647.fir.kt
new file mode 100644
index 00000000000..75416a55034
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt3647.fir.kt
@@ -0,0 +1,9 @@
+// KT-3647 Unexpected compilation error: "Expression is inaccessible from a nested class"
+
+class Test(val value: Int) {
+    companion object {
+        fun create(init: () -> Int): Test {
+            return Test(init())
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt3731.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt3731.fir.kt
new file mode 100644
index 00000000000..c68937faed5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt3731.fir.kt
@@ -0,0 +1,17 @@
+// KT-3731 Resolve & inner class
+
+class A {
+    fun foo() {}
+    fun bar(f: A.() -> Unit = {}) = <!INAPPLICABLE_CANDIDATE!>f<!>()
+}
+
+class B {
+    class D {
+        init {
+            A().bar {
+                this.<!UNRESOLVED_REFERENCE!>foo<!>()
+                <!UNRESOLVED_REFERENCE!>foo<!>()
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt3810.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt3810.fir.kt
new file mode 100644
index 00000000000..a9b163040e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt3810.fir.kt
@@ -0,0 +1,5 @@
+interface A {
+    var foo: String
+}
+
+class B(override val foo: String) : A
diff --git a/compiler/testData/diagnostics/tests/regressions/kt385.109.441.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt385.109.441.fir.kt
new file mode 100644
index 00000000000..625e715e707
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt385.109.441.fir.kt
@@ -0,0 +1,33 @@
+// KT-385 type inference does not work properly`
+// KT-109 Good code is red: type arguments are not inferred
+// KT-441 Exception in type inference when multiple overloads accepting an integer literal are accessible
+
+import java.util.*
+
+infix fun <T> Iterator<T>.foreach(operation: (element: T) -> Unit)  : Unit { while(hasNext()) operation(next()) }
+
+infix fun <T> Iterator<T>.foreach(operation: (index: Int, element: T) -> Unit) : Unit {
+    var k = 0
+    while(hasNext())
+        operation(k++, next())
+}
+
+fun <T> Iterable<T>.foreach(operation: (element: T) -> Unit) : Unit = iterator() foreach operation
+
+fun <T> Iterable<T>.foreach(operation: (index: Int, element: T) -> Unit) : Unit = iterator() foreach operation
+
+fun box() : String {
+    return generic_invoker( { "OK"} )
+}
+
+fun <T> generic_invoker(gen :  () -> T) : T {
+    return gen()
+}
+
+fun println(message : Int) { System.out.println(message) }
+fun println(message : Long) { System.out.println(message) }
+
+fun main() {
+
+    println(run { 1 })
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt394.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt394.fir.kt
new file mode 100644
index 00000000000..53a666fc641
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt394.fir.kt
@@ -0,0 +1,11 @@
+// KT-394 Make companion object members visible inside the owning class
+
+class X() {
+//    class Y {}
+
+    companion object{
+        class Y() {}
+    }
+
+    val y : Y = Y()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt398.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt398.fir.kt
new file mode 100644
index 00000000000..4302b861f9a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt398.fir.kt
@@ -0,0 +1,11 @@
+// KT-398 Internal error when property initializes with function
+
+class X<T>() {
+    val check = { a : Any -> a is T }
+}
+
+fun box() : String {
+    if(X<String>().check(10)) return "fail"
+    if(!X<String>().check("lala")) return "fail"
+    return "OK"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt399.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt399.fir.kt
new file mode 100644
index 00000000000..0fc1d91fffc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt399.fir.kt
@@ -0,0 +1,11 @@
+// KT-399 Type argument inference not implemented for CALL_EXPRESSION
+
+fun <T> getSameTypeChecker(obj: T) : Function1<Any,Boolean> {
+    return { a : Any -> a is T }
+}
+
+fun box() : String {
+    if(getSameTypeChecker<String>("lala")(10)) return "fail"
+    if(!getSameTypeChecker<String>("mama")("lala")) return "fail"
+    return "OK"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt402.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt402.fir.kt
new file mode 100644
index 00000000000..9594f32f227
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt402.fir.kt
@@ -0,0 +1,8 @@
+package kt402
+
+fun getTypeChecker() : (Any)->Boolean {
+  { a : Any -> a is T } // reports unsupported
+}
+fun f() : (Any) -> Boolean {
+  return { a : Any -> a is String }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt41.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt41.fir.kt
new file mode 100644
index 00000000000..086d22787c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt41.fir.kt
@@ -0,0 +1,11 @@
+// KT-41 Make functions with errors in returning statement return ERROR type and not Nothing
+
+package kt41
+
+fun aaa() =
+  6 <!UNRESOLVED_REFERENCE!>foo<!> 1
+
+fun bbb() {
+  aaa()
+  1 // Stupid error: unreachable code
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt411.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt411.fir.kt
new file mode 100644
index 00000000000..e5b9998793d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt411.fir.kt
@@ -0,0 +1,69 @@
+//kt-411 Wrong type expected when returning from a function literal
+
+package kt411
+
+fun f() {
+    invoker(
+    l@{
+        return@l 11 // expects Function, but should expect Int
+    }
+    )
+}
+fun invoker(gen : () -> Int) : Int  = 0
+
+//more tests
+fun t1() {
+    val v = l@{
+        return@l 111
+    }
+}
+
+fun t2() : String {
+    val g : ()-> Int = l@{
+        if (true) {
+            return@l 1
+        }
+        return "s"
+    }
+    return "s"
+}
+
+fun t3() : String {
+    invoker(
+    l@{
+        if (true) {
+            return@t3 "1"
+        }
+        else {
+            return 2
+        }
+        return@l 0
+    }
+    )
+    invoker(
+    l@{
+        return@l 1
+    }
+    )
+    invoker(
+    {
+        return "0"
+    }
+    )
+    return "2"
+}
+
+fun t4() : Int {
+    val h :  ()-> String = l@{
+        return@l "a"
+    }
+    val g :  ()-> String = l@{
+        return@l "a"
+    }
+
+    fun inner(): String {
+        return "2"
+    }
+
+    return 12
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt439.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt439.fir.kt
new file mode 100644
index 00000000000..d55d6a501f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt439.fir.kt
@@ -0,0 +1,5 @@
+// KT-439 Support labeled function literals in call arguments
+
+fun main1(args : Array<String>) {
+    run l@{ 1 } // should not be an error
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt442.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt442.fir.kt
new file mode 100644
index 00000000000..806772e9518
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt442.fir.kt
@@ -0,0 +1,31 @@
+// KT-442 Type inference fails on with()
+
+fun <T> funny(f : () -> T) : T = f()
+
+fun testFunny() {
+    val a : Int = funny {1}
+}
+
+fun <T> funny2(f : (t : T) -> T) : T {}
+
+fun testFunny2() {
+    val a : Int = funny2 {it}
+}
+
+fun box() : String {
+    return generic_invoker { it }
+}
+
+fun <T> generic_invoker(gen :  (String) -> T) : T {
+    return gen("")
+}
+
+infix fun <T> T.with(f :  T.() -> Unit) {
+    <!INAPPLICABLE_CANDIDATE!>f<!>()
+}
+
+fun main() {
+    val a = 1 with {
+        <!UNRESOLVED_REFERENCE!>plus<!>(1)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt443.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt443.fir.kt
new file mode 100644
index 00000000000..c2a6e972395
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt443.fir.kt
@@ -0,0 +1,14 @@
+// KT-443 Write allowed to super.val
+
+open class M() {
+    open val b: Int = 5
+}
+
+class N() : M() {
+    val a : Int
+        get() {
+            super.b = super.b + 1
+            return super.b + 1
+        }
+    override val b: Int = a + 1
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt455.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt455.fir.kt
new file mode 100644
index 00000000000..fb57b0d1f06
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt455.fir.kt
@@ -0,0 +1,10 @@
+//KT-455 Do not repeat errors in definite assignment checks
+
+package kt455
+
+fun foo() {
+    val a: Int
+    doSmth(a)   //error
+    doSmth(a)   //no repeat error
+}
+fun doSmth(i: Int) {}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt456.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt456.fir.kt
new file mode 100644
index 00000000000..a26799fc949
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt456.fir.kt
@@ -0,0 +1,30 @@
+//KT-456 No check for obligatory return in getters
+
+package kt456
+
+class A() {
+    val i: Int
+    get() : Int {  //no error
+    }
+}
+
+//more tests
+class B() {
+    val i: Int
+    get() {  //no error
+    }
+}
+
+class C() {
+    val i : Int
+    get() : Int {
+        try {
+            doSmth()
+        }
+        finally {
+            doSmth()
+        }
+    }
+}
+
+fun doSmth() {}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt459.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt459.fir.kt
new file mode 100644
index 00000000000..02c5f40b7d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt459.fir.kt
@@ -0,0 +1,8 @@
+// KT-459 Type argument inference fails when class names are fully qualified
+
+fun test() {
+  val attributes : java.util.HashMap<String, String> = java.util.<!UNRESOLVED_REFERENCE!>HashMap<!>() // failure!
+  attributes["href"] = "1" // inference fails, but it shouldn't
+}
+
+operator fun <K, V> Map<K, V>.set(key : K, value : V) {}//= this.put(key, value)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt469.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt469.fir.kt
new file mode 100644
index 00000000000..716cda78433
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt469.fir.kt
@@ -0,0 +1,28 @@
+
+package kt469
+
+//KT-512 plusAssign() : Unit does not work properly
+import java.util.*
+
+fun bar(list : MutableList<Int>) {
+    for (i in 1..10) {
+        list += i // error
+    }
+    System.out.println(list)
+}
+
+operator fun <T> MutableList<T>.plusAssign(t : T) {
+    add(t)
+}
+
+//KT-469 Allow val-reassignment when appropriate functions are defined
+fun foo() {
+    val m = MyNumber(2)
+    m -= MyNumber(3)           //should not be error here
+}
+
+class MyNumber(var i: Int) {
+    operator fun minusAssign(m : MyNumber) {
+        i -= m.i
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt4693.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt4693.fir.kt
new file mode 100644
index 00000000000..a0b38e239f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt4693.fir.kt
@@ -0,0 +1,8 @@
+enum class MyEnum {
+    K;
+    
+    inline fun doSmth(f: (MyEnum) -> String) : String {
+        // This function should be inline
+        return f(K)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt4827.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt4827.fir.kt
new file mode 100644
index 00000000000..423a1c27326
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt4827.fir.kt
@@ -0,0 +1,16 @@
+// KT-4827 UOE at PackageType.throwException()
+// EA-53605
+
+public interface TestInterface {
+}
+
+class C {
+    inner class I {
+
+    }
+}
+
+fun f() {
+    <!UNRESOLVED_REFERENCE!>TestInterface<!>()
+    C.<!UNRESOLVED_REFERENCE!>I<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt498.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt498.fir.kt
new file mode 100644
index 00000000000..057b3aaf57e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt498.fir.kt
@@ -0,0 +1,8 @@
+// JAVAC_EXPECTED_FILE
+// KT-498 Very strange error in the type checker
+
+class IdUnavailableException() : Exception() {}
+
+fun <T : Any> T.getJavaClass() : Class<T> {
+    return ((this as Object).getClass()) as Class<T> // Some error here, because of Exception() used above. ?!!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt524.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt524.fir.kt
new file mode 100644
index 00000000000..f69e5d58442
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt524.fir.kt
@@ -0,0 +1,14 @@
+// KT-524 sure() returns T
+
+package StringBuilder
+
+//import kotlin.io.*
+//import java.io.*
+
+fun main() {
+}
+
+val Int.bd : StringBuilder get() = StringBuilder(this.toString())
+fun StringBuilder.plus(other : StringBuilder) : StringBuilder = this.append(other).sure1() // !!!
+
+fun <T : Any> T?.sure1() : T { return if (this != null) this else throw NullPointerException() }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt526UnresolvedReferenceInnerStatic.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt526UnresolvedReferenceInnerStatic.fir.kt
new file mode 100644
index 00000000000..ceaf5571d30
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt526UnresolvedReferenceInnerStatic.fir.kt
@@ -0,0 +1,15 @@
+// http://youtrack.jetbrains.net/issue/KT-526
+// KT-526 Unresolved reference for inner static class
+
+package demo
+
+class Foo {
+    companion object {
+        class Bar() { }
+    }
+}
+class User {
+    fun main() : Unit {
+        var boo : Foo.Companion.Bar? /* <-- this reference is red */ = Foo.Companion.Bar()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt5326.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt5326.fir.kt
new file mode 100644
index 00000000000..e788a418d21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt5326.fir.kt
@@ -0,0 +1,11 @@
+class A<T> {
+    fun size() = 0
+}
+
+class Foo<T>(i: Int)
+
+public fun <E> Foo(c: A<E>) {
+    val a = Foo<E>(c.size())       // Check no overload resolution ambiguity
+    val b: Foo<E> = Foo(c.size())  // OK
+    val c: Foo<Int> = Foo(c.size()) // OK
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt5362.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt5362.fir.kt
new file mode 100644
index 00000000000..bb381e210a5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt5362.fir.kt
@@ -0,0 +1,31 @@
+// !WITH_NEW_INFERENCE
+// KT-5362 Compiler crashes on access to extension method from nested class
+class Outer {
+    class Nested{
+        fun foo(s: String) = s.<!UNRESOLVED_REFERENCE!>extension<!>()
+    }
+
+    private fun String.extension(): String = this
+}
+
+// EA-64302 - UOE: CodegenContext.getOuterExpression
+fun Activity.toast() = Unit
+class Activity(){
+    class Fragment{
+        fun call() = toast()
+    }
+}
+
+// KT-8814 No error in IDE for invalid invoke of OuterClass.()->Unit in static nested class
+public class Manager {
+    fun task(callback: Manager.() -> Unit): Task {
+        val task = Task(callback)
+        return task
+    }
+
+    class Task(val callback: Manager.() -> Unit) : Runnable {
+        override public fun run() {
+            <!INAPPLICABLE_CANDIDATE!>callback<!>() // Manager is not accessible here, but no error is shown
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt549.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt549.fir.kt
new file mode 100644
index 00000000000..4f1e0359083
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt549.fir.kt
@@ -0,0 +1,17 @@
+//KT-549 type inference failed
+
+package demo
+
+  fun <T> filter(list : Array<T>, filter :  (T) -> Boolean) : List<T> {
+    val answer = java.util.<!UNRESOLVED_REFERENCE!>ArrayList<!><T>();
+    for (l in list) {
+      if (filter(l)) answer.<!UNRESOLVED_REFERENCE!>add<!>(l)
+    }
+    return answer;
+  }
+
+fun main(args : Array<String>) {
+  for (a in filter(args, {it.length > 1})) {
+    System.out.println("Hello, ${a}!")
+  }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt557.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt557.fir.kt
new file mode 100644
index 00000000000..c24e96f737d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt557.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// KT-557 Wrong type inference near sure extension function
+
+fun <T : Any> T?.sure() : T = this!!
+
+fun Array<String>.length() : Int {
+    return 0;
+}
+
+fun test(array : Array<String?>?) {
+    array?.sure<Array<String?>>().<!INAPPLICABLE_CANDIDATE!>length<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt571.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt571.fir.kt
new file mode 100644
index 00000000000..9a6cfce30a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt571.fir.kt
@@ -0,0 +1,3 @@
+//KT-571 Type inference failed
+fun <T, R> let(t : T, body : (T) -> R) = body(t)
+private fun double(d : Int) : Int = let(d * 2) {it / 10 + it * 2 % 10}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt575.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt575.fir.kt
new file mode 100644
index 00000000000..45c9def4f26
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt575.fir.kt
@@ -0,0 +1,32 @@
+// KT-575 Cannot ++ a companion object member
+
+package kt575
+
+class Creature() {
+    companion object {
+        var numCreated : Int = 0
+          private set
+    }
+
+    object A {
+        var bbb : Int
+
+        init {
+            bbb = 1
+        }
+    }
+
+    class C() {
+        var ccc : Int
+
+        init {
+            ccc = 2
+        }
+    }
+
+    init {
+        Creature.numCreated++ // Error
+        A.bbb++
+        C().ccc++
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt58.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt58.fir.kt
new file mode 100644
index 00000000000..6103492c7df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt58.fir.kt
@@ -0,0 +1,91 @@
+//KT-58 Allow finally around definite returns
+
+package kt58
+
+import java.util.concurrent.locks.Lock
+
+fun <T> lock(lock : Lock, body :  () -> T) : T {
+    lock.lock()
+    try {
+        return body()
+    }
+    finally {
+        lock.unlock(); // we report an error, but we chouldn't
+    }
+}
+
+//more tests
+fun t1() : Int {
+    try {
+        return 1
+    }
+    finally {
+        return 2
+    }
+}
+
+fun t2() : Int {
+    try {
+        return 1
+    }
+    finally {
+        doSmth(3)
+    }
+}
+
+fun t3() : Int {
+    try {
+        return 1
+    }
+    catch (e: UnsupportedOperationException) {
+        doSmth(2)
+    }
+    finally {
+        doSmth(3)
+    }
+}
+
+fun t4() : Int {
+    try {
+        return 1
+    }
+    catch (e: UnsupportedOperationException) {
+        doSmth(2)
+    }
+}
+
+fun t5() : Int {
+    try {
+        return 1
+    }
+    catch (e: UnsupportedOperationException) {
+        return 2
+    }
+}
+
+fun t6() : Int {
+    try {
+        return 1
+    }
+    catch (e: UnsupportedOperationException) {
+        return 2
+    }
+    finally {
+        doSmth(3)
+    }
+}
+
+fun t7() : Int {
+    try {
+        doSmth(1)
+    }
+    catch (e: UnsupportedOperationException) {
+        return 2
+    }
+    finally {
+        doSmth(3)
+    }
+}
+
+fun doSmth(i: Int) {
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt580.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt580.fir.kt
new file mode 100644
index 00000000000..c85036ad700
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt580.fir.kt
@@ -0,0 +1,22 @@
+//KT-580 Type inference failed
+
+package whats.the.difference
+
+import java.util.*
+
+fun iarray(vararg a : String) = a // BUG
+
+fun main() {
+    val vals = iarray("789", "678", "567")
+    val diffs = ArrayList<Int>()
+    for (i in vals.indices) {
+        for (j in i..vals.lastIndex())  // Type inference failed
+             diffs.add(vals[i].length - vals[j].length)
+        for (j in i..vals.lastIndex)  // Type inference failed
+             diffs.add(vals[i].length - vals[j].length)
+    }
+}
+
+fun <T> Array<T>.lastIndex() = size - 1
+val <T> Array<T>.lastIndex : Int get() = size - 1
+val <T> Array<T>.indices : IntRange get() = IntRange(0, lastIndex)
diff --git a/compiler/testData/diagnostics/tests/regressions/kt588.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt588.fir.kt
new file mode 100644
index 00000000000..4f6637a9eb5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt588.fir.kt
@@ -0,0 +1,14 @@
+// JAVAC_EXPECTED_FILE
+// KT-588 Unresolved static method
+
+class Test() : Thread("Test") {
+    companion object {
+        fun init2() {
+
+        }
+    }
+    override fun run() {
+        init2()      // unresolved
+        Test.init2() // ok
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt597.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt597.fir.kt
new file mode 100644
index 00000000000..2b4251e990d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt597.fir.kt
@@ -0,0 +1,19 @@
+//KT-597 Type inference failed
+
+fun <T> Array<T>?.get(i: Int) : T {
+    if (this != null)
+        return this.get(i) // <- inferred type is Any? but &T was excepted
+    else throw NullPointerException()
+}
+
+operator fun Int?.inc() : Int {
+    if (this != null)
+        return this.inc()
+    else
+        throw NullPointerException()
+}
+
+fun test() {
+   var i : Int? = 10
+   var i_inc = i++ // <- expected Int?, but returns Any?
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt600.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt600.fir.kt
new file mode 100644
index 00000000000..65ed8d40266
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt600.fir.kt
@@ -0,0 +1,8 @@
+//KT-600 Problem with 'sure' extension function type inference
+
+fun <T : Any> T?._sure() : T { if (this != null) return this else throw NullPointerException() }
+
+fun test() {
+    val i : Int? = 10
+    val i2 : Int = i._sure() // inferred type is Int? but Int was excepted
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt604.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt604.fir.kt
new file mode 100644
index 00000000000..43e81d89fde
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt604.fir.kt
@@ -0,0 +1,20 @@
+// KT-604 Internal frontend error
+
+interface ChannelPipeline {
+
+}
+
+class DefaultChannelPipeline() : ChannelPipeline {
+}
+
+interface ChannelPipelineFactory{
+    fun getPipeline() : ChannelPipeline
+}
+
+class StandardPipelineFactory(val config:  ChannelPipeline.()->Unit) : ChannelPipelineFactory {
+    override fun getPipeline() : ChannelPipeline {
+        val pipeline = DefaultChannelPipeline()
+        pipeline.<!UNRESOLVED_REFERENCE!>config<!> ()
+        return pipeline
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt618.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt618.fir.kt
new file mode 100644
index 00000000000..5c823fef416
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt618.fir.kt
@@ -0,0 +1,28 @@
+package lol
+
+class B() {
+    operator fun plusAssign(other : B) : String {
+        return "s"
+    }
+    operator fun minusAssign(other : B) : String {
+        return "s"
+    }
+    operator fun remAssign(other : B) : String {
+        return "s"
+    }
+    operator fun divAssign(other : B) : String {
+        return "s"
+    }
+    operator fun timesAssign(other : B) : String {
+        return "s"
+    }
+}
+
+fun main() {
+    var c = B()
+    c += B()
+    c *= B()
+    c /= B()
+    c -= B()
+    c %= B()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt629.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt629.fir.kt
new file mode 100644
index 00000000000..b4cc8300702
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt629.fir.kt
@@ -0,0 +1,23 @@
+//KT-629 Assignments are parsed as expressions.
+
+package kt629
+
+class A() {
+    var p = "yeah"
+    operator fun rem(other : A) : A {
+        return A();
+    }
+}
+
+fun box() : Boolean {
+    var c = A()
+    val d = c;
+    c %= A();
+    return (c != d) && <!INFERENCE_ERROR!>(c.p = "yeah")<!>
+}
+
+
+fun box2() : Boolean {
+    var c = A()
+    return <!INFERENCE_ERROR!>(c.p = "yeah")<!> && true
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt630.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt630.fir.kt
new file mode 100644
index 00000000000..2cef7f519a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt630.fir.kt
@@ -0,0 +1,6 @@
+// KT-630 Bad type inference
+
+fun <T : Any> T?.sure() : T = this!!
+
+val x = "lala".sure()
+val s : String = x
diff --git a/compiler/testData/diagnostics/tests/regressions/kt6508.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt6508.fir.kt
new file mode 100644
index 00000000000..059496b69ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt6508.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+// FILE: foo/View.java
+
+package foo;
+
+public class View {}
+
+// FILE: foo/TextView.java
+
+package foo;
+
+public class TextView extends View {}
+
+// FILE: k.kt
+
+import foo.View
+//import foo.TextView
+
+fun String.gah(view:View ?) {
+    if (view is TextView)
+        view
+    else <!UNRESOLVED_REFERENCE!>TextView<!>() as foo.TextView
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt688.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt688.fir.kt
new file mode 100644
index 00000000000..b29056972ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt688.fir.kt
@@ -0,0 +1,14 @@
+// KT-668 Failed to resolve generic parameter
+open class A()
+open class B() : A() {
+  fun b(): B = B()
+}
+
+
+class C() {
+  fun <T> a(x: (T)->T, y: T): T {
+    return x(x(y))
+  }
+
+  val x: B = a({it.b()}, B())
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt691.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt691.fir.kt
new file mode 100644
index 00000000000..ae9df808ea1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt691.fir.kt
@@ -0,0 +1,2 @@
+// KT-691 Allow to create nested namespaces with dot delimiter
+package foo.bar.buz
diff --git a/compiler/testData/diagnostics/tests/regressions/kt701.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt701.fir.kt
new file mode 100644
index 00000000000..509e0f33460
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt701.fir.kt
@@ -0,0 +1,17 @@
+// KT-702 Type inference failed
+fun <T> getJavaClass() : java.lang.Class<T> { return "" as Class<T> }
+
+public class Throwables() {
+    companion object {
+        public fun <X : Throwable?> propagateIfInstanceOf(throwable : Throwable?, declaredType : Class<X?>?) {
+            if (((throwable != null) && declaredType?.isInstance(throwable)!!))
+            {
+                throw declaredType?.cast(throwable)!!
+            }
+        }
+        public fun propagateIfPossible(throwable : Throwable?) {
+            <!INAPPLICABLE_CANDIDATE!>propagateIfInstanceOf<!>(throwable, getJavaClass<Error?>()) //; Type inference failed: Mismatch while expanding constraints
+            <!INAPPLICABLE_CANDIDATE!>propagateIfInstanceOf<!>(throwable, getJavaClass<RuntimeException?>()) // Type inference failed: Mismatch while expanding constraints
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt716.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt716.fir.kt
new file mode 100644
index 00000000000..86e1944ff77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt716.fir.kt
@@ -0,0 +1,16 @@
+// KT-716 Type inference failed
+
+class TypeInfo<T>
+
+fun <T> typeinfo() : TypeInfo<T> = null as TypeInfo<T>
+
+fun <T> TypeInfo<T>.getJavaClass() : java.lang.Class<T> {
+    val t : java.lang.Object = this as java.lang.Object
+    return t.getClass() as java.lang.Class<T> // inferred type is Object but Serializable was expected
+}
+
+fun <T> getJavaClass() = typeinfo<T>().getJavaClass()
+
+fun main() {
+    System.out.println(getJavaClass<String>())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt743.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt743.fir.kt
new file mode 100644
index 00000000000..aec66570b8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt743.fir.kt
@@ -0,0 +1,7 @@
+//KT-743 Wrong type inference
+class List<T>(val head: T, val tail: List<T>? = null)
+
+fun <T : Any> T?.sure() : T = this!!
+
+fun <T, Q> List<T>.map(f: (T)-> Q): List<T>? = tail.sure<List<T>>().map(f)
+fun <T> foo(t : T) : T = foo(t)
diff --git a/compiler/testData/diagnostics/tests/regressions/kt750.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt750.fir.kt
new file mode 100644
index 00000000000..8fc9cf40d2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt750.fir.kt
@@ -0,0 +1,10 @@
+//KT-750 Type inference failed: Constraint violation
+fun main() {
+  var i : Int? = Integer.valueOf(100)
+  var s : Int? = Integer.valueOf(100)
+
+  val o = i.sure() + s.sure()
+  System.out.println(o)
+}
+
+fun <T : Any> T?.sure() : T = this!!
diff --git a/compiler/testData/diagnostics/tests/regressions/kt7585/base.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt7585/base.fir.kt
new file mode 100644
index 00000000000..f0170d5a349
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt7585/base.fir.kt
@@ -0,0 +1,20 @@
+open class A
+
+class E
+
+abstract class Wrapper<T: A>(protected val t: T)
+
+class MyWrapper(a: A): Wrapper<A>(a)
+
+// This wrapper is not legal
+class TheirWrapper(e: E): <!INAPPLICABLE_CANDIDATE!>Wrapper<E><!>(e)
+
+data class Pair<out T>(val a: T, val b: T)
+
+fun foo(): String {
+    val matrix: Pair<Wrapper<*>>
+    // It's not legal to do such a thing because E is not derived from A
+    // But we should not have assertion errors because of it!
+    matrix = Pair(MyWrapper(A()), TheirWrapper(E()))
+    return matrix.toString()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt7585/java.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt7585/java.fir.kt
new file mode 100644
index 00000000000..c73bcd67b3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt7585/java.fir.kt
@@ -0,0 +1,30 @@
+// FILE: A.java
+
+public class A {}
+
+// FILE: Wrapper.java
+
+public abstract class Wrapper<T extends A> {
+    protected T t;
+
+    Wrapper(T t) { this.t = t; }
+}
+
+// FILE: kt7585.kt
+
+class E
+
+class MyWrapper(a: A): Wrapper<A>(a)
+
+// This wrapper is not legal
+class TheirWrapper(e: E): <!INAPPLICABLE_CANDIDATE!>Wrapper<E><!>(e)
+
+data class Pair<out T>(val a: T, val b: T)
+
+fun foo(): String {
+    val matrix: Pair<Wrapper<*>>
+    // It's not legal to do such a thing because E is not derived from A
+    // But we should not have assertion errors because of it!
+    matrix = Pair(MyWrapper(A()), TheirWrapper(E()))
+    return matrix.toString()
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt7585/twoparents.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt7585/twoparents.fir.kt
new file mode 100644
index 00000000000..9c328541484
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt7585/twoparents.fir.kt
@@ -0,0 +1,16 @@
+interface X {
+    fun foo(): Int = 42
+}
+
+interface Y
+
+class A: X, Y
+
+class B: X, Y
+
+class Out<out T: X>(val x: T)
+
+fun bar(a: Out<A>, b: Out<B>, f: Boolean): Int {
+    val x = if (f) a else b
+    return x.x.foo()    
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt762.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt762.fir.kt
new file mode 100644
index 00000000000..8409b20d947
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt762.fir.kt
@@ -0,0 +1,4 @@
+//KT-762 Wrong highlighting in imports (No errors reported on unresolved imports)
+import aaa // must be an error
+
+fun main() {}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt7804.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt7804.fir.kt
new file mode 100644
index 00000000000..c03b3af14a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt7804.fir.kt
@@ -0,0 +1,65 @@
+// !WITH_NEW_INFERENCE
+// See also KT-7804 (Wrong type inference of kotlin.Any? was for 'a' without explicit type)
+fun <T> foo(a: T) = a
+
+class A
+
+fun <T> test(v: T): T {
+    val a = if (v !is A) {
+        foo(v) as T
+    }
+    else {
+        v
+    }
+
+    val t: T = a
+    return t
+}
+
+fun <T> test2(v: T): T {
+    val a = if (v !is A) {
+        foo(v) as T
+    }
+    else {
+        v as T
+    }
+
+    val t: T = a
+    return t
+}
+
+fun <T> test3(v: T): T {
+    val a = if (v !is A) {
+        foo(v)
+    }
+    else {
+        v
+    }
+
+    val t: T = a
+    return t
+}
+
+fun <T> test4(v: T): T {
+    val a: T = if (v !is A) {
+        foo(v) as T
+    }
+    else {
+        v
+    }
+
+    val t: T = a
+    return t
+}
+
+fun <T> test5(v: T): T {
+    val a: T = if (v !is A) {
+        foo(v)
+    }
+    else {
+        v
+    }
+
+    val t: T = a
+    return t
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt847.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt847.fir.kt
new file mode 100644
index 00000000000..0f9ecd9fca0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt847.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+fun <T> T.mustBe(t : T) {
+    "$this must be$<!SYNTAX!>as<!>$t"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt860.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt860.fir.kt
new file mode 100644
index 00000000000..bcd42bc7ca5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt860.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+// KT-860 ConcurrentModificationException in frontend
+
+package std.util
+
+import java.util.*
+
+fun <T, U: MutableCollection<in T>> Iterator<T>.to(container: U) : U {
+    while(hasNext())
+        container.add(next())
+    return container
+}
+
+fun <T> Iterator<T>.toArrayList() = to(ArrayList<T>())
diff --git a/compiler/testData/diagnostics/tests/regressions/kt9384.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt9384.fir.kt
new file mode 100644
index 00000000000..e635089121b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt9384.fir.kt
@@ -0,0 +1,11 @@
+fun main(args: Array<String>) {
+    fun f() = run {
+        private class C {
+            private fun foo() {
+                f().<!UNRESOLVED_REFERENCE!>foo<!>();
+
+            }
+        }
+        C()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt9620.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt9620.fir.kt
new file mode 100644
index 00000000000..e5c89b2cf7c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt9620.fir.kt
@@ -0,0 +1,14 @@
+// KT-9620 AssertionError in checkBounds
+
+interface E1<T : D<String>, D>
+
+interface A
+interface B
+interface D<X>
+interface E2<T : D<A>, D<!SYNTAX!><<!><!SYNTAX!>B<!><!SYNTAX!>><!><!SYNTAX!>><!>
+
+// KT-11354 AE from DescriptorResolver
+
+open class L<E>()
+
+class M<C> : L<C<C>>()
diff --git a/compiler/testData/diagnostics/tests/regressions/kt9633.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt9633.fir.kt
new file mode 100644
index 00000000000..21f1bf4be71
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt9633.fir.kt
@@ -0,0 +1,2 @@
+// KT-9633: SOE occurred before
+interface A<T : A<in T>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt9682.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt9682.fir.kt
new file mode 100644
index 00000000000..4c9858a1322
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt9682.fir.kt
@@ -0,0 +1,28 @@
+// KT-9682 Overload Resolution Ambiguity after casting to Interface
+
+open class Foo {
+    fun bar(): Foo {
+        return this
+    }
+}
+
+class Foo2 : Foo(), IFoo
+
+interface IFoo {
+    fun bar(): Foo
+}
+
+fun test() {
+    val foo : Foo = Foo2()
+    foo as IFoo
+    foo.<!AMBIGUITY!>bar<!>() // Should be resolved to Foo#bar
+}
+
+interface IFoo2 {
+    fun bar(): IFoo2
+}
+
+fun test2(foo: Foo) {
+    foo as IFoo2
+    foo.<!AMBIGUITY!>bar<!>() // should be ambiguity
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt9808.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt9808.fir.kt
new file mode 100644
index 00000000000..7d35fb2356f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/kt9808.fir.kt
@@ -0,0 +1,8 @@
+// KT-9808 Extension function on object for new resolve
+object O
+
+val foo: O.() -> Unit  = null!!
+
+fun test() {
+    O.<!UNRESOLVED_REFERENCE!>foo<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/noThis.fir.kt b/compiler/testData/diagnostics/tests/regressions/noThis.fir.kt
new file mode 100644
index 00000000000..71aa9ab8f50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/noThis.fir.kt
@@ -0,0 +1,10 @@
+interface A { fun f() }
+
+open class P(val z: B)
+
+class B : A {
+    override fun f() {}
+    class C : A by this {}
+    class D(val x : B = this)
+    class E : <!INAPPLICABLE_CANDIDATE!>P<!>(this)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/propertyWithExtensionTypeInvoke.fir.kt b/compiler/testData/diagnostics/tests/regressions/propertyWithExtensionTypeInvoke.fir.kt
new file mode 100644
index 00000000000..c4746cd8f7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/propertyWithExtensionTypeInvoke.fir.kt
@@ -0,0 +1,7 @@
+object X
+
+class Y {
+    fun f(op: X.() -> Unit) {
+        X.<!UNRESOLVED_REFERENCE!>op<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.fir.kt b/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.fir.kt
new file mode 100644
index 00000000000..3864f5105af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.fir.kt
@@ -0,0 +1,7 @@
+import java.util.ArrayList
+
+fun foo(p: java.util.List<String>) {
+    p.iterator(); // forcing resolve of java.util.List.iterator()
+
+    ArrayList<String>().iterator(); // this provoked exception in SignaturesPropagationData
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/CycleInTypeArgs.fir.kt b/compiler/testData/diagnostics/tests/resolve/CycleInTypeArgs.fir.kt
new file mode 100644
index 00000000000..d62d8547efd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/CycleInTypeArgs.fir.kt
@@ -0,0 +1,3 @@
+class Class1<T : Class2<Class1<X>>>
+
+class Class2<T : Class1<Class2<X>>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/HiddenDeclarations.fir.kt b/compiler/testData/diagnostics/tests/resolve/HiddenDeclarations.fir.kt
new file mode 100644
index 00000000000..153352100f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/HiddenDeclarations.fir.kt
@@ -0,0 +1,74 @@
+package test
+
+// imports should be resolved
+import test.topLevelFun
+import test.topLevelProperty
+
+@Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+fun topLevelFun(){}
+
+@Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+var topLevelProperty = 1
+
+@Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+fun String.topLevelExtensionFun(){}
+
+@Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+val String.topLevelExtensionProperty: Int get() = 1
+
+open class A {
+    constructor(p: Int) : this("") {}
+
+    @Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+    constructor(s: String){}
+
+    @Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+    open fun memberFun(){}
+
+    @Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+    val memberProperty = 1
+
+    @Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+    fun String.memberExtensionFun(){}
+
+    @Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+    val String.memberExtensionProperty: Int get() = 1
+
+    fun foo() {
+        topLevelFun()
+        topLevelProperty++
+        "".topLevelExtensionFun()
+        "".topLevelExtensionProperty
+
+        memberFun()
+        memberProperty
+        "".memberExtensionFun()
+        "".memberExtensionProperty
+
+        A("")
+    }
+}
+
+interface I {
+    @Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+    fun foo1()
+
+    @Deprecated("hidden", level = DeprecationLevel.HIDDEN)
+    fun foo2()
+}
+
+class X : I {
+    override fun foo1() {
+    }
+}
+
+class B : A("") {
+    // still can override it
+    override fun memberFun() {
+        super.memberFun() // but cannot call super :)
+    }
+}
+
+class C : A {
+    constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>("")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/ambiguityOnPropertiesWithTheSamePackageName.fir.kt b/compiler/testData/diagnostics/tests/resolve/ambiguityOnPropertiesWithTheSamePackageName.fir.kt
new file mode 100644
index 00000000000..215e3b619ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/ambiguityOnPropertiesWithTheSamePackageName.fir.kt
@@ -0,0 +1,30 @@
+// FILE: a.kt
+package a
+
+class A
+
+// FILE: b.kt
+package b
+
+import a.A
+
+val A.d: Int get() = 1
+
+// FILE: c.kt
+package c
+
+import a.A
+
+val A.d: Int get() = 2
+
+// FILE: d.kt
+
+package d
+
+import a.A
+import b.d
+import c.d
+
+fun A.test() {
+    <!AMBIGUITY!>d<!>
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/ambiguityWithTwoCorrespondingFunctionTypes.fir.kt b/compiler/testData/diagnostics/tests/resolve/ambiguityWithTwoCorrespondingFunctionTypes.fir.kt
new file mode 100644
index 00000000000..f0bbf4e4823
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/ambiguityWithTwoCorrespondingFunctionTypes.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(a: Any, f: ()->Int) = f()
+fun foo(a: Any, f: (Any)->Int) = f(a)
+fun foo(i: Int, f: Int.()->Int) = i.<!UNRESOLVED_REFERENCE!>f<!>()
+
+fun test1() {
+    <!AMBIGUITY!>foo<!>(1) { ->
+        this
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/anonymousObjectFromTopLevelMember.fir.kt b/compiler/testData/diagnostics/tests/resolve/anonymousObjectFromTopLevelMember.fir.kt
new file mode 100644
index 00000000000..f3eb01d0944
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/anonymousObjectFromTopLevelMember.fir.kt
@@ -0,0 +1,24 @@
+interface IFoo {
+    fun foo()
+}
+
+interface IBar
+
+private fun createAnonObject() =
+        object : IFoo, IBar {
+            override fun foo() {}
+            fun qux() {}
+        }
+
+private val propOfAnonObject = object : IFoo, IBar {
+            override fun foo() {}
+            fun qux() {}
+        }
+
+fun useAnonObject() {
+    createAnonObject().foo()
+    createAnonObject().qux()
+
+    propOfAnonObject.foo()
+    propOfAnonObject.qux()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/callableReferenceInCST.fir.kt b/compiler/testData/diagnostics/tests/resolve/callableReferenceInCST.fir.kt
new file mode 100644
index 00000000000..da3429d6c5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/callableReferenceInCST.fir.kt
@@ -0,0 +1,36 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun testWhen(x: Any?) {
+    val y = when (x) {
+        null -> ""
+        else -> <!UNRESOLVED_REFERENCE!>::unresolved<!>
+    }
+}
+
+fun testWhenWithBraces(x: Any?) {
+    val z = when(x) {
+        null -> { "" }
+        else -> { <!UNRESOLVED_REFERENCE!>::unresolved<!> }
+    }
+}
+
+fun testIf(x: Any?) {
+    val y = if (x != null) <!UNRESOLVED_REFERENCE!>::unresolved<!> else null
+}
+
+fun testIfWithBraces(x: Any?) {
+    val z = if (x != null) { <!UNRESOLVED_REFERENCE!>::unresolved<!> } else { null }
+}
+
+fun testElvis(x: Any?) {
+    val y = x ?: <!UNRESOLVED_REFERENCE!>::unresolved<!>
+}
+
+fun testExclExcl() {
+    val y = <!UNRESOLVED_REFERENCE!>:: unresolved<!>!!
+}
+
+fun testTry() {
+    val v = try { <!UNRESOLVED_REFERENCE!>::unresolved<!> } catch (e: Exception) {}
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/capturedTypesInLambdaParameter.fir.kt b/compiler/testData/diagnostics/tests/resolve/capturedTypesInLambdaParameter.fir.kt
new file mode 100644
index 00000000000..7ebe2dacaa1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/capturedTypesInLambdaParameter.fir.kt
@@ -0,0 +1,42 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class B<E>
+
+fun <T> B<T>.foo(f: (T) -> Unit) {}
+fun <T> B<T>.bar(f: (T, T) -> Unit, g: (T, T) -> Unit) {}
+fun <T> B<T>.baz(f: (B<T>) -> Unit) {}
+
+fun number(x: Number) {}
+fun Number.foobar() {}
+
+fun test(b: B<out Number>) {
+    b.foo {
+        it checkType { _<Number>() }
+        it.toInt()
+    }
+
+    b.foo { x ->
+        x checkType { _<Number>() }
+        x.toInt()
+    }
+
+    b.bar({ x, y ->
+        x checkType { _<Number>() }
+        y checkType { _<Number>() }
+        x.toInt()
+        y.toInt()
+    }) { u, w ->
+        u checkType { _<Number>() }
+        w checkType { _<Number>() }
+
+        u.toInt()
+        w.toInt()
+    }
+
+    b.foo(::number)
+    b.foo(Number::foobar)
+
+    b.baz {
+        b -> b checkType { _<B<out Number>>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/constructorVsCompanion.fir.kt b/compiler/testData/diagnostics/tests/resolve/constructorVsCompanion.fir.kt
new file mode 100644
index 00000000000..1f446ed239b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/constructorVsCompanion.fir.kt
@@ -0,0 +1,23 @@
+class A private constructor()
+
+class B {
+    private companion object
+}
+
+class C(val x: Int)
+
+class D private constructor() {
+    companion object
+}
+
+class E private constructor() {
+    companion object {
+        operator fun invoke(x: Int) = x
+    }
+}
+
+val a = A
+val b = B
+val c = C
+val d = D
+val e = <!INAPPLICABLE_CANDIDATE!>E<!>(42)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedFunctionType.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedFunctionType.fir.kt
new file mode 100644
index 00000000000..04030ea4324
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedFunctionType.fir.kt
@@ -0,0 +1,57 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+@Target(AnnotationTarget.TYPE)
+@DslMarker
+annotation class MyDsl
+
+interface A {
+    fun foo()
+}
+
+interface B {
+    fun bar()
+}
+
+fun baz1(x: (@MyDsl A).() -> Unit) {}
+fun baz2(x: (@MyDsl B).() -> Unit) {}
+fun baz3(x: @MyDsl A.() -> Unit) {}
+fun baz4(x: @MyDsl B.() -> Unit) {}
+
+fun @MyDsl A.baz5() {
+    baz4 {
+        bar()
+        foo()
+    }
+}
+
+fun main() {
+    baz1 {
+        baz2 {
+            bar()
+            foo()
+        }
+    }
+
+    baz3 {
+        baz2 {
+            bar()
+            foo()
+        }
+    }
+
+    baz1 {
+        baz4 {
+            bar()
+            foo()
+        }
+    }
+
+    baz3 {
+        baz4 {
+            bar()
+            foo()
+        }
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedFunctionType_1_4.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedFunctionType_1_4.fir.kt
new file mode 100644
index 00000000000..8ee13aff80d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedFunctionType_1_4.fir.kt
@@ -0,0 +1,58 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !LANGUAGE: +DslMarkerOnFunctionTypeReceiver
+// !WITH_NEW_INFERENCE
+
+@Target(AnnotationTarget.TYPE)
+@DslMarker
+annotation class MyDsl
+
+interface A {
+    fun foo()
+}
+
+interface B {
+    fun bar()
+}
+
+fun baz1(x: (@MyDsl A).() -> Unit) {}
+fun baz2(x: (@MyDsl B).() -> Unit) {}
+fun baz3(x: @MyDsl A.() -> Unit) {}
+fun baz4(x: @MyDsl B.() -> Unit) {}
+
+fun @MyDsl A.baz5() {
+    baz4 {
+        bar()
+        foo()
+    }
+}
+
+fun main() {
+    baz1 {
+        baz2 {
+            bar()
+            foo()
+        }
+    }
+
+    baz3 {
+        baz2 {
+            bar()
+            foo()
+        }
+    }
+
+    baz1 {
+        baz4 {
+            bar()
+            foo()
+        }
+    }
+
+    baz3 {
+        baz4 {
+            bar()
+            foo()
+        }
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedTypeArgument.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedTypeArgument.fir.kt
new file mode 100644
index 00000000000..6821b6aa407
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/annotatedTypeArgument.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun <T> foo(x: T.() -> Unit) {}
+fun <E> bar(x: E.() -> Unit) {}
+
+fun test() {
+    foo<@Ann A> {
+        a()
+        bar<@Ann B> {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/dslMarkerOnTypealias.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/dslMarkerOnTypealias.fir.kt
new file mode 100644
index 00000000000..763584c4628
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/dslMarkerOnTypealias.fir.kt
@@ -0,0 +1,28 @@
+@DslMarker
+@Target(AnnotationTarget.CLASS, AnnotationTarget.TYPEALIAS)
+annotation class XMarker
+
+@XMarker
+class Foo
+
+class Bar
+
+@XMarker
+typealias XBar = Bar
+
+typealias XXBar = XBar
+
+fun Foo.foo(body: Foo.() -> Unit) = <!INAPPLICABLE_CANDIDATE!>body<!>()
+fun Foo.xbar(body: XBar.() -> Unit) = Bar().<!UNRESOLVED_REFERENCE!>body<!>()
+fun Foo.xxbar(body: XXBar.() -> Unit) = Bar().<!UNRESOLVED_REFERENCE!>body<!>()
+
+fun test() {
+    Foo().foo {
+        <!UNRESOLVED_REFERENCE!>xbar<!> {
+            <!UNRESOLVED_REFERENCE!>foo<!> {}
+        }
+        <!UNRESOLVED_REFERENCE!>xxbar<!> {
+            <!UNRESOLVED_REFERENCE!>foo<!> {}
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/dslMarkerWithTypealiasRecursion.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/dslMarkerWithTypealiasRecursion.fir.kt
new file mode 100644
index 00000000000..90e7fefe98d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/dslMarkerWithTypealiasRecursion.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+@DslMarker
+@Target(AnnotationTarget.CLASS, AnnotationTarget.TYPEALIAS)
+annotation class XMarker
+
+@XMarker
+class Foo
+
+class Bar
+
+typealias YBar = ZBar
+typealias ZBar = <!OTHER_ERROR!>YBar<!>
+
+fun Foo.foo(body: Foo.() -> Unit) = <!INAPPLICABLE_CANDIDATE!>body<!>()
+fun Foo.zbar(body: ZBar.() -> Unit) = Bar().<!UNRESOLVED_REFERENCE!>body<!>()
+
+fun test() {
+    Foo().foo {
+        <!UNRESOLVED_REFERENCE!>zbar<!> {
+            <!UNRESOLVED_REFERENCE!>foo<!> {}
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/inheritedMarker.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/inheritedMarker.fir.kt
new file mode 100644
index 00000000000..83a3ea54e79
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/inheritedMarker.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+interface Common
+interface C : Common
+interface D : C
+
+class A : C {
+    fun a() = 1
+}
+
+class B : D {
+    fun b() = 2
+}
+
+fun foo(x: A.() -> Unit) {}
+fun bar(x: B.() -> Unit) {}
+
+fun test() {
+    foo {
+        a()
+        bar {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/insideTopLevelExtension.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/insideTopLevelExtension.fir.kt
new file mode 100644
index 00000000000..bbed69f4773
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/insideTopLevelExtension.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+class A {
+    fun a() = 1
+}
+
+@Ann
+class B {
+    fun b() = 2
+}
+
+fun bar(x: B.() -> Unit) {}
+
+fun A.test() {
+    bar {
+        a()
+        this@test.a()
+        b()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/insideTopLevelExtensionAnnotatedType.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/insideTopLevelExtensionAnnotatedType.fir.kt
new file mode 100644
index 00000000000..dcdcd748b25
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/insideTopLevelExtensionAnnotatedType.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun bar(x: (@Ann B).() -> Unit) {}
+
+fun @Ann A.test() {
+    bar {
+        a()
+        this@test.a()
+        b()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/kt29948.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/kt29948.fir.kt
new file mode 100644
index 00000000000..7dd88e1b21c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/kt29948.fir.kt
@@ -0,0 +1,19 @@
+@DslMarker
+annotation class MyDsl
+
+@MyDsl
+interface Foo<T> {
+    val x: Int
+}
+
+val Foo<*>.bad: Int get() = x
+
+fun Foo<*>.badFun(): Int = x
+
+val Foo<Int>.good: Int get() = x
+
+fun test(foo: Foo<*>) {
+    foo.apply {
+        x
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/kt31360.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/kt31360.fir.kt
new file mode 100644
index 00000000000..9b3b0501a2b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/kt31360.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+@DslMarker
+annotation class MyDsl
+
+@MyDsl
+interface Scope<A, B> {
+    val something: A
+    val value: B
+}
+fun scoped1(block: Scope<Int, String>.() -> Unit) {}
+fun scoped2(block: Scope<*, String>.() -> Unit) {}
+
+val <T> Scope<*, T>.property: T get() = value
+
+fun f() {
+    scoped1 {
+        value
+        property
+    }
+    scoped2 {
+        value
+        property
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/markedReceiverWithCapturedTypeArgument.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/markedReceiverWithCapturedTypeArgument.fir.kt
new file mode 100644
index 00000000000..8349ec26541
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/markedReceiverWithCapturedTypeArgument.fir.kt
@@ -0,0 +1,11 @@
+@DslMarker
+annotation class AnnMarker
+
+@AnnMarker
+class Inv<T> {
+    fun bar() {}
+}
+
+fun Inv<*>.foo() {
+    bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/markersIntersection.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/markersIntersection.fir.kt
new file mode 100644
index 00000000000..8eb2a6ceed0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/markersIntersection.fir.kt
@@ -0,0 +1,93 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class L1
+
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class L2
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun foo1(x: (@L1 A).() -> Unit) {}
+fun foo2(x: (@L2 A).() -> Unit) {}
+
+fun foo12(x: (@L1 @L2 A).() -> Unit) {}
+
+fun bar1(x: (@L1 B).() -> Unit) {}
+fun bar2(x: (@L2 B).() -> Unit) {}
+
+fun <T> bar1t(q: T, x: (@L1 T).() -> Unit) {}
+
+fun test() {
+    foo12 {
+        a()
+        bar1 {
+            a()
+            b()
+        }
+
+        bar2 {
+            a()
+            b()
+        }
+    }
+
+    bar1 {
+        b()
+        foo12 {
+            a()
+            b()
+        }
+    }
+
+    bar2 {
+        b()
+        foo12 {
+            a()
+            b()
+        }
+    }
+
+    foo2 {
+        bar1t(this) {
+            a()
+            bar1 {
+                a()
+                b()
+            }
+
+            bar2 {
+                a()
+                b()
+            }
+        }
+    }
+
+    bar1 {
+        b()
+        foo2 {
+            bar1t(this) {
+                a()
+                b()
+            }
+        }
+    }
+
+    bar2 {
+        b()
+        foo2 {
+            bar1t(this) {
+                a()
+                b()
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/nestedWithSameReceiver.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/nestedWithSameReceiver.fir.kt
new file mode 100644
index 00000000000..9e08430d307
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/nestedWithSameReceiver.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun foo(x: (@Ann A).() -> Unit) {}
+fun bar(x: (@Ann B).() -> Unit) {}
+
+fun test() {
+    foo {
+        a()
+        foo l1@{
+            a()
+            bar l2@{
+                a()
+                this@l1.a()
+                b()
+
+                foo l3@{
+                    a()
+                    b()
+                    this@l2.b()
+                    bar {
+                        a()
+                        this@l3.a()
+                        b()
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/properties.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/properties.fir.kt
new file mode 100644
index 00000000000..2c75099988a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/properties.fir.kt
@@ -0,0 +1,62 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+class A {
+    var a = 1
+}
+
+var A.a1: Int
+    get() = 1
+    set(value) {}
+
+@Ann
+class B {
+    var b = 2
+}
+
+var B.b1: Int
+    get() = 1
+    set(value) {}
+
+fun foo(x: A.() -> Unit) {}
+fun bar(x: B.() -> Unit) {}
+
+fun test() {
+    foo {
+        a + 1
+        a += a + 1
+        a++
+
+        a1 + 1
+        a1 += a1 + 1
+        a1++
+
+        bar {
+            a + 1
+            a += a + 1
+            a++
+
+            a1 + 1
+            a1 += a1 + 1
+            a1++
+
+            this@foo.a + 1
+            this@foo.a += this@foo.a + 1
+            this@foo.a++
+
+            this@foo.a1 + 1
+            this@foo.a1 += this@foo.a1 + 1
+            this@foo.a1++
+
+            b + 1
+            b += b + 1
+            b++
+
+            b1 + 1
+            b1 += b1 + 1
+            b1++
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/simpleAnnotatedClasses.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/simpleAnnotatedClasses.fir.kt
new file mode 100644
index 00000000000..dd96e9a7fd4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/simpleAnnotatedClasses.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+class A {
+    fun a() = 1
+}
+
+@Ann
+class B {
+    fun b() = 2
+}
+
+fun foo(x: A.() -> Unit) {}
+fun bar(x: B.() -> Unit) {}
+
+fun test() {
+    foo {
+        a()
+        bar {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/simpleAnnotatedTypes.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/simpleAnnotatedTypes.fir.kt
new file mode 100644
index 00000000000..5603ec6df14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/simpleAnnotatedTypes.fir.kt
@@ -0,0 +1,26 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun foo(x: (@Ann A).() -> Unit) {}
+fun bar(x: (@Ann B).() -> Unit) {}
+
+fun test() {
+    foo {
+        a()
+        bar {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/substitutedReceiverAnnotatedClasses.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/substitutedReceiverAnnotatedClasses.fir.kt
new file mode 100644
index 00000000000..24d4eb3e602
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/substitutedReceiverAnnotatedClasses.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+class A {
+    fun a() = 1
+}
+
+@Ann
+class B {
+    fun b() = 2
+}
+
+fun <T> foo(x: T.() -> Unit) {}
+fun <E> bar(x: E.() -> Unit) {}
+
+fun test() {
+    foo<A> {
+        a()
+        bar<B> {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/substitutedReceiverAnnotatedType.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/substitutedReceiverAnnotatedType.fir.kt
new file mode 100644
index 00000000000..ab79d02f572
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/substitutedReceiverAnnotatedType.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun <T> foo(x: (@Ann T).() -> Unit) {}
+fun <E> bar(x: (@Ann E).() -> Unit) {}
+
+fun test() {
+    foo<A> {
+        a()
+        bar<B> {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/threeImplicitReceivers.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/threeImplicitReceivers.fir.kt
new file mode 100644
index 00000000000..62179bd9710
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/threeImplicitReceivers.fir.kt
@@ -0,0 +1,111 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann1
+
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann2
+
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann3
+
+class A {
+    operator fun B.invoke() {}
+
+    val B.y: D get() = D()
+}
+
+class B
+
+class C {
+    operator fun D.invoke() {}
+
+    val D.x: B get() = B()
+}
+
+class D
+
+fun foo(x: (@Ann1 A).() -> Unit) {}
+fun bar(x: (@Ann2 B).() -> Unit) {}
+fun baz(x: (@Ann3 C).() -> Unit) {}
+fun foo1(x: (@Ann1 D).() -> Unit) {}
+fun foo2(x: (@Ann2 D).() -> Unit) {}
+fun foo3(x: (@Ann3 D).() -> Unit) {}
+
+fun test() {
+    foo {
+        bar {
+            baz {
+                y()
+
+                <!UNRESOLVED_REFERENCE!>x<!>()
+
+                with(D()) {
+                    x()
+                }
+                D().x()
+
+                foo1 {
+                    x()
+                    y()
+
+                    with(A()) {
+                        x()
+                        y()
+                    }
+
+                    with(D()) {
+                        x()
+                    }
+                    D().x()
+                }
+
+                foo2 {
+                    x()
+                    y()
+                }
+
+                foo3 {
+                    x()
+                    y()
+                }
+            }
+        }
+    }
+
+    foo1 {
+        foo {
+            baz {
+                bar {
+                    x()
+                    y()
+                }
+            }
+        }
+    }
+
+    foo2 {
+        foo {
+            baz {
+                bar {
+                    x()
+                    y()
+                }
+            }
+        }
+    }
+
+    foo3 {
+        foo {
+            baz {
+                bar {
+                    x()
+                    y()
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/threeImplicitReceivers2.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/threeImplicitReceivers2.fir.kt
new file mode 100644
index 00000000000..f92766208d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/threeImplicitReceivers2.fir.kt
@@ -0,0 +1,106 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann1
+
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann2
+
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann3
+
+class A {
+    val B.y: (C.() -> Unit) get() = null!!
+}
+
+class B
+
+class C {
+    val D.x: (A.() -> Unit) get() = null!!
+}
+
+class D
+
+fun foo(x: (@Ann1 A).() -> Unit) {}
+fun bar(x: (@Ann2 B).() -> Unit) {}
+fun baz(x: (@Ann3 C).() -> Unit) {}
+fun foo1(x: (@Ann1 D).() -> Unit) {}
+fun foo2(x: (@Ann2 D).() -> Unit) {}
+fun foo3(x: (@Ann3 D).() -> Unit) {}
+
+fun test() {
+    foo {
+        bar {
+            baz {
+                <!INAPPLICABLE_CANDIDATE!>y<!>()
+
+                <!UNRESOLVED_REFERENCE!>x<!>()
+
+                with(D()) {
+                    <!INAPPLICABLE_CANDIDATE!>x<!>()
+                }
+
+                foo1 {
+                    <!INAPPLICABLE_CANDIDATE!>x<!>()
+                    <!INAPPLICABLE_CANDIDATE!>y<!>()
+
+                    with(A()) {
+                        <!INAPPLICABLE_CANDIDATE!>x<!>()
+                        <!INAPPLICABLE_CANDIDATE!>y<!>()
+                    }
+
+                    with(D()) {
+                        <!INAPPLICABLE_CANDIDATE!>x<!>()
+                    }
+                    A().<!UNRESOLVED_REFERENCE!>x<!>()
+                }
+
+                foo2 {
+                    <!INAPPLICABLE_CANDIDATE!>x<!>()
+                    <!INAPPLICABLE_CANDIDATE!>y<!>()
+                }
+
+                foo3 {
+                    <!INAPPLICABLE_CANDIDATE!>x<!>()
+                    <!INAPPLICABLE_CANDIDATE!>y<!>()
+                }
+            }
+        }
+    }
+
+    foo1 {
+        foo {
+            baz {
+                bar {
+                    <!INAPPLICABLE_CANDIDATE!>x<!>()
+                    <!INAPPLICABLE_CANDIDATE!>y<!>()
+                }
+            }
+        }
+    }
+
+    foo2 {
+        foo {
+            baz {
+                bar {
+                    <!INAPPLICABLE_CANDIDATE!>x<!>()
+                    <!INAPPLICABLE_CANDIDATE!>y<!>()
+                }
+            }
+        }
+    }
+
+    foo3 {
+        foo {
+            baz {
+                bar {
+                    <!INAPPLICABLE_CANDIDATE!>x<!>()
+                    <!INAPPLICABLE_CANDIDATE!>y<!>()
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/twoImplicitReceivers.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/twoImplicitReceivers.fir.kt
new file mode 100644
index 00000000000..6d1cff02306
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/twoImplicitReceivers.fir.kt
@@ -0,0 +1,102 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann1
+
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann2
+
+class A {
+    fun D.extA() {}
+}
+
+class B {
+    fun D.extB() {}
+}
+
+class D
+
+fun foo(x: (@Ann1 A).() -> Unit) {}
+fun bar(x: (@Ann2 B).() -> Unit) {}
+fun baz(x: (@Ann1 D).() -> Unit) {}
+
+fun test() {
+    foo {
+        bar {
+            baz {
+                extA()
+                extB()
+
+                D().extA()
+                D().extB()
+
+                with(D()) {
+                    extA()
+                    extB()
+                }
+            }
+        }
+    }
+
+    foo {
+        baz {
+            extA()
+            D().extA()
+
+            bar {
+                extA()
+                extB()
+
+                D().extA()
+                D().extB()
+
+                with(D()) {
+                    extA()
+                    extB()
+                }
+            }
+        }
+    }
+
+    baz {
+        foo {
+            extA()
+            D().extA()
+
+            bar {
+                extA()
+                extB()
+
+                D().extA()
+                D().extB()
+
+                with(D()) {
+                    extA()
+                    extB()
+                }
+            }
+        }
+    }
+
+    baz {
+        bar {
+            extB()
+
+            D().extB()
+
+            foo {
+                extA()
+                extB()
+
+                D().extA()
+                D().extB()
+
+                with(D()) {
+                    extA()
+                    extB()
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/twoLanguages.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/twoLanguages.fir.kt
new file mode 100644
index 00000000000..dded7a3c332
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/twoLanguages.fir.kt
@@ -0,0 +1,104 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class L1
+
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class L2
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun foo1(x: (@L1 A).() -> Unit) {}
+fun foo2(x: (@L2 A).() -> Unit) {}
+fun bar1(x: (@L1 B).() -> Unit) {}
+fun bar2(x: (@L2 B).() -> Unit) {}
+
+fun test() {
+    foo1 {
+        a()
+
+        foo2 {
+            a()
+
+            bar1 {
+                a()
+                b()
+                bar2 {
+                    a()
+                    b()
+                }
+            }
+
+            bar2 {
+                a()
+                b()
+            }
+        }
+
+        bar1 {
+            a()
+            b()
+            bar2 {
+                a()
+                b()
+            }
+        }
+
+        bar2 {
+            a()
+            b()
+        }
+    }
+
+    foo2 {
+        a()
+
+        bar1 {
+            a()
+            b()
+            bar2 {
+                a()
+                b()
+            }
+        }
+
+        bar2 {
+            a()
+            b()
+        }
+    }
+
+    bar1 {
+        b()
+        bar2 {
+            b()
+        }
+    }
+
+    bar2 {
+        b()
+    }
+
+    foo1 {
+        bar1 {
+            a()
+            b()
+            foo2 {
+                a()
+                b()
+
+                bar2 {
+                    a()
+                    b()
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/unsupportedFeature.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/unsupportedFeature.fir.kt
new file mode 100644
index 00000000000..e67767e06d7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/unsupportedFeature.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: -DslMarkersSupport
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+class A {
+    fun a() = 1
+}
+
+@Ann
+class B {
+    fun b() = 2
+}
+
+fun foo(x: A.() -> Unit) {}
+fun bar(x: B.() -> Unit) {}
+
+fun test() {
+    foo {
+        a()
+        bar {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/useOfExtensions.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/useOfExtensions.fir.kt
new file mode 100644
index 00000000000..67f3907fd21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/useOfExtensions.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+class A
+
+fun A.a() = 1
+
+@Ann
+class B
+
+fun B.b() = 2
+
+fun foo(x: A.() -> Unit) {}
+fun bar(x: B.() -> Unit) {}
+
+fun test() {
+    foo {
+        a()
+        bar {
+            a()
+            this@foo.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/usingWith.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/usingWith.fir.kt
new file mode 100644
index 00000000000..657f48d8e9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/usingWith.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+annotation class Ann
+
+@Ann
+class A {
+    fun a() = 1
+}
+
+@Ann
+class B {
+    fun b() = 2
+}
+
+fun test(a: A, b: B) {
+    with(a) l1@{
+        a()
+        with(b) {
+            a()
+            this@l1.a()
+            b()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/dslMarker/usingWithThis.fir.kt b/compiler/testData/diagnostics/tests/resolve/dslMarker/usingWithThis.fir.kt
new file mode 100644
index 00000000000..91967af6ae4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/dslMarker/usingWithThis.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@DslMarker
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+class A {
+    fun a() = 1
+}
+
+class B {
+    fun b() = 2
+}
+
+fun foo(x: (@Ann A).() -> Unit) {}
+fun bar(x: (@Ann B).() -> Unit) {}
+
+fun test() {
+    foo {
+        with(this) l1@{
+            a()
+            bar {
+                with(this) {
+                    a()
+                    this@l1.a()
+                    b()
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/implicitReceiverProperty.fir.kt b/compiler/testData/diagnostics/tests/resolve/implicitReceiverProperty.fir.kt
new file mode 100644
index 00000000000..d478dd2a6ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/implicitReceiverProperty.fir.kt
@@ -0,0 +1,33 @@
+// FILE: a.kt
+package a
+
+class A(val b: String) {
+    companion object {
+        val c: String = ""
+    }
+
+    fun mtd() = c.length
+}
+
+// FILE: b.kt
+package b
+
+// FILE: c.kt
+package c
+
+// FILE: test.kt
+package test
+
+import a.A
+
+fun <T, R> T.with(f: T.() -> R) = <!INAPPLICABLE_CANDIDATE!>f<!>()
+
+fun A.extFun1() = b.length
+
+// fun A.extFun2() = c.length // TODO fix KT-9953
+
+val x1 = A("").with { b.<!UNRESOLVED_REFERENCE!>length<!> }
+
+// val x2 = A("").with { c.length } // TODO fix KT-9953
+
+val x3 = A.with { c.<!UNRESOLVED_REFERENCE!>length<!> }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/incompleteConstructorInvocation.fir.kt b/compiler/testData/diagnostics/tests/resolve/incompleteConstructorInvocation.fir.kt
new file mode 100644
index 00000000000..060b8628bd9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/incompleteConstructorInvocation.fir.kt
@@ -0,0 +1,10 @@
+package p
+
+class X<V>(provider: () -> V, trackValue: Boolean) {
+}
+
+class B {
+    val c = <!INAPPLICABLE_CANDIDATE!>X<!><String> {
+        "e"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/inferenceInLinkedLambdas.fir.kt b/compiler/testData/diagnostics/tests/resolve/inferenceInLinkedLambdas.fir.kt
new file mode 100644
index 00000000000..fd41b8a4972
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/inferenceInLinkedLambdas.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+fun <T, R> foo(first: () -> T, second: (T) -> R): R = throw Exception()
+fun test() {
+    val r = foo( { 4 }, { "${it + 1}" } )
+    r checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/inferenceInLinkedLambdasDependentOnExpectedType.fir.kt b/compiler/testData/diagnostics/tests/resolve/inferenceInLinkedLambdasDependentOnExpectedType.fir.kt
new file mode 100644
index 00000000000..c342c179705
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/inferenceInLinkedLambdasDependentOnExpectedType.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> foo(f: () -> Collection<T>, p: (T) -> Boolean): Collection<T> = throw Exception()
+
+fun <T> emptyList(): List<T> = throw Exception()
+
+fun test(): Collection<Int> = foo({ emptyList<Int>() }, { x -> x > 0 })
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/KT-4372.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/KT-4372.fir.kt
new file mode 100644
index 00000000000..b33f336a2af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/KT-4372.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+//KT-4372 Invalid error position and failing to resolve invoke with receiver from other module
+
+class Foo<TInner, TOuter> {
+    fun invoke(content: TInner.() -> Unit) {
+    }
+}
+
+// comment this function to fix the error below
+fun <TInner, TOuter> Foo<TInner, TOuter>.invoke(name: String, content: TInner.() -> Unit) {}
+
+enum class EnumClass(val x: String) {}
+object Y {
+    val x = javaClass<EnumClass>() // javaClass unresolved in any file in this module
+}
+
+//declarations from library
+val <T> T.javaClass : Class<T>
+    get() = throw Exception()
+
+fun <reified T> javaClass() : Class<T> = throw Exception()
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/ambiguityForInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/ambiguityForInvoke.fir.kt
new file mode 100644
index 00000000000..dd3251bb346
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/ambiguityForInvoke.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+        
+fun Int.invoke(i: Int, a: Any) {}
+fun Int.invoke(a: Any, i: Int) {}
+
+fun foo(i: Int) {
+    <!AMBIGUITY!>i<!>(1, 1)
+
+    <!AMBIGUITY!>5(1, 2)<!>
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/invisibleInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/invisibleInvoke.fir.kt
new file mode 100644
index 00000000000..b593f3be4c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/invisibleInvoke.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class My {
+    private operator fun Int.invoke(s: String) {}
+}
+
+fun My.foo(i: Int) {
+    <!INAPPLICABLE_CANDIDATE!>i<!>("")
+    <!INAPPLICABLE_CANDIDATE!>1("")<!>
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/receiverPresenceErrorForInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/receiverPresenceErrorForInvoke.fir.kt
new file mode 100644
index 00000000000..027ba798f01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/receiverPresenceErrorForInvoke.fir.kt
@@ -0,0 +1,11 @@
+fun test1(f: String.() -> Unit) {
+    <!INAPPLICABLE_CANDIDATE!>(f)()<!>
+
+    <!INAPPLICABLE_CANDIDATE!>f<!>()
+}
+
+fun test2(f: (Int) -> Int) {
+    1.<!UNRESOLVED_REFERENCE!>f<!>(2)
+
+    2.<!UNRESOLVED_REFERENCE!>(f)(2)<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/typeInferenceErrorForInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/typeInferenceErrorForInvoke.fir.kt
new file mode 100644
index 00000000000..0874328e546
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/typeInferenceErrorForInvoke.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T>
+
+operator fun <T> T.invoke(a: A<T>) {}
+
+fun foo(s: String, ai: A<Int>) {
+    1(ai)
+
+    <!INAPPLICABLE_CANDIDATE!>s<!>(ai)
+
+    <!INAPPLICABLE_CANDIDATE!>""(ai)<!>
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/unresolvedInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/unresolvedInvoke.fir.kt
new file mode 100644
index 00000000000..0874f5b7d95
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/unresolvedInvoke.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+fun foo(i: Int) {
+    <!UNRESOLVED_REFERENCE!>i<!>()
+    <!UNRESOLVED_REFERENCE!>1()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/unsafeCallWithInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/unsafeCallWithInvoke.fir.kt
new file mode 100644
index 00000000000..9ec457efedc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/unsafeCallWithInvoke.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+operator fun String.invoke(i: Int) {}
+
+fun foo(s: String?) {
+    <!INAPPLICABLE_CANDIDATE!>s<!>(1)
+
+    <!INAPPLICABLE_CANDIDATE!>(s ?: null)(1)<!>
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/wrongReceiverForInvokeOnExpression.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/wrongReceiverForInvokeOnExpression.fir.kt
new file mode 100644
index 00000000000..3c2289bab4d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/wrongReceiverForInvokeOnExpression.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+
+fun test1() {
+    1. <!UNRESOLVED_REFERENCE!>(fun String.(i: Int) = i )(1)<!>
+    1.<!UNRESOLVED_REFERENCE!>(label@ fun String.(i: Int) = i )(1)<!>
+}
+
+fun test2(f: String.(Int) -> Unit) {
+    11.<!UNRESOLVED_REFERENCE!>(f)(1)<!>
+    11.<!UNRESOLVED_REFERENCE!>(f)()<!>
+}
+
+fun test3() {
+    fun foo(): String.(Int) -> Unit = {}
+
+    1.<!UNRESOLVED_REFERENCE!>(foo())(1)<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/errors/wrongReceiverTypeForInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/errors/wrongReceiverTypeForInvoke.fir.kt
new file mode 100644
index 00000000000..e99d2def1c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/errors/wrongReceiverTypeForInvoke.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun String.invoke(i: Int) {}
+
+fun foo(i: Int) {
+    <!INAPPLICABLE_CANDIDATE!>i<!>(1)
+
+    <!INAPPLICABLE_CANDIDATE!>1(1)<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/extensionValueAsNonExtension.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/extensionValueAsNonExtension.fir.kt
new file mode 100644
index 00000000000..ce28c42c796
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/extensionValueAsNonExtension.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+class A
+
+fun test(foo: A.() -> Int, a: A) {
+    val b: Int = foo(a)
+    val c: Int = (foo)(a)
+}
+
+class B {
+    val foo: A.() -> Int = null!!
+
+    init {
+        val b: Int = foo(A())
+    }
+}
+
+fun foo(): A.() -> Int {
+    val b: Int = foo()(A())
+    val c: Int = (foo())(A())
+
+    return null!!
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/functionExpectedWhenSeveralInvokesExist.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/functionExpectedWhenSeveralInvokesExist.fir.kt
new file mode 100644
index 00000000000..5beb96a3b06
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/functionExpectedWhenSeveralInvokesExist.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun Int.invoke(a: Int) {}
+fun Int.invoke(a: Int, b: Int) {}
+
+class SomeClass
+
+fun test(identifier: SomeClass, fn: String.() -> Unit) {
+    <!INAPPLICABLE_CANDIDATE!>identifier<!>()
+    <!INAPPLICABLE_CANDIDATE!>identifier<!>(123)
+    <!INAPPLICABLE_CANDIDATE!>identifier<!>(1, 2)
+    1.<!UNRESOLVED_REFERENCE!>fn<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/implicitInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/implicitInvoke.fir.kt
new file mode 100644
index 00000000000..3f929db31fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/implicitInvoke.fir.kt
@@ -0,0 +1,33 @@
+class B
+
+class A {
+    operator fun B.invoke() = 4
+}
+
+class X {
+    operator fun invoke() = 3
+}
+
+fun test(a: A, b: B) {
+    with (a) {
+        b()
+        (b)()
+    }
+
+    X()()
+    val x = X()
+    x()
+    (x)()
+}
+
+fun test(c: () -> String, e: Int.() -> String) {
+    c()
+    (c)()
+
+    3.<!UNRESOLVED_REFERENCE!>e<!>()
+    3.<!UNRESOLVED_REFERENCE!>(e)()<!>
+    with(3) {
+        <!INAPPLICABLE_CANDIDATE!>e<!>()
+        <!INAPPLICABLE_CANDIDATE!>(e)()<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/invokeAndSmartCast.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAndSmartCast.fir.kt
new file mode 100644
index 00000000000..3a5a8a49df6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAndSmartCast.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+class A(val x: (String.() -> Unit)?)
+
+fun test(a: A) {
+    if (a.x != null) {
+        "".<!UNRESOLVED_REFERENCE!>(a.x)()<!>
+        a.x("") // todo
+        (a.x)("")
+    }
+    "".<!UNRESOLVED_REFERENCE!>(a.x)()<!>
+    a.<!INAPPLICABLE_CANDIDATE!>x<!>("")
+    <!INAPPLICABLE_CANDIDATE!>(a.x)("")<!>
+
+    with("") {
+        a.<!INAPPLICABLE_CANDIDATE!>x<!>()
+        <!INAPPLICABLE_CANDIDATE!>(a.x)()<!>
+        if (a.x != null) {
+            a.<!INAPPLICABLE_CANDIDATE!>x<!>() // todo
+            <!INAPPLICABLE_CANDIDATE!>(a.x)()<!>
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsExtension.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsExtension.fir.kt
new file mode 100644
index 00000000000..f4f9bacf244
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsExtension.fir.kt
@@ -0,0 +1,61 @@
+class Foo {}
+
+operator fun Foo.invoke() {}
+
+//no variable
+fun test(foo: Foo) {
+    foo()
+}
+
+//variable as member
+interface A {
+    val foo: Foo
+}
+
+
+fun test(a: A) {
+    a.foo()
+
+    with (a) {
+        foo()
+    }
+}
+
+//variable as extension
+interface B {
+}
+val B.foo: Foo
+    get() = Foo()
+
+fun test(b: B) {
+    b.foo()
+
+    with (b) {
+        foo()
+    }
+}
+
+//variable as member extension
+interface C
+
+interface D {
+    val C.foo: Foo
+
+    fun test(c: C) {
+        c.foo()
+
+        with (c) {
+            foo()
+        }
+    }
+}
+
+fun test(d: D, c: C) {
+    with (d) {
+        c.foo()
+
+        with (c) {
+            foo()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMember.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMember.fir.kt
new file mode 100644
index 00000000000..fd841f6fe7e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMember.fir.kt
@@ -0,0 +1,60 @@
+class Foo {
+    operator fun invoke() {}
+}
+
+//no variable
+fun test(foo: Foo) {
+    foo()
+}
+
+//variable as member
+interface A {
+    val foo: Foo
+}
+
+fun test(a: A) {
+    a.foo()
+
+    with (a) {
+        foo()
+    }
+}
+
+//variable as extension
+interface B {}
+val B.foo: Foo
+    get() = Foo()
+
+
+fun test(b: B) {
+    b.foo()
+
+    with (b) {
+        foo()
+    }
+}
+
+//variable as member extension
+interface C
+
+interface D {
+    val C.foo: Foo
+
+    fun test(c: C) {
+        c.foo()
+
+        with (c) {
+            foo()
+        }
+    }
+}
+
+fun test(d: D, c: C) {
+    with (d) {
+        c.foo()
+
+        with (c) {
+            foo()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMemberExtension.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMemberExtension.fir.kt
new file mode 100644
index 00000000000..803ee1c22b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMemberExtension.fir.kt
@@ -0,0 +1,123 @@
+class Foo
+
+//no variable
+interface A {
+    operator fun Foo.invoke() {}
+
+    fun test(foo: Foo) {
+        foo()
+    }
+}
+
+//variable as member
+interface B {
+    val foo: Foo
+}
+
+class C {
+    operator fun Foo.invoke() {}
+
+    fun test(b: B) {
+        b.foo()
+
+        with (b) {
+            foo()
+        }
+    }
+}
+
+fun test(c: C, b: B) {
+    with (c) {
+        b.foo()
+
+        with (b) {
+            foo()
+        }
+    }
+}
+
+
+//variable as extension,
+interface D {
+}
+val D.foo: Foo
+    get() = Foo()
+
+class E {
+    operator fun Foo.invoke() {}
+
+    fun test(d: D) {
+        d.foo()
+
+        with (d) {
+            foo()
+        }
+    }
+}
+
+fun test(e: E, d: D) {
+    with (e) {
+        d.foo()
+
+        with (d) {
+            foo()
+        }
+    }
+}
+
+//variable as member extension
+interface F
+
+interface G {
+    val F.foo: Foo
+    operator fun Foo.invoke()
+
+    fun test(f: F) {
+        f.foo()
+
+        with (f) {
+            foo()
+        }
+    }
+}
+
+fun test(g: G, f: F) {
+    with (g) {
+        f.foo()
+
+        with (f) {
+            foo()
+        }
+    }
+}
+
+//variable as member extension (2)
+interface X
+
+interface U {
+    val X.foo: Foo
+}
+
+interface V {
+    operator fun Foo.invoke() {}
+
+    fun U.test(x: X) {
+        x.foo()
+
+        with (x) {
+            foo()
+        }
+    }
+}
+
+fun test(u: U, v: V, x: X) {
+    with (v) {
+        with (u) {
+            x.foo()
+
+            with (x) {
+                foo()
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMemberExtensionToExplicitReceiver.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMemberExtensionToExplicitReceiver.fir.kt
new file mode 100644
index 00000000000..e4dda926053
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/invokeAsMemberExtensionToExplicitReceiver.fir.kt
@@ -0,0 +1,12 @@
+interface A
+interface Foo {
+    operator fun A.invoke()
+}
+
+fun test(a: A, foo: Foo) {
+    a.<!UNRESOLVED_REFERENCE!>foo<!>()
+}
+
+fun test(a: Int, foo: Int.()->Unit) {
+    a.<!UNRESOLVED_REFERENCE!>foo<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/invokeNonExtensionLambdaInContext.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/invokeNonExtensionLambdaInContext.fir.kt
new file mode 100644
index 00000000000..901f589de5d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/invokeNonExtensionLambdaInContext.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_ANONYMOUS_PARAMETER
+
+class C {
+    fun f() {}
+}
+
+fun C.g(f: (String) -> Unit = { s -> f() }) {}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/invokeOnVariableWithExtensionFunctionType.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/invokeOnVariableWithExtensionFunctionType.fir.kt
new file mode 100644
index 00000000000..72dc0a20891
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/invokeOnVariableWithExtensionFunctionType.fir.kt
@@ -0,0 +1,84 @@
+// !WITH_NEW_INFERENCE
+// FILE: 1.kt
+package fooIsExtension
+
+class A
+class B
+
+val A.foo: B.() -> Unit get() = {}
+
+fun test(a: A, b: B) {
+    b.<!UNRESOLVED_REFERENCE!>(a.foo)()<!>
+    (a.foo)(b)
+    a.foo(b)
+
+    with(a) {
+        b.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+        b.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+
+        <!UNRESOLVED_REFERENCE!>(b.<!INAPPLICABLE_CANDIDATE!>foo<!>)()<!>
+
+        foo(b)
+        (foo)(b)
+    }
+
+    with(b) {
+        a.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+        a.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+
+        <!INAPPLICABLE_CANDIDATE!>(a.foo)()<!>
+
+        (a.foo)(this)
+        a.foo(this)
+    }
+
+    with(a) {
+        with(b) {
+            <!INAPPLICABLE_CANDIDATE!>foo<!>()
+            <!INAPPLICABLE_CANDIDATE!>(foo)()<!>
+        }
+    }
+}
+
+// FILE: 1.kt
+package fooIsMember
+
+class A {
+    val foo: B.() -> Unit get() = {}
+}
+class B
+
+fun test(a: A, b: B) {
+    b.<!UNRESOLVED_REFERENCE!>(a.foo)()<!>
+    (a.foo)(b)
+    a.foo(b)
+
+    with(a) {
+        b.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+        b.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+
+        <!UNRESOLVED_REFERENCE!>(b.<!UNRESOLVED_REFERENCE!>foo<!>)()<!>
+
+        foo(b)
+        (foo)(b)
+    }
+
+    with(b) {
+        a.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+        a.<!UNRESOLVED_REFERENCE!>(foo)()<!>
+
+        <!INAPPLICABLE_CANDIDATE!>(a.foo)()<!>
+
+        (a.foo)(this)
+        a.foo(this)
+    }
+
+    with(a) {
+        with(b) {
+            <!INAPPLICABLE_CANDIDATE!>foo<!>()
+            <!INAPPLICABLE_CANDIDATE!>(foo)()<!>
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/kt3772.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/kt3772.fir.kt
new file mode 100644
index 00000000000..5e9a39f6280
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/kt3772.fir.kt
@@ -0,0 +1,27 @@
+//KT-3772 Invoke and overload resolution ambiguity
+package bar
+
+open class A {
+    public operator fun invoke(f: A.() -> Unit) {}
+}
+
+class B {
+    public operator fun invoke(f: B.() -> Unit) {}
+}
+
+open class C
+val C.attr: A
+    get() = A()
+
+open class D: C()
+val D.attr: B
+    get() = B()
+
+
+fun main() {
+    val b =  D()
+    b.attr {} // overload resolution ambiguity
+
+    val d = b.attr
+    d {}      // no error
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/kt3833-invokeInsideNestedClass.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/kt3833-invokeInsideNestedClass.fir.kt
new file mode 100644
index 00000000000..fb4cdeecaa0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/kt3833-invokeInsideNestedClass.fir.kt
@@ -0,0 +1,35 @@
+//KT-3833 Invoke method not working inside companion object?
+package m
+
+class Either1 {
+    class Left() {
+        fun match(left: () -> Unit) {
+            left()
+        }
+    }
+
+    inner class Right() {
+        fun match(right: () -> Unit) {
+            right()
+        }
+    }
+}
+
+
+class X {
+    operator fun invoke() {
+    }
+}
+
+object Foo{
+    val v : X = X()
+}
+
+class C{
+    companion object {
+        fun f(){
+            Foo.v()
+        }
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/kt4204-completeNestedCallsForInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/kt4204-completeNestedCallsForInvoke.fir.kt
new file mode 100644
index 00000000000..874d9c980f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/kt4204-completeNestedCallsForInvoke.fir.kt
@@ -0,0 +1,24 @@
+//KT-4204 ConstraintSystem erased after resolution completion
+package c
+
+public abstract class TestBug1() {
+
+    public fun m3(position: Int) {
+        position(m1().second!!)
+    }
+
+    public fun m4(position: (Int)->Int) {
+        position(m1().second)
+    }
+
+    private abstract fun m1(): Pair<Int, Int>
+
+    private fun position(p: Int) {}
+
+}
+
+//from library
+public class Pair<out A, out B> (
+        public val first: A,
+        public val second: B
+)
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/kt4321InvokeOnEnum.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/kt4321InvokeOnEnum.fir.kt
new file mode 100644
index 00000000000..8080c3fec3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/kt4321InvokeOnEnum.fir.kt
@@ -0,0 +1,35 @@
+//KT-4321 invoke() on enum doesn't work
+
+import DOMElementTestClasses.cls2
+
+// use case 1
+enum class DOMElementTestClasses {
+    cls1, cls2;
+
+    operator fun invoke() {}
+}
+
+
+// use case 2
+interface EnumStyleClass {
+    operator fun invoke() {}
+}
+enum class TestClasses : EnumStyleClass {
+    cls
+}
+
+// example
+fun main() {
+    // Kotlin: Expression 'cls1' of type 'DOMElementTestClasses' cannot be invoked as a function
+    DOMElementTestClasses.cls1()
+
+    // Kotlin: Expression 'cls2' of type 'DOMElementTestClasses' cannot be invoked as a function
+    cls2()
+
+    // Kotlin: Expression 'cls' of type 'TestClasses' cannot be invoked as a function
+    TestClasses.cls()
+
+    // All ok
+    val cls = DOMElementTestClasses.cls2
+    cls()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/kt9517.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/kt9517.fir.kt
new file mode 100644
index 00000000000..8ec9a31cdf7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/kt9517.fir.kt
@@ -0,0 +1,16 @@
+
+//KT-9517 Wrong resolve for invoke convention after smart cast
+open class A {
+    open val foo: () -> Number = null!!
+}
+
+class B: A() {
+    override val foo: () -> Int
+        get() = null!!
+}
+
+fun test(a: A) {
+    if (a is B) {
+        val foo: Int = a.foo() // B::foo + invoke()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/kt9805.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/kt9805.fir.kt
new file mode 100644
index 00000000000..a0e0b9c1208
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/kt9805.fir.kt
@@ -0,0 +1,17 @@
+class A {
+    val foo: B.() -> Unit get() = null!!
+}
+
+class B
+
+fun test(a: A, b: B) {
+    with(b) {
+        a.<!INAPPLICABLE_CANDIDATE!>foo<!>() // here must be error, because a is not extension receiver
+
+        a.foo(this)
+
+        <!INAPPLICABLE_CANDIDATE!>(a.foo)()<!>
+
+        (a.foo)(this)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/reportFunctionExpectedWhenOneInvokeExist.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/reportFunctionExpectedWhenOneInvokeExist.fir.kt
new file mode 100644
index 00000000000..f71a3eceb98
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/reportFunctionExpectedWhenOneInvokeExist.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun Int.invoke() {}
+
+class SomeClass
+
+fun test(identifier: SomeClass, fn: String.() -> Unit) {
+    <!INAPPLICABLE_CANDIDATE!>identifier<!>()
+    <!INAPPLICABLE_CANDIDATE!>identifier<!>(123)
+    <!INAPPLICABLE_CANDIDATE!>identifier<!>(1, 2)
+    1.<!UNRESOLVED_REFERENCE!>fn<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/valNamedInvoke.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/valNamedInvoke.fir.kt
new file mode 100644
index 00000000000..2c8cfdd48bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/valNamedInvoke.fir.kt
@@ -0,0 +1,9 @@
+interface A
+
+fun foo(invoke: A.()->Unit, a: A) {
+    a.<!UNRESOLVED_REFERENCE!>invoke<!>()
+}
+
+fun bar(invoke: Any.()->Any, a: Any) {
+    a.<!UNRESOLVED_REFERENCE!>invoke<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/invoke/wrongInvokeExtension.fir.kt b/compiler/testData/diagnostics/tests/resolve/invoke/wrongInvokeExtension.fir.kt
new file mode 100644
index 00000000000..cce60dc62a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/invoke/wrongInvokeExtension.fir.kt
@@ -0,0 +1,18 @@
+class B
+
+class A {
+    operator fun B.invoke() {}
+}
+
+val B.a: () -> Int  get() = { 5 }
+
+fun test(a: A, b: B) {
+    val x: Int = b.a()
+
+    b.<!UNRESOLVED_REFERENCE!>(a)()<!>
+
+    with(b) {
+        val y: Int = <!UNRESOLVED_REFERENCE!>a<!>()
+        <!UNRESOLVED_REFERENCE!>(a)()<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/localObject.fir.kt b/compiler/testData/diagnostics/tests/resolve/localObject.fir.kt
new file mode 100644
index 00000000000..098f25c28e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/localObject.fir.kt
@@ -0,0 +1,4 @@
+fun foo(): Any {
+    object Bar
+    return Bar
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeArgsInFreeExpressionPosition.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeArgsInFreeExpressionPosition.fir.kt
new file mode 100644
index 00000000000..23ccbae857e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeArgsInFreeExpressionPosition.fir.kt
@@ -0,0 +1,12 @@
+class A {
+    companion object {
+
+    }
+}
+
+fun use(vararg a: Any?) = a
+
+fun test() {
+    use(use(A, null).toString())
+}
+
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeUnmappedArguments.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeUnmappedArguments.fir.kt
new file mode 100644
index 00000000000..f748d007e89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/analyzeUnmappedArguments.fir.kt
@@ -0,0 +1,9 @@
+package c
+
+fun test() {
+    with (1) l@ {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(1, zz = { this@l } )
+    }
+}
+
+fun foo(x: Int) = x
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.fir.kt
new file mode 100644
index 00000000000..1ffa3472243
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/argumentsInParentheses.fir.kt
@@ -0,0 +1,20 @@
+interface Foo<T>
+
+class Bar {
+    operator fun <T> invoke(): Foo<T> = throw Exception()
+}
+
+class A {
+    val bar = Bar()
+}
+
+fun fooInt(l: Foo<Int>) = l
+
+fun test(bar: Bar, a: A) {
+    // no elements with error types
+    fooInt((bar()))
+    fooInt(if (true) bar() else bar())
+    fooInt(label@ bar())
+    fooInt(a.bar())
+    fooInt(((label@ if (true) (a.bar()) else bar())))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/completeTypeInferenceForNestedInNoneApplicable.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/completeTypeInferenceForNestedInNoneApplicable.fir.kt
new file mode 100644
index 00000000000..08eb5f4d3ac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/completeTypeInferenceForNestedInNoneApplicable.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+package h
+
+fun foo(i: Int) = i
+fun foo(s: String) = s
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(emptyList())
+}
+
+fun <T> emptyList(): List<T> {throw Exception()}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/completeUnmappedArguments.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/completeUnmappedArguments.fir.kt
new file mode 100644
index 00000000000..7b787bf145c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/completeUnmappedArguments.fir.kt
@@ -0,0 +1,14 @@
+package c
+
+fun zzz(i: Int, f: (Int) -> Int) { throw Exception("$i $f")}
+
+fun test() {
+    fun foo(): Int = 42
+
+    fun bar(i: Int) = i
+
+    bar(<!INAPPLICABLE_CANDIDATE!>foo<!>(xx = zzz(11) { j: Int -> j + 7 }))
+
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(zz = <!INAPPLICABLE_CANDIDATE!>foo<!>(
+      xx = zzz(12) { i: Int -> i + i }))
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/kt5971NestedSafeCall.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/kt5971NestedSafeCall.fir.kt
new file mode 100644
index 00000000000..48e34c01f67
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/kt5971NestedSafeCall.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+//KT-5971 Missing error when fun argument is safe call
+
+fun foo(i: Int) {}
+
+fun test(s: String?) {
+    foo(s?.length)
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/kt7597.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/kt7597.fir.kt
new file mode 100644
index 00000000000..9e8cb9218b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/kt7597.fir.kt
@@ -0,0 +1,8 @@
+interface Inv<I>
+
+fun <S, T: S> Inv<T>.reduce2(): S = null!!
+
+fun test(a: Inv<Int>): Int {
+    val b = 1 + a.reduce2()
+    return b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/manyInapplicableCandidatesWithLambdas.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/manyInapplicableCandidatesWithLambdas.fir.kt
new file mode 100644
index 00000000000..f0b8c73eac2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/manyInapplicableCandidatesWithLambdas.fir.kt
@@ -0,0 +1,53 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A
+class B
+class C
+class D
+
+fun A.bar(x: Int = 0) = ""
+fun A.bar(x: Int = 0, y: D.() -> Unit) = ""
+
+fun B.bar(x: Int = 0) = ""
+fun B.bar(x: Int = 0, y: D.() -> Unit) = ""
+
+fun C.bar(x: Int = 0) = ""
+fun C.bar(x: Int = 0, y: D.() -> Unit) = ""
+
+class E {
+    fun foo() {
+        // `bar` calls are inapplicable since both E nor D aren't proper receivers
+        // But prior to this change, every lambda was analyzed repeatedly for every candidate
+        // Thus, the resulting time was exponential
+        <!INAPPLICABLE_CANDIDATE!>bar<!> {
+            <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                    <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                        <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                            <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                    <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                        <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                            <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                                <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                                    <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                                        <!INAPPLICABLE_CANDIDATE!>bar<!> {
+                                                            <!INAPPLICABLE_CANDIDATE!>bar<!> {
+
+                                                            }
+                                                        }
+                                                    }
+                                                }
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/resolve/nestedCalls/twoTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/resolve/nestedCalls/twoTypeParameters.fir.kt
new file mode 100644
index 00000000000..d7b16cc0eb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/nestedCalls/twoTypeParameters.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+class ResolutionCandidate<A>
+
+class ResolutionTask<B, C : B>(val candidate: ResolutionCandidate<B>)
+
+fun <D, E : D> List<ResolutionTask<D, E>>.bar(t: ResolutionTask<D, E>) = t
+
+public class ResolutionTaskHolder<F, G : F> {
+    fun test(candidate: ResolutionCandidate<F>, tasks: MutableList<ResolutionTask<F, G>>) {
+        tasks.bar(ResolutionTask<F, G>(candidate))
+        tasks.add(ResolutionTask<F, G>(candidate))
+
+        //todo the problem is the type of ResolutionTask is inferred as ResolutionTask<F, F> too early
+        tasks.bar(ResolutionTask(candidate))
+        tasks.add(ResolutionTask(candidate))
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/newLineLambda.fir.kt b/compiler/testData/diagnostics/tests/resolve/newLineLambda.fir.kt
new file mode 100644
index 00000000000..3646efb9384
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/newLineLambda.fir.kt
@@ -0,0 +1,118 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun noArgs() {}
+fun oneLambdaArg(fn: () -> Unit) {}
+fun twoLambdaArgs(f1: () -> Unit, f2: () -> Unit) {}
+fun varargFn(vararg args: Int) {}
+
+fun testNoArgs() {
+    noArgs()
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!> {}
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!>() {}
+    noArgs() // {}
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!>() /* */ {}
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!>() /*
+        block comment, no new line
+    */ {}
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!>()
+    /*
+        block comment with new line
+    */
+    {}
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!>() // comment
+    // comment
+    {}
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!>() {} {}
+    <!INAPPLICABLE_CANDIDATE!>noArgs<!>() {}
+    {}
+}
+
+fun testLambdaArg() {
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>()
+    oneLambdaArg {}
+    oneLambdaArg()
+    {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>()
+    {}
+    {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>(
+        {},
+        {}
+    )
+    oneLambdaArg() {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>() // {}
+    oneLambdaArg() /* */ {}
+    oneLambdaArg() /*
+        block
+        comment
+    */ {}
+    oneLambdaArg() // comment
+    // comment
+    {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>() {}/*
+        block comment, no new line
+    */ {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>() {}/*
+        block comment with new line
+    */
+    {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>() {}// comment
+    // comment
+    {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>() {} {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>() {}
+    {}
+    <!INAPPLICABLE_CANDIDATE!>oneLambdaArg<!>() {} // comment
+    {}
+}
+
+fun testVararg() {
+    varargFn(1,2,3)
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!> {}
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) {}
+    varargFn(1,2,3) // {}
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) /* */ {}
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) /*
+        block comment, no new line
+    */ {}
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3)
+    /*
+        block comment with new line
+    */ {}
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) // comment
+    // comment
+    {}
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) {} {}
+    <!INAPPLICABLE_CANDIDATE!>varargFn<!>(1,2,3) {}
+    {}
+}
+
+fun testTwoLambdas() {
+    twoLambdaArgs(
+        f1 = {},
+        f2 =
+        {}
+    )
+
+    fun bar(): () -> Unit {
+        <!INAPPLICABLE_CANDIDATE!>twoLambdaArgs<!>()
+        {}
+        {}
+
+        return if (true) {
+            <!INAPPLICABLE_CANDIDATE!>twoLambdaArgs<!>({})
+            {}
+            {}
+        } else {
+            {}
+        }
+    }
+}
+
+fun f1(): (() -> Unit) -> (() -> Unit) -> Unit {
+    return { l1 ->
+        <!INAPPLICABLE_CANDIDATE!>l1<!>()
+        { l2 -> <!UNRESOLVED_REFERENCE!>l2<!>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/noCandidates/kt2787.fir.kt b/compiler/testData/diagnostics/tests/resolve/noCandidates/kt2787.fir.kt
new file mode 100644
index 00000000000..f884ab6fea4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/noCandidates/kt2787.fir.kt
@@ -0,0 +1,6 @@
+interface MutableMatrix<T> {
+}
+
+fun <T> toMutableMatrix(): MutableMatrix<T> {
+    return <!UNRESOLVED_REFERENCE!>MutableMatrix<!><T>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/noCandidates/resolvedToClassifier.fir.kt b/compiler/testData/diagnostics/tests/resolve/noCandidates/resolvedToClassifier.fir.kt
new file mode 100644
index 00000000000..373bd9da30e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/noCandidates/resolvedToClassifier.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+interface A
+
+object B
+class C
+
+fun test() {
+    val interface_as_fun = <!UNRESOLVED_REFERENCE!>A<!>()
+    val interface_as_val = A
+
+    val object_as_fun = <!INAPPLICABLE_CANDIDATE!>B<!>()
+    val class_as_val = C
+}
+
+fun <T> bar() {
+    val typeParameter_as_val = <!OTHER_ERROR, OTHER_ERROR!>T<!>
+    val typeParameter_as_fun = <!UNRESOLVED_REFERENCE!>T<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/noCandidates/resolvedToClassifierWithReceiver.fir.kt b/compiler/testData/diagnostics/tests/resolve/noCandidates/resolvedToClassifierWithReceiver.fir.kt
new file mode 100644
index 00000000000..d5a24a8d485
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/noCandidates/resolvedToClassifierWithReceiver.fir.kt
@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+object X {
+    interface A
+
+    object B
+    class C
+}
+
+fun testX() {
+    val interface_as_fun = X.<!UNRESOLVED_REFERENCE!>A<!>()
+    val interface_as_val = X.A
+
+    val object_as_fun = X.<!INAPPLICABLE_CANDIDATE!>B<!>()
+    val class_as_val = X.C
+}
+
+class Y {
+    interface A
+
+    object B
+    class C
+}
+
+fun testY() {
+    val interface_as_fun = Y.<!UNRESOLVED_REFERENCE!>A<!>()
+    val interface_as_val = Y.A
+
+    val object_as_fun = Y.<!INAPPLICABLE_CANDIDATE!>B<!>()
+    val class_as_val = Y.C
+}
+
+fun test(x: X) {
+    val interface_as_fun = x.<!UNRESOLVED_REFERENCE!>A<!>()
+    val interface_as_val = x.A
+
+    val object_as_fun = x.<!INAPPLICABLE_CANDIDATE!>B<!>()
+    val class_as_val = x.C
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/objectLiteralAsArgument.fir.kt b/compiler/testData/diagnostics/tests/resolve/objectLiteralAsArgument.fir.kt
new file mode 100644
index 00000000000..9cae82ca8a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/objectLiteralAsArgument.fir.kt
@@ -0,0 +1,36 @@
+//If this test hangs, it means something is broken.
+object A {
+    val iii = 42
+}
+
+//inappropriate but participating in resolve functions
+fun foo(s: String, a: Any) = s + a
+
+fun foo(a: Any, s: String) = s + a
+fun foo(i: Int, j: Int) = i + j
+fun foo(a: Any, i: Int) = "$a$i"
+fun foo(f: (Int) -> Int, i: Int) = f(i)
+fun foo(f: (String) -> Int, s: String) = f(s)
+fun foo(f: (Any) -> Int, a: Any) = f(a)
+fun foo(s: String, f: (String) -> Int) = f(s)
+fun foo(a: Any, f: (Any) -> Int) = f(a)
+//appropriate function
+fun foo(i: Int, f: (Int) -> Int) = f(i)
+
+fun test() {
+    foo(1, object : (Int) -> Int {
+        override fun invoke(x1: Int) = foo(
+                2, object : (Int) -> Int {
+            override fun invoke(x2: Int) = foo(
+                    3, object : (Int) -> Int {
+                override fun invoke(x3: Int): Int = foo(
+                        4, object : (Int) -> Int {
+                    override fun invoke(x4: Int): Int = foo(
+                            5, object : (Int) -> Int {
+                        override fun invoke(x5: Int): Int = x1 + x2 + x3 + x4 + x5 + A.iii
+                    })
+                })
+            })
+        })
+    })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/allLambdas.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/allLambdas.fir.kt
new file mode 100644
index 00000000000..b85b6f1d582
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/allLambdas.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object X1
+object X2
+
+fun <T1> foo(x: T1, f: (T1) -> T1) = X1
+fun <T2> foo(xf: () -> T2, f: (T2) -> T2) = X2
+
+val test: X2 = <!AMBIGUITY!>foo<!>({ 0 }, { it -> it + 1 })
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/extensionReceiverAndVarargs.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/extensionReceiverAndVarargs.fir.kt
new file mode 100644
index 00000000000..ef9bf7b8da9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/extensionReceiverAndVarargs.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Right
+object Wrong
+
+interface IA
+interface IB : IA
+fun IA.foo(vararg x: Int) = Wrong
+fun IB.foo(vararg x: Int) = Right
+class CC : IB
+
+val test7 = CC().foo(1, 2, 3)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/genericClash.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/genericClash.fir.kt
new file mode 100644
index 00000000000..20d555ddddc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/genericClash.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+interface A<T> {
+    fun foo(x: T)
+    fun foo(x: String)
+
+    fun <E> baz(x: E, y: String)
+    fun <E> baz(x: String, y: E)
+}
+
+fun <E> baz(x: E, y: String) {}
+fun <E> baz(x: String, y: E) {}
+
+fun bar(x: A<String>) {
+    x.<!AMBIGUITY!>foo<!>("")
+
+    x.<!AMBIGUITY!>baz<!>("", "")
+    <!AMBIGUITY!>baz<!>("", "")
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/genericWithProjection.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/genericWithProjection.fir.kt
new file mode 100644
index 00000000000..0d0742be152
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/genericWithProjection.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -REDUNDANT_PROJECTION
+
+class In<in T>() {
+    fun f(t : T) {}
+    fun f(t : Int) = t
+}
+
+fun test1(x: In<String>): Unit = x.f("1")
+fun test2(x: In<in String>): Unit = x.f("1")
+fun test3(x: In<out String>): Unit = x.f("1")
+fun test4(x: In<*>): Unit = x.f("1")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt10472.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt10472.fir.kt
new file mode 100644
index 00000000000..62c58aaf588
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt10472.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Right
+object Wrong
+
+interface A<T>
+interface B<T> : A<T>
+
+fun <T> foo(vararg t: T) = Wrong
+fun <T> foo(t: A<T>) = Wrong
+fun <T> foo(t: B<T>) = Right
+
+fun test(b: B<Int>): Right = foo(b)
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt10640.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt10640.fir.kt
new file mode 100644
index 00000000000..1fd5e880bc4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt10640.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+interface AutoCloseable
+interface Closeable : AutoCloseable
+
+fun <T1 : AutoCloseable, R1> T1.myUse(f: (T1) -> R1): R1 = f(this)
+fun <T2 : Closeable, R2> T2.myUse(f: (T2) -> R2): R2 = f(this)
+
+fun test1(x: Closeable) = x.myUse { 42 }
+fun test2(x: Closeable) = x.myUse<Closeable, Int> { 42 }
+fun test3(x: Closeable) = x.myUse<AutoCloseable, Int> { 42 } // TODO KT-10681
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31670.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31670.fir.kt
new file mode 100644
index 00000000000..6a5f32372ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31670.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !CONSTRAINT_SYSTEM_FOR_OVERLOAD_RESOLUTION: CONSTRAINT_SYSTEM_FOR_NEW_INFERENCE
+
+open class A<T>(val value: T)
+class B<T>(value: T) : A<T>(value)
+
+fun <T> A<T>.foo(block: (T?) -> Unit) {
+    block(value)
+}
+fun <T> B<T>.foo(block: (T) -> Unit) {
+    block(value)
+}
+
+fun main() {
+    B("string").<!AMBIGUITY!>foo<!> {  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31670_compat.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31670_compat.fir.kt
new file mode 100644
index 00000000000..021ff3cea73
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31670_compat.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// !CONSTRAINT_SYSTEM_FOR_OVERLOAD_RESOLUTION: CONSTRAINT_SYSTEM_FOR_OLD_INFERENCE
+
+open class A<T>(val value: T)
+class B<T>(value: T) : A<T>(value)
+
+fun <T> A<T>.foo(block: (T?) -> Unit) {
+    block(value)
+}
+fun <T> B<T>.foo(block: (T) -> Unit) {
+    block(value)
+}
+
+fun main() {
+    B("string").<!AMBIGUITY!>foo<!> {  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31758.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31758.fir.kt
new file mode 100644
index 00000000000..3a67bfa5323
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31758.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// !CONSTRAINT_SYSTEM_FOR_OVERLOAD_RESOLUTION: CONSTRAINT_SYSTEM_FOR_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: a.kt
+
+package a
+
+enum class A { A1 }
+
+fun <T : Enum<T>> foo(arg: T.() -> Unit) = 1
+
+// FILE: b.kt
+
+package b
+
+fun <T : Any> foo(arg: T.() -> Unit) = 2
+
+// FILE: test.kt
+
+import a.*
+import b.*
+
+fun test() {
+    <!AMBIGUITY!>foo<!><A> { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31758_compat.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31758_compat.fir.kt
new file mode 100644
index 00000000000..69fa18f44ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/kt31758_compat.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+// !CONSTRAINT_SYSTEM_FOR_OVERLOAD_RESOLUTION: CONSTRAINT_SYSTEM_FOR_OLD_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: a.kt
+
+package a
+
+enum class A { A1 }
+
+fun <T : Enum<T>> foo(arg: T.() -> Unit) = 1
+
+// FILE: b.kt
+
+package b
+
+fun <T : Any> foo(arg: T.() -> Unit) = 2
+
+// FILE: test.kt
+
+import a.*
+import b.*
+
+fun test() {
+    <!AMBIGUITY!>foo<!><A> { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/numberOfDefaults.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/numberOfDefaults.fir.kt
new file mode 100644
index 00000000000..794be2d88fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/numberOfDefaults.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Right
+object Wrong
+
+fun overloadedFun(c: Any = "", b: String = "", f: Any = "") = Right
+fun overloadedFun(b: Any = "", c: Any = "", e: String = "", x: String = "", y: String = "") = Wrong
+
+val test: Right = overloadedFun(b = "")
+
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/originalExamples.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/originalExamples.fir.kt
new file mode 100644
index 00000000000..63f59b6fc34
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/originalExamples.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Right
+object Wrong
+
+fun overloadedFun1(c: Any = "", b: String = "", f: Any = "") = Right
+fun overloadedFun1(b: Any = "", c: Any = "", e: String = "") = Wrong
+
+val test1: Right = overloadedFun1(b = "")
+val test1a: Wrong = overloadedFun1(b = "")
+
+fun overloadedFun2(a: String, b: Any = "") = Right
+fun overloadedFun2(a: Any, b: String = "") = Wrong
+
+val test2: Right = overloadedFun2("")
+
+fun overloadedFun2a(a: Any, b: String = "") = Wrong
+fun overloadedFun2a(a: String, b: Any = "") = Right
+
+val test2a: Right = overloadedFun2a("")
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/overloadResolutionOnNullableContravariantParameter.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/overloadResolutionOnNullableContravariantParameter.fir.kt
new file mode 100644
index 00000000000..dbbc7e4e962
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/overloadResolutionOnNullableContravariantParameter.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !CONSTRAINT_SYSTEM_FOR_OVERLOAD_RESOLUTION: CONSTRAINT_SYSTEM_FOR_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: a.kt
+
+package a
+
+fun <T> foo(block: (T?) -> Unit) {}
+
+// FILE: b.kt
+
+package b
+
+fun <K> foo(block: (K) -> Unit) {}
+
+// FILE: test.kt
+
+import a.*
+import b.*
+
+fun main() {
+    foo<String> {  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/overloadResolutionOnNullableContravariantParameter_compat.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/overloadResolutionOnNullableContravariantParameter_compat.fir.kt
new file mode 100644
index 00000000000..ef9e1f8de6e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/overloadResolutionOnNullableContravariantParameter_compat.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !CONSTRAINT_SYSTEM_FOR_OVERLOAD_RESOLUTION: CONSTRAINT_SYSTEM_FOR_OLD_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: a.kt
+
+package a
+
+fun <T> foo(block: (T?) -> Unit) {}
+
+// FILE: b.kt
+
+package b
+
+fun <K> foo(block: (K) -> Unit) {}
+
+// FILE: test.kt
+
+import a.*
+import b.*
+
+fun main() {
+    foo<String> {  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargWithMoreSpecificSignature.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargWithMoreSpecificSignature.fir.kt
new file mode 100644
index 00000000000..67aa60f2c80
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargWithMoreSpecificSignature.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Foo1
+object Foo2
+
+fun foo(vararg ss: String) = Foo1
+fun foo(x: Any) = Foo2
+
+val test1: Foo1 = foo("")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargs.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargs.fir.kt
new file mode 100644
index 00000000000..3991c9e26d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargs.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object Right
+object Wrong
+
+fun overloadedFun6(s1: String) = Right
+fun overloadedFun6(s1: String, s2: String) = Wrong
+fun overloadedFun6(s1: String, s2: String, s3: String) = Wrong
+fun overloadedFun6(s: String, vararg ss: String) = Wrong
+
+val test6: Right = overloadedFun6("")
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsInDifferentPositions.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsInDifferentPositions.fir.kt
new file mode 100644
index 00000000000..ba34c23519c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsInDifferentPositions.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +ProhibitAssigningSingleElementsToVarargsInNamedForm
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object X1
+object X2
+
+fun overloadedFun(arg: String, vararg args: String) = X1
+fun overloadedFun(arg: String, vararg args: String, flag: Boolean = true) = X2
+
+val test1a: X1 = overloadedFun("", "")
+val test1b: X1 = overloadedFun("", args = "")
+val test1c: X2 = overloadedFun("", "", "", flag = true)
+
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsMixed.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsMixed.fir.kt
new file mode 100644
index 00000000000..240eac7e794
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsMixed.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +ProhibitAssigningSingleElementsToVarargsInNamedForm
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+object X1
+object X2
+
+fun overloadedFun5(vararg ss: String) = X1
+fun overloadedFun5(s: String, vararg ss: String) = X2
+
+val test1 = overloadedFun5("")
+val test2 = overloadedFun5("", "")
+val test3: X2 = overloadedFun5(s = "", ss = "")
+val test4: X1 = overloadedFun5(ss = "")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsWithRecursiveGenerics.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsWithRecursiveGenerics.fir.kt
new file mode 100644
index 00000000000..8414bfee2b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/varargsWithRecursiveGenerics.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: J.java
+import java.util.*;
+
+public class J {
+    public static <E1 extends Enum<E1>> String foo(E1 e) { return ""; }
+    public static <E2 extends Enum<E2>> String foo(E2 e1, E2 e2) { return ""; }
+    public static <E3 extends Enum<E3>> String foo(E3 s1, E3 s2, E3 s3) { return ""; }
+    public static <E4 extends Enum<E4>> int foo(E4... ss) { return 0; }
+}
+
+// FILE: test.kt
+enum class X { A }
+val a = X.A
+
+val test0: Int = J.foo<X>()
+val test1: String = J.foo(a)
+val test2: String = J.foo(a, a)
+val test3: String = J.foo(a, a, a)
+val test4: Int = J.foo(a, a, a, a)
+val test5: Int = J.foo(a, a, a, a, a)
diff --git a/compiler/testData/diagnostics/tests/resolve/overloadConflicts/withVariance.fir.kt b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/withVariance.fir.kt
new file mode 100644
index 00000000000..a0203b1cbcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/overloadConflicts/withVariance.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+object X1
+object X2
+
+class A<T>
+
+fun <T1> A<T1>.foo() = X1
+fun <T2> A<out T2>.foo() = X2
+
+fun <T> A<out T>.test() = foo() // TODO fix constraint system
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/parameterAsDefaultValueInLocalFunction.fir.kt b/compiler/testData/diagnostics/tests/resolve/parameterAsDefaultValueInLocalFunction.fir.kt
new file mode 100644
index 00000000000..b0180e74966
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/parameterAsDefaultValueInLocalFunction.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo() {
+    fun bar(x: String, y: String = x) {}
+    fun baz(x: Int = <!UNRESOLVED_REFERENCE!>y<!>, y: Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/invokeExtensionVsOther.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/invokeExtensionVsOther.fir.kt
new file mode 100644
index 00000000000..e92ef718eaf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/invokeExtensionVsOther.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class A
+
+class B {
+    fun foo() = this
+}
+
+fun test(foo: A.() -> Int) {
+    with(A()) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!INAPPLICABLE_CANDIDATE!>_<!><Int>() }
+        with(B()) {
+            foo() checkType { _<B>() }
+            this.foo() checkType { _<B>() }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/invokeExtensionVsOther2.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/invokeExtensionVsOther2.fir.kt
new file mode 100644
index 00000000000..ac7e7458842
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/invokeExtensionVsOther2.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class A {
+    fun foo() = this
+}
+
+fun test(foo: A.() -> Int) {
+    with(A()) {
+        foo() checkType { _<A>() }
+        this.foo() checkType { _<A>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/kt10219.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/kt10219.fir.kt
new file mode 100644
index 00000000000..ec8217ed65a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/kt10219.fir.kt
@@ -0,0 +1,22 @@
+// FILE: Calendar.java
+public class Calendar {
+    public void setTimeInMillis(long millis) {}
+    public long getTimeInMillis() { return 1; }
+}
+
+// FILE: 1.kt
+class A
+
+var A.timeInMillis: String
+    get() = ""
+    set(v) {}
+
+fun a(c: Calendar) {
+    A().apply {
+        c.apply {
+            timeInMillis = 5 // synthesized variable for get|setTimeInMillis
+            timeInMillis = ""
+        }
+        timeInMillis = ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/kt10510.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/kt10510.fir.kt
new file mode 100644
index 00000000000..383c6940e68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/kt10510.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class ClassA {
+    fun method1() = this
+
+    fun String.method2() {
+        method1() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+        this.method1() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+    }
+}
+
+fun String.method1() = this
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/kt9810.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/kt9810.fir.kt
new file mode 100644
index 00000000000..db63cc5e5bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/kt9810.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+// KT-9810 Local variable vs property from implicit receiver
+
+class A {
+    val foo = 2
+}
+
+fun test(foo: String) {
+    with(A()) {
+        val g: String = foo // locals win
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/kt9965.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/kt9965.fir.kt
new file mode 100644
index 00000000000..0be29b963af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/kt9965.fir.kt
@@ -0,0 +1,20 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+enum class Foo {
+    FOO;
+
+    companion object {
+        fun valueOf(something: String) = 2
+
+        fun values() = 1
+    }
+}
+
+fun test() {
+    Foo.values() checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<Foo>>() }
+    Foo.Companion.values() checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    Foo.valueOf("") checkType { <!UNRESOLVED_REFERENCE!>_<!><Foo>() }
+    Foo.Companion.valueOf("") checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/localExtVsNonLocalExt.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/localExtVsNonLocalExt.fir.kt
new file mode 100644
index 00000000000..f268f5f6600
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/localExtVsNonLocalExt.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+
+class A
+
+fun A.foo() = this
+
+fun test(a: A) {
+    fun A.foo() = 3
+
+    a.foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    with(a) {
+        foo() checkType { _<Int>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/memberVsLocalExt.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/memberVsLocalExt.fir.kt
new file mode 100644
index 00000000000..1bd8872c5b0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/memberVsLocalExt.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+class A {
+    fun foo() = this
+}
+
+
+fun test(a: A) {
+    fun A.foo() = 4
+
+    a.foo() checkType { <!UNRESOLVED_REFERENCE!>_<!><A>() }
+
+    with(a) {
+        foo() checkType { _<A>() }
+        this.foo() checkType { _<A>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/staticVsImplicitReceiverMember.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/staticVsImplicitReceiverMember.fir.kt
new file mode 100644
index 00000000000..959f6d53415
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/staticVsImplicitReceiverMember.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: A.java
+public class A {
+    public static void foo() {}
+}
+
+// FILE: 1.kt
+
+class C {
+    fun foo() = this
+
+    inner class B : A() {
+        fun test() {
+            foo() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Unit>() }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/synthesizedMembersVsExtension.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/synthesizedMembersVsExtension.fir.kt
new file mode 100644
index 00000000000..1e7e5cd98fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/synthesizedMembersVsExtension.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+data class A(val foo: Int)
+
+operator fun A.component1(): String = ""
+
+fun test(a: A) {
+    val (b) = a
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/syntheticPropertiesVsExtensions.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/syntheticPropertiesVsExtensions.fir.kt
new file mode 100644
index 00000000000..4ef52eb8488
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/syntheticPropertiesVsExtensions.fir.kt
@@ -0,0 +1,29 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: A.java
+public class A {
+    public A getFoo() { return 3; }
+}
+
+// FILE: 1.kt
+
+private val A.foo: Int get() = 4
+
+fun test(a: A) {
+    a.foo checkType { <!UNRESOLVED_REFERENCE!>_<!><A>() }
+    with(a) {
+        foo checkType { _<A>() }
+    }
+}
+
+class B {
+    private val A.foo: B get() = this@B
+
+    fun test(a: A) {
+        a.foo checkType { <!INAPPLICABLE_CANDIDATE!>_<!><A>() }
+        with(a) {
+            foo checkType { _<A>() }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/priority/syntheticPropertiesVsMembers.fir.kt b/compiler/testData/diagnostics/tests/resolve/priority/syntheticPropertiesVsMembers.fir.kt
new file mode 100644
index 00000000000..83c50b4bd1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/priority/syntheticPropertiesVsMembers.fir.kt
@@ -0,0 +1,36 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: A.java
+public class A {
+    public A getFoo() { return 3; }
+}
+
+// FILE: B.java
+public class B {
+    public B getFoo() { return ""; }
+}
+
+// FILE: 1.kt
+class C(val foo: C)
+
+fun test(a: A, b: B, c: C) {
+    with(a) {
+        with(b) {
+            foo checkType { _<B>() }
+        }
+        foo checkType { _<A>() }
+    }
+
+    with(a) {
+        with(c) {
+            foo checkType { _<C>() }
+        }
+    }
+
+    with(c) {
+        with(a) {
+            foo checkType { _<A>() }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveAnnotatedLambdaArgument.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveAnnotatedLambdaArgument.fir.kt
new file mode 100644
index 00000000000..02d00521086
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveAnnotatedLambdaArgument.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Ann
+
+fun <T> bar(block: (T) -> Int) {}
+
+fun foo() {
+    bar<Int> @Ann @[Ann] { x -> x }
+    bar<Int> @Ann @[Ann] label@{ x -> x }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveTypeArgsForUnresolvedCall.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveTypeArgsForUnresolvedCall.fir.kt
new file mode 100644
index 00000000000..6baf4a9ebe5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveTypeArgsForUnresolvedCall.fir.kt
@@ -0,0 +1,4 @@
+fun foo() {
+    <!UNRESOLVED_REFERENCE!>x<!>.<!UNRESOLVED_REFERENCE!>yyy<!><XXX>()
+    <!UNRESOLVED_REFERENCE!>x<!>.<!UNRESOLVED_REFERENCE!>yyy<!><Int>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiteralWithId.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiteralWithId.fir.kt
new file mode 100644
index 00000000000..cf4402b7539
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiteralWithId.fir.kt
@@ -0,0 +1,32 @@
+//If this test hangs, it means something is broken.
+object A {
+    val iii = 42
+}
+
+//inappropriate but participating in resolve functions
+fun foo(s: String, a: Any) = s + a
+fun foo(a: Any) = a
+fun foo(i: Int) = i
+fun foo(a: Any, i: Int, f: ()-> Int) = "$a$i${f()}"
+fun foo(f: (Int)->Int, i: Int) = f(i)
+fun foo(f: (String)->Int, s: String) = f(s)
+fun foo(f: (Any)->Int, a: Any) = f(a)
+fun foo(s: String, f: (String, String)->Int) = f(s, s)
+//appropriate function
+fun foo(i: Int, f: (Int)->Int) = f(i)
+
+fun <T> id(t: T) = t
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(1, id { x1 ->
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(2, id { x2 ->
+            <!INAPPLICABLE_CANDIDATE!>foo<!>(3, id { x3 ->
+                <!INAPPLICABLE_CANDIDATE!>foo<!>(4, id { x4 ->
+                    <!INAPPLICABLE_CANDIDATE!>foo<!>(5, id { x5 ->
+                        x1 + x2 + x3 + x4 + x5 + A.iii
+                    })
+                })
+            })
+        })
+    })
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiterals.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiterals.fir.kt
new file mode 100644
index 00000000000..514962d5bc0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiterals.fir.kt
@@ -0,0 +1,30 @@
+object A {
+    val iii = 42
+}
+
+//inappropriate but participating in resolve functions
+//fun foo(s: String, a: Any) = s + a
+//fun foo(a: Any, s: String) = s + a
+//fun foo(i: Int, j: Int) = i + j
+//fun foo(a: Any, i: Int) = "$a$i"
+//fun foo(f: (Int)->Int, i: Int) = f(i)
+//fun foo(f: (String)->Int, s: String) = f(s)
+//fun foo(f: (Any)->Int, a: Any) = f(a)
+//fun foo(s: String, f: (String)->Int) = f(s)
+//fun foo(a: Any, f: (Any)->Int) = f(a)
+//appropriate function
+fun foo(i: Int, f: (Int)->Int) = f(i)
+
+fun test() {
+    foo(1) { x1: Int ->
+        foo(2) { x2: Int ->
+            foo(3) { x3: Int ->
+                foo(4) { x4: Int ->
+                    foo(5) { x5: Int ->
+                        x1 + x2 + x3 + x4 + x5 + A.iii
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiteralsOverload.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiteralsOverload.fir.kt
new file mode 100644
index 00000000000..7b6e982c94d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveWithFunctionLiteralsOverload.fir.kt
@@ -0,0 +1,31 @@
+//If this test hangs, it means something is broken.
+object A {
+    val iii = 42
+}
+
+//inappropriate but participating in resolve functions
+fun foo(s: String, a: Any) = s + a
+fun foo(a: Any, s: String) = s + a
+fun foo(i: Int, j: Int) = i + j
+fun foo(a: Any, i: Int) = "$a$i"
+fun foo(f: (Int)->Int, i: Int) = f(i)
+fun foo(f: (String)->Int, s: String) = f(s)
+fun foo(f: (Any)->Int, a: Any) = f(a)
+fun foo(s: String, f: (String)->Int) = f(s)
+fun foo(a: Any, f: (Any)->Int) = f(a)
+//appropriate function
+fun foo(i: Int, f: (Int)->Int) = f(i)
+
+fun test() {
+    foo(1) { x1: Int ->
+        foo(2) { x2: Int ->
+            foo(3) { x3: Int ->
+                foo(4) { x4: Int ->
+                    foo(5) { x5: Int ->
+                        x1 + x2 + x3 + x4 + x5 + A.iii
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveWithGenerics.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveWithGenerics.fir.kt
new file mode 100644
index 00000000000..d77aed83c16
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveWithGenerics.fir.kt
@@ -0,0 +1,21 @@
+//If this test hangs, it means something is broken.
+package a
+
+class A {
+    val testVal : A = A()
+}
+
+//inappropriate but participating in resolve functions
+fun <T> foo(a: T, b: T, i: Int) = a
+fun foo(a: Any) = a
+fun <T> foo(a: T, b: String) = a
+fun <T> foo(a: T, b: T, s: String) = a
+//appropriate function
+fun <T> foo(a: T, b: T) = a
+
+fun test(a: A) {
+    //the problem occurs if there are nested function invocations to resolve (resolve for them is repeated now)
+    //to copy this invocation many times (and to comment/uncomment inappropriate functions) to see the difference
+    foo(foo(a, foo(a, foo(a, a.testVal))), a)
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveWithRedeclarationError.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveWithRedeclarationError.fir.kt
new file mode 100644
index 00000000000..e44a56bef9b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveWithRedeclarationError.fir.kt
@@ -0,0 +1,34 @@
+//If this test hangs, it means something is broken.
+package c
+
+fun z(view: () -> Unit) {}
+
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+fun x() = z { z { z { z { z { z { z { z { } } } } } } } }
+
+class x() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveWithSpecifiedFunctionLiteralWithId.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveWithSpecifiedFunctionLiteralWithId.fir.kt
new file mode 100644
index 00000000000..67b4400b312
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveWithSpecifiedFunctionLiteralWithId.fir.kt
@@ -0,0 +1,36 @@
+// !WITH_NEW_INFERENCE
+//If this test hangs, it means something is broken.
+package a
+
+object A {
+    val iii = 42
+}
+
+//inappropriate but participating in resolve functions
+fun foo(s: String, a: Any) = s + a
+fun foo(a: Any, s: String) = s + a
+fun foo(i: Int, j: Int) = i + j
+fun foo(a: Any, i: Int) = "$a$i"
+fun foo(f: (Int) -> Int, i: Int) = f(i)
+fun foo(f: (String) -> Int, s: String) = f(s)
+fun foo(f: (Any) -> Int, a: Any) = f(a)
+fun foo(s: String, f: (String) -> Int) = f(s)
+fun foo(a: Any, f: (Any) -> Int) = f(a)
+//appropriate function
+fun foo(i: Int, f: (Int) -> Int) = f(i)
+
+fun <T> id(t: T) = t
+
+fun test() {
+    foo(1, id(fun(x1: Int) =
+          foo(2, id(fun(x2: Int) =
+                foo(3, id(fun(x3: Int) =
+                      foo(4, id(fun(x4: Int) =
+                            foo(5, id(fun(x5: Int) =
+                                  x1 + x2 + x3 + x4 + x5 + A.iii
+                            ))
+                      ))
+                ))
+          ))
+    ))
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/resolveWithoutGenerics.fir.kt b/compiler/testData/diagnostics/tests/resolve/resolveWithoutGenerics.fir.kt
new file mode 100644
index 00000000000..89fed6051f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/resolveWithoutGenerics.fir.kt
@@ -0,0 +1,20 @@
+//If this test hangs, it means something is broken.
+package c
+
+class A {
+    val testVal : A = A()
+}
+
+//inappropriate but participating in resolve functions
+fun foo(a: A, b: A, i: Int) = a
+fun foo(a: Any) = a
+fun foo(a: A, b: Any) = a
+fun foo(a: A, b: A, s: String) = a
+//appropriate function
+fun foo(a: A, b: A) = a
+
+fun test(a: A) {
+    //the problem occurs if there are nested function invocations to resolve (resolve for them is repeated now)
+    //to copy this invocation many times (and to comment/uncomment inappropriate functions) to see the difference
+    foo(foo(a, foo(a, foo(a, a.testVal))), a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/specialConstructions/constantsInIf.fir.kt b/compiler/testData/diagnostics/tests/resolve/specialConstructions/constantsInIf.fir.kt
new file mode 100644
index 00000000000..052ad1c675f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/specialConstructions/constantsInIf.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -USELESS_ELVIS
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(if (true) {
+        1
+    } else {
+        2
+    })
+
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(1 ?: 2)
+}
+
+fun bar(s: String) = s
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/specialConstructions/elvisAsCall.fir.kt b/compiler/testData/diagnostics/tests/resolve/specialConstructions/elvisAsCall.fir.kt
new file mode 100644
index 00000000000..ed8ac74968a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/specialConstructions/elvisAsCall.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+package a
+
+interface A
+fun doList(l: List<Int>) = l
+fun doInt(i: Int) = i
+fun getList(): List<Int>? = null
+fun <T> strangeList(f: (T) -> Unit): List<T> = throw Exception("$f")
+fun <T: A> emptyListOfA(): List<T> = throw Exception()
+
+//-------------------------------
+
+fun testElvis(a: Int?, b: Int?) {
+    if (a != null) {
+        doInt(b ?: a)
+    }
+    doList(getList() ?: emptyListOfA()) //should be an error
+    doList(getList() ?: strangeList { doInt(it) }) //lambda was not analyzed
+}
+
+
+fun testDataFlowInfo1(a: Int?, b: Int?) {
+    val c: Int = a ?: b!!
+    doInt(c)
+    // b is nullable if a != null
+    b <!INAPPLICABLE_CANDIDATE!>+<!> 1
+}
+
+fun testDataFlowInfo2(a: Int?, b: Int?) {
+    doInt(a ?: b!!)
+    // b is nullable if a != null
+    b <!INAPPLICABLE_CANDIDATE!>+<!> 1
+}
+
+fun testTypeMismatch(a: String?, b: Any) {
+    <!INAPPLICABLE_CANDIDATE!>doInt<!>(a ?: b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/specialConstructions/exclExclAsCall.fir.kt b/compiler/testData/diagnostics/tests/resolve/specialConstructions/exclExclAsCall.fir.kt
new file mode 100644
index 00000000000..b4f44a1b4e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/specialConstructions/exclExclAsCall.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+package a
+
+interface A
+
+fun <T>id(t: T): T = t
+fun doList(l: List<Int>) = l
+fun doInt(i: Int) = i
+
+fun <T> strangeNullableList(f: (T) -> Unit): List<T>? = throw Exception()
+fun <T: A> emptyNullableListOfA(): List<T>? = null
+
+//-------------------------------
+
+fun testExclExcl() {
+    doList(emptyNullableListOfA()!!) //should be an error here
+    val l: List<Int> = id(emptyNullableListOfA()!!)
+
+    doList(strangeNullableList { doInt(it) }!!) //lambda should be analyzed (at completion phase)
+}
+
+fun testDataFlowInfoAfterExclExcl(a: Int?) {
+    doInt(a!!)
+    a + 1
+}
+
+fun testUnnecessaryExclExcl(a: Int) {
+    doInt(a!!) //should be warning
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/specialConstructions/inferenceForElvis.fir.kt b/compiler/testData/diagnostics/tests/resolve/specialConstructions/inferenceForElvis.fir.kt
new file mode 100644
index 00000000000..acf00f5938c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/specialConstructions/inferenceForElvis.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !CHECK_TYPE
+
+fun <T: Any> foo(f: (T) -> Unit): T? = null // T is used only as return type
+fun test() {
+    val x = foo { it checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }} ?: "" // foo() is inferred as foo<String>, which isn't very good
+    val y: Any = foo { it checkType { _<Any>() } } ?: "" // but for now it's fixed by specifying expected type
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/specialConstructions/multipleSuperClasses.fir.kt b/compiler/testData/diagnostics/tests/resolve/specialConstructions/multipleSuperClasses.fir.kt
new file mode 100644
index 00000000000..3df6767a807
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/specialConstructions/multipleSuperClasses.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+interface A
+interface B
+
+interface C: A, B
+interface D: A, B
+interface E: A, B
+
+fun foo(c: C?, d: D?, e: E?) {
+    val test1: A? = c ?: d ?: e
+
+    val test2: B? = if (false) if (true) c else d else e
+
+    val test3: A? = when {
+        true -> c
+        else -> when {
+            true -> d
+            else -> e
+        }
+    }
+
+    val test4: B? = when (1) {
+        1 -> c
+        2 -> d
+        else -> e
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/specialConstructions/reportTypeMismatchDeeplyOnBranches.fir.kt b/compiler/testData/diagnostics/tests/resolve/specialConstructions/reportTypeMismatchDeeplyOnBranches.fir.kt
new file mode 100644
index 00000000000..05be2916b0c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/specialConstructions/reportTypeMismatchDeeplyOnBranches.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+package b
+
+fun bar(i: Int) = i
+
+fun test(a: Int?, b: Int?) {
+    bar(if (a == null) return else b)
+}
+
+fun test(a: Int?, b: Int?, c: Int?) {
+    bar(if (a == null) return else if (b == null) return else c)
+}
+
+fun test(a: Any?, b: Any?, c: Int?) {
+    bar(if (a == null) if (b == null) c else return else return)
+}
+
+fun test(a: Int?, b: Any?, c: Int?) {
+    bar(if (a == null) {
+        return
+    } else {
+        if (b == null) {
+            return
+        } else {
+            c
+        }
+    })
+}
diff --git a/compiler/testData/diagnostics/tests/resolve/typeParameterInDefaultValueInLocalFunction.fir.kt b/compiler/testData/diagnostics/tests/resolve/typeParameterInDefaultValueInLocalFunction.fir.kt
new file mode 100644
index 00000000000..e08e089c0ad
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/typeParameterInDefaultValueInLocalFunction.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo() {
+    fun <T> bar(x: List<T> = listOf<T>()) {}
+}
+
+fun <T> listOf(): List<T> = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/wrongNumberOfTypeArguments.fir.kt b/compiler/testData/diagnostics/tests/resolve/wrongNumberOfTypeArguments.fir.kt
new file mode 100644
index 00000000000..07fc8b72572
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/wrongNumberOfTypeArguments.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <T> foo(t: T) = t
+
+fun test1() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!><Int, String>("")
+}
+
+
+fun <T, R> bar(t: T, r: R) {}
+
+fun test2() {
+    <!INAPPLICABLE_CANDIDATE!>bar<!><Int>("", "")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/resolve/wrongReceiver.fir.kt b/compiler/testData/diagnostics/tests/resolve/wrongReceiver.fir.kt
new file mode 100644
index 00000000000..e160c818aca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/resolve/wrongReceiver.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+package some
+
+class A()
+
+val Int.some: Int get() = 4
+val Int.foo: Int get() = 4
+
+fun Int.extFun() = 4
+
+fun String.test() {
+    some
+    some.A()
+    "".<!INAPPLICABLE_CANDIDATE!>some<!>
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>
+    "".<!INAPPLICABLE_CANDIDATE!>foo<!>
+
+    <!INAPPLICABLE_CANDIDATE!>extFun<!>()
+    "".<!INAPPLICABLE_CANDIDATE!>extFun<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/safeCall.fir.kt b/compiler/testData/diagnostics/tests/safeCall.fir.kt
new file mode 100644
index 00000000000..d613f2e5768
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/safeCall.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+
+fun f(s: String, action: (String.() -> Unit)?) {
+    s.foo().bar().<!UNRESOLVED_REFERENCE!>action<!>()
+}
+
+fun String.foo() = ""
+
+fun String.bar() = ""
+
+// --------------------------------------------------------
+
+val functions: Map<String, () -> Any> = TODO()
+
+fun run(name: String) = <!INAPPLICABLE_CANDIDATE!>functions[name]()<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/DisabledForKTSimple.fir.kt b/compiler/testData/diagnostics/tests/samConversions/DisabledForKTSimple.fir.kt
new file mode 100644
index 00000000000..e02f9d480f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/DisabledForKTSimple.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference
+// FILE: Runnable.java
+public interface Runnable {
+    void run();
+}
+
+// FILE: 1.kt
+interface K {
+    fun foo1(r: Runnable)
+    fun foo2(r1: Runnable, r2: Runnable)
+}
+fun test(k: K, r: Runnable) {
+    k.foo1(r)
+    k.foo1({})
+
+    k.foo2(r, r)
+    k.foo2({}, {})
+    k.foo2(r, {})
+    k.foo2({}, r)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/GenericSubstitution.fir.kt b/compiler/testData/diagnostics/tests/samConversions/GenericSubstitution.fir.kt
new file mode 100644
index 00000000000..85ccf5612eb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/GenericSubstitution.fir.kt
@@ -0,0 +1,29 @@
+// !LANGUAGE: +NewInference +SamConversionPerArgument
+// !CHECK_TYPE
+// FILE: J.java
+public interface J<T> {
+    void f_t(F<T> f1, F<T> f2);
+    <R> void f_r(F<R> f1, F<R> f2);
+    <R> void f_pr(F<PR<T, R>> f1, F<PR<T, R>> f2);
+}
+
+// FILE: F.java
+public interface F<S> {
+    void apply(S s);
+}
+
+// FILE: PR.java
+public interface PR<X, Y> {}
+
+// FILE: 1.kt
+
+fun test(
+    j: J<String>,
+    f_string: F<String>,
+    f_int: F<Int>,
+    f_pr: F<PR<String, Int>>
+) {
+    j.f_t(f_string) { it checkType { _<String>() } }
+    j.f_r(f_int) { it checkType { _<Int>() } }
+    j.f_pr(f_pr) { it checkType { _<PR<String, Int>>() } }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/GenericSubstitutionKT.fir.kt b/compiler/testData/diagnostics/tests/samConversions/GenericSubstitutionKT.fir.kt
new file mode 100644
index 00000000000..0bf63f43541
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/GenericSubstitutionKT.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument
+// !CHECK_TYPE
+// FILE: F.java
+public interface F<S> {
+    void apply(S s);
+}
+
+// FILE: PR.java
+public interface PR<X, Y> {}
+
+// FILE: 1.kt
+interface K<T> {
+    fun f_t(f1: F<T>, f2: F<T>)
+    fun <R> f_r(f1: F<R>, f2: F<R>)
+    fun <R> f_pr(f1: F<PR<T, R>>, f2: F<PR<T, R>>)
+}
+
+fun test(
+    k: K<String>,
+    f_string: F<String>,
+    f_int: F<Int>,
+    f_pr: F<PR<String, Int>>
+) {
+    k.f_t(f_string) { it checkType { _<String>() } }
+    k.f_r(f_int) { it checkType { _<Int>() } }
+    k.f_pr(f_pr) { it checkType { _<PR<String, Int>>() } }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/OverloadPriority.fir.kt b/compiler/testData/diagnostics/tests/samConversions/OverloadPriority.fir.kt
new file mode 100644
index 00000000000..d89c9c184f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/OverloadPriority.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +NewInference
+// !CHECK_TYPE
+// FILE: Fn.java
+public interface Fn<T, R> {
+    R apply(T t);
+}
+
+// FILE: Fn2.java
+public interface Fn2<T, R> extends Fn<T, R> {}
+
+// FILE: J.java
+public interface J {
+    String foo(Fn<String, Object> f, Object o);
+    int foo(Fn<Object, Object> f, String s); // (Any) -> Any <: (String) -> Any <=> String <: Any
+
+    String bas(Fn<Object, Object> f, Object o);
+    int bas(Fn<Object, String> f, String s); // (Any) -> String <: (Any) -> Any <=> String <: Any
+
+    String bar(Fn<String, Object> f);
+    int bar(Fn2<String, Object> f); // Fn2 seems more specific one even function type same
+}
+
+// FILE: 1.kt
+fun test(j: J) {
+    j.<!AMBIGUITY!>foo<!>({ <!UNRESOLVED_REFERENCE!>it<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Any>() }; "" }, "") <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    j.<!AMBIGUITY!>bas<!>({ <!UNRESOLVED_REFERENCE!>it<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Any>() }; "" }, "") <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    // NI: TODO
+    j.bar { it checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Any>() }; "" } checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/OverloadPriorityKT.fir.kt b/compiler/testData/diagnostics/tests/samConversions/OverloadPriorityKT.fir.kt
new file mode 100644
index 00000000000..a7eea3f18fe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/OverloadPriorityKT.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument
+// !CHECK_TYPE
+// FILE: Fn.java
+public interface Fn<T, R> {
+    R apply(T t);
+}
+
+// FILE: Fn2.java
+public interface Fn2<T, R> extends Fn<T, R> {}
+
+// FILE: 1.kt
+interface K {
+    fun foo(f: Fn<String, Any>): String
+    fun foo(f: Fn<Any, Any>): Int
+
+    fun bas(f: Fn<Any, Any>): String
+    fun bas(f: Fn<Any, String>): Int
+
+    fun bar(f: Fn<String, Any>): String
+    fun bar(f: Fn2<String, Any>): Int
+}
+
+fun test(k: K) {
+    k.<!AMBIGUITY!>foo<!> { <!UNRESOLVED_REFERENCE!>it<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Any>() }; "" } <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    k.<!AMBIGUITY!>bas<!> { <!UNRESOLVED_REFERENCE!>it<!> <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }; "" } <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    // NI: TODO
+    k.bar { it checkType { <!INAPPLICABLE_CANDIDATE!>_<!><Any>() }; "" } checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/SAMAfterSubstitution.fir.kt b/compiler/testData/diagnostics/tests/samConversions/SAMAfterSubstitution.fir.kt
new file mode 100644
index 00000000000..9b2b73d56c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/SAMAfterSubstitution.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +NewInference
+// FILE: J.java
+public interface J<T> {
+    public void foo(T r1, T r2);
+}
+
+// FILE: Runnable.java
+public interface Runnable {
+    void run();
+}
+
+// FILE: 1.kt
+fun test(j: J<Runnable>, r: Runnable) {
+    j.foo(r, r)
+    j.foo(r, {})
+    j.foo({}, r)
+    j.foo({}, {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/SAMAfterSubstitutionKT.fir.kt b/compiler/testData/diagnostics/tests/samConversions/SAMAfterSubstitutionKT.fir.kt
new file mode 100644
index 00000000000..b50318d674c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/SAMAfterSubstitutionKT.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions
+// FILE: Runnable.java
+public interface Runnable {
+    void run();
+}
+
+// FILE: 1.kt
+interface K<T> {
+    fun foo(t1: T, t2: T)
+}
+
+fun test(k: K<Runnable>, r: Runnable) {
+    k.foo(r, r)
+    k.foo(r, {})
+    k.foo({}, r)
+    k.foo({}, {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/SimpleCorrect.fir.kt b/compiler/testData/diagnostics/tests/samConversions/SimpleCorrect.fir.kt
new file mode 100644
index 00000000000..977da70c817
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/SimpleCorrect.fir.kt
@@ -0,0 +1,34 @@
+// !LANGUAGE: +NewInference +SamConversionPerArgument
+// FILE: J.java
+public interface J {
+    public void foo1(Runnable r);
+
+    public void foo2(Runnable r1, Runnable r2);
+
+    public void foo3(Runnable r1, Runnable r2, Runnable r3);
+}
+
+// FILE: Runnable.java
+public interface Runnable {
+    void run();
+}
+
+// FILE: 1.kt
+fun test(j: J, r: Runnable) {
+    j.foo1(r)
+    j.foo1({})
+
+    j.foo2(r, r)
+    j.foo2({}, {})
+    j.foo2(r, {})
+    j.foo2({}, r)
+
+    j.foo3(r, r, r)
+    j.foo3(r, r, {})
+    j.foo3(r, {}, r)
+    j.foo3(r, {}, {})
+    j.foo3({}, r, r)
+    j.foo3({}, r, {})
+    j.foo3({}, {}, r)
+    j.foo3({}, {}, {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/SimpleCorrectKT.fir.kt b/compiler/testData/diagnostics/tests/samConversions/SimpleCorrectKT.fir.kt
new file mode 100644
index 00000000000..dfafa0c65a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/SimpleCorrectKT.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument
+// FILE: Runnable.java
+public interface Runnable {
+    void run();
+}
+
+// FILE: 1.kt
+
+interface K {
+    fun foo1(r: Runnable)
+    fun foo2(r1: Runnable, r2: Runnable)
+    fun foo3(r1: Runnable, r2: Runnable, r3: Runnable)
+}
+fun test(k: K, r: Runnable) {
+    k.foo1(r)
+    k.foo1({})
+
+    k.foo2(r, r)
+    k.foo2({}, {})
+    k.foo2(r, {})
+    k.foo2({}, r)
+
+    k.foo3(r, r, r)
+    k.foo3(r, r, {})
+    k.foo3(r, {}, r)
+    k.foo3(r, {}, {})
+    k.foo3({}, r, r)
+    k.foo3({}, r, {})
+    k.foo3({}, {}, r)
+    k.foo3({}, {}, {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/samConversions/checkSamConversionsAreDisabledByDefault.fir.kt b/compiler/testData/diagnostics/tests/samConversions/checkSamConversionsAreDisabledByDefault.fir.kt
new file mode 100644
index 00000000000..65297f5306b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/samConversions/checkSamConversionsAreDisabledByDefault.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +NewInference
+// FILE: Runnable.java
+public interface Runnable {
+    void run();
+}
+
+// FILE: 1.kt
+
+interface K {
+    fun foo1(r: Runnable)
+    fun foo2(r1: Runnable, r2: Runnable)
+    fun foo3(r1: Runnable, r2: Runnable, r3: Runnable)
+}
+fun test(k: K, r: Runnable) {
+    k.foo1(r)
+    k.foo1({})
+
+    k.foo2(r, r)
+    k.foo2({}, {})
+    k.foo2(r, {})
+    k.foo2({}, r)
+
+    k.foo3(r, r, r)
+    k.foo3(r, r, {})
+    k.foo3(r, {}, r)
+    k.foo3(r, {}, {})
+    k.foo3({}, r, r)
+    k.foo3({}, r, {})
+    k.foo3({}, {}, r)
+    k.foo3({}, {}, {})
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/AmbiguityBetweenRootAndPackage.fir.kt b/compiler/testData/diagnostics/tests/scopes/AmbiguityBetweenRootAndPackage.fir.kt
new file mode 100644
index 00000000000..e9597239b3a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/AmbiguityBetweenRootAndPackage.fir.kt
@@ -0,0 +1,12 @@
+// FILE: root.kt
+fun testFun() = "239"
+
+// FILE: otherPackage.kt
+package test
+
+fun testFun() = 12
+
+// FILE: using.kt
+import test.*
+
+val t: String = testFun()
diff --git a/compiler/testData/diagnostics/tests/scopes/AmbiguousNonExtensions.fir.kt b/compiler/testData/diagnostics/tests/scopes/AmbiguousNonExtensions.fir.kt
new file mode 100644
index 00000000000..d1cd4c0f388
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/AmbiguousNonExtensions.fir.kt
@@ -0,0 +1,18 @@
+// FILE: a.kt
+package a
+
+val v = 1
+fun f() = 1
+
+// FILE: b.kt
+package b
+
+val v = 1
+fun f() = 1
+
+// FILE: main.kt
+import a.*
+import b.*
+
+val vv = <!AMBIGUITY!>v<!>
+val ff = <!AMBIGUITY!>f<!>()
diff --git a/compiler/testData/diagnostics/tests/scopes/NoAmbiguityBetweenRootAndPackage.fir.kt b/compiler/testData/diagnostics/tests/scopes/NoAmbiguityBetweenRootAndPackage.fir.kt
new file mode 100644
index 00000000000..da8f87f823a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/NoAmbiguityBetweenRootAndPackage.fir.kt
@@ -0,0 +1,12 @@
+// FILE: root.kt
+fun testFun() = 12
+
+// FILE: otherPackage.kt
+package test
+
+fun testFun() = 12
+
+// FILE: using.kt
+package test
+
+val t = testFun()
diff --git a/compiler/testData/diagnostics/tests/scopes/VisibilityInClassObject.fir.kt b/compiler/testData/diagnostics/tests/scopes/VisibilityInClassObject.fir.kt
new file mode 100644
index 00000000000..24f2f70e685
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/VisibilityInClassObject.fir.kt
@@ -0,0 +1,33 @@
+fun devNull(obj: Any?) {}
+
+open class A {
+    companion object {
+        val internal_val = 1
+        public val public_val: Int = 2
+        private val private_val = 3
+        protected val protected_val: Int = 5
+    }
+
+    fun fromClass() {
+        devNull(internal_val)
+        devNull(public_val)
+        devNull(private_val)
+        devNull(protected_val)
+    }
+}
+
+fun fromOutside() {
+    devNull(A.internal_val)
+    devNull(A.public_val)
+    devNull(A.<!INAPPLICABLE_CANDIDATE!>private_val<!>)
+    devNull(A.<!INAPPLICABLE_CANDIDATE!>protected_val<!>)
+}
+
+class B: A() {
+    fun fromSubclass() {
+        devNull(A.internal_val)
+        devNull(A.public_val)
+        devNull(A.<!INAPPLICABLE_CANDIDATE!>private_val<!>)
+        devNull(A.<!INAPPLICABLE_CANDIDATE!>protected_val<!>)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/VisibilityInheritModifier.fir.kt b/compiler/testData/diagnostics/tests/scopes/VisibilityInheritModifier.fir.kt
new file mode 100644
index 00000000000..ac6bd941f1c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/VisibilityInheritModifier.fir.kt
@@ -0,0 +1,85 @@
+package b
+
+open class A {
+    internal open fun foo() {}
+}
+
+class B : A() {
+    protected override fun foo() {}
+}
+
+class C : A() {
+    internal override fun foo() {}
+}
+
+//------------
+open class D {
+    private open fun self() : D = this
+}
+
+class E : D() {
+    internal override fun self() = this
+
+    fun test() {
+        val s : E = self()
+    }
+}
+
+//------------
+open class F {
+    protected open fun protected_fun() {}
+}
+
+class G : F() {
+    override fun protected_fun() {}
+}
+
+fun test_fun_stays_protected(g: G) {
+    g.protected_fun()
+}
+
+//------------
+open class H {
+    protected open fun pi_fun() {}
+}
+
+class I : H() {
+    protected override fun pi_fun() {}
+}
+
+class J : H() {
+    internal override fun pi_fun() {}
+}
+
+class K : H() {
+    public override fun pi_fun() {}
+}
+
+//-------------
+interface T {
+    public fun foo() {}
+}
+
+open class L : T {
+    override fun foo() {}
+}
+
+class M : L() {
+    internal override fun foo() {}
+}
+//---------------
+interface R {
+    fun foo() {}
+}
+
+interface P : R {
+    override fun foo() {}
+}
+
+interface Q : R {
+    override fun foo() {}
+}
+
+class S : P, Q {
+    internal override fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/annotationOnClass.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/annotationOnClass.fir.kt
new file mode 100644
index 00000000000..68ffc3d5a0a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/annotationOnClass.fir.kt
@@ -0,0 +1,51 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.*
+
+annotation class Ann(
+        val kc1: KClass<*>,
+        val kc2: KClass<*>,
+        val kc3: KClass<*>,
+        val c: Int,
+        val cc: Int,
+        val cn: Int,
+        val ci: Int,
+        val t1: Int,
+        val t2: Int
+)
+
+@Ann(
+        Nested::class,
+        Inner::class,
+        Interface::class,
+        CONST,
+        Companion.CONST,
+        Nested.CONST,
+        Interface.CONST,
+        a,
+        b()
+)
+class A {
+
+    class Nested {
+        companion object {
+            const val CONST = 2
+        }
+    }
+
+    inner class Inner
+
+    interface Interface {
+        companion object {
+            const val CONST = 3
+        }
+    }
+
+    val a = 1
+    fun b() = 2
+
+    companion object {
+        const val CONST = 1
+        fun foo(): Nested = null!!
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/annotationOnConstructors.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/annotationOnConstructors.fir.kt
new file mode 100644
index 00000000000..d26e5b7c9d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/annotationOnConstructors.fir.kt
@@ -0,0 +1,65 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+import kotlin.reflect.*
+
+annotation class Ann(
+        val kc1: KClass<*>,
+        val kc2: KClass<*>,
+        val kc3: KClass<*>,
+        val c: Int,
+        val cc: Int,
+        val cn: Int,
+        val ci: Int,
+        val t1: Int,
+        val t2: Int
+)
+
+class A
+@Ann(
+        Nested::class,
+        Inner::class,
+        Interface::class,
+        CONST,
+        Companion.CONST,
+        Nested.CONST,
+        Interface.CONST,
+        a,
+        b()
+)
+constructor() {
+
+    @Ann(
+            Nested::class,
+            Inner::class,
+            Interface::class,
+            CONST,
+            Companion.CONST,
+            Nested.CONST,
+            Interface.CONST,
+            a,
+            b()
+    )
+    constructor(dummy: Int) : this()
+
+    class Nested {
+        companion object {
+            const val CONST = 2
+        }
+    }
+
+    inner class Inner
+
+    interface Interface {
+        companion object {
+            const val CONST = 3
+        }
+    }
+
+    val a = 1
+    fun b() = 2
+
+    companion object {
+        const val CONST = 1
+        fun foo(): Nested = null!!
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/classGenericParameters.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/classGenericParameters.fir.kt
new file mode 100644
index 00000000000..b2c9645be50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/classGenericParameters.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A<T : Nested, F: Inner, G: Interface> {
+
+    class Nested
+
+    inner class Inner
+
+    interface Interface
+}
+
+class B<T, F, G> where T : Nested, F: Inner, G: Interface {
+
+    class Nested
+
+    inner class Inner
+
+    interface Interface
+}
+
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/classParents.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/classParents.fir.kt
new file mode 100644
index 00000000000..a87ecd7dbde
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/classParents.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface I<F, G, H>
+
+class A(impl: Interface) : Nested(), Interface by impl, Inner, I<Nested, Interface, Inner> {
+
+    class Nested
+
+    inner class Inner
+
+    interface Interface
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/companionObjectParents.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/companionObjectParents.fir.kt
new file mode 100644
index 00000000000..4dd7a073951
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/companionObjectParents.fir.kt
@@ -0,0 +1,25 @@
+interface I<F, G>
+
+val aImpl: A.Companion.Interface
+    get() = null!!
+
+val bImpl: B.Companion.Interface
+    get() = null!!
+
+interface A {
+    companion object : Nested(), Interface by aImpl, I<Nested, Interface> {
+
+        class Nested
+
+        interface Interface
+    }
+}
+
+class B {
+    companion object : Nested(), Interface by aImpl, I<Nested, Interface> {
+
+        class Nested
+
+        interface Interface
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/companionObjectSuperConstructorArguments.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/companionObjectSuperConstructorArguments.fir.kt
new file mode 100644
index 00000000000..6de00281a0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/companionObjectSuperConstructorArguments.fir.kt
@@ -0,0 +1,19 @@
+open class S(val a: Any, val b: Any, val c: Any) {}
+
+interface A {
+    companion object : S(prop1, prop2, func()) {
+        val prop1 = 1
+        val prop2: Int
+            get() = 1
+        fun func() {}
+    }
+}
+
+class B {
+    companion object : S(prop1, prop2, func()) {
+        val prop1 = 1
+        val prop2: Int
+            get() = 1
+        fun func() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/constructors.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/constructors.fir.kt
new file mode 100644
index 00000000000..886c5b062cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/constructors.fir.kt
@@ -0,0 +1,65 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A(
+        n: Nested = foo(),
+        n2: Nested = Nested(),
+        inn: Inner = null!!,
+        inn2: Inner = Inner(),
+        i: Interface = null!!,
+        c: Int = CONST,
+        cc: Int = Companion.CONST,
+        cn: Int = Nested.CONST,
+        ci: Int = Interface.CONST,
+        t1: Int = a,
+        t2: Int = b()
+) {
+
+    constructor(
+            dummy: Int,
+            n: Nested = foo(),
+            n2: Nested = Nested(),
+            inn: Inner = null!!,
+            inn2: Inner = Inner(),
+            i: Interface = null!!,
+            c: Int = CONST,
+            cc: Int = Companion.CONST,
+            cn: Int = Nested.CONST,
+            ci: Int = Interface.CONST,
+            t1: Int = a,
+            t2: Int = b()
+    ) : this(
+        foo(),
+        Nested(),
+        inn,
+        Inner(),
+        i,
+        CONST,
+        Companion.CONST,
+        Nested.CONST,
+        Interface.CONST,
+        a,
+        b()
+    )
+
+    class Nested {
+        companion object {
+            const val CONST = 2
+        }
+    }
+
+    inner class Inner
+
+    interface Interface {
+        companion object {
+            const val CONST = 3
+        }
+    }
+
+    val a = 1
+    fun b() = 2
+
+    companion object {
+        const val CONST = 1
+        fun foo(): Nested = null!!
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/delegation.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/delegation.fir.kt
new file mode 100644
index 00000000000..b53bcf83750
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/delegation.fir.kt
@@ -0,0 +1,50 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface I
+
+open class S(
+        n: A.Nested,
+        n2: A.Nested,
+        inn: A.Inner,
+        c: Int,
+        cc: Int,
+        cn: Int,
+        ci: Int,
+        t1: Int,
+        t2: Int
+) : I
+
+class A : I by S(
+        foo(),
+        Nested(),
+        Inner(),
+        CONST,
+        Companion.CONST,
+        Nested.CONST,
+        Interface.CONST,
+        a,
+        b()
+) {
+
+    class Nested {
+        companion object {
+            const val CONST = 2
+        }
+    }
+
+    inner class Inner
+
+    interface Interface {
+        companion object {
+            const val CONST = 3
+        }
+    }
+
+    val a = 1
+    fun b() = 2
+
+    companion object {
+        const val CONST = 1
+        fun foo(): Nested = null!!
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/objectParents.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/objectParents.fir.kt
new file mode 100644
index 00000000000..006964e0753
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/objectParents.fir.kt
@@ -0,0 +1,11 @@
+interface I<F, G>
+
+val aImpl: A.Interface
+    get() = null!!
+
+object A : Nested(), Interface by aImpl, I<Nested, Interface> {
+
+    class Nested
+
+    interface Interface
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/objectSuperConstructorArguments.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/objectSuperConstructorArguments.fir.kt
new file mode 100644
index 00000000000..f08b997802d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/objectSuperConstructorArguments.fir.kt
@@ -0,0 +1,8 @@
+open class S(val a: Any, val b: Any, val c: Any) {}
+
+object A : S(prop1, prop2, func()) {
+    val prop1 = 1
+    val prop2: Int
+        get() = 1
+    fun func() {}
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/simpleDelegation.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/simpleDelegation.fir.kt
new file mode 100644
index 00000000000..255ac8e7eb9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/simpleDelegation.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+interface I
+
+class A : I by impl {
+
+    companion object {
+        val impl = object : I {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/superConstructorArguments.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/superConstructorArguments.fir.kt
new file mode 100644
index 00000000000..4a54b354afe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/superConstructorArguments.fir.kt
@@ -0,0 +1,48 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class S(
+        n: A.Nested,
+        n2: A.Nested,
+        inn: A.Inner,
+        c: Int,
+        cc: Int,
+        cn: Int,
+        ci: Int,
+        t1: Int,
+        t2: Int
+)
+
+class A : S (
+    foo(),
+    Nested(),
+    Inner(),
+    CONST,
+    Companion.CONST,
+    Nested.CONST,
+    Interface.CONST,
+    a,
+    b()
+) {
+
+    class Nested {
+        companion object {
+            const val CONST = 2
+        }
+    }
+
+    inner class Inner
+
+    interface Interface {
+        companion object {
+            const val CONST = 3
+        }
+    }
+
+    val a = 1
+    fun b() = 2
+
+    companion object {
+        const val CONST = 1
+        fun foo(): Nested = null!!
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/classHeader/superConstructorArgumentsInSecondaryConstructor.fir.kt b/compiler/testData/diagnostics/tests/scopes/classHeader/superConstructorArgumentsInSecondaryConstructor.fir.kt
new file mode 100644
index 00000000000..c20c5465d08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/classHeader/superConstructorArgumentsInSecondaryConstructor.fir.kt
@@ -0,0 +1,50 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class S(
+        n: A.Nested,
+        n2: A.Nested,
+        inn: A.Inner,
+        c: Int,
+        cc: Int,
+        cn: Int,
+        ci: Int,
+        t1: Int,
+        t2: Int
+)
+
+class A : S {
+
+    constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(
+            foo(),
+            Nested(),
+            Inner(),
+            CONST,
+            Companion.CONST,
+            Nested.CONST,
+            Interface.CONST,
+            a,
+            b()
+    )
+
+    class Nested {
+        companion object {
+            const val CONST = 2
+        }
+    }
+
+    inner class Inner
+
+    interface Interface {
+        companion object {
+            const val CONST = 3
+        }
+    }
+
+    val a = 1
+    fun b() = 2
+
+    companion object {
+        const val CONST = 1
+        fun foo(): Nested = null!!
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/genericVsNested.fir.kt b/compiler/testData/diagnostics/tests/scopes/genericVsNested.fir.kt
new file mode 100644
index 00000000000..afa0b31cac4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/genericVsNested.fir.kt
@@ -0,0 +1,57 @@
+class A<T> {
+    class T
+
+    object E {
+        init {
+            T()
+        }
+    }
+
+    class F {
+        init {
+            T()
+        }
+    }
+
+    inner class I {
+        init {
+            T() // todo: https://jetbrains.quip.com/hPM5AJcc1nca
+        }
+    }
+
+    init {
+        T()
+    }
+}
+
+class B<T> {
+    companion object {
+        class T;
+
+        init {
+            T()
+        }
+    }
+
+    object E {
+        init {
+            T()
+        }
+    }
+
+    class F {
+        init {
+            T()
+        }
+    }
+
+    inner class I {
+        init {
+            T()
+        }
+    }
+
+    init {
+        T()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/implicitReceiverMemberVsParameter.fir.kt b/compiler/testData/diagnostics/tests/scopes/implicitReceiverMemberVsParameter.fir.kt
new file mode 100644
index 00000000000..b798c1f212e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/implicitReceiverMemberVsParameter.fir.kt
@@ -0,0 +1,5 @@
+class A(val foo: Int)
+
+fun A.test(foo: String) {
+    val a: String = foo
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/companionObject.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/companionObject.fir.kt
new file mode 100644
index 00000000000..f34525428d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/companionObject.fir.kt
@@ -0,0 +1,41 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+interface A {
+    companion object {
+        fun foo() {}
+
+        class A_
+    }
+}
+
+open class B {
+    companion object {
+        fun bar() {}
+
+        class B_
+    }
+}
+
+class C: B(), A {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        A.foo()
+        A.Companion.foo()
+        C.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+        <!UNRESOLVED_REFERENCE!>A_<!>()
+        A.A_()
+        A.Companion.A_()
+        C.<!UNRESOLVED_REFERENCE!>A_<!>()
+
+        bar()
+        B.bar()
+        B.Companion.bar()
+        C.<!UNRESOLVED_REFERENCE!>bar<!>()
+
+        B_()
+        B.B_()
+        B.Companion.B_()
+        C.<!UNRESOLVED_REFERENCE!>B_<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/companionObjectAfterJava.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/companionObjectAfterJava.fir.kt
new file mode 100644
index 00000000000..d2a44995123
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/companionObjectAfterJava.fir.kt
@@ -0,0 +1,52 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+// FILE: 1.kt
+interface A {
+    companion object {
+        fun foo() {}
+
+        class A_
+    }
+}
+
+open class B {
+    companion object {
+        fun bar() {}
+
+        class B_
+    }
+}
+
+// FILE: C.java
+public class C extends B implements A {
+
+}
+
+// FILE: 2.kt
+class D: C() {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        A.foo()
+        A.Companion.foo()
+        C.<!UNRESOLVED_REFERENCE!>foo<!>()
+        D.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+        <!UNRESOLVED_REFERENCE!>A_<!>()
+        A.A_()
+        A.Companion.A_()
+        C.<!UNRESOLVED_REFERENCE!>A_<!>()
+        D.<!UNRESOLVED_REFERENCE!>A_<!>()
+
+        bar()
+        B.bar()
+        B.Companion.bar()
+        C.<!UNRESOLVED_REFERENCE!>bar<!>()
+        D.<!UNRESOLVED_REFERENCE!>bar<!>()
+
+        B_()
+        B.B_()
+        B.Companion.B_()
+        C.<!UNRESOLVED_REFERENCE!>B_<!>()
+        D.<!UNRESOLVED_REFERENCE!>B_<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/companionObjectsOrder.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/companionObjectsOrder.fir.kt
new file mode 100644
index 00000000000..d3102b829fb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/companionObjectsOrder.fir.kt
@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+open class A {
+    companion object {
+        fun bar() = 1
+    }
+    init {
+        val a: Int = <!INAPPLICABLE_CANDIDATE!>foo<!>()
+        val b: Int = bar()
+    }
+}
+
+open class B: A() {
+    companion object {
+        fun bar() = ""
+    }
+    init {
+        val a: String = <!INAPPLICABLE_CANDIDATE!>foo<!>()
+        val b: String = bar()
+    }
+}
+
+fun A.Companion.foo() = 1
+fun B.Companion.foo() = ""
+
+class C: A() {
+    init {
+        val a: Int = <!INAPPLICABLE_CANDIDATE!>foo<!>()
+        val b: Int = bar()
+    }
+}
+
+class D: B() {
+    init {
+        val a: String = <!INAPPLICABLE_CANDIDATE!>foo<!>()
+        val b: String = bar()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/innerClasses.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/innerClasses.fir.kt
new file mode 100644
index 00000000000..7db34448a12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/innerClasses.fir.kt
@@ -0,0 +1,66 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+open class A {
+    inner class B {
+        fun foo() {}
+    }
+
+    inner class D
+
+    companion object {
+        class B {
+            fun bar() {}
+        }
+
+        class C
+    }
+
+    init {
+        B().foo()
+        B().<!UNRESOLVED_REFERENCE!>bar<!>()
+
+        D()
+        C()
+    }
+}
+
+class E: A() {
+    init {
+        B().foo()
+        B().<!UNRESOLVED_REFERENCE!>bar<!>()
+
+        D()
+        C()
+    }
+
+    object Z {
+        init {
+            B().foo()
+            B().<!UNRESOLVED_REFERENCE!>bar<!>()
+
+            D()
+            C()
+        }
+    }
+}
+
+class F: A() {
+    class B {
+        fun fas() {}
+    }
+    inner class D {
+        fun f() {}
+    }
+
+    init {
+        B().fas()
+        D().f()
+    }
+
+    companion object {
+        init {
+            B().fas()
+            D().f()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/kt3856.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/kt3856.fir.kt
new file mode 100644
index 00000000000..90c26194add
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/kt3856.fir.kt
@@ -0,0 +1,33 @@
+fun foo(init: A.() -> Unit) { }
+
+class A {
+    var x: Int = 0
+    companion object {
+        val f = foo() {
+            x = 1
+        }
+    }
+}
+
+class B(val a: String) {
+    fun f() = 0
+    companion object   {
+        fun B.bar() = a + f()
+    }
+}
+
+open class C {
+    fun bar() {}
+}
+
+class E: C() {
+
+    class D {
+        init {
+            with(C()) {
+                bar()
+                this.bar()
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/methodsPriority.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/methodsPriority.fir.kt
new file mode 100644
index 00000000000..6cb02f88f68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/methodsPriority.fir.kt
@@ -0,0 +1,34 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    int foo() {return 1;}
+}
+
+// FILE: 1.kt
+
+fun foo() = ""
+
+open class B: A() {
+    init {
+        val a: Int = foo()
+    }
+}
+
+fun test() {
+    fun foo() = ""
+
+    class B: A() {
+        init {
+            val a: Int = foo() // todo
+        }
+    }
+}
+
+class E: A() {
+    fun foo() = A()
+
+    init {
+        val a: A = foo() // todo: discuss
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/nestedClassesFromInterface.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedClassesFromInterface.fir.kt
new file mode 100644
index 00000000000..04981874b40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedClassesFromInterface.fir.kt
@@ -0,0 +1,27 @@
+// FILE: A.java
+public interface A {
+    public class A_ {}
+}
+
+// FILE: 1.kt
+interface B {
+    class B_
+}
+
+class X: A {
+    val a: A_ = A_()
+    val b: A.A_ = A.A_()
+
+    companion object {
+        val a: A_ = A_()
+    }
+}
+
+class Y: B {
+    val a: B_ = B_()
+    val b: B.B_ = B.B_()
+
+    companion object {
+        val b: B_ = B_()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClass.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClass.fir.kt
new file mode 100644
index 00000000000..6e079eb502a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClass.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+open class A {
+    companion object {
+        class B
+    }
+}
+
+class C: A() {
+    val b: B = null!!
+
+    init {
+        B()
+    }
+
+    object O {
+        val b: B = null!!
+
+        init {
+            B()
+        }
+    }
+
+    class K {
+        val b: B = null!!
+
+        init {
+            B()
+        }
+    }
+
+    inner class I {
+        val b: B = null!!
+
+        init {
+            B()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClassVsNested.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClassVsNested.fir.kt
new file mode 100644
index 00000000000..7c2ade5d1f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClassVsNested.fir.kt
@@ -0,0 +1,95 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+open class A {
+    class X {
+        fun A_X() {}
+    }
+
+    class Y {
+        fun A_Y() {}
+    }
+
+    companion object {
+        class X {
+            fun A_C_X() {}
+        }
+
+        class Z {
+            fun A_C_Z() {}
+        }
+    }
+
+    init {
+        X().A_X()
+        X().<!UNRESOLVED_REFERENCE!>A_C_X<!>()
+    }
+}
+
+class Simple: A() {
+    init {
+        Y().A_Y()
+        Z().A_C_Z()
+    }
+}
+
+class B: A() {
+    class Y {
+        fun B_Y() {}
+    }
+
+    class Z {
+        fun B_Z() {}
+    }
+
+    init {
+        X().A_X()
+        X().<!UNRESOLVED_REFERENCE!>A_C_X<!>()
+
+        Y().B_Y()
+        Y().<!UNRESOLVED_REFERENCE!>A_Y<!>()
+
+        Z().B_Z()
+        Z().<!UNRESOLVED_REFERENCE!>A_C_Z<!>()
+    }
+
+    companion object {
+        init {
+            X().A_X()
+            X().<!UNRESOLVED_REFERENCE!>A_C_X<!>()
+
+            Y().B_Y()
+            Y().<!UNRESOLVED_REFERENCE!>A_Y<!>()
+
+            Z().B_Z()
+            Z().<!UNRESOLVED_REFERENCE!>A_C_Z<!>()
+        }
+    }
+}
+
+class C: A() {
+    companion object {
+        class Y {
+            fun C_C_Y() {}
+        }
+
+        class Z {
+            fun C_C_Z() {}
+        }
+
+        init {
+            Y().C_C_Y()
+            Y().<!UNRESOLVED_REFERENCE!>A_Y<!>()
+
+            Z().C_C_Z()
+            Z().<!UNRESOLVED_REFERENCE!>A_C_Z<!>()
+        }
+    }
+
+    init {
+        Y().<!UNRESOLVED_REFERENCE!>C_C_Y<!>()
+        Y().A_Y()
+
+        Z().C_C_Z()
+        Z().<!UNRESOLVED_REFERENCE!>A_C_Z<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClassVsNestedJava.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClassVsNestedJava.fir.kt
new file mode 100644
index 00000000000..d38e63e9ccb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedCompanionClassVsNestedJava.fir.kt
@@ -0,0 +1,47 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+// FILE: 1.kt
+open class A {
+    class Y {
+        fun A_Y() {}
+    }
+
+    companion object {
+        class Z {
+            fun A_C_Z() {}
+        }
+    }
+}
+
+// FILE: B.java
+public class B extends A {
+    class Y {
+        void B_Y() {}
+    }
+
+    class Z {
+        void B_Z() {}
+    }
+}
+
+// FILE: C.java
+public class C extends A {}
+
+// FILE: 2.kt
+class E: B() {
+    init {
+        Y().B_Y()
+        Y().<!UNRESOLVED_REFERENCE!>A_Y<!>()
+
+        Z().B_Z()
+        Z().<!UNRESOLVED_REFERENCE!>A_C_Z<!>()
+    }
+}
+
+class Y: C() {
+    init {
+        Y().A_Y()
+
+        Z().A_C_Z()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/nestedFromJava.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedFromJava.fir.kt
new file mode 100644
index 00000000000..88266ce26d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedFromJava.fir.kt
@@ -0,0 +1,90 @@
+// FILE: A.java
+public interface A {
+    public class A_S { // static
+
+    }
+}
+
+// FILE: B.java
+public class B {
+    public static class B_S {
+
+    }
+    public class B_ {
+
+    }
+}
+
+// FILE: C.java
+public class C extends B implements A {
+
+}
+
+// FILE: 1.kt
+
+class X: A {
+    val a_s: A_S = null!!
+
+    init {
+        A_S()
+        A.A_S()
+        X.A_S()
+    }
+
+    object xD {
+        val a_: A_S = null!!
+
+        init {
+            A_S()
+        }
+    }
+}
+
+class Y: B() {
+    val b_: B_ = null!!
+    val b_s: B_S = null!!
+
+    init {
+        B_()
+        B.<!UNRESOLVED_REFERENCE!>B_<!>()
+        Y.<!UNRESOLVED_REFERENCE!>B_<!>()
+
+        B_S()
+        B.B_S()
+        Y.B_S()
+    }
+
+    object X {
+        val b_: B_ = null!!
+        val b_s: B_S = null!!
+
+        init {
+            B_()
+            B_S()
+        }
+    }
+}
+
+class Z: C() {
+    val a_s: A_S = null!!
+    val b_: B_ = null!!
+    val b_s: B_S = null!!
+
+    init {
+        A_S()
+        B_()
+        B_S()
+    }
+
+    object X {
+        val a_s: A_S = null!!
+        val b_: B_ = null!!
+        val b_s: B_S = null!!
+
+        init {
+            A_S()
+            B_()
+            B_S()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/nestedFromJavaAfterKotlin.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedFromJavaAfterKotlin.fir.kt
new file mode 100644
index 00000000000..17c7d51f07b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedFromJavaAfterKotlin.fir.kt
@@ -0,0 +1,82 @@
+// FILE: A.java
+public interface A {
+    class A_S {
+
+    }
+}
+
+// FILE: B.java
+public class B {
+    static class B_S {
+
+    }
+    class B_ {
+
+    }
+}
+
+// FILE: C.java
+public class C extends B implements A {
+
+}
+
+// FILE: 1.kt
+interface E {
+    class E_S
+}
+
+open class D: C(), E
+
+// FILE: F.java
+public class F extends D {
+
+}
+
+// FILE: 2.kt
+class X: D() {
+    init {
+        B_()
+        B.<!UNRESOLVED_REFERENCE!>B_<!>()
+        C.<!UNRESOLVED_REFERENCE!>B_<!>()
+        D.<!UNRESOLVED_REFERENCE!>B_<!>()
+        X.<!UNRESOLVED_REFERENCE!>B_<!>()
+
+        A_S()
+        A.A_S()
+        C.A_S()
+        D.A_S()
+        X.A_S()
+
+        B_S()
+        B.B_S()
+        C.B_S()
+        D.B_S()
+        X.B_S()
+
+        E_S()
+        E.E_S()
+        D.E_S()
+        X.E_S()
+    }
+}
+
+class Y: F() {
+    init {
+
+        B_()
+        F.<!UNRESOLVED_REFERENCE!>B_<!>()
+        Y.<!UNRESOLVED_REFERENCE!>B_<!>()
+
+        A_S()
+        F.A_S()
+        Y.A_S()
+
+        B_S()
+        F.B_S()
+        Y.B_S()
+
+        E_S()
+        F.E_S()
+        Y.E_S()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/nestedVsToplevelClass.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedVsToplevelClass.fir.kt
new file mode 100644
index 00000000000..6da4e2102e3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/nestedVsToplevelClass.fir.kt
@@ -0,0 +1,38 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+class X {
+    fun T_X() {}
+}
+
+class Y {
+    fun T_Y() {}
+}
+
+open class A {
+    class X {
+        fun A_X() {}
+    }
+    companion object {
+        class Y {
+            fun A_C_Y() {}
+        }
+    }
+
+    init {
+        X().A_X()
+        X().<!UNRESOLVED_REFERENCE!>T_X<!>()
+
+        Y().A_C_Y()
+        Y().<!UNRESOLVED_REFERENCE!>T_Y<!>()
+    }
+}
+
+class B: A() {
+    init {
+        X().A_X()
+        X().<!UNRESOLVED_REFERENCE!>T_X<!>()
+
+        Y().A_C_Y()
+        Y().<!UNRESOLVED_REFERENCE!>T_Y<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/severalCompanions.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/severalCompanions.fir.kt
new file mode 100644
index 00000000000..875eb4cfbf8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/severalCompanions.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+open class A {
+    companion object {
+        fun foo() = 1
+        fun bar(a: String) = a
+    }
+}
+
+open class B: A() {
+    companion object {
+        fun foo() = ""
+        fun bar(a: Int) = a
+    }
+}
+
+class C: B() {
+    init {
+        val a: String = foo()
+        val b: Int = bar(1)
+        val c: String = bar("")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClassJKJ_after.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClassJKJ_after.fir.kt
new file mode 100644
index 00000000000..4e52edab6a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClassJKJ_after.fir.kt
@@ -0,0 +1,55 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: J2.java
+public class J2 extends A {
+    public static void boo() {}
+}
+
+// FILE: test.kt
+open class A {
+    companion object : J() {
+        fun bar() {}
+    }
+}
+
+class B : J2() {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        boo()
+    }
+
+    fun test2() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        boo()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>boo<!>()
+        }
+    }
+
+    companion object {
+        init {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>boo<!>()
+        }
+
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>boo<!>()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClassJKJ_before.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClassJKJ_before.fir.kt
new file mode 100644
index 00000000000..ebf633574e0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClassJKJ_before.fir.kt
@@ -0,0 +1,55 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: J2.java
+public class J2 extends A {
+    public static void boo() {}
+}
+
+// FILE: test.kt
+open class A {
+    companion object : J() {
+        fun bar() {}
+    }
+}
+
+class B : J2() {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        boo()
+    }
+
+    fun test2() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        boo()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>boo<!>()
+        }
+    }
+
+    companion object {
+        init {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>boo<!>()
+        }
+
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>boo<!>()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClass_after.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClass_after.fir.kt
new file mode 100644
index 00000000000..aa556c2c09a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClass_after.fir.kt
@@ -0,0 +1,46 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+open class A {
+    companion object : J() {
+        fun bar() {}
+    }
+}
+
+class B : A() {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    fun test2() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+    }
+
+    companion object {
+        init {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+
+        fun bar() {}
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClass_before.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClass_before.fir.kt
new file mode 100644
index 00000000000..28daf2d8470
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/accessToStaticMembersOfParentClass_before.fir.kt
@@ -0,0 +1,46 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+open class A {
+    companion object : J() {
+        fun bar() {}
+    }
+}
+
+class B : A() {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    fun test2() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+    }
+
+    companion object {
+        init {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+
+        fun bar() {}
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromContainingClass_after.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromContainingClass_after.fir.kt
new file mode 100644
index 00000000000..0df97ac7ee2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromContainingClass_after.fir.kt
@@ -0,0 +1,54 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+open class A<T> : J() {
+    init {
+        foo()
+        bar()
+        val a: Int = baz()
+        val b: T = baz()
+    }
+
+    fun test1() {
+        foo()
+        bar()
+        val a: Int = baz()
+        val b: T = baz()
+    }
+
+    fun baz(): T = null!!
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            val a: Int = <!UNRESOLVED_REFERENCE!>baz<!>()
+            val b: T = <!UNRESOLVED_REFERENCE!>baz<!>()
+        }
+    }
+
+    companion object : A<Int>() {
+        init {
+            foo()
+            bar()
+            val a: Int = baz()
+            val b: T = baz()
+        }
+
+        fun test() {
+            foo()
+            bar()
+            val a: Int = baz()
+            val b: T = baz()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromContainingClass_before.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromContainingClass_before.fir.kt
new file mode 100644
index 00000000000..1f60f0f8568
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromContainingClass_before.fir.kt
@@ -0,0 +1,54 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+open class A<T> : J() {
+    init {
+        foo()
+        bar()
+        val a: Int = baz()
+        val b: T = baz()
+    }
+
+    fun test1() {
+        foo()
+        bar()
+        val a: Int = baz()
+        val b: T = baz()
+    }
+
+    fun baz(): T = null!!
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            val a: Int = <!UNRESOLVED_REFERENCE!>baz<!>()
+            val b: T = <!UNRESOLVED_REFERENCE!>baz<!>()
+        }
+    }
+
+    companion object : A<Int>() {
+        init {
+            foo()
+            bar()
+            val a: Int = baz()
+            val b: T = baz()
+        }
+
+        fun test() {
+            foo()
+            bar()
+            val a: Int = baz()
+            val b: T = baz()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJavaAfterKotlin_after.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJavaAfterKotlin_after.fir.kt
new file mode 100644
index 00000000000..d7a1bdd320f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJavaAfterKotlin_after.fir.kt
@@ -0,0 +1,50 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+
+open class B : J() {
+    fun baz() {}
+}
+
+class A {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        <!UNRESOLVED_REFERENCE!>baz<!>()
+    }
+
+    fun test1() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        <!UNRESOLVED_REFERENCE!>baz<!>()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>baz<!>()
+        }
+    }
+
+
+    companion object : B() {
+        init {
+            foo()
+            bar()
+            baz()
+        }
+
+        fun test() {
+            foo()
+            bar()
+            baz()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJavaAfterKotlin_before.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJavaAfterKotlin_before.fir.kt
new file mode 100644
index 00000000000..79bd44e5627
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJavaAfterKotlin_before.fir.kt
@@ -0,0 +1,50 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+
+open class B : J() {
+    fun baz() {}
+}
+
+class A {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        <!UNRESOLVED_REFERENCE!>baz<!>()
+    }
+
+    fun test1() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+        <!UNRESOLVED_REFERENCE!>baz<!>()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+            <!UNRESOLVED_REFERENCE!>baz<!>()
+        }
+    }
+
+
+    companion object : B() {
+        init {
+            foo()
+            bar()
+            baz()
+        }
+
+        fun test() {
+            foo()
+            bar()
+            baz()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJava_after.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJava_after.fir.kt
new file mode 100644
index 00000000000..2abf7f10610
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJava_after.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: +ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+class A {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    fun test1() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+    }
+
+    companion object : J() {
+        init {
+            foo()
+            bar()
+        }
+
+        fun test() {
+            foo()
+            bar()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJava_before.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJava_before.fir.kt
new file mode 100644
index 00000000000..2e585f6aa21
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/companionObject/inheritFromJava_before.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+// FILE: J.java
+public class J {
+    public static void foo() {}
+}
+
+// FILE: test.kt
+class A {
+    init {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    fun test1() {
+        <!UNRESOLVED_REFERENCE!>foo<!>()
+        bar()
+    }
+
+    object O {
+        fun test() {
+            <!UNRESOLVED_REFERENCE!>foo<!>()
+            bar()
+        }
+    }
+
+    companion object : J() {
+        init {
+            foo()
+            bar()
+        }
+
+        fun test() {
+            foo()
+            bar()
+        }
+
+        fun bar() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/hidePrivateByPublic.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/hidePrivateByPublic.fir.kt
new file mode 100644
index 00000000000..1c704061339
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/hidePrivateByPublic.fir.kt
@@ -0,0 +1,36 @@
+// FILE: A.java
+
+class A {
+    private static int a = 1;
+    private static void foo() {}
+
+    protected static int b = 1;
+    protected static void bar() {}
+}
+
+// FILE: B.java
+
+class B extends A {
+    public static int a = 1;
+    public static void foo() {}
+    public static void foo(int i) {}
+
+    public static int b = 1;
+    public static void bar() {}
+    public static void bar(int i) {}
+}
+
+// FILE: test.kt
+
+fun test() {
+    A.<!INAPPLICABLE_CANDIDATE!>a<!>
+    A.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    A.b
+    A.bar()
+    B.a
+    B.foo()
+    B.foo(1)
+    B.<!AMBIGUITY!>b<!>
+    B.bar()
+    B.bar(1)
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/jjkj.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/jjkj.fir.kt
new file mode 100644
index 00000000000..eacac7619af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/jjkj.fir.kt
@@ -0,0 +1,43 @@
+// FILE: I.java
+
+public interface I {
+    int a = 1;
+}
+
+// FILE: C.java
+
+public class C implements I {
+    static int b = 1;
+    static void bar() {}
+}
+
+// FILE: K.kt
+
+open class K : C()
+
+// FILE: D.java
+
+public class D extends K {
+    static int c = 1;
+    static void baz() {}
+}
+
+// FILE: test.kt
+
+fun test() {
+    I.a
+
+    C.a
+    C.b
+    C.bar()
+
+    K.a
+    K.b
+    K.bar()
+
+    D.a
+    D.b
+    D.c
+    D.bar()
+    D.baz()
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/kjk.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/kjk.fir.kt
new file mode 100644
index 00000000000..cfda01f129f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/kjk.fir.kt
@@ -0,0 +1,37 @@
+// FILE: K.kt
+
+open class K {
+    companion object {
+        fun foo() {}
+    }
+}
+
+// FILE: D.java
+
+class D extends K {
+    static int b = 1;
+    static void bar() {}
+}
+
+// FILE: K.kt
+
+class K2 {
+    companion object {
+        fun baz() {}
+    }
+}
+
+// FILE: test.kt
+
+fun test() {
+    K.foo()
+
+    D.b
+    D.bar()
+    D.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+    K2.<!UNRESOLVED_REFERENCE!>b<!>
+    K2.<!UNRESOLVED_REFERENCE!>bar<!>()
+    K2.<!UNRESOLVED_REFERENCE!>foo<!>()
+    K2.baz()
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/localVsStatic.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/localVsStatic.fir.kt
new file mode 100644
index 00000000000..6c66335bc88
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/localVsStatic.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    public static int foo() {return 1;}
+}
+
+// FILE: 1.kt
+
+fun foo() = ""
+
+class B: A() {
+    init {
+        val a: Int = foo()
+    }
+}
+
+// FILE: 2.kt
+fun test() {
+    fun foo() = ""
+
+    class B: A() {
+        init {
+            val a: Int = foo() // todo
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash0.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash0.fir.kt
new file mode 100644
index 00000000000..679562e8170
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash0.fir.kt
@@ -0,0 +1,32 @@
+// FILE: A.java
+
+public interface A {
+    int field = 1;
+}
+
+// FILE: B.java
+
+public interface B {
+    String field = 1;
+}
+
+// FILE: E.java
+
+public class E implements A, B {
+}
+
+// FILE: O.java
+
+public class O implements A, B {
+    public static double field = 1;
+}
+
+// FILE: test.kt
+
+fun test() {
+    A.field
+    B.field
+
+    E.<!AMBIGUITY!>field<!>
+    O.<!AMBIGUITY!>field<!>
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash1.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash1.fir.kt
new file mode 100644
index 00000000000..5738aa2bdd8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash1.fir.kt
@@ -0,0 +1,32 @@
+// FILE: A.java
+
+public interface A {
+    int field = 1;
+}
+
+// FILE: B.java
+
+public interface B extends A {
+    String field = 1;
+}
+
+// FILE: E.java
+
+public class E implements A, B {
+}
+
+// FILE: O.java
+
+public class O implements A, B {
+    public static double field = 1;
+}
+
+// FILE: test.kt
+
+fun test() {
+    A.field
+    B.<!AMBIGUITY!>field<!>
+
+    E.<!AMBIGUITY!>field<!>
+    O.<!AMBIGUITY!>field<!>
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash2.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash2.fir.kt
new file mode 100644
index 00000000000..ed9da65f567
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/nameClash2.fir.kt
@@ -0,0 +1,66 @@
+// FILE: A.java
+
+public interface A {
+    int field = 1;
+}
+
+// FILE: B.java
+
+public interface B {
+    String field = 1;
+}
+
+// FILE: C.java
+
+public interface C extends A {
+}
+
+// FILE: D.java
+
+public interface D extends B {
+}
+
+// FILE: E.java
+
+public class E implements C, D {
+}
+
+// FILE: EE.java
+
+public class EE extends E {
+}
+
+// FILE: EO.java
+
+public class EO extends E {
+    public static double field = 1;
+}
+
+// FILE: O.java
+
+public class O implements C, D {
+    public static double field = 1;
+}
+
+// FILE: OO.java
+
+public class OO extends O {
+}
+
+// FILE: test.kt
+
+fun test() {
+    A.field
+    B.field
+
+    C.field
+    D.field
+
+    E.<!AMBIGUITY!>field<!>
+    O.<!AMBIGUITY!>field<!>
+
+    EE.<!AMBIGUITY!>field<!>
+    EO.<!AMBIGUITY!>field<!>
+
+    OO.<!AMBIGUITY!>field<!>
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/oneInterfaceManyTimes.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/oneInterfaceManyTimes.fir.kt
new file mode 100644
index 00000000000..5c20a0227ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/oneInterfaceManyTimes.fir.kt
@@ -0,0 +1,55 @@
+// FILE: I.java
+
+public interface I {
+    int a = 1;
+}
+
+// FILE: C.java
+
+public class C implements I {
+    static int b = 1;
+    static void bar() {}
+}
+
+// FILE: K.kt
+
+open class K : C(), I
+
+// FILE: D.java
+
+public class D extends K implements I {
+    static int c = 1;
+    static void baz() {}
+}
+
+// FILE: E.java
+
+public class E extends D implements I {
+    static int a = 1;
+}
+
+// FILE: test.kt
+
+fun test() {
+    I.a
+
+    C.a
+    C.b
+    C.bar()
+
+    K.a
+    K.b
+    K.bar()
+
+    D.a
+    D.b
+    D.c
+    D.bar()
+    D.baz()
+
+    E.<!AMBIGUITY!>a<!>
+    E.b
+    E.c
+    E.bar()
+    E.baz()
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/overloadStatic.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/overloadStatic.fir.kt
new file mode 100644
index 00000000000..a4111820f3f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/overloadStatic.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    static void foo() {}
+    static int bar() { return 1; }
+}
+
+// FILE: B.java
+public class B extends A {
+    static void foo() {}
+    static long bar() { return 1; }
+}
+
+// FILE: 1.kt
+class E: B() {
+    init {
+        foo()
+        val a: Long = bar()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticFunVsImport.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticFunVsImport.fir.kt
new file mode 100644
index 00000000000..39dbe26c492
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticFunVsImport.fir.kt
@@ -0,0 +1,50 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    static void foo() {}
+    static int bar() {return 1;}
+}
+
+// FILE: B.java
+public class B extends A {}
+
+// FILE: C.java
+public class C {
+    static void bar() {}
+}
+
+// FILE: 1.kt
+import A.foo
+import B.bar
+
+class E: A() {
+    init {
+        foo()
+        bar()
+    }
+}
+
+class F: B() {
+    init {
+        foo()
+        bar()
+    }
+}
+
+// FILE: 2.kt
+import C.bar
+
+class Z: A() {
+    init {
+        val a: Int = bar()
+    }
+}
+
+// FILE: 3.kt
+import C.*
+
+class Q: A() {
+    init {
+        val a: Int = bar()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticPropertyVsImport.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticPropertyVsImport.fir.kt
new file mode 100644
index 00000000000..f6e807ba3e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticPropertyVsImport.fir.kt
@@ -0,0 +1,59 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    static byte foo = 1;
+    static int bar = 2;
+}
+
+// FILE: B.java
+public class B extends A {}
+
+// FILE: C.java
+public class C {
+    static long bar = 3;
+}
+
+// FILE: 1.kt
+import A.foo
+import B.bar
+
+class E: A() {
+    init {
+        foo
+        bar
+    }
+}
+
+class F: B() {
+    init {
+        foo
+        bar
+    }
+}
+
+// FILE: 2.kt
+import C.bar
+
+class Z: A() {
+    init {
+        val a: Int = bar
+    }
+}
+
+// FILE: 3.kt
+import C.*
+
+class Q: A() {
+    init {
+        val a: Int = bar
+    }
+}
+
+// FILE: 4.kt
+val bar = ""
+
+class W: A() {
+    init {
+        val a: Int = bar
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsCompanion.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsCompanion.fir.kt
new file mode 100644
index 00000000000..10b07d1924a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsCompanion.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    static void foo() {}
+}
+
+// FILE: 1.kt
+open class B : A() {
+    companion object {
+        fun foo() = 1
+    }
+
+    init {
+        val a: Int = foo()
+    }
+}
+
+class C: B() {
+    init {
+        val a: Int = foo()
+    }
+}
+
+// FILE: X.java
+public class X extends B {
+    static double foo() {
+        return 1.0;
+    }
+}
+
+// FILE: 2.kt
+class Y: X() {
+    init {
+        val a: Double = foo()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsMember.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsMember.fir.kt
new file mode 100644
index 00000000000..bf858b10100
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsMember.fir.kt
@@ -0,0 +1,69 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: A.java
+public class A {
+    public static int foo() { return 1; }
+    public static int bar = 1;
+}
+
+// FILE: 1.kt
+
+class B: A() {
+    companion object {
+        init {
+            val a: Int = <!UNRESOLVED_REFERENCE!>foo<!>()
+            val b: Int = <!UNRESOLVED_REFERENCE!>bar<!>
+        }
+    }
+
+    init {
+        val a: Int = foo()
+        val b: Int = bar
+    }
+}
+
+open class C: A() {
+    val bar = ""
+    fun foo() = ""
+
+    init {
+        val a: String = foo()
+        val b: String = <!AMBIGUITY!>bar<!>
+    }
+}
+
+class E: C() {
+    init {
+        val a: String = foo()
+        val b: String = <!AMBIGUITY!>bar<!>
+    }
+}
+
+open class F: A() {
+    companion object {
+        val bar = ""
+        fun foo() = ""
+
+        init {
+            val a: String = foo()
+            val b: String = bar
+        }
+    }
+    init {
+        val a: String = foo()
+        val b: String = bar
+    }
+}
+
+class G: F() {
+    companion object {
+        init {
+            val a: String = foo()
+            val b: String = bar
+        }
+    }
+
+    init {
+        val a: String = foo()
+        val b: String = bar
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsOuter.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsOuter.fir.kt
new file mode 100644
index 00000000000..b991bb9c2c4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticVsOuter.fir.kt
@@ -0,0 +1,19 @@
+// FILE: A.java
+public class A {
+    public static int foo() {return 1;}
+}
+
+// FILE: B.java
+public class B extends A {
+    public static int foo() {return 1;}
+}
+
+// FILE: 1.kt
+
+fun foo() = ""
+
+class C: B() {
+    init {
+        val a: Int = foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticsFromjava.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticsFromjava.fir.kt
new file mode 100644
index 00000000000..fa3a9af13a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticsFromjava.fir.kt
@@ -0,0 +1,51 @@
+// FILE: A.java
+public class A {
+    public static void foo() {}
+}
+
+// FILE: B.java
+public class B extends A {
+    public static void bar() {}
+}
+
+// FILE: 1.kt
+open class X: A() {
+    init {
+        foo()
+        A.foo()
+    }
+}
+
+open class Y: B() {
+    init {
+        foo()
+        A.foo()
+        B.foo()
+
+        bar()
+        B.bar()
+    }
+}
+
+class XN: X() {
+    init {
+        foo()
+        A.foo()
+        X.foo()
+        XN.foo()
+    }
+}
+
+class YN: Y() {
+    init {
+        foo()
+        A.foo()
+        Y.foo()
+        YN.foo()
+
+        bar()
+        B.bar()
+        Y.bar()
+        YN.bar()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticsFromjavaAfterKotlin.fir.kt b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticsFromjavaAfterKotlin.fir.kt
new file mode 100644
index 00000000000..ebd3679cbb5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/inheritance/statics/staticsFromjavaAfterKotlin.fir.kt
@@ -0,0 +1,27 @@
+// FILE: A.java
+public class A {
+    public static void foo() {}
+}
+
+// FILE: 1.kt
+open class B: A()
+
+// FILE: C.java
+public class C extends B {
+    public static void bar() {}
+}
+
+// FILE: 2.kt
+class D: C() {
+    init {
+        foo()
+        A.foo()
+        B.foo()
+        C.foo()
+        D.foo()
+
+        bar()
+        C.bar()
+        D.bar()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/initializerScopeOfExtensionProperty.fir.kt b/compiler/testData/diagnostics/tests/scopes/initializerScopeOfExtensionProperty.fir.kt
new file mode 100644
index 00000000000..acf064229ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/initializerScopeOfExtensionProperty.fir.kt
@@ -0,0 +1,31 @@
+// NI_EXPECTED_FILE
+
+package i
+
+val <T> List<T>.length = <!UNRESOLVED_REFERENCE!>size<!>
+
+val <T> List<T>.length1 : Int get() = size
+
+val String.bd = this + "!"
+
+val String.bd1 : String get() = this + "!"
+
+
+class A {
+    val ii : Int = 1
+}
+
+val A.foo = <!UNRESOLVED_REFERENCE!>ii<!>
+
+val A.foo1 : Int get() = ii
+
+
+class C {
+    inner class D {}
+}
+
+val C.foo : C.D = <!UNRESOLVED_REFERENCE!>D<!>()
+
+val C.bar : C.D = C().D()
+
+val C.foo1 : C.D get() = D()
diff --git a/compiler/testData/diagnostics/tests/scopes/invisibleSetter.fir.kt b/compiler/testData/diagnostics/tests/scopes/invisibleSetter.fir.kt
new file mode 100644
index 00000000000..d37a025755f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/invisibleSetter.fir.kt
@@ -0,0 +1,9 @@
+class A<T> {
+    public var x: Int = 0
+        private set
+}
+
+fun main() {
+    val a = A<Any>()
+    a.x = 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1078.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1078.fir.kt
new file mode 100644
index 00000000000..aef363bfa9a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1078.fir.kt
@@ -0,0 +1,16 @@
+//KT-1078 Problem with visibility in do-while
+
+package kt1078
+
+fun test() : B {
+    do {
+        val x = foo()
+    } while(x.bar()) // x is not visible here!
+    return B()
+}
+
+class B() {
+    fun bar() = true
+}
+
+fun foo() = B()
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1080.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1080.fir.kt
new file mode 100644
index 00000000000..546784bb76e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1080.fir.kt
@@ -0,0 +1,19 @@
+//FILE:a.kt
+//KT-1080 Don't use previously imported packages while resolving import references
+
+package kt1080
+
+import reflect.Constructor
+
+import b.*
+import d
+import d.Test
+import b.d
+
+class Some: Test()
+
+//FILE:b.kt
+
+package b.d
+
+public open class Test
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1244.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1244.fir.kt
new file mode 100644
index 00000000000..60cec2541c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1244.fir.kt
@@ -0,0 +1,13 @@
+//KT-1244 Frontend allows access to private members of other classes
+
+package kt1244
+
+class A {
+    private var a = ""
+}
+
+class B() {
+    init {
+        A().<!INAPPLICABLE_CANDIDATE!>a<!> = "Hello"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1248.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1248.fir.kt
new file mode 100644
index 00000000000..a083534a2b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1248.fir.kt
@@ -0,0 +1,12 @@
+//KT-1248 Control visibility of overrides needed
+package kt1248
+
+interface ParseResult<out T> {
+    public val success : Boolean
+    public val value : T
+}
+
+class Success<T>(internal override val value : T) : ParseResult<T> {
+    internal override val success : Boolean = true
+}
+
diff --git a/compiler/testData/diagnostics/tests/scopes/kt151.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt151.fir.kt
new file mode 100644
index 00000000000..01a0da63151
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt151.fir.kt
@@ -0,0 +1,40 @@
+//KT-151 Inherit visibility when overriding
+package kt151
+
+open class A {
+    protected open fun x() {}
+}
+
+class B : A() {
+    override fun x() {} // No visibility modifier required
+}
+
+fun test(b: B) {
+    b.x()
+}
+
+
+//more tests
+open class C {
+    internal open fun foo() {}
+}
+
+interface T {
+    fun foo() {}
+}
+
+class D : C(), T {
+    protected override fun foo() {}
+}
+
+class E : C(), T {
+    internal override fun foo() {}
+}
+
+class F : C(), T {
+    private override fun foo() {}
+}
+
+class G : C(), T {
+    public override fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1579.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1579.fir.kt
new file mode 100644
index 00000000000..6c1ef8f6c63
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1579.fir.kt
@@ -0,0 +1,10 @@
+//FILE:a.kt
+//KT-1579 Can't import nested class/interface
+package lib
+interface WithInner {
+    interface Inner {
+    }
+}
+//FILE:b.kt
+package user
+import lib.WithInner.Inner
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1579_map_entry.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1579_map_entry.fir.kt
new file mode 100644
index 00000000000..f9bb0d33c84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1579_map_entry.fir.kt
@@ -0,0 +1,19 @@
+//FILE:a.kt
+//+JDK
+package a
+import kotlin.collections.Map.*
+
+fun foo(b : Entry<String, String>) = b
+
+//FILE:b.kt
+//+JDK
+package b
+
+import kotlin.collections.Map.Entry
+fun bar(b : Entry<String, String>) = b
+
+//FILE:c.kt
+//+JDK
+package c
+
+fun fff(b: Map.Entry<String, String>) = b
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1580.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1580.fir.kt
new file mode 100644
index 00000000000..925f7dab9b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1580.fir.kt
@@ -0,0 +1,15 @@
+//FILE:a.kt
+//KT-1580 Can't access nested class/interface from other package
+package lib
+interface WithInner {
+    interface Inner {
+    }
+}
+
+//FILE:b.kt
+package user
+
+import lib.WithInner
+
+fun main(a : WithInner, b : WithInner.Inner) {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1642.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1642.fir.kt
new file mode 100644
index 00000000000..54819f5e0ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1642.fir.kt
@@ -0,0 +1,9 @@
+//FILE:a.kt
+//KT-1642 kotlin subpackages hide Java's toplevel packages
+package a.java
+
+//FILE:b.kt
+//+JDK
+package a
+
+import java.util.ArrayList
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1738.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1738.fir.kt
new file mode 100644
index 00000000000..1a47ec37bf5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1738.fir.kt
@@ -0,0 +1,11 @@
+//KT-1738 Make it possible to define visibility for constructor parameters which become properties
+
+package kt1738
+
+class A(private var i: Int, var j: Int) {
+}
+
+fun test(a: A) {
+    a.<!INAPPLICABLE_CANDIDATE, INAPPLICABLE_CANDIDATE!>i<!><!UNRESOLVED_REFERENCE!>++<!>
+    a.j++
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1805.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1805.fir.kt
new file mode 100644
index 00000000000..62dd30d6aa1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1805.fir.kt
@@ -0,0 +1,20 @@
+package kt1805
+//KT-1805 Better diagnostic for access to private field of parent class
+
+open class Some {
+    private val privateField = 12
+}
+
+class SomeSubclass : Some() {
+    fun test() {
+        this.<!INAPPLICABLE_CANDIDATE!>privateField<!> // 1. Unresolved reference
+    }
+}
+
+fun test() {
+    val s2 = Some()
+    s2.<!INAPPLICABLE_CANDIDATE!>privateField<!> // 2. Can't access to 'privateField' in Some
+
+    val s1 = SomeSubclass()
+    s1.<!INAPPLICABLE_CANDIDATE!>privateField<!> // 3. Unresolved reference
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1806.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1806.fir.kt
new file mode 100644
index 00000000000..657f069c623
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1806.fir.kt
@@ -0,0 +1,24 @@
+//KT-1806 accessing private member in object class/anonymous object is not highlighted as error
+package kt1806
+
+object MyObject {
+    private var message: String = "'Static'"
+
+}
+
+fun test1() {
+
+    doSmth(MyObject.<!INAPPLICABLE_CANDIDATE!>message<!>)
+}
+
+class Test {
+  private val MyObject1 = object {
+      private var message: String = "'Static'"
+  }
+
+  fun test2() {
+      doSmth(MyObject1.<!INAPPLICABLE_CANDIDATE!>message<!>)
+  }
+}
+
+fun doSmth(s: String) = s
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1822.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1822.fir.kt
new file mode 100644
index 00000000000..ed18d966a00
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1822.fir.kt
@@ -0,0 +1,30 @@
+//KT-1822 Error 'cannot infer visibility' required
+package kt1822
+
+open class C {
+    internal open fun foo() {}
+}
+
+interface T {
+    protected fun foo() {}
+}
+
+class G : C(), T {
+    override fun foo() {} //should be an error "cannot infer visibility"; for now 'public' is inferred in such cases
+}
+
+open class A {
+    internal open fun foo() {}
+}
+
+interface B {
+    protected fun foo() {}
+}
+
+interface D {
+    public fun foo() {}
+}
+
+class E : A(), B, D {
+    override fun foo() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt1942.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt1942.fir.kt
new file mode 100644
index 00000000000..c5bca2a4f52
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt1942.fir.kt
@@ -0,0 +1,19 @@
+//FILE:a/C.java
+//KT-1942 Package local members from Java are visible in subclasses
+package a;
+
+public class C {
+    int myValue;
+}
+
+//FILE:d.kt
+
+package d
+
+import a.C
+
+class A : C() {
+    fun test() {
+        val v = <!INAPPLICABLE_CANDIDATE!>myValue<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/kt2262.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt2262.fir.kt
new file mode 100644
index 00000000000..c78be35d876
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt2262.fir.kt
@@ -0,0 +1,16 @@
+package kt2262
+
+//KT-2262 Cannot access protected member from inner class of subclass
+
+abstract class Foo {
+    protected val color: String = "red"
+}
+
+class Bar : Foo() {
+    protected val i: Int = 1
+
+    inner class Baz {
+        val copy = color // INVISIBLE_MEMBER: Cannot access 'color' in 'Bar'
+        val j = i
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt250.617.10.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt250.617.10.fir.kt
new file mode 100644
index 00000000000..9dc7be2c959
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt250.617.10.fir.kt
@@ -0,0 +1,49 @@
+package kt_250_617_10
+
+import java.util.ArrayList
+import java.util.HashMap
+
+//KT-250 Incorrect variable resolve in constructor arguments of superclass
+open class A(val x: Int)
+class B(y: Int) : A(x)  //x is resolved as a property in a, so no error is generated
+
+//KT-617 Prohibit dollars in call to superclass constructors
+open class M(p: Int)
+class N(val p: Int) : A(<!SYNTAX!><!SYNTAX!><!>$p<!><!SYNTAX!>)<!>
+
+//KT-10 Don't allow to use properties in supertype initializers
+open class Element()
+class TextElement(name: String) : Element()
+
+abstract class Tag(val name : String) {
+  val children = ArrayList<Element>()
+  val attributes = HashMap<String, String>()
+}
+
+abstract class TagWithText(name : String) : Tag(name) {
+  operator fun String.unaryPlus() {
+    children.add(TextElement(this))
+  }
+}
+
+open class BodyTag(name : String) : TagWithText(name) {
+}
+
+class Body() : BodyTag(name) { // Must be an error!
+}
+class Body1() : BodyTag(this.name) { // Must be an error!
+}
+
+//more tests
+
+open class X(p: Int, r: Int) {
+    val s = "s"
+}
+
+class Y(i: Int) : X(i, rrr) {
+    val rrr = 3
+}
+
+class Z(val i: Int) : <!INAPPLICABLE_CANDIDATE!>X<!>(s, x) {
+    val x = 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt323.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt323.fir.kt
new file mode 100644
index 00000000000..e1cf65d75ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt323.fir.kt
@@ -0,0 +1,18 @@
+//KT-323 Handle visibility interactions with overriding
+package kt323
+
+open class A {
+    open var a : Int = 0
+}
+
+class B : A() {
+    override val a = 34
+
+    var b : Int
+        public get() = 23
+        set(i: Int) {}
+
+    protected var c : Int
+        get() = 23
+        private set(i: Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt37.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt37.fir.kt
new file mode 100644
index 00000000000..f97b49359ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt37.fir.kt
@@ -0,0 +1,16 @@
+//KT-37 Typechecker doesn't complain about accessing non-public property
+package kt37
+
+class C() {
+    private var f: Int
+
+    init {
+        f = 610
+    }
+}
+
+fun box(): String {
+    val c = C()
+    if (c.<!INAPPLICABLE_CANDIDATE!>f<!> != 610) return "fail"
+    return "OK"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt587.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt587.fir.kt
new file mode 100644
index 00000000000..9e4b325ea89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt587.fir.kt
@@ -0,0 +1,11 @@
+// KT-587 Unresolved reference
+
+class Main {
+    companion object {
+        class States() {
+            companion object {
+                public val N: States = States() // : States unresolved
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/kt900-1.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt900-1.fir.kt
new file mode 100644
index 00000000000..e6f71feeacb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt900-1.fir.kt
@@ -0,0 +1,24 @@
+// import all members from companion object
+package c
+
+import c.A.Companion.B
+import c.M.*
+
+fun foo() {
+    val b: B = B()
+    var r: R = R()
+}
+
+class A() {
+    companion object {
+        class B() {
+            companion object {
+            }
+        }
+    }
+}
+
+object M {
+    fun foo() {}
+    class R() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt900-2.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt900-2.fir.kt
new file mode 100644
index 00000000000..2decad45f6b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt900-2.fir.kt
@@ -0,0 +1,33 @@
+package d
+
+//import from objects before properties resolve
+
+import d.A.*
+import d.M.R
+import d.M.R.bar
+import d.M.T
+import d.M.Y
+
+var r: T = T()
+val y: T = Y
+
+fun f() {
+    bar()
+    R.bar()
+    B.foo()
+}
+
+object M {
+    object R {
+        fun bar() {}
+    }
+    open class T() {}
+
+    object Y : T() {}
+}
+
+object A {
+    object B {
+        fun foo() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt900.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt900.fir.kt
new file mode 100644
index 00000000000..8aab758b541
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt900.fir.kt
@@ -0,0 +1,69 @@
+//FILE:a.kt
+//KT-900 Inaccessible class should be unresolved
+
+package a
+
+fun foo() {
+    val b : B = <!UNRESOLVED_REFERENCE!>B<!>() //only B() is unresolved, but in ": B" and "B.foo()" B should also be unresolved
+    <!UNRESOLVED_REFERENCE!>B<!>.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+    <!UNRESOLVED_REFERENCE!>P<!>.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+    <!UNRESOLVED_REFERENCE!>M<!>.<!UNRESOLVED_REFERENCE!>bar<!>()
+}
+
+class A() {
+    companion object {
+        class B() {
+            companion object {
+                fun foo() {}
+            }
+        }
+
+        object P {
+            fun foo() {}
+        }
+    }
+}
+
+object N {
+    object M {
+        fun bar() {}
+    }
+}
+
+//FILE:b.kt
+package b
+
+import b.N.M
+import b.A.Companion.P
+import b.A.Companion.B
+
+fun foo() {
+    val b : B = B()
+    B.foo()
+
+    P.foo()
+
+    M.bar()
+}
+
+class A() {
+    companion object {
+        class B() {
+            companion object {
+                fun foo() {}
+            }
+        }
+
+        object P {
+            fun foo() {}
+        }
+    }
+}
+
+object N {
+    object M {
+        fun bar() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/kt939.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt939.fir.kt
new file mode 100644
index 00000000000..6abc2f93dfa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt939.fir.kt
@@ -0,0 +1,18 @@
+package kt939
+
+//KT-939 CommonSupertypes erases scopes associated to types
+
+fun compare(o1 : String?, o2 : String?) : Int {
+    val l1 = o1?.length ?: 0
+    val l2 = o2?.length ?: 0
+    return l1 - l2 // '-' is unresolved, because the type of l1 is Int with an empty member scope
+}
+
+//KT-1117 Unresolved reference to multiply sign
+
+fun test() {
+    (System.getProperty("path.separator")?.length ?: 4) * 55 + 5
+
+    val x = System.getProperty("path.separator")?.length ?: 4
+    x * 55 + 5
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/kt9430.fir.kt b/compiler/testData/diagnostics/tests/scopes/kt9430.fir.kt
new file mode 100644
index 00000000000..6ae08ad0b74
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/kt9430.fir.kt
@@ -0,0 +1,16 @@
+open class A {
+    protected fun foo() {}
+}
+
+class B: A()
+
+class C: A() {
+    fun bar() {
+        A().foo()
+        B().foo()
+    }
+}
+
+class D {
+    fun qux() { B().<!INAPPLICABLE_CANDIDATE!>foo<!>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/complexCompanion.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/complexCompanion.fir.kt
new file mode 100644
index 00000000000..d21b87baa85
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/complexCompanion.fir.kt
@@ -0,0 +1,18 @@
+open class A {
+    protected fun foo() {}
+
+    init {
+        B.foo() // Ok, receiver (B.Companion) is subtype of A
+        (B.Companion).foo()
+    }
+}
+
+class B {
+    companion object : A()
+}
+
+class C: A() {
+    init {
+        B.foo() // Error: receiver is not suitable
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/constructors.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/constructors.fir.kt
new file mode 100644
index 00000000000..bdb52a79479
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/constructors.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class A protected constructor(x: Int) {
+    protected constructor() : this(1)
+    protected constructor(x: String) : this(2)
+    public constructor(x: Double) : this(3)
+}
+
+fun foo() {
+    <!INAPPLICABLE_CANDIDATE!>A<!>()
+    A(1.0)
+}
+
+class B1 : A(1) {}
+class B2 : A() {}
+class B3 : A("") {}
+
+class B4 : A {
+    constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(1)
+    constructor(x: Int) : super()
+    constructor(x: Int, y: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>("")
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/constructorsInner.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/constructorsInner.fir.kt
new file mode 100644
index 00000000000..d2fdff585a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/constructorsInner.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class Outer {
+    inner open class A protected constructor(x: Int) {
+        protected constructor() : this(1)
+
+        protected constructor(x: String) : this(2)
+    }
+
+    inner class B1 : A(1) {}
+    inner class B2 : A() {}
+    inner class B3 : A("") {}
+
+    inner class B4 : A {
+        constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(1)
+        constructor(x: Int) : super()
+        constructor(x: Int, y: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>("")
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/innerClassInJava.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/innerClassInJava.fir.kt
new file mode 100644
index 00000000000..ef6809e9dba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/innerClassInJava.fir.kt
@@ -0,0 +1,24 @@
+// FILE: p1/BaseClass.java
+
+package p1;
+
+public class BaseClass {
+    protected class ProtSubClass {
+        public ProtSubClass() {}
+    }
+}
+
+// FILE: k1/main.kt
+package k1
+
+import p1.BaseClass
+
+class Foo : BaseClass() {
+
+    fun foo() {
+        ProtSubClass()
+        super.ProtSubClass()
+    }
+
+    private val v1: BaseClass.ProtSubClass = ProtSubClass()
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/innerProtectedClass.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/innerProtectedClass.fir.kt
new file mode 100644
index 00000000000..e0e8817a654
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/innerProtectedClass.fir.kt
@@ -0,0 +1,13 @@
+open class BaseClass() {
+    protected class Nested(val x: Int, protected val y: Int)
+
+    protected fun foo() = Nested(1, 2)
+}
+
+class Foo : BaseClass() {
+    fun bar() {
+        val f = foo()
+        f.x
+        f.<!INAPPLICABLE_CANDIDATE!>y<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/javaInheritedInKotlin.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/javaInheritedInKotlin.fir.kt
new file mode 100644
index 00000000000..f1aa94d4fbd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/javaInheritedInKotlin.fir.kt
@@ -0,0 +1,58 @@
+// FILE: bar/JavaClass.java
+
+package bar;
+
+public class JavaClass {
+    protected void foo() {}
+    protected static void bar1() {}
+    protected static void bar2() {}
+
+    protected String field = "";
+    protected static String CONST1 = "";
+    protected static String CONST2 = "";
+
+}
+
+// FILE: foo/JavaClassSamePackage.java
+package foo;
+
+public class JavaClassSamePackage extends bar.JavaClass {
+    protected static void bar2() {}
+    protected static String CONST2 = "";
+}
+
+// FILE: foo/main.kt
+package foo
+
+import bar.JavaClass
+
+class KotlinClass : JavaClass() {
+    fun baz() {
+        foo() // OK
+    }
+}
+
+class KotlinClass2 : JavaClass() {
+    override fun foo() {}
+
+    val field: String = "abc"
+}
+
+fun test(a: KotlinClass, b: KotlinClass2) {
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>() // Error, protected_and_package declared in different package
+    b.foo() // Error, protected visibility in same package (but could be protected_and_package)
+
+    a.<!INAPPLICABLE_CANDIDATE!>field<!>
+
+    JavaClass.<!INAPPLICABLE_CANDIDATE!>bar1<!>()
+    JavaClass.<!INAPPLICABLE_CANDIDATE!>CONST1<!>
+
+    KotlinClass.<!INAPPLICABLE_CANDIDATE!>bar1<!>() // Currently it's unresolved, but it should be prohibited even in case it would be resolved
+    KotlinClass.<!INAPPLICABLE_CANDIDATE!>CONST1<!>
+
+    JavaClassSamePackage.<!INAPPLICABLE_CANDIDATE!>bar1<!>()
+    JavaClassSamePackage.bar2()
+
+    JavaClassSamePackage.<!INAPPLICABLE_CANDIDATE!>CONST1<!>
+    JavaClassSamePackage.CONST2
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/kt7971.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/kt7971.fir.kt
new file mode 100644
index 00000000000..ba80133817d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/kt7971.fir.kt
@@ -0,0 +1,22 @@
+// !CHECK_TYPE
+// FILE: module1/AbstractModule.java
+package module1;
+
+public abstract class AbstractModule<S> {
+    protected <T> S bind(Class<T> clazz) { return null; }
+}
+
+// FILE: module2/main.kt
+package module2
+
+import module1.*
+
+fun <T> javaClass(): Class<T> = null!!
+
+public class AppServiceModule : AbstractModule<String>() {
+    inline fun <reified T> AbstractModule<Int>.bind() {
+        val x = bind(javaClass<T>())
+
+        x checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() } // check that Class receiver is used instead of extension one
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructor.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructor.fir.kt
new file mode 100644
index 00000000000..2ab8196cd5d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructor.fir.kt
@@ -0,0 +1,27 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class A protected constructor(x: Int) {
+    protected constructor() : this(1)
+    public constructor(x: Double) : this(3)
+}
+
+class B4 : A(1) {
+    init {
+        A()
+        A(1)
+        A(5.0)
+    }
+
+    fun foo() {
+        A()
+        A(1)
+        A(5.0)
+
+        object : A() {}
+        object : A(1) {}
+        object : A(5.0) {}
+
+        class Local : A()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructorJavaDifferentPackage.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructorJavaDifferentPackage.fir.kt
new file mode 100644
index 00000000000..679c584e96c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructorJavaDifferentPackage.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: abc/A.java
+package abc;
+public class A {
+    protected A() {}
+    protected A(int x) {}
+    public A(double x) {}
+}
+
+// FILE: main.kt
+import abc.*
+
+class B4 : A(1) {
+    init {
+        A()
+        A(1)
+        A(5.0)
+    }
+
+    fun foo() {
+        A()
+        A(1)
+        A(5.0)
+
+        object : A() {}
+        object : A(1) {}
+        object : A(5.0) {}
+
+        class Local : A()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructorJavaSamePackage.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructorJavaSamePackage.fir.kt
new file mode 100644
index 00000000000..bf4789a773e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/nonSuperCallConstructorJavaSamePackage.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+public class A {
+    protected A() {}
+    protected A(int x) {}
+    public A(double x) {}
+}
+
+// FILE: main.kt
+
+class B4 : A(1) {
+    init {
+        A()
+        A(1)
+        A(5.0)
+    }
+
+    fun foo() {
+        A()
+        A(1)
+        A(5.0)
+
+        object : A() {}
+        object : A(1) {}
+        object : A(5.0) {}
+
+        class Local : A()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/protectedCallOnSubClass.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/protectedCallOnSubClass.fir.kt
new file mode 100644
index 00000000000..2a48ebec1a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/protectedCallOnSubClass.fir.kt
@@ -0,0 +1,15 @@
+open class A {
+    open protected fun foo() { }
+    open protected fun foobaz() { }
+
+    fun bar(x: B) {
+        x.foo() // OK, foo declared in A
+        x.<!INAPPLICABLE_CANDIDATE!>baz<!>() // Declared in B
+        x.foobaz() // Declared in B
+    }
+}
+
+class B : A() {
+    protected fun baz() {}
+    override fun foobaz() {}
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/smartcastOnExtensionReceiver.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/smartcastOnExtensionReceiver.fir.kt
new file mode 100644
index 00000000000..54b92ee84c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/smartcastOnExtensionReceiver.fir.kt
@@ -0,0 +1,9 @@
+abstract class A<T : Any> {
+    abstract protected fun T.foo()
+
+    fun bar(x: T?) {
+        if (x != null) {
+            x.foo()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/syntheticPropertyExtensions.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/syntheticPropertyExtensions.fir.kt
new file mode 100644
index 00000000000..52bdddb16ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/syntheticPropertyExtensions.fir.kt
@@ -0,0 +1,45 @@
+// FILE: abc/A.java
+package abc;
+public class A {
+    public int getAbc() {}
+    protected int getFoo() { return 1; }
+
+    public String getBar() { return ""; }
+    protected void setBar(String x) {  }
+}
+
+// FILE: main.kt
+import abc.A
+
+class Data(var x: A)
+
+class B : A() {
+    fun baz(a: A, b: B, d: Data) {
+        foo
+        bar = bar + ""
+
+        b.foo
+        b.bar = b.bar + ""
+
+        a.foo
+        // TODO: should be INVISIBLE_SETTER
+        a.bar = a.bar + ""
+
+        if (a is B) {
+            a.foo
+            a.bar = a.bar + ""
+        }
+
+        if (d.x is B) {
+            d.x.abc // Ok
+            d.x.foo
+            // TODO: should be INVISIBLE_SETTER
+            d.x.bar = d.x.bar + ""
+        }
+    }
+}
+
+fun baz(a: A) {
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>
+    a.bar = a.bar + ""
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/syntheticSAMExtensions.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/syntheticSAMExtensions.fir.kt
new file mode 100644
index 00000000000..a36bbbcebd6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/syntheticSAMExtensions.fir.kt
@@ -0,0 +1,31 @@
+// !WITH_NEW_INFERENCE
+// FILE: abc/A.java
+package abc;
+public class A {
+    protected void foo(Runnable x) {}
+}
+
+// FILE: main.kt
+import abc.A;
+
+class Data(var x: A)
+
+class B : A() {
+    fun baz(a: A, b: B, d: Data) {
+        a.foo { }
+
+        b.foo { }
+
+        if (a is B) {
+            a.foo {}
+        }
+
+        if (d.x is B) {
+            d.x.foo {}
+        }
+    }
+}
+
+fun baz(a: A) {
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!> { }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/unstableSmartCast.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/unstableSmartCast.fir.kt
new file mode 100644
index 00000000000..afa407fe22f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/unstableSmartCast.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+open class BaseOuter {
+    protected fun foo() = 1
+    protected fun bar() { }
+}
+
+class Foo(var base: BaseOuter)
+
+fun BaseOuter.foo(): String = ""
+
+class Derived : BaseOuter() {
+    fun test(foo: Foo) {
+        if (foo.base is Derived) {
+            foo.base.foo() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() } // Resolved to extension
+            foo.base.bar()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/protectedVisibility/withSmartcast.fir.kt b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/withSmartcast.fir.kt
new file mode 100644
index 00000000000..e6f83a964cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/protectedVisibility/withSmartcast.fir.kt
@@ -0,0 +1,30 @@
+open class Base {
+    open protected fun foo() {}
+    open protected fun bar() {}
+
+    open protected var x: Int = 1
+    open var y: Int = 1
+        protected set
+}
+
+class Derived : Base() {
+    override fun bar() { }
+
+    protected fun baz(x: Base) {
+        x.foo()
+        x.bar()
+
+        x.x = x.x + 1
+        x.y = x.y + 1
+
+        if (x is Derived) {
+            x.foo()
+            x.bar()
+            x.baz(x)
+
+            x.x = x.x + 1
+            // TODO: Should be smart cast
+            x.y = x.y + 1
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/sameClassNameResolve.fir.kt b/compiler/testData/diagnostics/tests/scopes/sameClassNameResolve.fir.kt
new file mode 100644
index 00000000000..79d3a50776a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/sameClassNameResolve.fir.kt
@@ -0,0 +1,10 @@
+// FILE: SameClassNameResolveTest.kt
+package test
+
+open class Base
+class SubBase: Base()
+
+// FILE: SameClassNameResolveRoot.kt
+
+open class Base
+class SubBase: Base()
diff --git a/compiler/testData/diagnostics/tests/scopes/stopResolutionOnAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/scopes/stopResolutionOnAmbiguity.fir.kt
new file mode 100644
index 00000000000..8e128007ae8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/stopResolutionOnAmbiguity.fir.kt
@@ -0,0 +1,20 @@
+package c
+
+interface B {
+    fun bar() {}
+}
+
+class C() {
+    fun bar() {
+    }
+}
+
+fun test(a : Any?) {
+    if (a is B) {
+        if (a is C) {
+            a.<!AMBIGUITY!>bar<!>();
+        }
+    }
+}
+
+fun Any?.bar() {}
diff --git a/compiler/testData/diagnostics/tests/scopes/visibility.fir.kt b/compiler/testData/diagnostics/tests/scopes/visibility.fir.kt
new file mode 100644
index 00000000000..a6c408dbc7f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/visibility.fir.kt
@@ -0,0 +1,95 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+//FILE:a.kt
+package test_visibility
+
+protected class ProtectedClass
+protected interface ProtectedTrait
+
+protected val protected_val : Int = 4
+protected fun protected_fun() {}
+
+private val private_val : Int = 4
+private fun private_fun() {}
+
+val internal_val : Int = 34
+fun internal_fun() {}
+
+fun test1() {
+    private_fun();
+}
+
+class Y {
+    fun test2() {
+        private_fun();
+    }
+}
+
+class A {
+    private val i = 23
+    private val v: B = B()
+    private fun f(i: Int): B = B()
+
+    fun test() {
+        doSmth(i)
+    }
+}
+
+class B {
+    fun bMethod() {}
+}
+
+fun test3(a: A) {
+    a.<!INAPPLICABLE_CANDIDATE!>v<!> //todo .bMethod()
+    a.<!INAPPLICABLE_CANDIDATE!>f<!>(0, 1) //todo .bMethod()
+}
+
+interface T
+
+open class C : T {
+    protected var i : Int = 34
+    fun test5() {
+        doSmth(i)
+    }
+}
+
+fun test4(c: C) {
+    c.<!INAPPLICABLE_CANDIDATE, INAPPLICABLE_CANDIDATE!>i<!><!UNRESOLVED_REFERENCE!>++<!>
+}
+
+class D : C() {
+    val j = i
+    fun test6() {
+        doSmth(i)
+    }
+}
+
+class E : C() {
+    fun test7() {
+        doSmth(i)
+    }
+}
+
+class F : C() {
+    fun test8(c: C) {
+        doSmth(c.i)
+    }
+}
+
+class G : T {
+    fun test8(c: C) {
+        doSmth(c.<!INAPPLICABLE_CANDIDATE!>i<!>)
+    }
+}
+
+fun doSmth(i: Int) = i
+
+//FILE:b.kt
+package test_visibility2
+
+import test_visibility.*
+
+fun test() {
+    internal_fun()
+    <!INAPPLICABLE_CANDIDATE!>private_fun<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/visibility2.fir.kt b/compiler/testData/diagnostics/tests/scopes/visibility2.fir.kt
new file mode 100644
index 00000000000..e17a0496bd2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/visibility2.fir.kt
@@ -0,0 +1,49 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// JAVAC_EXPECTED_FILE
+//FILE:a.kt
+package a
+
+private open class A {
+    fun bar() {}
+}
+
+private fun foo() {}
+
+fun makeA() = A()
+
+private object PO {}
+
+//FILE:b.kt
+//+JDK
+package b
+
+import a.A
+import a.foo
+import a.makeA
+import a.PO
+
+fun test() {
+    val y = makeA()
+    y.bar()
+    <!INAPPLICABLE_CANDIDATE!>foo<!>()
+
+    val u : A = <!INAPPLICABLE_CANDIDATE!>A<!>()
+    val a : java.util.Arrays.ArrayList<Int>;
+
+    val po = <!INAPPLICABLE_CANDIDATE!>PO<!>
+}
+
+class B : <!INAPPLICABLE_CANDIDATE!>A<!>() {}
+
+class Q {
+    class W {
+        fun foo() {
+            val y = makeA() //assure that 'makeA' is visible
+        }
+    }
+}
+
+//check that 'toString' can be invoked without specifying return type
+class NewClass : java.util.ArrayList<Integer>() {
+    public override fun toString() = "a"
+}
diff --git a/compiler/testData/diagnostics/tests/scopes/visibility3.fir.kt b/compiler/testData/diagnostics/tests/scopes/visibility3.fir.kt
new file mode 100644
index 00000000000..cfcf09a19a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/scopes/visibility3.fir.kt
@@ -0,0 +1,47 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+//FILE:file1.kt
+package a
+
+private open class A {
+    fun bar() {}
+}
+
+private var x: Int = 10
+
+private fun foo() {}
+
+private fun bar() {
+    val y = x
+    x = 20
+}
+
+fun makeA() = A()
+
+private object PO {}
+
+//FILE:file2.kt
+package a
+
+fun test() {
+    val y = makeA()
+    y.bar()
+    <!INAPPLICABLE_CANDIDATE!>foo<!>()
+
+    val u : A = <!INAPPLICABLE_CANDIDATE!>A<!>()
+
+    val z = <!INAPPLICABLE_CANDIDATE!>x<!>
+    <!INAPPLICABLE_CANDIDATE!>x<!> = 30
+
+    val po = <!INAPPLICABLE_CANDIDATE!>PO<!>
+}
+
+class B : <!INAPPLICABLE_CANDIDATE!>A<!>() {}
+
+class Q {
+    class W {
+        fun foo() {
+            val y = makeA() //assure that 'makeA' is visible
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/DerivedTopLevel.fir.kt b/compiler/testData/diagnostics/tests/sealed/DerivedTopLevel.fir.kt
new file mode 100644
index 00000000000..f766faf3d9a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/DerivedTopLevel.fir.kt
@@ -0,0 +1,10 @@
+sealed class Base
+
+class Derived: Base() {
+    class Derived2: Base()
+}
+
+fun test() {
+    class Local: Base()
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/DoubleInner.fir.kt b/compiler/testData/diagnostics/tests/sealed/DoubleInner.fir.kt
new file mode 100644
index 00000000000..a4be675f925
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/DoubleInner.fir.kt
@@ -0,0 +1,9 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+        // It's ALLOWED to inherit Sealed also here
+        object Fourth: Sealed(78)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnRoot.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnRoot.fir.kt
new file mode 100644
index 00000000000..afef06f3764
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnRoot.fir.kt
@@ -0,0 +1,23 @@
+sealed class Stmt
+
+class ForStmt : Stmt()
+
+sealed class Expr : Stmt() {
+    object BinExpr : Expr()
+}
+
+fun test(x: Stmt): String =
+        when (x) {
+            is Expr -> "expr"
+            is Stmt -> "stmt"
+        }
+
+fun test2(x: Stmt): String =
+        when (x) {
+            is Expr -> "expr"
+        }
+
+fun test3(x: Expr): String =
+        when (x) {
+            is Stmt -> "stmt"
+        }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTree.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTree.fir.kt
new file mode 100644
index 00000000000..d19eb6011fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTree.fir.kt
@@ -0,0 +1,34 @@
+sealed class Base {
+    sealed class A : Base() {
+        object A1 : A()
+        sealed class A2 : A()
+    }
+    sealed class B : Base() {
+        sealed class B1 : B()
+        object B2 : B()
+    }
+
+    fun foo() = when (this) {
+        is A -> 1
+        is B.B1 -> 2
+        B.B2 -> 3
+        // No else required
+    }
+
+    fun bar() = when (this) {
+        is A -> 1
+        is B.B1 -> 2
+    }
+
+    fun baz() = when (this) {
+        is A -> 1
+        B.B2 -> 3
+        // No else required (no possible B1 instances)
+    }
+
+    fun negated() = when (this) {
+        !is A -> 1
+        A.A1 -> 2
+        is A.A2 -> 3
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTriangleStar.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTriangleStar.fir.kt
new file mode 100644
index 00000000000..68a39439d7c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveOnTriangleStar.fir.kt
@@ -0,0 +1,24 @@
+sealed class A
+sealed class B : A()
+
+class C : B()
+class D : B()
+
+fun test(a: A): Any {
+    return when (a) {
+        is C -> ""
+        is D -> ""
+    }
+}
+
+fun test2(a: A): Any {
+    return when (a) {
+        is B -> ""
+    }
+}
+
+fun test3(a: A): Any {
+    return when (a) {
+        is D -> ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhen.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhen.fir.kt
new file mode 100644
index 00000000000..cd9a104257f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhen.fir.kt
@@ -0,0 +1,16 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        is Sealed.First -> 1
+        is Sealed.NonFirst -> 0
+        // no else required
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenDoubleInner.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenDoubleInner.fir.kt
new file mode 100644
index 00000000000..1a4fc73d191
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenDoubleInner.fir.kt
@@ -0,0 +1,16 @@
+sealed class Sealed() {
+    object First: Sealed()
+    open class NonFirst: Sealed() {
+        object Second: NonFirst()
+        object Third: NonFirst()
+        // It's ALLOWED to inherit Sealed also from here
+        object Fourth: Sealed()
+    }    
+}
+
+fun foo(s: Sealed) = when(s) {
+    Sealed.First -> 1
+    is Sealed.NonFirst -> 2
+    Sealed.NonFirst.Fourth -> 4
+    // no else required
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenMultipleInner.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenMultipleInner.fir.kt
new file mode 100644
index 00000000000..5c46abf6f29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenMultipleInner.fir.kt
@@ -0,0 +1,47 @@
+sealed class Sealed() {
+    object First: Sealed()
+    open class NonFirst: Sealed() {
+        class NonSecond: NonFirst() {
+            object Third: Sealed()
+            class NonThird: Sealed() {
+                object Fourth: NonFirst()
+                class Fifth: Sealed()
+            }    
+        }
+        object Second: Sealed()
+    }    
+}
+
+fun foo(s: Sealed) = when(s) {
+    Sealed.First -> 1
+    is Sealed.NonFirst -> 2
+    Sealed.NonFirst.Second -> 4
+    Sealed.NonFirst.NonSecond.Third -> 6
+    is Sealed.NonFirst.NonSecond.NonThird -> 8
+    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
+    // no else required
+}
+
+fun fooWithElse(s: Sealed) = when(s) {
+    Sealed.First -> 1
+    Sealed.NonFirst.NonSecond.Third -> 6
+    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
+    else -> 0
+}
+
+fun fooWithoutElse(s: Sealed) = when(s) {
+    Sealed.First -> 1
+    is Sealed.NonFirst -> 2
+    Sealed.NonFirst.NonSecond.Third -> 6
+    is Sealed.NonFirst.NonSecond.NonThird -> 8
+    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
+}
+
+fun barWithoutElse(s: Sealed) = when(s) {
+    Sealed.First -> 1
+    is Sealed.NonFirst -> 2
+    Sealed.NonFirst.Second -> 4
+    is Sealed.NonFirst.NonSecond.NonThird -> 8
+    is Sealed.NonFirst.NonSecond.NonThird.Fifth -> 10
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenNegated.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenNegated.fir.kt
new file mode 100644
index 00000000000..1e0f78ef81c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenNegated.fir.kt
@@ -0,0 +1,16 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        is Sealed.First -> 1
+        !is Sealed.First -> 0
+        // no else required
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenNegatedTwice.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenNegatedTwice.fir.kt
new file mode 100644
index 00000000000..949ccc9b67c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenNegatedTwice.fir.kt
@@ -0,0 +1,17 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+    }
+    object Last: Sealed(78)
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        !is Sealed.First -> 1
+        !is Sealed.Last -> 0
+        // no else required
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenOnNestedSealed.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenOnNestedSealed.fir.kt
new file mode 100644
index 00000000000..7e1f8c828a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenOnNestedSealed.fir.kt
@@ -0,0 +1,20 @@
+sealed class Sealed {
+    object First: Sealed()
+    sealed class NonFirst {
+        object Second: NonFirst()
+        object Third: NonFirst()
+        object Fourth: Sealed()
+    }    
+}
+
+fun foo(s: Sealed, nf: Sealed.NonFirst): Int {
+    val si = when(s) {
+        Sealed.First -> 1
+        Sealed.NonFirst.Fourth -> 4
+    }
+    val nfi = when(nf) {
+        Sealed.NonFirst.Second -> 2
+        Sealed.NonFirst.Third -> 3
+    }
+    return si <!UNRESOLVED_REFERENCE!>+<!> nfi
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenOnNullable.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenOnNullable.fir.kt
new file mode 100644
index 00000000000..38c493ca263
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenOnNullable.fir.kt
@@ -0,0 +1,17 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+    }
+}
+
+fun foo(s: Sealed?): Int {
+    return when(s) {
+        is Sealed.First -> 1
+        is Sealed.NonFirst -> 0
+        null -> -1
+        // no else required
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenWithAdditionalMember.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenWithAdditionalMember.fir.kt
new file mode 100644
index 00000000000..1f12821e8ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenWithAdditionalMember.fir.kt
@@ -0,0 +1,18 @@
+sealed class Sealed(val x: Int) {
+    data class Tuple(val x: Int, val y: Int)
+    object First: Sealed(12)
+    open class NonFirst(tuple: Tuple): Sealed(tuple.x) {
+        val y: Int = tuple.y
+        object Second: NonFirst(Tuple(34, 2))
+        object Third: NonFirst(Tuple(56, 3))
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        is Sealed.First -> 1
+        is Sealed.NonFirst -> 0
+        // no else required
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenWithElse.fir.kt b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenWithElse.fir.kt
new file mode 100644
index 00000000000..711f599a637
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/ExhaustiveWhenWithElse.fir.kt
@@ -0,0 +1,15 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        is Sealed.NonFirst -> 0
+        else -> -1
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/Local.fir.kt b/compiler/testData/diagnostics/tests/sealed/Local.fir.kt
new file mode 100644
index 00000000000..f6559a21f25
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/Local.fir.kt
@@ -0,0 +1,13 @@
+sealed class Sealed {
+    object First: Sealed()
+    open class NonFirst: Sealed() {
+        object Second: NonFirst()
+        object Third: NonFirst()
+        fun foo(): Int {
+            val s = object: Sealed() {}
+            class Local: Sealed() {}
+            return s.hashCode()
+        }
+    }
+    val p: Sealed = object: Sealed() {}
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/LocalSealed.fir.kt b/compiler/testData/diagnostics/tests/sealed/LocalSealed.fir.kt
new file mode 100644
index 00000000000..add2fe130d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/LocalSealed.fir.kt
@@ -0,0 +1,3 @@
+fun foo() {
+    sealed class My
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NestedSealed.fir.kt b/compiler/testData/diagnostics/tests/sealed/NestedSealed.fir.kt
new file mode 100644
index 00000000000..a4b0fe5e47b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NestedSealed.fir.kt
@@ -0,0 +1,45 @@
+// See KT-10648: Exhaustiveness check does not work with nested sealed hierarchy
+sealed class Base {
+    sealed class A : Base() {
+        class A1 : A()
+        class A2 : A()
+    }
+    sealed class B : Base() {
+        class B1 : B()
+        class B2 : B()
+    }
+}
+
+fun foo(b: Base) = when (b) {
+    is Base.A -> when(b) {
+        is Base.A.A1 -> 1
+        is Base.A.A2 -> 2
+    }
+    is Base.B -> when(b) {
+        is Base.B.B1 -> 3
+        is Base.B.B2 -> 4
+    }
+}
+
+fun bar(b: Base?) = if (b == null) 0 else when (b) {
+    is Base.A -> when(b) {
+        is Base.A.A1 -> 1
+        is Base.A.A2 -> 2
+    }
+    is Base.B -> when(b) {
+        is Base.B.B1 -> 3
+        is Base.B.B2 -> 4
+    }
+}
+
+fun gav(b: Base?) = when (b) {
+    null -> 0
+    is Base.A -> when(b) {
+        is Base.A.A1 -> 1
+        is Base.A.A2 -> 2
+    }
+    is Base.B -> when(b) {
+        is Base.B.B1 -> 3
+        is Base.B.B2 -> 4
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NeverConstructed.fir.kt b/compiler/testData/diagnostics/tests/sealed/NeverConstructed.fir.kt
new file mode 100644
index 00000000000..b2093a68dc8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NeverConstructed.fir.kt
@@ -0,0 +1,3 @@
+sealed class Base {
+    fun foo() = Base()
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NeverDerivedFromNested.fir.kt b/compiler/testData/diagnostics/tests/sealed/NeverDerivedFromNested.fir.kt
new file mode 100644
index 00000000000..05adf4bfab5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NeverDerivedFromNested.fir.kt
@@ -0,0 +1,9 @@
+class A {
+    sealed class Base
+}
+
+class Derived : A.Base()
+
+fun test() {
+    class DerivedLocal : A.Base()
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NeverEnum.fir.kt b/compiler/testData/diagnostics/tests/sealed/NeverEnum.fir.kt
new file mode 100644
index 00000000000..8317d7a4c34
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NeverEnum.fir.kt
@@ -0,0 +1,6 @@
+sealed enum class SealedEnum {
+    FIRST, 
+    SECOND;
+
+    class Derived: SealedEnum()
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NeverFinal.fir.kt b/compiler/testData/diagnostics/tests/sealed/NeverFinal.fir.kt
new file mode 100644
index 00000000000..13fb5481e51
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NeverFinal.fir.kt
@@ -0,0 +1,3 @@
+final sealed class Base {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/NeverInterface.fir.kt b/compiler/testData/diagnostics/tests/sealed/NeverInterface.fir.kt
new file mode 100644
index 00000000000..d70b4d3f01b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NeverInterface.fir.kt
@@ -0,0 +1,3 @@
+sealed interface Base {
+
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NeverObject.fir.kt b/compiler/testData/diagnostics/tests/sealed/NeverObject.fir.kt
new file mode 100644
index 00000000000..7fb9dd4ce14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NeverObject.fir.kt
@@ -0,0 +1,3 @@
+sealed object Sealed {
+
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NeverOpen.fir.kt b/compiler/testData/diagnostics/tests/sealed/NeverOpen.fir.kt
new file mode 100644
index 00000000000..34e4caa6ed7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NeverOpen.fir.kt
@@ -0,0 +1,3 @@
+open sealed class Base {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhen.fir.kt b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhen.fir.kt
new file mode 100644
index 00000000000..9c5be055bd6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhen.fir.kt
@@ -0,0 +1,14 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        is Sealed.NonFirst -> 0
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenNegated.fir.kt b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenNegated.fir.kt
new file mode 100644
index 00000000000..77cbfbf26c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenNegated.fir.kt
@@ -0,0 +1,14 @@
+sealed class Sealed(val x: Int) {
+    object First: Sealed(12)
+    open class NonFirst(x: Int, val y: Int): Sealed(x) {
+        object Second: NonFirst(34, 2)
+        object Third: NonFirst(56, 3)
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        !is Sealed.NonFirst -> 1
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAdditionalCase.fir.kt b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAdditionalCase.fir.kt
new file mode 100644
index 00000000000..e2d3b79c3c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAdditionalCase.fir.kt
@@ -0,0 +1,22 @@
+sealed class Sealed(val x: Int) {
+    interface ITuple {
+        val x: Int
+        val y: Int
+    }
+    class Tuple(override val x: Int, override val y: Int): ITuple
+    object First: Sealed(12)
+    open class NonFirst(tuple: Tuple): Sealed(tuple.x), ITuple {
+        override val y: Int = tuple.y
+        object Second: NonFirst(Tuple(34, 2))
+        class Third: NonFirst(Tuple(56, 3))
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        is Sealed.First -> 1
+        !is Sealed.ITuple -> 0
+        // else required
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAnyCase.fir.kt b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAnyCase.fir.kt
new file mode 100644
index 00000000000..e9e4eed0755
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAnyCase.fir.kt
@@ -0,0 +1,15 @@
+sealed class Sealed {
+    object First: Sealed()
+    open class NonFirst: Sealed() {
+        object Second: NonFirst()
+        object Third: NonFirst()
+    }
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        is Sealed.First -> 1
+        !is Any -> 0
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/NonPrivateConstructor.fir.kt b/compiler/testData/diagnostics/tests/sealed/NonPrivateConstructor.fir.kt
new file mode 100644
index 00000000000..56541013112
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NonPrivateConstructor.fir.kt
@@ -0,0 +1,7 @@
+sealed class Sealed protected constructor(val x: Int) {
+    object FIRST : Sealed()
+
+    public constructor(): this(42)
+
+    constructor(y: Int, z: Int): this(y + z)
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/NotFinal.fir.kt b/compiler/testData/diagnostics/tests/sealed/NotFinal.fir.kt
new file mode 100644
index 00000000000..0cf7cf13a5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/NotFinal.fir.kt
@@ -0,0 +1,10 @@
+// See KT-9244
+
+sealed class Foo {
+  class Bar : Foo()
+  class Baz : Foo()
+}
+
+// The following warning seems incorrect here
+// "Foo is a final type, and thus a value of the type parameter is predetermined"
+fun <T : Foo> doit(arg: T): T = arg
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/OperationWhen.fir.kt b/compiler/testData/diagnostics/tests/sealed/OperationWhen.fir.kt
new file mode 100644
index 00000000000..c45fa8412f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/OperationWhen.fir.kt
@@ -0,0 +1,20 @@
+sealed class Operation(val left: Int, val right: Int) {
+    abstract fun exec(): Int
+    class Plus(left: Int, right: Int): Operation(left, right) {
+        override fun exec(): Int = left + right
+    }
+    class Minus(left: Int, right: Int): Operation(left, right) {
+        override fun exec(): Int = left - right
+    }
+    class Times(left: Int, right: Int): Operation(left, right) {
+        override fun exec(): Int = left * right
+    }
+    class Slash(left: Int, right: Int): Operation(left, right) {
+        override fun exec(): Int = left / right
+    }
+}
+
+fun priority(op: Operation) = when(op) {
+    is Operation.Plus, is Operation.Minus  -> 1
+    is Operation.Times, is Operation.Slash -> 2
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/RedundantAbstract.fir.kt b/compiler/testData/diagnostics/tests/sealed/RedundantAbstract.fir.kt
new file mode 100644
index 00000000000..4a90ee701d2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/RedundantAbstract.fir.kt
@@ -0,0 +1,3 @@
+abstract sealed class Base {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/TreeWhen.fir.kt b/compiler/testData/diagnostics/tests/sealed/TreeWhen.fir.kt
new file mode 100644
index 00000000000..be3b48e407c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/TreeWhen.fir.kt
@@ -0,0 +1,13 @@
+sealed class Tree {
+    object Empty: Tree()
+    class Leaf(val x: Int): Tree()
+    class Node(val left: Tree, val right: Tree): Tree()
+
+    fun max(): Int {
+        when(this) {
+            is Empty -> return -1
+            is Leaf -> return this.x
+            is Node -> return this.left.max()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/TreeWhenFunctional.fir.kt b/compiler/testData/diagnostics/tests/sealed/TreeWhenFunctional.fir.kt
new file mode 100644
index 00000000000..38c058814d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/TreeWhenFunctional.fir.kt
@@ -0,0 +1,11 @@
+sealed class Tree {
+    object Empty: Tree()
+    class Leaf(val x: Int): Tree()
+    class Node(val left: Tree, val right: Tree): Tree()
+
+    fun max(): Int = when(this) {
+        is Empty -> -1
+        is Leaf  -> this.x
+        is Node  -> this.left.max()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/sealed/TreeWhenFunctionalNoIs.fir.kt b/compiler/testData/diagnostics/tests/sealed/TreeWhenFunctionalNoIs.fir.kt
new file mode 100644
index 00000000000..c2d43bfb3cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/TreeWhenFunctionalNoIs.fir.kt
@@ -0,0 +1,23 @@
+sealed class Tree {
+    object Empty: Tree()
+    class Leaf(val x: Int): Tree()
+    class Node(val left: Tree, val right: Tree): Tree()
+
+    fun max(): Int = when(this) {
+        Empty -> -1
+        is Leaf  -> this.x
+        is Node  -> this.left.max()
+    }
+
+    fun maxIsClass(): Int = when(this) {
+        Empty -> -1
+        Leaf  -> 0
+        is Node  -> this.left.max()
+    }
+
+    fun maxWithElse(): Int = when(this) {
+        is Leaf  -> this.x
+        is Node  -> this.left.max()
+        else -> -1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sealed/WhenOnEmptySealed.fir.kt b/compiler/testData/diagnostics/tests/sealed/WhenOnEmptySealed.fir.kt
new file mode 100644
index 00000000000..9271a1b4474
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/WhenOnEmptySealed.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+sealed class Sealed {
+
+}
+
+fun foo(s: Sealed): Int {
+    return when(s) {
+        // We do not return anything, so else branch must be here
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/sealed/WithInterface.fir.kt b/compiler/testData/diagnostics/tests/sealed/WithInterface.fir.kt
new file mode 100644
index 00000000000..d1b2b3641d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sealed/WithInterface.fir.kt
@@ -0,0 +1,10 @@
+interface Parent
+interface Child : Parent
+
+sealed class Page : Parent {
+  object One : Page(), Child
+  object Two : Page(), Child
+}
+
+// Ok: page is a Parent so it can be easily a Child
+fun test(page: Page): Boolean = page is Child
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/argumentsResolveInBodyAndDelegationCall.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/argumentsResolveInBodyAndDelegationCall.fir.kt
new file mode 100644
index 00000000000..b7444d2bdaf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/argumentsResolveInBodyAndDelegationCall.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B(open val parentProp: Int)
+val global: Int = 1
+class A : B {
+    val myProp: Int = 1
+    override val parentProp = 1
+
+    constructor(x: Int, y: Int = global): <!INAPPLICABLE_CANDIDATE!>super<!>(x + y + global) {
+        foo(x, y, myProp)
+        x + y + myProp + parentProp + super.parentProp
+    }
+    constructor(x: Double, y: Int): this(x.toInt() + y, x.toInt() * y) {
+        foo(x.toInt(), y, myProp)
+        x + y + myProp + parentProp + super.parentProp
+    }
+    constructor(x: String, y: Int): <!INAPPLICABLE_CANDIDATE!>super<!>(x) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(x, y, myProp)
+        x + y + myProp + parentProp + super.parentProp
+    }
+    constructor(x: B, y: Int = <!UNRESOLVED_REFERENCE!>global2<!>): <!INAPPLICABLE_CANDIDATE!>this<!>("", x) {
+        x.parentProp + y + myProp + parentProp + super.parentProp
+    }
+
+    fun foo(x: Int, y: Int, z: Int) = x
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/classInitializersWithoutPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/classInitializersWithoutPrimary.fir.kt
new file mode 100644
index 00000000000..30c8fe5f432
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/classInitializersWithoutPrimary.fir.kt
@@ -0,0 +1,4 @@
+class A {
+    constructor()
+    init {}
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/companionObjectScope.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/companionObjectScope.fir.kt
new file mode 100644
index 00000000000..4c912288c9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/companionObjectScope.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    companion object {
+        fun foo(): Int = 1
+        val prop = 2
+        val C = 3
+    }
+    object B {
+        fun bar(): Int = 4
+        val prop = 5
+    }
+    object C {
+    }
+
+    constructor(x: Int)
+    constructor() : this(foo() + prop + B.bar() + B.prop <!INAPPLICABLE_CANDIDATE!>+<!> C)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/constructorCallType.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/constructorCallType.fir.kt
new file mode 100644
index 00000000000..84046fb59e6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/constructorCallType.fir.kt
@@ -0,0 +1,28 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// NI_EXPECTED_FILE
+class A(x: Int) {
+    constructor(x: Double): this(1)
+    constructor(x: String): this(1)
+}
+val x1: A = A(1)
+val x2: A = A(1.0)
+val x3: A = A("abc")
+
+class B<R> {
+    constructor(x: String)
+    constructor(x: R)
+}
+
+val y1: B<Int> = B(1)
+val y2: B<Int> = B("")
+val y3: B<Int> = B<Int>(1)
+val y4: B<Int> = B<Int>("")
+
+val y5: B<String> = <!INAPPLICABLE_CANDIDATE!>B<!><String>(1)
+val y6: B<String> = B<String>("")
+val y7: B<String> = B(1)
+val y8: B<String> = B("")
+
+val y9 = B(1)
+val y10 = B("")
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/constructorInObject.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/constructorInObject.fir.kt
new file mode 100644
index 00000000000..6ed018c439c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/constructorInObject.fir.kt
@@ -0,0 +1,20 @@
+object A {
+    constructor()
+    init {}
+}
+
+enum class B {
+    X() {
+        constructor()
+    }
+}
+
+class C {
+    companion object {
+        constructor()
+    }
+}
+
+val anonObject = object {
+    <!CONSTRUCTOR_IN_OBJECT!>constructor()<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/constructorInTrait.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/constructorInTrait.fir.kt
new file mode 100644
index 00000000000..08d09a765ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/constructorInTrait.fir.kt
@@ -0,0 +1,3 @@
+interface A {
+    constructor()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/ctrsAnnotationResolve.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/ctrsAnnotationResolve.fir.kt
new file mode 100644
index 00000000000..126437ad8ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/ctrsAnnotationResolve.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+annotation class Ann1
+annotation class Ann2(val x: Int)
+
+class A {
+    @Ann1
+    constructor()
+    @Ann2
+    constructor(x1: Int)
+    @Ann2(2)
+    constructor(x1: Int, x2: Int)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/cyclicDelegationCalls.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/cyclicDelegationCalls.fir.kt
new file mode 100644
index 00000000000..f96d9d0191b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/cyclicDelegationCalls.fir.kt
@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A1 {
+    constructor(): this()
+}
+
+class A2(x: Byte) {
+    constructor(x1: Int): this(x1, 1)
+    constructor(x1: Int, x2: Int): this(x1, x2, 2)
+    constructor(x1: Int, x2: Int, x3: Int): this(x1)
+
+    // delegating to previously declared cycle
+    constructor(x1: Double): this(1)
+
+
+    // delegating to cycle declared after
+    constructor(x1: String): this(1L)
+
+    constructor(x1: Long): this(x1, 1L)
+    constructor(x1: Long, x2: Long): this(x1, x2, 2L)
+    constructor(x1: Long, x2: Long, x3: Long): this(x1)
+
+    // no cycle, just call to primary constuctor
+    constructor(x1: Double, x2: Double): this(x1, x2, 1.0)
+    constructor(x1: Double, x2: Double, x3: Double): this(x1, x2, x3, 1.0)
+    constructor(x1: Double, x2: Double, x3: Double, x4: Double): this(1.toByte())
+
+    constructor(): this("x", "y")
+
+    constructor(x1: String, x2: String): this(x1, x2, "")
+    constructor(x1: String, x2: String, x3: String): this(x1, x2)
+}
+
+open class B(x: Byte)
+class A : B {
+    // no cycle, just call to super constuctor
+    constructor(x1: Double, x2: Double): this(x1, x2, 1.0)
+    constructor(x1: Double, x2: Double, x3: Double): this(x1, x2, x3, 1.0)
+    constructor(x1: Double, x2: Double, x3: Double, x4: Double): <!INAPPLICABLE_CANDIDATE!>super<!>(1.toByte())
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/dataClasses.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/dataClasses.fir.kt
new file mode 100644
index 00000000000..5c47d816dbc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/dataClasses.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+data class A1(val x: String) {
+    constructor(): this("")
+}
+
+data class A2(val y: String, val z: Int) {
+    constructor(x: String): this(x, 0)
+}
+
+data class A3 {
+    constructor()
+}
+
+data class A4 internal constructor()
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/dataFlowInDelegationCall.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/dataFlowInDelegationCall.fir.kt
new file mode 100644
index 00000000000..e49226fe865
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/dataFlowInDelegationCall.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    constructor(x: Any, y: Any, z: Any)
+    constructor(x: String?, y: String?): this(x!!, x.length.toString() + y!!, "") {
+        x.length + y.length
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/delegationByWithoutPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/delegationByWithoutPrimary.fir.kt
new file mode 100644
index 00000000000..6058e862c1e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/delegationByWithoutPrimary.fir.kt
@@ -0,0 +1,6 @@
+interface A
+class AImpl : A
+
+class B : A by AImpl() {
+    constructor()
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/enums.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/enums.fir.kt
new file mode 100644
index 00000000000..b8e60603d80
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/enums.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+enum class A {
+    W(1), X(1, 2), Y(3.0), Z(""), E();
+
+    constructor()
+    constructor(x: Int)
+    constructor(x: Int, y: Int): this(x+y)
+    constructor(x: Double): this(x.toInt(), 1)
+    constructor(x: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, 1)
+}
+
+enum class B(x: Int) {
+    W(1), X(1, 2), Y(3.0), Z("");
+
+    constructor(x: Int, y: Int): this(x+y)
+    constructor(x: Double): this(x.toInt(), 1)
+    constructor(x: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, 1)
+}
+
+enum class C {
+    EMPTY(); // may be we should avoid explicit call here
+    constructor()
+}
+
+enum class D(val prop: Int) {
+    X(123) {
+        override fun f() = 1
+    },
+    Y() {
+        override fun f() = prop
+    },
+    Z("abc") {
+        override fun f() = prop
+    };
+
+    constructor(): this(1)
+    constructor(x: String): this(x.length)
+
+    abstract fun f(): Int
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/errorsOnEmptyDelegationCall.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/errorsOnEmptyDelegationCall.fir.kt
new file mode 100644
index 00000000000..f3baa777222
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/errorsOnEmptyDelegationCall.fir.kt
@@ -0,0 +1,42 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B0(x: Int)
+
+class A0 : B0 {
+    constructor()
+    constructor(x: Int) : super()
+}
+
+// --------------------------
+
+open class B1 {
+    constructor(x: Int = 1)
+    constructor()
+}
+
+class A1 : B1 {
+    constructor()
+    constructor(x: Int) : super()
+}
+
+// --------------------------
+
+open class B2 {
+    constructor(x: Int)
+    constructor(x: String)
+}
+
+class A2 : B2 {
+    constructor()
+    constructor(x: Int) : super()
+}
+
+// --------------------------
+
+open class B3 {
+    private constructor()
+}
+
+class A3 : B3 {
+    constructor()
+    constructor(x: Int) : super()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/expectedPrimaryConstructorCall.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/expectedPrimaryConstructorCall.fir.kt
new file mode 100644
index 00000000000..71ffad646e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/expectedPrimaryConstructorCall.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A(x: Int) {
+    constructor()
+}
+open class B(x: Int)
+class C(x: Int) : B(x) {
+    constructor(): super(1)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/generics.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/generics.fir.kt
new file mode 100644
index 00000000000..8dc957d4d5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/generics.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNREACHABLE_CODE
+open class B<T>(x: T, y: T) {
+    constructor(x: T): this(x, x)
+    constructor(): this(null!!, null!!)
+}
+
+class A0 : B<String?> {
+    constructor()
+    constructor(x: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x)
+    constructor(x: String, y: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+}
+
+class A1<R> : B<R> {
+    constructor()
+    constructor(x: R): <!INAPPLICABLE_CANDIDATE!>super<!>(x)
+    constructor(x: R, y: R): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+}
+
+class A2<R> {
+    constructor(t: R, i: Int) : this(i, 1)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/generics2.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/generics2.fir.kt
new file mode 100644
index 00000000000..e39d3bb67b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/generics2.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+open class B<R1, R2>(x: R1, y: R2)
+
+class A0<T1, T2> {
+    constructor(x: T1, y: T2): this(x, y)
+
+    constructor(x: T1, y: T2, z: T2): this(x, 1) // ok, delegates to constructor(x: T1, y: Int)
+
+    constructor(x: T1, y: Int): this(x, "")
+    constructor(x: T1): this(x, 1)
+    constructor(x: T1, y: T2, z: String): this(y, x)
+}
+
+class A1<T1, T2> : B<T1, T2> {
+    constructor(x: T1, y: T2): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+    constructor(x: T1, y: Int): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+    constructor(x: T1, y: T1, z: T1): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+}
+
+class A2<T1, T2> : B<T1, Int> {
+    constructor(x: T1, y: T2): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+    constructor(x: T1, y: Int): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+    constructor(x: T1, y: T1, z: T1): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+    constructor(x: T1, y: T2, z: String): <!INAPPLICABLE_CANDIDATE!>super<!>(y, 1)
+}
+
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/generics3.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/generics3.fir.kt
new file mode 100644
index 00000000000..d5466da6c22
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/generics3.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B<X, Y : X> {
+    constructor(x: X, y: Y)
+    constructor(x: X, s: String)
+    constructor(y: Y, i: Int) : this(y, "")
+}
+
+class A<T1, T2 : T1> : B<T1, T2> {
+    constructor(x: T1, y: T2): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+    constructor(x: T2, y: T2, z: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, y)
+
+    constructor(x: T2, z: String, z1: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, "")
+    constructor(x: T2, z: String, z1: String, z2: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, 1)
+    constructor(x: T1, z: String, z1: String, z2: String, z3: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, "")
+    constructor(x: T1, z: String, z1: String, z2: String, z3: String, z4: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, 1)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseGenericFromInnerExtendingSameBase.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseGenericFromInnerExtendingSameBase.fir.kt
new file mode 100644
index 00000000000..2153e3f94e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseGenericFromInnerExtendingSameBase.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class Base<T>(p: Any?) {
+    fun foo1(t: T) {}
+}
+
+class D: Base<Int>("") {
+    inner class B : Base<String> {
+        constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(foo1(""))
+        constructor(x: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(foo1(1))
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseGenericFromInnerExtendingSameBase2.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseGenericFromInnerExtendingSameBase2.fir.kt
new file mode 100644
index 00000000000..f16da07a325
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseGenericFromInnerExtendingSameBase2.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class Base<T>(p: Any?) {
+    fun foo1(t: T) {}
+}
+
+class D: Base<Int>(1) {
+    inner class B : Base<Int> {
+        constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(foo1(1))
+        constructor(x: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(this@B.foo1(1))
+        constructor(x: Int, y: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(this@D.foo1(1))
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseWithSameExtension.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseWithSameExtension.fir.kt
new file mode 100644
index 00000000000..ba8a1560feb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessBaseWithSameExtension.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class Base(p: Any?) {
+    fun foo1() {}
+}
+
+fun Base.foo() {
+    class B : Base {
+        constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(foo1())
+        constructor(x: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(this@foo.foo1())
+        constructor(x: Int, y: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(this@B.foo1())
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessGenericBaseWithSameExtension.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessGenericBaseWithSameExtension.fir.kt
new file mode 100644
index 00000000000..d0f53ae4f08
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/accessGenericBaseWithSameExtension.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class Base<T>(p: Any?) {
+    fun foo1(t: T) {}
+}
+
+fun Base<Int>.foo() {
+    class B : Base<String> {
+        constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(foo1(""))
+        constructor(x: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(foo1(1))
+        constructor(x: Int, y: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(this@foo.foo1(12))
+        constructor(x: Int, y: Int, z: Int) : <!INAPPLICABLE_CANDIDATE!>super<!>(this@B.foo1(""))
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/innerInstanceCreation.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/innerInstanceCreation.fir.kt
new file mode 100644
index 00000000000..76c24c1b31d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/innerInstanceCreation.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(x: Outer) = 1
+class Outer {
+    inner class Inner {
+        val prop = 1
+    }
+
+    constructor(x: Int)
+    constructor(x: Int, y: Int, z: Int = x + Inner().prop + this.Inner().prop) :
+        this(x + Inner().prop + this.Inner().prop)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/lambdaAsArgument.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/lambdaAsArgument.fir.kt
new file mode 100644
index 00000000000..1a01acc6fb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/lambdaAsArgument.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun A.foobar() = 3
+
+class A {
+    fun foo() = 1
+    constructor(x: () -> Int)
+    constructor() : this(
+            {
+                foo() +
+                this.foo() +
+                this@A.foo() +
+                foobar()
+            })
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/memberFunAccess.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/memberFunAccess.fir.kt
new file mode 100644
index 00000000000..f67d2a5ec49
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/memberFunAccess.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    fun foo() = 1
+    constructor(x: Int)
+    constructor(x: Int, y: Int, z: Int = x + foo() + this.foo()) :
+        this(x + foo() + this.foo())
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/objectLiteralAsArgument.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/objectLiteralAsArgument.fir.kt
new file mode 100644
index 00000000000..dd0522dc156
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/objectLiteralAsArgument.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun A.foobar() = 3
+
+class A {
+    fun foo() = 1
+    constructor(x: Any?)
+    constructor() : this(object {
+        fun bar() = foo() + this@A.foo() +
+                    foobar() + super@A.hashCode()
+    })
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/objectLiteralAsDefaultValueParameter.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/objectLiteralAsDefaultValueParameter.fir.kt
new file mode 100644
index 00000000000..3c312d74e40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/objectLiteralAsDefaultValueParameter.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun A.foobar() = 3
+
+class A {
+    fun foo() = 1
+    constructor( x: Any = object {
+        fun bar() = foo() + this@A.foo() +
+                    foobar()
+    })
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/operatorCall.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/operatorCall.fir.kt
new file mode 100644
index 00000000000..4fe0347386c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/operatorCall.fir.kt
@@ -0,0 +1,13 @@
+open class C(val x: Int)
+
+class D : C {
+    constructor() : <!INAPPLICABLE_CANDIDATE!>super<!>(
+            {
+                val s = ""
+                s()
+                ""()
+                42
+            }())
+
+    operator fun String.invoke() { }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/passingInstance.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/passingInstance.fir.kt
new file mode 100644
index 00000000000..8fe392bd885
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/passingInstance.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(x: A) = 1
+
+class A {
+    constructor(x: Int)
+    constructor(x: Int, y: Int, z: Int = x + foo(this) + foo(this@A)) :
+        this(x + foo(this) + foo(this@A))
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/propertyAccess.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/propertyAccess.fir.kt
new file mode 100644
index 00000000000..73c5b28e651
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/propertyAccess.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    val prop = 1
+    constructor(x: Int)
+    constructor(x: Int, y: Int, z: Int = x + prop + this.prop) :
+        this(x + prop + this.prop)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/propertyAccessUnitialized.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/propertyAccessUnitialized.fir.kt
new file mode 100644
index 00000000000..d6b566fc562
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/propertyAccessUnitialized.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B(x: Int)
+class A : B {
+    val prop = 1
+    constructor(x: Int, y: Int = x + prop + this.prop) :
+        <!INAPPLICABLE_CANDIDATE!>super<!>(x + prop + this.prop)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccess.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccess.fir.kt
new file mode 100644
index 00000000000..ba91b894ba4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccess.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B(x: Int) {
+    fun foo() = 1
+}
+class A : B {
+    constructor(x: Int, y: Int = x + foo() + this.foo() + super.foo()) :
+        <!INAPPLICABLE_CANDIDATE!>super<!>(x + foo() + this.foo() + super.foo())
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccessOverriden.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccessOverriden.fir.kt
new file mode 100644
index 00000000000..3e7a6494ba1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superFunAccessOverriden.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B(x: Int) {
+    open fun foo() = 1
+}
+class A : B {
+    override fun foo() = 2
+    constructor(x: Int, y: Int = x + foo() + this.foo() + super.foo()) :
+        <!INAPPLICABLE_CANDIDATE!>super<!>(x + foo() + this.foo() + super.foo())
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superPropertyAccess.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superPropertyAccess.fir.kt
new file mode 100644
index 00000000000..9c5d9ee7b9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/superPropertyAccess.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B(val prop: Int)
+class A : B {
+    constructor(x: Int, y: Int = x + prop + this.prop + super.prop) :
+        <!INAPPLICABLE_CANDIDATE!>super<!>(x + prop + this.prop + super.prop)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/thisAsExtensionReceiver.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/thisAsExtensionReceiver.fir.kt
new file mode 100644
index 00000000000..67d31be0d8a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/thisAsExtensionReceiver.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun A.foobar() = 1
+val A.prop: Int get() = 2
+
+class A {
+    constructor(x: Int)
+    constructor() : this(
+            foobar() +
+            this.foobar() +
+            prop +
+            this.prop +
+            this@A.prop
+    )
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/usingOuterInstance.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/usingOuterInstance.fir.kt
new file mode 100644
index 00000000000..2ae3abd1d32
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/usingOuterInstance.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(x: Outer) = 1
+class Outer {
+    inner class Inner {
+        constructor(x: Int)
+        constructor(x: Int, y: Int, z: Int = x + foo(this@Outer)) : this(x + foo(this@Outer))
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/usingOuterProperty.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/usingOuterProperty.fir.kt
new file mode 100644
index 00000000000..f429be3cf36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerCallChecker/usingOuterProperty.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class Outer {
+    val prop = 1
+    inner class Inner {
+        constructor(x: Int)
+        constructor(x: Int, y: Int, z: Int = x + prop + this@Outer.prop) : this(x + prop + this@Outer.prop)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/headerSupertypeInitialization.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/headerSupertypeInitialization.fir.kt
new file mode 100644
index 00000000000..eb42f37c72a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/headerSupertypeInitialization.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B(x: Int)
+class A : B(1) {
+    constructor(): super(1)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/implicitSuperCallErrorsIfPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/implicitSuperCallErrorsIfPrimary.fir.kt
new file mode 100644
index 00000000000..479505b025f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/implicitSuperCallErrorsIfPrimary.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class A(p1: String)
+
+class B() : A("") {
+    constructor(s: String) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/initializationFromOtherInstance.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/initializationFromOtherInstance.fir.kt
new file mode 100644
index 00000000000..783a39e61ab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/initializationFromOtherInstance.fir.kt
@@ -0,0 +1,15 @@
+class A {
+    val x: Int
+    val y: Int
+    constructor(x: Int, y: Int) {
+        this.x = x
+        this.y = y
+    }
+    constructor(other: A) {
+        x = other.x
+        y = other.y
+    }
+}
+class A1(val x: Int, val y: Int) {
+    constructor(other: A1): this(other.x, other.y)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/kt6992.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/kt6992.fir.kt
new file mode 100644
index 00000000000..e97067195db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/kt6992.fir.kt
@@ -0,0 +1,3 @@
+class X<T>(val t: T) {
+    constructor(t: String): this(t)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/kt6993.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/kt6993.fir.kt
new file mode 100644
index 00000000000..9b32c097368
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/kt6993.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+class X<T>(val t: T) {
+    constructor(t: T, i: Int) : this(i)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/kt6994.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/kt6994.fir.kt
new file mode 100644
index 00000000000..f7e886bc963
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/kt6994.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class X<T> {
+    constructor(t: T, i: Int): this(i, 1)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/lambdaInDelegation.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/lambdaInDelegation.fir.kt
new file mode 100644
index 00000000000..c89b547890c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/lambdaInDelegation.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A<T1, T2> {
+    constructor(block: (T1) -> T2)
+    constructor(x: T2): this({ x })
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/nestedExtendsInner.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/nestedExtendsInner.fir.kt
new file mode 100644
index 00000000000..a9321da314d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/nestedExtendsInner.fir.kt
@@ -0,0 +1,7 @@
+class A {
+    open inner class Inner
+
+    class Nested : Inner {
+        constructor()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/noDefaultIfEmptySecondary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/noDefaultIfEmptySecondary.fir.kt
new file mode 100644
index 00000000000..8cacea8d87e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/noDefaultIfEmptySecondary.fir.kt
@@ -0,0 +1,4 @@
+// do not report generate empty synthetic constructor by primary as it leads to CONFLICTING_JVM_DECLARATIONS
+class A(val x: Int = 1, val y: Int = 2) {
+    constructor(): this(0, 0)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/noPrimaryConstructor.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/noPrimaryConstructor.fir.kt
new file mode 100644
index 00000000000..c2b72c83e13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/noPrimaryConstructor.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    constructor(x: Int)
+}
+
+val x = <!INAPPLICABLE_CANDIDATE!>A<!>()
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/noSupertypeInitWithSecondaryConstructors.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/noSupertypeInitWithSecondaryConstructors.fir.kt
new file mode 100644
index 00000000000..7b5fe15c5e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/noSupertypeInitWithSecondaryConstructors.fir.kt
@@ -0,0 +1,6 @@
+open class B
+interface C
+interface D
+class A : C, B, D {
+    constructor()
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/propertyInitializationWithPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/propertyInitializationWithPrimary.fir.kt
new file mode 100644
index 00000000000..81e856b0233
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/propertyInitializationWithPrimary.fir.kt
@@ -0,0 +1,33 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A(val w: Char) {
+    val x: Int
+    var y: Int
+    val z: Int
+    val v = -1
+
+    val uninitialized: Int
+    val overinitialized: Int
+
+    constructor(): this('a') {
+        y = 1
+
+        overinitialized = 2
+        uninitialized = 3
+    }
+
+    // anonymous
+    init {
+        x = 4
+        z = 5
+        overinitialized = 6
+    }
+
+    constructor(a: Int): this('b') {
+        y = 7
+    }
+
+    // anonymous
+    init {
+        y = 8
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/propertyInitializationWithoutPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/propertyInitializationWithoutPrimary.fir.kt
new file mode 100644
index 00000000000..b484ac7f7bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/propertyInitializationWithoutPrimary.fir.kt
@@ -0,0 +1,39 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    val x: Int
+    var y: Int
+    val z: Int
+    val v = -1
+
+    val uninitialized: Int
+    val overinitialized: Int
+
+    constructor() {
+        x = 1
+        y = 2
+
+        overinitialized = 3
+        uninitialized = 4
+    }
+
+    constructor(a: Int): super() {
+        x = 5
+        y = 6
+    }
+
+    constructor(x: String): this() {
+        y = 7
+        uninitialized = 8
+    }
+
+    //anonymous
+    init {
+        z = 9
+        overinitialized = 10
+    }
+
+    // anonymous
+    init {
+        y = 12
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/redeclarations.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/redeclarations.fir.kt
new file mode 100644
index 00000000000..b4275c2bd23
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/redeclarations.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A(x: String = "", y: String = "") {
+    constructor(x: String, y: String): this(x, y)
+    constructor(): this("", "")
+    constructor(): this("", "")
+}
+
+class B {
+    constructor(x: Int)
+}
+
+fun B(x: Int) {}
+
+class Outer {
+    class A(x: String = "", y: String = "") {
+        constructor(x: String, y: String): this(x, y)
+        constructor(): this("", "")
+        constructor(): this("", "")
+    }
+
+    class B {
+        constructor(x: Int)
+    }
+
+    fun B(x: Int) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/redeclarationsOfConstructorsIgnored.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/redeclarationsOfConstructorsIgnored.fir.kt
new file mode 100644
index 00000000000..b5b147b0085
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/redeclarationsOfConstructorsIgnored.fir.kt
@@ -0,0 +1,11 @@
+class A
+class A {
+    constructor()
+}
+
+class B
+class Outer {
+    class B {
+        constructor()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/reportResolutionErrorOnImplicitOnce.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/reportResolutionErrorOnImplicitOnce.fir.kt
new file mode 100644
index 00000000000..85667e1cc22
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/reportResolutionErrorOnImplicitOnce.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class A(p1: String, p2: String, p3: String, p4: String, p5: String)
+
+class B : A {
+    constructor(s: String)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/resolvePropertyInitializerWithoutPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/resolvePropertyInitializerWithoutPrimary.fir.kt
new file mode 100644
index 00000000000..c49f6814c5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/resolvePropertyInitializerWithoutPrimary.fir.kt
@@ -0,0 +1,4 @@
+class A {
+    val prop: Int = ""
+    constructor()
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/return.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/return.fir.kt
new file mode 100644
index 00000000000..44f330699d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/return.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+class A {
+    init {
+        return
+        return 1
+    }
+    constructor() {
+        if (1 == 1) {
+            return
+            return 1
+        }
+        return
+        return foo()
+    }
+
+    fun foo(): Int = 1
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/superAnyNonEmpty.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/superAnyNonEmpty.fir.kt
new file mode 100644
index 00000000000..28338060b30
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/superAnyNonEmpty.fir.kt
@@ -0,0 +1,4 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    constructor(): <!INAPPLICABLE_CANDIDATE!>super<!>(1)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/superSecondaryNonExisting.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/superSecondaryNonExisting.fir.kt
new file mode 100644
index 00000000000..76db3f69e6d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/superSecondaryNonExisting.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class B(x: Double) {
+    constructor(x: Int): this(1.0)
+    constructor(x: String): this(1.0)
+}
+interface C
+class A : B, C {
+    constructor(): <!INAPPLICABLE_CANDIDATE!>super<!>(' ')
+    constructor(x: Int)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/thisNonExisting.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/thisNonExisting.fir.kt
new file mode 100644
index 00000000000..38fda4d75df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/thisNonExisting.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+class A {
+    constructor(x: Int) {}
+    constructor(x: String) {}
+    constructor(): <!INAPPLICABLE_CANDIDATE!>this<!>('a') {}
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/unreachableCode.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/unreachableCode.fir.kt
new file mode 100644
index 00000000000..34d183bf40d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/unreachableCode.fir.kt
@@ -0,0 +1,38 @@
+class A0 {
+    val x: Int
+    constructor() {
+        if (1 == 1) {
+            return
+        }
+        x = 1
+    }
+    constructor(arg: Int) {
+        x = arg
+    }
+}
+
+class A1 {
+    val x: Int
+    constructor() {
+        if (1 == 1) {
+            return
+        } else null!!
+        x = 1
+    }
+}
+
+class A2 {
+    val x: Int
+    constructor() {
+        if (1 == 1) {
+            x = 1
+            return
+        }
+        else {
+            x = 2
+        }
+    }
+    constructor(arg: Int) {
+        x = arg
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/useOfPropertiesWithPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/useOfPropertiesWithPrimary.fir.kt
new file mode 100644
index 00000000000..17b476a0238
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/useOfPropertiesWithPrimary.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A(val w: Int) {
+    val x: Int
+    val useUnitialized = x +
+                         y +
+                         v
+    var y: Int
+    val v = -1
+    val useInitialized = useUnitialized + v + w
+
+    val uninitialized: Int
+
+    constructor(): this(1) {
+        x + y + v + uninitialized + w
+    }
+
+    // anonymous
+    init {
+        x + y + v + uninitialized + w
+        x = 1
+        x + y + v + uninitialized + w
+    }
+
+    // anonymous
+    init {
+        x + y + v + uninitialized + w
+        y = 7
+        x + y + v + uninitialized + w
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/useOfPropertiesWithoutPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/useOfPropertiesWithoutPrimary.fir.kt
new file mode 100644
index 00000000000..e99f7fa2722
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/useOfPropertiesWithoutPrimary.fir.kt
@@ -0,0 +1,46 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    val x: Int
+    val useUnitialized = x + // reported on each secondary constructor
+                         y +
+                         v
+    var y: Int
+    val v = -1
+
+    val useInitialized = useUnitialized + v
+
+    val uninitialized: Int
+
+    constructor() {
+        x = 1
+        y = 2
+
+        x + y + v + uninitialized
+
+        uninitialized = 3
+
+        x + y + v + uninitialized
+    }
+
+    constructor(a: Int): super() {
+        x + y + v + uninitialized
+        x = 4
+        y = 5
+
+        x + y + v + uninitialized
+    }
+
+    constructor(x: String): this() {
+        x + y + v + uninitialized
+    }
+
+    //anonymous
+    init {
+        y
+    }
+
+    // anonymous
+    init {
+        y = 9
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/valOrValAndModifiersInCtr.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/valOrValAndModifiersInCtr.fir.kt
new file mode 100644
index 00000000000..c922826f602
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/valOrValAndModifiersInCtr.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    constructor(
+        val x: Int, y: Int,
+        var z: Int,
+        public a: Int)
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/varargsInDelegationCallToPrimary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/varargsInDelegationCallToPrimary.fir.kt
new file mode 100644
index 00000000000..8dd2ca4f47f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/varargsInDelegationCallToPrimary.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun <T> array(vararg x: T): Array<T> = null!!
+
+open class B(vararg y: String) {
+    constructor(x: Int): <!INAPPLICABLE_CANDIDATE!>this<!>(x.toString(), *array("1"), "2")
+}
+
+class A : B {
+    constructor(x: String, y: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, *array("3"), y)
+    constructor(x: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x)
+    constructor(): super()
+}
diff --git a/compiler/testData/diagnostics/tests/secondaryConstructors/varargsInDelegationCallToSecondary.fir.kt b/compiler/testData/diagnostics/tests/secondaryConstructors/varargsInDelegationCallToSecondary.fir.kt
new file mode 100644
index 00000000000..1baecabc09f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/secondaryConstructors/varargsInDelegationCallToSecondary.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun <T> array(vararg x: T): Array<T> = null!!
+
+open class B(x: Int) {
+    constructor(vararg y: String): this(y[0].length)
+}
+
+class A : B {
+    constructor(x: String, y: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x, *array("q"), y)
+    constructor(x: String): <!INAPPLICABLE_CANDIDATE!>super<!>(x)
+    constructor(): super()
+}
+
+val b1 = B()
+val b2 = B("1", "2", "3")
+val b3 = <!INAPPLICABLE_CANDIDATE!>B<!>("1", *array("2", "3"), "4")
+val b4 = B(1)
diff --git a/compiler/testData/diagnostics/tests/senselessComparison/noExplicitType.fir.kt b/compiler/testData/diagnostics/tests/senselessComparison/noExplicitType.fir.kt
new file mode 100644
index 00000000000..db1e3857bcb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/senselessComparison/noExplicitType.fir.kt
@@ -0,0 +1,15 @@
+fun readLine() = "x"
+
+fun foo() {
+    var line = ""
+
+    while (line != null) {
+        line = readLine()
+
+        if (line != null) {
+            bar()
+        }
+    }
+}
+
+fun bar() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/senselessComparison/parenthesized.fir.kt b/compiler/testData/diagnostics/tests/senselessComparison/parenthesized.fir.kt
new file mode 100644
index 00000000000..df6def7435a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/senselessComparison/parenthesized.fir.kt
@@ -0,0 +1,23 @@
+fun testEquals(x: Int) {
+    if (x == null) {}
+    if (x == (null)) {}
+    if (x == foo@ null) {}
+}
+
+fun testEqualsFlipped(x: Int) {
+    if (null == x) {}
+    if ((null) == x) {}
+    if (foo@ null == x) {}
+}
+
+fun testNotEquals(x: Int) {
+    if (x != null) {}
+    if (x != (null)) {}
+    if (x != foo@ null) {}
+}
+
+fun testNotEqualsFlipped(x: Int) {
+    if (null != x) {}
+    if ((null) != x) {}
+    if (foo@ null != x) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowLambdaParameter.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowLambdaParameter.fir.kt
new file mode 100644
index 00000000000..611cba7c02b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowLambdaParameter.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo1(i: (Int) -> Unit) {}
+fun foo2(i: (Int, Int) -> Unit) {}
+fun foo3(i: (Pair) -> Unit) {}
+
+fun bar(x: Int, y: Int) {
+    foo1 { x -> x }
+    foo2 { x: Int, y: Int -> x + y }
+    foo3 { (x, y) -> x + y }
+}
+
+data class Pair(val a: Int, val b: Int)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowMultiDeclarationWithFunParameter.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowMultiDeclarationWithFunParameter.fir.kt
new file mode 100644
index 00000000000..07545f7fd7a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowMultiDeclarationWithFunParameter.fir.kt
@@ -0,0 +1,14 @@
+class A {
+    operator fun component1() = 42
+    operator fun component2() = 42
+}
+
+fun foo(a: A, c: Int) {
+    val (a, b) = a
+    val arr = Array(2) { A() }
+    for ((c, d) in arr)  {
+
+    }
+
+    val e = a.toString() + b + c
+}
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowParameterInFunctionBody.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowParameterInFunctionBody.fir.kt
new file mode 100644
index 00000000000..8b55c6d58ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowParameterInFunctionBody.fir.kt
@@ -0,0 +1,4 @@
+fun f(p: Int): Int {
+    val p = 2
+    return p
+}
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowParameterInNestedBlockInFor.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowParameterInNestedBlockInFor.fir.kt
new file mode 100644
index 00000000000..1b2cec3f6e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowParameterInNestedBlockInFor.fir.kt
@@ -0,0 +1,7 @@
+fun f(i: Int) {
+    for (j in 1..100) {
+        {
+            var i = 12
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInClosure.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInClosure.fir.kt
new file mode 100644
index 00000000000..6490b74f72d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInClosure.fir.kt
@@ -0,0 +1,3 @@
+val i = 17
+
+val f: () -> Int = { var i = 17; i }
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInFor.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInFor.fir.kt
new file mode 100644
index 00000000000..e0d4766e89f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInFor.fir.kt
@@ -0,0 +1,11 @@
+class RedefinePropertyInFor() {
+
+    var i = 1
+    
+    fun ff() {
+        for (i in 0..10) {
+        }
+    }
+
+}
+
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInFunction.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInFunction.fir.kt
new file mode 100644
index 00000000000..cacf415e65e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowPropertyInFunction.fir.kt
@@ -0,0 +1,10 @@
+class RedefinePropertyInFunction() {
+
+    var i = 17
+    
+    fun f(): Int {
+        var i = 18
+        return i
+    }
+
+}
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInFor.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInFor.fir.kt
new file mode 100644
index 00000000000..20a792522e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInFor.fir.kt
@@ -0,0 +1,6 @@
+fun ff(): Int {
+    var i = 1
+    for (i in 0..10) {
+    }
+    return i
+}
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedBlock.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedBlock.fir.kt
new file mode 100644
index 00000000000..8346a2e57e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedBlock.fir.kt
@@ -0,0 +1,7 @@
+fun ff(): Int {
+    var i = 1
+    {
+        val i = 2
+    }
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedClosure.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedClosure.fir.kt
new file mode 100644
index 00000000000..80db73b0a0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedClosure.fir.kt
@@ -0,0 +1,5 @@
+fun f(): Int {
+    var i = 17
+    { var i = 18 }
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedClosureParam.fir.kt b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedClosureParam.fir.kt
new file mode 100644
index 00000000000..127cef7c3f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/ShadowVariableInNestedClosureParam.fir.kt
@@ -0,0 +1,5 @@
+fun ff(): Int {
+    var i = 1
+    { i: Int -> i }
+    return i
+}
diff --git a/compiler/testData/diagnostics/tests/shadowing/noNameShadowingForSimpleParameters.fir.kt b/compiler/testData/diagnostics/tests/shadowing/noNameShadowingForSimpleParameters.fir.kt
new file mode 100644
index 00000000000..bb390470e40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/shadowing/noNameShadowingForSimpleParameters.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_ANONYMOUS_PARAMETER
+
+open class Base {
+    open fun foo(name: String) {}
+}
+
+fun test1(name: String) {
+    class Local : Base() {
+        override fun foo(name: String) {
+        }
+    }
+}
+
+fun test2(param: String) {
+    fun local(param: String) {}
+}
+
+fun test3(param: String) {
+    fun local() {
+        fff { param -> }
+    }
+}
+
+fun fff(x: (y: String) -> Unit) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/afterBinaryExpr.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/afterBinaryExpr.fir.kt
new file mode 100644
index 00000000000..5e3a87c5f02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/afterBinaryExpr.fir.kt
@@ -0,0 +1,14 @@
+package o
+
+class A {
+    <!INAPPLICABLE_INFIX_MODIFIER!>infix fun foo(b: B) = b<!>
+}
+
+class B {
+    fun bar() {}
+}
+
+fun test(a: A, b: B?) {
+    a foo b!!
+    b.bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/alwaysNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/alwaysNull.fir.kt
new file mode 100644
index 00000000000..bfd506229e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/alwaysNull.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+fun foo(): String {
+    var s: String?
+    s = null
+    s?.<!UNRESOLVED_REFERENCE!>length<!>
+    s.<!UNRESOLVED_REFERENCE!>length<!>
+    if (s == null) return s!!
+    var t: String? = "y"
+    if (t == null) t = "x"
+    var x: Int? = null
+    if (x == null) <!UNRESOLVED_REFERENCE!>x += null<!>
+    return t + s
+}
+
+fun String?.gav() {}
+
+fun bar(s: String?) {
+    if (s != null) return
+    s.gav()
+    s as? String
+    s as String?
+    s as String
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/alwaysNullWithJava.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/alwaysNullWithJava.fir.kt
new file mode 100644
index 00000000000..8e2f08fde2b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/alwaysNullWithJava.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// FILE: My.java
+
+public class My {
+    static public My create() { return new My(); }
+    public void foo() {}
+}
+
+// FILE: Test.kt
+
+fun test() {
+    val my = My.create()
+    if (my == null) {
+        my.foo()
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/castchecks/basicOff.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/castchecks/basicOff.fir.kt
new file mode 100644
index 00000000000..f3c2e9eb6a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/castchecks/basicOff.fir.kt
@@ -0,0 +1,36 @@
+// !LANGUAGE: -SafeCastCheckBoundSmartCasts
+
+interface SomeClass {
+    val data: Any?
+}
+
+interface SomeSubClass : SomeClass {
+    val foo: Any?
+}
+
+fun g(a: SomeClass?) {
+    if (a as? SomeSubClass != null) {
+        // 'a' can be cast to SomeSubClass
+        a.hashCode()
+        a.foo
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        (a as SomeSubClass).foo
+    }
+    val b = (a as? SomeSubClass)?.foo
+    if (b != null) {
+        // 'a' can be cast to SomeSubClass
+        a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        a.<!UNRESOLVED_REFERENCE!>foo<!>
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        (a as SomeSubClass).foo
+    }
+    val c = a as? SomeSubClass
+    if (c != null) {
+        // 'a' and 'c' can be cast to SomeSubClass
+        a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        a.<!UNRESOLVED_REFERENCE!>foo<!>
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        c.hashCode()
+        c.foo
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/castchecks/basicOn.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/castchecks/basicOn.fir.kt
new file mode 100644
index 00000000000..0f44fb8b2b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/castchecks/basicOn.fir.kt
@@ -0,0 +1,36 @@
+// !LANGUAGE: +SafeCastCheckBoundSmartCasts
+
+interface SomeClass {
+    val data: Any?
+}
+
+interface SomeSubClass : SomeClass {
+    val foo: Any?
+}
+
+fun g(a: SomeClass?) {
+    if (a as? SomeSubClass != null) {
+        // 'a' can be cast to SomeSubClass
+        a.hashCode()
+        a.foo
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        (a as SomeSubClass).foo
+    }
+    val b = (a as? SomeSubClass)?.foo
+    if (b != null) {
+        // 'a' can be cast to SomeSubClass
+        a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        a.<!UNRESOLVED_REFERENCE!>foo<!>
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        (a as SomeSubClass).foo
+    }
+    val c = a as? SomeSubClass
+    if (c != null) {
+        // 'a' and 'c' can be cast to SomeSubClass
+        a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        a.<!UNRESOLVED_REFERENCE!>foo<!>
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        c.hashCode()
+        c.foo
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/castchecks/impossible.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/castchecks/impossible.fir.kt
new file mode 100644
index 00000000000..0650f50ccb1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/castchecks/impossible.fir.kt
@@ -0,0 +1,25 @@
+// !LANGUAGE: +SafeCastCheckBoundSmartCasts
+// See KT-20752
+
+class Unstable {
+    val first: String? get() = null
+}
+
+class StringList {
+    fun remove(s: String) = s
+}
+
+fun StringList.remove(s: String?) = s ?: ""
+
+fun foo(list: StringList, arg: Unstable) {
+    list.remove(arg.first)
+    if (arg.first as? String != null) {
+        // Should be still resolved to extension, without smart cast or smart cast impossible
+        list.remove(arg.first)
+    }
+    val s = arg.first as? String
+    if (s != null) {
+        // Should be still resolved to extension, without smart cast or smart cast impossible
+        list.remove(arg.first)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/castchecks/insideCall.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/castchecks/insideCall.fir.kt
new file mode 100644
index 00000000000..1ef1dbf1d94
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/castchecks/insideCall.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +SafeCastCheckBoundSmartCasts
+// See KT-19007
+
+// Stub
+fun String.indexOf(arg: String) = this.length - arg.length
+
+// Stub
+fun String.toLowerCase() = this
+
+fun foo(a: Any) {
+    // Should compile in 1.2
+    (a as? String)?.indexOf(a.toLowerCase())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/castchecks/smartCastOfNullableExpressionWithExpectedType.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/castchecks/smartCastOfNullableExpressionWithExpectedType.fir.kt
new file mode 100644
index 00000000000..5ec02b900d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/castchecks/smartCastOfNullableExpressionWithExpectedType.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+class Item(val link: String?)
+
+fun test(item: Item) {
+    if (item.link != null) {
+        val href: String = item.link
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/castchecks/variables.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/castchecks/variables.fir.kt
new file mode 100644
index 00000000000..ed43d37e403
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/castchecks/variables.fir.kt
@@ -0,0 +1,68 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +SafeCastCheckBoundSmartCasts
+interface SomeClass {
+    val data: Any?
+}
+
+interface SomeSubClass : SomeClass {
+    val foo: Any?
+}
+
+object Impl : SomeSubClass {
+    override val data = ""
+    override val foo = 42
+}
+
+fun g(a: SomeClass?) {
+    var b = (a as? SomeSubClass)?.foo
+    b = "Hello"
+    if (b != null) {
+        // 'a' cannot be cast to SomeSubClass!
+        a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        a.<!UNRESOLVED_REFERENCE!>foo<!>
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        (a as SomeSubClass).foo
+    }
+    var c = a as? SomeSubClass
+    c = Impl
+    if (c != null) {
+        // 'a' cannot be cast to SomeSubClass
+        a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        a.<!UNRESOLVED_REFERENCE!>foo<!>
+        (a as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        c.hashCode()
+        c.foo
+    }
+}
+
+fun f(a: SomeClass?) {
+    var aa = a
+
+    if (aa as? SomeSubClass != null) {
+        aa = null
+        // 'aa' cannot be cast to SomeSubClass
+        aa.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+        aa.<!UNRESOLVED_REFERENCE!>foo<!>
+        (aa as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        (aa as SomeSubClass).foo
+    }
+    val b = (aa as? SomeSubClass)?.foo
+    aa = null
+    if (b != null) {
+        // 'aa' cannot be cast to SomeSubClass
+        aa.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+        aa.<!UNRESOLVED_REFERENCE!>foo<!>
+        (aa as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        (aa as SomeSubClass).foo
+    }
+    aa = a
+    val c = aa as? SomeSubClass
+    if (c != null) {
+        // 'c' can be cast to SomeSubClass
+        aa.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+        aa.<!UNRESOLVED_REFERENCE!>foo<!>
+        (aa as? SomeSubClass).<!INAPPLICABLE_CANDIDATE!>foo<!>
+        c.hashCode()
+        c.foo
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/classObjectMember.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/classObjectMember.fir.kt
new file mode 100644
index 00000000000..179c6e4cb9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/classObjectMember.fir.kt
@@ -0,0 +1,22 @@
+open class T {
+    val x : Int? = null
+}
+
+class A {
+    companion object: T() {
+    }
+}
+
+class B {
+    companion object: T() {
+    }
+}
+
+fun test() {
+    if (A.x != null) {
+        useInt(A.x)
+        useInt(B.x)
+    }
+}
+
+fun useInt(i: Int) = i
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/combineWithNoSelectorInfo.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/combineWithNoSelectorInfo.fir.kt
new file mode 100644
index 00000000000..75dad0ee21b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/combineWithNoSelectorInfo.fir.kt
@@ -0,0 +1,13 @@
+package foo
+
+fun dispatch(request: Request) {
+    val url = request.getRequestURI() as String
+
+    if (request.getMethod()?.length != 0) {
+    }
+}
+
+interface Request {
+    fun getRequestURI(): String?
+    fun getMethod(): String?
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/comparisonUnderAnd.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/comparisonUnderAnd.fir.kt
new file mode 100644
index 00000000000..bd37527174d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/comparisonUnderAnd.fir.kt
@@ -0,0 +1,39 @@
+// !WITH_NEW_INFERENCE
+fun foo(x : String?, y : String?) {
+    if (y != null && x == y) {
+        // Both not null
+        x.length
+        y.length
+    }
+    else {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    if (y != null || x == y) {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    else {
+        // y == null but x != y
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    if (y == null && x != y) {
+        // y == null but x != y
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    else {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    if (y == null || x != y) {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    else {
+        // Both not null
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        y.length
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/complexComparison.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/complexComparison.fir.kt
new file mode 100644
index 00000000000..99865dcca58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/complexComparison.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+fun foo(x: String?, y: String?, z: String?, w: String?) {
+    if (x != null && y != null && (x == z || y == z))
+        z.length
+    else
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    if (x != null || y != null || (x != z && y != z))
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    else
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    if (x == null || y == null || (x != z && y != z))
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    else
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    if (x != null && y == x && z == y && w == z)
+        w.length
+    else
+        w.<!INAPPLICABLE_CANDIDATE!>length<!>
+    if ((x != null && y == x) || (z != null && y == z))
+        y.length
+    else
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/complexConditionsWithExcl.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/complexConditionsWithExcl.fir.kt
new file mode 100644
index 00000000000..9ae92c920f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/complexConditionsWithExcl.fir.kt
@@ -0,0 +1,55 @@
+fun foo(x: String?, y: String?, z: String?) {
+    if ((x!!.hashCode() == 0 || y!!.hashCode() == 1) && z!!.hashCode() == 2) {
+        x.length
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+        // condition is true => z!! after and is called
+        z.length
+    }
+    else {
+        x.length
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    // First element is always analyzed
+    x.length
+    var xx = y ?: z
+    if ((xx!!.hashCode() == 0 && y!!.hashCode() == 1) || z!!.hashCode() == 2) {
+        xx.length
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    else {
+        xx.length
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+        // condition is false => z!! after or is called
+        z.length
+    }
+    // First element is always analyzed
+    x.length
+    xx = y ?: z
+    if (xx!!.hashCode() == 0 && y!!.hashCode() == 1 && z!!.hashCode() == 2) {
+        // all three are called
+        xx.length
+        y.length
+        z.length
+    }
+    else {
+        xx.length
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    // First element is always analyzed
+    x.length
+    xx = y ?: z
+    if (xx!!.hashCode() == 0 || y!!.hashCode() == 1 || z!!.hashCode() == 2) {
+        xx.length
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+        z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    else {
+        // all three are called
+        xx.length
+        y.length
+        z.length
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/dataFlowInfoForArguments.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/dataFlowInfoForArguments.fir.kt
new file mode 100644
index 00000000000..ecd89d2641a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/dataFlowInfoForArguments.fir.kt
@@ -0,0 +1,7 @@
+package aaa
+
+fun bar(a: Int, b: Int) {}
+
+fun foo(a: Int?) {
+    bar(a!!, a)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/doubleLambdaArgument.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/doubleLambdaArgument.fir.kt
new file mode 100644
index 00000000000..b889bb2c9b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/doubleLambdaArgument.fir.kt
@@ -0,0 +1,10 @@
+interface Foo
+fun foo(): Foo? = null
+
+val foo: Foo = run {
+    run {
+        val x = foo()
+        if (x == null) throw Exception()
+        x
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvis/basicOff.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvis/basicOff.fir.kt
new file mode 100644
index 00000000000..e8d3d7a6e55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvis/basicOff.fir.kt
@@ -0,0 +1,50 @@
+// !LANGUAGE: -BooleanElvisBoundSmartCasts
+
+interface Order {
+    val expired: Boolean?
+
+    fun notExpired(): Boolean
+
+    fun doSomething()
+}
+
+fun foo(o: Any) {
+    val order = o as? Order
+    if (order?.expired ?: false) {
+        order.<!INAPPLICABLE_CANDIDATE!>doSomething<!>()
+    }
+    else {
+
+    }
+    if (order?.notExpired() ?: false) {
+        order.<!INAPPLICABLE_CANDIDATE!>doSomething<!>()
+    }
+}
+
+fun bar(o: Any) {
+    val order = o as? Order
+    if (order?.expired ?: true) {
+
+    }
+    else {
+        order!!.doSomething()
+    }
+    if (order?.notExpired() ?: true) {
+
+    }
+    else {
+        order!!.doSomething()
+    }
+}
+
+fun baz(o: Boolean?) {
+    if (o ?: false) {
+        o.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    }
+    if (o ?: true) {
+
+    }
+    else {
+        o.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvis/basicOn.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvis/basicOn.fir.kt
new file mode 100644
index 00000000000..b1b04eac84d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvis/basicOn.fir.kt
@@ -0,0 +1,50 @@
+// !LANGUAGE: +BooleanElvisBoundSmartCasts
+
+interface Order {
+    val expired: Boolean?
+
+    fun notExpired(): Boolean
+
+    fun doSomething()
+}
+
+fun foo(o: Any) {
+    val order = o as? Order
+    if (order?.expired ?: false) {
+        order.<!INAPPLICABLE_CANDIDATE!>doSomething<!>()
+    }
+    else {
+
+    }
+    if (order?.notExpired() ?: false) {
+        order.<!INAPPLICABLE_CANDIDATE!>doSomething<!>()
+    }
+}
+
+fun bar(o: Any) {
+    val order = o as? Order
+    if (order?.expired ?: true) {
+
+    }
+    else {
+        order!!.doSomething()
+    }
+    if (order?.notExpired() ?: true) {
+
+    }
+    else {
+        order!!.doSomething()
+    }
+}
+
+fun baz(o: Boolean?) {
+    if (o ?: false) {
+        o.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    }
+    if (o ?: true) {
+
+    }
+    else {
+        o.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvis/impossible.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvis/impossible.fir.kt
new file mode 100644
index 00000000000..cbce948f70f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvis/impossible.fir.kt
@@ -0,0 +1,41 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +BooleanElvisBoundSmartCasts
+// See KT-20752
+
+class Unstable {
+    val first: String? get() = null
+}
+
+class StringList {
+    fun remove(s: String) = s
+}
+
+fun StringList.remove(s: String?) = s ?: ""
+
+fun String.isEmpty() = this == ""
+
+fun foo(list: StringList, arg: Unstable) {
+    list.remove(arg.first)
+    if (arg.first?.isEmpty() ?: false) {
+        // Should be still resolved to extension, without smart cast or smart cast impossible
+        list.remove(arg.first)
+    }
+}
+
+class UnstableBoolean {
+    val first: Boolean? get() = null
+}
+
+class BooleanList {
+    fun remove(b: Boolean) = b
+}
+
+fun BooleanList.remove(b: Boolean?) = b ?: false
+
+fun bar(list: BooleanList, arg: UnstableBoolean) {
+    list.remove(arg.first)
+    if (arg.first ?: false) {
+        // Should be still resolved to extension, without smart cast or smart cast impossible
+        list.remove(arg.first)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvisExclExcl.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvisExclExcl.fir.kt
new file mode 100644
index 00000000000..1b9e8c144a2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvisExclExcl.fir.kt
@@ -0,0 +1,9 @@
+// Based on KT-9100
+fun test(x: Any?, y: Any?): Any {
+    val z = x ?: y!!
+    y.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    // !! / ?. is necessary here, because y!! above may not be executed
+    y?.hashCode()
+    y!!.hashCode()
+    return z
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvisExclExclMerge.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvisExclExclMerge.fir.kt
new file mode 100644
index 00000000000..c23b235a6fa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvisExclExclMerge.fir.kt
@@ -0,0 +1,6 @@
+fun test(x: Any?): Any {
+    val z = x ?: x!!
+    // x is not null in both branches
+    x.hashCode()
+    return z
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvisExclExclPlatform.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvisExclExclPlatform.fir.kt
new file mode 100644
index 00000000000..52d8720b9af
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvisExclExclPlatform.fir.kt
@@ -0,0 +1,27 @@
+// FILE: p/My.java
+
+package p;
+
+import org.jetbrains.annotations.*;
+
+class My {
+    @Nullable static String create() {
+        return "";
+    }
+}
+
+// FILE: test.kt
+
+package p
+
+fun bar(x: String) = x
+
+fun test(x: String?): Any {
+    val y = My.create()
+    val z = x ?: y!!
+    bar(y)
+    // !! / ?. is necessary here, because y!! above may not be executed
+    y?.hashCode()
+    y!!.hashCode()
+    return z
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvisExprNotNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvisExprNotNull.fir.kt
new file mode 100644
index 00000000000..4a86b04553d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvisExprNotNull.fir.kt
@@ -0,0 +1,37 @@
+// !WITH_NEW_INFERENCE
+fun foo(s: Any?): String {
+    val t = when {
+        // To resolve: String U Nothing? = String?
+        s is String -> s
+        else -> null
+    } ?: ""
+    return t
+}
+
+fun bar(s: Any?): String {
+    // To resolve: String U Nothing? = String?
+    val t = (if (s == null) {
+        null
+    }
+    else {
+        val u: Any? = null
+        if (u !is String) return ""
+        u
+    }) ?: "xyz"
+    // Ideally we should have smart cast to String here
+    return t
+}
+
+fun baz(s: String?, r: String?): String {
+    val t = r ?: when {
+        s != null -> s
+        else -> ""
+    }
+    return t
+}
+
+fun withNull(s: String?): String {
+    val t = s ?: null
+    // Error: nullable
+    return t
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvisNothingRHS.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvisNothingRHS.fir.kt
new file mode 100644
index 00000000000..646d4e00d2a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvisNothingRHS.fir.kt
@@ -0,0 +1,11 @@
+class C {
+    fun foo() {}
+}
+
+fun test(a: C?, nn: () -> Nothing?) {
+    a ?: nn()
+    a.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+
+    a ?: return
+    a.foo()
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/elvisRHS.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/elvisRHS.fir.kt
new file mode 100644
index 00000000000..946c75ff9cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/elvisRHS.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+// KT-5335
+
+fun foo(p1: String?, p2: String?) {
+    if (p2 != null) {
+        val v = p1 ?: p2
+        val size = v.length
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_after.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_after.fir.kt
new file mode 100644
index 00000000000..e85df63e2f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_after.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +SoundSmartcastForEnumEntries
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// SKIP_TXT
+
+enum class Message(val text: String?) {
+    HELLO("hello"),
+    WORLD("world"),
+    NOTHING(null)
+}
+
+fun printMessages() {
+    Message.HELLO.text!!
+    Message.HELLO.text.length
+
+    Message.NOTHING.text.length
+
+    Message.NOTHING.text!!
+    Message.NOTHING.text.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_before.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_before.fir.kt
new file mode 100644
index 00000000000..85e9d6542f0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_before.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: -SoundSmartcastForEnumEntries
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// SKIP_TXT
+
+enum class Message(val text: String?) {
+    HELLO("hello"),
+    WORLD("world"),
+    NOTHING(null)
+}
+
+fun printMessages() {
+    Message.HELLO.text!!
+    Message.HELLO.text.length
+
+    Message.NOTHING.text.length
+
+    Message.NOTHING.text!!
+    Message.NOTHING.text.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/equals.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/equals.fir.kt
new file mode 100644
index 00000000000..1de64d0d3b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/equals.fir.kt
@@ -0,0 +1,25 @@
+fun foo(x: String?) = x
+
+class Test
+
+class TestWithEquals {
+    override fun equals(other: Any?) = super.equals(other)
+}
+
+fun bar(i: Test?) {
+    if (i == null) <!INAPPLICABLE_CANDIDATE!>foo<!>(i)
+}
+
+fun bar(i: TestWithEquals?) {
+    if (i == null) <!INAPPLICABLE_CANDIDATE!>foo<!>(i)
+    if (null == i) <!INAPPLICABLE_CANDIDATE!>foo<!>(i)
+    when (i) {
+        null -> <!INAPPLICABLE_CANDIDATE!>foo<!>(i)
+    }
+}
+
+fun gav(i: TestWithEquals?, j: TestWithEquals?) {
+    if (j == null) {
+        if (i == j) <!INAPPLICABLE_CANDIDATE!>foo<!>(i)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/exclUnderAnd.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/exclUnderAnd.fir.kt
new file mode 100644
index 00000000000..8b32be493ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/exclUnderAnd.fir.kt
@@ -0,0 +1,13 @@
+class D(val a: String, val b: Boolean)
+
+fun foo(p: Boolean, v: D?): String {
+    if (p && v!!.b) v.a
+    else v.<!INAPPLICABLE_CANDIDATE!>a<!>
+    if (p && v!! == D("?", false)) v.a
+    else v.<!INAPPLICABLE_CANDIDATE!>a<!>
+    if (p || v!!.b) v.<!INAPPLICABLE_CANDIDATE!>a<!>
+    else v.a
+    if (p || v!! == D("?", false)) v.<!INAPPLICABLE_CANDIDATE!>a<!>
+    else v.a
+    return ""
+} 
diff --git a/compiler/testData/diagnostics/tests/smartCasts/explicitDefaultGetter.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/explicitDefaultGetter.fir.kt
new file mode 100644
index 00000000000..9b688c538ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/explicitDefaultGetter.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+class ExplicitAccessorForAnnotation {
+    val tt: String? = "good"
+        get
+
+    fun foo(): String {
+        if (tt is String) {
+            return tt
+        }
+        return ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/extensionSafeCall.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/extensionSafeCall.fir.kt
new file mode 100644
index 00000000000..36e4758349e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/extensionSafeCall.fir.kt
@@ -0,0 +1,13 @@
+class Your
+
+fun Your.foo() = Any()
+
+fun <T> T?.let(f: (T) -> Unit) {
+    if (this != null) f(this)
+}
+
+fun test(your: Your?) {
+    (your?.foo() as? Any)?.let {}
+    // strange smart cast to 'Your' at this point
+    your.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/fakeSmartCastOnEquality.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/fakeSmartCastOnEquality.fir.kt
new file mode 100644
index 00000000000..63e29c46afd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/fakeSmartCastOnEquality.fir.kt
@@ -0,0 +1,95 @@
+abstract class Base {
+    override fun equals(other: Any?) = other is Base
+}
+
+class Derived1 : Base() {
+    fun foo() {}
+}
+
+class Derived2 : Base()
+
+fun check(x1: Derived1, x: Base) {
+    if (x1 == x) {
+        // Smart cast here will provoke CCA
+        x.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+    if (x1 === x) {
+        // OK
+        x.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+    if (x1 !== x) {} else {
+        // OK
+        x.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+}
+
+class FinalClass { // <-- 'equals' on instances of this class is useful for smart casts
+    fun use() {}
+
+    fun equals(x: Int): Boolean = x > 42
+}
+
+fun foo(x: FinalClass?, y: Any) {
+    if (x == y) {
+        // OK
+        x.hashCode()
+        // OK
+        y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+    when (x) {
+        // OK (equals from FinalClass)
+        y -> y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+    when (y) {
+        // ERROR (equals from Any)
+        x -> y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+}
+
+open class OpenClass {
+    override fun equals(other: Any?) = other is OpenClass
+}
+
+interface Dummy // should not influence anything
+
+class FinalClass2 : Dummy, OpenClass() { // but here not
+    fun use() {}
+}
+
+fun bar(x: FinalClass2?, y: Any) {
+    if (x == y) {
+        // OK
+        x.hashCode()
+        // ERROR
+        y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+}
+
+open class OpenClass2 // and here too
+
+fun bar(x: OpenClass2?, y: Any) {
+    if (x == y) {
+        // OK
+        x.hashCode()
+        // ERROR
+        y.<!UNRESOLVED_REFERENCE!>use<!>()
+    }
+}
+
+sealed class Sealed {
+    override fun equals(other: Any?) = other is Sealed
+
+    class Sealed1 : Sealed() {
+        fun gav() {}
+    }
+
+    object Sealed2 : Sealed()
+
+    fun check(arg: Sealed1) {
+        if (arg == this) {
+            // Smart cast here will provoke CCA
+            this.<!UNRESOLVED_REFERENCE!>gav<!>()
+            <!UNRESOLVED_REFERENCE!>gav<!>()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/falseReceiverSmartCast.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/falseReceiverSmartCast.fir.kt
new file mode 100644
index 00000000000..2f6711d7a70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/falseReceiverSmartCast.fir.kt
@@ -0,0 +1,15 @@
+open class SuperFoo {
+    public fun bar(): String {
+        if (this is Foo) {
+            superFoo()
+            return baz()
+        }
+        return baz()
+    }
+
+    public fun baz() = "OK"
+}
+
+class Foo : SuperFoo() {
+    public fun superFoo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/falseUnnecessaryCall.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/falseUnnecessaryCall.fir.kt
new file mode 100644
index 00000000000..90df45ae42b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/falseUnnecessaryCall.fir.kt
@@ -0,0 +1,11 @@
+// See KT-10276
+
+class Bar() {
+    var test: String? = null
+    fun foo() {
+        if (test != null) {
+            // No warning: test is a mutable property
+            test?.hashCode()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/fieldExclExcl.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/fieldExclExcl.fir.kt
new file mode 100644
index 00000000000..af571c2a743
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/fieldExclExcl.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNNECESSARY_NOT_NULL_ASSERTION
+// See KT-9126: Variable change does not affect data flow info for its fields
+
+class My(val x: Int?)
+
+fun foo() {
+    var y: My? = My(42)
+    if (y!!.x != null) {
+        y = My(null)
+        y!!.x.hashCode()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/fieldInGetter.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/fieldInGetter.fir.kt
new file mode 100644
index 00000000000..98cc0be686a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/fieldInGetter.fir.kt
@@ -0,0 +1,5 @@
+val x: Int? = 0
+    get() {
+        if (field != null) return field.hashCode()
+        return null
+    }
diff --git a/compiler/testData/diagnostics/tests/smartCasts/fieldPlus.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/fieldPlus.fir.kt
new file mode 100644
index 00000000000..ee986476817
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/fieldPlus.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNNECESSARY_NOT_NULL_ASSERTION
+// Advancement of KT-9126
+
+class My(val x: Int?) {
+    operator fun plus(y: My) = if (this.x != null) this else y
+}
+
+fun foo() {
+    var y: My? = My(42)
+    if (y!!.x != null) {
+        y = My(null)
+        (y + My(0)).x.hashCode()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/genericIntersection.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/genericIntersection.fir.kt
new file mode 100644
index 00000000000..9dae20755e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/genericIntersection.fir.kt
@@ -0,0 +1,7 @@
+// See also KT-7801
+class A
+
+fun <T> test(v: T): T {
+    val a: T = if (v !is A) v else v
+    return a
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/genericSet.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/genericSet.fir.kt
new file mode 100644
index 00000000000..349daeb25a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/genericSet.fir.kt
@@ -0,0 +1,7 @@
+class Wrapper<T>(var x: T)
+
+inline fun <reified T> change(w: Wrapper<T>, x: Any?) {
+    if (x is T) {
+        w.x = x
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/ifCascadeExprNotNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/ifCascadeExprNotNull.fir.kt
new file mode 100644
index 00000000000..563e1c1bf03
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/ifCascadeExprNotNull.fir.kt
@@ -0,0 +1,14 @@
+fun baz(s: String?): String {
+    val t = if (s == null) {
+        ""
+    }
+    else if (s == "") {
+        val u: String? = null
+        if (u == null) return ""
+        u
+    }
+    else {
+        s
+    }
+    return t
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/ifExprInConditionNonNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/ifExprInConditionNonNull.fir.kt
new file mode 100644
index 00000000000..10a55ca5ab2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/ifExprInConditionNonNull.fir.kt
@@ -0,0 +1,11 @@
+fun baz(s: String?, b: Boolean?): String {
+    val t = if (if (b == null) return "" else b) {
+        if (s == null) return ""
+        s
+    }
+    else {
+        if (s != null) return s
+        ""
+    }
+    return t
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/ifExprInWhenSubjectNonNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/ifExprInWhenSubjectNonNull.fir.kt
new file mode 100644
index 00000000000..946abe223a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/ifExprInWhenSubjectNonNull.fir.kt
@@ -0,0 +1,11 @@
+fun baz(s: String?, u: String?): String {
+    val t = when(if (u == null) return "" else u) {
+        "abc" -> u
+        "" -> {
+            if (s == null) return ""
+            s
+        }
+        else -> u
+    }
+    return t
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/ifExprNonNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/ifExprNonNull.fir.kt
new file mode 100644
index 00000000000..ddc82cc4d68
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/ifExprNonNull.fir.kt
@@ -0,0 +1,19 @@
+fun baz(s: String?): String {
+    // If String type is given explicitly, problem disappears
+    val t = if (s == null) {
+        ""
+    }
+    else {
+        val u: String? = null
+        if (u == null) return ""
+        // !! is detected as unnecessary here
+        u
+    }
+    return t
+}
+
+fun foo(s: String?): String {
+    if (s == null) return ""
+    val t = if (s == "abc") s else "xyz"
+    return t
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/ifWhenExprNonNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/ifWhenExprNonNull.fir.kt
new file mode 100644
index 00000000000..bef5189c355
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/ifWhenExprNonNull.fir.kt
@@ -0,0 +1,13 @@
+fun baz(s: String?): String {
+    val t = if (s == null) {
+        ""
+    }
+    else {
+        val u: String? = null
+        when (u) {
+            null -> ""
+            else -> u
+        }
+    }
+    return t
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/implicitReceiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/implicitReceiver.fir.kt
new file mode 100644
index 00000000000..62d0141a968
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/implicitReceiver.fir.kt
@@ -0,0 +1,29 @@
+open class A {
+    class B : A() {
+        val a = "FAIL"
+    }
+
+    class C : A() {
+        val a = "FATAL"
+    }
+
+    fun foo(): String {
+        if (this is B) return a
+        else if (this is C) return a
+        return "OK"
+    }
+}
+
+fun A?.bar() {
+    if (this != null) foo()
+}
+
+fun A.gav() = if (this is A.B) a else ""
+
+class C {
+    fun A?.complex(): String {
+        if (this is A.B) return a
+        else if (this != null) return foo()
+        else return ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/implicitToGrandSon.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/implicitToGrandSon.fir.kt
new file mode 100644
index 00000000000..aa90fc31447
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/implicitToGrandSon.fir.kt
@@ -0,0 +1,11 @@
+open class A {
+    open fun foo() = "FAIL"
+
+    fun bar() = if (this is C) foo() else "FAIL"
+}
+
+open class B : A()
+
+open class C : B() {
+    override fun foo() = "OK"
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/incDecToNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/incDecToNull.fir.kt
new file mode 100644
index 00000000000..aea96ca9533
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/incDecToNull.fir.kt
@@ -0,0 +1,10 @@
+class IncDec {
+    operator fun inc(): Unit {}
+}
+
+fun foo(): IncDec {
+    var x = IncDec()
+    x = x++
+    x++
+    return x
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/dependentOnPrevArg.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/dependentOnPrevArg.fir.kt
new file mode 100644
index 00000000000..8df11c2d476
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/dependentOnPrevArg.fir.kt
@@ -0,0 +1,7 @@
+package a
+
+fun <T> foo(u: T, v: T): T = u
+
+fun test(s: String?) {
+    val r: String = foo(s!!, s)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/intersectionTypes.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/intersectionTypes.fir.kt
new file mode 100644
index 00000000000..5bfb285c232
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/intersectionTypes.fir.kt
@@ -0,0 +1,61 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+package a
+
+fun <T> id(t: T): T = t
+
+fun <T> two(u: T, v: T): T = u
+
+fun <T> three(a: T, b: T, c: T): T = c
+
+interface A
+interface B: A
+interface C: A
+
+fun test(a: A, b: B, c: C) {
+    if (a is B && a is C) {
+        val d: C = id(a)
+        val e: Any = id(a)
+        val f = id(a)
+        checkSubtype<A>(f)
+        val g = two(a, b)
+        checkSubtype<B>(g)
+        checkSubtype<A>(g)
+
+        // smart cast isn't needed, but is reported due to KT-4294
+        val h: Any = two(a, b)
+
+        val k = three(a, b, c)
+        checkSubtype<A>(k)
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><B>(k)
+        val l: Int = three(a, b, c)
+        
+        use(d, e, f, g, h, k, l)
+    }
+}
+
+fun <T> foo(t: T, l: MutableList<T>): T = t
+
+fun testErrorMessages(a: A, ml: MutableList<String>) {
+    if (a is B && a is C) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(a, ml)
+    }
+
+    if(a is C) {
+        <!INAPPLICABLE_CANDIDATE!>foo<!>(a, ml)
+    }
+}
+
+fun rr(s: String?) {
+    if (s != null) {
+        val l = arrayListOf("", s)
+        checkSubtype<MutableList<String>>(l)
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><MutableList<String?>>(l)
+    }
+}
+
+//from library
+fun <T> arrayListOf(vararg values: T): MutableList<T> = throw Exception()
+
+fun use(vararg a: Any) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt1275.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt1275.fir.kt
new file mode 100644
index 00000000000..3e8b55e329b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt1275.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+fun foo(s : String?, b : Boolean) {
+    if (s == null) return
+
+    val s1 = if (b) "" else s
+    s1 checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    val s2 = s
+    s2 checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt1355.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt1355.fir.kt
new file mode 100644
index 00000000000..4e0ea846b5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt1355.fir.kt
@@ -0,0 +1,40 @@
+//KT-1355 Type inference fails with smartcast and generic function
+//tests for Map.set
+package a
+
+import java.util.HashMap
+
+fun foo(map: MutableMap<Int, String>, value: String?) {
+    if (value != null) {
+        map.put(1, value) //ok
+        map.set(1, value) //type inference failed
+        map[1] = value    //type inference failed
+    }
+}
+
+//---------------------------
+
+public data class Tag(public var tagName: String) {
+    public val attributes: MutableMap<String, String> = HashMap<String, String>()
+    public val contents: MutableList<Tag> = arrayListOf()
+
+    public var id: String?
+        get() = attributes["id"]
+        set(value) {
+            if(value == null) {
+                attributes.remove("id")
+            }
+            else {
+                attributes["id"] = value!!
+                attributes["id"] = value
+            }
+        }
+}
+
+
+//from library
+operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) = this.put(key, value)
+
+fun <T> arrayListOf(vararg values: T): MutableList<T> = throw Exception()
+
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt25432.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt25432.fir.kt
new file mode 100644
index 00000000000..0349104af9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt25432.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// ISSUE: KT-25432
+
+class Data<T>(val s: T)
+
+fun test(d: Data<out Any>) {
+    if (d.s is String) {
+        d.s.length
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt2746.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt2746.fir.kt
new file mode 100644
index 00000000000..d7a7381c7d0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt2746.fir.kt
@@ -0,0 +1,18 @@
+//KT-2746 Do.smartcasts in inference
+
+class C<T>(t :T)
+
+fun test1(a: Any) {
+    if (a is String) {
+        val c: C<String> = C(a)
+    }
+}
+
+
+fun <T> f(t :T): C<T> = C(t)
+
+fun test2(a: Any) {
+    if (a is String) {
+        val c1: C<String> = f(a)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt2851.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt2851.fir.kt
new file mode 100644
index 00000000000..404e80ba754
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt2851.fir.kt
@@ -0,0 +1,20 @@
+//KT-2851 Type inference failed passing in not-null after smart-cast value in Pair
+package a
+
+fun main() {
+    val value: String? = ""
+    if (value != null) {
+        foo(Pair("val", value))
+        foo(Pair("val", value!!))
+        foo(Pair<String, String>("val", value))
+    }
+}
+
+fun foo(map: Pair<String, String>) {}
+
+
+//from library
+public class Pair<out A, out B> (
+        public val first: A,
+        public val second: B
+)
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt29767.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt29767.fir.kt
new file mode 100644
index 00000000000..e2b74b41c29
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt29767.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+// ISSUE: KT-29767
+
+fun test(a: MutableList<out Int?>?) {
+    if (a != null) {
+        val b = a[0] // no SMARTCAST diagnostic
+        if (b != null) {
+            b.inc()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt4009.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt4009.fir.kt
new file mode 100644
index 00000000000..a293d1cb1e1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt4009.fir.kt
@@ -0,0 +1,22 @@
+interface PsiElement {
+    fun getText(): String
+    fun getParent(): PsiElement
+}
+
+interface JetExpression : PsiElement
+
+fun foo1(e: PsiElement) {
+    var current: PsiElement? = e
+    var first = true
+    while (current != null) {
+        if (current is JetExpression && first) {
+            // Smartcast is possible here
+            println(current.getText())
+        }
+
+        current = current.getParent()
+    }
+}
+
+//from library
+fun println(any: Any?): Nothing = throw Exception("$any")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt4403.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt4403.fir.kt
new file mode 100644
index 00000000000..89c463b18ae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt4403.fir.kt
@@ -0,0 +1,11 @@
+//KT-4403 Wrong "type mismatch" on smart cast with inference
+
+interface A
+interface B : A
+
+fun <T> T.f(): T = this
+
+fun test(a: A) {
+    if (a !is B) return
+    val c = a.f() // type mismatch
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt4415.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt4415.fir.kt
new file mode 100644
index 00000000000..8ef9bc2f460
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt4415.fir.kt
@@ -0,0 +1,17 @@
+//KT-4415 Class Auto-Cast Bug
+
+interface SelfJson
+
+object A {
+    fun find(clz:Class<*>){  }
+
+    fun toJson2(obj:Any){
+        if(obj is SelfJson){
+            // A.find( (obj as SelfJson).javaClass)  // OK
+            A.find( obj.javaClass )   // ERROR:  Type mismatch: inferred type is kotlin.Any but SelfJson was expected
+        }
+    }
+}
+
+//from library
+val <T> T.javaClass : Class<T> get() = throw Exception()
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.fir.kt
new file mode 100644
index 00000000000..84346be5de6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline fun<T> foo(block: () -> T):T = block()
+
+fun baz() {
+    val x: String = foo {
+        val task: String? = null
+        if (task == null) {
+            return
+        } else task
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.fir.kt
new file mode 100644
index 00000000000..c298ad299c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.fir.kt
@@ -0,0 +1,13 @@
+interface A
+interface B
+
+class Test {
+    fun test(a: A?, b: B, list: MutableList<Pair<A, B>>) {
+        if (a != null) {
+            list.add(a to b)
+        }
+    }
+}
+
+class Pair<out A, out B>(val first: A, val second: B)
+infix fun <A, B> A.to(that: B) = Pair(this, that)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/conflictTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/conflictTypeParameters.fir.kt
new file mode 100644
index 00000000000..a833621f989
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/conflictTypeParameters.fir.kt
@@ -0,0 +1,13 @@
+interface A {
+    fun <T, E> foo(): E
+}
+
+interface B {
+    fun <Q, W> foo(): Q
+}
+
+fun test(c: Any) {
+    if (c is B && c is A) {
+        c.<!AMBIGUITY!>foo<!><String, Int>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/conflictingReturnType.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/conflictingReturnType.fir.kt
new file mode 100644
index 00000000000..3c5dc3b8e9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/conflictingReturnType.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+interface A {
+    fun foo(): CharSequence
+}
+
+interface B {
+    fun foo(): String?
+}
+
+fun test(c: Any) {
+    if (c is B && c is A) {
+        c.<!AMBIGUITY!>foo<!>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/flexibleTypes.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/flexibleTypes.fir.kt
new file mode 100644
index 00000000000..d44c1402af0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/flexibleTypes.fir.kt
@@ -0,0 +1,53 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+// FILE: A.java
+public interface A {
+    String foo();
+}
+
+// FILE: main.kt
+
+interface B {
+    fun foo(): String?
+}
+
+interface C {
+    fun foo(): String
+}
+
+fun foo(x: Any?) {
+    if (x is A && x is B) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    }
+
+    if (x is B && x is A) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    }
+
+    if (x is A && x is C) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    }
+
+    if (x is C && x is A) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    }
+
+    if (x is A && x is B && x is C) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    }
+
+    if (x is B && x is A && x is C) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    }
+
+    if (x is B && x is C && x is A) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String?>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/moreSpecificSetter.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/moreSpecificSetter.fir.kt
new file mode 100644
index 00000000000..dedf3dd462d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/moreSpecificSetter.fir.kt
@@ -0,0 +1,15 @@
+open class A {
+    open var value: Int = 4
+        protected set
+}
+
+class MutableA : A() {
+    override var value: Int = 4
+        public set
+}
+
+fun test(myA: A) {
+    if (myA is MutableA) {
+        myA.value = 5
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/moreSpecificVisibility.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/moreSpecificVisibility.fir.kt
new file mode 100644
index 00000000000..7fba012cc4b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/moreSpecificVisibility.fir.kt
@@ -0,0 +1,16 @@
+abstract class A {
+    abstract protected fun foo(): String
+    abstract protected val bar: String
+}
+
+interface B {
+    fun foo(): String
+    val bar: String
+}
+
+fun test(x: A) {
+    if (x is B) {
+        x.foo()
+        x.bar
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/mostSpecific.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/mostSpecific.fir.kt
new file mode 100644
index 00000000000..3563574ea66
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/mostSpecific.fir.kt
@@ -0,0 +1,19 @@
+// !CHECK_TYPE
+
+interface Common {
+    fun foo(): CharSequence?
+}
+
+interface A : Common {
+    override fun foo(): CharSequence
+}
+
+interface B : Common {
+    override fun foo(): String
+}
+
+fun test(c: Common) {
+    if (c is B && c is A) {
+        c.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/mostSpecificIrrelevant.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/mostSpecificIrrelevant.fir.kt
new file mode 100644
index 00000000000..3b35a6c40c9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/mostSpecificIrrelevant.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+interface A {
+    fun foo(): CharSequence?
+}
+
+interface B {
+    fun foo(): String
+}
+
+fun test(c: Any) {
+    if (c is B && c is A) {
+        c.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/properties.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/properties.fir.kt
new file mode 100644
index 00000000000..30a57852fbc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/properties.fir.kt
@@ -0,0 +1,21 @@
+// !CHECK_TYPE
+
+interface A {
+    val foo: Any?
+}
+
+interface C: A {
+    override val foo: String?
+}
+interface B: A {
+    override var foo: String
+}
+
+fun test(a: A) {
+    if (a is B && a is C) {
+        a.<!AMBIGUITY!>foo<!> = ""
+        a.<!AMBIGUITY!>foo<!> = null
+
+        a.<!AMBIGUITY!>foo<!>.<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/propertiesConflict.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/propertiesConflict.fir.kt
new file mode 100644
index 00000000000..d899c00e3c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/propertiesConflict.fir.kt
@@ -0,0 +1,20 @@
+// !CHECK_TYPE
+
+interface A {
+    val foo: Any?
+}
+
+interface C: A {
+    override val foo: String
+}
+interface B: A {
+    override var foo: String?
+}
+
+fun test(a: A) {
+    if (a is B && a is C) {
+        a.<!AMBIGUITY!>foo<!> = ""
+        a.<!AMBIGUITY!>foo<!> = null
+        a.<!AMBIGUITY!>foo<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/refineReturnType.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/refineReturnType.fir.kt
new file mode 100644
index 00000000000..3d28cf54515
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/refineReturnType.fir.kt
@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+interface A {
+    fun foo(): CharSequence?
+}
+
+interface B : A {
+    override fun foo(): String
+}
+
+fun test(a: A) {
+    if (a is B) {
+        a.foo()
+        a.foo().checkType { _<String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/simple.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/simple.fir.kt
new file mode 100644
index 00000000000..27b0b8f0f0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/simple.fir.kt
@@ -0,0 +1,12 @@
+interface A {
+    fun foo()
+}
+
+interface C: A
+interface B: A
+
+fun test(c: C) {
+    if (c is B) {
+        c.foo() // OVERLOAD_RESOLUTION_AMBIGUITY: B.foo() and C.foo()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/unstableSmartCast.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/unstableSmartCast.fir.kt
new file mode 100644
index 00000000000..c2a22a07fa2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/unstableSmartCast.fir.kt
@@ -0,0 +1,38 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+interface A {
+    fun foo(): CharSequence?
+    fun baz(x: Any) {}
+}
+
+interface B {
+    fun foo(): String
+    fun baz(x: Int): String =""
+    fun baz(x: Int, y: Int) {}
+
+    fun foobar(): CharSequence?
+}
+
+interface C {
+    fun foo(): String
+    fun baz(x: Int): String =""
+    fun baz(x: Int, y: Int) {}
+
+    fun foobar(): String
+}
+
+var x: A = null!!
+
+fun test() {
+    x.foo().checkType { _<CharSequence?>() }
+
+    if (x is B && x is C) {
+        x.<!AMBIGUITY!>foo<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><CharSequence?>() }
+        x.baz("")
+        x.<!AMBIGUITY!>baz<!>(1).<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Unit>() }
+        x.<!AMBIGUITY!>baz<!>(1, 2)
+
+        x.<!AMBIGUITY!>foobar<!>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/validTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/validTypeParameters.fir.kt
new file mode 100644
index 00000000000..300e51b8910
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/validTypeParameters.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+interface A {
+    fun <T, E> foo(): E
+}
+
+interface B {
+    fun <Q, W> foo(): W
+}
+
+fun test(c: Any) {
+    if (c is B && c is A) {
+        c.<!AMBIGUITY!>foo<!><String, Int>().<!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/validTypeParametersNoSmartCast.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/validTypeParametersNoSmartCast.fir.kt
new file mode 100644
index 00000000000..d17eaa3f9a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/intersectionScope/validTypeParametersNoSmartCast.fir.kt
@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+
+interface A {
+    fun <T, E> foo(): E
+}
+
+interface B : A {
+    override fun <Q, W> foo(): W
+}
+
+fun test(a: A) {
+    if (a is B) {
+        a.foo<String, Int>().checkType { _<Int>() }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt10232.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt10232.fir.kt
new file mode 100644
index 00000000000..00840f11164
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt10232.fir.kt
@@ -0,0 +1,15 @@
+//  Type inference failed after smart cast
+
+interface A<T>
+interface B<T> : A<T>
+
+fun <T> foo(b: A<T>) = b
+
+fun <T> test(a: A<T>) {
+    if (a is Any) {
+        // Error:(9, 9) Kotlin: Type inference failed: fun <T> foo(b: A<T>): kotlin.Unit
+        // cannot be applied to (A<T>)
+        foo(a)
+    }   
+    foo(a) // ok
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt10444.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt10444.fir.kt
new file mode 100644
index 00000000000..97af8b97801
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt10444.fir.kt
@@ -0,0 +1,35 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// KT-10444 Do not ignore smart (unchecked) casts to the same classifier
+
+class Qwe<T : Any>(val a: T?) {
+    fun test1(obj: Any) {
+        obj as Qwe<T>
+        check(obj.a)
+    }
+
+    fun test1(obj: Qwe<*>) {
+        obj as Qwe<T>
+        check(obj.a)
+    }
+
+    fun check(a: T?) {
+    }
+}
+
+open class Foo
+open class Bar<T: Foo>(open val a: T?, open val b: T?) {
+    @Suppress("UNCHECKED_CAST")
+    fun compare(obj: Any) {
+        if (obj !is Bar<*>) {
+            throw IllegalArgumentException()
+        }
+        if (System.currentTimeMillis() > 100) {
+            val b = (obj as Bar<T>).b
+            if (b == null) throw IllegalArgumentException()
+            check(obj.a, b)
+        }
+    }
+    fun check(a: T?, b: T) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt10483.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt10483.fir.kt
new file mode 100644
index 00000000000..370f2ca6299
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt10483.fir.kt
@@ -0,0 +1,17 @@
+interface A
+class B : A {
+    operator fun invoke() = this
+}
+
+class C : A
+
+operator fun C.invoke(): B = B()
+
+fun foo(arg: A): B? {
+    if (arg is B) return arg()
+
+    if (arg is C) return arg()
+
+    return null
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt1461.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt1461.fir.kt
new file mode 100644
index 00000000000..bda384bf859
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt1461.fir.kt
@@ -0,0 +1,18 @@
+//KT-1461 Front-end complains on overload resolution when superclass property is accessed from string template and implicit type cast is performed
+package f
+
+open class Super(val property : String) {}
+
+class Sub(str : String) : Super(str) {}
+
+fun foo(sup : Super, sub : Sub) {
+    if (sup is Sub) {
+        println("${sup.property}")
+        println(sup.property)
+    }
+    println("${sub.property}")
+    println(sub.property)
+}
+
+//from library
+fun println(message : Any?) { throw Exception() }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt2422.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt2422.fir.kt
new file mode 100644
index 00000000000..09602746baa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt2422.fir.kt
@@ -0,0 +1,23 @@
+package bar
+
+class Test {
+    val foo: Int? = null
+    fun foo(o: Test) = foo == null && o.foo == null // ERROR warning: o.test == null is always true
+
+    fun bar(a: Test, b: Test) {
+        if (a.foo != null) {
+            useInt(b.foo)
+        }
+        if (a.foo != null) {
+            useInt(foo)
+        }
+        if (this.foo != null) {
+            useInt(foo)
+        }
+        if (foo != null) {
+            useInt(this.foo)
+        }
+    }
+
+    fun useInt(i: Int) = i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt27221.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt27221.fir.kt
new file mode 100644
index 00000000000..5ff5d106d13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt27221.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// SKIP_TXT
+
+sealed class A
+sealed class B : A()
+sealed class C : B()
+object BB : B()
+object CC : C()
+
+fun foo(a: A) {
+    if (a is B) {
+        if (a is C) {
+            val t = when (a) {
+                is CC -> "CC"
+            }
+        }
+    }
+}
+
+fun foo2(a: A) {
+    if (a is C) {
+        if (a is B) {
+            val t = when (a) {
+                is CC -> "CC"
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt27221_2.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt27221_2.fir.kt
new file mode 100644
index 00000000000..91d54894917
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt27221_2.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// SKIP_TXT
+
+sealed class A
+sealed class B : A()
+sealed class C : B()
+sealed class D : C()
+object BB : B()
+object CC : C()
+object DD : D()
+
+fun foo1(a: A) {
+    if (a is B) {
+        if (a is D) {
+            if (a is C) {
+                val t =
+                    when (a) {
+                        is DD -> "DD"
+                    }
+            }
+        }
+    }
+}
+
+fun foo2(a: A) {
+    if (a is B) {
+        if (a is D) {
+            if (a is C) {
+                val t =
+                    when (a) {
+                        is DD -> "DD"
+                    }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt27221_irrelevantClasses.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt27221_irrelevantClasses.fir.kt
new file mode 100644
index 00000000000..337c36e7ba1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt27221_irrelevantClasses.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// SKIP_TXT
+
+sealed class A
+sealed class B : A()
+sealed class C : A()
+object BB : B()
+object CC : C()
+
+fun foo(a: A) {
+    if (a is B) {
+        if (a is C) {
+            val t = when (a) {
+                is CC -> "CC"
+            }
+        }
+    }
+}
+
+fun foo2(a: A) {
+    if (a is C) {
+        if (a is B) {
+            val t = when (a) {
+                    is CC -> "CC"
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt2865.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt2865.fir.kt
new file mode 100644
index 00000000000..aa67f2a7f65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt2865.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+operator fun <K, V> MutableMap<K, V>.set(k: K, v: V) {}
+
+fun foo(a: MutableMap<String, String>, x: String?) {
+    a[x!!] = x
+    a[x] = x!!
+}
+
+fun foo1(a: MutableMap<String, String>, x: String?) {
+    a[x] = x!!
+    a[x!!] = x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt30826.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt30826.fir.kt
new file mode 100644
index 00000000000..e61914a5daf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt30826.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// Issue: KT-30826
+
+interface I1
+interface I2 {
+    fun foo() {}
+}
+
+class A : I1, I2
+
+fun foo(x: I1?) {
+    var y = x
+    y as I2
+    val bar = {
+        y.foo() // NPE in NI, smartcast impossible in OI
+    }
+    y = null
+    bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt30927.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt30927.fir.kt
new file mode 100644
index 00000000000..9ae3e219581
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt30927.fir.kt
@@ -0,0 +1,51 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+fun case_0() {
+    val z: Any? = 10
+    val y = z.run {
+        this as Int
+        this // error in NI: required Int, found Any?; just inferred to Any? in OI
+    }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
+
+fun case_1(z: Any?) {
+    val y = z.run {
+        when (this) {
+            is String -> return@run this // type mismatch in the new inference (required String, found Any?)
+            is Float -> ""
+            else -> return@run ""
+        }
+    }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><kotlin.String>() }
+    // y is inferred to Any?
+}
+
+fun case_2(z: Any?) {
+    val y = z.run {
+        when (this) {
+            is String -> this
+            is Float -> ""
+            else -> return@run ""
+        }
+    }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><kotlin.String>() }
+    // y is inferred to String
+}
+
+fun case_3(z: Any?) {
+    val y = z.let {
+        when (it) {
+            is String -> return@let it
+            is Float -> ""
+            else -> return@let ""
+        }
+    }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><Any?>() }
+    y checkType { <!UNRESOLVED_REFERENCE!>_<!><kotlin.String>() }
+    // y is inferred to String
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt3224.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt3224.fir.kt
new file mode 100644
index 00000000000..1bd312dc7b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt3224.fir.kt
@@ -0,0 +1,8 @@
+// Works already in M11
+
+fun test(c : Class<*>) {
+    val sc = c as Class<String>
+    // No ambiguous overload
+    c.getAnnotations();
+    sc.getAnnotations();
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt3244.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt3244.fir.kt
new file mode 100644
index 00000000000..a8d568a972e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt3244.fir.kt
@@ -0,0 +1,12 @@
+// Should work already in M11
+
+open class A(val s : String)
+class B(s : String) : A(s)
+
+fun test(a : A): String? {
+    if (a is B) {
+        // Earlier (14.01.2013) reported overload ambiguity over s
+        return a.s 
+    }
+    return null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt3572.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt3572.fir.kt
new file mode 100644
index 00000000000..fc792d1ca81
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt3572.fir.kt
@@ -0,0 +1,17 @@
+interface Printer {
+    fun print()
+}
+
+class OKPrinter : Printer {
+    override fun print() {  }
+}
+
+class MyClass(var printer: Printer)
+
+
+fun main(m: MyClass) {
+    if (m.printer is OKPrinter) {
+        // We do not need smart cast here, so we should not get SMARTCAST_IMPOSSIBLE
+        m.printer.print()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt3711.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt3711.fir.kt
new file mode 100644
index 00000000000..947722ee64c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt3711.fir.kt
@@ -0,0 +1,9 @@
+data class StringPair(val first: String, val second: String)
+
+infix fun String.to(second: String) = StringPair(this, second)
+
+fun f(a: String?) {
+    if (a != null) {
+        val b: StringPair = a to a
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt3899.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt3899.fir.kt
new file mode 100644
index 00000000000..23fc330973c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt3899.fir.kt
@@ -0,0 +1,13 @@
+data class StringPair(val first: String, val second: String)
+
+infix fun String.to(second: String) = StringPair(this, second)
+
+fun hashMapOf(pair: StringPair): MutableMap<String, String> {
+}
+
+fun F() : MutableMap<String, String> {
+    val value: String? = "xyz"
+    if (value == null) throw Error()
+    // Smart cast should be here
+    return hashMapOf("sss" to value)  
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt3993.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt3993.fir.kt
new file mode 100644
index 00000000000..764114ff550
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt3993.fir.kt
@@ -0,0 +1,10 @@
+class User(val login : Boolean) {}
+
+fun currentAccess(user: User?): Int {
+    return when {
+        user == null -> 0
+        // We should get smartcast here
+        user.login -> 1 
+        else -> -1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt5427.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt5427.fir.kt
new file mode 100644
index 00000000000..f5315db2e30
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt5427.fir.kt
@@ -0,0 +1,5 @@
+fun foo(p: String?): Int {
+    // We should get smart cast here
+    val x = if (p != null) { p } else "a"
+    return x.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt5455.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt5455.fir.kt
new file mode 100644
index 00000000000..64211fc04e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt5455.fir.kt
@@ -0,0 +1,28 @@
+//KT-5455 Need warning about redundant type cast
+fun foo(o: Any): Int {
+    if (o is String) {
+        return (o as String).length
+    }
+    return -1
+}
+
+open class A {
+    fun foo() {}
+}
+class B: A()
+
+fun test(a: Any?) {
+    if (a is B) {
+        (a as A).foo()
+    }
+}
+
+fun test1(a: B) {
+    (a as A?)?.foo()
+}
+
+fun test2(b: B?) {
+    if (b != null) {
+        (b as A).foo()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt6819.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt6819.fir.kt
new file mode 100644
index 00000000000..0428d84174b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt6819.fir.kt
@@ -0,0 +1,7 @@
+public fun test(o: String?): Boolean {
+    return when {
+        // Data flow info should propagate from o == null to o.length
+        o == null, o.length == 0 -> false
+        else -> true
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/kt7561.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/kt7561.fir.kt
new file mode 100644
index 00000000000..c16095a30dd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/kt7561.fir.kt
@@ -0,0 +1,15 @@
+// Test for a potential byte code mistake for a postfix operation on a smart casted variable
+public fun box() : Int {
+    var i : Int? 
+    i = 10
+    val ii: Int = i
+    // k also should be Int
+    val k : Int = i++
+    // KT-7561: both i and i++ should be Int, otherwise VerifyError can arise here
+    // VerifyError reason: byte code tries to store (i++) result which is Int (smart cast)
+    // into a j which is Int?
+    val j = i++
+    // and m also
+    val m = ++i
+    return j + k + m + i + ii
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaAndArgument.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaAndArgument.fir.kt
new file mode 100644
index 00000000000..9c9803814f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaAndArgument.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+
+inline fun <T> foo(t1: T, t2: T) = t1 ?: t2
+
+inline fun <T> bar(l: (T) -> Unit): T = null!!
+
+fun use() {
+    var x: Int?
+    x = 5
+    // Write is AFTER
+    x.hashCode()
+    // x is nullable at the second argument
+    foo(bar { x = null }, x!!)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaAndArgumentFun.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaAndArgumentFun.fir.kt
new file mode 100644
index 00000000000..393424290e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaAndArgumentFun.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+// See KT-9143: smart cast on a variable nulled inside a lambda argument
+inline fun <T> foo(t1: T, t2: T) = t1 ?: t2
+
+inline fun <T> bar(l: (T) -> Unit): T = null!!
+
+fun use() {
+    var x: Int?
+    x = 5
+    // Write to x is AFTER
+    x.hashCode()
+    // No smart cast should be here!
+    foo(bar { x = null }, x.hashCode())
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentNoSubstitutedReturn.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentNoSubstitutedReturn.fir.kt
new file mode 100644
index 00000000000..fcb5ef96cc1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentNoSubstitutedReturn.fir.kt
@@ -0,0 +1,19 @@
+class Indexed<T>(val x: T, val y: Int)
+
+class Value<out T>(val x: T)
+
+interface WithValue<out T> {
+    fun value(): Value<T>
+}
+
+class Singleton<T>(val x: T) : WithValue<T> {
+    override fun value() = Value(x)
+}
+
+class WithValueIndexed<T>(val f: () -> Value<T>) : WithValue<Indexed<T>> {
+    override fun value() = Value(Indexed(f().x, 0))
+}
+
+fun <T> Singleton<out T>.indexed(): WithValue<Indexed<T>> {
+    return WithValueIndexed { value() }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithBoundWithoutType.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithBoundWithoutType.fir.kt
new file mode 100644
index 00000000000..2dbb729062c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithBoundWithoutType.fir.kt
@@ -0,0 +1,26 @@
+// !WITH_NEW_INFERENCE
+interface Foo
+interface Bar : Foo
+
+fun foo(): Foo? = null
+fun bar(): Bar? = null
+
+fun <T : Bar> run(f: () -> T): T = f()
+
+val foo: Foo = run {
+    val x = bar()
+    if (x == null) throw Exception()
+    x
+}
+
+val foofoo: Foo = run {
+    val x = foo()
+    if (x == null) throw Exception()
+    x
+}
+
+val bar: Bar = run {
+    val x = foo()
+    if (x == null) throw Exception()
+    x
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithExpectedGenericType.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithExpectedGenericType.fir.kt
new file mode 100644
index 00000000000..e466b8b4e9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithExpectedGenericType.fir.kt
@@ -0,0 +1,8 @@
+class My<T: Any>(val y: T?) {
+
+    fun get(): T = run {
+        val x = y
+        if (x == null) throw Exception()
+        x
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutType.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutType.fir.kt
new file mode 100644
index 00000000000..7b2b5b376c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutType.fir.kt
@@ -0,0 +1,20 @@
+// See KT-5385: no smart cast in a literal without given type arguments
+
+interface Foo
+fun foo(): Foo? = null
+
+val foo: Foo = run {
+    val x = foo()
+    if (x == null) throw Exception()
+    x
+}
+
+// Basic non-lambda case
+
+fun <T> repeat(arg: T): T = arg
+
+fun bar(): Foo {
+    val x = foo()
+    if (x == null) throw Exception()
+    return repeat(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeIf.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeIf.fir.kt
new file mode 100644
index 00000000000..e320b6dfccc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeIf.fir.kt
@@ -0,0 +1,13 @@
+// See also KT-7800
+
+fun foo(): Int {
+    val x: Int = 1.let {
+        val value: Int? = null
+        if (value == null) {
+            return@let 1
+        }
+
+        value // smart-cast should be here
+    }
+    return x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeIfMerge.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeIfMerge.fir.kt
new file mode 100644
index 00000000000..8d37f33a443
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeIfMerge.fir.kt
@@ -0,0 +1,14 @@
+// See also KT-7817
+
+fun <R> synchronized(lock: Any, block: () -> R): R = block()
+
+class My {
+    val test: String
+        get() = synchronized(this) {
+            var x: String? = ""
+            if (x == null) {
+                x = "s"
+            }
+            x
+        }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeWhen.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeWhen.fir.kt
new file mode 100644
index 00000000000..b25bc8f4ecb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaArgumentWithoutTypeWhen.fir.kt
@@ -0,0 +1,13 @@
+// See KT-10223
+
+inline fun <T> using(input: Any?, f: (Any?) -> T): T = f(input)
+
+val input: Any? = null
+
+// Error:(32, 24) Type inference failed. Expected type mismatch: inferred type is kotlin.Any? but kotlin.String was expected
+val test4: String = using(input) {
+    when (it) {
+        is String -> it
+        else -> throw RuntimeException()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaCall.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaCall.fir.kt
new file mode 100644
index 00000000000..0f0616ed0e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaCall.fir.kt
@@ -0,0 +1,6 @@
+// See KT-9134: smart cast is not provided inside lambda call
+fun bar(): Int = <!UNRESOLVED_REFERENCE!>{
+    var i: Int?
+    i = 42
+    i
+}()<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaCallAnnotated.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaCallAnnotated.fir.kt
new file mode 100644
index 00000000000..14f7ab96fe5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaCallAnnotated.fir.kt
@@ -0,0 +1,11 @@
+// See KT-9134: smart cast is not provided inside lambda call
+
+@Target(AnnotationTarget.EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class My
+
+fun bar(): Int = @My <!UNRESOLVED_REFERENCE!>{
+    var i: Int?
+    i = 42
+    i
+}()<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifies.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifies.fir.kt
new file mode 100644
index 00000000000..19428eaa994
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifies.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(arg: Int?) {
+    run {
+        var x = arg
+        if (x == null) return@run
+        x.hashCode()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesInLoop.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesInLoop.fir.kt
new file mode 100644
index 00000000000..60e5cb8c9c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesInLoop.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(arg: Int?) {
+    run {
+        var x = arg
+        while (x != null) {
+            x = x.hashCode()
+            if (x == 0) x = null
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesInSecondary.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesInSecondary.fir.kt
new file mode 100644
index 00000000000..9bfbf765432
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesInSecondary.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class My {
+    constructor(arg: Int?) {
+        run {
+            var x = arg
+            if (x == null) return@run
+            x.hashCode()
+        }   
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesWithDirectEq.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesWithDirectEq.fir.kt
new file mode 100644
index 00000000000..e6c59d3ce79
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaDeclaresAndModifiesWithDirectEq.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(arg: Int?) = run {
+    var x = arg
+    if (x == null) return@run
+    x.hashCode()
+}
+
+class My {
+    fun foo(arg: Int?) = run {
+        var x = arg
+        if (x == null) return@run
+        x.hashCode()
+    }
+
+    fun Int?.bar() = run {
+        var x = this
+        if (x == null) return@run
+        x.hashCode()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/lambdaUsesOwnerModifies.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/lambdaUsesOwnerModifies.fir.kt
new file mode 100644
index 00000000000..e33c1f9c5f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/lambdaUsesOwnerModifies.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(arg: Int?) {
+    var x = arg
+    if (x == null) return
+    run {
+        // Not safe: x = null later in the owner
+        x.hashCode()
+    }
+    x = null  
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/level_1_0.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/level_1_0.fir.kt
new file mode 100644
index 00000000000..c171d454ae6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/level_1_0.fir.kt
@@ -0,0 +1,52 @@
+// !LANGUAGE: -SafeCallBoundSmartCasts
+
+fun foo(arg: Int?) {
+    val x = arg
+    if (x != null) {
+        arg.hashCode()
+    }
+    val y: Any? = arg
+    if (y != null) {
+        arg.hashCode()
+    }
+    val yy: Any?
+    yy = arg
+    if (yy != null) {
+        arg.hashCode()
+    }
+    var z = arg
+    z = z?.let { 42 }
+    if (z != null) {
+        arg.hashCode()
+    }
+}
+
+fun kt6840_1(s: String?) {
+    val hash = s?.hashCode()
+    if (hash != null) {
+        s.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
+
+fun kt6840_2(s: String?) {
+    if (s?.hashCode() != null) {
+        s.length
+    }
+}
+
+fun kt1635(s: String?) {
+    s?.hashCode()!!
+    s.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+}
+
+fun kt2127() {
+    val s: String? = ""
+    if (s?.length != null) {
+        s.hashCode()
+    }
+}
+
+fun kt3356(s: String?): Int {
+    if (s?.length != 1) return 0
+    return s.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/localClassChanges.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/localClassChanges.fir.kt
new file mode 100644
index 00000000000..badc7eea0b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/localClassChanges.fir.kt
@@ -0,0 +1,15 @@
+fun trans(n: Int, f: () -> Boolean) = if (f()) n else null
+
+fun foo() {
+    var i: Int? = 5    
+    if (i != null) {
+        class Changing {
+            fun bar() {
+                i = null
+            }
+        }
+        i.hashCode()
+        Changing().bar()
+        i.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/localDelegatedPropertyAfter.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/localDelegatedPropertyAfter.fir.kt
new file mode 100644
index 00000000000..71c37998cfd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/localDelegatedPropertyAfter.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +ProhibitSmartcastsOnLocalDelegatedProperty
+
+class AlternatingDelegate {
+    var counter: Int = 0
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): Any? =
+    if (counter++ % 2 == 0) 42 else ""
+}
+
+fun failsWithClassCastException() {
+    val sometimesNotInt: Any? by AlternatingDelegate()
+
+    if (sometimesNotInt is Int) {
+        sometimesNotInt.inc()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/localDelegatedPropertyBefore.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/localDelegatedPropertyBefore.fir.kt
new file mode 100644
index 00000000000..ef0139a1c22
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/localDelegatedPropertyBefore.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -ProhibitSmartcastsOnLocalDelegatedProperty
+
+class AlternatingDelegate {
+    var counter: Int = 0
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): Any? =
+        if (counter++ % 2 == 0) 42 else ""
+}
+
+fun failsWithClassCastException() {
+    val sometimesNotInt: Any? by AlternatingDelegate()
+
+    if (sometimesNotInt is Int) {
+        sometimesNotInt.inc()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/localFunBetween.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/localFunBetween.fir.kt
new file mode 100644
index 00000000000..cc8959fd1d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/localFunBetween.fir.kt
@@ -0,0 +1,15 @@
+open class Base
+class Derived: Base()
+
+fun bar(derived: Derived) = derived
+
+fun trans(n: Int, f: (Int) -> Boolean) = if (f(n)) n else null
+
+fun foo() {
+    val base: Base = Derived()
+    if (base is Derived) {
+        fun can(n: Int) = n > 0
+        trans(42, ::can)
+        bar(base)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/localFunChanges.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/localFunChanges.fir.kt
new file mode 100644
index 00000000000..ab64f87ef3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/localFunChanges.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+fun trans(n: Int, f: () -> Boolean) = if (f()) n else null
+
+fun foo() {
+    var i: Int? = 5    
+    if (i != null) {
+        fun can(): Boolean {
+            i = null
+            return true
+        }
+        i.hashCode()
+        trans(i, ::can)
+        i.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/localObjectChanges.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/localObjectChanges.fir.kt
new file mode 100644
index 00000000000..fdcd38ed392
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/localObjectChanges.fir.kt
@@ -0,0 +1,15 @@
+fun trans(n: Int, f: () -> Boolean) = if (f()) n else null
+
+fun foo() {
+    var i: Int? = 5    
+    if (i != null) {
+        // Write is AFTER this place
+        i.hashCode()
+        object {
+            fun bar() {
+                i = null
+            }
+        }.bar()
+        i.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/WhileTrueWithBreakInIfCondition.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/WhileTrueWithBreakInIfCondition.fir.kt
new file mode 100644
index 00000000000..6845ef8007c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/WhileTrueWithBreakInIfCondition.fir.kt
@@ -0,0 +1,13 @@
+fun checkJump(x: Int?, y: Int?) {
+    while (true) {
+        if (x ?: break == 0) {
+            y!!
+        } else {
+            y!!
+        }
+        // Ok
+        y.hashCode()
+    }
+    // Smart cast here is erroneous: y is nullable
+    y.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/assignElvisIfBreakInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/assignElvisIfBreakInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..9111346bc48
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/assignElvisIfBreakInsideWhileTrue.fir.kt
@@ -0,0 +1,11 @@
+public fun foo(x: String?, y: String?): Int {
+    while (true) {
+        val z = x ?: if (y == null) break else y
+        // z is not null in both branches
+        z.length
+        // y is nullable if x != null
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    // y is null because of the break
+    return y.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/assignWhenInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/assignWhenInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..0b12ef102a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/assignWhenInsideWhileTrue.fir.kt
@@ -0,0 +1,17 @@
+// !CHECK_TYPE
+
+public fun foo(x: String?): Int {
+    var y: Any
+    loop@ while (true) {
+        y = when (x) {
+            null -> break@loop
+            "abc" -> return 0
+            "xyz" -> return 1
+            else -> x.length
+        }         
+        // y is always Int after when
+        checkSubtype<Int>(y)
+    }    
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakBetweenInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakBetweenInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..a9e1d123967
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakBetweenInsideDoWhile.fir.kt
@@ -0,0 +1,16 @@
+fun bar(): Boolean { return true }
+
+fun gav(w: String, arg: Any, z: String): String 
+{ return if (arg is String) arg else if (z != "") z else w }
+
+public fun foo(x: String?, z: String?, w: String?): Int {
+    do {
+        gav(w!!, if (x == null) break else x, z!!)
+    } while (bar())
+    // w is not null because of w!!
+    w.length
+    // z is nullable despite of z!!
+    z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakFirstInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakFirstInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..d1a1765e5c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakFirstInsideDoWhile.fir.kt
@@ -0,0 +1,13 @@
+fun bar(): Boolean { return true }
+
+fun gav(arg: Any, z: String): String { return if (arg is String) arg else z }
+
+public fun foo(x: String?, z: String?): Int {
+    do {
+        gav(if (x == null) break else x, z!!)
+    } while (bar())
+    // z is nullable despite of z!!
+    z.<!INAPPLICABLE_CANDIDATE!>length<!>
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..a77c2dcad2a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakInsideDoWhile.fir.kt
@@ -0,0 +1,14 @@
+fun bar(): Boolean { return true }
+
+fun gav(arg: Any): String { return if (arg is String) arg else "" }
+
+public fun foo(x: String?): Int {
+    var y: Any
+    do {
+        y = ""
+        y = gav(if (x == null) break else x)
+    } while (bar())
+    y.hashCode()
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakSecondInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakSecondInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..a7b8ba39bb1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakSecondInsideDoWhile.fir.kt
@@ -0,0 +1,13 @@
+fun bar(): Boolean { return true }
+
+fun gav(z: String, arg: Any): String { return if (arg is String) arg else z }
+
+public fun foo(x: String?, z: String?): Int {
+    do {
+        gav(z!!, if (x == null) break else x)
+    } while (bar())
+    // z is not null because of z!!
+    z.length
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakThirdInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakThirdInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..b45f2842eeb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/callBreakThirdInsideDoWhile.fir.kt
@@ -0,0 +1,16 @@
+fun bar(): Boolean { return true }
+
+fun gav(z: String, w: String, arg: Any): String 
+{ return if (arg is String) arg else if (z != "") z else w }
+
+public fun foo(x: String?, z: String?, w: String?): Int {
+    do {
+        gav(z!!, w!!, if (x == null) break else x)
+    } while (bar())
+    // w is not null because of w!!
+    w.length
+    // z is not null because of z!!
+    z.length
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhile.fir.kt
new file mode 100644
index 00000000000..3b245261700
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhile.fir.kt
@@ -0,0 +1,11 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    // See KT-6283
+    do {
+        p!!.length
+    } while (!x())
+    // Do-while loop is executed at least once, so
+    // p should be not null here
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileBreak.fir.kt
new file mode 100644
index 00000000000..6b913fd94a3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileBreak.fir.kt
@@ -0,0 +1,11 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    // See KT-6283
+    do {
+        p!!.length
+        if (p == "abc") break
+    } while (!x())
+    // p should be smart casted despite of break
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileContinue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileContinue.fir.kt
new file mode 100644
index 00000000000..7d95fc89506
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileContinue.fir.kt
@@ -0,0 +1,11 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    // See KT-6283
+    do {
+        p!!.length
+        if (p == "abc") continue
+    } while (!x())
+    // p should be smart casted despite of continue
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileEarlyBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileEarlyBreak.fir.kt
new file mode 100644
index 00000000000..dea1d2e8b1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileEarlyBreak.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+fun y(): Boolean { return false }
+
+public fun foo(p: String?): Int {
+    do {
+        if (y()) break
+        // We do not always reach this statement
+        p!!.length
+    } while (!x())
+    // Here we have do while loop but p is still nullable due to break before
+    return p.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileEarlyContinue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileEarlyContinue.fir.kt
new file mode 100644
index 00000000000..00461db0c84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileEarlyContinue.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+fun y(): Boolean { return false }
+
+public fun foo(p: String?): Int {
+    do {
+        if (y()) continue
+        // We do not always reach this statement
+        p!!.length
+    } while (!x())
+    // Here we have do while loop but p is still nullable due to continue before
+    return p.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileInCondition.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileInCondition.fir.kt
new file mode 100644
index 00000000000..d4a9d4136db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileInCondition.fir.kt
@@ -0,0 +1,5 @@
+fun foo(s: String?): Int {
+    do {
+    } while (s!!.length > 0)
+    return s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileInConditionWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileInConditionWithBreak.fir.kt
new file mode 100644
index 00000000000..5729e3b9e2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileInConditionWithBreak.fir.kt
@@ -0,0 +1,9 @@
+fun bar(): Boolean { return true }
+
+fun foo(s: String?): Int {
+    do {
+        if (bar()) break
+    } while (s!!.length > 0)
+    // This call is unsafe due to break
+    return s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileLiteral.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileLiteral.fir.kt
new file mode 100644
index 00000000000..a9b264cab1b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileLiteral.fir.kt
@@ -0,0 +1,10 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    // Exotic variant with unused literal
+    do { ->
+        p!!.length
+    } while (!x())
+    // Literal is not called so p.length is unsafe
+    return p.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNotNullBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNotNullBreak.fir.kt
new file mode 100644
index 00000000000..8a5997a41d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNotNullBreak.fir.kt
@@ -0,0 +1,10 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    // See KT-6283
+    do {
+        if (p != null) break
+    } while (!x())
+    // p can be null despite of the break
+    return p.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNull.fir.kt
new file mode 100644
index 00000000000..92da461b994
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNull.fir.kt
@@ -0,0 +1,5 @@
+fun foo(s: String?): Int {
+    do {
+    } while (s==null)
+    return s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNullWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNullWithBreak.fir.kt
new file mode 100644
index 00000000000..5692b83191a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/doWhileNullWithBreak.fir.kt
@@ -0,0 +1,9 @@
+fun bar(): Boolean { return true }
+
+fun foo(s: String?): Int {
+    do {
+        if (bar()) break
+    } while (s==null)
+    // This call is unsafe due to break
+    return s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/elvisBreakInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisBreakInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..fdc21aa554b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisBreakInsideDoWhile.fir.kt
@@ -0,0 +1,10 @@
+public fun foo(x: String?): Int {
+    do {
+        // After the check, smart cast should work
+        x ?: break
+        // x is not null in both branches
+        x.length
+    } while (true)
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/elvisIfBreakInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisIfBreakInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..0a74bf6f435
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisIfBreakInsideWhileTrue.fir.kt
@@ -0,0 +1,9 @@
+public fun foo(x: String?, y: String?): Int {
+    while (true) {
+        x ?: if (y == null) break
+        // y is nullable if x != null
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    // y is null because of the break
+    return y.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/elvisInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..8247222dc83
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisInsideDoWhile.fir.kt
@@ -0,0 +1,9 @@
+public fun foo(x: String?): Int {
+    do {
+        // After the check, smart cast should work
+        x ?: x!!.length
+        // x is not null in both branches
+        if (x.length == 0) break
+    } while (true)
+    return x.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/elvisLeftBreakInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisLeftBreakInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..7aa1f53bdca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/elvisLeftBreakInsideWhileTrue.fir.kt
@@ -0,0 +1,9 @@
+public fun foo(x: String?, y: String?): Int {
+    while (true) {
+        (if (x != null) break else y) ?: y!!
+        // y is not null in both branches but it's hard to determine
+        y.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    // y can be null because of the break
+    return y.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/ifBlockInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBlockInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..01d2e73edae
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBlockInsideDoWhile.fir.kt
@@ -0,0 +1,12 @@
+public fun foo(p: String?, y: String?): Int {
+    do {
+        // After the check, smart cast should work
+        if (y == null) {
+            "null".toString()
+            break
+        }
+        y.length
+        p!!.length
+    } while (true)
+    return y?.length ?: -1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakAssignInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakAssignInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..48e4c8a2b03
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakAssignInsideDoWhile.fir.kt
@@ -0,0 +1,14 @@
+fun bar(): Boolean { return true }
+
+public fun foo(x: String?): Int {
+    var y: Any
+    do {
+        // This and hashCode() below are needed just to prevent 
+        // UNINITIALIZED_VARIABLE, UNUSED_VALUE, ...
+        y = "" 
+        y = if (x == null) break else x
+    } while (bar())
+    y.hashCode()
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakAssignInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakAssignInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..3a4519f7069
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakAssignInsideWhileTrue.fir.kt
@@ -0,0 +1,10 @@
+public fun foo(x: String?): Int {
+    var y: Any
+    while (true) {
+        y = if (x == null) break else x
+    }
+    // In future we can infer this initialization
+    y.hashCode()
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakExprInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakExprInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..a3220877033
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/ifBreakExprInsideWhileTrue.fir.kt
@@ -0,0 +1,10 @@
+public fun foo(x: String?): Int {
+    while (true) {
+        // After the check, smart cast should work
+        val y = if (x == null) break else x
+        // y is not null in both branches
+        y.length
+    }
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/ifElseBlockInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/ifElseBlockInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..cade2f2d781
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/ifElseBlockInsideDoWhile.fir.kt
@@ -0,0 +1,15 @@
+public fun foo(x: String?, y: String?): Int {
+    do {
+        // After the check, smart cast should work
+        if (x != null) {
+            if (x == "abc") break
+            y!!.length
+        } else {
+            y!!.length
+        }
+        // y!! in both branches
+        y.length
+    } while (true)
+    // break is possible before so !! is necessary
+    return y!!.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/ifInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/ifInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..a111dc42d93
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/ifInsideDoWhile.fir.kt
@@ -0,0 +1,9 @@
+public fun foo(p: String?, y: String?): Int {
+    do {
+        // After the check, smart cast should work
+        if (y == null) break
+        y.length
+        p!!.length
+    } while (true)
+    return y?.length ?: -1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/leftElvisBreakInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/leftElvisBreakInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..5015104c49a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/leftElvisBreakInsideWhileTrue.fir.kt
@@ -0,0 +1,11 @@
+public fun foo(x: String?, y: String?): Int {
+    while (true) {
+        val z = (if (y == null) break else x) ?: y
+        // z is not null in both branches
+        z.length
+        // y is not null in both branches
+        y.length
+    }
+    // y is null because of the break
+    return y.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/nestedDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedDoWhile.fir.kt
new file mode 100644
index 00000000000..19529e706b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedDoWhile.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?, r: String?): Int {
+    do {
+        do {
+            p!!.length
+        } while (r == null)  
+    } while (!x())
+    // Auto cast possible
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    // Auto cast possible
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/nestedDoWhileWithLongContinue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedDoWhileWithLongContinue.fir.kt
new file mode 100644
index 00000000000..6564b86a853
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedDoWhileWithLongContinue.fir.kt
@@ -0,0 +1,14 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?, r: String?): Int {
+    outer@ do {
+        do {
+            p!!.length
+            if (!x()) continue@outer
+        } while (r == null)  
+    } while (!x())
+    // Auto cast NOT possible due to long continue
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    // Auto cast possible
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoops.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoops.fir.kt
new file mode 100644
index 00000000000..225304cab01
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoops.fir.kt
@@ -0,0 +1,17 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?, r: String?, q: String?): Int {
+    while(true) {
+        q!!.length
+        do {
+            do {
+                p!!.length
+            } while (!x())
+        } while (r == null)
+        if (!x()) break
+    }
+    // Smart cast is possible everywhere
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    q.length
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsShort.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsShort.fir.kt
new file mode 100644
index 00000000000..cdb92f855d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsShort.fir.kt
@@ -0,0 +1,15 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?, r: String?, q: String?): Int {
+    while(true) {
+        q!!.length
+        do {
+            p!!.length
+        } while (r == null)
+        if (!x()) break
+    }
+    // Smart cast is possible everywhere
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    q.length
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithBreak.fir.kt
new file mode 100644
index 00000000000..82a688b33ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithBreak.fir.kt
@@ -0,0 +1,18 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?, r: String?, q: String?): Int {
+    while(true) {
+        q!!.length
+        do {
+            while(true) {
+                p!!.length
+                if (x()) break
+            }
+        } while (r == null)
+        if (!x()) break
+    }
+    // Smart cast is possible everywhere
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    q.length
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithLongBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithLongBreak.fir.kt
new file mode 100644
index 00000000000..a2a469d11d5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithLongBreak.fir.kt
@@ -0,0 +1,20 @@
+fun x(p: String): Boolean { return p == "abc" }
+
+public fun foo(p: String?, r: String?, q: String?): Int {
+    while(true) {
+        q!!.length
+        loop@ do {
+            while(true) {
+                p!!.length
+                if (x(p)) break@loop
+                if (x(q)) break
+            }
+        } while (r == null)
+        if (!x(p)) break
+    }
+    // Long break allows r == null
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    // Smart cast is possible
+    q.length
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithLongContinue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithLongContinue.fir.kt
new file mode 100644
index 00000000000..8cde16df1b4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/nestedLoopsWithLongContinue.fir.kt
@@ -0,0 +1,19 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?, r: String?, q: String?): Int {
+    outer@ while(true) {
+        q!!.length
+        do {
+            if (x()) continue@outer
+            do {
+                p!!.length
+            } while (!x())
+        } while (r == null)
+        if (!x()) break
+    }
+    // Smart cast is possible only for q
+    q.length
+    // But not possible for the others
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/plusAssignWhenInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/plusAssignWhenInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..c19bcee7f8c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/plusAssignWhenInsideDoWhile.fir.kt
@@ -0,0 +1,22 @@
+// !CHECK_TYPE
+
+fun bar(): Boolean { return true }
+
+public fun foo(x: String?): Int {
+    var y: Int?
+    y = 0
+    loop@ do {
+        y += when (x) {
+            null -> break@loop
+            "abc" -> return 0
+            "xyz" -> return 1
+            else -> x.length
+        }         
+        // y is always Int after when
+        checkSubtype<Int>(y)
+    } while (bar())
+    // y is always Int even here
+    checkSubtype<Int>(y)
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/safeCallBreakInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/safeCallBreakInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..c4a3c5e1d0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/safeCallBreakInsideDoWhile.fir.kt
@@ -0,0 +1,14 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?, y: String?): Int {
+    do {
+        // Smart cast because of x!! in receiver
+        foo(x!!)?.subSequence(0, if (x.length > 0) 5 else break)
+        y!!.length
+        // x is not null in condition but we do not see it yet
+    } while (x.length > 0)
+    // y is nullable because of break
+    y.length
+    // x is not null, at least in theory
+    return x.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/safeCallInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/safeCallInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..5f301359454
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/safeCallInsideDoWhile.fir.kt
@@ -0,0 +1,12 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?): Int {
+    do {
+        // Smart cast because of x!! in receiver
+        foo(x!!)?.subSequence(0, x.length)
+        // Smart cast because of x!! in receiver
+        if (x.length == 0) break
+    } while (true)
+    // Here x is also not null
+    return x.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/useInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/useInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..ddc8e8f03d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/useInsideDoWhile.fir.kt
@@ -0,0 +1,9 @@
+public fun foo(p: String?, y: String?): Int {
+    do {
+        // After this !!, y. should be smartcasted in loop as well as outside
+        y!!.length
+        if (p == null) break
+        y.length
+    } while (true)
+    return y.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whenInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whenInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..28f75d8ae24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whenInsideWhileTrue.fir.kt
@@ -0,0 +1,12 @@
+public fun foo(x: String?): Int {
+    loop@ while (true) {
+        when (x) {
+            null -> break@loop
+            "abc" -> return 0
+            "xyz" -> return 1
+            else -> x.length
+        }         
+    }
+    // x is null because of the break
+    return x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whenReturnInsideWhileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whenReturnInsideWhileTrue.fir.kt
new file mode 100644
index 00000000000..07ffb4833d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whenReturnInsideWhileTrue.fir.kt
@@ -0,0 +1,13 @@
+public fun foo(x: String?): Int {
+    loop@ while (true) {
+        when (x) {
+            null -> return -1
+            "abc" -> return 0
+            "xyz" -> return 1
+            else -> break@loop
+        }         
+    }
+    // x is not null because of the break
+    // but we are not able to detect it
+    return x.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileInCondition.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileInCondition.fir.kt
new file mode 100644
index 00000000000..f3f5223aa45
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileInCondition.fir.kt
@@ -0,0 +1,6 @@
+fun foo(s: String?): Int {
+    while (s!!.length > 0) {
+        s.length
+    }
+    return s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileInConditionWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileInConditionWithBreak.fir.kt
new file mode 100644
index 00000000000..8cf1d3e44ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileInConditionWithBreak.fir.kt
@@ -0,0 +1,9 @@
+fun bar(): Boolean { return true }
+
+fun foo(s: String?): Int {
+    while (s!!.length > 0) {
+        s.length
+        if (bar()) break
+    }
+    return s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileNull.fir.kt
new file mode 100644
index 00000000000..1482762bde8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileNull.fir.kt
@@ -0,0 +1,5 @@
+fun foo(s: String?): Int {
+    while (s==null) {
+    }
+    return s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileNullAssignToSomething.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileNullAssignToSomething.fir.kt
new file mode 100644
index 00000000000..276b68eeccc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileNullAssignToSomething.fir.kt
@@ -0,0 +1,9 @@
+fun main() {
+    var result: String? = null
+    var i = 0
+    while (result == null) {
+        if (i == 10) result = "non null"
+        else i++
+    }
+    result.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileNullWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileNullWithBreak.fir.kt
new file mode 100644
index 00000000000..c52d962227f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileNullWithBreak.fir.kt
@@ -0,0 +1,9 @@
+fun bar(): Boolean { return true }
+
+fun foo(s: String?): Int {
+    while (s==null) {
+        if (bar()) break
+    }
+    // Call is unsafe due to break
+    return s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileSimple.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileSimple.fir.kt
new file mode 100644
index 00000000000..cfe59782992
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileSimple.fir.kt
@@ -0,0 +1,10 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {    
+    while(x()) {
+        p!!.length
+        if (x()) break
+    }
+    // p is nullable because it's possible loop body is not executed at all
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrivial.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrivial.fir.kt
new file mode 100644
index 00000000000..3eeedc78531
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrivial.fir.kt
@@ -0,0 +1,11 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    // Like whileTrue but 2 == 2 is in use
+    while(2 == 2) {
+        p!!.length
+        if (x()) break
+    }
+    // Smart cast should not work in this case, see KT-6284
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrue.fir.kt
new file mode 100644
index 00000000000..8c2d11b4383
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrue.fir.kt
@@ -0,0 +1,12 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    // KT-6284
+    while(true) {
+        p!!.length
+        if (x()) break
+    }
+    // while (true) loop body is executed at least once
+    // so p is not null here
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueBreakReturn.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueBreakReturn.fir.kt
new file mode 100644
index 00000000000..26d79bd116d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueBreakReturn.fir.kt
@@ -0,0 +1,12 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    while(true) {
+        if (x()) break
+        if (p==null) return -1
+        // p is not null
+        p.length
+    }
+    // p can be null because break is earlier than return
+    return p.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueEarlyBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueEarlyBreak.fir.kt
new file mode 100644
index 00000000000..08daf2b657e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueEarlyBreak.fir.kt
@@ -0,0 +1,11 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    while(true) {
+        if (x()) break
+        // We do not always reach this statement
+        p!!.length
+    }
+    // Here we have while (true) loop but p is nullable due to break before
+    return p.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueReturn.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueReturn.fir.kt
new file mode 100644
index 00000000000..8bd84422c70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileTrueReturn.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(p: String?): Int {
+    while(true) {
+        if (p==null) return -1
+        if (x()) break
+        // p is not null
+        p.length
+    }
+    // while (true) loop body with return is executed at least once
+    // so p is not null here
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakAfter.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakAfter.fir.kt
new file mode 100644
index 00000000000..949f54a32c9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakAfter.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +SoundSmartcastFromLoopConditionForLoopAssignedVariables
+
+fun foo() {
+    var x: String? = "123"
+    while (x!!.length < 42) {
+        x = null
+        break
+
+    }
+    // TODO: this testdata fixates undesired behavior (it should be an unsafe call)
+    x.<!UNRESOLVED_REFERENCE!>length<!> // 'x' is unsoundly smartcasted here
+}
+
+fun bar() {
+    var x: List<Int>? = ArrayList<Int>(1)
+    for (i in x!!) {
+        x = null
+        break
+
+    }
+    // TODO: this testdata fixates undesired behavior (it should be an unsafe call)
+    x.<!UNRESOLVED_REFERENCE!>size<!> // 'x' is unsoundly smartcasted here
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakBefore.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakBefore.fir.kt
new file mode 100644
index 00000000000..0b651c5beea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/loops/whileWithAssertInConditionAndBreakBefore.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: -SoundSmartcastFromLoopConditionForLoopAssignedVariables
+
+fun foo() {
+    var x: String? = "123"
+    while (x!!.length < 42) {
+        x = null
+        break
+
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!> // 'x' is unsoundly smartcasted here
+}
+
+fun bar() {
+    var x: List<Int>? = ArrayList<Int>(1)
+    for (i in x!!) {
+        x = null
+        break
+
+    }
+    x.<!UNRESOLVED_REFERENCE!>size<!> // 'x' is unsoundly smartcasted here
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/multipleResolvedCalls.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/multipleResolvedCalls.fir.kt
new file mode 100644
index 00000000000..e5b0430f05a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/multipleResolvedCalls.fir.kt
@@ -0,0 +1,19 @@
+interface I1
+interface I2
+interface I3
+interface I4
+interface I5
+
+operator fun I1.component1() = 1
+operator fun I2.component2() = 2
+operator fun I3.component3() = 3
+operator fun I4.component4() = 4
+operator fun I5.component5() = 5
+
+fun test(x: Any): Int {
+    if (x is I1 && x is I2 && x is I3 && x is I4 && x is I5) {
+        val (t1, t2, t3, t4, t5) = x
+        return t1 + t2 + t3 + t4 + t5
+    }
+    else return 0
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/noErrorCheckForPackageLevelVal.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/noErrorCheckForPackageLevelVal.fir.kt
new file mode 100644
index 00000000000..4cba8e94eee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/noErrorCheckForPackageLevelVal.fir.kt
@@ -0,0 +1,25 @@
+//FILE: bar.kt
+package bar
+
+val i: Int? = 2
+
+//FILE: foo.kt
+package foo
+
+val i: Int? = 1
+
+class A(val i: Int?) {
+    fun testUseFromClass() {
+        if (foo.i != null) {
+            useInt(i)
+        }
+    }
+}
+
+fun testUseFromOtherPackage() {
+    if (bar.i != null) {
+        useInt(i)
+    }
+}
+
+fun useInt(i: Int) = i
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/noUnnecessarySmartCastForReceiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/noUnnecessarySmartCastForReceiver.fir.kt
new file mode 100644
index 00000000000..9a38cbf1172
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/noUnnecessarySmartCastForReceiver.fir.kt
@@ -0,0 +1,7 @@
+fun Any?.foo() {}
+
+fun test(a: Any?) {
+    if (a != null) {
+        a.foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/notNullorNotNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/notNullorNotNull.fir.kt
new file mode 100644
index 00000000000..5fc238ca174
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/notNullorNotNull.fir.kt
@@ -0,0 +1,6 @@
+fun bar(x: Int?): Int {
+    if (x != null) return -1
+    if (x == null) return -2
+    // Should be unreachable
+    return 2 + 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/assignment.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/assignment.fir.kt
new file mode 100644
index 00000000000..b6b86473309
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/assignment.fir.kt
@@ -0,0 +1,19 @@
+// See KT-6293: Smart cast doesn't work after object literal
+abstract class Runnable {
+    abstract fun run()
+}
+
+fun foo(): Int {
+    val c: Int? = null
+    if (c is Int) {
+        var k: Runnable
+        val d: Int = c
+        k = object: Runnable() {
+            override fun run() = Unit
+        }
+        // Unnecessary but not important smart cast
+        k.run()
+        return c + d
+    }
+    else return -1
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/base.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/base.fir.kt
new file mode 100644
index 00000000000..61491a9761a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/base.fir.kt
@@ -0,0 +1,19 @@
+// See KT-6293: Smart cast doesn't work after object literal
+abstract class Runnable {
+    abstract fun run()
+}
+
+fun foo(): Int {
+    val c: Int? = null
+    if (c is Int) {
+        val d: Int = c
+        // This object breaks data flow info propagation
+        val k = object: Runnable() {
+            override fun run() = Unit
+        }
+        k.run()
+        // Smart cast should work but error is reported
+        return c + d
+    }
+    else return -1
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/captured.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/captured.fir.kt
new file mode 100644
index 00000000000..e720d23fd1e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/captured.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+abstract class Runnable {
+    abstract fun run()
+}
+
+fun foo(): Int {
+    val c: Int? = null
+    var a: Int?
+    if (c is Int) {
+        a = 2
+        val k = object: Runnable() {
+            init {
+                a = null
+            }
+            override fun run() = Unit
+        }
+        k.run()
+        val d: Int = c
+        // a is captured so smart cast is not possible
+        return d + a
+    }
+    else return -1
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexcl.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexcl.fir.kt
new file mode 100644
index 00000000000..a6e7d8391bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexcl.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+abstract class Runnable {
+    abstract fun run()
+}
+
+fun foo(): Int {
+    val c: Int? = null
+    val a: Int? = 1
+    if (c is Int) {
+        val k = object: Runnable() {
+            init {
+                a!!.toInt()
+            }
+            override fun run() = Unit
+        }
+        k.run()
+        val d: Int = c
+        // a is not null because of k constructor, but we do not know it
+        return a <!INAPPLICABLE_CANDIDATE!>+<!> d
+    }
+    else return -1
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclArgument.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclArgument.fir.kt
new file mode 100644
index 00000000000..98186b9a1c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclArgument.fir.kt
@@ -0,0 +1,17 @@
+abstract class Runnable(val arg: Int) {
+    abstract fun run(): Int
+}
+
+fun foo(): Int {
+    val c: Int? = null
+    val a: Int? = 1
+    if (c is Int) {
+        val k = object: Runnable(a!!) {
+            override fun run() = arg
+        }
+        k.run()
+        val d: Int = c
+        return a <!INAPPLICABLE_CANDIDATE!>+<!> d
+    }
+    else return -1
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclTwoArgument.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclTwoArgument.fir.kt
new file mode 100644
index 00000000000..0ed5e29c566
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/exclexclTwoArgument.fir.kt
@@ -0,0 +1,21 @@
+abstract class Runnable(val arg: Int) {
+    abstract fun run(): Int
+}
+
+interface Wrapper {
+    fun run(): Int
+}
+
+fun foo(): Int {
+    val c: Int? = null
+    val a: Int? = 1
+    if (c is Int) {
+        val k = object: Wrapper, Runnable(a!!) {
+            override fun run() = arg
+        }
+        k.run()
+        val d: Int = c
+        return a <!INAPPLICABLE_CANDIDATE!>+<!> d
+    }
+    else return -1
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/kt7110.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/kt7110.fir.kt
new file mode 100644
index 00000000000..9db5e130a9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/kt7110.fir.kt
@@ -0,0 +1,11 @@
+//  Anonymous object's initialization does not affect smart casts
+
+abstract class A(val s: String) {
+    fun bar(): String = s
+}
+
+fun foo(o: String?): Int {
+    val a = object : A(o!!){}
+    a.bar()
+    return o.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/receiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/receiver.fir.kt
new file mode 100644
index 00000000000..b741cb13a11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/objectLiterals/receiver.fir.kt
@@ -0,0 +1,16 @@
+// See KT-6293: Smart cast doesn't work after object literal
+abstract class Runnable {
+    abstract fun run()
+}
+
+fun foo(): Int {
+    val c: Int? = null
+    if (c is Int) {
+        val d: Int = c
+        object: Runnable() {
+            override fun run() = Unit
+        }.run()
+        return c + d
+    }
+    else return -1
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/openInSealed.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/openInSealed.fir.kt
new file mode 100644
index 00000000000..8b0160f3ba6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/openInSealed.fir.kt
@@ -0,0 +1,8 @@
+sealed class My(open val x: Int?) {
+    init {
+        if (x != null) {
+            // Should be error: property is open
+            x.hashCode()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/ownerDeclaresBothModifies.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/ownerDeclaresBothModifies.fir.kt
new file mode 100644
index 00000000000..e6df621d176
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/ownerDeclaresBothModifies.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+fun foo(arg: Int?) {
+    var x = arg
+    if (x == null) return
+    run {
+        // Unsafe because of owner modification
+        x.hashCode()
+        x = null
+    }
+    if (x != null) x = 42
+    // Unsafe because of lambda
+    x.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/propertyAsCondition.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/propertyAsCondition.fir.kt
new file mode 100644
index 00000000000..bb0861c837a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/propertyAsCondition.fir.kt
@@ -0,0 +1,30 @@
+// See also: KT-11998
+data class My(val x: Boolean?)
+
+fun doIt() {}
+
+fun foo(my: My) {
+    if (my.x != null) {
+        // my.x should be smart-cast
+        if (my.x) doIt()
+        when (my.x) {
+            true -> doIt()
+        }
+        when {
+            my.x -> doIt()
+        }
+    }
+}
+
+fun bar(x: Boolean?) {
+    if (x != null) {
+        // x should be smart-cast
+        if (x) doIt()
+        when (x) {
+            true -> doIt()
+        }
+        when {
+            x -> doIt()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/propertyToNotNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/propertyToNotNull.fir.kt
new file mode 100644
index 00000000000..7b54582ba92
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/propertyToNotNull.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+class Immutable(val x: String?) {
+    fun foo(): String {
+        if (x != null) return x
+        return ""
+    }
+}
+
+class Mutable(var y: String?) {
+    fun foo(): String {
+        if (y != null) return y
+        return ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/customGetter.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/customGetter.fir.kt
new file mode 100644
index 00000000000..094ffda8ced
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/customGetter.fir.kt
@@ -0,0 +1,13 @@
+public class X {
+    private val x : String? = null
+    public val y: CharSequence?
+        get() = x?.subSequence(0, 1)
+    public fun fn(): Int {
+        if (y != null)
+            // With non-default getter smartcast is not possible
+            return y.length
+        else
+            return 0
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/delegate.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/delegate.fir.kt
new file mode 100644
index 00000000000..e589ef8a50a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/delegate.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+import kotlin.reflect.KProperty
+
+class Delegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String? {
+        return null
+    }
+}
+
+class Example {
+    private val p: String? by Delegate()
+
+    public val r: String? = "xyz"
+
+    public fun foo(): String {
+        // Smart cast is not possible if property is delegated
+        return if (p != null) p else ""
+    }
+
+    public fun bar(): String {
+        // But is possible for non-delegated value property even if it's public
+        return if (r != null) r else ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/kt4409.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/kt4409.fir.kt
new file mode 100644
index 00000000000..66d57db2a66
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/kt4409.fir.kt
@@ -0,0 +1,13 @@
+public interface A {
+    public val x: Any
+}
+
+public class B(override public val x: Any) : A {
+    fun foo(): Int {
+        if (x is String) {
+            return x.length
+        } else {
+            return 0
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/kt5502.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/kt5502.fir.kt
new file mode 100644
index 00000000000..9cf8732a1d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/kt5502.fir.kt
@@ -0,0 +1,16 @@
+// NB: should work after KT-5907 / KT-4450 fix
+
+val currentTimeMillis = 1234L
+
+public class Foo(protected val maxParsingTimeInMillis: Long?) {
+
+    var parsingStartTimeStamp = 0L
+
+    protected fun checkForParsingTimeout(): Boolean {
+        if (maxParsingTimeInMillis == null)
+            return true
+        if (currentTimeMillis - parsingStartTimeStamp > maxParsingTimeInMillis)
+            return false
+        return true
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/open.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/open.fir.kt
new file mode 100644
index 00000000000..cb56a5826d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/open.fir.kt
@@ -0,0 +1,11 @@
+public open class A() {
+    public open val foo: Int? = 1
+}
+
+infix fun Int.bar(i: Int) = i
+
+fun test() {
+    val p = A()
+    // For open value properties, smart casts should not work
+    if (p.foo is Int) p.foo bar 11
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/otherModule.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/otherModule.fir.kt
new file mode 100644
index 00000000000..3b467593ed3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/otherModule.fir.kt
@@ -0,0 +1,35 @@
+// MODULE: m1
+// FILE: a.kt
+
+package a
+
+public class X {
+    public val x : String? = null
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+package b
+
+import a.X
+
+public fun X.gav(): Int {
+    if (x != null)
+        // Smart cast is not possible if definition is in another module
+        return x.length
+    else
+        return 0
+}
+
+// FILE: c.kt
+
+package a
+
+public fun X.gav(): Int {
+    if (x != null)
+        // Even if it's in the same package
+        return x.length
+    else
+        return 0
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/protected.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/protected.fir.kt
new file mode 100644
index 00000000000..72e2a2cee5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/protected.fir.kt
@@ -0,0 +1,17 @@
+public open class X {
+    protected val x : String? = null
+    public fun fn(): Int {
+        if (x != null)
+            // Smartcast is possible for protected value property in the same class
+            return x.length
+        else
+            return 0
+    }
+}
+
+public class Y: X() {
+    public fun bar(): Int {
+        // Smartcast is possible even in derived class
+        return if (x != null) x.length else 0
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/simple.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/simple.fir.kt
new file mode 100644
index 00000000000..f831485d65d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/simple.fir.kt
@@ -0,0 +1,12 @@
+public class X {
+    public val x : String? = null
+    public fun fn(): Int {
+        if (x != null)
+            // Smartcast is possible because it's value property with default getter
+            // used in the same module
+            return x.length
+        else
+            return 0
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/publicVals/var.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/publicVals/var.fir.kt
new file mode 100644
index 00000000000..ffff8aba67a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/publicVals/var.fir.kt
@@ -0,0 +1,15 @@
+public class X {
+    public var x : String? = null
+    private var y: String? = "abc"
+    public fun fn(): Int {
+        if (x != null)
+            // Smartcast is not possible for variable properties
+            return x.length
+        else if (y != null)
+            // Even if they are private
+            return y.length
+        else
+            return 0
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safeAs.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safeAs.fir.kt
new file mode 100644
index 00000000000..c5e38bcad56
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safeAs.fir.kt
@@ -0,0 +1,17 @@
+// See also KT-10992: we should have no errors for all unsafe hashCode() calls
+
+fun foo(arg: Any?) {
+    val x = arg as? Any ?: return
+    arg.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    x.hashCode()
+}
+
+fun bar(arg: Any?) {
+    arg as? Any ?: return
+    arg.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+}
+
+fun gav(arg: Any?) {
+    arg as? String ?: return
+    arg.<!UNRESOLVED_REFERENCE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/anotherVal.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/anotherVal.fir.kt
new file mode 100644
index 00000000000..c8e1e81570d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/anotherVal.fir.kt
@@ -0,0 +1,8 @@
+// !WITH_NEW_INFERENCE
+
+fun calc(x: List<String>?, y: Int?): Int {
+    x?.get(y!! - 1) 
+    // y!! above should not provide smart cast here
+    val yy: Int = y
+    return  yy + (x?.size ?: 0)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/argument.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/argument.fir.kt
new file mode 100644
index 00000000000..381263e32e8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/argument.fir.kt
@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // After KT-5840 fix !! assertion should become unnecessary here
+    x?.get(x!!.size - 1)
+    // x?. or x!! above should not provide smart cast here
+    return x.<!INAPPLICABLE_CANDIDATE!>size<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainAndUse.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainAndUse.fir.kt
new file mode 100644
index 00000000000..9942d29c85b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainAndUse.fir.kt
@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list, despite of a chain
+    x?.subList(0, 1)?.get(x.size)
+    // But not here!
+    return x!!.size
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainInChain.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainInChain.fir.kt
new file mode 100644
index 00000000000..b9f9fe049c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainInChain.fir.kt
@@ -0,0 +1,6 @@
+fun calc(x: List<String>?, y: List<Int>?) {
+    // x and y should be non-null in arguments list, despite of a chains
+    x?.subList(y?.subList(1, 2)?.get(y.size) ?: 0,
+               y?.get(0) ?: 1) // But safe call is NECESSARY here for y
+     ?.get(x.size)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainMixedUnsafe.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainMixedUnsafe.fir.kt
new file mode 100644
index 00000000000..188d1a4eb5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/chainMixedUnsafe.fir.kt
@@ -0,0 +1,5 @@
+fun calc(x: List<String>?): Int {
+    // x is not-null only inside subList
+    x?.subList(0, x.size - 1).<!INAPPLICABLE_CANDIDATE!>get<!>(x.<!INAPPLICABLE_CANDIDATE!>size<!>)
+    return x!!.size
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/doubleCall.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/doubleCall.fir.kt
new file mode 100644
index 00000000000..5590814b6c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/doubleCall.fir.kt
@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list, including inner call
+    x?.get(x.get(x.size - 1).length)
+    // but not also here!
+    return x.<!INAPPLICABLE_CANDIDATE!>size<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/extension.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/extension.fir.kt
new file mode 100644
index 00000000000..e953979c425
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/extension.fir.kt
@@ -0,0 +1,6 @@
+fun String.foo(arg: Int) = this[arg]
+
+fun calc(x: String?) {
+    // x should be non-null in arguments list
+    x?.foo(x.length - 1)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/extensionCall.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/extensionCall.fir.kt
new file mode 100644
index 00000000000..d40d400286f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/extensionCall.fir.kt
@@ -0,0 +1,6 @@
+fun String.bar(s: String) = s
+
+fun foo(s: String?) {
+    s?.bar(s)
+    s?.get(s.length)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseArgument.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseArgument.fir.kt
new file mode 100644
index 00000000000..ae1b9ea8cd5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseArgument.fir.kt
@@ -0,0 +1,7 @@
+fun foo(y: Int) = y
+
+fun calc(x: List<String>?): Int {
+    foo(x!!.size)
+    // Here we should have smart cast because of x!!, despite of KT-7204 fixed
+    return x.size
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseChain.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseChain.fir.kt
new file mode 100644
index 00000000000..314b1002ee4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseChain.fir.kt
@@ -0,0 +1,4 @@
+fun calc(x: List<String>?, y: Int?) {
+    // Smart cast should work here despite of KT-7204 fixed
+    x?.subList(0, y!!)?.get(y) 
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseExtension.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseExtension.fir.kt
new file mode 100644
index 00000000000..4b7fe96a863
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseExtension.fir.kt
@@ -0,0 +1,7 @@
+fun String.foo(y: Int) = y
+
+fun calc(x: List<String>?): Int {
+    "abc".foo(x!!.size)
+    // Here we should have smart cast because of x!!, despite of KT-7204 fixed
+    return x.size
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseSecondArgument.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseSecondArgument.fir.kt
new file mode 100644
index 00000000000..91ac2daecbd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/falseSecondArgument.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+
+fun calc(x: List<String>?, y: Int?): Int {
+    x?.subList(y!! - 1, y)
+    // y!! above should not provide smart cast here
+    return y
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/innerReceiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/innerReceiver.fir.kt
new file mode 100644
index 00000000000..b1016ada479
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/innerReceiver.fir.kt
@@ -0,0 +1,8 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?, y: String?): Int {
+    // Smart cast because of y!! in receiver
+    x?.subSequence(y!!.subSequence(0, 1).length, y.length)
+    // No smart cast possible
+    return y.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/insideCall.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/insideCall.fir.kt
new file mode 100644
index 00000000000..054e32c21f4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/insideCall.fir.kt
@@ -0,0 +1,8 @@
+fun foo(y: Int): Int {
+    return y + 1
+}
+
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list
+    return foo(x?.get(x.size - 1)!!.length)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/insideIfExpr.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/insideIfExpr.fir.kt
new file mode 100644
index 00000000000..4593c469564
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/insideIfExpr.fir.kt
@@ -0,0 +1,43 @@
+// See KT-11007: Wrong smart cast to not-null type after safe calls in if / when expression
+
+val String.copy: String
+    get() = this
+
+fun foo() {
+    val s: String? = null
+    val ss = if (true) {
+        s?.length
+    } else {
+        s?.length
+    }
+    ss.<!INAPPLICABLE_CANDIDATE!>hashCode<!>() // Smart-cast to Int, should be unsafe call
+    val sss = if (true) {
+        s?.copy
+    }
+    else {
+        s?.copy
+    }
+    sss.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+class My {
+    val String.copy2: String
+        get() = this
+
+    fun foo() {
+        val s: String? = null
+        val ss = if (true) {
+            s?.length
+        } else {
+            s?.length
+        }
+        ss.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        val sss = if (true) {
+            s?.copy2
+        }
+        else {
+            s?.copy2
+        }
+        sss.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/longChain.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/longChain.fir.kt
new file mode 100644
index 00000000000..e72c14c1a71
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/longChain.fir.kt
@@ -0,0 +1,6 @@
+fun calc(x: List<String>?) {
+    // x should be non-null in arguments list, despite of a chain
+    x?.subList(0, x.size)?.
+       subList(0, x.size)?.
+       get(x.size)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiver.fir.kt
new file mode 100644
index 00000000000..fc765b7bd64
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiver.fir.kt
@@ -0,0 +1,13 @@
+// See KT-10056
+class Foo(val bar: String)
+
+fun test(foo: Foo?) {
+    foo?.bar.let {
+        // Error, foo?.bar is nullable
+        it.<!INAPPLICABLE_CANDIDATE!>length<!>
+        // Error, foo is nullable
+        foo.<!INAPPLICABLE_CANDIDATE!>bar<!>.<!UNRESOLVED_REFERENCE!>length<!>
+        // Correct
+        foo?.bar?.length
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverInLongChain.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverInLongChain.fir.kt
new file mode 100644
index 00000000000..eaa94bcd0f5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverInLongChain.fir.kt
@@ -0,0 +1,42 @@
+class Bar(val gav: String)
+
+class Foo(val bar: Bar, val nbar: Bar?) {
+    fun baz(s: String) = if (s != "") Bar(s) else null
+}
+
+fun String?.call(f: (String?) -> String?) = f(this)
+
+fun String.notNullLet(f: (String) -> Unit) = f(this)
+
+fun test(foo: Foo?) {
+    foo?.bar?.gav.let {
+        // Error, foo?.bar?.gav is nullable
+        it.<!INAPPLICABLE_CANDIDATE!>length<!>
+        // Error, foo is nullable
+        foo.<!INAPPLICABLE_CANDIDATE!>bar<!>.<!UNRESOLVED_REFERENCE!>gav<!>.<!UNRESOLVED_REFERENCE!>length<!>
+        // Correct
+        foo?.bar?.gav?.length
+    }
+    foo?.bar?.gav.call { it }?.notNullLet {
+        foo.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        foo.<!INAPPLICABLE_CANDIDATE!>bar<!>.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+    }
+}
+
+fun testNotNull(foo: Foo) {
+    val s: String? = ""
+    foo.baz(s!!)?.gav.let {
+        it.<!INAPPLICABLE_CANDIDATE!>length<!>
+        // Ok because of foo.
+        s.length.hashCode()
+    }
+}
+
+fun testNullable(foo: Foo?) {
+    val s: String? = ""
+    foo?.baz(s!!)?.gav.let {
+        it.<!INAPPLICABLE_CANDIDATE!>length<!>
+        // Ok because of foo?.
+        s?.length?.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithExclExcl.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithExclExcl.fir.kt
new file mode 100644
index 00000000000..a3800971019
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithExclExcl.fir.kt
@@ -0,0 +1,11 @@
+class Foo(val bar: String?)
+
+fun test(foo: Foo?) {
+    foo!!.bar.let {
+        // Correct
+        foo.bar?.length
+        // Unnecessary
+        foo?.bar?.length
+    }
+    foo.bar?.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithFlexible.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithFlexible.fir.kt
new file mode 100644
index 00000000000..0743b51b49d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithFlexible.fir.kt
@@ -0,0 +1,25 @@
+// FILE: Foo.java
+public class Foo {
+    public String bar;
+
+    private Foo(String bar) {
+        this.bar = bar;
+    }
+
+    public static Foo create(String bar) {
+        return new Foo(bar);
+    }
+}
+
+// FILE: Test.kt
+fun test() {
+    val foo = Foo.create(null)
+    foo?.bar.let {
+        // Error, foo?.bar is nullable
+        it.<!INAPPLICABLE_CANDIDATE!>length<!>
+        // Foo is nullable but flexible, so call is considered safe here
+        foo.bar.length
+        // Correct
+        foo?.bar?.length
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/property.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/property.fir.kt
new file mode 100644
index 00000000000..626690ecb20
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/property.fir.kt
@@ -0,0 +1,6 @@
+data class MyClass(val x: String?)
+
+fun foo(y: MyClass): Int {
+    val z = y.x?.subSequence(0, y.x.length)
+    return z?.length ?: -1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/propertyChain.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/propertyChain.fir.kt
new file mode 100644
index 00000000000..1cf8604ce26
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/propertyChain.fir.kt
@@ -0,0 +1,14 @@
+// See KT-7290
+class MyClass(val x: String?)
+fun foo(y: MyClass?): Int {
+    // x here is smartcast but y is not
+    val z = y?.x?.subSequence(0, y.x.length)
+    // !! is necessary here
+    y!!.x
+    return z?.length ?: -1
+}
+fun bar(y: MyClass?) {
+    y?.x!!.length
+    // !! is NOT necessary here, because y?.x != null
+    y!!.x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiver.fir.kt
new file mode 100644
index 00000000000..22f9dbd5fd3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiver.fir.kt
@@ -0,0 +1,8 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?): Int {
+    // Smart cast because of x!! in receiver
+    foo(x!!)?.subSequence(0, x.length)
+    // Smart cast because of x!! in receiver
+    return x.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChain.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChain.fir.kt
new file mode 100644
index 00000000000..550cbf63d58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChain.fir.kt
@@ -0,0 +1,8 @@
+fun foo(x: String): String? = x
+
+fun calc(x: String?): Int {
+    // Smart cast because of x!! in receiver
+    foo(x!!)?.subSequence(0, x.length)?.length
+    // Smart cast because of x!! in receiver
+    return x.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChainFalse.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChainFalse.fir.kt
new file mode 100644
index 00000000000..347cb784791
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/receiverAndChainFalse.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+
+fun foo(x: String): String? = x
+
+fun calc(x: String?, y: Int?): Int {
+    // Smart cast because of x!! in receiver
+    foo(x!!)?.subSequence(y!!, x.length)?.length
+    // No smart cast possible
+    return y
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/safeAccessReceiverNotNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/safeAccessReceiverNotNull.fir.kt
new file mode 100644
index 00000000000..6434bbd9bd8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/safeAccessReceiverNotNull.fir.kt
@@ -0,0 +1,136 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: -SafeCastCheckBoundSmartCasts -BooleanElvisBoundSmartCasts
+// A set of examples for
+// "If the result of a safe call is not null, understand that its receiver is not null"
+// and some other improvements for nullability detection
+
+fun kt6840_1(s: String?) {
+    val hash = s?.hashCode()
+    if (hash != null) {
+        s.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
+
+fun kt6840_2(s: String?) {
+    if (s?.hashCode() != null) {
+        s.length
+    }
+}
+
+fun kt1635(s: String?) {
+    s?.hashCode()!!
+    s.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+}
+
+fun kt2127() {
+    val s: String? = ""
+    if (s?.length != null) {
+        s.hashCode()
+    }
+}
+
+fun kt3356(s: String?): Int {
+    if (s?.length != 1) return 0
+    return s.length
+}
+
+open class SomeClass(val data: Any)
+
+class SubClass(val extra: Any, data: Any) : SomeClass(data)
+
+fun kt4565_1(a: SomeClass?) {
+    val data = a?.data
+    if (data != null) {
+        data.hashCode()
+        a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        a.<!INAPPLICABLE_CANDIDATE!>data<!>.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+    }
+    if (a?.data != null) {
+        // To be supported (?!)
+        data.hashCode()
+        a.hashCode()
+        a.data.hashCode()
+    }
+    if (a?.data is String) {
+        a.<!INAPPLICABLE_CANDIDATE!>data<!>.<!UNRESOLVED_REFERENCE!>length<!>
+        data.length
+    }
+}
+
+fun kt4565_2(a: SomeClass?) {
+    // To be supported
+    if (a as? SubClass != null) {
+        a.extra.hashCode()
+    }
+    val extra = (a as? SubClass)?.extra
+    if (extra != null) {
+        a.<!UNRESOLVED_REFERENCE!>extra<!>.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+    }
+}
+
+class A(val y: Int)
+
+fun kt7491_1() {
+    val x: A? = A(42)
+    val z = x?.y ?: return
+    x.y
+}
+
+fun getA(): A? = null
+fun useA(a: A): Int = a.hashCode()
+
+fun kt7491_2() {
+    val a = getA()
+    (a?.let { useA(a) } ?: a.<!INAPPLICABLE_CANDIDATE!>y<!> ).toString()
+}
+
+fun String.correct() = true
+
+fun kt8492(s: String?) {
+    if (s?.correct() ?: false) {
+        // To be supported
+        s.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
+
+fun kt11085(prop: String?) {
+    when (prop?.hashCode()) {
+        1 -> prop.length
+    }
+}
+
+class HttpExchange(val code: String)
+
+fun kt11313(arg: HttpExchange?) {
+    when (arg?.code) {
+        "GET" -> handleGet(arg)
+        "POST" -> handlePost(arg)
+    }
+}
+
+fun handleGet(arg: HttpExchange) = arg
+
+fun handlePost(arg: HttpExchange) = arg
+
+class Wrapper {
+    fun unwrap(): String? = "Something not consistent"
+}
+
+fun falsePositive(w: Wrapper) {
+    if (w.unwrap() != null) {
+        // Here we should NOT have smart cast
+        w.unwrap().<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
+
+class Invokable(val x: String) {
+    operator fun invoke() = x
+}
+
+class InvokableProperty(val i: Invokable)
+
+fun checkInvokable(ip: InvokableProperty?) {
+    if (ip?.i() == "Hello") {
+        ip.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/simple.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/simple.fir.kt
new file mode 100644
index 00000000000..31d8b7c2458
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/simple.fir.kt
@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list
+    x?.get(x.size - 1)
+    // but not also here!
+    return x.<!INAPPLICABLE_CANDIDATE!>size<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/simpleNullableReceiver.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/simpleNullableReceiver.fir.kt
new file mode 100644
index 00000000000..a829e21c633
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/simpleNullableReceiver.fir.kt
@@ -0,0 +1,6 @@
+fun Any?.foo(my: My) = my === this
+
+class My(val x: Any)
+
+// my is nullable in brackets because Any?.foo has nullable receiver
+fun foo(my: My?) = my?.x.foo(my)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safecalls/twoArgs.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/safecalls/twoArgs.fir.kt
new file mode 100644
index 00000000000..7017e9b2446
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safecalls/twoArgs.fir.kt
@@ -0,0 +1,6 @@
+fun calc(x: List<String>?): Int {
+    // x should be non-null in arguments list
+    x?.subList(x.size - 1, x.size)
+    // but not also here!
+    return x.<!INAPPLICABLE_CANDIDATE!>size<!>
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/severalSmartCastsOnReified.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/severalSmartCastsOnReified.fir.kt
new file mode 100644
index 00000000000..1b761aebe4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/severalSmartCastsOnReified.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline fun <reified T : CharSequence?> foo(y: Any?) {
+    if (y is T?) {
+        if (y != null) {
+            bar(y)
+        }
+    }
+}
+
+fun bar(x: CharSequence) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/shortIfExprNotNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/shortIfExprNotNull.fir.kt
new file mode 100644
index 00000000000..6e31afb37a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/shortIfExprNotNull.fir.kt
@@ -0,0 +1,9 @@
+fun baz(s: String?): String {
+    val t = if (s != null) s
+    else {
+        val u: String? = null
+        if (u == null) return ""
+        u
+    }
+    return t
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/smartCastAndArgumentApproximation.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/smartCastAndArgumentApproximation.fir.kt
new file mode 100644
index 00000000000..53b68bb314c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/smartCastAndArgumentApproximation.fir.kt
@@ -0,0 +1,8 @@
+/*
+    Here element has type Captured(*) because of resolution for `iterator()` on this.
+    and where we resolve `destination.add(element)` we approximate element to `Any` with smart cast to `R`.
+ */
+inline fun <reified R, C : MutableCollection<in R>> Array<*>.filterIsInstanceTo(destination: C): C {
+    for (element in this) if (element is R) destination.add(element)
+    return destination
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/smartCastOnElvis.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/smartCastOnElvis.fir.kt
new file mode 100644
index 00000000000..2be38a24617
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/smartCastOnElvis.fir.kt
@@ -0,0 +1,15 @@
+fun foo(s: String) = s.length
+
+fun baz(s: String?, r: String?): Int {
+    return foo(r ?: when {
+        s != null -> s
+        else -> ""
+    })
+}
+
+fun bar(s: String?, r: String?): Int {
+    return (r ?: when {
+        s != null -> s
+        else -> ""
+    }).length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/smartCastOnIf.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/smartCastOnIf.fir.kt
new file mode 100644
index 00000000000..341b1fd7e56
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/smartCastOnIf.fir.kt
@@ -0,0 +1,10 @@
+fun baz(s: String?): Int {
+    return if (s == null) {
+        ""
+    }
+    else {
+        val u: String? = null
+        if (u == null) return 0
+        u
+    }.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.fir.kt
new file mode 100644
index 00000000000..9a1e791282b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/smartCastOnWhen.fir.kt
@@ -0,0 +1,20 @@
+// Smart casts on complex expressions
+fun baz(s: String?): Int {
+    if (s == null) return 0
+    return when(s) {
+        "abc" -> s
+        else -> "xyz"
+    }.length
+}
+
+var ss: String? = null
+
+fun bar(): Int {
+    if (ss == null) return 0
+    // ss cannot be smart casted, so an error here
+    return when(ss) {
+        "abc" -> ss
+        else -> "xyz"
+    }.length
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.fir.kt
new file mode 100644
index 00000000000..b30d0201804
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/smartcastOnSameFieldOfDifferentInstances.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+// See KT-27260
+
+class A(val x: String?) {
+    fun foo(other: A) {
+        when {
+            x == null && other.x == null -> "1"
+            x.length > 0 -> "2"
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/thisWithLabel.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/thisWithLabel.fir.kt
new file mode 100644
index 00000000000..618f5b66a69
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/thisWithLabel.fir.kt
@@ -0,0 +1,36 @@
+package foo
+
+class A(val i: Int?) {
+    fun test1() {
+        if (this@A.i != null) {
+            useInt(this.i)
+            useInt(i)
+        }
+    }
+
+    inner class B {
+        fun test2() {
+            if (i != null) {
+                useInt(this@A.i)
+            }
+        }
+    }
+}
+
+fun A.foo() {
+    if (this@foo.i != null) {
+        useInt(this.i)
+        useInt(i)
+    }
+}
+
+fun test3() {
+    useFunction {
+        if(i != null) {
+            useInt(this.i)
+        }
+    }
+}
+
+fun useInt(i: Int) = i
+fun useFunction(f: A.() -> Unit) = f
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/thisWithLabelAsReceiverPart.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/thisWithLabelAsReceiverPart.fir.kt
new file mode 100644
index 00000000000..bdbc0aa44f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/thisWithLabelAsReceiverPart.fir.kt
@@ -0,0 +1,39 @@
+package foo
+
+class C(val i: Int?) {}
+
+class A(val c: C) {
+    fun test1() {
+        if (this@A.c.i != null) {
+            useInt(this.c.i)
+            useInt(c.i)
+        }
+    }
+
+    inner class B {
+        fun test2() {
+            if (c.i != null) {
+                useInt(this@A.c.i)
+            }
+        }
+    }
+}
+
+fun A.foo() {
+    if (this@foo.c.i != null) {
+        useInt(this.c.i)
+        useInt(c.i)
+    }
+}
+
+fun test3() {
+    useFunction {
+        if(c.i != null) {
+            useInt(this.c.i)
+        }
+    }
+}
+
+fun useInt(i: Int) = i
+fun useFunction(f: A.() -> Unit) = f
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/threeImplicitReceivers.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/threeImplicitReceivers.fir.kt
new file mode 100644
index 00000000000..9963912df7c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/threeImplicitReceivers.fir.kt
@@ -0,0 +1,27 @@
+interface IA
+interface IB
+interface IC
+
+object Host : IB
+
+object Prop : IA {
+    val Host.foo: Callee get() = Callee
+}
+
+object Callee
+
+object Invoke : IC {
+    operator fun Callee.invoke() { }
+}
+
+fun test(a: IA, b: IB, c: IC) {
+    with(a) lambdaA@{
+        with(b) lambdaB@{
+            with(c) lambdaC@{
+                if (this@lambdaA is Prop && this@lambdaB is Host && this@lambdaC is Invoke) {
+                    foo()
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/twoImplicitReceivers.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/twoImplicitReceivers.fir.kt
new file mode 100644
index 00000000000..789ca3c61ef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/twoImplicitReceivers.fir.kt
@@ -0,0 +1,18 @@
+interface IA
+interface IB
+
+object A : IA {
+    fun B.foo() {  }
+}
+
+object B : IB
+
+fun test(a: IA, b: IB) {
+    with(a) lambda1@{
+        with(b) lambda2@{
+            if (this@lambda1 is A && this@lambda2 is B) {
+                foo()
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/typeDegradation.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/typeDegradation.fir.kt
new file mode 100644
index 00000000000..8431470f568
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/typeDegradation.fir.kt
@@ -0,0 +1,17 @@
+open class VeryBase
+
+open class Base : VeryBase()
+
+class Derived : Base() {
+    fun original(): VeryBase = this
+}
+
+class Another : Base()
+
+fun foo(d: Derived, a: Another?): Base? {
+    // d is compared with d.original(): VeryBase but should retain its own type
+    if (d.original() != d) return null
+    // ad should be of type Base, not VeryBase
+    val ad = a ?: d
+    return ad
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/typeInComparison.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/typeInComparison.fir.kt
new file mode 100644
index 00000000000..d2481f8146e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/typeInComparison.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+fun foo(): Int {
+    val x: Any? = null
+    val y = 2
+    if (x == y) {
+        return x <!UNRESOLVED_REFERENCE!>+<!> y
+    }
+    return y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/unstableToStable.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/unstableToStable.fir.kt
new file mode 100644
index 00000000000..b229ad774f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/unstableToStable.fir.kt
@@ -0,0 +1,18 @@
+class Foo(var x: Int?) {
+    init {
+        if (x != null) {
+            val y = x
+            // Error: x is not stable, Type(y) = Int?
+            x.hashCode()
+            y.hashCode()
+            if (y == x) {
+                // Still error
+                y.hashCode()
+            }
+            if (x == null && y != x) {
+                // Still error
+                y.hashCode()
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/unstableToStableTypes.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/unstableToStableTypes.fir.kt
new file mode 100644
index 00000000000..75893bf35b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/unstableToStableTypes.fir.kt
@@ -0,0 +1,22 @@
+class Bar {
+    fun bar() {}
+}
+
+class Foo(var x: Any) {
+    init {
+        if (x is Bar) {
+            val y = x
+            // Error: x is not stable, Type(y) = Any
+            x.bar()
+            y.bar()
+            if (y == x) {
+                // Still error
+                y.bar()
+            }
+            if (x !is Bar && y != x) {
+                // Still error
+                y.bar()
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varChangedInInitializer.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varChangedInInitializer.fir.kt
new file mode 100644
index 00000000000..6ca3b6fbe3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varChangedInInitializer.fir.kt
@@ -0,0 +1,7 @@
+class My {
+    init {
+        var y: Int?
+        y = 42
+        y.hashCode()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varChangedInLocalInitializer.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varChangedInLocalInitializer.fir.kt
new file mode 100644
index 00000000000..73cb4c48328
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varChangedInLocalInitializer.fir.kt
@@ -0,0 +1,10 @@
+fun foo() {
+    class My {
+        val x: Int
+        init {
+            var y: Int?
+            y = 42
+            x = y.hashCode()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varInAccessor.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varInAccessor.fir.kt
new file mode 100644
index 00000000000..31b12be35ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varInAccessor.fir.kt
@@ -0,0 +1,17 @@
+var x: Int = 0
+    get() {
+        var y: Int? = null
+        if (y != null) {
+            return y.hashCode()
+        }
+        return field
+    }
+    set(param) {
+        var y: Int? = null
+        if (y != null) {
+            field = y.hashCode()
+        }
+        else {
+            field = param
+        }
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varInInitNoPrimary.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varInInitNoPrimary.fir.kt
new file mode 100644
index 00000000000..e5981c2c85b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varInInitNoPrimary.fir.kt
@@ -0,0 +1,22 @@
+class Your {
+    init {
+        var y: String? = "xyz"
+        if (<!UNRESOLVED_REFERENCE!>y<!> != null) {
+            // Bug that should be fixed
+            // Problem: descriptorToDeclaration cannot get here init block by its descriptor
+            // See PreliminaryDeclarationVisitor.getVisitorByVariable
+            <!UNRESOLVED_REFERENCE!>y<!>.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+        }
+    }
+
+    constructor()
+}
+
+class Normal {
+    init {
+        var y: String? = "xyz"
+        if (y != null) {
+            y.hashCode()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varInInitializer.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varInInitializer.fir.kt
new file mode 100644
index 00000000000..9db530e6266
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varInInitializer.fir.kt
@@ -0,0 +1,12 @@
+class My {
+    val x: Int
+    init {
+        var y: Int? = null
+        if (y != null) {
+            x = y.hashCode()
+        }
+        else {
+            x = 0
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varInSecondaryConstructor.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varInSecondaryConstructor.fir.kt
new file mode 100644
index 00000000000..f9986bbc05c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varInSecondaryConstructor.fir.kt
@@ -0,0 +1,10 @@
+class My(val z: Int) {
+    var x: Int = 0
+    constructor(arg: Int?): this(arg ?: 42) {
+        var y: Int?
+        y = arg
+        if (y != null) {
+            x = y
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varInsideLocalFun.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varInsideLocalFun.fir.kt
new file mode 100644
index 00000000000..907f31dd2a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varInsideLocalFun.fir.kt
@@ -0,0 +1,17 @@
+// Based on KT-8643
+public class MyClass
+{
+    fun main() {
+        var str: String? = null
+
+        if (str != null)
+            callback {
+                // Nodoby writes str, smart cast is possible
+                method1(str)
+            }
+    }
+
+    inline fun callback(foo: () ->Unit) = foo()
+
+    fun method1(str: String) = str
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/accessorAndFunction.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/accessorAndFunction.fir.kt
new file mode 100644
index 00000000000..8d4e295e1ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/accessorAndFunction.fir.kt
@@ -0,0 +1,23 @@
+class My {
+
+    val y: Int 
+        get() {
+            var x: Int?
+            x = 3
+            return x.hashCode()
+        }
+
+    fun test() {
+        var x: Int?
+        x = 2
+        x.hashCode()
+        fun bb() {
+           var x: Any?
+           x = 4
+           x.hashCode()
+        }
+        x = 4
+        // Really smart cast is possible but name shadowing by bb() prevents it
+        x.hashCode()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/assignment.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/assignment.fir.kt
new file mode 100644
index 00000000000..0c157cd4b30
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/assignment.fir.kt
@@ -0,0 +1,10 @@
+fun foo() {
+    var v: Any = 42
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+    v = "abc"
+    v.length
+    v = 42
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+    v = "abc"
+    v.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/assignmentConversion.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/assignmentConversion.fir.kt
new file mode 100644
index 00000000000..d1b35b3fd20
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/assignmentConversion.fir.kt
@@ -0,0 +1,35 @@
+fun foo(x: String) = x
+
+fun test1() {
+    var c: Any? = "XXX"
+    if (c !is String) return
+
+    val newC: String? = "YYY"
+    if (newC != null) {
+        c = newC
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(c)
+}
+
+fun test2() {
+    var c: Any? = "XXX"
+    if (c !is String) return
+
+    val newC: String? = "YYY"
+    if (newC is String) {
+        c = newC
+    }
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(c)
+}
+
+fun test3() {
+    var c: Any? = "XXX"
+    if (c !is String) return
+
+    val newC: String? = "YYY"
+    if (newC == null) return
+    c = newC
+
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(c)
+}
+
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/doWhileWithMiddleBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/doWhileWithMiddleBreak.fir.kt
new file mode 100644
index 00000000000..95a78781df3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/doWhileWithMiddleBreak.fir.kt
@@ -0,0 +1,12 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: Any): Int {
+    var p = pp
+    do {
+        (p as String).length
+        if (p == "abc") break
+        p = 42
+    } while (!x())
+    // Smart cast is NOT possible here
+    return p.<!UNRESOLVED_REFERENCE!>length<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhile.fir.kt
new file mode 100644
index 00000000000..9d04156c7d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhile.fir.kt
@@ -0,0 +1,15 @@
+public fun foo(xx: Any): Int {
+    var x = xx
+    do {
+        var y: Any
+        // After the check, smart cast should work
+        if (x is String) {
+            y = "xyz"
+        } else {
+            y = "abc"
+        }
+        // y!! in both branches
+        y.length
+    } while (!(x is String))
+    return x.<!UNRESOLVED_REFERENCE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhileWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhileWithBreak.fir.kt
new file mode 100644
index 00000000000..d4b85792f05
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/ifElseBlockInsideDoWhileWithBreak.fir.kt
@@ -0,0 +1,16 @@
+public fun foo(xx: Any): Int {
+    var x = xx
+    do {
+        var y: Any
+        // After the check, smart cast should work
+        if (x is String) {
+            break
+        } else {
+            y = "abc"
+        }
+        // y!! in both branches
+        y.length
+    } while (true)
+    // We could have smart cast here but with break it's hard to detect
+    return x.<!UNRESOLVED_REFERENCE!>length<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/ifNullAssignment.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/ifNullAssignment.fir.kt
new file mode 100644
index 00000000000..04df688e9a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/ifNullAssignment.fir.kt
@@ -0,0 +1,73 @@
+// !WITH_NEW_INFERENCE
+// See KT-13468, KT-13765
+
+fun basic(): String {
+    var current: String? = null
+    current = if (current == null) "bar" else current
+    return current
+}
+
+fun foo(flag: Boolean) {
+    var x: String? = null
+
+    if (x == null) {
+        x = if (flag) "34" else "12"
+    }
+
+    x.hashCode()
+}
+
+fun bar(flag: Boolean) {
+    var x: String? = null
+
+    if (x == null) {
+        x = when {
+            flag -> "34"
+            else -> "12"
+        }
+    }
+
+    x.hashCode()
+}
+
+fun baz(flag: Boolean) {
+    var x: String? = null
+
+    if (x == null) {
+        x = if (flag) {
+            "34"
+        } else {
+            "12"
+        }
+    }
+
+    x.hashCode()
+}
+
+fun gav(flag: Boolean, arg: String?) {
+    var x: String? = null
+
+    if (x == null) {
+        x = arg ?: if (flag) {
+            "34"
+        } else {
+            "12"
+        }
+    }
+
+    x.hashCode()
+}
+
+fun gau(flag: Boolean, arg: String?) {
+    var x: String? = null
+
+    if (x == null) {
+        x = if (flag) {
+            arg ?: "34"
+        } else {
+            arg ?: "12"
+        }
+    }
+
+    x.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIs.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIs.fir.kt
new file mode 100644
index 00000000000..f05dbb4bff5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIs.fir.kt
@@ -0,0 +1,9 @@
+public fun bar(s: String) {
+    System.out.println("Length of $s is ${s.length}")
+}
+
+public fun foo() {
+    var s: Any = "not null"
+    if (s is String) 
+        bar(s)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsAnd.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsAnd.fir.kt
new file mode 100644
index 00000000000..dacc37f47a9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsAnd.fir.kt
@@ -0,0 +1,13 @@
+// See KT-5737
+fun get(): Any {
+    return "abc"
+}
+
+fun foo(): Int {
+    var ss: Any = get()
+
+    return if (ss is String && ss.length > 0)
+        1
+    else
+        0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsChanged.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsChanged.fir.kt
new file mode 100644
index 00000000000..5f0fd9dcaf3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/ifVarIsChanged.fir.kt
@@ -0,0 +1,11 @@
+public fun bar(s: String) {
+    System.out.println("Length of $s is ${s.length}")
+}
+
+public fun foo() {
+    var s: Any = "not null"
+    if (s is String) {
+        s = 42
+        bar(s)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/inPropertySam.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/inPropertySam.fir.kt
new file mode 100644
index 00000000000..c25b82199a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/inPropertySam.fir.kt
@@ -0,0 +1,18 @@
+// FILE: My.java
+
+public interface My {
+    String foo(String arg);
+}
+
+// FILE: test.kt
+
+class Your {
+    val x = My() {
+        arg: String? ->
+        var y = arg
+        val z: String
+        if (y != null) z = y
+        else z = "42"
+        z
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/infix.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/infix.fir.kt
new file mode 100644
index 00000000000..5b7085f2d4a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/infix.fir.kt
@@ -0,0 +1,11 @@
+// See KT-774
+fun box() : Int {
+    var a : Any = 1
+    var d = 1
+
+    if (a is Int) {
+        return a + d
+    } else {
+        return 2
+    }
+} 
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/initialization.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/initialization.fir.kt
new file mode 100644
index 00000000000..3c3b0d72337
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/initialization.fir.kt
@@ -0,0 +1,8 @@
+fun foo() {
+    var v: Any = "xyz"
+    // It is possible in principle to provide smart cast here
+    // but now we decide that v is Any
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+    v = 42
+    v.<!UNRESOLVED_REFERENCE!>length<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/kt7599.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/kt7599.fir.kt
new file mode 100644
index 00000000000..7bd807aadbc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/kt7599.fir.kt
@@ -0,0 +1,23 @@
+interface A {
+    fun ok(): Boolean
+}
+
+class B: A {
+    override fun ok(): Boolean { return true }
+}
+
+class C: A {
+    override fun ok(): Boolean { return false }
+}
+
+fun foo(): Boolean {
+    var v: A
+    v = B()
+    // No smart cast needed, but not a problem if ever
+    if (v.ok()) {
+        v = C()
+    }
+    // No smart cast needed, and no smart cast possible!
+    // We cannot choose between B and C
+    return v.ok()
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/lambdaBetweenArguments.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/lambdaBetweenArguments.fir.kt
new file mode 100644
index 00000000000..5c49ba03947
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/lambdaBetweenArguments.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun foo(x: Int, f: () -> Unit, y: Int) {}
+
+fun bar() {
+    var x: Int?
+    x = 4
+    foo(x, { x = null; x.<!UNRESOLVED_REFERENCE!>hashCode<!>() }, x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/property.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/property.fir.kt
new file mode 100644
index 00000000000..85c74542a9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/property.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+class MyClass(var p: String?)
+
+fun bar(s: String): Int {
+    return s.length
+}
+
+fun foo(m: MyClass): Int {
+    m.p = "xyz"
+    return bar(m.p)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/propertyNotNeeded.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/propertyNotNeeded.fir.kt
new file mode 100644
index 00000000000..631449c8f14
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/propertyNotNeeded.fir.kt
@@ -0,0 +1,10 @@
+class MyClass(var p: String?)
+
+fun bar(s: String?): Int {
+    return s?.length ?: -1
+}
+
+fun foo(m: MyClass): Int {
+    m.p = "xyz"
+    return bar(m.p)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtype.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtype.fir.kt
new file mode 100644
index 00000000000..2563e8c449f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtype.fir.kt
@@ -0,0 +1,10 @@
+class MyClass(var p: Any)
+
+fun bar(s: Any): Int {
+    return s.hashCode()
+}
+
+fun foo(m: MyClass): Int {
+    m.p = "xyz"
+    return bar(m.p)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMember.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMember.fir.kt
new file mode 100644
index 00000000000..a47fce835c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMember.fir.kt
@@ -0,0 +1,10 @@
+fun bar(s: Any): Int {
+    return s.hashCode()
+}
+
+class MyClass(var p: Any) {
+    fun foo(): Int {
+        p = "xyz"
+        return bar(p)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMemberCheck.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMemberCheck.fir.kt
new file mode 100644
index 00000000000..1575866e196
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/propertySubtypeInMemberCheck.fir.kt
@@ -0,0 +1,13 @@
+fun bar(s: Any): Int {
+    return s.hashCode()
+}
+
+class MyClass(var p: Any) {
+    fun foo(): Int {
+        p = "xyz"
+        if (p is String) {
+            return bar(p)
+        }
+        return -1
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/varAsUse.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/varAsUse.fir.kt
new file mode 100644
index 00000000000..b86fa4b3d11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/varAsUse.fir.kt
@@ -0,0 +1,9 @@
+fun get(): Any {
+    return ""
+}
+
+fun foo(): Int {
+    var c: Any = get()
+    (c as String).length
+    return c.length // Previous line should make as unnecessary here.
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/varChangedInLoop.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/varChangedInLoop.fir.kt
new file mode 100644
index 00000000000..3146821521a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/varChangedInLoop.fir.kt
@@ -0,0 +1,9 @@
+public fun foo() {
+    var i: Any = 1
+    if (i is Int) {
+        while (i != 10) {
+            i++      // Here smart cast should not be performed due to a successor
+            i = ""
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.fir.kt
new file mode 100644
index 00000000000..1a2eee01965
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/varNotChangedInLoop.fir.kt
@@ -0,0 +1,8 @@
+public fun foo() {
+    var i: Any = 1
+    if (i is Int) {
+        while (i != 10) {
+            i++
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/whileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/whileTrue.fir.kt
new file mode 100644
index 00000000000..3bbf2191c1f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/whileTrue.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: Any): Int {
+    var p = pp
+    while(true) {
+        (p as String).length
+        if (x()) break
+        p = 42
+    }
+    // Smart cast is NOT possible here
+    // (we could provide it but p = 42 makes it difficult to understand)
+    return p.<!UNRESOLVED_REFERENCE!>length<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/variables/whileWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/variables/whileWithBreak.fir.kt
new file mode 100644
index 00000000000..b34bb73ed5e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/variables/whileWithBreak.fir.kt
@@ -0,0 +1,17 @@
+fun String.next(): String {
+    return "abc"
+}
+
+fun list(start: String) {
+    var e: Any? = start
+    if (e==null) return
+    while (e is String) {
+        // Smart cast due to the loop condition
+        if (e.length == 0)
+            break
+        // We still have smart cast here despite of a break
+        e = e.next()
+    }
+    // e can never be null but we do not know it
+    e.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/assignNestedWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/assignNestedWhile.fir.kt
new file mode 100644
index 00000000000..58a8a768091
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/assignNestedWhile.fir.kt
@@ -0,0 +1,28 @@
+class Bar {
+    fun next(): Bar? {
+        if (2 == 4)
+            return this
+        else
+            return null
+    }
+}
+
+fun foo(): Bar {
+    var x: Bar? = Bar()
+    var y: Bar?
+    y = Bar()
+    while (x != null) {
+        // Here call is unsafe because of inner loop
+        y.next()
+        while (y != null) {
+            if (x == y)
+                // x is not null because of outer while
+                return x
+            // y is not null because of inner while
+            y = y.next()
+        }
+        // x is not null because of outer while
+        x = x.next()
+    }
+    return Bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/assignment.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/assignment.fir.kt
new file mode 100644
index 00000000000..3149478be42
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/assignment.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+fun foo() {
+    var v: String? = null
+    v.<!INAPPLICABLE_CANDIDATE!>length<!>
+    v = "abc"
+    v.length
+    v = null
+    v.<!UNRESOLVED_REFERENCE!>length<!>
+    v = "abc"
+    v.<!UNRESOLVED_REFERENCE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializer.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializer.fir.kt
new file mode 100644
index 00000000000..60589b26bb1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializer.fir.kt
@@ -0,0 +1,20 @@
+fun foo(arg: Int?) {
+    val x = arg
+    if (x != null) {
+        arg.hashCode()
+    }
+    val y: Any? = arg
+    if (y != null) {
+        arg.hashCode()
+    }
+    val yy: Any?
+    yy = arg
+    if (yy != null) {
+        arg.hashCode()
+    }
+    var z = arg
+    z = z?.let { 42 }
+    if (z != null) {
+        arg.hashCode()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializerWrong.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializerWrong.fir.kt
new file mode 100644
index 00000000000..7acef4daacf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/boundInitializerWrong.fir.kt
@@ -0,0 +1,46 @@
+// !WITH_NEW_INFERENCE
+// KT-15792 and related
+
+fun foo() {
+    var x: String? = ""
+    val y = x
+    x = null
+    if (y != null) {
+        x.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+    }
+}
+
+fun foo2() {
+    var x: String? = ""
+    val y = x
+    if (y != null) {
+        x.hashCode()
+    }
+}
+
+fun bar(s: String?) {
+    var ss = s
+    val hashCode = ss?.hashCode()
+    ss = null
+    if (hashCode != null) {
+        ss.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+    }
+}
+
+fun bar2(s: String?) {
+    var ss = s
+    val hashCode = ss?.hashCode()
+    if (hashCode != null) {
+        ss.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+    }
+}
+
+class Some(var s: String?)
+
+fun baz(arg: Some?) {
+    val ss = arg?.s
+    if (ss != null) {
+        arg.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+        arg.<!INAPPLICABLE_CANDIDATE!>s<!>.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureModifiedBefore.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureModifiedBefore.fir.kt
new file mode 100644
index 00000000000..5a017f5d5b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureModifiedBefore.fir.kt
@@ -0,0 +1,60 @@
+// !LANGUAGE: +CapturedInClosureSmartCasts
+
+fun run(f: () -> Unit) = f()
+
+fun foo(s: String?) {
+    var x: String? = null
+    if (s != null) {
+        x = s
+    }
+    if (x != null) {
+        run {
+            x.hashCode()
+        }
+    }
+}
+
+fun bar(s: String?) {
+    var x = s
+    if (x != null) {
+        run {
+            x.hashCode()
+        }
+    }
+}
+
+fun baz(s: String?) {
+    var x = s
+    if (x != null) {
+        run {
+            x.hashCode()
+        }
+        run {
+            x.hashCode()
+            x = null
+        }
+    }
+}
+
+fun gaz(s: String?) {
+    var x = s
+    if (x != null) {
+        run {
+            x.hashCode()
+            x = null
+        }
+        run {
+            x.hashCode()
+        }
+    }
+}
+
+fun gav(s: String?) {
+    var x = s
+    if (x != null) {
+        run {
+            x.hashCode()
+        }
+        x = null
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureOff.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureOff.fir.kt
new file mode 100644
index 00000000000..74294986b9a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/capturedInClosureOff.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -CapturedInClosureSmartCasts
+
+fun run(f: () -> Unit) = f()
+
+fun foo(s: String?) {
+    var x: String? = null
+    if (s != null) {
+        x = s
+    }
+    if (x != null) {
+        run {
+            x.hashCode()
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/doWhileWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/doWhileWithBreak.fir.kt
new file mode 100644
index 00000000000..3b1b5feabe3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/doWhileWithBreak.fir.kt
@@ -0,0 +1,21 @@
+data class SomeObject(val n: SomeObject?) {
+    fun doSomething(): Boolean = true
+    fun next(): SomeObject? = n    
+}
+
+
+fun list(start: SomeObject) {
+    var e: SomeObject?
+    e = start
+    do {
+        // In theory smart cast is possible here
+        // But in practice we have a loop with changing e
+        // ?: should we "or" entrance type info with condition type info?
+        if (!e.doSomething())
+            break
+        // Smart cast here is still not possible
+        e = e.next()
+    } while (e != null)
+    // e can be null because of next()
+    e.doSomething()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/doWhileWithMiddleBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/doWhileWithMiddleBreak.fir.kt
new file mode 100644
index 00000000000..2b916f90fb0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/doWhileWithMiddleBreak.fir.kt
@@ -0,0 +1,12 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: String?): Int {
+    var p = pp
+    do {
+        p!!.length
+        if (p == "abc") break
+        p = null
+    } while (!x())
+    // Smart cast is NOT possible here
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEach.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEach.fir.kt
new file mode 100644
index 00000000000..40a920e0373
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEach.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+data class SomeObject(val n: SomeObject?) {
+    fun doSomething() {}
+    fun next(): SomeObject? = n    
+}
+
+
+fun list(start: SomeObject): SomeObject {
+    var e: SomeObject? = start
+    for (i in 0..42) {
+        // Unsafe calls because of nullable e at the beginning
+        e.<!INAPPLICABLE_CANDIDATE!>doSomething<!>()
+        e = e.<!INAPPLICABLE_CANDIDATE!>next<!>()
+    }
+    // Smart cast is not possible here due to next()
+    return e
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEachWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEachWithBreak.fir.kt
new file mode 100644
index 00000000000..dd368ad85c8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEachWithBreak.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+data class SomeObject(val n: SomeObject?) {
+    fun doSomething() {}
+    fun next(): SomeObject? = n    
+}
+
+
+fun list(start: SomeObject): SomeObject {
+    var e: SomeObject? = start
+    for (i in 0..42) {
+        if (e == null)
+            break
+        // Smart casts are possible because of the break before
+        e.doSomething()
+        e = e.next()
+    }
+    return e
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEachWithContinue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEachWithContinue.fir.kt
new file mode 100644
index 00000000000..67fec6fb985
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/forEachWithContinue.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+data class SomeObject(val n: SomeObject?) {
+    fun doSomething() {}
+    fun next(): SomeObject? = n    
+}
+
+
+fun list(start: SomeObject): SomeObject {
+    var e: SomeObject? = start
+    for (i in 0..42) {
+        if (e == null)
+            continue
+        // Smart casts are possible because of the continue before
+        e.doSomething()
+        e = e.next()
+    }
+    return e
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNotNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNotNull.fir.kt
new file mode 100644
index 00000000000..7143c2bbc4b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNotNull.fir.kt
@@ -0,0 +1,9 @@
+public fun fooNotNull(s: String) {
+    System.out.println("Length of $s is ${s.length}")
+}
+
+public fun foo() {
+    var s: String? = "not null"
+    if (s != null)
+        fooNotNull(s)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNotNullAnd.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNotNullAnd.fir.kt
new file mode 100644
index 00000000000..ce7f4a7dcb5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNotNullAnd.fir.kt
@@ -0,0 +1,13 @@
+// See KT-5737
+fun get(): String? {
+    return "abc"
+}
+
+fun foo(): Int {
+    var ss:String? = get()
+
+    return if (ss != null && ss.length > 0)
+        1
+    else
+        0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNullElse.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNullElse.fir.kt
new file mode 100644
index 00000000000..8278d95575c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNullElse.fir.kt
@@ -0,0 +1,12 @@
+public fun fooNotNull(s: String) {
+    System.out.println("Length of $s is ${s.length}")
+}
+
+public fun foo() {
+    var s: String? = "not null"
+    if (s == null) {
+        // Coming soon
+    } else {
+        fooNotNull(s)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNullReturn.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNullReturn.fir.kt
new file mode 100644
index 00000000000..91bc2229578
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/ifVarNullReturn.fir.kt
@@ -0,0 +1,11 @@
+public fun fooNotNull(s: String) {
+    System.out.println("Length of $s is ${s.length}")
+}
+
+public fun foo() {
+    var s: String? = "not null"
+    if (s == null) {
+        return
+    }
+    fooNotNull(s)
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/inference.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/inference.fir.kt
new file mode 100644
index 00000000000..e371be59aee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/inference.fir.kt
@@ -0,0 +1,21 @@
+// See KT-969
+fun f() {
+  var s: String?
+  s = "a"
+  var s1 = "" // String � ?
+  if (s != null) {    // Redundant
+    s1.length
+    // We can do smartcast here and below
+    s1 = s.toString() // return String?
+    s1.length
+    s1 = s
+    s1.length
+    // It's just an assignment without smartcast
+    val s2 = s
+    // But smartcast can be done here
+    s2.length
+    // And also here
+    val s3 = s.toString()
+    s3.length
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/infiniteWhileWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/infiniteWhileWithBreak.fir.kt
new file mode 100644
index 00000000000..f13e2013809
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/infiniteWhileWithBreak.fir.kt
@@ -0,0 +1,20 @@
+data class SomeObject(val n: SomeObject?) {
+    fun doSomething(): Boolean = true
+    fun next(): SomeObject? = n    
+}
+
+
+fun list(start: SomeObject) {
+    var e: SomeObject?
+    e = start
+    // This comparison is senseless
+    while (e != null) {
+        // Smart cast because of the loop condition
+        if (!e.doSomething())
+            break
+        // We still have smart cast here despite of a break
+        e = e.next()
+    } 
+    // e can be null because of next()
+    e.doSomething()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/infix.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/infix.fir.kt
new file mode 100644
index 00000000000..e748ef6da47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/infix.fir.kt
@@ -0,0 +1,11 @@
+// See KT-774
+fun box() : Int {
+    var a : Int? = 1
+    var d = 1
+
+    if (a == null) {
+        return 2
+    } else {
+        return a + d
+    }
+} 
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/initInTryReturnInCatch.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/initInTryReturnInCatch.fir.kt
new file mode 100644
index 00000000000..0788bc8222c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/initInTryReturnInCatch.fir.kt
@@ -0,0 +1,80 @@
+// !WITH_NEW_INFERENCE
+// JAVAC_EXPECTED_FILE
+// See also KT-10735
+fun test() {
+    var a: Int?
+    try {
+        a = 3
+    }
+    catch (e: Exception) {
+        return
+    }
+    a.hashCode() // a is never null here
+}
+class A: Exception()
+class B: Exception()
+fun test2() {
+    var a: Int?
+    try {
+        a = 4
+    }
+    catch (e: A) {
+        return
+    }
+    catch (e: B) {
+        return
+    }
+    a.hashCode() // a is never null here
+}
+fun test3() {
+    var a: Int? = null
+    try {
+        a = 5
+    }
+    catch (e: A) {
+        // do nothing
+    }
+    catch (e: B) {
+        return
+    }
+    a.hashCode() // a is nullable here
+}
+fun test4() {
+    var a: Int? = null
+    try {
+        // do nothing
+    }
+    catch (e: A) {
+        return
+    }
+    catch (e: B) {
+        return
+    }
+    a.<!INAPPLICABLE_CANDIDATE!>hashCode<!>() // a is nullable here
+}
+fun test5() {
+    var a: Int?// = null
+    try {
+        a = 3
+    }
+    catch (e: Exception) {
+        return
+    }
+    finally {
+        a = 5
+    }
+    a.hashCode() // a is never null here
+}
+fun test6() {
+    var a: Int?// = null
+    try {
+        a = 3
+    }
+    catch (e: Exception) {
+        return
+    }
+    finally {
+        a = null
+    }
+    a.<!UNRESOLVED_REFERENCE!>hashCode<!>() // a is null here
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/initialization.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/initialization.fir.kt
new file mode 100644
index 00000000000..6f206aa7d26
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/initialization.fir.kt
@@ -0,0 +1,8 @@
+// !WITH_NEW_INFERENCE
+fun foo() {
+    var v: String? = "xyz"
+    // It is possible in principle to provide smart cast here
+    v.<!INAPPLICABLE_CANDIDATE!>length<!>
+    v = null
+    v.<!UNRESOLVED_REFERENCE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/iterations.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/iterations.fir.kt
new file mode 100644
index 00000000000..4c248fff2d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/iterations.fir.kt
@@ -0,0 +1,14 @@
+data class SomeObject(val n: SomeObject?) {
+    fun doSomething() {}
+    fun next(): SomeObject? = n    
+}
+
+
+fun list(start: SomeObject) {
+    var e: SomeObject? = start
+    while (e != null) {
+        // While condition makes both smart casts possible
+        e.doSomething()
+        e = e.next()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedDoWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedDoWhile.fir.kt
new file mode 100644
index 00000000000..e08d47a1ce4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedDoWhile.fir.kt
@@ -0,0 +1,15 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: String?, rr: String?): Int {
+    var p = pp
+    var r = rr
+    do {
+        do {
+            p!!.length
+        } while (r == null)  
+    } while (!x())
+    // Auto cast possible
+    r.<!INAPPLICABLE_CANDIDATE!>length<!>
+    // Auto cast possible
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedLoops.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedLoops.fir.kt
new file mode 100644
index 00000000000..076b4f3bced
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedLoops.fir.kt
@@ -0,0 +1,19 @@
+fun x(): Boolean { return true }
+
+public fun foo(qq: String?): Int {
+    var q = qq
+    while(true) {
+        q!!.length
+        var r = q
+        do {
+            var p = r
+            do {
+                // p = r, r = q and q is not null
+                p.length
+            } while (!x())
+        } while (r == null) // r = q and q is not null
+        if (!x()) break
+    }
+    // Smart cast is possible
+    return q.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedWhile.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedWhile.fir.kt
new file mode 100644
index 00000000000..828d2c611d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/nestedWhile.fir.kt
@@ -0,0 +1,27 @@
+class Bar {
+    fun next(): Bar? {
+        if (2 == 4)
+            return this
+        else
+            return null
+    }
+}
+
+fun foo(): Bar {
+    var x: Bar? = Bar()
+    var y: Bar? = Bar()
+    while (x != null) {
+        // Here call is unsafe because of initialization and also inner loop
+        y.<!INAPPLICABLE_CANDIDATE!>next<!>()
+        while (y != null) {
+            if (x == y)
+                // x is not null because of outer while
+                return x
+            // y is not null because of inner while
+            y = y.next()
+        }
+        // x is not null because of outer while
+        x = x.next()
+    }
+    return Bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/plusplusMinusminus.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/plusplusMinusminus.fir.kt
new file mode 100644
index 00000000000..dc2a9386d1f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/plusplusMinusminus.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+fun foo(arg: Int?): Int {
+    var i = arg
+    if (i != null && i++ == 5) {
+        return i-- + i
+    }
+    return 0
+}
+
+operator fun Long?.inc() = this?.let { it + 1 }
+
+fun bar(arg: Long?): Long {
+    var i = arg
+    if (i++ == 5L) {
+        return i<!INAPPLICABLE_CANDIDATE!>--<!> + i
+    }
+    if (i++ == 7L) {
+        return i++ <!INAPPLICABLE_CANDIDATE!>+<!> i
+    }
+    return 0L
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNotnullClassIncrement.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNotnullClassIncrement.fir.kt
new file mode 100644
index 00000000000..f596b8eb5ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNotnullClassIncrement.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+class MyClass
+
+operator fun MyClass.inc(): MyClass { return null!! }
+
+public fun box() : MyClass? {
+    var i : MyClass?
+    i = MyClass()
+    // type of j can be inferred as MyClass()
+    var j = i++
+    j.hashCode()
+    return i
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNullableClassIncrement.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNullableClassIncrement.fir.kt
new file mode 100644
index 00000000000..4dcd2429965
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNullableClassIncrement.fir.kt
@@ -0,0 +1,12 @@
+class MyClass
+
+// Correct at compile time but wrong at run-time
+operator fun MyClass?.inc(): MyClass? { return null }
+
+public fun box() : MyClass? {
+    var i : MyClass? 
+    i = MyClass()
+    var j = i++
+    j.hashCode()
+    return i
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNullableIncrement.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNullableIncrement.fir.kt
new file mode 100644
index 00000000000..6dbcb1dd091
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/postfixNullableIncrement.fir.kt
@@ -0,0 +1,8 @@
+operator fun Int?.inc(): Int? { return this }
+
+public fun box(arg: Int?) : Int? {
+    var i : Int? = arg
+    var j = i++
+    j.<!INAPPLICABLE_CANDIDATE!>toInt<!>()
+    return i
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNotnullClassIncrement.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNotnullClassIncrement.fir.kt
new file mode 100644
index 00000000000..b6221b848ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNotnullClassIncrement.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+class MyClass
+
+operator fun MyClass.inc(): MyClass { return null!! }
+
+public fun box() {
+    var i : MyClass?
+    i = MyClass()
+    // Type of j should be inferred as MyClass?
+    var j = ++i
+    // j is null so call is unsafe
+    j.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNullableClassIncrement.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNullableClassIncrement.fir.kt
new file mode 100644
index 00000000000..b4bb5a201ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNullableClassIncrement.fir.kt
@@ -0,0 +1,13 @@
+class MyClass
+
+// Correct at compile time but wrong at run-time
+operator fun MyClass?.inc(): MyClass? { return null }
+
+public fun box() {
+    var i : MyClass? 
+    i = MyClass()
+    // type of j should be MyClass?
+    var j = ++i
+    // j is null so call should be unsafe
+    j.hashCode()
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNullableIncrement.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNullableIncrement.fir.kt
new file mode 100644
index 00000000000..25f99500d48
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/prefixNullableIncrement.fir.kt
@@ -0,0 +1,8 @@
+operator fun Int?.inc(): Int? { return this }
+
+public fun box(arg: Int?) : Int? {
+    var i = arg
+    var j = ++i
+    j.<!INAPPLICABLE_CANDIDATE!>toInt<!>()
+    return ++j
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNotNullInTry.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNotNullInTry.fir.kt
new file mode 100644
index 00000000000..9fd03ec7f93
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNotNullInTry.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +SoundSmartCastsAfterTry
+
+fun bar(arg: Any?) = arg
+
+fun foo() {
+    var s: String?
+    s = null
+    try {
+        s = "Test"
+    } catch (ex: Exception) {}
+    bar(s)
+    if (s != null) { }
+    s.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTry.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTry.fir.kt
new file mode 100644
index 00000000000..71d9ce5881d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTry.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +SoundSmartCastsAfterTry
+
+fun foo() {
+    var s: String?
+    s = "Test"
+    try {
+        s = null
+    } catch (ex: Exception) {}
+    s.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryFinally.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryFinally.fir.kt
new file mode 100644
index 00000000000..fa0415c2556
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryFinally.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: +SoundSmartCastsAfterTry
+
+fun bar() {}
+
+fun foo() {
+    var s: String?
+    s = "Test"
+    try {
+        s = null
+    }
+    catch (ex: Exception) {}
+    finally {
+        bar()
+    }
+    s.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryUnsound.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryUnsound.fir.kt
new file mode 100644
index 00000000000..f6f286f9e36
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setNullInTryUnsound.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: -SoundSmartCastsAfterTry
+
+fun foo() {
+    var s: String?
+    s = "Test"
+    try {
+        s = null
+    } catch (ex: Exception) {}
+    s.<!UNRESOLVED_REFERENCE!>hashCode<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setSameInTry.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setSameInTry.fir.kt
new file mode 100644
index 00000000000..9794a3c7487
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/setSameInTry.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +SoundSmartCastsAfterTry
+
+fun foo() {
+    var s: String?
+    s = "Test"
+    try {
+        s = "Other"
+    } catch (ex: Exception) {}
+    // Problem: here we do not see that 's' is always not-null
+    s.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/toFlexibleType.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/toFlexibleType.fir.kt
new file mode 100644
index 00000000000..97a21e52d45
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/toFlexibleType.fir.kt
@@ -0,0 +1,16 @@
+// FILE: J.java
+
+class J {
+    static String foo() { return "abc"; }
+}
+
+// FILE: test.kt
+
+fun bar() {
+    var v: String?
+    v = J.foo()
+    v.length
+    gav(v)
+}
+
+fun gav(v: String) = v
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessary.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessary.fir.kt
new file mode 100644
index 00000000000..d996a398daa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessary.fir.kt
@@ -0,0 +1,12 @@
+fun String?.foo(): String {
+    return this ?: ""
+}
+
+class MyClass {
+    private var s: String? = null
+
+    fun bar(): String {
+        s = "42"
+        return s.foo()
+    }    
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessaryWithBranch.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessaryWithBranch.fir.kt
new file mode 100644
index 00000000000..5827bba34e2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessaryWithBranch.fir.kt
@@ -0,0 +1,12 @@
+fun String?.foo(): String {
+    return this ?: ""
+}
+
+class MyClass {
+    fun bar(): String {
+        var s: String? = null
+        if (4 < 2)
+            s = "42"
+        return s.foo()
+    }    
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessaryWithMap.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessaryWithMap.fir.kt
new file mode 100644
index 00000000000..5265503fc10
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/unnecessaryWithMap.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+fun create(): Map<String, String> = null!!
+
+operator fun <K, V> Map<K, V>.iterator(): Iterator<Map.Entry<K, V>> = null!!
+
+operator fun <K, V> Map.Entry<K, V>.component1() = key
+
+operator fun <K, V> Map.Entry<K, V>.component2() = value
+
+class MyClass {
+    private var m: Map<String, String>? = null
+    fun foo(): Int {
+        var res = 0
+        m = create()
+        // See KT-7428
+        for ((k, v) in m)
+            res += (k.length + v.length)
+        return res
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInClosure.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInClosure.fir.kt
new file mode 100644
index 00000000000..ad11d03afd1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInClosure.fir.kt
@@ -0,0 +1,17 @@
+public fun foo() {
+    var s: String? = ""
+    fun closure(): Int {
+        if (s == "") {
+            s = null
+            return -1
+        } else if (s == null) {
+            return -2
+        } else {
+            return s.length // Here smartcast is possible, at least in principle
+        }
+    }
+    if (s != null) {
+        System.out.println(closure())
+        System.out.println(s.length)   // Here smartcast is not possible due to a closure predecessor
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInInlineClosure.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInInlineClosure.fir.kt
new file mode 100644
index 00000000000..508d7330612
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInInlineClosure.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// See also KT-7186
+
+fun IntArray.forEachIndexed( op: (i: Int, value: Int) -> Unit) {
+    for (i in 0..this.size)
+        op(i, this[i])
+}
+
+fun max(a: IntArray): Int? {
+    var maxI: Int? = null
+    a.forEachIndexed { i, value ->
+        if (maxI == null || value >= a[maxI])
+            maxI = i
+    }
+    return maxI
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInSafeClosure.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInSafeClosure.fir.kt
new file mode 100644
index 00000000000..9140c8f49c2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCapturedInSafeClosure.fir.kt
@@ -0,0 +1,15 @@
+public fun foo() {
+    var s: String? = ""
+    fun closure(): Int {
+        if (s == null) {
+            return -1
+        } else {
+            return 0
+        }
+    }
+    if (s != null) {
+        System.out.println(closure())
+        // Smart cast is possible, nobody modifies s
+        System.out.println(s.length)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varChangedInLoop.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varChangedInLoop.fir.kt
new file mode 100644
index 00000000000..b0e56a1b8bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varChangedInLoop.fir.kt
@@ -0,0 +1,9 @@
+public fun foo() {
+    var i: Int? = 1
+    if (i != null) {
+        while (i != 10) {
+            i++      // Here smart cast should not be performed due to a successor
+            i = null
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCheck.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCheck.fir.kt
new file mode 100644
index 00000000000..b12378d27a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varCheck.fir.kt
@@ -0,0 +1,9 @@
+fun get(): String? {
+    return ""
+}
+
+fun foo(): Int {
+    var c: String? = get()
+    c!!.length
+    return c.length // Previous line should make !! unnecessary here.
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varIntNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varIntNull.fir.kt
new file mode 100644
index 00000000000..2cb01a3ef43
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varIntNull.fir.kt
@@ -0,0 +1,6 @@
+// !WITH_NEW_INFERENCE
+fun foo(): Int {
+    var i: Int? = 42
+    i = null
+    return i + 1
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNotChangedInLoop.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNotChangedInLoop.fir.kt
new file mode 100644
index 00000000000..b36be19bf86
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNotChangedInLoop.fir.kt
@@ -0,0 +1,8 @@
+public fun foo() {
+    var i: Int? = 1
+    if (i != null) {
+        while (i != 10) {
+            i++
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNull.fir.kt
new file mode 100644
index 00000000000..4fbd84ed5f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/varNull.fir.kt
@@ -0,0 +1,6 @@
+// !WITH_NEW_INFERENCE
+fun foo(): Int {
+    var s: String? = "abc"
+    s = null
+    return s.<!UNRESOLVED_REFERENCE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrue.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrue.fir.kt
new file mode 100644
index 00000000000..964baa75abc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrue.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: String?): Int {
+    var p = pp
+    while(true) {
+        p!!.length
+        if (x()) break
+        p = null
+    }
+    // Smart cast is NOT possible here
+    // (we could provide it but p = null makes it much harder)
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrueWithBracketSet.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrueWithBracketSet.fir.kt
new file mode 100644
index 00000000000..2fe1af49ac4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrueWithBracketSet.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: String?): Int {
+    var p = pp
+    while(true) {
+        p!!.length
+        if (x()) break
+        (((p))) = null
+    }
+    // Smart cast is NOT possible here
+    // (we could provide it but p = null makes it much harder)
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrueWithBrackets.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrueWithBrackets.fir.kt
new file mode 100644
index 00000000000..2c3a154ffdf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileTrueWithBrackets.fir.kt
@@ -0,0 +1,13 @@
+fun x(): Boolean { return true }
+
+public fun foo(pp: String?): Int {
+    var p = pp
+    while(true) {
+        p!!.length
+        if (x()) break
+        (p) = null
+    }
+    // Smart cast is NOT possible here
+    // (we could provide it but p = null makes it much harder)
+    return p.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileWithBreak.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileWithBreak.fir.kt
new file mode 100644
index 00000000000..0d5e3c38d9f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/varnotnull/whileWithBreak.fir.kt
@@ -0,0 +1,17 @@
+data class SomeObject(val n: SomeObject?) {
+    fun doSomething(): Boolean = true
+    fun next(): SomeObject? = n    
+}
+
+fun list(start: SomeObject) {
+    var e: SomeObject? = start
+    while (e != null) {
+        // Smart cast due to the loop condition
+        if (!e.doSomething())
+            break
+        // We still have smart cast here despite of a break
+        e = e.next()
+    }
+    // e can be null because of next()
+    e.doSomething()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/whenExprNonNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/whenExprNonNull.fir.kt
new file mode 100644
index 00000000000..8f9a8e31649
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/whenExprNonNull.fir.kt
@@ -0,0 +1,18 @@
+fun baz(s: String?): String {
+    if (s == null) return ""
+    // if explicit type String is given for t, problem disappears
+    val t = when(s) {
+        // !! is detected as unnecessary here
+        "abc" -> s
+        else -> "xyz"
+    }
+    return t
+}
+
+fun foo(s: String?): String {
+    val t = when {
+        s != null -> s
+        else -> ""
+    }
+    return t
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/whenIfExprNonNull.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/whenIfExprNonNull.fir.kt
new file mode 100644
index 00000000000..36f60e69c1e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/whenIfExprNonNull.fir.kt
@@ -0,0 +1,13 @@
+fun baz(s: String?, u: String?): String {
+    val t = when(s) {
+        is String -> {
+            if (u == null) return s
+            u
+        }
+        else -> {
+            if (u == null) return ""
+            u
+        }
+    }
+    return t
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossible.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossible.fir.kt
new file mode 100644
index 00000000000..a679b102d71
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossible.fir.kt
@@ -0,0 +1,10 @@
+// See KT-10061
+
+class My {
+    val x: Int? get() = 42
+}
+
+fun foo(my: My) {
+    my.x!!
+    when (my.x) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossibleJava.fir.kt b/compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossibleJava.fir.kt
new file mode 100644
index 00000000000..955e071a1d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/whenSubjectImpossibleJava.fir.kt
@@ -0,0 +1,11 @@
+// See KT-10061
+// FILE: My.java
+public class My {
+    String getSomething() { return "xyz"; }
+}
+
+// FILE: My.kt
+fun foo(my: My) {
+    my.something!!
+    when (my.something) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/annotations.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/annotations.fir.kt
new file mode 100644
index 00000000000..a5c28aa873c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/annotations.fir.kt
@@ -0,0 +1,11 @@
+// !API_VERSION: 1.0
+
+@SinceKotlin("1.1")
+annotation class Anno1(val s: String)
+
+annotation class Anno2 @SinceKotlin("1.1") constructor()
+
+
+@Anno1("")
+@Anno2
+fun t1() {}
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/classesAndConstructors.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/classesAndConstructors.fir.kt
new file mode 100644
index 00000000000..64b5a3678bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/classesAndConstructors.fir.kt
@@ -0,0 +1,23 @@
+// !API_VERSION: 1.0
+
+@SinceKotlin("1.1")
+open class Foo
+
+class Bar @SinceKotlin("1.1") constructor()
+
+@SinceKotlin("1.0")
+class Baz @SinceKotlin("1.1") constructor()
+
+@SinceKotlin("1.1")
+class Quux @SinceKotlin("1.0") constructor()
+
+fun t1(): Foo = Foo()
+
+// TODO: do not report API_NOT_AVAILABLE twice
+fun t2() = object : Foo() {}
+
+fun t3(): Bar? = Bar()
+
+fun t4(): Baz = Baz()
+
+fun t5(): Quux = Quux()
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/overriddenMembers.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/overriddenMembers.fir.kt
new file mode 100644
index 00000000000..a7a245388c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/overriddenMembers.fir.kt
@@ -0,0 +1,34 @@
+// !API_VERSION: 1.0
+// FILE: J.java
+
+public interface J {
+    void foo();
+}
+
+// FILE: test.kt
+
+interface I10 {
+    @SinceKotlin("1.0")
+    fun foo()
+}
+
+interface I11 {
+    @SinceKotlin("1.1")
+    fun foo()
+}
+
+fun f1(x: I10) = x.foo()
+fun f2(x: I11) = x.foo()
+fun f3(x: J) = x.foo()
+
+interface BothI1 : I10, I11
+fun f4(x: BothI1) = x.foo()
+
+interface BothI2 : I11, I10
+fun f5(x: BothI2) = x.foo()
+
+interface JAndI10 : J, I10
+fun f6(x: JAndI10) = x.foo()
+
+interface JAndI11 : J, I11
+fun f7(x: JAndI11) = x.foo()
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/propertyAccessors.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/propertyAccessors.fir.kt
new file mode 100644
index 00000000000..fa394d768ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/propertyAccessors.fir.kt
@@ -0,0 +1,48 @@
+// !API_VERSION: 1.0
+
+val v1: String
+    @SinceKotlin("1.1")
+    get() = ""
+
+@SinceKotlin("1.1")
+val v2 = ""
+
+var v3: String
+    @SinceKotlin("1.1")
+    get() = ""
+    set(value) {}
+
+var v4: String
+    get() = ""
+    @SinceKotlin("1.1")
+    set(value) {}
+
+var v5: String
+    @SinceKotlin("1.1")
+    get() = ""
+    @SinceKotlin("1.1")
+    set(value) {}
+
+@SinceKotlin("1.1")
+var v6: String
+    get() = ""
+    set(value) {}
+
+@SinceKotlin("1.0")
+val v7: String
+    @SinceKotlin("1.1")
+    get() = ""
+
+fun test() {
+    v1
+    v2
+    v3
+    v3 = ""
+    v4
+    v4 = ""
+    v5
+    v5 = ""
+    v6
+    v6 = ""
+    v7
+}
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/simpleMembers.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/simpleMembers.fir.kt
new file mode 100644
index 00000000000..69a4086b5a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/simpleMembers.fir.kt
@@ -0,0 +1,19 @@
+// !API_VERSION: 1.0
+
+@SinceKotlin("1.1")
+fun f() {}
+
+@SinceKotlin("1.1")
+var p = Unit
+
+@SinceKotlin("1.1.2")
+fun z() {}
+
+
+fun t1() = f()
+
+fun t2() = p
+
+fun t3() { p = Unit }
+
+fun t4() { z() }
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/sinceOldVersionIsOK.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/sinceOldVersionIsOK.fir.kt
new file mode 100644
index 00000000000..6d35fbdbbb6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/sinceOldVersionIsOK.fir.kt
@@ -0,0 +1,18 @@
+// !API_VERSION: 1.1
+
+@SinceKotlin("0.9")
+fun ok1() {}
+
+@SinceKotlin("1.0")
+fun ok2() {}
+
+@SinceKotlin("1.1")
+fun ok3() {}
+
+@SinceKotlin("0.9.9")
+fun ok4() {}
+
+fun t1() = ok1()
+fun t2() = ok2()
+fun t3() = ok3()
+fun t4() = ok4()
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsCompanionObjects.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsCompanionObjects.fir.kt
new file mode 100644
index 00000000000..402e126017c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsCompanionObjects.fir.kt
@@ -0,0 +1,15 @@
+// !API_VERSION: 1.0
+
+class C {
+    @SinceKotlin("1.1")
+    companion object {
+        val x = 42
+    }
+}
+
+typealias CA = C
+
+val test1 = CA
+val test2 = CA.<!UNRESOLVED_REFERENCE!>Companion<!>
+val test3 = CA.<!UNRESOLVED_REFERENCE!>x<!>
+val test4 = CA.<!UNRESOLVED_REFERENCE!>Companion<!>.<!UNRESOLVED_REFERENCE!>x<!>
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsConstructors.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsConstructors.fir.kt
new file mode 100644
index 00000000000..9eb127a0378
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsConstructors.fir.kt
@@ -0,0 +1,20 @@
+// !API_VERSION: 1.0
+
+@SinceKotlin("1.1")
+open class C1
+
+typealias C1_Alias = C1
+
+open class C2(val x: Int) {
+    @SinceKotlin("1.1")
+    constructor() : this(0)
+}
+
+typealias C2_Alias = C2
+
+val test1 = C1_Alias()
+val test2 = C2_Alias()
+
+class Test3 : C1_Alias()
+
+class Test4 : C2_Alias()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsObjects.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsObjects.fir.kt
new file mode 100644
index 00000000000..2b1f84d53ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsObjects.fir.kt
@@ -0,0 +1,11 @@
+// !API_VERSION: 1.0
+
+@SinceKotlin("1.1")
+object Since_1_1 {
+    val x = 42
+}
+
+typealias Since_1_1_Alias = Since_1_1
+
+val test1 = Since_1_1_Alias
+val test2 = Since_1_1_Alias.<!UNRESOLVED_REFERENCE!>x<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsTypes.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsTypes.fir.kt
new file mode 100644
index 00000000000..ae3d59b28bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesAsTypes.fir.kt
@@ -0,0 +1,21 @@
+// !API_VERSION: 1.0
+
+@SinceKotlin("1.1")
+class Since_1_1
+
+class C
+
+typealias Since_1_1_Alias = Since_1_1
+
+typealias L = List<Since_1_1>
+
+@SinceKotlin("1.1")
+typealias C_1_1_Alias = C
+
+fun test1(x: Since_1_1_Alias) = x
+
+fun test2(x: C_1_1_Alias) = x
+
+fun test3(x: List<C_1_1_Alias>) = x
+
+fun test4(x: L) = x
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesOnImport.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesOnImport.fir.kt
new file mode 100644
index 00000000000..9c530c9909f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/apiVersion/typealiasesOnImport.fir.kt
@@ -0,0 +1,18 @@
+// !API_VERSION: 1.0
+
+// FILE: a.kt
+package a
+
+@SinceKotlin("1.1")
+class Since_1_1
+
+typealias Since_1_1_Alias = Since_1_1
+
+@SinceKotlin("1.1")
+typealias Alias_1_1 = String
+
+// FILE: b.kt
+package b
+
+import a.Since_1_1_Alias
+import a.Alias_1_1
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/inlineFunctionAlways.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/inlineFunctionAlways.fir.kt
new file mode 100644
index 00000000000..c6d1216532e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/inlineFunctionAlways.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -NOTHING_TO_INLINE
+// !LANGUAGE: -InlineProperties
+
+inline fun String.test() {
+}
+
+inline fun test() {
+}
+
+class A {
+    inline fun String.test() {
+    }
+
+    inline fun test() {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noBigFunctionTypes.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noBigFunctionTypes.fir.kt
new file mode 100644
index 00000000000..2f55c492f1c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noBigFunctionTypes.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: -FunctionTypesWithBigArity
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A
+
+fun foo(
+    p00: A, p01: A, p02: A, p03: A, p04: A, p05: A, p06: A, p07: A, p08: A, p09: A,
+    p10: A, p11: A, p12: A, p13: A, p14: A, p15: A, p16: A, p17: A, p18: A, p19: A,
+    p20: A, p21: A, p22: A, p23: A, p24: A, p25: A, p26: A, p27: A, p28: A, p29: A
+) {}
+
+fun bar(x: Any) {}
+
+fun test(
+    w: (A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A, A) -> Unit,
+    vararg x: Function30<*, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, *, Unit>
+) {
+    bar(::foo)
+    bar(x)
+}
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/boundCallableReference.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/boundCallableReference.fir.kt
new file mode 100644
index 00000000000..fb99289ec37
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/boundCallableReference.fir.kt
@@ -0,0 +1,25 @@
+// !LANGUAGE: -BoundCallableReferences
+
+class C { companion object }
+val ok1 = C::hashCode
+val fail1 = C.Companion::hashCode
+
+object O {
+    class Y {
+        companion object
+    }
+}
+val fail2 = O::hashCode
+val ok2 = O::Y
+val ok3 = O.Y::hashCode
+
+enum class E {
+    Entry
+}
+val ok4 = E.Entry::hashCode
+
+fun hashCode() {}
+
+val fail3 = ""::hashCode
+val fail4 = (C)::hashCode
+val fail5 = (C.Companion)::hashCode
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/boundClassLiteral.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/boundClassLiteral.fir.kt
new file mode 100644
index 00000000000..12d5a76b87e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/boundClassLiteral.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: -BoundCallableReferences
+
+class C { companion object }
+val ok1 = C::class
+val ok2 = C.Companion::class
+
+object O
+val ok3 = O::class
+
+enum class E {
+    Entry
+}
+val ok4 = E.Entry::class
+
+val fail1 = ""::class
+val fail2 = String?::class
+val fail3 = (C)::class
+val fail4 = (C.Companion)::class
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/qualifiedJavaClassLiteralInKClassExtension.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/qualifiedJavaClassLiteralInKClassExtension.fir.kt
new file mode 100644
index 00000000000..7655e84d0b8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/qualifiedJavaClassLiteralInKClassExtension.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: -BoundCallableReferences
+// !DIAGNOSTICS: -UNCHECKED_CAST
+
+import kotlin.reflect.KClass
+
+val <T : Any> KClass<T>.java: Class<T> get() = null!!
+
+val <T : Any> KClass<T>.javaObjectType: Class<T>
+    get() {
+        return java.<!UNRESOLVED_REFERENCE!>lang<!>.<!UNRESOLVED_REFERENCE!>Class<!>::class.<!INAPPLICABLE_CANDIDATE!>java<!> as Class<T>
+    }
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/qualifiedJavaClassReferenceInKClassExtension.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/qualifiedJavaClassReferenceInKClassExtension.fir.kt
new file mode 100644
index 00000000000..13462c5f330
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noBoundCallableReferences/qualifiedJavaClassReferenceInKClassExtension.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: -BoundCallableReferences
+
+import kotlin.reflect.KClass
+
+val <T : Any> KClass<T>.java: Class<T> get() = null!!
+
+val <T : Any> KClass<T>.foo: Any?
+    get() {
+        return java.<!UNRESOLVED_REFERENCE!>lang<!>.<!UNRESOLVED_REFERENCE!>Integer<!>::hashCode
+    }
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noCallableReferencesWithEmptyLHS.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noCallableReferencesWithEmptyLHS.fir.kt
new file mode 100644
index 00000000000..afe35203131
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noCallableReferencesWithEmptyLHS.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: -CallableReferencesToClassMembersWithEmptyLHS
+
+class A {
+    fun memberFunction() {}
+    val memberProperty: Int get() = 42
+
+    fun test() {
+        (::memberFunction)()
+        (::extensionFunction)()
+        (::memberProperty)()
+        (::extensionProperty)()
+    }
+
+    inner class B {
+        fun memberFunction() { }
+        val memberProperty: Int get() = 43
+
+        fun test() {
+            (::memberFunction)()
+            (::extensionFunction)()
+            (::memberProperty)()
+            (::extensionProperty)()
+        }
+    }
+}
+
+fun A.extensionFunction() {}
+val A.extensionProperty: Int get() = 44
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noDataClassInheritance.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noDataClassInheritance.fir.kt
new file mode 100644
index 00000000000..4a83ee84a13
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noDataClassInheritance.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: -DataClassInheritance
+
+interface Allowed
+
+open class NotAllowed
+
+abstract data class Base(val x: Int)
+
+class Derived: Base(42)
+
+data class Nasty(val z: Int, val y: Int): Base(z)
+
+data class Complex(val y: Int): Allowed, NotAllowed()
+
+
+
+interface AbstractEqualsHashCodeToString {
+    override fun equals(other: Any?): Boolean
+    override fun hashCode(): Int
+    override fun toString(): String
+}
+
+data class ImplInterface(val s: String) : AbstractEqualsHashCodeToString
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noInlineProperty.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noInlineProperty.fir.kt
new file mode 100644
index 00000000000..417acde382f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noInlineProperty.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: -InlineProperties
+var value: Int = 0
+
+inline var z: Int
+    get() = ++value
+    set(p: Int) { value = p }
+
+
+var z2: Int
+    inline get() = ++value
+    inline set(p: Int) { value = p }
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noLocalDelegatedProperty.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noLocalDelegatedProperty.fir.kt
new file mode 100644
index 00000000000..9426f1ed15a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noLocalDelegatedProperty.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: -LocalDelegatedProperties
+import kotlin.reflect.KProperty
+
+class Delegate {
+    operator fun getValue(t: Any?, p: KProperty<*>): Int = 1
+}
+
+fun foo(): Int {
+    val prop: Int by Delegate()
+
+    val prop2: Int by 123
+
+    val obj = object {
+        fun v(): Int {
+            val prop3: Int by Delegate()
+            return prop3
+        }
+    }
+
+    return prop + prop2 + obj.v()
+}
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noMultiplatformProjects.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noMultiplatformProjects.fir.kt
new file mode 100644
index 00000000000..3032aaa5e43
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noMultiplatformProjects.fir.kt
@@ -0,0 +1,7 @@
+expect fun foo1()
+expect val bar1 = 42
+expect class Baz1
+
+actual fun foo2() = 42
+actual val bar2: Int
+actual interface Baz2
diff --git a/compiler/testData/diagnostics/tests/sourceCompatibility/noTopLevelSealedInheritance.fir.kt b/compiler/testData/diagnostics/tests/sourceCompatibility/noTopLevelSealedInheritance.fir.kt
new file mode 100644
index 00000000000..1e1cc9ad267
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/sourceCompatibility/noTopLevelSealedInheritance.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: -TopLevelSealedInheritance
+
+sealed class Base
+
+class Derived : Base()
diff --git a/compiler/testData/diagnostics/tests/substitutions/kt1558-short.fir.kt b/compiler/testData/diagnostics/tests/substitutions/kt1558-short.fir.kt
new file mode 100644
index 00000000000..daee244f735
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/substitutions/kt1558-short.fir.kt
@@ -0,0 +1,5 @@
+fun <E> List<*>.toArray(ar: Array<E>): Array<E> = ar
+
+fun testArrays(ci : List<Int>) {
+    ci.toArray<Int>(<!UNRESOLVED_REFERENCE!>x<!>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/substitutions/kt4887.fir.kt b/compiler/testData/diagnostics/tests/substitutions/kt4887.fir.kt
new file mode 100644
index 00000000000..777fa655cc6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/substitutions/kt4887.fir.kt
@@ -0,0 +1,8 @@
+package h
+
+public class MyClass<S, T>(param: MyClass<S, T>) {
+    fun test() {
+        val result: MyClass<Any, Any>? = null
+        MyClass<S, Any>(result as MyClass<S, Any>)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/substitutions/starProjections.fir.kt b/compiler/testData/diagnostics/tests/substitutions/starProjections.fir.kt
new file mode 100644
index 00000000000..c3acdadbf5f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/substitutions/starProjections.fir.kt
@@ -0,0 +1,25 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+interface A<R, T: A<R, T>> {
+    fun r(): R
+    fun t(): T
+}
+
+fun testA(a: A<*, *>) {
+    a.r().checkType { _<Any?>() }
+    a.t().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><A<*, *>>() }
+}
+
+interface B<R, T: B<List<R>, T>> {
+    fun r(): R
+    fun t(): T
+}
+
+fun testB(b: B<*, *>) {
+    b.r().checkType { _<Any?>() }
+    b.t().checkType { <!INAPPLICABLE_CANDIDATE!>_<!><B<List<*>, *>>() }
+
+    b.t().r().size
+}
+
diff --git a/compiler/testData/diagnostics/tests/substitutions/upperBoundsSubstitutionForOverloadResolutionWithAmbiguity.fir.kt b/compiler/testData/diagnostics/tests/substitutions/upperBoundsSubstitutionForOverloadResolutionWithAmbiguity.fir.kt
new file mode 100644
index 00000000000..fb10e0b812c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/substitutions/upperBoundsSubstitutionForOverloadResolutionWithAmbiguity.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// FILE: foo.kt
+package foo
+
+fun <T> f(l: List<T>) {}
+
+// FILE: bar.kt
+package bar
+
+fun <T> f(l: List<T>) {}
+
+// FILE: main.kt
+
+import foo.*
+import bar.*
+
+fun <T> test(l: List<T>) {
+    <!AMBIGUITY!>f<!>(l)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/substitutions/upperBoundsSubstitutionForOverloadResolutionWithErrorTypes.fir.kt b/compiler/testData/diagnostics/tests/substitutions/upperBoundsSubstitutionForOverloadResolutionWithErrorTypes.fir.kt
new file mode 100644
index 00000000000..89c3f648ab8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/substitutions/upperBoundsSubstitutionForOverloadResolutionWithErrorTypes.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -CONFLICTING_JVM_DECLARATIONS -UNUSED_PARAMETER
+fun <T> f1(l: List1<T>): T {throw Exception()} // ERROR type here
+fun <T> f1(l: List2<T>): T {throw Exception()} // ERROR type here
+fun <T> f1(c: Collection<T>): T{throw Exception()}
+
+fun <T> test(l: List<T>) {
+    f1(l)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/extFunctionTypeAsSuperType.fir.kt b/compiler/testData/diagnostics/tests/subtyping/extFunctionTypeAsSuperType.fir.kt
new file mode 100644
index 00000000000..9a3efab4a69
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/extFunctionTypeAsSuperType.fir.kt
@@ -0,0 +1,24 @@
+class A : Double.() -> Unit {
+    override fun invoke(p1: Double) {}
+}
+
+class B : Int.(Double) -> Unit {
+    override fun invoke(p1: Int, p2: Double) {}
+}
+
+open class C {}
+
+abstract class A0 : C.() -> Int
+abstract class A1 : C.(Int) -> Int
+abstract class A2 : C.(Int, String) -> Int
+
+open class D<T> {}
+
+abstract class B0<T> : D<T>.() -> Int
+abstract class B1<T> : D<T>.(C) -> Int
+abstract class B2<T> : D<T>.(T, C) -> T
+
+interface E<T> {}
+
+abstract class C0: C(), Int.() -> Double
+abstract class C1<T>: C(), E<T>, Int.(C) -> Double
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/findClosestCorrespondingSupertype.fir.kt b/compiler/testData/diagnostics/tests/subtyping/findClosestCorrespondingSupertype.fir.kt
new file mode 100644
index 00000000000..30bd7887a92
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/findClosestCorrespondingSupertype.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+interface X<T>
+interface A: X<String>
+interface B : A, X<Int>
+
+fun foo(x: B) {
+    // Checks that when checking subtypes we search closes corresponding constructor (e.g. with BFS)
+    val y: X<Int> = x
+}
diff --git a/compiler/testData/diagnostics/tests/subtyping/functionTypeAsSuperType.fir.kt b/compiler/testData/diagnostics/tests/subtyping/functionTypeAsSuperType.fir.kt
new file mode 100644
index 00000000000..c52250c1c84
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/functionTypeAsSuperType.fir.kt
@@ -0,0 +1,45 @@
+class A : () -> Unit {
+    override fun invoke() {}
+}
+
+class AA : Function0<Unit> {
+    override fun invoke() {}
+}
+
+class B : (Double) -> Unit {
+    override fun invoke(p1: Double) {}
+}
+
+class BB : Function1<Double, Unit> {
+    override fun invoke(p1: Double) {}
+}
+
+open class C {}
+
+abstract class A0 : (C) -> Int
+abstract class A1 : Function1<C, Int>
+
+abstract class A2 : (C, Int) -> Int
+abstract class A3 : Function2<C, Int, Int>
+
+abstract class A4 : (Int, C, String) -> Int
+abstract class A5 : Function3<Int, C, String, Int>
+
+open class D<T> {}
+
+abstract class B0<T> : (D<T>) -> Int
+abstract class B1<T> : Function1<D<T>, Int>
+
+abstract class B2<T> : (D<T>, C) -> Int
+abstract class B3<T> : Function2<D<T>, C, Int>
+
+abstract class B4<T> : (D<T>, C) -> T
+abstract class B5<T> : Function2<D<T>, C, T>
+
+interface E<T> {}
+
+abstract class C0: C(), (Int) -> Double
+abstract class C1: C(), Function1<Int, Double>
+
+abstract class C2<T>: C(), E<T>, (Int, C) -> Double
+abstract class C3<T>: C(), E<T>, Function2<Int, C, Double>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/invariantArgumentForTypeParameterWithMultipleBounds.fir.kt b/compiler/testData/diagnostics/tests/subtyping/invariantArgumentForTypeParameterWithMultipleBounds.fir.kt
new file mode 100644
index 00000000000..1f48345b327
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/invariantArgumentForTypeParameterWithMultipleBounds.fir.kt
@@ -0,0 +1,18 @@
+import java.io.Serializable
+
+class A<T> where T : Cloneable, T : Serializable
+
+interface CS1 : Cloneable, Serializable
+interface CS2 : CS1
+
+interface I1 {
+    fun foo(): A<in CS2>
+}
+
+interface I2 : I1 {
+    override fun foo(): A<CS1>
+}
+
+interface I3 : I1 {
+    override fun foo(): A<in CS1>
+}
diff --git a/compiler/testData/diagnostics/tests/subtyping/javaAndKotlinSuperType.fir.kt b/compiler/testData/diagnostics/tests/subtyping/javaAndKotlinSuperType.fir.kt
new file mode 100644
index 00000000000..8f0cd59d18a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/javaAndKotlinSuperType.fir.kt
@@ -0,0 +1,42 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: A.java
+public interface A<T> {
+}
+
+// FILE: B.java
+public class B implements A<String> {
+}
+
+// FILE: 1.kt
+class C: B()
+
+class D: B(), A<String>
+class E: B(), A<String?>
+
+fun eatAString(a: A<String>) {}
+fun eatAStringN(a: A<String?>) {}
+
+fun test(b: B, c: C, d: D, e: E) {
+    eatAString(b)
+    eatAString(c)
+    eatAString(d)
+    eatAString(e)
+
+    <!INAPPLICABLE_CANDIDATE!>eatAStringN<!>(b)
+    <!INAPPLICABLE_CANDIDATE!>eatAStringN<!>(c)
+    <!INAPPLICABLE_CANDIDATE!>eatAStringN<!>(d)
+    <!INAPPLICABLE_CANDIDATE!>eatAStringN<!>(e)
+}
+
+// FILE: 3.kt
+
+interface X : A<String>
+interface Y: X
+interface Z: X
+
+class W: B(), Z
+
+fun test2(w: W) {
+    eatAString(w)
+    <!INAPPLICABLE_CANDIDATE!>eatAStringN<!>(w)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/kt-1457.fir.kt b/compiler/testData/diagnostics/tests/subtyping/kt-1457.fir.kt
new file mode 100644
index 00000000000..7c0768cc801
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/kt-1457.fir.kt
@@ -0,0 +1,12 @@
+// !CHECK_TYPE
+// JAVAC_EXPECTED_FILE
+
+import java.util.ArrayList
+
+class Pair<A, B>(val a: A, val b: B)
+
+class MyListOfPairs<T> : ArrayList<Pair<T, T>>() { }
+
+fun test() {
+    checkSubtype<ArrayList<Pair<Int, Int>>>(MyListOfPairs<Int>())
+}
diff --git a/compiler/testData/diagnostics/tests/subtyping/kt2069.fir.kt b/compiler/testData/diagnostics/tests/subtyping/kt2069.fir.kt
new file mode 100644
index 00000000000..c2c70d7bcb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/kt2069.fir.kt
@@ -0,0 +1,14 @@
+//KT-2069 Cannot call super method when superclass has type parameters
+package kt2069
+
+interface T1 {
+    fun foo() {}
+}
+
+class T : T1 {
+    fun bar() {
+        super<T1>.foo()
+    }
+
+    companion object {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/kt2744.fir.kt b/compiler/testData/diagnostics/tests/subtyping/kt2744.fir.kt
new file mode 100644
index 00000000000..eb1496c3f65
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/kt2744.fir.kt
@@ -0,0 +1,3 @@
+class X : S
+
+fun f(l: List<X>) {}
diff --git a/compiler/testData/diagnostics/tests/subtyping/kt304.fir.kt b/compiler/testData/diagnostics/tests/subtyping/kt304.fir.kt
new file mode 100644
index 00000000000..aab7fe69d26
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/kt304.fir.kt
@@ -0,0 +1,7 @@
+//KT-304: Resolve supertype reference to class anyway
+
+open class Foo() : Bar() {
+}
+
+open class Bar<T>() {
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/kt3159.fir.kt b/compiler/testData/diagnostics/tests/subtyping/kt3159.fir.kt
new file mode 100644
index 00000000000..2d736b76b07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/kt3159.fir.kt
@@ -0,0 +1,9 @@
+interface Super {
+    var v: CharSequence
+    val v2: CharSequence
+}
+
+class Sub: Super {
+    override var v: String = "fail"
+    override val v2: String = "ok"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/localAnonymousObjects.fir.kt b/compiler/testData/diagnostics/tests/subtyping/localAnonymousObjects.fir.kt
new file mode 100644
index 00000000000..c730c51833c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/localAnonymousObjects.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE
+fun test() {
+    var x = object {}
+    x = object {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/localClasses.fir.kt b/compiler/testData/diagnostics/tests/subtyping/localClasses.fir.kt
new file mode 100644
index 00000000000..9306dd94882
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/localClasses.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER
+
+package p
+
+private fun foo(a: Int) = run {
+    class A
+    A()
+}
+
+private fun foo() = run {
+    class A
+    A()
+}
+
+fun test() {
+    var x = foo(1)
+    x = foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/memberAnonymousObjects.fir.kt b/compiler/testData/diagnostics/tests/subtyping/memberAnonymousObjects.fir.kt
new file mode 100644
index 00000000000..f13a0613b9a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/memberAnonymousObjects.fir.kt
@@ -0,0 +1,6 @@
+class Test {
+    private var x = object {};
+    init {
+        x = object {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/nestedIntoLocalClasses.fir.kt b/compiler/testData/diagnostics/tests/subtyping/nestedIntoLocalClasses.fir.kt
new file mode 100644
index 00000000000..bcd2f8e1689
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/nestedIntoLocalClasses.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER
+
+package p
+
+private fun foo(a: Int) = run {
+    object {
+        inner class A
+        fun foo() = A()
+    }.foo()
+}
+
+private fun foo() = run {
+    object {
+        inner class A
+        fun foo() = A()
+    }.foo()
+}
+
+fun test() {
+    var x = foo(1)
+    x = foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/nestedLocalClasses.fir.kt b/compiler/testData/diagnostics/tests/subtyping/nestedLocalClasses.fir.kt
new file mode 100644
index 00000000000..cfd165e6e6d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/nestedLocalClasses.fir.kt
@@ -0,0 +1,23 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE -UNUSED_VALUE -UNUSED_PARAMETER
+
+package p
+
+private fun foo(a: Int) = run {
+    class A {
+        inner class B
+    }
+    A().B()
+}
+
+private fun foo() = run {
+    class A {
+        inner class B
+    }
+    A().B()
+}
+
+fun test() {
+    var x = foo(1)
+    x = foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/topLevelAnonymousObjects.fir.kt b/compiler/testData/diagnostics/tests/subtyping/topLevelAnonymousObjects.fir.kt
new file mode 100644
index 00000000000..61a12cefa27
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/topLevelAnonymousObjects.fir.kt
@@ -0,0 +1,5 @@
+private var x = object {}
+
+fun test() {
+    x = object {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/subtyping/unresolvedSupertype.fir.kt b/compiler/testData/diagnostics/tests/subtyping/unresolvedSupertype.fir.kt
new file mode 100644
index 00000000000..077053d4845
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/subtyping/unresolvedSupertype.fir.kt
@@ -0,0 +1,7 @@
+interface A1 : B
+
+interface A2 : B()
+
+class A3 : B, B
+
+enum class A4 : B
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnAnonymousObjectInVariable.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnAnonymousObjectInVariable.fir.kt
new file mode 100644
index 00000000000..d623e09277f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnAnonymousObjectInVariable.fir.kt
@@ -0,0 +1,4 @@
+@Suppress("warnings")
+val anonymous = object {
+    fun foo(p: String?? = "" as String) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClass.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClass.fir.kt
new file mode 100644
index 00000000000..ee06a9d6554
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClass.fir.kt
@@ -0,0 +1,7 @@
+@Suppress("warnings")
+class C {
+    fun foo(p: String??) {
+        // Make sure errors are not suppressed:
+        p = ""
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClassObject.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClassObject.fir.kt
new file mode 100644
index 00000000000..5ada7c89028
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnClassObject.fir.kt
@@ -0,0 +1,6 @@
+class C {
+    @Suppress("warnings")
+    companion object {
+        val foo: String?? = null as Nothing?
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnExpression.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnExpression.fir.kt
new file mode 100644
index 00000000000..609b38cd708
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnExpression.fir.kt
@@ -0,0 +1,4 @@
+fun foo() {
+    @Suppress("warnings")
+    ("" as String??)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnFile.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnFile.fir.kt
new file mode 100644
index 00000000000..463e8a93fa4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnFile.fir.kt
@@ -0,0 +1,7 @@
+@file:Suppress("warnings")
+
+class C {
+    companion object {
+        val foo: String?? = null as Nothing?
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnFunction.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnFunction.fir.kt
new file mode 100644
index 00000000000..e3417c31183
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnFunction.fir.kt
@@ -0,0 +1,4 @@
+class C {
+    @Suppress("warnings")
+    fun foo(p: String??) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnObject.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnObject.fir.kt
new file mode 100644
index 00000000000..e7a06b4fbc5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnObject.fir.kt
@@ -0,0 +1,4 @@
+@Suppress("warnings")
+object C {
+    fun foo(p: String??) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnParameter.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnParameter.fir.kt
new file mode 100644
index 00000000000..de0d798413e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnParameter.fir.kt
@@ -0,0 +1,3 @@
+class C {
+    fun foo(@Suppress("warnings") p: String?? = "" as String) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnProperty.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnProperty.fir.kt
new file mode 100644
index 00000000000..d3bbb1f20b1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnProperty.fir.kt
@@ -0,0 +1,4 @@
+class C {
+    @Suppress("warnings")
+    val foo: String?? = null as Nothing?
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnPropertyAccessor.fir.kt b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnPropertyAccessor.fir.kt
new file mode 100644
index 00000000000..c79c536c4f8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/allWarnings/suppressWarningsOnPropertyAccessor.fir.kt
@@ -0,0 +1,5 @@
+class C {
+    val foo: String?
+        @Suppress("warnings")
+        get(): String?? = null as Nothing?
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/mixed.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/mixed.fir.kt
new file mode 100644
index 00000000000..910a1fed437
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/mixed.fir.kt
@@ -0,0 +1,5 @@
+@Suppress("REDUNDANT_NULLABLE")
+class C {
+    @Suppress("UNNECESSARY_NOT_NULL_ASSERTION")
+    fun foo(): String?? = ""!! as String??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onClass.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onClass.fir.kt
new file mode 100644
index 00000000000..e5383f85c76
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onClass.fir.kt
@@ -0,0 +1,4 @@
+@Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION")
+class C {
+    fun foo(): String?? = ""!! as String??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onClassObject.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onClassObject.fir.kt
new file mode 100644
index 00000000000..cbd26d1e736
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onClassObject.fir.kt
@@ -0,0 +1,6 @@
+class C {
+    @Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION")
+    companion object {
+        val foo: String?? = ""!! as String??
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onExpression.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onExpression.fir.kt
new file mode 100644
index 00000000000..6f5db5ebad7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onExpression.fir.kt
@@ -0,0 +1,4 @@
+fun foo(): Any? {
+    @Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION")
+    return ""!! as String??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onFunction.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onFunction.fir.kt
new file mode 100644
index 00000000000..8b67439ea4b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onFunction.fir.kt
@@ -0,0 +1,4 @@
+class C {
+    @Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION")
+    fun foo(): String?? = ""!! as String??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onObject.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onObject.fir.kt
new file mode 100644
index 00000000000..19d79d33090
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onObject.fir.kt
@@ -0,0 +1,4 @@
+@Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION")
+object C {
+    fun foo(): String?? = ""!! as String??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onParameter.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onParameter.fir.kt
new file mode 100644
index 00000000000..c3042fbe2ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onParameter.fir.kt
@@ -0,0 +1,3 @@
+class C {
+    fun foo(@Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION") p: String?? = ""!! as String??) = p
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onProperty.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onProperty.fir.kt
new file mode 100644
index 00000000000..7ef41bda7f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onProperty.fir.kt
@@ -0,0 +1,4 @@
+class C {
+    @Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION")
+    val foo: String?? = ""!! as String??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/manyWarnings/onPropertyAccessor.fir.kt b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onPropertyAccessor.fir.kt
new file mode 100644
index 00000000000..d2efda027b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/manyWarnings/onPropertyAccessor.fir.kt
@@ -0,0 +1,5 @@
+class C {
+    val foo: String?
+        @Suppress("REDUNDANT_NULLABLE", "UNNECESSARY_NOT_NULL_ASSERTION")
+        get(): String?? = ""!! as String??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onBlockStatement.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onBlockStatement.fir.kt
new file mode 100644
index 00000000000..0662798c80a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onBlockStatement.fir.kt
@@ -0,0 +1,60 @@
+fun <T : CharSequence> foo(x: Array<Any>, y: IntArray, block: (T, Int) -> Int) {
+    var r: Any?
+
+    @Suppress("UNCHECKED_CAST")
+    // comment
+    /* comment */
+    r = block(x[0] as T, "" as Int)
+
+    // to prevent unused assignment diagnostic for the above statement
+    r.hashCode()
+
+    var i = 1
+
+    if (i != 1) {
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[0] as T, "" as Int).toInt()
+    }
+
+    if (i != 1)
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[0] as T, "" as Int).toInt()
+
+    if (i != 2)
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[0] as T, "" as Int).toInt()
+    else
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[1] as T, "" as Int).toInt()
+
+    while (i != 1)
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[0] as T, "" as Int).toInt()
+
+    do
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[0] as T, "" as Int).toInt()
+    while (i != 1)
+
+    for (j in 1..100)
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[0] as T, "" as Int).toInt()
+
+    when (i) {
+        1 ->
+            @Suppress("UNCHECKED_CAST")
+            i += block(x[0] as T, "" as Int).toInt()
+    }
+
+    val l: () -> Unit = {
+        @Suppress("UNCHECKED_CAST")
+        i += block(x[0] as T, "" as Int).toInt()
+    }
+    l()
+
+    // many empty new lines
+    @Suppress("UNCHECKED_CAST")
+
+
+    y[i] += block(x[0] as T, "" as Int).toInt()
+}
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onBlockStatementSameLine.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onBlockStatementSameLine.fir.kt
new file mode 100644
index 00000000000..27ef5dbd823
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onBlockStatementSameLine.fir.kt
@@ -0,0 +1,19 @@
+fun <T : CharSequence> foo(x: Array<Any>, block: (T, Int) -> Int) {
+    var r: Any?
+
+    @Suppress("UNCHECKED_CAST") r = block(x[0] as T, "" as Int)
+
+    // to prevent unused assignment diagnostic for the above statement
+    r.<!INAPPLICABLE_CANDIDATE!>hashCode<!>()
+
+    var i = 1
+
+    if (i != 1) {
+        @Suppress("UNCHECKED_CAST") i += block(x[0] as T, "" as Int).toInt()
+    }
+
+    if (i != 1) @Suppress("UNCHECKED_CAST")
+    i += block(x[0] as T, "" as Int).toInt()
+
+    if (i != 1) @Suppress("UNCHECKED_CAST") i += block(x[0] as T, "" as Int).toInt()
+}
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onClass.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onClass.fir.kt
new file mode 100644
index 00000000000..bc71b4b2ecf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onClass.fir.kt
@@ -0,0 +1,4 @@
+@Suppress("REDUNDANT_NULLABLE")
+class C {
+    fun foo(): String?? = null as Nothing??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onClassObject.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onClassObject.fir.kt
new file mode 100644
index 00000000000..6ef18f496d1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onClassObject.fir.kt
@@ -0,0 +1,6 @@
+class C {
+    @Suppress("REDUNDANT_NULLABLE")
+    companion object {
+        val foo: String?? = null as Nothing??
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onExpression.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onExpression.fir.kt
new file mode 100644
index 00000000000..17c2f78894e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onExpression.fir.kt
@@ -0,0 +1,4 @@
+fun foo(): Any? {
+    @Suppress("REDUNDANT_NULLABLE")
+    return null as Nothing??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onFunction.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onFunction.fir.kt
new file mode 100644
index 00000000000..d8af00a55c7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onFunction.fir.kt
@@ -0,0 +1,4 @@
+class C {
+    @Suppress("REDUNDANT_NULLABLE")
+    fun foo(): String?? = null as Nothing??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onLocalVariable.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onLocalVariable.fir.kt
new file mode 100644
index 00000000000..36faabbcce5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onLocalVariable.fir.kt
@@ -0,0 +1,7 @@
+class C {
+    fun foo(): Any? {
+        @Suppress("REDUNDANT_NULLABLE")
+        val v: String?? = null as Nothing??
+        return v
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onObject.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onObject.fir.kt
new file mode 100644
index 00000000000..b23994c8df0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onObject.fir.kt
@@ -0,0 +1,4 @@
+@Suppress("REDUNDANT_NULLABLE")
+object C {
+    fun foo(): String?? = null as Nothing??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onParameter.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onParameter.fir.kt
new file mode 100644
index 00000000000..d475ca24ef6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onParameter.fir.kt
@@ -0,0 +1,3 @@
+class C {
+    fun foo(@Suppress("REDUNDANT_NULLABLE") p: String?? = null as Nothing??) = p
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onProperty.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onProperty.fir.kt
new file mode 100644
index 00000000000..e34ce0bd122
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onProperty.fir.kt
@@ -0,0 +1,4 @@
+class C {
+    @Suppress("REDUNDANT_NULLABLE")
+    val foo: String?? = null as Nothing?
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/suppress/oneWarning/onPropertyAccessor.fir.kt b/compiler/testData/diagnostics/tests/suppress/oneWarning/onPropertyAccessor.fir.kt
new file mode 100644
index 00000000000..06b586d33d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/suppress/oneWarning/onPropertyAccessor.fir.kt
@@ -0,0 +1,5 @@
+class C {
+    val foo: String?
+        @Suppress("REDUNDANT_NULLABLE")
+        get(): String?? = null as Nothing??
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/AbbreviationName.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/AbbreviationName.fir.kt
new file mode 100644
index 00000000000..112e586c4da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/AbbreviationName.fir.kt
@@ -0,0 +1,20 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.url = javaClass.url + "/"
+    javaClass.<!VARIABLE_EXPECTED!>htmlFile<!> += "1"
+
+    javaClass.<!UNRESOLVED_REFERENCE!>URL<!>
+    javaClass.<!UNRESOLVED_REFERENCE!>uRL<!>
+    javaClass.<!UNRESOLVED_REFERENCE!>HTMLFile<!>
+    javaClass.<!UNRESOLVED_REFERENCE!>hTMLFile<!>
+    javaClass.<!UNRESOLVED_REFERENCE!>htmlfile<!>
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public String getURL() { return true; }
+    public void setURL(String value) { }
+
+    public String getHTMLFile() { return true; }
+    public void setHTMLFile(String value) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Bases.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Bases.fir.kt
new file mode 100644
index 00000000000..0be689aa089
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Bases.fir.kt
@@ -0,0 +1,31 @@
+// FILE: KotlinFile.kt
+open class KotlinClass1 : JavaClass1() {
+    public fun getSomethingKotlin1(): Int = 1
+}
+
+class KotlinClass2 : JavaClass2() {
+    public fun getSomethingKotlin2(): Int = 1
+}
+
+fun foo(k: KotlinClass2) {
+    useInt(k.getSomething1())
+    useInt(k.something1)
+    useInt(k.getSomething2())
+    useInt(k.something2)
+    useInt(k.getSomethingKotlin1())
+    useInt(k.getSomethingKotlin2())
+    k.somethingKotlin1
+    k.somethingKotlin2
+}
+
+fun useInt(i: Int) {}
+
+// FILE: JavaClass1.java
+public class JavaClass1 {
+    public int getSomething1() { return 1; }
+}
+
+// FILE: JavaClass2.java
+public class JavaClass2 extends KotlinClass1 {
+    public int getSomething2() { return 1; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/CompiledClass.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/CompiledClass.fir.kt
new file mode 100644
index 00000000000..5415a21cea7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/CompiledClass.fir.kt
@@ -0,0 +1,6 @@
+// FILE: KotlinFile.kt
+import java.io.File
+
+fun foo(file: File) {
+    file.absolutePath.length
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Deprecated.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Deprecated.fir.kt
new file mode 100644
index 00000000000..83e9aa56d6b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Deprecated.fir.kt
@@ -0,0 +1,48 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.something1
+
+    javaClass.something2
+    javaClass.something2 = 1
+    javaClass.something2++
+
+    javaClass.something3
+    javaClass.something3 = 1
+    javaClass.something3++
+
+    javaClass.something4
+    javaClass.something4 = 1
+    javaClass.something4++
+
+    javaClass.something5
+    javaClass.something5 = 1
+    javaClass.something5++
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    @Deprecated
+    public int getSomething1() { return 1; }
+
+    @Deprecated
+    public int getSomething2() { return 1; }
+    public void setSomething2(int value) { }
+
+    public int getSomething3() { return 1; }
+    @Deprecated
+    public void setSomething3(int value) { }
+
+    @Deprecated
+    public int getSomething4() { return 1; }
+    @Deprecated
+    public void setSomething4(int value) { }
+
+    /**
+     * @deprecated Bla-bla-bla
+     */
+    public int getSomething5() { return 1; }
+    /**
+     * @deprecated Ha-ha-ha
+     */
+    public void setSomething5(int value) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FalseGetters.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FalseGetters.fir.kt
new file mode 100644
index 00000000000..15970ed546e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FalseGetters.fir.kt
@@ -0,0 +1,21 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.<!UNRESOLVED_REFERENCE!>something1<!>
+    javaClass.<!UNRESOLVED_REFERENCE!>something2<!>
+    javaClass.somethingStatic
+    javaClass.somethingVoid
+    javaClass.<!UNRESOLVED_REFERENCE!>ter<!>
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getSomething1(int p) { return p; }
+
+    public <T> T getSomething2() { return null; }
+
+    public static int getSomethingStatic() { return 1; }
+
+    public void getSomethingVoid() { }
+
+    public int getter() { return 1; }
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FalseSetters.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FalseSetters.fir.kt
new file mode 100644
index 00000000000..5d34a5a2fc5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FalseSetters.fir.kt
@@ -0,0 +1,26 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.something1++
+    javaClass.something2++
+    javaClass.something3++
+    javaClass.something4++
+    javaClass.something5 = null
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getSomething1() { return 1; }
+    public void setSomething1(int value, char c) { }
+
+    public int getSomething2() { return 1; }
+    public void setSomething2(String value) { }
+
+    public int getSomething3() { return 1; }
+    public <T> void setSomething3(int value) { return value; }
+
+    public int getSomething4() { return 1; }
+    public static void setSomething4(int value) { }
+
+    public int[] getSomething5() { return null; }
+    public void setSomething5(int... value) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FromTwoBases.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FromTwoBases.fir.kt
new file mode 100644
index 00000000000..d329ecc0d80
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/FromTwoBases.fir.kt
@@ -0,0 +1,19 @@
+// FILE: KotlinFile.kt
+
+interface C : A, B
+
+fun foo(c: C) {
+    c.setSomething(c.getSomething() + 1)
+    c.something++
+}
+
+// FILE: A.java
+public interface A {
+    int getSomething();
+}
+
+// FILE: B.java
+public interface B {
+    int getSomething();
+    void setSomething(int value);
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GenericClass.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GenericClass.fir.kt
new file mode 100644
index 00000000000..3d0b46e41d4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GenericClass.fir.kt
@@ -0,0 +1,10 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass<String>) {
+    javaClass.<!VARIABLE_EXPECTED!>something<!> += "x"
+}
+
+// FILE: JavaClass.java
+public class JavaClass<T> {
+    public T getSomething() { return null; }
+    public void setSomething(T value) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GetA.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GetA.fir.kt
new file mode 100644
index 00000000000..cd35f02613d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GetA.fir.kt
@@ -0,0 +1,10 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.a
+    javaClass.<!UNRESOLVED_REFERENCE!>A<!>
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getA() { return 1; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Getter.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Getter.fir.kt
new file mode 100644
index 00000000000..e8c069e2d88
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/Getter.fir.kt
@@ -0,0 +1,20 @@
+// FILE: KotlinFile.kt
+class KotlinClass {
+    public fun getSomething(): Int = 1
+}
+
+fun foo(javaClass: JavaClass, kotlinClass: KotlinClass) {
+    useInt(javaClass.getSomething())
+    useInt(javaClass.something)
+    javaClass.something = 1
+    javaClass.<!UNRESOLVED_REFERENCE!>Something<!>
+    useInt(kotlinClass.getSomething())
+    kotlinClass.something
+}
+
+fun useInt(i: Int) {}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getSomething() { return 1; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GetterAndSetter.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GetterAndSetter.fir.kt
new file mode 100644
index 00000000000..3bc634c4e43
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/GetterAndSetter.fir.kt
@@ -0,0 +1,14 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.something1++
+    javaClass.something2++
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getSomething1() { return 1; }
+    public void setSomething1(int value) { }
+
+    public int getSomething2() { return 1; }
+    public JavaClass setSomething2(int value) { return this; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/ImplicitReceiver.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/ImplicitReceiver.fir.kt
new file mode 100644
index 00000000000..084edcc7941
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/ImplicitReceiver.fir.kt
@@ -0,0 +1,12 @@
+// FILE: KotlinFile.kt
+fun JavaClass.foo() {
+    useInt(getSomething())
+    useInt(something)
+}
+
+fun useInt(i: Int) {}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getSomething() { return 1; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/IsNaming.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/IsNaming.fir.kt
new file mode 100644
index 00000000000..e133b761ebf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/IsNaming.fir.kt
@@ -0,0 +1,37 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.isSomething = !javaClass.isSomething
+    javaClass.isSomething2 = !javaClass.isSomething2
+
+    javaClass.<!UNRESOLVED_REFERENCE!>something<!>
+    javaClass.isSomethingWrong
+    javaClass.<!UNRESOLVED_REFERENCE!>somethingWrong<!>
+
+    javaClass.<!UNRESOLVED_REFERENCE!>issueFlag<!>
+    javaClass.<!UNRESOLVED_REFERENCE!>isSueFlag<!>
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public boolean isSomething() {
+        return true;
+    }
+
+    public void setSomething(boolean value) {
+    }
+
+    public boolean getIsSomething2() {
+        return true;
+    }
+
+    public void setIsSomething2(boolean value) {
+    }
+
+    public int isSomethingWrong() {
+        return 1;
+    }
+
+    public boolean issueFlag() {
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/JavaOverridesKotlin.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/JavaOverridesKotlin.fir.kt
new file mode 100644
index 00000000000..e1da3da8032
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/JavaOverridesKotlin.fir.kt
@@ -0,0 +1,29 @@
+// FILE: KotlinFile.kt
+open class KotlinClass {
+    public open fun getSomething1(): Int = 1
+
+    public open fun setSomething2(value: Int) {}
+}
+
+fun foo(javaClass: JavaClass) {
+    useInt(javaClass.getSomething1())
+    useInt(javaClass.something1)
+
+    javaClass.setSomething2(javaClass.getSomething2() + 1)
+    javaClass.something2 = javaClass.something2 + 1
+}
+
+fun useInt(i: Int) {}
+
+// FILE: JavaClass.java
+public class JavaClass extends KotlinClass implements JavaInterface {
+    public int getSomething1() { return 1; }
+
+    public int getSomething2() { return 1; }
+    public void setSomething2(int value) {}
+}
+
+// FILE: JavaInterface.java
+public class JavaInterface {
+    int getSomething2();
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava.fir.kt
new file mode 100644
index 00000000000..fe8193d4d92
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava.fir.kt
@@ -0,0 +1,52 @@
+// FILE: KotlinFile.kt
+abstract class KotlinClass : JavaClass(), KotlinInterface, JavaInterface {
+    override fun getSomething1(): Int = 1
+    override fun getSomething3(): String = ""
+    override fun setSomething4(value: String) {}
+    override fun getSomething5(): String = ""
+}
+
+interface KotlinInterface {
+    public fun getSomething1(): Int
+    public fun getSomething4(): String
+}
+
+fun foo(k: KotlinClass) {
+    useInt(k.getSomething1())
+    useInt(k.something1)
+
+    useInt(k.getSomething2())
+    useInt(k.something2)
+
+    useString(k.getSomething3())
+    useString(k.something3)
+
+    k.setSomething4("")
+    k.<!VARIABLE_EXPECTED!>something4<!> += ""
+    k.setSomething4(null)
+    k.something4 = null
+
+    useString(k.getSomething5())
+    useString(k.something5)
+    k.setSomething5(1)
+    k.something5 = 1
+}
+
+fun useInt(i: Int) {}
+fun useString(i: String) {}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getSomething1() { return 1; }
+    public int getSomething2() { return 1; }
+    public Object getSomething3() { return null; }
+}
+
+// FILE: JavaInterface.java
+public interface JavaInterface {
+    String getSomething4();
+    void setSomething4(String value);
+
+    Object getSomething5();
+    void setSomething5(Object value);
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava2.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava2.fir.kt
new file mode 100644
index 00000000000..458b84bfd6c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava2.fir.kt
@@ -0,0 +1,25 @@
+// FILE: KotlinFile.kt
+abstract class KotlinClass : JavaInterface1, JavaInterface2 {
+    override fun getSomething(): String = ""
+}
+
+fun foo(k: KotlinClass) {
+    useString(k.getSomething())
+    useString(k.something)
+    if (k.something == null) return
+
+    k.setSomething(1)
+    k.something = 1
+}
+
+fun useString(i: String) {}
+
+// FILE: JavaInterface1.java
+public interface JavaInterface1 {
+    String getSomething();
+}
+
+// FILE: JavaInterface2.java
+public interface JavaInterface2 {
+    void setSomething(int value);
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava3.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava3.fir.kt
new file mode 100644
index 00000000000..94a68b1f39e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava3.fir.kt
@@ -0,0 +1,25 @@
+// FILE: KotlinFile.kt
+abstract class KotlinClass : JavaInterface1, JavaInterface2 {
+    override fun getSomething(): String = ""
+}
+
+fun foo(k: KotlinClass) {
+    useString(k.getSomething())
+    useString(k.something)
+    if (k.something == null) return
+
+    k.setSomething("")
+    k.something = ""
+}
+
+fun useString(i: String) {}
+
+// FILE: JavaInterface1.java
+public interface JavaInterface1 {
+    String getSomething();
+}
+
+// FILE: JavaInterface2.java
+public interface JavaInterface2 {
+    void setSomething(String value);
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava4.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava4.fir.kt
new file mode 100644
index 00000000000..86376249db7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava4.fir.kt
@@ -0,0 +1,28 @@
+// FILE: KotlinFile.kt
+abstract class KotlinClass : JavaInterface3 {
+    override fun getSomething(): String = ""
+}
+
+fun foo(k: KotlinClass) {
+    useString(k.getSomething())
+    useString(k.something)
+    if (k.something == null) return
+
+    k.setSomething("")
+    k.something = ""
+}
+
+fun useString(i: String) {}
+
+// FILE: JavaInterface1.java
+public interface JavaInterface1 {
+    String getSomething();
+}
+
+// FILE: JavaInterface2.java
+public interface JavaInterface2 {
+    void setSomething(String value);
+}
+
+// FILE: JavaInterface3.java
+public interface JavaInterface3 extends JavaInterface1, JavaInterface2 {}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava5.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava5.fir.kt
new file mode 100644
index 00000000000..0c1ffd3f4bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/KotlinOverridesJava5.fir.kt
@@ -0,0 +1,29 @@
+// FILE: KotlinFile.kt
+abstract class KotlinClass : JavaInterface3 {
+    override fun getSomething(): String = ""
+}
+
+fun foo(k: KotlinClass) {
+    useString(k.getSomething())
+    useString(k.something)
+    if (k.something == null) return
+
+    k.setSomething("")
+    k.something = ""
+}
+
+fun useString(i: String) {}
+
+// FILE: JavaInterface1.java
+public interface JavaInterface1 {
+    String getSomething();
+}
+
+// FILE: JavaInterface2.java
+public interface JavaInterface2 {
+    String getSomething();
+    void setSomething(String value);
+}
+
+// FILE: JavaInterface3.java
+public interface JavaInterface3 extends JavaInterface1, JavaInterface2 {}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OnlyAscii.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OnlyAscii.fir.kt
new file mode 100644
index 00000000000..182df416a0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OnlyAscii.fir.kt
@@ -0,0 +1,22 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.КакоеТоСвойство = javaClass.КакоеТоСвойство + 1
+    javaClass.<!UNRESOLVED_REFERENCE!>какоеТоСвойство<!>
+
+    javaClass.КУ
+    javaClass.<!UNRESOLVED_REFERENCE!>ку<!>
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getКакоеТоСвойство() {
+        return 0;
+    }
+
+    public void setКакоеТоСвойство(int value) {
+    }
+
+    public int getКУ() {
+        return 0;
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OnlyPublic.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OnlyPublic.fir.kt
new file mode 100644
index 00000000000..90bc8cff6ba
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OnlyPublic.fir.kt
@@ -0,0 +1,22 @@
+// FILE: KotlinFile.kt
+package k
+
+import JavaClass
+
+fun foo(javaClass: JavaClass) {
+    javaClass.somethingPublic
+    javaClass.<!INAPPLICABLE_CANDIDATE!>somethingProtected<!>
+    javaClass.<!INAPPLICABLE_CANDIDATE!>somethingPrivate<!>
+    javaClass.<!INAPPLICABLE_CANDIDATE!>somethingPackage<!>
+    javaClass.somethingPublic = 1
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public int getSomethingPublic() { return 1; }
+    protected int getSomethingProtected() { return 1; }
+    private int getSomethingPrivate() { return 1; }
+    int getSomethingPackage() { return 1; }
+
+    protected void setSomethingPublic(int value) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.fir.kt
new file mode 100644
index 00000000000..e0e96602473
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/OverrideGetterOnly.fir.kt
@@ -0,0 +1,22 @@
+// FILE: KotlinFile.kt
+
+fun foo(o: JavaClass2) {
+    useString(o.something)
+    o.something = ""
+    o.setSomething(1)
+    o.something = 1 // we generate extension property for JavaClass2 with more specific type
+    o.<!VARIABLE_EXPECTED!>something<!> += "1"
+}
+
+fun useString(i: String) {}
+
+// FILE: JavaClass1.java
+public class JavaClass1 {
+    public Object getSomething() { return null; }
+    public void setSomething(Object value) { }
+}
+
+// FILE: JavaClass2.java
+public class JavaClass2 extends JavaClass1 {
+    public String getSomething() { return ""; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterHasHigherAccess.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterHasHigherAccess.fir.kt
new file mode 100644
index 00000000000..1d33ecdeeb6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterHasHigherAccess.fir.kt
@@ -0,0 +1,16 @@
+// FILE: KotlinFile.kt
+package k
+
+import JavaClass
+
+fun foo(javaClass: JavaClass) {
+    val v = javaClass.<!INAPPLICABLE_CANDIDATE!>something<!>
+    javaClass.<!INAPPLICABLE_CANDIDATE!>something<!> = 1
+    javaClass.<!INAPPLICABLE_CANDIDATE, INAPPLICABLE_CANDIDATE!>something<!><!UNRESOLVED_REFERENCE!>++<!>
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    protected int getSomething() { return 1; }
+    public void setSomething(int value) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterOnly.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterOnly.fir.kt
new file mode 100644
index 00000000000..9d3bef5eabe
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SetterOnly.fir.kt
@@ -0,0 +1,9 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.<!UNRESOLVED_REFERENCE!>something<!> = 1
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public void setSomething(int value) { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SmartCast.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SmartCast.fir.kt
new file mode 100644
index 00000000000..ab63b80a7a0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SmartCast.fir.kt
@@ -0,0 +1,28 @@
+// FILE: KotlinFile.kt
+fun foo(o: JavaInterface2): Int {
+    if (o is JavaClass) {
+        o.something++
+        return o.x + o.something2
+    }
+    return 0
+}
+
+// FILE: JavaClass.java
+public abstract class JavaClass extends BaseClass implements JavaInterface {
+    public int getSomething() { return 1; }
+    public void setSomething(int value) { }
+}
+
+// FILE: BaseClass.java
+public abstract class BaseClass implements JavaInterface {
+}
+
+// FILE: JavaInterface.java
+public interface JavaInterface {
+    int getX();
+}
+
+// FILE: JavaInterface2.java
+public interface JavaInterface2 {
+    int getSomething2();
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SmartCastImplicitReceiver.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SmartCastImplicitReceiver.fir.kt
new file mode 100644
index 00000000000..7da8bd686ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SmartCastImplicitReceiver.fir.kt
@@ -0,0 +1,23 @@
+// FILE: KotlinFile.kt
+fun Any.foo(): Int {
+    if (this is JavaClass) {
+        something++
+        return x
+    }
+    return 0
+}
+
+// FILE: JavaClass.java
+public abstract class JavaClass extends BaseClass implements JavaInterface {
+    public int getSomething() { return 1; }
+    public void setSomething(int value) { }
+}
+
+// FILE: BaseClass.java
+public abstract class BaseClass implements JavaInterface {
+}
+
+// FILE: JavaInterface.java
+public interface JavaInterface {
+    int getX();
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SyntheticJavaPropertyReference.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SyntheticJavaPropertyReference.fir.kt
new file mode 100644
index 00000000000..2d20cf8e244
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/SyntheticJavaPropertyReference.fir.kt
@@ -0,0 +1,9 @@
+// FILE: KotlinFile.kt
+
+fun bar() = JavaClass::foo
+
+// FILE: JavaClass.java
+
+public class JavaClass {
+    public String getFoo() {}
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/TypeAnnotation.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/TypeAnnotation.fir.kt
new file mode 100644
index 00000000000..65a01fde9de
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/TypeAnnotation.fir.kt
@@ -0,0 +1,13 @@
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.getSomething().<!INAPPLICABLE_CANDIDATE!>length<!>
+    javaClass.something.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+// FILE: JavaClass.java
+import org.jetbrains.annotations.*;
+
+public class JavaClass {
+    @Nullable
+    public String getSomething() { return null; }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/TypeParameterReceiver.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/TypeParameterReceiver.fir.kt
new file mode 100644
index 00000000000..c106a07c6da
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/javaProperties/TypeParameterReceiver.fir.kt
@@ -0,0 +1,16 @@
+// FILE: KotlinFile.kt
+
+fun <T: B> foo(t: T) {
+    t.setSomething(t.getSomething() + 1)
+    t.something++
+}
+
+// FILE: A.java
+public interface A {
+    int getSomething();
+}
+
+// FILE: B.java
+public interface B extends A {
+    void setSomething(int value);
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Deprecated.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Deprecated.fir.kt
new file mode 100644
index 00000000000..4f27061bd0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Deprecated.fir.kt
@@ -0,0 +1,22 @@
+// FILE: KotlinFile.kt
+public interface I {
+    public fun doIt()
+}
+
+fun foo(javaClass: JavaClass) {
+    javaClass.doSomething1 { bar() }
+    javaClass.doSomething2 { bar() }
+}
+
+fun bar(){}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    @Deprecated
+    public void doSomething1(Runnable runnable) { runnable.run(); }
+
+    /**
+     * @deprecated
+     */
+    public void doSomething2(Runnable runnable) { runnable.run(); }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericClass.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericClass.fir.kt
new file mode 100644
index 00000000000..9240e501a88
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericClass.fir.kt
@@ -0,0 +1,14 @@
+// JAVAC_EXPECTED_FILE
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass<String>): String {
+    return javaClass.doSomething("", 1) { s: String -> "" }
+}
+
+// FILE: JavaClass.java
+public class JavaClass<T> {
+    public T doSomething(T t, int anInt, I<T> i) { return t; }
+}
+
+interface I<T> {
+    T doIt(T t);
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericMethod.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericMethod.fir.kt
new file mode 100644
index 00000000000..26ff1b49544
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericMethod.fir.kt
@@ -0,0 +1,14 @@
+// JAVAC_EXPECTED_FILE
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass): String {
+    return javaClass.doSomething("") { <!UNRESOLVED_REFERENCE!>it<!> }
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public <T> T doSomething(T t, I<T> i) { return i.run(t); }
+}
+
+interface I<T> {
+    T run(T t);
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericMethodInGenericClass.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericMethodInGenericClass.fir.kt
new file mode 100644
index 00000000000..009c4d007bf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/GenericMethodInGenericClass.fir.kt
@@ -0,0 +1,16 @@
+// JAVAC_EXPECTED_FILE
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass<Int>) {
+    val a: String = javaClass.doSomething1("", 1) { p: String -> p }
+    val b: String = javaClass.doSomething2("", 1, true) { p: Int -> p }
+}
+
+// FILE: JavaClass.java
+public class JavaClass<X> {
+    public <T> T doSomething1(T t, X x, I<T> i) { return i.run(t); }
+    public <T> T doSomething2(T t, X x, boolean p, I<X> i) { return i.run(t); }
+}
+
+interface I<T> {
+    T run(T t);
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/InnerClassInGeneric.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/InnerClassInGeneric.fir.kt
new file mode 100644
index 00000000000..b5b053046f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/InnerClassInGeneric.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass<Int>): Int {
+    val inner = javaClass.createInner<String>()
+    return inner.doSomething(1, "") { }
+}
+
+// FILE: JavaClass.java
+public class JavaClass<T> {
+    public <X> Inner<X> createInner() {
+        return new Inner<X>();
+    }
+
+    public interface Inner<X>{
+        public T doSomething(T t, X x, Runnable runnable);
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/NoNamedArgsAllowed.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/NoNamedArgsAllowed.fir.kt
new file mode 100644
index 00000000000..ea53ff62635
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/NoNamedArgsAllowed.fir.kt
@@ -0,0 +1,14 @@
+// !WITH_NEW_INFERENCE
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.doSomething(p = 1) {
+        bar()
+    }
+}
+
+fun bar(){}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public void doSomething(int p, Runnable runnable) { runnable.run(); }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/PackageLocal.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/PackageLocal.fir.kt
new file mode 100644
index 00000000000..fadb8efd770
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/PackageLocal.fir.kt
@@ -0,0 +1,18 @@
+// FILE: KotlinFile1.kt
+package k
+
+import JavaClass
+
+fun foo(javaClass: JavaClass) {
+    javaClass.<!INAPPLICABLE_CANDIDATE!>doSomething<!> { }
+}
+
+// FILE: KotlinFile2.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.doSomething { }
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    void doSomething(Runnable runnable) { runnable.run(); }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/ParameterTypeAnnotation.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/ParameterTypeAnnotation.fir.kt
new file mode 100644
index 00000000000..eece4ba7e9e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/ParameterTypeAnnotation.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// FILE: KotlinFile.kt
+fun foo(javaInterface: JavaInterface) {
+    javaInterface.doIt(null) { }
+    javaInterface.doIt("", null)
+}
+
+// FILE: JavaInterface.java
+import org.jetbrains.annotations.*;
+
+public interface JavaInterface {
+    void doIt(@NotNull String s, @NotNull Runnable runnable);
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/PassNull.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/PassNull.fir.kt
new file mode 100644
index 00000000000..1bda1a5b3c0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/PassNull.fir.kt
@@ -0,0 +1,10 @@
+// FILE: KotlinFile.kt
+fun foo(javaInterface: JavaInterface) {
+    javaInterface.doIt(null, null) { }
+    javaInterface.doIt("", { }, null)
+}
+
+// FILE: JavaInterface.java
+public interface JavaInterface {
+    void doIt(String s, Runnable runnable1, Runnable runnable2);
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Private.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Private.fir.kt
new file mode 100644
index 00000000000..de8bd65a4ef
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Private.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+// FILE: KotlinFile.kt
+fun foo(javaClass: JavaClass) {
+    javaClass.<!INAPPLICABLE_CANDIDATE!>doSomething<!> { }
+}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    private void doSomething(Runnable runnable) { runnable.run(); }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Protected.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Protected.fir.kt
new file mode 100644
index 00000000000..4b93a1419dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Protected.fir.kt
@@ -0,0 +1,24 @@
+// FILE: KotlinFile.kt
+package k
+
+import JavaClass
+
+fun foo(javaClass: JavaClass) {
+    javaClass.<!INAPPLICABLE_CANDIDATE!>doSomething<!> {
+        bar()
+    }
+}
+
+class X : JavaClass() {
+    fun foo(other: JavaClass) {
+        doSomething { bar() }
+        other.doSomething { bar() }
+    }
+}
+
+fun bar(){}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    protected void doSomething(Runnable runnable) { runnable.run(); }
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/ReturnTypeAnnotation.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/ReturnTypeAnnotation.fir.kt
new file mode 100644
index 00000000000..bdf5d30e43e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/ReturnTypeAnnotation.fir.kt
@@ -0,0 +1,18 @@
+// FILE: KotlinFile.kt
+fun foo(javaInterface: JavaInterface) {
+    val value = javaInterface.compute { "" }
+    value.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+// FILE: JavaInterface.java
+import org.jetbrains.annotations.*;
+
+public interface JavaInterface {
+    @Nullable
+    <T> String compute(@NotNull Provider<T> provider);
+}
+
+// FILE: Provider.java
+public interface Provider<T> {
+    public T compute();
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Simple.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Simple.fir.kt
new file mode 100644
index 00000000000..33efc0e7495
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/Simple.fir.kt
@@ -0,0 +1,30 @@
+// FILE: KotlinFile.kt
+class KotlinClass {
+    public fun doSomething(runnable: Runnable) { runnable.run() }
+}
+
+public interface I {
+    public fun doIt()
+}
+
+fun foo(javaClass: JavaClass, kotlinClass: KotlinClass) {
+    javaClass.doSomething {
+        bar()
+    }
+
+    kotlinClass.doSomething {
+        bar()
+    }
+
+    javaClass.doSomething2 {
+        bar()
+    }
+}
+
+fun bar(){}
+
+// FILE: JavaClass.java
+public class JavaClass {
+    public void doSomething(Runnable runnable) { runnable.run(); }
+    public void doSomething2(I i) { i.doIt(); }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolution.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolution.fir.kt
new file mode 100644
index 00000000000..26b40b35e3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolution.fir.kt
@@ -0,0 +1,36 @@
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public int foo(Runnable r) { return 0; }
+    public String foo(Object r) { return null;}
+
+    public int bar(Runnable r) { return 1; }
+    public String bar(CharSequence r) { return null; }
+}
+
+// FILE: 1.kt
+fun fn() {}
+fun x(a: A, r: Runnable) {
+    a.foo(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.foo {} checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.foo(null) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.foo(Runnable { }) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.foo(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.foo(123) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    a.foo("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    a.bar(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.bar {} checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.bar(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.<!AMBIGUITY!>bar<!>(null)
+
+    a.bar(null as Runnable?) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.bar(null as CharSequence?) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    a.bar("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    a.<!INAPPLICABLE_CANDIDATE!>bar<!>(123)
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionStatic.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionStatic.fir.kt
new file mode 100644
index 00000000000..8010a01b4a1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionStatic.fir.kt
@@ -0,0 +1,36 @@
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public static int foo(Runnable r) { return 0; }
+    public static String foo(Object r) { return null;}
+
+    public static int bar(Runnable r) { return 1; }
+    public static String bar(CharSequence r) { return null; }
+}
+
+// FILE: 1.kt
+fun fn() {}
+fun x(r: Runnable) {
+    A.foo(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.foo {} checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    A.foo(null) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.foo(Runnable { }) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.foo(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    A.foo(123) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    A.foo("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    A.bar(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.bar {} checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    A.bar(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    A.<!AMBIGUITY!>bar<!>(null)
+
+    A.bar(null as Runnable?) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.bar(null as CharSequence?) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    A.bar("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    A.<!INAPPLICABLE_CANDIDATE!>bar<!>(123)
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionStaticWithoutRefinedSams.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionStaticWithoutRefinedSams.fir.kt
new file mode 100644
index 00000000000..5861cef2797
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionStaticWithoutRefinedSams.fir.kt
@@ -0,0 +1,37 @@
+// !LANGUAGE: -RefinedSamAdaptersPriority -NewInference
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public static int foo(Runnable r) { return 0; }
+    public static String foo(Object r) { return null;}
+
+    public static int bar(Runnable r) { return 1; }
+    public static String bar(CharSequence r) { return null; }
+}
+
+// FILE: 1.kt
+fun fn() {}
+fun x(r: Runnable) {
+    A.foo(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    A.foo {} checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    A.foo(null) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.foo(Runnable { }) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.foo(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    A.foo(123) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    A.foo("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    A.bar(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.bar {} checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    A.bar(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    A.<!AMBIGUITY!>bar<!>(null)
+
+    A.bar(null as Runnable?) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    A.bar(null as CharSequence?) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    A.bar("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    A.<!INAPPLICABLE_CANDIDATE!>bar<!>(123)
+}
diff --git a/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionWithoutRefinedSams.fir.kt b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionWithoutRefinedSams.fir.kt
new file mode 100644
index 00000000000..4f02afb50ed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/syntheticExtensions/samAdapters/overloadResolutionWithoutRefinedSams.fir.kt
@@ -0,0 +1,37 @@
+// !LANGUAGE: -RefinedSamAdaptersPriority -NewInference
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public int foo(Runnable r) { return 0; }
+    public String foo(Object r) { return null;}
+
+    public int bar(Runnable r) { return 1; }
+    public String bar(CharSequence r) { return null; }
+}
+
+// FILE: 1.kt
+fun fn() {}
+fun x(a: A, r: Runnable) {
+    a.foo(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    a.foo {} checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    a.foo(null) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.foo(Runnable { }) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.foo(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.foo(123) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    a.foo("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    a.bar(::fn) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.bar {} checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.bar(r) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.<!AMBIGUITY!>bar<!>(null)
+
+    a.bar(null as Runnable?) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    a.bar(null as CharSequence?) checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    a.bar("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    a.<!INAPPLICABLE_CANDIDATE!>bar<!>(123)
+}
diff --git a/compiler/testData/diagnostics/tests/tailRecOnVirtualMember.fir.kt b/compiler/testData/diagnostics/tests/tailRecOnVirtualMember.fir.kt
new file mode 100644
index 00000000000..12e7f3eb990
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/tailRecOnVirtualMember.fir.kt
@@ -0,0 +1,171 @@
+//!LANGUAGE: -ProhibitTailrecOnVirtualMember
+
+open class A {
+    tailrec open fun foo(x: Int) {
+        foo(x)
+    }
+
+    internal tailrec open fun bar(y: Int) {
+        bar(y)
+    }
+
+    protected tailrec open fun baz(y: Int) {
+        baz(y)
+    }
+
+    private tailrec fun boo(y: Int) {
+        boo(y)
+    }
+
+    internal tailrec fun baa(y: Int) {
+        baa(y)
+    }
+}
+
+open class B : A() {
+    final tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    final tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    final tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
+
+
+open class C : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
+
+object D : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y - 1)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
+
+sealed class E : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+
+    class E1 : E() {
+        tailrec override fun foo(x: Int) {
+            foo(x)
+        }
+
+        tailrec override fun bar(y: Int) {
+            bar(y)
+        }
+
+        tailrec override fun baz(y: Int) {
+            baz(y)
+        }
+    }
+}
+
+enum class F {
+    F0,
+    F1() {
+        tailrec override fun foo(x: Int) {
+            foo(x)
+        }
+
+        tailrec override fun bar(y: Int) {
+            bar(y)
+        }
+
+        tailrec override fun baz(y: Int) {
+            baz(y)
+        }
+    };
+
+    tailrec open fun foo(x: Int) {
+        foo(x)
+    }
+
+    internal tailrec open fun bar(y: Int) {
+        bar(y)
+    }
+
+    protected tailrec open fun baz(y: Int) {
+        baz(y)
+    }
+
+    private tailrec fun boo(y: Int) {
+        boo(y)
+    }
+
+    internal tailrec fun baa(y: Int) {
+        baa(y)
+    }
+}
+
+enum class G {
+
+    G1;
+
+    tailrec open fun foo(x: Int) {
+        foo(x)
+    }
+
+    internal tailrec open fun bar(y: Int) {
+        bar(y)
+    }
+
+    protected tailrec open fun baz(y: Int) {
+        baz(y)
+    }
+
+    private tailrec fun boo(y: Int) {
+        boo(y)
+    }
+
+    internal tailrec fun baa(y: Int) {
+        baa(y)
+    }
+}
+
+
+val z = object : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/tailRecOnVirtualMemberError.fir.kt b/compiler/testData/diagnostics/tests/tailRecOnVirtualMemberError.fir.kt
new file mode 100644
index 00000000000..c11063ead15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/tailRecOnVirtualMemberError.fir.kt
@@ -0,0 +1,170 @@
+//!LANGUAGE: +ProhibitTailrecOnVirtualMember
+
+open class A {
+    tailrec open fun foo(x: Int) {
+        foo(x)
+    }
+
+    internal tailrec open fun bar(y: Int) {
+        bar(y)
+    }
+
+    protected tailrec open fun baz(y: Int) {
+        baz(y)
+    }
+
+    private tailrec fun boo(y: Int) {
+        boo(y)
+    }
+
+    internal tailrec fun baa(y: Int) {
+        baa(y)
+    }
+}
+
+open class B : A() {
+    final tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    final tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    final tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
+
+
+open class C : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
+
+object D : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y - 1)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
+
+sealed class E : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+
+    class E1 : E() {
+        tailrec override fun foo(x: Int) {
+            foo(x)
+        }
+
+        tailrec override fun bar(y: Int) {
+            bar(y)
+        }
+
+        tailrec override fun baz(y: Int) {
+            baz(y)
+        }
+    }
+}
+
+enum class F {
+    F0,
+    F1() {
+        tailrec override fun foo(x: Int) {
+            foo(x)
+        }
+
+        tailrec override fun bar(y: Int) {
+            bar(y)
+        }
+
+        tailrec override fun baz(y: Int) {
+            baz(y)
+        }
+    };
+
+    tailrec open fun foo(x: Int) {
+        foo(x)
+    }
+
+    internal tailrec open fun bar(y: Int) {
+        bar(y)
+    }
+
+    protected tailrec open fun baz(y: Int) {
+        baz(y)
+    }
+
+    private tailrec fun boo(y: Int) {
+        boo(y)
+    }
+
+    internal tailrec fun baa(y: Int) {
+        baa(y)
+    }
+}
+
+enum class G {
+
+    G1;
+
+    tailrec open fun foo(x: Int) {
+        foo(x)
+    }
+
+    internal tailrec open fun bar(y: Int) {
+        bar(y)
+    }
+
+    protected tailrec open fun baz(y: Int) {
+        baz(y)
+    }
+
+    private tailrec fun boo(y: Int) {
+        boo(y)
+    }
+
+    internal tailrec fun baa(y: Int) {
+        baa(y)
+    }
+}
+
+val z = object : A() {
+    tailrec override fun foo(x: Int) {
+        foo(x)
+    }
+
+    tailrec override fun bar(y: Int) {
+        bar(y)
+    }
+
+    tailrec override fun baz(y: Int) {
+        baz(y)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/tailRecOverridden.fir.kt b/compiler/testData/diagnostics/tests/tailRecOverridden.fir.kt
new file mode 100644
index 00000000000..67f32ce524f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/tailRecOverridden.fir.kt
@@ -0,0 +1,32 @@
+// See also KT-4285
+open class A {
+    open fun foo(x: Int = 0) {}
+
+    open fun gav(y: Int = 1, z: Int = 2) {}
+}
+
+class B: A() {
+    tailrec override fun foo(x: Int) {
+        foo()
+    }
+
+    tailrec override fun gav(y: Int, z: Int) {
+        gav(y)
+    }
+
+    tailrec fun bar(y: Double): Double = bar(y * 2.0)
+}
+
+class C: A() {
+    tailrec override fun foo(x: Int) {
+        foo(0)
+    }
+
+    tailrec override fun gav(y: Int, z: Int) {
+        gav(y - 1, z - 1)
+    }
+
+    tailrec fun bar(y: Int = 1, z: Int = 2) {
+        bar(z)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/tailRecursionComplex.fir.kt b/compiler/testData/diagnostics/tests/tailRecursionComplex.fir.kt
new file mode 100644
index 00000000000..7fc93d8ff12
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/tailRecursionComplex.fir.kt
@@ -0,0 +1,16 @@
+object O {
+    // This is correct, foo is the same
+    tailrec fun foo(i: Int): Int = if (i < 0) 0 else O.foo(i - 1)
+}
+
+class A {
+    tailrec fun foo(i: Int) = if (i < 0) 0 else A.foo(i - 1)
+
+    companion object {
+        fun foo(i: Int) = 42 + i
+    }
+}
+
+class B {
+    tailrec fun foo(i: Int) = if (i < 0) 0 else O.foo(i - 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/basic.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/basic.fir.kt
new file mode 100644
index 00000000000..b20feb73784
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/basic.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PLATFORM_CLASS_MAPPED_TO_KOTLIN
+
+abstract class Test1 : Map<String, String> {
+    fun containsKey(key: String): Boolean = TODO()
+
+    fun getOrDefault(key: String, defaultValue: String): String = TODO()
+}
+
+abstract class Test2 : MutableMap<String, String> {
+    fun replace(key: String, value: String): String? = TODO()
+}
+
+abstract class Test3 : java.util.AbstractMap<String, String>() {
+    fun containsKey(key: String): Boolean = TODO()
+
+    fun replace(key: String, value: String): String? = TODO()
+}
+
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/delegation.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/delegation.fir.kt
new file mode 100644
index 00000000000..affebd4e03f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/delegation.fir.kt
@@ -0,0 +1,32 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PLATFORM_CLASS_MAPPED_TO_KOTLIN
+
+
+// Default methods from Java interfaces are NOT overridden by delegation.
+// So, in the example below 'TestNoDelegationToDefaultMethods#replace' implicitly overrides a method from 'java.util.Map' (which is ok),
+// but not a method from 'WithDelegation' (would be an error).
+open class WithDelegation(val m: Map<String, String>) : Map<String, String> by m
+
+class TestNoDelegationToDefaultMethods(m: Map<String, String>): WithDelegation(m) {
+    fun containsKey(key: String): Boolean = TODO()
+
+    fun getOrDefault(key: String, defaultValue: String): String = TODO()
+
+    fun replace(key: String, value: String): String? = TODO()
+}
+
+
+
+interface IBaseWithKotlinDeclaration : Map<String, String> {
+    fun replace(key: String, value: String): String?
+}
+
+abstract class WithDelegation2(val m: Map<String, String>) : Map<String, String> by m, IBaseWithKotlinDeclaration
+
+abstract class TestNoDelegationToDefaultMethods2(m: Map<String, String>): WithDelegation2(m) {
+    fun containsKey(key: String): Boolean = TODO()
+
+    fun getOrDefault(key: String, defaultValue: String): String = TODO()
+
+    // VIRTUAL_MEMBER_HIDDEN: hides member declaration inherited from a Kotlin interface
+    fun replace(key: String, value: String): String? = TODO()
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/derivedInterfaces.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/derivedInterfaces.fir.kt
new file mode 100644
index 00000000000..fbff5e5273d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/derivedInterfaces.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PLATFORM_CLASS_MAPPED_TO_KOTLIN
+
+interface IBase : Map<String, String>
+
+interface TestDerivedInterfaceHiding : IBase {
+    fun replace(key: String, value: String): String?
+}
+
+interface TestDerivedInterfaceDefault : IBase {
+    fun replace(key: String, value: String): String? = TODO()
+}
+
+
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/derivedInterfacesWithKotlinFun.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/derivedInterfacesWithKotlinFun.fir.kt
new file mode 100644
index 00000000000..bc6ac7dde3e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/derivedInterfacesWithKotlinFun.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PLATFORM_CLASS_MAPPED_TO_KOTLIN
+
+interface IBaseWithKotlinDeclaration : Map<String, String> {
+    fun replace(key: String, value: String): String?
+}
+
+interface TestDerivedInterfaceHidingWithKotlinDeclaration : IBaseWithKotlinDeclaration {
+    // VIRTUAL_MEMBER_HIDDEN: hides member declaration inherited from a Kotlin interface
+    fun replace(key: String, value: String): String?
+}
+
+interface TestDerivedInterfaceDefaultWithKotlinDeclaration : IBaseWithKotlinDeclaration {
+    // VIRTUAL_MEMBER_HIDDEN: hides member declaration inherited from a Kotlin interface
+    fun replace(key: String, value: String): String? = TODO()
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/fillInStackTrace.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/fillInStackTrace.fir.kt
new file mode 100644
index 00000000000..a9199de4138
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/fillInStackTrace.fir.kt
@@ -0,0 +1,4 @@
+// JAVAC_EXPECTED_FILE
+class ControlFlowException : Exception("") {
+    fun fillInStackTrace() = this
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/finalize.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/finalize.fir.kt
new file mode 100644
index 00000000000..914bf45c411
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/finalize.fir.kt
@@ -0,0 +1,10 @@
+enum class TestEnum {
+    ENTRY;
+
+    fun getDeclaringClass() {}
+    fun finalize() {}
+}
+
+class TestFinalize {
+    fun finalize() {}
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/hashMapGetOrDefault.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/hashMapGetOrDefault.fir.kt
new file mode 100644
index 00000000000..a06d4279cce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/hashMapGetOrDefault.fir.kt
@@ -0,0 +1,6 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PLATFORM_CLASS_MAPPED_TO_KOTLIN
+// JAVAC_EXPECTED_FILE
+
+class MyHashMap : java.util.HashMap<String, String>() {
+    fun getOrDefault(key: String, defaultValue: String): String = TODO()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/concurrentMapRemove.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/concurrentMapRemove.fir.kt
new file mode 100644
index 00000000000..047e151651d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/concurrentMapRemove.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+import java.util.concurrent.*
+
+val concurrent: ConcurrentMap<String, Int> = null!!
+val concurrentHash: ConcurrentHashMap<String, Int> = null!!
+
+fun foo() {
+    concurrent.remove("", 1)
+    concurrent.remove("", "")
+    concurrentHash.remove("", 1)
+    concurrentHash.remove("", "")
+
+    // Flexible types
+    concurrent.remove(null, 1)
+    concurrent.remove(null, null)
+
+    // @PurelyImplements
+    concurrentHash.remove(null, 1)
+    concurrentHash.remove(null, null)
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/forEachRemainingNullability.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/forEachRemainingNullability.fir.kt
new file mode 100644
index 00000000000..fb54c047784
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/forEachRemainingNullability.fir.kt
@@ -0,0 +1,41 @@
+// FULL_JDK
+
+import java.util.function.Consumer
+
+abstract class MyIt1<out T> : Iterator<T> {
+    override fun forEachRemaining(x: Consumer<in T>) {}
+}
+
+abstract class MyIt2<out T> : Iterator<T> {
+    override fun forEachRemaining(x: Consumer<in T?>) {}
+}
+
+abstract class MyIt3<out T> : Iterator<T> {
+    override fun forEachRemaining(x: Consumer<in T>?) {}
+}
+
+abstract class MyIt4 : Iterator<String?> {
+    override fun forEachRemaining(x: Consumer<in String?>) {}
+}
+
+abstract class MyIt5 : Iterator<String> {
+    override fun forEachRemaining(x: Consumer<in String>) {}
+}
+
+abstract class MyIt6 : Iterator<String?> {
+    override fun forEachRemaining(x: Consumer<in String>) {}
+}
+
+abstract class MyIt7 : Iterator<String> {
+    override fun forEachRemaining(x: Consumer<in String?>) {}
+}
+
+
+fun foo(x: Iterator<String>, y: Iterator<String?>) {
+    x.forEachRemaining(null)
+
+    x.forEachRemaining { it -> it.length }
+    x.forEachRemaining { it -> it?.length }
+    y.forEachRemaining { it -> it.<!INAPPLICABLE_CANDIDATE!>length<!> }
+    y.forEachRemaining { it -> it?.length }
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/getOrDefault.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/getOrDefault.fir.kt
new file mode 100644
index 00000000000..bdc7e807df9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/getOrDefault.fir.kt
@@ -0,0 +1,20 @@
+// FULL_JDK
+
+abstract class A : Map<Int, String>
+
+fun foo(x: Map<Int, String>, a: A, b: java.util.HashMap<Int, String>) {
+    x.getOrDefault(1, "")
+    x.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>("", "")
+    x.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>(1, 2)
+    x.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>("", 2)
+
+    a.getOrDefault(1, "")
+    a.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>("", "")
+    a.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>(1, 2)
+    a.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>("", 2)
+
+    b.getOrDefault(1, "")
+    b.getOrDefault("", "")
+    b.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>(1, 2)
+    b.<!INAPPLICABLE_CANDIDATE!>getOrDefault<!>("", 2)
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/mutableMapRemove.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/mutableMapRemove.fir.kt
new file mode 100644
index 00000000000..3f37343499b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/mutableMapRemove.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -PARAMETER_NAME_CHANGED_ON_OVERRIDE
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+class KotlinMap1<K, V> : java.util.AbstractMap<K, V>() {
+    override val entries: MutableSet<MutableMap.MutableEntry<K, V>>
+        get() = throw UnsupportedOperationException()
+
+    override fun remove(x: K, y: V) = true
+}
+
+class KotlinMap2 : java.util.AbstractMap<String, Int>() {
+    override val entries: MutableSet<MutableMap.MutableEntry<String, Int>>
+        get() = throw UnsupportedOperationException()
+
+    override fun remove(x: String, y: Int) = true
+}
+
+fun foo(x: MutableMap<String, Int>, y: java.util.HashMap<String, Int>, z: java.util.AbstractMap<String, Int>) {
+    x.remove("", 1)
+    x.<!INAPPLICABLE_CANDIDATE!>remove<!>("", "")
+    x.remove("", null)
+
+    y.remove("", 1)
+    y.remove("", "")
+    y.remove("", null)
+
+    z.remove("", 1)
+    z.<!INAPPLICABLE_CANDIDATE!>remove<!>("", "")
+    z.remove("", null)
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/removeIf.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/removeIf.fir.kt
new file mode 100644
index 00000000000..3ecc5f3048e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/removeIf.fir.kt
@@ -0,0 +1,12 @@
+// FULL_JDK
+
+import java.util.stream.*
+
+interface A : MutableCollection<String> {
+    override fun removeIf(x: java.util.function.Predicate<in String>) = false
+}
+
+fun foo(x: MutableList<String>, y: A) {
+    x.<!UNRESOLVED_REFERENCE!>removeIf<!> { <!UNRESOLVED_REFERENCE!>it<!>.<!UNRESOLVED_REFERENCE!>length<!> > 0 }
+    y.removeIf { it.length > 0 }
+}
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/stream.fir.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/stream.fir.kt
new file mode 100644
index 00000000000..ba756b281d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/stream.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+import java.util.stream.*
+
+interface A : Collection<String> {
+    override fun stream(): Stream<String> = Stream.of()
+}
+
+fun foo(x: List<String>, y: A) {
+    x.stream().filter { it.length > 0 }.<!INAPPLICABLE_CANDIDATE!>collect<!>(Collectors.toList())
+    y.stream().filter { it.length > 0 }
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/QualifiedThis.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/QualifiedThis.fir.kt
new file mode 100644
index 00000000000..f6a01a8db89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/QualifiedThis.fir.kt
@@ -0,0 +1,12 @@
+// FILE: f.kt
+class A() {
+  fun foo() : Unit {
+    this@A
+    this@a
+    this
+  }
+
+  val x = this@A.foo()
+  val y = this.foo()
+  val z = foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/Super.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/Super.fir.kt
new file mode 100644
index 00000000000..0f998cc8c11
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/Super.fir.kt
@@ -0,0 +1,64 @@
+package example
+
+interface T {
+    fun foo() {}
+}
+open class C() {
+    fun bar() {}
+}
+
+class A<E>() : C(), T {
+
+    fun test() {
+        super
+        super<T>
+        super.<!UNRESOLVED_REFERENCE!>foo<!>()
+        super<T>.foo()
+        super<C>.bar()
+        super<T>@A.foo()
+        super<C>@A.bar()
+        super<E>.<!UNRESOLVED_REFERENCE!>bar<!>()
+        super<E>@A.<!UNRESOLVED_REFERENCE!>bar<!>()
+        super<Int>.<!UNRESOLVED_REFERENCE!>foo<!>()
+        super<<!SYNTAX!><!>>.<!UNRESOLVED_REFERENCE!>foo<!>()
+        super<() -> Unit>.<!UNRESOLVED_REFERENCE!>foo<!>()
+        super<Unit>.<!UNRESOLVED_REFERENCE!>foo<!>()
+        super<T>@B.foo()
+        super<C>@B.bar()
+    }
+
+    inner class B : T {
+        fun test() {
+            super<T>.foo();
+            super<C>.bar()
+            super<C>@A.bar()
+            super<T>@A.foo()
+            super<T>@B.foo()
+            super<C>@B.<!UNRESOLVED_REFERENCE!>foo<!>()
+            super.foo()
+            super
+            super<T>
+        }
+    }
+}
+
+interface G<T> {
+    fun foo() {}
+}
+
+class CG : G<Int> {
+    fun test() {
+        super<G>.foo() // OK
+        super<G<Int>>.foo() // Warning
+        super<G<E>>.foo() // Error
+        super<G<String>>.foo() // Error
+    }
+}
+
+// The case when no supertype is resolved
+class ERROR<E>() : UR {
+
+    fun test() {
+        super.<!UNRESOLVED_REFERENCE!>foo<!>()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/ambigousLabelOnThis.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/ambigousLabelOnThis.fir.kt
new file mode 100644
index 00000000000..8fb5ae1f5d6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/ambigousLabelOnThis.fir.kt
@@ -0,0 +1,5 @@
+class Dup {
+  fun Dup() : Unit {
+    this@Dup
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/genericQualifiedSuperOverridden.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/genericQualifiedSuperOverridden.fir.kt
new file mode 100644
index 00000000000..a49b33534be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/genericQualifiedSuperOverridden.fir.kt
@@ -0,0 +1,19 @@
+interface IBase<T> {
+    fun foo() {}
+    fun bar() {}
+}
+
+interface IDerived<T> : IBase<T> {
+    override fun foo() {}
+    fun qux() {}
+}
+
+class Test : IDerived<String>, IBase<String> {
+    fun test() {
+        super<IBase>.foo()
+        super<IBase>.bar()
+        super<IDerived>.foo()
+        super<IDerived>.bar()
+        super<IDerived>.qux()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/implicitInvokeOnSuper.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/implicitInvokeOnSuper.fir.kt
new file mode 100644
index 00000000000..87fa9a1ce94
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/implicitInvokeOnSuper.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+open class A {
+    operator fun invoke() {}
+    operator fun invoke(f: () -> Unit) {}
+}
+
+class B : A() {
+    fun bar() {
+        super()
+        (super)()
+        super {}
+        (super) {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/notAccessibleSuperInTrait.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/notAccessibleSuperInTrait.fir.kt
new file mode 100644
index 00000000000..4d8bd0dc92f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/notAccessibleSuperInTrait.fir.kt
@@ -0,0 +1,10 @@
+open class A {
+    open fun foo() {}
+}
+
+interface ATrait : A {
+
+    override fun foo() {
+        super<A>.foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/qualifiedSuperOverridden.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/qualifiedSuperOverridden.fir.kt
new file mode 100644
index 00000000000..7965bd13a7b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/qualifiedSuperOverridden.fir.kt
@@ -0,0 +1,29 @@
+interface IBase {
+    fun foo() {}
+    fun bar() {}
+}
+
+interface IDerived1 : IBase {
+    override fun foo() {}
+    fun qux() {}
+}
+
+interface IDerived2 : IBase {
+    override fun foo() {}
+}
+
+class Test : IDerived1, IBase, IDerived2 {
+    override fun foo() {}
+
+    fun test() {
+        super<IBase>.foo()
+        super<IBase>.bar()
+
+        super<IDerived1>.foo()
+        super<IDerived1>.bar()
+        super<IDerived1>.qux()
+
+        super<IDerived2>.foo()
+        super<IDerived2>.bar()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/superInExtensionFunction.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/superInExtensionFunction.fir.kt
new file mode 100644
index 00000000000..6bb82a500f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/superInExtensionFunction.fir.kt
@@ -0,0 +1,4 @@
+fun String.f() {
+    <!NO_SUPERTYPE, NO_SUPERTYPE!>super@f<!>.<!UNRESOLVED_REFERENCE!>compareTo<!>("")
+    <!NO_SUPERTYPE, NO_SUPERTYPE!>super<!>.<!UNRESOLVED_REFERENCE!>compareTo<!>("")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/superInExtensionFunctionCall.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/superInExtensionFunctionCall.fir.kt
new file mode 100644
index 00000000000..3e04469afb2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/superInExtensionFunctionCall.fir.kt
@@ -0,0 +1,9 @@
+// No supertype at all
+
+fun Any.extension(arg: Any?) {}
+
+class A1 {
+    fun test() {
+        super.extension(null) // Call to an extension function
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/superInToplevelFunction.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/superInToplevelFunction.fir.kt
new file mode 100644
index 00000000000..7ff075f2363
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/superInToplevelFunction.fir.kt
@@ -0,0 +1,5 @@
+fun foo() {
+    <!NO_SUPERTYPE, NO_SUPERTYPE!>super<!>
+    <!NO_SUPERTYPE, NO_SUPERTYPE!>super<!>.<!UNRESOLVED_REFERENCE!>foo<!>()
+    super<Nothing>.<!UNRESOLVED_REFERENCE!>foo<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/superIsNotAnExpression.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/superIsNotAnExpression.fir.kt
new file mode 100644
index 00000000000..4a2dac7c651
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/superIsNotAnExpression.fir.kt
@@ -0,0 +1,12 @@
+fun any(a : Any) {}
+
+fun notAnExpression() {
+    any(<!NO_SUPERTYPE, NO_SUPERTYPE!>super<!>) // not an expression
+    if (<!NO_SUPERTYPE, NO_SUPERTYPE!>super<!>) {} else {} // not an expression
+    val x = <!NO_SUPERTYPE, NO_SUPERTYPE, NO_SUPERTYPE!>super<!> // not an expression
+    when (1) {
+        <!NO_SUPERTYPE, NO_SUPERTYPE!>super<!> -> 1 // not an expression
+        else -> {}
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/thisInFunctionLiterals.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/thisInFunctionLiterals.fir.kt
new file mode 100644
index 00000000000..c4d4e6382a6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/thisInFunctionLiterals.fir.kt
@@ -0,0 +1,18 @@
+// !CHECK_TYPE
+
+class A(val a:Int) {
+  inner class B() {
+    fun Byte.xx() : Double.() -> Any {
+      checkSubtype<Byte>(this)
+      val a: Double.() -> Unit = {
+        <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Double>(this)
+        checkSubtype<Byte>(this@xx)
+        checkSubtype<B>(this@B)
+        checkSubtype<A>(this@A)
+      }
+      val b: Double.() -> Unit = a@{ <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Double>(this@a) + checkSubtype<Byte>(this@xx) }
+      val c = a@{ -> this@a + checkSubtype<Byte>(this@xx) }
+      return (a@{<!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Double>(this@a) + checkSubtype<Byte>(this@xx)})
+    }
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/thisInInnerClasses.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/thisInInnerClasses.fir.kt
new file mode 100644
index 00000000000..37894b81581
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/thisInInnerClasses.fir.kt
@@ -0,0 +1,11 @@
+// !CHECK_TYPE
+
+class A(val a:Int) {
+
+  inner class B() {
+    val x = checkSubtype<B>(this@B)
+    val y = checkSubtype<A>(this@A)
+    val z = checkSubtype<B>(this)
+    val Int.xx : Int get() = checkSubtype<Int>(this)
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/thisInPropertyInitializer.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/thisInPropertyInitializer.fir.kt
new file mode 100644
index 00000000000..007d6e065bc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/thisInPropertyInitializer.fir.kt
@@ -0,0 +1,8 @@
+interface Base {
+    fun foo()
+}
+val String.test: Base = object: Base {
+    override fun foo() {
+        this@test
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/thisInToplevelFunction.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/thisInToplevelFunction.fir.kt
new file mode 100644
index 00000000000..34e17b1c77e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/thisInToplevelFunction.fir.kt
@@ -0,0 +1,4 @@
+fun foo1() : Unit {
+  this
+  this@a
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/traitSuperCall.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/traitSuperCall.fir.kt
new file mode 100644
index 00000000000..11485e6d46e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/traitSuperCall.fir.kt
@@ -0,0 +1,24 @@
+// FILE: test.kt
+
+public interface Test {
+    fun test(): String {
+        return "123";
+    }
+}
+
+interface KTrait : Test {
+    fun ktest() {
+        super.test()
+
+        test()
+    }
+}
+
+class A : KTrait {
+    fun b() {
+        super.test()
+
+        test()
+    }
+}
+
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/ambiguousSuperWithGenerics.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/ambiguousSuperWithGenerics.fir.kt
new file mode 100644
index 00000000000..23d89c88fac
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/ambiguousSuperWithGenerics.fir.kt
@@ -0,0 +1,38 @@
+// !WITH_NEW_INFERENCE
+open class GenericBaseClass<T> {
+    open fun foo(x: T): T = x
+    open fun ambiguous(x: T): T = x
+}
+
+interface GenericBaseInterface<T> {
+    fun bar(x: T): T = x
+    fun ambiguous(x: T): T = x
+}
+
+class GenericDerivedClass<T> : GenericBaseClass<T>(), GenericBaseInterface<T> {
+    override fun foo(x: T): T = super.foo(x)
+    override fun bar(x: T): T = super.<!UNRESOLVED_REFERENCE!>bar<!>(x)
+
+    override fun ambiguous(x: T): T =
+            super.ambiguous(x)
+}
+
+class SpecializedDerivedClass : GenericBaseClass<Int>(), GenericBaseInterface<String> {
+    override fun foo(x: Int): Int = super.foo(x)
+    override fun bar(x: String): String = super.<!UNRESOLVED_REFERENCE!>bar<!>(x)
+
+    override fun ambiguous(x: String): String =
+            super.<!INAPPLICABLE_CANDIDATE!>ambiguous<!>(x)
+    override fun ambiguous(x: Int): Int =
+            super.ambiguous(x)
+}
+
+class MixedDerivedClass<T> : GenericBaseClass<Int>(), GenericBaseInterface<T> {
+    override fun foo(x: Int): Int = super.foo(x)
+    override fun bar(x: T): T = super.<!UNRESOLVED_REFERENCE!>bar<!>(x)
+
+    override fun ambiguous(x: Int): Int =
+            super.ambiguous(x)
+    override fun ambiguous(x: T): T =
+            super.<!INAPPLICABLE_CANDIDATE!>ambiguous<!>(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuper.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuper.fir.kt
new file mode 100644
index 00000000000..74ce71eb7a5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuper.fir.kt
@@ -0,0 +1,57 @@
+//  Base  Interface
+//     \  /
+//      \/
+//    Derived
+//
+
+open class Base() {
+    open fun foo() {}
+
+    open fun ambiguous() {}
+
+    open val prop: Int
+        get() = 1234
+
+    open val ambiguousProp: Int
+        get() = 111
+}
+
+interface Interface {
+    fun bar() {}
+
+    fun ambiguous() {}
+
+    val ambiguousProp: Int
+        get() = 222
+}
+
+class Derived : Base(), Interface {
+    override fun foo() {}
+    override fun bar() {}
+
+    override fun ambiguous() {}
+
+    override val ambiguousProp: Int
+        get() = 333
+
+    override val prop: Int
+        get() = 4321
+
+    fun callsFunFromSuperClass() {
+        super.foo()
+    }
+
+    fun getSuperProp(): Int =
+            super.prop
+
+    fun getAmbiguousSuperProp(): Int =
+            super.ambiguousProp
+
+    fun callsFunFromSuperInterface() {
+        super.<!UNRESOLVED_REFERENCE!>bar<!>()
+    }
+
+    fun callsAmbiguousSuperFun() {
+        super.ambiguous()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithAbstractMembers.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithAbstractMembers.fir.kt
new file mode 100644
index 00000000000..8908eb77be2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithAbstractMembers.fir.kt
@@ -0,0 +1,39 @@
+// fun foo:     abstract in A,      unresolved in I
+// fun bar:     implemented in A,   abstract in I
+// fun qux:     abstract in A,      abstract in I
+// val x:       unresolved in A,    abstract in I
+// val y:       abstract in A,      implemented in I
+
+abstract class A {
+    abstract fun foo(): Int
+    open fun bar() {}
+    abstract fun qux()
+
+    abstract val y: Int
+}
+
+interface I {
+    fun bar()
+    fun qux()
+
+    val x: Int
+    val y: Int get() = 111
+}
+
+class B : A(), I {
+    override val x: Int = 12345
+    override val y: Int = super.y
+
+    override fun foo(): Int {
+        super.foo()
+        return super.<!UNRESOLVED_REFERENCE!>x<!>
+    }
+
+    override fun bar() {
+        super.bar()
+    }
+
+    override fun qux() {
+        super.qux()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithCallableProperty.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithCallableProperty.fir.kt
new file mode 100644
index 00000000000..0fa5ad351c5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithCallableProperty.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// Ambiguity between fun and callable property
+
+open class BaseWithCallableProp {
+    val fn = { "fn.invoke()" }
+
+    val bar = { "bar.invoke()"}
+    open fun bar(): String = "bar()"
+}
+
+interface InterfaceWithFun {
+    fun fn(): String = "fn()"
+}
+
+class DerivedUsingFun : BaseWithCallableProp(), InterfaceWithFun {
+    fun foo(): String =
+    super.fn()
+
+    override fun bar(): String =
+            super.bar()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithDeeperHierarchies.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithDeeperHierarchies.fir.kt
new file mode 100644
index 00000000000..a6f0af2a1b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithDeeperHierarchies.fir.kt
@@ -0,0 +1,51 @@
+// Check that it works with inherited members
+//
+//  DeeperBase  DeeperInterface
+//      |          |
+//  DeepBase    DeepInterface
+//          \  /
+//           \/
+//       DeepDerived
+//
+
+open class DeeperBase {
+    open fun deeperBaseFun() {}
+
+    open val deeperBaseProp: Int
+        get() = 333
+}
+
+open class DeepBase : DeeperBase() {
+}
+
+interface DeeperInterface {
+    fun deeperInterfaceFun() {}
+}
+
+interface DeepInterface : DeeperInterface {
+    fun deepInterfaceFun() {}
+}
+
+class DeepDerived : DeepBase(), DeepInterface {
+    override fun deeperBaseFun() {}
+
+    override val deeperBaseProp: Int
+        get() = 444
+
+    override fun deeperInterfaceFun() {}
+    override fun deepInterfaceFun() {}
+
+    fun callsSuperDeeperBaseFun() {
+        super.deeperBaseFun()
+    }
+
+    fun getsSuperDeeperBaseProp(): Int =
+            super.deeperBaseProp
+
+    fun callsSuperInterfaceFuns() {
+        super.<!UNRESOLVED_REFERENCE!>deeperInterfaceFun<!>()
+        super.<!UNRESOLVED_REFERENCE!>deepInterfaceFun<!>()
+        super<DeepInterface>.deeperInterfaceFun()
+        super<DeepInterface>.deepInterfaceFun()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithGenerics.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithGenerics.fir.kt
new file mode 100644
index 00000000000..0f9df74211a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithGenerics.fir.kt
@@ -0,0 +1,22 @@
+open class GenericBaseClass<T> {
+    open fun foo(x: T): T = x
+}
+
+interface GenericBaseInterface<T> {
+    fun bar(x: T): T = x
+}
+
+class GenericDerivedClass<T> : GenericBaseClass<T>(), GenericBaseInterface<T> {
+    override fun foo(x: T): T = super.foo(x)
+    override fun bar(x: T): T = super.<!UNRESOLVED_REFERENCE!>bar<!>(x)
+}
+
+class SpecializedDerivedClass : GenericBaseClass<Int>(), GenericBaseInterface<String> {
+    override fun foo(x: Int): Int = super.foo(x)
+    override fun bar(x: String): String = super.<!UNRESOLVED_REFERENCE!>bar<!>(x)
+}
+
+class MixedDerivedClass<T> : GenericBaseClass<Int>(), GenericBaseInterface<T> {
+    override fun foo(x: Int): Int = super.foo(x)
+    override fun bar(x: T): T = super.<!UNRESOLVED_REFERENCE!>bar<!>(x)
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithInnerClass.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithInnerClass.fir.kt
new file mode 100644
index 00000000000..414b53a7d0c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithInnerClass.fir.kt
@@ -0,0 +1,33 @@
+open class A {
+    open fun foo() {}
+}
+
+interface B {
+    fun bar() {}
+}
+
+interface Q {
+    fun qux() {}
+}
+
+class C : A(), B {
+    override fun foo() {
+        super@C.foo()
+    }
+
+    override fun bar() {
+        super@C.<!UNRESOLVED_REFERENCE!>bar<!>()
+    }
+
+    inner class D : A(), Q {
+        override fun foo() {
+            super@C.foo()
+            super@D.foo()
+        }
+
+        override fun qux() {
+            super@C.<!UNRESOLVED_REFERENCE!>qux<!>()
+            super@D.<!UNRESOLVED_REFERENCE!>qux<!>()
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithInterfaces.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithInterfaces.fir.kt
new file mode 100644
index 00000000000..749014aee50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithInterfaces.fir.kt
@@ -0,0 +1,28 @@
+//  Interface  AnotherInterface
+//          \  /
+//           \/
+//     DerivedInterface
+//
+
+interface Interface {
+    fun foo() {}
+    fun ambiguous() {}
+    val ambiguousProp: Int
+        get() = 222
+}
+
+interface AnotherInterface {
+    fun ambiguous() {}
+    val ambiguousProp: Int
+        get() = 333
+}
+
+interface DerivedInterface: Interface, AnotherInterface {
+    override fun foo() { super.foo() }
+    override fun ambiguous() {
+        super.ambiguous()
+    }
+    override val ambiguousProp: Int
+        get() = super.ambiguousProp
+}
+
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithLocalClass.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithLocalClass.fir.kt
new file mode 100644
index 00000000000..51bb88b6904
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithLocalClass.fir.kt
@@ -0,0 +1,21 @@
+interface Interface {
+    fun foo(x: Int): Int
+}
+
+fun withLocalClasses(param: Int): Interface {
+    open class LocalBase {
+        open val param: Int
+            get() = 100
+    }
+
+    interface LocalInterface : Interface {
+        override fun foo(x: Int): Int =
+                x + param
+    }
+
+    return object : LocalBase(), LocalInterface {
+        override fun foo(x: Int): Int =
+                x + super.param
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithUnresolvedBase.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithUnresolvedBase.fir.kt
new file mode 100644
index 00000000000..433959a2176
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/unqualifiedSuperWithUnresolvedBase.fir.kt
@@ -0,0 +1,53 @@
+// Check that unresolved super type doesn't interfere with unqualified super resolution.
+
+open class Base() {
+    open fun foo() {}
+
+    open fun ambiguous() {}
+
+    open val prop: Int
+        get() = 1234
+
+    open val ambiguousProp: Int
+        get() = 111
+}
+
+interface Interface {
+    fun bar() {}
+
+    fun ambiguous() {}
+
+    val ambiguousProp: Int
+        get() = 222
+}
+
+class ClassDerivedFromUnresolved : Base(), Interface, Unresolved {
+    override fun foo() {}
+    override fun bar() {}
+
+    override fun ambiguous() {}
+
+    override val ambiguousProp: Int
+        get() = 333
+
+    override val prop: Int
+        get() = 4321
+
+    fun callsFunFromSuperClass() {
+        super.foo()
+    }
+
+    fun getSuperProp(): Int =
+            super.prop
+
+    fun getAmbiguousSuperProp(): Int =
+    super.ambiguousProp
+
+    fun callsFunFromSuperInterface() {
+        super.<!UNRESOLVED_REFERENCE!>bar<!>()
+    }
+
+    fun callsAmbiguousSuperFun() {
+        super.ambiguous()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodOfAnyOverridenInInterface.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodOfAnyOverridenInInterface.fir.kt
new file mode 100644
index 00000000000..ba5f4f70298
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodOfAnyOverridenInInterface.fir.kt
@@ -0,0 +1,8 @@
+interface IWithToString {
+    override fun toString(): String
+}
+
+class A : IWithToString {
+    // Should be Any#toString(), even though IWithToString defines an abstract toString.
+    override fun toString(): String = super.toString()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodOverriddenInAnotherSupertype.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodOverriddenInAnotherSupertype.fir.kt
new file mode 100644
index 00000000000..2f18bb69586
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodOverriddenInAnotherSupertype.fir.kt
@@ -0,0 +1,29 @@
+interface A {
+    fun foo() {}
+}
+
+abstract class C : A {
+    override abstract fun foo()
+}
+
+interface Unrelated {
+    fun foo() {}
+}
+
+class Test1 : C(), A {
+    override fun foo() {
+        // Abstract 'foo' defined in 'C' wins against non-abstract 'foo' defined in 'A',
+        // because 'C' is a subclass of 'A' (and 'C::foo' overrides 'A::foo'),
+        // even though 'A' is explicitly listed in supertypes list for 'D'.
+        super.foo()
+    }
+}
+
+class Test2 : C(), A, Unrelated {
+    override fun foo() {
+        // This is ok, because there's a non-abstract 'foo' in 'Unrelated',
+        // which is not overridden by abstract 'foo' in 'C'.
+        super.foo()
+        super<Unrelated>.foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodsOfAny.fir.kt b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodsOfAny.fir.kt
new file mode 100644
index 00000000000..e61f5a4f19a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/thisAndSuper/unqualifiedSuper/withMethodsOfAny.fir.kt
@@ -0,0 +1,10 @@
+interface IFoo
+
+interface IBar
+
+class A : IFoo, IBar {
+    // Unqualified 'super' should be resolved to 'Any'.
+    override fun equals(other: Any?): Boolean = super.equals(other)
+    override fun hashCode(): Int = super.hashCode()
+    override fun toString(): String = super.toString()
+}
diff --git a/compiler/testData/diagnostics/tests/traitWithRequired/traitRequiresAny.fir.kt b/compiler/testData/diagnostics/tests/traitWithRequired/traitRequiresAny.fir.kt
new file mode 100644
index 00000000000..a0f84fee62f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/traitWithRequired/traitRequiresAny.fir.kt
@@ -0,0 +1,5 @@
+interface AnyTrait : Any
+
+class Foo : AnyTrait
+
+class Bar : AnyTrait, Any()
diff --git a/compiler/testData/diagnostics/tests/traitWithRequired/traitSupertypeList.fir.kt b/compiler/testData/diagnostics/tests/traitWithRequired/traitSupertypeList.fir.kt
new file mode 100644
index 00000000000..8ecc765977f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/traitWithRequired/traitSupertypeList.fir.kt
@@ -0,0 +1,10 @@
+open class bar()
+
+interface Foo() : bar(), bar, bar {
+}
+
+interface Foo2 : bar, Foo {
+}
+
+open class Foo1() : bar(), bar, Foo, <!UNRESOLVED_REFERENCE!>Foo<!>() {}
+open class Foo12 : bar(), bar {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typeParameters/cannotHaveManyClassUpperBounds.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/cannotHaveManyClassUpperBounds.fir.kt
new file mode 100644
index 00000000000..106db4f7c00
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/cannotHaveManyClassUpperBounds.fir.kt
@@ -0,0 +1,18 @@
+open class C1
+open class C2
+open class C3 : C2()
+
+class A1<T> where T : C1, T : C2
+class A2<T> where T : C1, T : C2, T : C3
+class A3<T> where T : C2, T : C3
+class A4<T> where T : C3, T : C2
+
+fun <T> f1() where T : C1, T : C2, T : C3 {}
+fun <T> f2() where T : C2, T : C3 {}
+fun <T> f3() where T : C3, T : C2 {}
+
+enum class E1
+class A5<T> where T : C1, T : E1
+
+object O1
+class A6<T> where T : O1, T : C2
diff --git a/compiler/testData/diagnostics/tests/typeParameters/deprecatedSyntax.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/deprecatedSyntax.fir.kt
new file mode 100644
index 00000000000..25cf191662a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/deprecatedSyntax.fir.kt
@@ -0,0 +1,3 @@
+fun foo<T>() {
+    fun bar<T>() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typeParameters/extFunctionTypeAsUpperBound.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/extFunctionTypeAsUpperBound.fir.kt
new file mode 100644
index 00000000000..e0683acd1be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/extFunctionTypeAsUpperBound.fir.kt
@@ -0,0 +1,7 @@
+fun <T: Int.() -> String> foo() {}
+
+val <T: Int.() -> String> bar = fun (x: Int): String { return x.toString() }
+
+class A<T> where T : Double.(Int) -> Unit
+
+interface B<T, U : T.() -> Unit>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typeParameters/functionTypeAsUpperBound.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/functionTypeAsUpperBound.fir.kt
new file mode 100644
index 00000000000..edd3dccff91
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/functionTypeAsUpperBound.fir.kt
@@ -0,0 +1,7 @@
+fun <T: (Int) -> String> foo() {}
+
+val <T: (kotlin.Int) -> kotlin.String> bar = fun (x: Int): String { return x.toString() }
+
+class A<T, U, V> where T : () -> Unit, U : (Int) -> Double, V : (T, U) -> U
+
+interface B<T, U : (T) -> Unit>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typeParameters/implicitNothingAsTypeParameter.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/implicitNothingAsTypeParameter.fir.kt
new file mode 100644
index 00000000000..4c3a94be300
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/implicitNothingAsTypeParameter.fir.kt
@@ -0,0 +1,103 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -UNCHECKED_CAST
+// !WITH_NEW_INFERENCE
+// SKIP_TXT
+// Issue: KT-20849
+
+fun <T>test_1(x: T): T = null as T
+fun <T>test_2(x: () -> T): T = null as T
+
+fun case_1() {
+    null?.run { return }
+    null!!.run { throw Exception() }
+}
+
+fun case_2() {
+    test_1 { null!! }
+    test_2 { null!! }
+}
+
+fun case_3() {
+    test_1 { throw Exception() }
+    test_2 { throw Exception() }
+}
+
+fun case_6() {
+    null!!
+}
+
+fun case_7(x: Boolean?) {
+    when (x) {
+        true -> throw Exception()
+        false -> throw Exception()
+        null -> throw Exception()
+    }
+}
+
+fun <T> something(): T = Any() as T
+
+class Context<T>
+
+fun <T> Any.decodeIn(typeFrom: Context<in T>): T = something()
+
+fun <T> Any?.decodeOut1(typeFrom: Context<out T>): T {
+    return this?.decodeIn(typeFrom) ?: kotlin.Unit
+}
+
+fun <T> Any.decodeOut2(typeFrom: Context<out T>): T {
+    val x: Nothing = this.decodeIn(typeFrom)
+}
+
+fun <T> Any.decodeOut3(typeFrom: Context<out T>): T {
+    val x = this.decodeIn(typeFrom)
+}
+
+fun <T> Any.decodeOut4(typeFrom: Context<out T>): T {
+    val x: Any = this.decodeIn(typeFrom)
+}
+
+class TrieNode<out E> {
+    companion object {
+        internal val EMPTY = TrieNode<Nothing>()
+    }
+}
+class PersistentHashSet<out E>(root: TrieNode<E>) {
+    companion object {
+        internal val EMPTY = PersistentHashSet(TrieNode.EMPTY)
+    }
+}
+
+interface F<in T>
+fun <T> F<T>.join() = {}
+
+fun main() {
+    val f: Any = Any()
+    (f as F<*>).join()
+}
+
+fun bug(worker: Worker<Unit>) {
+    stateless<Boolean, Nothing, Unit> {
+        onWorkerOutput(worker)
+    }
+}
+
+fun <StateT, OutputT : Any, T> RenderContext<StateT, OutputT>.onWorkerOutput(worker: Worker<T>): Unit = Unit
+
+fun <InputT, OutputT : Any, RenderingT> stateless(
+    render: RenderContext<Nothing, OutputT>.(input: InputT) -> RenderingT
+) { }
+
+interface Worker<out T>
+
+interface RenderContext<StateT, in OutputT : Any>
+
+val emptyOrNull: List<Nothing>? = null
+val x = emptyOrNull?.get(0)
+
+val errorCompletion = { e: Throwable -> throw Exception() }
+
+fun test1() {
+    errorCompletion(Exception("fail"))
+}
+fun test2() {
+    errorCompletion.invoke(Exception("fail"))
+}
diff --git a/compiler/testData/diagnostics/tests/typeParameters/implicitNothingOnDelegates.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/implicitNothingOnDelegates.fir.kt
new file mode 100644
index 00000000000..836fdbb4e77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/implicitNothingOnDelegates.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNCHECKED_CAST
+// !WITH_NEW_INFERENCE
+// WITH_RUNTIME
+// WITH_REFLECT
+// SKIP_TXT
+
+import kotlin.reflect.*
+
+private object Scope {
+    class Inv<T>
+
+    class Delegate<T>(private val p: Inv<in T>) {
+        operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
+            return materialize()
+        }
+    }
+
+    fun <T> materialize(): T = Any() as T
+
+    fun test(i: Inv<out Number>) {
+        val p: Int by Scope.Delegate(i)
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/typeParameters/misplacedConstraints.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/misplacedConstraints.fir.kt
new file mode 100644
index 00000000000..8e88088a0cc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/misplacedConstraints.fir.kt
@@ -0,0 +1,13 @@
+class Foo<T : Cloneable> where T : Comparable<T> {
+    fun <U : Cloneable> foo(u: U): U where U: Comparable<U> {
+        fun <T: Any> bar() where T: U {}
+        return u
+    }
+
+    val <U : Cloneable> U.foo: U? where U: Comparable<U>
+       get() { return null }
+}
+
+class Bar<T : Cloneable, U> where U: Comparable<T> {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typeParameters/propertyTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/propertyTypeParameters.fir.kt
new file mode 100644
index 00000000000..93872b99e62
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/propertyTypeParameters.fir.kt
@@ -0,0 +1,44 @@
+// !DIAGNOSTICS: -REDUNDANT_PROJECTION -CONFLICTING_PROJECTION
+
+interface G
+
+val <T> T.a: Int
+    get() = 3
+
+val <T1, T2> Map<T1, T2>.b: String
+    get() = "asds"
+
+val <T : G> G.c: Int get() = 5
+
+val <T1, T2, T3> List<Map<T2, T3>>.d: Int get() = 6
+
+val <T: Any> G.e: T?
+    get() = null
+
+val <T> List<Map<Int, Map<String, T>>>.f: Int get() = 7
+
+val <T> List<Map<Int, Map<String, out T>>>.g: Int get() = 7
+val <T> List<Map<Int, Map<String, in T>>>.h: Int get() = 7
+
+val <T> List<Map<T, Map<T, T>>>.i: Int get() = 7
+
+var <T1, T2, T3, T4> p = 1
+
+class C<T1, T2> {
+    val <E> T1.a: Int get() = 3
+    val <E> T2.b: Int get() = 3
+    val <E> E.c: Int get() = 3
+    val <E> Map<T1, T2>.d: Int get() = 3
+    val <E> Map<T1, E>.e: Int get() = 3
+}
+
+val <T : Enum<T>> T.z1: Int
+    get() = 4
+
+interface D<T : Enum<T>>
+
+val <X: D<*>> X.z2: Int
+    get() = 4
+
+val <Y> D<*>.z3: Int
+    get() = 4
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typeParameters/propertyTypeParametersWithUpperBounds.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/propertyTypeParametersWithUpperBounds.fir.kt
new file mode 100644
index 00000000000..4f3ea1b2bca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/propertyTypeParametersWithUpperBounds.fir.kt
@@ -0,0 +1,28 @@
+
+val <T : K, K> K.a: Int get() = 4
+
+val <T, K> K.b: Int where T : K
+    get() = 4
+
+val <T, K> K.c: Int where T : List<K>
+    get() = 4
+
+val <T, K> K.d: Int where K : T
+    get() = 4
+
+val <T, K> K.e: Int where K : List<T>
+    get() = 4
+
+interface G
+val <T> G.x1: Int where T : G
+    get() = 4
+
+
+val <X, Y, Z> Z.x2: Int where X : Y, Z : Y
+    get() = 4
+
+val <X, Y: Map<Z, X>, Z: List<List<Y>>> Z.x3: Int
+    get() = 5
+
+val <X, Y: Map<X, List<Z>>, Z> Map<X, List<Y>>.x4: Int
+    get() = 5
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typeParameters/repeatedBound.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/repeatedBound.fir.kt
new file mode 100644
index 00000000000..9364f6ab3c1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/repeatedBound.fir.kt
@@ -0,0 +1,7 @@
+interface I1
+
+class A1<T> where T : I1, T : I1
+class A2<T> where T : I1, T : I1?
+class A3<K, V> where K : V, K : V
+
+fun <T> f1() where T : I1, T : I1 {}
diff --git a/compiler/testData/diagnostics/tests/typeParameters/upperBoundCannotBeArray.fir.kt b/compiler/testData/diagnostics/tests/typeParameters/upperBoundCannotBeArray.fir.kt
new file mode 100644
index 00000000000..1edf45e1e0f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typeParameters/upperBoundCannotBeArray.fir.kt
@@ -0,0 +1,18 @@
+fun <A : Array<Any>> f1() {}
+fun <T, A : Array<out T>> f2() {}
+fun <S, T : S, A> f3() where A : Array<out S>, A : Array<out T> {}
+
+fun <T : IntArray> f4() {}
+
+fun <T> f5() where T : Array<Any> {}
+
+val <T : Array<Any?>> T.v: String get() = ""
+
+class C2<T, A : Array<out T>>
+interface C3<S, T : S, A> where A : Array<out S>, A : Array<out T>
+
+fun foo() {
+    class C1<A : Array<Any>> {
+        fun <A : Array<Any>, B : Array<Any>, C : A> f() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/aliasesOnly.fir.kt b/compiler/testData/diagnostics/tests/typealias/aliasesOnly.fir.kt
new file mode 100644
index 00000000000..6d283e0cf15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/aliasesOnly.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+typealias S = String
+
+class C {
+    typealias SS = String
+    typealias SF<T> = (T) -> String
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/annotationsOnTypeAliases.fir.kt b/compiler/testData/diagnostics/tests/typealias/annotationsOnTypeAliases.fir.kt
new file mode 100644
index 00000000000..c31ba56353d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/annotationsOnTypeAliases.fir.kt
@@ -0,0 +1,15 @@
+// WITH_RUNTIME
+import kotlin.annotation.AnnotationTarget.*
+
+annotation class NoTarget
+
+@Target(CLASS)
+annotation class IrrelevantTarget
+
+@Target(TYPEALIAS)
+annotation class TypealiasTarget
+
+@NoTarget
+@IrrelevantTarget
+@TypealiasTarget
+typealias Test = String
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/boundViolationInTypeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/boundViolationInTypeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..8b7607144f6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/boundViolationInTypeAliasConstructor.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+class Num<T: Number>(val x: T)
+
+typealias N<T> = Num<T>
+typealias N2<T> = N<T>
+
+val x1 = <!INAPPLICABLE_CANDIDATE!>Num<!><String>("")
+val x2 = N<String>("")
+val x3 = N2<String>("")
+
+class TColl<T, C : Collection<T>>
+
+typealias TC<T, C> = TColl<T, C>
+typealias TC2<T, C> = TC<T, C>
+
+val y1 = TColl<Any, Any>()
+val y2 = TC<Any, Any>()
+val y3 = TC2<Any, Any>()
diff --git a/compiler/testData/diagnostics/tests/typealias/boundsViolationInDeepTypeAliasExpansion.fir.kt b/compiler/testData/diagnostics/tests/typealias/boundsViolationInDeepTypeAliasExpansion.fir.kt
new file mode 100644
index 00000000000..c868b92be74
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/boundsViolationInDeepTypeAliasExpansion.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+class TColl<T, C : Collection<T>>
+
+typealias TC<T1, T2> = TColl<T1, T2>
+typealias TC2<T1, T2> = TC<T1, T2>
+
+fun test1(x: TC2<Number, Collection<Number>>) {}
+fun test2(x: TC2<Number, Collection<Int>>) {}
+fun test3(x: TC2<Number, List<Int>>) {}
+fun test4(x: TC2<Number, List<Any>>) {}
+
+val test5 = TC2<Number, Collection<Number>>()
+val test6 = TC2<Number, Collection<Int>>()
+val test7 = TC2<Number, List<Int>>()
+val test8 = TC2<Number, List<Any>>()
diff --git a/compiler/testData/diagnostics/tests/typealias/boundsViolationInTypeAliasExpansion.fir.kt b/compiler/testData/diagnostics/tests/typealias/boundsViolationInTypeAliasExpansion.fir.kt
new file mode 100644
index 00000000000..dd2a35d6211
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/boundsViolationInTypeAliasExpansion.fir.kt
@@ -0,0 +1,30 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+class Num<T : Number>
+class NumColl<T : Collection<Number>>
+class TColl<T, C : Collection<T>>
+
+typealias NA<T> = Num<T>
+typealias NL<T> = NumColl<List<T>>
+typealias TC<T1, T2> = TColl<T1, T2>
+
+fun test1(x: NA<Int>) {}
+fun test2(x: NA<Any>) {}
+fun test3(x: NL<Int>) {}
+fun test4(x: NL<Any>) {}
+
+val test5 = NA<Int>()
+val test6 = NA<Any>()
+val test7 = NL<Int>()
+val test8 = NL<Any>()
+
+fun test9(x: TC<Number, Collection<Number>>) {}
+fun test10(x: TC<Number, Collection<Int>>) {}
+fun test11(x: TC<Number, List<Int>>) {}
+fun test12(x: TC<Number, List<Any>>) {}
+
+val test13 = TC<Number, Collection<Number>>()
+val test14 = TC<Number, Collection<Int>>()
+val test15 = TC<Number, List<Int>>()
+val test16 = TC<Number, List<Any>>()
diff --git a/compiler/testData/diagnostics/tests/typealias/boundsViolationInTypeAliasRHS.fir.kt b/compiler/testData/diagnostics/tests/typealias/boundsViolationInTypeAliasRHS.fir.kt
new file mode 100644
index 00000000000..7d71da84dce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/boundsViolationInTypeAliasRHS.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+class TC<T, C : Collection<T>>
+
+typealias TCAlias<T, C> = TC<T, C>
+typealias TCAliasT<T> = TC<T, Any>
+typealias TCAliasC<C> = TC<Any, C>
+typealias TCAliasT1<T> = TCAlias<T, Any>
+typealias TCAliasC1<C> = TCAlias<Any, C>
+
+typealias Test1 = TC<Any, Any>
+typealias Test2 = TC<Any, Collection<Any>>
+typealias Test3 = TCAlias<Any, Any>
+typealias Test4 = TCAlias<Any, Collection<Any>>
+typealias Test5 = TCAliasT<Any>
+typealias Test6 = TCAliasC<Any>
+typealias Test7 = TCAliasC<Collection<Any>>
+typealias Test8 = TCAliasT1<Any>
+typealias Test9 = TCAliasC1<Any>
+typealias Test10 = TCAliasC1<Collection<Any>>
diff --git a/compiler/testData/diagnostics/tests/typealias/capturingTypeParametersFromOuterClass.fir.kt b/compiler/testData/diagnostics/tests/typealias/capturingTypeParametersFromOuterClass.fir.kt
new file mode 100644
index 00000000000..377d2af6c7d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/capturingTypeParametersFromOuterClass.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class Outer<TO> {
+    typealias LTO = List<TO>
+
+    class Nested<TN> {
+        typealias LTO = List<TO>
+        typealias LTN = List<TN>
+
+        inner class Inner<TI> {
+            typealias LTO = List<TO>
+            typealias LTN = List<TN>
+            typealias LTI = List<TI>
+        }
+    }
+}
+
+fun <TF> foo() {
+    class Local<TL> {
+        typealias LTF = List<TF>
+        typealias LTL = List<TL>
+    }
+
+    fun <TLF> localfun() =
+            object {
+                typealias LTF = List<TF>
+                typealias LTLF = List<TLF>
+            }
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/classReference.fir.kt b/compiler/testData/diagnostics/tests/typealias/classReference.fir.kt
new file mode 100644
index 00000000000..33c74a0eb4a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/classReference.fir.kt
@@ -0,0 +1,3 @@
+typealias S = String
+
+val s = S::class
diff --git a/compiler/testData/diagnostics/tests/typealias/conflictingProjections.fir.kt b/compiler/testData/diagnostics/tests/typealias/conflictingProjections.fir.kt
new file mode 100644
index 00000000000..eb078eb386a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/conflictingProjections.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+interface In<in T>
+interface Out<out T>
+
+typealias InAlias<T> = In<T>
+typealias OutAlias<T> = Out<T>
+
+typealias TestOutForIn<T> = In<out T>
+typealias TestInForOut<T> = Out<in T>
+
+typealias TestOutForInWithinAlias<T> = InAlias<out T>
+typealias TestInForOutWithinAlias<T> = OutAlias<in T>
+
+fun <T> testOutForInWithinResolvedType(x: InAlias<out T>) {}
+fun <T> testInForOutWithinResolvedType(x: OutAlias<in T>) {}
diff --git a/compiler/testData/diagnostics/tests/typealias/constructorCallThroughPrivateAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/constructorCallThroughPrivateAlias.fir.kt
new file mode 100644
index 00000000000..777b7a75749
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/constructorCallThroughPrivateAlias.fir.kt
@@ -0,0 +1,29 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !CHECK_TYPE
+// FILE: a.kt
+package a
+
+class B(x: String)
+typealias A1 = B
+private typealias A2 = B
+private typealias A3 = B
+
+fun A3(x: Any) = "OK"
+
+fun bar() {
+    A3("") checkType { <!UNRESOLVED_REFERENCE!>_<!><B>() }
+}
+
+// FILE: main.kt
+package usage
+
+import a.B
+
+fun baz() {
+    a.A1("") // resolved to B constructor, OK
+    a.A2("") // resolved to B constructor, INVISIBLE_MEMBER because type alias is private, OK
+
+    a.A3("") checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    val x: a.A2 = B("") // A2 is unresolved because it's private in file, OK
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/cyclicInheritanceViaTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/cyclicInheritanceViaTypeAlias.fir.kt
new file mode 100644
index 00000000000..2943e8b4c4e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/cyclicInheritanceViaTypeAlias.fir.kt
@@ -0,0 +1,7 @@
+class A : B() {
+    open class Nested<T>
+}
+
+typealias ANested<T> = A.Nested<T>
+
+open class B : ANested<Int>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/enumEntryQualifier.fir.kt b/compiler/testData/diagnostics/tests/typealias/enumEntryQualifier.fir.kt
new file mode 100644
index 00000000000..95a0fd48338
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/enumEntryQualifier.fir.kt
@@ -0,0 +1,6 @@
+enum class MyEnum { A }
+
+typealias TestAlias = MyEnum
+
+val test1 = MyEnum.A
+val test2 = TestAlias.<!UNRESOLVED_REFERENCE!>A<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/exposedExpandedType.fir.kt b/compiler/testData/diagnostics/tests/typealias/exposedExpandedType.fir.kt
new file mode 100644
index 00000000000..2b9ab13235f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/exposedExpandedType.fir.kt
@@ -0,0 +1,45 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+typealias L<T> = List<T>
+
+class Outer {
+    private class Private
+    protected class Protected
+    internal class Internal
+
+    typealias TestPrivate1 = Private
+    protected typealias TestPrivate2 = Private
+    internal typealias TestPrivate3 = Private
+    private typealias TestPrivate4 = Private
+    typealias TestPrivate5 = L<Private>
+    typealias TestPrivate6 = L<TestPrivate1>
+
+    typealias TestProtected1 = Protected
+    protected typealias TestProtected2 = Protected
+    internal typealias TestProtected3 = Protected
+    private typealias TestProtected4 = Protected
+    typealias TestProtected5 = L<Protected>
+    typealias TestProtected6 = L<TestProtected1>
+
+    typealias TestInternal1 = Internal
+    protected typealias TestInternal2 = Internal
+    internal typealias TestInternal3 = Internal
+    private typealias TestInternal4 = Internal
+    typealias TestInternal5 = L<Internal>
+    typealias TestInternal6 = L<TestInternal1>
+}
+
+private class Private
+internal class Internal
+
+typealias TestPrivate1 = Private
+internal typealias TestPrivate2 = Private
+private typealias TestPrivate3 = Private
+typealias TestPrivate4 = L<Private>
+typealias TestPrivate5 = L<TestPrivate1>
+
+typealias TestInternal1 = Internal
+internal typealias TestInternal2 = Internal
+private typealias TestInternal3 = Internal
+typealias TestInternal4 = L<Internal>
+typealias TestInternal5 = L<TestInternal1>
diff --git a/compiler/testData/diagnostics/tests/typealias/functionTypeInTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/functionTypeInTypeAlias.fir.kt
new file mode 100644
index 00000000000..d1b1e45332e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/functionTypeInTypeAlias.fir.kt
@@ -0,0 +1,3 @@
+val f: () -> Unit = {}
+
+typealias F = () -> Unit
diff --git a/compiler/testData/diagnostics/tests/typealias/genericTypeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/genericTypeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..fd683ffa156
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/genericTypeAliasConstructor.fir.kt
@@ -0,0 +1,10 @@
+class C<T>(val x: T, val y: String) {
+    constructor(x: T): this(x, "")
+}
+
+typealias GTC<T> = C<T>
+
+val test1 = GTC<String>("", "")
+val test2 = GTC<String>("", "")
+val test3 = GTC<String>("")
+val test4 = GTC<String>("")
diff --git a/compiler/testData/diagnostics/tests/typealias/genericTypeAliasObject.fir.kt b/compiler/testData/diagnostics/tests/typealias/genericTypeAliasObject.fir.kt
new file mode 100644
index 00000000000..d301b19d0cd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/genericTypeAliasObject.fir.kt
@@ -0,0 +1,25 @@
+object AnObject {
+    val ok = "OK"
+    fun foo() = "OK"
+}
+
+typealias GenericTestObject<T> = AnObject
+
+val test11: AnObject = GenericTestObject
+val test12: GenericTestObject<*> = GenericTestObject
+val test13: String = GenericTestObject.<!UNRESOLVED_REFERENCE!>ok<!>
+val test14: String = GenericTestObject.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+class GenericClassWithCompanion<T> {
+    companion object {
+        val ok = "OK"
+        fun foo() = "OK"
+    }
+}
+
+typealias TestGCWC<T> = GenericClassWithCompanion<T>
+
+val test25: GenericClassWithCompanion.Companion = TestGCWC
+val test26 = TestGCWC
+val test27: String = TestGCWC.<!UNRESOLVED_REFERENCE!>ok<!>
+val test28: String = TestGCWC.<!UNRESOLVED_REFERENCE!>foo<!>()
diff --git a/compiler/testData/diagnostics/tests/typealias/illegalTypeInTypeAliasExpansion.fir.kt b/compiler/testData/diagnostics/tests/typealias/illegalTypeInTypeAliasExpansion.fir.kt
new file mode 100644
index 00000000000..1602af910b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/illegalTypeInTypeAliasExpansion.fir.kt
@@ -0,0 +1,12 @@
+typealias A<T> = Array<T>
+typealias AA<T> = A<A<T>>
+
+typealias AN = A<Nothing>
+
+typealias AAN = AA<Nothing>
+
+typealias AAN2 = A<A<Nothing>>
+
+typealias First<X, Y> = List<X>
+typealias UnusedAN1 = First<Int, Array<Nothing>>
+typealias UnusedAN2 = First<Int, A<Nothing>> // TODO
diff --git a/compiler/testData/diagnostics/tests/typealias/import.fir.kt b/compiler/testData/diagnostics/tests/typealias/import.fir.kt
new file mode 100644
index 00000000000..d370c3d0978
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/import.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+// FILE: file1.kt
+package package1
+
+typealias S = String
+
+// FILE: file2.kt
+package package2
+
+typealias I = Int
+
+class Outer {
+    typealias A = Any
+}
+
+// FILE: test.kt
+package package3
+
+import package1.*
+import package2.I
+import package2.Outer.A
+
+val testS: S = ""
+val testI: I = 42
+val testA: A = Any()
diff --git a/compiler/testData/diagnostics/tests/typealias/importForTypealiasObject.fir.kt b/compiler/testData/diagnostics/tests/typealias/importForTypealiasObject.fir.kt
new file mode 100644
index 00000000000..a02955adc61
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/importForTypealiasObject.fir.kt
@@ -0,0 +1,18 @@
+// FILE: 1.kt
+package something
+
+object N
+
+class WC {
+    companion object
+}
+
+typealias T = N
+typealias TWC = WC
+
+// FILE: 2.kt
+import something.T
+import something.TWC
+
+val test1 = T.hashCode()
+val test2 = TWC.hashCode()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/importFromTypeAliasObject.fir.kt b/compiler/testData/diagnostics/tests/typealias/importFromTypeAliasObject.fir.kt
new file mode 100644
index 00000000000..9486785b750
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/importFromTypeAliasObject.fir.kt
@@ -0,0 +1,15 @@
+// FILE: 1.kt
+package bar
+
+typealias HostAlias = Host
+
+object Host {
+    fun foo() {}
+}
+
+// FILE: 2.kt
+import bar.HostAlias.foo
+
+fun test() {
+    foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/importMemberFromJavaViaAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/importMemberFromJavaViaAlias.fir.kt
new file mode 100644
index 00000000000..c07a996b728
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/importMemberFromJavaViaAlias.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_JAVAC
+
+// FILE: test/jv/JavaSample.java
+
+package test.jv;
+
+public class JavaSample {
+    public static void member() {}
+}
+
+// FILE: foo.kt
+
+package test.kot
+
+typealias JavaAlias = test.jv.JavaSample
+
+// FILE: test.kt
+
+import test.kot.JavaAlias
+import test.kot.JavaAlias.member
+
+fun foo(
+    sample: JavaSample,
+    alias: JavaAlias
+) {
+    member()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/inGenerics.fir.kt b/compiler/testData/diagnostics/tests/typealias/inGenerics.fir.kt
new file mode 100644
index 00000000000..567455e61df
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/inGenerics.fir.kt
@@ -0,0 +1,12 @@
+typealias MyString = String
+
+class Container<T>(val x: T)
+
+typealias MyStringContainer = Container<MyString?>
+
+val ms: MyString = "MyString"
+
+val msn: MyString? = null
+
+val msc: MyStringContainer = Container(ms)
+val msc1 = <!INAPPLICABLE_CANDIDATE!>MyStringContainer<!>(null)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/inSupertypesList.fir.kt b/compiler/testData/diagnostics/tests/typealias/inSupertypesList.fir.kt
new file mode 100644
index 00000000000..728ecb7ff5a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/inSupertypesList.fir.kt
@@ -0,0 +1,6 @@
+interface IBase
+
+typealias B = IBase
+
+class Test1 : B
+class Test2 : IBase, B
diff --git a/compiler/testData/diagnostics/tests/typealias/inheritedNestedTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/inheritedNestedTypeAlias.fir.kt
new file mode 100644
index 00000000000..d0e84053c88
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/inheritedNestedTypeAlias.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+interface ICell<T> {
+    val x: T
+}
+
+class Cell<T>(override val x: T): ICell<T>
+
+open class Base<T> {
+    typealias CT = Cell<T>
+    inner class InnerCell(override val x: T): ICell<T>
+}
+
+class Derived : Base<Int>() {
+    val x1: InnerCell = InnerCell(42)
+    val x2: Base<Int>.InnerCell = InnerCell(42)
+
+    val test1: CT = Cell(42)
+    val test2: Base<Int>.CT = Cell(42)
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/inhreritedTypeAliasQualifiedByDerivedClass.fir.kt b/compiler/testData/diagnostics/tests/typealias/inhreritedTypeAliasQualifiedByDerivedClass.fir.kt
new file mode 100644
index 00000000000..3007b87c660
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/inhreritedTypeAliasQualifiedByDerivedClass.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+open class Base {
+    typealias Nested = String
+}
+
+class Derived : Base()
+
+fun test(x: Derived.Nested) = x
+
+fun Base.testWithImplicitReceiver(x: Nested) {
+    val y: Nested = x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/innerClassTypeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/innerClassTypeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..3f044a11226
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/innerClassTypeAliasConstructor.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+class Outer {
+    inner class Inner
+}
+
+typealias OI = Outer.Inner
+
+fun test1(x: Outer) = x.<!UNRESOLVED_REFERENCE!>OI<!>()
+
+
+class Generic<T> {
+    inner class Inner
+}
+
+typealias GI<T> = Generic<T>.Inner
+typealias GIntI = Generic<Int>.Inner
+
+fun test2(x: Generic<Int>) = x.<!UNRESOLVED_REFERENCE!>GI<!>()
+fun <T> test3(x: Generic<T>) = x.<!UNRESOLVED_REFERENCE!>GI<!>()
+fun <T> test4(x: Generic<List<T>>) = x.<!UNRESOLVED_REFERENCE!>GI<!>()
+fun <T> test5(x: Generic<T>) = x.<!UNRESOLVED_REFERENCE!>GIntI<!>()
+fun Generic<Int>.test6() = GIntI()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/innerClassTypeAliasConstructorInSupertypes.fir.kt b/compiler/testData/diagnostics/tests/typealias/innerClassTypeAliasConstructorInSupertypes.fir.kt
new file mode 100644
index 00000000000..22e8b76378c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/innerClassTypeAliasConstructorInSupertypes.fir.kt
@@ -0,0 +1,40 @@
+// !WITH_NEW_INFERENCE
+package test
+
+typealias OI = Outer.Inner
+
+class Outer {
+    open inner class Inner
+
+    inner class Test : OI()
+}
+
+
+typealias GI<T> = Generic<T>.Inner
+typealias GIInt = Generic<Int>.Inner
+typealias GIStar = Generic<*>.Inner
+typealias GG<T1, T2> = Generic<T1>.Generic<T2>
+typealias GIntG<T2> = Generic<Int>.Generic<T2>
+typealias GGInt<T1> = Generic<T1>.Generic<Int>
+
+class Generic<T1> {
+    open inner class Inner
+    open inner class Generic<T2>
+
+    inner class Test1 : GI<T1>()
+    inner class Test2 : GIInt()
+    inner class Test3 : GIStar()
+    inner class Test3a : test.Generic<*>.Inner()
+
+    inner class Test4<T2> : GG<T1, T2>()
+    inner class Test5 : GG<T1, Int>()
+    inner class Test6 : GG<Int, T1>()
+    inner class Test7 : GG<Int, Int>()
+    inner class Test8 : GIntG<Int>()
+    inner class Test9 : GGInt<Int>()
+    inner class Test10 : GGInt<T1>()
+
+    inner class Test11 : GG<T1, Int> {
+        constructor() : super()
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/innerTypeAliasAsType.fir.kt b/compiler/testData/diagnostics/tests/typealias/innerTypeAliasAsType.fir.kt
new file mode 100644
index 00000000000..38b340f6a24
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/innerTypeAliasAsType.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class Outer<T> {
+    class Nested
+    class GenericNested<TT>
+    inner class Inner
+    inner class GenericInner<TT>
+
+    typealias NestedAlias = Nested
+    typealias GenericNestedAlias<TT> = GenericNested<TT>
+    typealias InnerAlias = Inner
+    typealias GenericInnerAlias<TT> = GenericInner<TT>
+
+    fun test1(x: NestedAlias) = x
+    fun test2(x: GenericNestedAlias<Int>) = x
+    fun <T> test3(x: GenericNestedAlias<T>) = x
+    fun test4(x: InnerAlias) = x
+    fun test5(x: GenericInnerAlias<Int>) = x
+    fun <T> test6(x: GenericInnerAlias<T>) = x
+}
+fun test1(x: Outer<Int>.NestedAlias) = x
+fun <T> test2(x: Outer<T>.NestedAlias) = x
+fun test3(x: Outer.NestedAlias) = x
+fun test4(x: Outer<Int>.GenericNestedAlias<Int>) = x
+fun <T> test5(x: Outer<T>.GenericNestedAlias<Int>) = x
+fun <T> test6(x: Outer<Int>.GenericNestedAlias<T>) = x
+fun test7(x: Outer.GenericNestedAlias<Int>) = x
+fun <T> test8(x: Outer.GenericNestedAlias<T>) = x
+fun test9(x: Outer.InnerAlias) = x
+fun test10(x: Outer<Int>.InnerAlias) = x
+fun <T> test11(x: Outer<T>.InnerAlias) = x
+fun test12(x: Outer.GenericInnerAlias<Int>) = x
+fun test13(x: Outer<Int>.GenericInnerAlias<Int>) = x
+fun <T> test14(x: Outer<T>.GenericInnerAlias<Int>) = x
diff --git a/compiler/testData/diagnostics/tests/typealias/innerTypeAliasAsType2.fir.kt b/compiler/testData/diagnostics/tests/typealias/innerTypeAliasAsType2.fir.kt
new file mode 100644
index 00000000000..f1a2018e98d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/innerTypeAliasAsType2.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class C<T> {
+    inner class D
+
+    typealias DA = D
+    typealias SDA = C<Int>.D
+    typealias TSDA = C<T>.D
+    typealias TC = C<T>
+    typealias SSDA = C<*>.D
+    typealias SSC = C<*>
+}
+
+fun test1(x: C<Int>.DA) = x
+fun test2(x: C.SDA) = x
+fun test3(x: C<Int>.TSDA) = x
+fun test4(x: C<Int>.TC) = x
+
+fun test5(x: C<*>.DA) = x
+fun test6(x: C<*>.TSDA) = x
+fun test7(x: C<*>.TC) = x
+
+fun test8(x: C.SSDA) = x
+fun test9(x: C.SSC) = x
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/innerTypeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/innerTypeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..f2e054d434f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/innerTypeAliasConstructor.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class Pair<X, Y>(val x: X, val y: Y)
+
+class C<T> {
+    typealias P = Pair<T, T>
+    typealias P1<X> = Pair<X, T>
+    typealias P2<Y> = Pair<T, Y>
+}
+
+// C<...>.P[<...>]() syntax doesn't work due to the way qualified expressions are resolved now.
+// This restriction can be removed later.
+val test0 = C<Int>.<!UNRESOLVED_REFERENCE!>P<!>(1, 1)
+val test1 = C<Int>.<!UNRESOLVED_REFERENCE!>P1<!><String>("", 1)
+val test2 = C<Int>.<!UNRESOLVED_REFERENCE!>P2<!><String>(1, "")
+val test3 = C<Int>.<!UNRESOLVED_REFERENCE!>P1<!>("", 1)
+val test4 = C<Int>.<!UNRESOLVED_REFERENCE!>P2<!>(1, "")
+
+// C.P() syntax could work if we add captured type parameters as type variables in a constraint system for corresponding call.
+// However, this should be consistent with inner classes capturing type parameters.
+val test5 = C.<!UNRESOLVED_REFERENCE!>P<!>(1, 1)
+val test6 = C.<!UNRESOLVED_REFERENCE!>P1<!>("", 1)
+val test7 = C.<!UNRESOLVED_REFERENCE!>P2<!>(1, "")
diff --git a/compiler/testData/diagnostics/tests/typealias/isAsWithTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/isAsWithTypeAlias.fir.kt
new file mode 100644
index 00000000000..bf998f4817c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/isAsWithTypeAlias.fir.kt
@@ -0,0 +1,5 @@
+typealias S = String
+
+fun test1(x: Any) = x is S
+fun test2(x: Any) = x as S
+fun test3(x: Any) = x as? S
diff --git a/compiler/testData/diagnostics/tests/typealias/javaStaticMembersViaTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/javaStaticMembersViaTypeAlias.fir.kt
new file mode 100644
index 00000000000..df25925e618
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/javaStaticMembersViaTypeAlias.fir.kt
@@ -0,0 +1,46 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: JTest.java
+public class JTest {
+    public static String foo() { return ""; }
+    public static class Nested {}
+}
+
+// FILE: JDerived.java
+public class JDerived extends JTest {
+}
+
+// FILE: test.kt
+class KTest {
+    class Nested
+    inner class Inner
+}
+
+interface ITest {
+    class Nested
+}
+
+typealias JT = JTest
+typealias JD = JDerived
+typealias KT = KTest
+typealias IT = ITest
+
+// Referencing Java class static members via type alias should be ok
+val testFoo: String = JT.<!UNRESOLVED_REFERENCE!>foo<!>()
+val seeAlsoFoo: String = JTest.foo()
+// Referencing base Java class static members via type alias for derived Java class should be ok
+val testDerivedFoo: String = JD.<!UNRESOLVED_REFERENCE!>foo<!>()
+val seeAlsoDerivedFoo: String = JDerived.foo()
+
+// Referencing nested classes via type alias should be prohibited
+// (in type position and in expression position)
+val testNested1: JT.Nested = JT.<!UNRESOLVED_REFERENCE!>Nested<!>()
+val testNested2: KT.Nested = KT.Nested()
+val testNested3: IT.Nested = IT.Nested()
+val testInner1: JT.Inner = JT.<!UNRESOLVED_REFERENCE!>Inner<!>()
+val testInner2: KT.Inner = KT.<!UNRESOLVED_REFERENCE!>Inner<!>()
+fun testNestedAsTypeArgument1(x: List<JT.Nested>) {}
+fun testNestedAsTypeArgument2(x: List<KT.Nested>) {}
+fun testNestedAsTypeArgument3(x: List<IT.Nested>) {}
+fun testInnerAsTypeArgument1(x: List<JT.Inner>) {}
+fun testInnerAsTypeArgument2(x: List<KT.Inner>) {}
+
diff --git a/compiler/testData/diagnostics/tests/typealias/kt14498.fir.kt b/compiler/testData/diagnostics/tests/typealias/kt14498.fir.kt
new file mode 100644
index 00000000000..37df74eb372
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/kt14498.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_TYPEALIAS_PARAMETER
+
+interface I1<S>
+interface Out<out T>
+interface InvOut<T1, out T2>
+
+typealias A1<S> = I1<S>
+typealias A2<T, S> = I1<S>
+typealias AOut<T> = Out<T>
+typealias AInvOut<T1, T2> = InvOut<T1, T2>
+typealias AInvOutTT<T> = AInvOut<T, T>
+
+class Test1<out S> : A1<S>
+class Test2<out S> : A2<Any, S>
+class Test3<out S> : AOut<S>
+class Test4<out S> : AInvOut<S, S>
+class Test5<out S> : AInvOutTT<S>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/kt14498a.fir.kt b/compiler/testData/diagnostics/tests/typealias/kt14498a.fir.kt
new file mode 100644
index 00000000000..9525f219a2f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/kt14498a.fir.kt
@@ -0,0 +1,11 @@
+interface Out<out R>
+interface Inv<E>
+typealias A1<E> = Out<Out<E>>
+typealias A2<E> = Out<Out<E>>
+typealias A3<E> = Inv<Out<E>>
+typealias A4<E> = Out<Inv<E>>
+
+interface Q1<out S> : Out<A1<S>>
+interface Q2<out S> : Out<A2<S>>
+interface Q3<out S> : Out<A3<S>>
+interface Q4<out S> : Out<A4<S>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/kt14518.fir.kt b/compiler/testData/diagnostics/tests/typealias/kt14518.fir.kt
new file mode 100644
index 00000000000..8af18fe0e40
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/kt14518.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class OuterClass<T1> {
+    class NestedClass<T2>
+    typealias NestedType<T> = NestedClass<T>
+}
+
+typealias ON1<T1, T2> = OuterClass<T1>.NestedClass<T2>
+typealias ON2<T1, T2> = OuterClass<T1>.NestedType<T2>
+typealias ON3<T2> = OuterClass.NestedType<T2>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/kt14641.fir.kt b/compiler/testData/diagnostics/tests/typealias/kt14641.fir.kt
new file mode 100644
index 00000000000..d4014f9c2fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/kt14641.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class A {
+    public inner class B { }
+    public typealias BAlias = B
+}
+
+fun f() {
+    val a = A()
+    a.<!UNRESOLVED_REFERENCE!>BAlias<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/kt15734.fir.kt b/compiler/testData/diagnostics/tests/typealias/kt15734.fir.kt
new file mode 100644
index 00000000000..f35a9e1befc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/kt15734.fir.kt
@@ -0,0 +1,19 @@
+@Target(AnnotationTarget.TYPE)
+annotation class Ann
+
+typealias TString = String
+
+typealias TNString = TString?
+
+typealias TNAString = @Ann TString?
+
+val test1: TNString = TODO()
+val test2: TNAString = TODO()
+val test3: List<TNString> = TODO()
+val test4: List<TNAString> = TODO()
+val test5: List<TNString?> = TODO()
+val test6: () -> List<TNString> = TODO()
+
+fun test(x: TNString) {
+    x.hashCode()
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/kt19601.fir.kt b/compiler/testData/diagnostics/tests/typealias/kt19601.fir.kt
new file mode 100644
index 00000000000..324ac3752e4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/kt19601.fir.kt
@@ -0,0 +1,11 @@
+interface Order<T>
+
+typealias Ord<T> = Order<T>
+
+class Test1<T1 : Ord<T1>>
+
+interface Num<T : Number>
+
+typealias N<T> = Num<T>
+
+class Test2<T : N<String>>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/localTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/localTypeAlias.fir.kt
new file mode 100644
index 00000000000..a7c55d93331
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/localTypeAlias.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+fun <T> emptyList(): List<T> = null!!
+
+fun <T> foo() {
+    typealias LT = List<T>
+
+    val a: LT = emptyList()
+
+    fun localFun(): LT {
+        typealias LLT = List<T>
+
+        val b: LLT = a
+
+        return b
+    }
+
+    localFun()
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/localTypeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/localTypeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..9ef9044cf81
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/localTypeAliasConstructor.fir.kt
@@ -0,0 +1,11 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class Cell<TC>(val x: TC)
+
+fun <T> id(x: T): T {
+    typealias C = Cell<T>
+    class Local(val cell: C)
+    val cx = <!UNRESOLVED_REFERENCE!>C<!>(x)
+    val c: C = Local(cx).cell
+    return c.<!UNRESOLVED_REFERENCE!>x<!>
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/localTypeAliasModifiers.fir.kt b/compiler/testData/diagnostics/tests/typealias/localTypeAliasModifiers.fir.kt
new file mode 100644
index 00000000000..c6bc19100cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/localTypeAliasModifiers.fir.kt
@@ -0,0 +1,5 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+fun outer() {
+    companion typealias TestLocal = Any
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/localTypeAliasRecursive.fir.kt b/compiler/testData/diagnostics/tests/typealias/localTypeAliasRecursive.fir.kt
new file mode 100644
index 00000000000..571a38bf315
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/localTypeAliasRecursive.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+fun outer() {
+    typealias Test1 = Test1
+    typealias Test2 = List<Test2>
+    typealias Test3<T> = List<Test3<T>>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/methodReference.fir.kt b/compiler/testData/diagnostics/tests/typealias/methodReference.fir.kt
new file mode 100644
index 00000000000..c0914863e45
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/methodReference.fir.kt
@@ -0,0 +1,7 @@
+class C {
+    fun foo() {}
+}
+
+typealias CA = C
+
+val cf = CA::foo
diff --git a/compiler/testData/diagnostics/tests/typealias/nested.fir.kt b/compiler/testData/diagnostics/tests/typealias/nested.fir.kt
new file mode 100644
index 00000000000..77a8316109e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/nested.fir.kt
@@ -0,0 +1,24 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class Pair<T1, T2>(val x1: T1, val x2: T2)
+
+class C {
+    typealias P2 = Pair<Int, Int>
+
+    fun p() = <!UNRESOLVED_REFERENCE!>P2<!>(1, 1)
+    fun first(p: P2) = p.<!UNRESOLVED_REFERENCE!>x1<!>
+    fun second(p: P2) = p.<!UNRESOLVED_REFERENCE!>x2<!>
+}
+
+val p1 = Pair(1, 1)
+
+val test1: Int = C().first(p1)
+val test2: Int = C().second(p1)
+
+fun C.testExtFun1(x: C.P2) = x
+
+fun C.testExtFun2(): C.P2 {
+    val x: C.P2 = p()
+    val y = C.<!UNRESOLVED_REFERENCE!>P2<!>(1, 1)
+    return x
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/nestedCapturingTypeParameters.fir.kt b/compiler/testData/diagnostics/tests/typealias/nestedCapturingTypeParameters.fir.kt
new file mode 100644
index 00000000000..08e34472f34
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/nestedCapturingTypeParameters.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class Pair<T1, T2>(val x1: T1, val x2: T2)
+
+class C<T> {
+    typealias P2 = Pair<T, T>
+    typealias PT2<T2> = Pair<T, T2>
+
+    fun first(p: P2) = p.<!UNRESOLVED_REFERENCE!>x1<!>
+    fun second(p: P2) = p.<!UNRESOLVED_REFERENCE!>x2<!>
+
+    fun <T2> first2(p: PT2<T2>) = p.<!UNRESOLVED_REFERENCE!>x1<!>
+    fun <T2> second2(p: PT2<T2>) = p.<!UNRESOLVED_REFERENCE!>x2<!>
+}
+
+val p1 = Pair(1, 1)
+val p2 = Pair(1, "")
+
+val test1: Int = C<Int>().first(p1)
+val test2: Int = C<Int>().second(p1)
+
+val test3: Int = C<Int>().first2(p2)
+val test4: String = C<Int>().second2(p2)
diff --git a/compiler/testData/diagnostics/tests/typealias/nestedSubstituted.fir.kt b/compiler/testData/diagnostics/tests/typealias/nestedSubstituted.fir.kt
new file mode 100644
index 00000000000..e5ec2fb2f50
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/nestedSubstituted.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+class Pair<T1, T2>(val x1: T1, val x2: T2)
+
+class C<T> {
+    typealias P2 = Pair<T, Int>
+}
+
+val p1: C<String>.P2 = Pair("", 1)
diff --git a/compiler/testData/diagnostics/tests/typealias/noApproximationInTypeAliasArgumentSubstitution.fir.kt b/compiler/testData/diagnostics/tests/typealias/noApproximationInTypeAliasArgumentSubstitution.fir.kt
new file mode 100644
index 00000000000..6e62fc11653
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/noApproximationInTypeAliasArgumentSubstitution.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+typealias Array2D<T> = Array<Array<T>>
+
+fun foo1(a: Array2D<out Number>) = a
+
+fun bar1(a: Array2D<Int>) =
+        <!INAPPLICABLE_CANDIDATE!>foo1<!>(a)
+
+
+typealias TMap<T> = Map<T, T>
+
+fun <T> foo2(m: TMap<T>) = m
+
+fun bar2(m: TMap<*>) =
+        foo2(m)
diff --git a/compiler/testData/diagnostics/tests/typealias/noRHS.fir.kt b/compiler/testData/diagnostics/tests/typealias/noRHS.fir.kt
new file mode 100644
index 00000000000..f2598266905
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/noRHS.fir.kt
@@ -0,0 +1,6 @@
+typealias<!SYNTAX!><!>
+
+<!SYNTAX!><!>typealias A1<!SYNTAX!><!>
+
+<!SYNTAX!><!>typealias A2 =
+<!SYNTAX!><!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/parameterRestrictions.fir.kt b/compiler/testData/diagnostics/tests/typealias/parameterRestrictions.fir.kt
new file mode 100644
index 00000000000..8515a4b3cf4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/parameterRestrictions.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_TYPEALIAS_PARAMETER
+
+typealias WithVariance<in X, out Y> = Int
+typealias WithBounds1<T : T> = Int
+typealias WithBounds2<X : Y, Y : X> = Int
+
+typealias WithBounds3<X> <!SYNTAX!>where X : Any<!> = Int
+
+val x: WithVariance<Int, Int> = 0
diff --git a/compiler/testData/diagnostics/tests/typealias/parameterSubstitution.fir.kt b/compiler/testData/diagnostics/tests/typealias/parameterSubstitution.fir.kt
new file mode 100644
index 00000000000..35fd6a5dd58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/parameterSubstitution.fir.kt
@@ -0,0 +1,8 @@
+class C<T>
+
+typealias CA<T> = C<T>
+
+val ca1: CA<Int> = C<Int>()
+val ca2: CA<CA<Int>> = C<C<Int>>()
+val ca3: CA<C<Int>> = C<C<Int>>()
+val ca4: CA<Int?> = C<Int?>()
diff --git a/compiler/testData/diagnostics/tests/typealias/privateInFile.fir.kt b/compiler/testData/diagnostics/tests/typealias/privateInFile.fir.kt
new file mode 100644
index 00000000000..c76aa214c7e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/privateInFile.fir.kt
@@ -0,0 +1,22 @@
+// FILE: file1.kt
+private class C {
+    companion object
+}
+
+private typealias TA = C
+
+private val test1: C = <!INAPPLICABLE_CANDIDATE!>C<!>()
+private val test1co: C.Companion = C
+
+private val test2: TA = <!INAPPLICABLE_CANDIDATE!>TA<!>()
+private val test2co = TA
+
+// FILE: file2.kt
+private val test1: C = C()
+private val test1co: C.Companion = C
+
+private val test2: TA = <!INAPPLICABLE_CANDIDATE!>TA<!>()
+private val test2co = TA
+
+private class C
+private typealias TA = Int
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/projectionsInTypeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/projectionsInTypeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..3be68c3e5dc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/projectionsInTypeAliasConstructor.fir.kt
@@ -0,0 +1,6 @@
+class In<in T>(val x: Any)
+
+typealias InAlias<T> = In<T>
+
+val test1 = In<out String>("")
+val test2 = InAlias<out String>("")
diff --git a/compiler/testData/diagnostics/tests/typealias/recursive.fir.kt b/compiler/testData/diagnostics/tests/typealias/recursive.fir.kt
new file mode 100644
index 00000000000..ffa482edf53
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/recursive.fir.kt
@@ -0,0 +1,11 @@
+typealias R = <!OTHER_ERROR!>R<!>
+
+typealias L = List<L>
+
+typealias A = B
+typealias B = <!OTHER_ERROR!>A<!>
+
+typealias F1 = (Int) -> F2
+typealias F2 = (F1) -> Int
+
+val x: A = TODO()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/returnTypeNothingShouldBeSpecifiedExplicitly.fir.kt b/compiler/testData/diagnostics/tests/typealias/returnTypeNothingShouldBeSpecifiedExplicitly.fir.kt
new file mode 100644
index 00000000000..d5da819532c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/returnTypeNothingShouldBeSpecifiedExplicitly.fir.kt
@@ -0,0 +1,5 @@
+typealias N = Nothing
+
+fun testFun(): N = null!!
+val testVal: N = null!!
+val testValWithGetter: N get() = null!!
diff --git a/compiler/testData/diagnostics/tests/typealias/simpleTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/simpleTypeAlias.fir.kt
new file mode 100644
index 00000000000..65b7bc9ff00
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/simpleTypeAlias.fir.kt
@@ -0,0 +1,8 @@
+typealias S = String
+typealias SS = S
+typealias SSS = SS
+
+val s1: SSS = ""
+val s2: SSS? = null
+val s3: List<SSS>? = null
+val s4: List<List<SSS>?>? = null
diff --git a/compiler/testData/diagnostics/tests/typealias/starImportOnTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/starImportOnTypeAlias.fir.kt
new file mode 100644
index 00000000000..6634ae21081
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/starImportOnTypeAlias.fir.kt
@@ -0,0 +1,30 @@
+// FILE: foo.kt
+
+// FILE: foo.kt
+
+package test
+
+typealias ClassAlias = ClassSample
+typealias ObjectAlias = ObjectSample
+typealias EnumAlias = EnumSample
+
+class ClassSample
+
+object ObjectSample
+
+enum class EnumSample {
+    Entry;
+}
+
+// FILE: bar.kt
+
+import test.ClassAlias.*
+import test.ObjectAlias.*
+import test.EnumAlias.*
+import test.EnumAlias
+
+
+fun bar() {
+    <!UNRESOLVED_REFERENCE!>Entry<!>
+    EnumAlias.<!UNRESOLVED_REFERENCE!>Entry<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/starProjection.fir.kt b/compiler/testData/diagnostics/tests/typealias/starProjection.fir.kt
new file mode 100644
index 00000000000..2b0c3acbeed
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/starProjection.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+typealias A<T> = Map<T, T>
+typealias B = A<*>
+
+fun check(x: B) = x
+
+fun test1(x: Map<Int, Int>) = check(x)
+
+fun test2(x: Map<String, Int>) = check(x)
+
+fun test3(x: Map<Int, String>) = check(x).size
+
+fun test4(x: Map<Int, String>) = check(x)["42"]
+
+fun test5(x: Map<Int, String>) = check(x)[42]
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/starProjectionInTypeAliasArgument.fir.kt b/compiler/testData/diagnostics/tests/typealias/starProjectionInTypeAliasArgument.fir.kt
new file mode 100644
index 00000000000..4f98fe9a121
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/starProjectionInTypeAliasArgument.fir.kt
@@ -0,0 +1,6 @@
+class NumCharSeq<N : Number, M : CharSequence>(val n: N, val m: M)
+
+typealias Test<X, Y> = NumCharSeq<X, Y>
+
+fun getN(t: Test<*, *>) = t.n
+fun getM(t: Test<*, *>) = t.m
diff --git a/compiler/testData/diagnostics/tests/typealias/substitutionVariance.fir.kt b/compiler/testData/diagnostics/tests/typealias/substitutionVariance.fir.kt
new file mode 100644
index 00000000000..bb31c55e0fc
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/substitutionVariance.fir.kt
@@ -0,0 +1,67 @@
+// NI_EXPECTED_FILE
+
+class In<in T>
+class Out<out T>
+class Inv<T>
+
+typealias In1<T> = In<T>
+typealias In2<T> = In<in T>
+typealias In3<T> = In<out T>
+typealias In4<T> = In<*>
+
+typealias Out1<T> = Out<T>
+typealias Out2<T> = Out<in T>
+typealias Out3<T> = Out<out T>
+typealias Out4<T> = Out<*>
+
+typealias Inv1<T> = Inv<T>
+typealias Inv2<T> = Inv<in T>
+typealias Inv3<T> = Inv<out T>
+typealias Inv4<T> = Inv<*>
+
+val inv1: Inv1<Int> = Inv<Int>()
+
+fun inInv_Inv(x: In1<Int>) = x
+fun inInv_In(x: In1<in Int>) = x
+fun inInv_Out(x: In1<out Int>) = x
+fun inInv_Star(x: In1<*>) = x
+
+fun inIn_Inv(x: In2<Int>) = x
+fun inIn_In(x: In2<in Int>) = x
+fun inIn_Out(x: In2<out Int>) = x
+fun inIn_Star(x: In2<*>) = x
+
+fun inOut_Inv(x: In3<Int>) = x
+fun inOut_In(x: In3<in Int>) = x
+fun inOut_Out(x: In3<out Int>) = x
+fun inOut_Star(x: In3<*>) = x
+
+fun outInv_Inv(x: Out1<Int>) = x
+fun outInv_In(x: Out1<in Int>) = x
+fun outInv_Out(x: Out1<out Int>) = x
+fun outInv_Star(x: Out1<*>) = x
+
+fun outIn_Inv(x: Out2<Int>) = x
+fun outIn_In(x: Out2<in Int>) = x
+fun outIn_Out(x: Out2<out Int>) = x
+fun outIn_Star(x: Out2<*>) = x
+
+fun outOut_Inv(x: Out3<Int>) = x
+fun outOut_In(x: Out3<in Int>) = x
+fun outOut_Out(x: Out3<out Int>) = x
+fun outOut_Star(x: Out3<*>) = x
+
+fun invInv_Inv(x: Inv1<Int>) = x
+fun invInv_In(x: Inv1<in Int>) = x
+fun invInv_Out(x: Inv1<out Int>) = x
+fun invInv_Star(x: Inv1<*>) = x
+
+fun invIn_Inv(x: Inv2<Int>) = x
+fun invIn_In(x: Inv2<in Int>) = x
+fun invIn_Out(x: Inv2<out Int>) = x
+fun invIn_Star(x: Inv2<*>) = x
+
+fun invOut_Inv(x: Inv3<Int>) = x
+fun invOut_In(x: Inv3<in Int>) = x
+fun invOut_Out(x: Inv3<out Int>) = x
+fun invOut_Star(x: Inv3<*>) = x
diff --git a/compiler/testData/diagnostics/tests/typealias/throwJLException.fir.kt b/compiler/testData/diagnostics/tests/typealias/throwJLException.fir.kt
new file mode 100644
index 00000000000..ad99d935b42
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/throwJLException.fir.kt
@@ -0,0 +1,7 @@
+// +JDK
+
+typealias Exn = java.lang.Exception
+
+fun test() {
+    throw Exn
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/topLevelTypeAliasesOnly.fir.kt b/compiler/testData/diagnostics/tests/typealias/topLevelTypeAliasesOnly.fir.kt
new file mode 100644
index 00000000000..8c79e33dda3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/topLevelTypeAliasesOnly.fir.kt
@@ -0,0 +1,19 @@
+typealias TopLevel = Any
+
+interface A {
+    typealias Nested = Any
+}
+
+class C {
+    typealias Nested = Any
+    class D {
+        typealias Nested = Any
+        fun foo() {
+            typealias LocalInMember = Any
+        }
+    }
+}
+
+fun foo() {
+    typealias Local = Any
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasArgumentsInCompanionObject.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasArgumentsInCompanionObject.fir.kt
new file mode 100644
index 00000000000..2e44c513075
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasArgumentsInCompanionObject.fir.kt
@@ -0,0 +1,10 @@
+class C<T1, T2> {
+    companion object {
+        val OK = "OK"
+    }
+}
+
+typealias C2<T> = C<T, T>
+
+val test1: String = C2<String>.<!UNRESOLVED_REFERENCE!>OK<!>
+val test2: String = C2.<!UNRESOLVED_REFERENCE!>OK<!>
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasArgumentsInConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasArgumentsInConstructor.fir.kt
new file mode 100644
index 00000000000..8945b180940
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasArgumentsInConstructor.fir.kt
@@ -0,0 +1,11 @@
+class Pair<T1, T2>(val x1: T1, val x2: T2)
+
+typealias P2<T> = Pair<T, T>
+
+val test1: Pair<String, String> = P2<String>("", "")
+val test1x1: String = test1.x1
+val test1x2: String = test1.x2
+
+val test2: P2<String> = P2<String>("", "")
+val test2x1: String = test2.x1
+val test2x2: String = test2.x2
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasAsBareType.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasAsBareType.fir.kt
new file mode 100644
index 00000000000..58a8a49211c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasAsBareType.fir.kt
@@ -0,0 +1,35 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+typealias L<T> = List<T>
+typealias NL<T> = List<T>?
+typealias LStar<T> = List<*>
+typealias MyList<T, X> = List<X>
+
+fun testL1(x: Collection<Any>) = x is L
+fun testL2(x: Collection<Int>): List<Int> = x as L
+fun testL3(x: Collection<Int>?): List<Int>? = x as L?
+fun testL4(x: Collection<Int>?): List<Int>? = x as? L
+
+fun testNL1(x: Collection<Int>?): Boolean = x is NL
+fun testNL2(x: Collection<Int>?): List<Int>? = x as NL
+fun testNL3(x: Collection<Int>?): List<Int>? = x as NL?
+
+fun testLStar(x: Collection<Int>): List<Int> = x as LStar
+fun testMyList(x: Collection<Int>): List<Int> = x as MyList
+
+typealias MMTT<T> = MutableMap<T, T>
+typealias Dictionary<T> = MutableMap<String, T>
+typealias WriteableMap<K, V> = MutableMap<in K, V>
+typealias ReadableList<T> = MutableList<out T>
+
+fun testWrong1(x: Map<Any, Any>) = x is MMTT
+fun testWrong2(x: Map<Any, Any>) = x is Dictionary
+fun testWrong3(x: Map<Any, Any>) = x is WriteableMap
+fun testWrong4(x: List<Any>) = x is ReadableList
+
+fun <T> testLocal(x: Any) {
+    class C
+    typealias CA = C
+    if (x is C) {}
+    if (x is CA) {}
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasAsQualifier.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasAsQualifier.fir.kt
new file mode 100644
index 00000000000..1894f09620f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasAsQualifier.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+// NI_EXPECTED_FILE
+
+class C {
+    typealias Self = C
+    class Nested {
+        class N2
+        typealias Root = C
+    }
+    companion object X {
+        val ok = "OK"
+        class InCompanion
+    }
+}
+
+val c = C.Self.<!UNRESOLVED_REFERENCE!>Self<!>()
+val n = C.Self.Nested()
+val x = C.Self.<!UNRESOLVED_REFERENCE!>X<!>
+val n2 = C.Nested.Root.<!UNRESOLVED_REFERENCE!>Nested<!>.<!UNRESOLVED_REFERENCE!>N2<!>()
+val ic = C.Self.<!UNRESOLVED_REFERENCE!>InCompanion<!>()
+val ok = C.Self.<!UNRESOLVED_REFERENCE!>ok<!>
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasAsSuperQualifier.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasAsSuperQualifier.fir.kt
new file mode 100644
index 00000000000..39534bbba1b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasAsSuperQualifier.fir.kt
@@ -0,0 +1,41 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+open class Base {
+    open fun foo() {}
+}
+
+open class GenericBase<T> {
+    open fun foo() {}
+}
+
+class Unrelated {
+    fun foo() {}
+}
+
+typealias B = Base
+typealias U = Unrelated
+typealias GB<T> = GenericBase<T>
+
+class TestSuperForBase : B() {
+    typealias MyBase = B
+
+    override fun foo() {
+        super<Base>.foo()
+        super<B>.foo()
+        super<MyBase>.<!UNRESOLVED_REFERENCE!>foo<!>()
+        super<U>.foo()
+    }
+}
+
+class TestSuperForGenericBase<T> : GB<T>() {
+    typealias MyBase = GB<T>
+    typealias MyBaseInt = GB<Int>
+
+    override fun foo() {
+        super<GenericBase>.foo()
+        super<GB>.foo()
+        super<MyBase>.<!UNRESOLVED_REFERENCE!>foo<!>()
+        super<MyBaseInt>.<!UNRESOLVED_REFERENCE!>foo<!>() // Type arguments don't matter here
+        super<U>.foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..098cb31bb3b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructor.fir.kt
@@ -0,0 +1,24 @@
+class C(val x: String) {
+    constructor(): this("")
+}
+
+typealias TC = C
+
+val test1: C = TC("")
+val test2: TC = TC("")
+val test3: C = TC()
+val test4: TC = TC()
+
+val test5 = <!INAPPLICABLE_CANDIDATE!>TC<!>("", "")
+
+interface Interface
+typealias TI = Interface
+
+object AnObject
+typealias TO = AnObject
+
+val test6 = <!UNRESOLVED_REFERENCE!>TI<!>()
+val test6a = <!UNRESOLVED_REFERENCE!>Interface<!>()
+
+val test7 = <!INAPPLICABLE_CANDIDATE!>TO<!>()
+val test7a = <!INAPPLICABLE_CANDIDATE!>AnObject<!>()
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorCrazyProjections.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorCrazyProjections.fir.kt
new file mode 100644
index 00000000000..ef5ecb51b5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorCrazyProjections.fir.kt
@@ -0,0 +1,16 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+class Bound<X, Y : X>(val x: X, val y: Y)
+typealias B<X, Y> = Bound<X, Y>
+typealias BOutIn<T> = Bound<out List<T>, in T>
+typealias BInIn<T> = Bound<in List<T>, in T>
+
+fun <T> listOf(): List<T> = null!!
+
+// Unresolved reference is ok here:
+// we can't create a substituted signature for type alias constructor
+// since it has 'out' type projection in 'in' position.
+val test1 = <!UNRESOLVED_REFERENCE!>BOutIn<!>(listOf(), null!!)
+
+val test2 = <!UNRESOLVED_REFERENCE!>BInIn<!>(listOf(), null!!)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForInterface.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForInterface.fir.kt
new file mode 100644
index 00000000000..7696ae222a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForInterface.fir.kt
@@ -0,0 +1,6 @@
+interface IFoo
+
+typealias Test = IFoo
+
+val testAsFunction = <!UNRESOLVED_REFERENCE!>Test<!>()
+val testAsValue = Test
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForProjection.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForProjection.fir.kt
new file mode 100644
index 00000000000..b708007b8f7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForProjection.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+class C<T>
+
+typealias CStar = C<*>
+typealias CIn = C<in Int>
+typealias COut = C<out Int>
+typealias CT<T> = C<T>
+
+val test1 = <!UNRESOLVED_REFERENCE!>CStar<!>()
+val test2 = <!UNRESOLVED_REFERENCE!>CIn<!>()
+val test3 = <!UNRESOLVED_REFERENCE!>COut<!>()
+val test4 = CT<*>()
+val test5 = CT<CT<*>>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForProjectionInSupertypes.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForProjectionInSupertypes.fir.kt
new file mode 100644
index 00000000000..4db0b2a98f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorForProjectionInSupertypes.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+open class C<T>
+
+typealias CStar = C<*>
+typealias CIn = C<in Int>
+typealias COut = C<out Int>
+typealias CT<T> = C<T>
+
+class Test1 : CStar()
+class Test2 : CIn()
+class Test3 : COut()
+
+class Test4 : CStar {
+    constructor() : super()
+}
+
+class Test5 : CT<*>()
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorInSuperCall.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorInSuperCall.fir.kt
new file mode 100644
index 00000000000..71c53d03a77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorInSuperCall.fir.kt
@@ -0,0 +1,14 @@
+open class MyBase protected constructor() {
+    protected constructor(x: Nothing?): this()
+}
+typealias MyAlias = MyBase
+
+class MyDerived1 : <!INAPPLICABLE_CANDIDATE!>MyAlias<!>()
+class MyDerived1a : MyBase()
+
+class MyDerived2 : <!INAPPLICABLE_CANDIDATE!>MyAlias<!>(null)
+class MyDerived2a : MyBase(null)
+
+class MyDerived3 : MyAlias {
+    constructor(x: Nothing?) : <!INAPPLICABLE_CANDIDATE!>super<!>(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorInferenceInSupertypesList.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorInferenceInSupertypesList.fir.kt
new file mode 100644
index 00000000000..a2653eecef4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorInferenceInSupertypesList.fir.kt
@@ -0,0 +1,7 @@
+open class Ref<T>(var x: T)
+
+typealias R<T> = Ref<T>
+
+// Type inference SHOULD NOT work for type alias constructor in supertypes list
+class Test1 : R(0)
+class Test2 : R<Int>(0)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorReturnType.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorReturnType.fir.kt
new file mode 100644
index 00000000000..e6a4d0eae5b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorReturnType.fir.kt
@@ -0,0 +1,18 @@
+class Cell<T>(val x : T)
+class Pair<T1, T2>(val x1: T1, val x2: T2)
+
+typealias CIntA = Cell<Int>
+typealias CA<TA> = Cell<TA>
+typealias PIntIntA = Pair<Int, Int>
+typealias PA<T1A, T2A> = Pair<T1A, T2A>
+typealias P2A<TA> = Pair<TA, TA>
+
+val test1 = CIntA(10)
+val test2 = CA<Int>(10)
+val test3 = CA(10)
+val test4 = PIntIntA(10, 20)
+val test5 = PA<Int, Int>(10, 20)
+val test6 = PA(10, 20)
+val test7 = P2A<Int>(10, 20)
+val test8 = P2A(10, 20)
+
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInference.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInference.fir.kt
new file mode 100644
index 00000000000..ce8525c055c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInference.fir.kt
@@ -0,0 +1,33 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+class Num<Tn : Number>(val x: Tn)
+typealias N<T> = Num<T>
+
+val test0 = N(1)
+val test1 = N("1")
+
+
+class Cons<T>(val head: T, val tail: Cons<T>?)
+typealias C<T> = Cons<T>
+typealias CC<T> = C<C<T>>
+
+val test2 = <!INAPPLICABLE_CANDIDATE!>C<!>(1, 2)
+val test3 = <!INAPPLICABLE_CANDIDATE!>CC<!>(1, 2)
+val test4 = CC(C(1, null), null)
+
+
+class Pair<X, Y>(val x: X, val y: Y)
+typealias PL<T> = Pair<T, List<T>>
+typealias PN<T> = Pair<T, Num<T>>
+
+val test5 = PL(1, null)
+
+
+class Foo<T>(val p: Pair<T, T>)
+typealias F<T> = Foo<T>
+
+fun testProjections1(x: Pair<in Int, out String>) = <!INAPPLICABLE_CANDIDATE!>F<!>(x)
+fun testProjections2(x: Pair<in Int, out Number>) = <!INAPPLICABLE_CANDIDATE!>F<!>(x)
+fun testProjections3(x: Pair<in Number, out Int>) = <!INAPPLICABLE_CANDIDATE!>F<!>(x)
+fun testProjections4(x: Pair<in Int, in Int>) = <!INAPPLICABLE_CANDIDATE!>F<!>(x)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithNestedCalls.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithNestedCalls.fir.kt
new file mode 100644
index 00000000000..7f8a87e86f3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithNestedCalls.fir.kt
@@ -0,0 +1,8 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+class Cons<T : Number>(val head: T, val tail: Cons<T>?)
+typealias C<T> = Cons<T>
+
+val test1 = C(1, C(2, null))
+val test2 = C(1, C("", null))
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithNestedCalls2.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithNestedCalls2.fir.kt
new file mode 100644
index 00000000000..52045873554
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithNestedCalls2.fir.kt
@@ -0,0 +1,41 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+interface Ref<T> {
+    var x: T
+}
+
+class LateInitNumRef<NN: Number>() : Ref<NN> {
+    constructor(x: NN) : this() { this.x = x }
+
+    private var xx: NN? = null
+
+    override var x: NN
+        get() = xx!!
+        set(value) {
+            xx = value
+        }
+}
+
+typealias LateNR<Nt> = LateInitNumRef<Nt>
+
+fun <V, R : Ref<in V>> update(r: R, v: V): R {
+    r.x = v
+    return r
+}
+
+val r1 = update(LateInitNumRef(), 1)
+val r1a = update(LateNR(), 1)
+val r2 = update(LateInitNumRef(1), 1)
+val r2a = update(LateNR(1), 1)
+val r3 = LateInitNumRef(1)
+val r3a = LateNR(1)
+
+fun test() {
+    r1.x = r1.x
+    r1a.x = r1a.x
+    r2.x = r2.x
+    r2a.x = r2a.x
+    r3.x = r3.x
+    r3a.x = r3a.x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithPhantomTypes.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithPhantomTypes.fir.kt
new file mode 100644
index 00000000000..b49ee36fb07
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorTypeArgumentsInferenceWithPhantomTypes.fir.kt
@@ -0,0 +1,17 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+class Foo<A : Number>
+class Bar<B : CharSequence>
+
+class Hr<A, B, C, D>(val a: A, val b: B)
+
+typealias Test<A, B> = Hr<A, B, Foo<A>, Bar<B>>
+
+val test1 = Test(1, "")
+val test2 = Test(1, 2)
+
+
+typealias Bas<T> = Hr<T, T, Foo<T>, Bar<T>>
+
+val test3 = Bas(1, 1)
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorVsFunction.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorVsFunction.fir.kt
new file mode 100644
index 00000000000..f4b3547a87d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorVsFunction.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !CHECK_TYPE
+// FILE: a.kt
+class B(x: String)
+
+typealias A1 = B
+private typealias A2 = B
+private typealias A3 = B
+
+fun A3(x: Any) = "OK"
+
+fun bar() {
+    A3("") checkType { <!UNRESOLVED_REFERENCE!>_<!><B>() }
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorWrongClass.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorWrongClass.fir.kt
new file mode 100644
index 00000000000..554340134b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorWrongClass.fir.kt
@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+abstract class AbstractClass
+typealias Test1 = AbstractClass
+val test1 = Test1()
+val test1a = AbstractClass()
+
+annotation class AnnotationClass
+typealias Test2 = AnnotationClass
+val test2 = Test2()
+val test2a = AnnotationClass()
+
+enum class EnumClass { VALUE1, VALUE2 }
+typealias Test3 = EnumClass
+val test3 = <!INAPPLICABLE_CANDIDATE!>Test3<!>()
+val test3a = <!INAPPLICABLE_CANDIDATE!>EnumClass<!>()
+
+sealed class SealedClass
+typealias Test4 = SealedClass
+val test4 = Test4()
+val test4a = SealedClass()
+
+class Outer {
+    inner class Inner
+    typealias TestInner = Inner
+}
+typealias Test5 = Outer.Inner
+
+val test5 = Test5()
+val test5a = Outer.<!UNRESOLVED_REFERENCE!>Inner<!>()
+val test5b = Outer.<!UNRESOLVED_REFERENCE!>TestInner<!>()
+val test5c = Outer().<!UNRESOLVED_REFERENCE!>TestInner<!>()
+val test5d = Outer().Inner()
+val test5e = Outer().<!UNRESOLVED_REFERENCE!>Test5<!>()
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorWrongVisibility.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorWrongVisibility.fir.kt
new file mode 100644
index 00000000000..0fdf9492549
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasConstructorWrongVisibility.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+open class MyClass private constructor(val x: Int) {
+
+    protected constructor(x: String) : this(x.length)
+
+    constructor(x: Double) : this(x.toInt())
+}
+
+typealias MyAlias = MyClass
+
+val test1 = <!INAPPLICABLE_CANDIDATE!>MyAlias<!>(1)
+val test1a = <!INAPPLICABLE_CANDIDATE!>MyClass<!>(1)
+
+val test2 = <!INAPPLICABLE_CANDIDATE!>MyAlias<!>("")
+val test2a = <!INAPPLICABLE_CANDIDATE!>MyClass<!>("")
+
+val test3 = MyAlias(1.0)
+val test3a = MyClass(1.0)
+
+class MyDerived : MyClass(1.0) {
+    val test4 = <!INAPPLICABLE_CANDIDATE!>MyAlias<!>(1)
+    val test4a = <!INAPPLICABLE_CANDIDATE!>MyClass<!>(1)
+    val test5 = MyAlias("")
+    val test5a = MyClass("")
+    val test6 = MyAlias(1.0)
+    val test6a = MyClass(1.0)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasExpansionRepeatedAnnotations.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasExpansionRepeatedAnnotations.fir.kt
new file mode 100644
index 00000000000..faeac4d3906
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasExpansionRepeatedAnnotations.fir.kt
@@ -0,0 +1,16 @@
+@Target(AnnotationTarget.TYPE)
+annotation class A
+
+typealias AInt = @A Int
+typealias AI = AInt
+
+typealias Test1 = @A AInt
+typealias Test2 = @A AI
+typealias Test3 = List<@A AInt>
+typealias Test4 = List<@A AI>
+
+val testProperty1: @A AInt = 0
+val testProperty2: @A AI = 0
+
+fun testFunction1(x: @A AInt): @A AInt = x
+fun testFunction2(x: @A AI): @A AI = x
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.fir.kt
new file mode 100644
index 00000000000..34d52277449
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasForProjectionInSuperInterfaces.fir.kt
@@ -0,0 +1,32 @@
+interface Inv<T>
+interface Out<out T>
+interface In<in T>
+
+typealias InvStar = Inv<*>
+typealias InvIn = Inv<in Int>
+typealias InvOut = Inv<out Int>
+typealias InvT<T> = Inv<T>
+
+typealias OutStar = Out<*>
+typealias OutOut = Out<out Int>
+typealias OutT<T> = Out<T>
+
+typealias InStar = In<*>
+typealias InIn = In<in Int>
+typealias InT<T> = In<T>
+
+class Test1 : InvStar
+class Test2 : InvIn
+class Test3 : InvOut
+class Test4 : InvT<*>
+class Test5 : InvT<InvT<*>>
+
+class Test6 : OutStar
+class Test7 : OutOut
+class Test8 : OutT<Int>
+class Test9 : OutT<out Int>
+
+class Test10 : InStar
+class Test11 : InIn
+class Test12 : InT<Int>
+class Test13 : InT<in Int>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasInAnonymousObjectType.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasInAnonymousObjectType.fir.kt
new file mode 100644
index 00000000000..7567522a5b3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasInAnonymousObjectType.fir.kt
@@ -0,0 +1,5 @@
+open class Foo<T>
+
+typealias FooStr = Foo<String>
+
+val test = object : FooStr() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasInvisibleObject.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasInvisibleObject.fir.kt
new file mode 100644
index 00000000000..d11df54d662
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasInvisibleObject.fir.kt
@@ -0,0 +1,8 @@
+class C {
+    private companion object
+}
+
+typealias CAlias = C
+
+val test1 = CAlias
+val test1a = C
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasNotNull.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasNotNull.fir.kt
new file mode 100644
index 00000000000..285064d139a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasNotNull.fir.kt
@@ -0,0 +1,6 @@
+typealias Processor = (number: Int) -> Unit
+typealias Handler = (String) -> Processor?
+
+fun x(handler: Handler) {
+    return handler("a")!!(1)
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasObject.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasObject.fir.kt
new file mode 100644
index 00000000000..72e1b26402f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasObject.fir.kt
@@ -0,0 +1,32 @@
+object AnObject {
+    val ok = "OK"
+    fun foo() = "OK"
+}
+
+typealias TestObject = AnObject
+
+val test11: AnObject = TestObject
+val test12: TestObject = TestObject
+val test13: String = TestObject.<!UNRESOLVED_REFERENCE!>ok<!>
+val test14: String = TestObject.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+typealias TestObject2 = TestObject
+
+val test21: AnObject = TestObject2
+val test22: TestObject2 = TestObject2
+val test23: String = TestObject2.<!UNRESOLVED_REFERENCE!>ok<!>
+val test24: String = TestObject2.<!UNRESOLVED_REFERENCE!>foo<!>()
+
+class ClassWithCompanion {
+    companion object {
+        val ok = "OK"
+        fun foo() = "OK"
+    }
+}
+
+typealias TestCWC = ClassWithCompanion
+
+val test35: ClassWithCompanion.Companion = TestCWC
+val test36 = TestCWC
+val test37: String = TestCWC.<!UNRESOLVED_REFERENCE!>ok<!>
+val test38: String = TestCWC.<!UNRESOLVED_REFERENCE!>foo<!>()
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasObjectWithInvoke.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasObjectWithInvoke.fir.kt
new file mode 100644
index 00000000000..958b5f28c16
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasObjectWithInvoke.fir.kt
@@ -0,0 +1,24 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+object ObjectWithInvoke {
+    operator fun invoke() = this
+}
+
+class ClassWithCompanionObjectWithInvoke {
+    companion object {
+        operator fun invoke(x: Any) = x
+    }
+}
+
+typealias WI = ObjectWithInvoke
+
+typealias CWI = ClassWithCompanionObjectWithInvoke
+
+val test1 = <!INAPPLICABLE_CANDIDATE!>WI<!>()
+val test2 = <!INAPPLICABLE_CANDIDATE!>WI<!>(null)
+
+val test3 = CWI()
+val test4 = <!INAPPLICABLE_CANDIDATE!>CWI<!>("")
+val test5 = <!INAPPLICABLE_CANDIDATE!>CWI<!>(null)
+val test5a = <!INAPPLICABLE_CANDIDATE!>ClassWithCompanionObjectWithInvoke<!>(null)
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasShouldExpandToClass.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasShouldExpandToClass.fir.kt
new file mode 100644
index 00000000000..ba72e03fbe7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasShouldExpandToClass.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -TOPLEVEL_TYPEALIASES_ONLY
+
+typealias ToTypeParam1<T> = T
+typealias ToTypeParam2<T> = ToTypeParam1<T>
+typealias ToTypeParam3<T1, T2> = ToTypeParam2<T1>
+typealias ToTypeParam4 = ToTypeParam1<Any>
+
+typealias ToFun1 = () -> Unit
+typealias ToFun2<T> = (T) -> Unit
+
+class Outer {
+    typealias ToTypeParam1<T> = T
+    typealias ToTypeParam2<T> = ToTypeParam1<T>
+    typealias ToTypeParam3<T1, T2> = ToTypeParam2<T1>
+    typealias ToTypeParam4 = ToTypeParam1<Any>
+}
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasesInImportDirectives.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasesInImportDirectives.fir.kt
new file mode 100644
index 00000000000..d2d21ee4dda
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasesInImportDirectives.fir.kt
@@ -0,0 +1,47 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+// FILE: foo.kt
+
+package test
+
+typealias ClassAlias = ClassSample
+typealias ObjectAlias = ObjectSample
+typealias EnumAlias = EnumSample
+
+class ClassSample {
+    class Nested1
+}
+
+object ObjectSample {
+    class Nested2
+}
+
+enum class EnumSample {
+    Entry;
+
+    class Nested3
+}
+
+// FILE: test.kt
+
+import test.ClassAlias
+import test.ClassAlias.Nested1
+
+import test.ClassSample.Nested1.*
+import test.ClassAlias.Nested1.*
+
+import test.ObjectAlias
+import test.ObjectAlias.Nested2
+
+import test.ObjectSample.Nested2.*
+import test.ObjectAlias.Nested2.*
+
+import test.EnumAlias
+import test.EnumAlias.Nested3
+
+import test.EnumSample.Nested3.*
+import test.EnumAlias.Nested3.*
+
+import test.EnumAlias.Entry
+
+fun f() {}
diff --git a/compiler/testData/diagnostics/tests/typealias/typeAliasesInQualifiers.fir.kt b/compiler/testData/diagnostics/tests/typealias/typeAliasesInQualifiers.fir.kt
new file mode 100644
index 00000000000..5132f4a66f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typeAliasesInQualifiers.fir.kt
@@ -0,0 +1,75 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_EXPRESSION
+
+// FILE: foo.kt
+
+package test
+
+typealias ClassAlias = ClassSample
+typealias ObjectAlias = ObjectSample
+typealias EnumAlias = EnumSample
+
+class ClassSample {
+    class Nested {
+        fun func() {}
+    }
+
+    fun func() {}
+}
+
+object ObjectSample {
+    class Nested {
+        fun func() {}
+    }
+
+    fun func() {}
+}
+
+enum class EnumSample {
+    Entry;
+
+    class Nested {
+        fun func() {}
+    }
+
+    fun func() {}
+}
+
+// FILE: test.kt
+
+fun foo(
+    a0: test.ClassSample.Nested,
+    a1: test.ClassAlias.Nested,
+
+    b0: test.ObjectSample.Nested,
+    b1: test.ObjectAlias.Nested,
+
+    c0: test.EnumSample.Nested,
+    c1: test.EnumAlias.Nested
+) {
+    test.ClassSample::Nested
+    test.ClassAlias::Nested
+
+    test.ClassSample::func
+    test.ClassAlias::func
+
+    test.ClassSample.Nested::func
+    test.ClassAlias.<!UNRESOLVED_REFERENCE!>Nested<!>::func
+
+    test.ObjectSample::Nested
+    test.ObjectAlias::Nested
+
+    test.ObjectSample::func
+    test.ObjectAlias::func
+
+    test.ObjectSample.Nested::func
+    test.ObjectAlias.<!UNRESOLVED_REFERENCE!>Nested<!>::func
+
+    test.EnumSample::Nested
+    test.EnumAlias::Nested
+
+    test.EnumSample::func
+    test.EnumAlias::func
+
+    test.EnumSample.Nested::func
+    test.EnumAlias.<!UNRESOLVED_REFERENCE!>Nested<!>::func
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotations.fir.kt b/compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotations.fir.kt
new file mode 100644
index 00000000000..5d30894a70d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotations.fir.kt
@@ -0,0 +1,16 @@
+@Target(AnnotationTarget.TYPE)
+annotation class Ann1
+
+@Target(AnnotationTarget.TYPE)
+annotation class Ann2
+
+typealias Alias1 = @Ann1 String
+typealias Alias2 = @Ann2 Alias1
+fun test1(a: Alias2) = a
+
+// NB @ExtensionFunctionType on non-functional type is not an error
+typealias Alias3 = @ExtensionFunctionType Alias1
+fun test2(a: Alias3) = a
+
+typealias LA1 = List<@Ann2 Alias1>
+fun test3(la1: LA1) = la1
diff --git a/compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotationsInArguments.fir.kt b/compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotationsInArguments.fir.kt
new file mode 100644
index 00000000000..1f635bb621a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typealiasRhsAnnotationsInArguments.fir.kt
@@ -0,0 +1,11 @@
+@Target(AnnotationTarget.TYPE)
+annotation class Ann1
+
+@Target(AnnotationTarget.TYPE)
+annotation class Ann2
+
+class C<T>
+
+typealias CA<T> = C<@Ann1 T>
+
+fun test(x: CA<@Ann2 Int>) = x
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/typealiasRhsRepeatedAnnotationInArguments.fir.kt b/compiler/testData/diagnostics/tests/typealias/typealiasRhsRepeatedAnnotationInArguments.fir.kt
new file mode 100644
index 00000000000..5936c10fb09
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typealiasRhsRepeatedAnnotationInArguments.fir.kt
@@ -0,0 +1,6 @@
+@Target(AnnotationTarget.TYPE)
+annotation class A
+
+typealias Gen<T> = List<@A T>
+
+typealias Test1 = Gen<@A Int>
diff --git a/compiler/testData/diagnostics/tests/typealias/typealiasRhsRepeatedAnnotations.fir.kt b/compiler/testData/diagnostics/tests/typealias/typealiasRhsRepeatedAnnotations.fir.kt
new file mode 100644
index 00000000000..0d7b4dc99b5
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/typealiasRhsRepeatedAnnotations.fir.kt
@@ -0,0 +1,4 @@
+@Target(AnnotationTarget.TYPE)
+annotation class A
+
+typealias Test1 = @A @A Int
diff --git a/compiler/testData/diagnostics/tests/typealias/unsupportedTypeAlias.fir.kt b/compiler/testData/diagnostics/tests/typealias/unsupportedTypeAlias.fir.kt
new file mode 100644
index 00000000000..c5f2135351d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/unsupportedTypeAlias.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: -TypeAliases
+
+class C
+
+typealias S = String
+typealias L<T> = List<T>
+typealias CA = C
+typealias Unused = Any
+
+val test1: S = ""
+
+fun test2(x: L<S>) = x
+
+class Test3 : CA()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/typealias/unusedTypeAliasParameter.fir.kt b/compiler/testData/diagnostics/tests/typealias/unusedTypeAliasParameter.fir.kt
new file mode 100644
index 00000000000..ae5caa6933a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/unusedTypeAliasParameter.fir.kt
@@ -0,0 +1,2 @@
+typealias Test<T, X> = List<T>
+typealias Test2<T, X> = Test<T, X>
diff --git a/compiler/testData/diagnostics/tests/typealias/wrongNumberOfArgumentsInTypeAliasConstructor.fir.kt b/compiler/testData/diagnostics/tests/typealias/wrongNumberOfArgumentsInTypeAliasConstructor.fir.kt
new file mode 100644
index 00000000000..4a15293d85c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/typealias/wrongNumberOfArgumentsInTypeAliasConstructor.fir.kt
@@ -0,0 +1,42 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+class Pair<T1, T2>(val x1: T1, val x2: T2)
+
+typealias P<T1, T2> = Pair<T1, T2>
+
+typealias P2<T> = Pair<T, T>
+
+typealias PR<T1, T2> = Pair<T2, T1>
+
+val test0 = P(1, 2)
+val test1 = P<Int>(1, 2)
+val test2 = P<Int, Int>(1, 2)
+val test3 = P<Int, Int, Int>(1, 2)
+
+val test0p2 = P2(1, 1)
+val test0p2a = P2(1, "")
+val test1p2 = P2<Int>(1, 1)
+val test2p2 = P2<Int, Int>(1, 1)
+val test3p2 = P2<Int, Int, Int>(1, 1)
+
+val test0pr = PR(1, "")
+val test1pr = <!INAPPLICABLE_CANDIDATE!>PR<!><Int>(1, "")
+val test2pr = <!INAPPLICABLE_CANDIDATE!>PR<!><Int, String>(1, "")
+val test2pra = PR<String, Int>(1, "")
+val test3pr = <!INAPPLICABLE_CANDIDATE!>P2<!><String, Int, Int>(1, "")
+
+class Num<T : Number>(val x: T)
+typealias N<T> = Num<T>
+
+val testN0 = N("")
+val testN1 = N<Int>(1)
+val testN1a = N<String>("")
+val testN2 = N<Int, Int>(1)
+
+class MyPair<T1 : CharSequence, T2 : Number>(val string: T1, val number: T2)
+typealias MP<T1> = MyPair<String, T1>
+
+val testMP0 = MP<Int>("", 1)
+val testMP1 = <!INAPPLICABLE_CANDIDATE!>MP<!>(1, "")
+val testMP2 = MP<String>("", "")
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/underscoresInNumericLiterals/illegalUnderscores.fir.kt b/compiler/testData/diagnostics/tests/underscoresInNumericLiterals/illegalUnderscores.fir.kt
new file mode 100644
index 00000000000..1833301d78a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/underscoresInNumericLiterals/illegalUnderscores.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+fun foo() {
+    1_
+    0x_f
+    0X_f
+    0b_1
+    0B_1
+    1.0_
+    1_.1
+    1.0_e1
+    1.0E_1
+    0Xe_
+    1.1_e-1_23
+    1.0e+_0
+    1.0e-_0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/underscoresInNumericLiterals/noUnderscores.fir.kt b/compiler/testData/diagnostics/tests/underscoresInNumericLiterals/noUnderscores.fir.kt
new file mode 100644
index 00000000000..2de40181060
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/underscoresInNumericLiterals/noUnderscores.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: -UnderscoresInNumericLiterals
+// !DIAGNOSTICS: -UNUSED_EXPRESSION
+
+fun foo() {
+    100_1
+    3_.1
+    2___4
+    123_
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/unit/nullableUnit.fir.kt b/compiler/testData/diagnostics/tests/unit/nullableUnit.fir.kt
new file mode 100644
index 00000000000..42d2f77036a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/unit/nullableUnit.fir.kt
@@ -0,0 +1,5 @@
+fun foo() {}
+
+val x: Unit? = when ("A") {
+    "B" -> foo()
+}
diff --git a/compiler/testData/diagnostics/tests/unproperDefaultInitializationInTailrec.fir.kt b/compiler/testData/diagnostics/tests/unproperDefaultInitializationInTailrec.fir.kt
new file mode 100644
index 00000000000..19d2b6eeffa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/unproperDefaultInitializationInTailrec.fir.kt
@@ -0,0 +1,39 @@
+//!LANGUAGE: -ProperComputationOrderOfTailrecDefaultParameters
+
+import kotlin.reflect.KClass
+
+fun withEffects(): String = "OK"
+
+const val Z = "123"
+
+enum class EnumA {
+    A
+}
+
+tailrec fun foo(i: Int = 1, c: Char = '2', s: String = "1234", b: Boolean = true, d: Double = 1.0,  l: Long =  1L,  y: String = withEffects()) {
+    foo(i, c, s, b, d, l, y)
+}
+
+tailrec fun foo2(x: Int = 1, y: String = withEffects(), z: String = Z) {
+    foo2(x, y, z)
+}
+
+tailrec fun foo3(y: String = withEffects()) {
+    foo3(y)
+}
+
+tailrec fun foo4(x: String = withEffects(), y: String = withEffects()) {
+    foo4(x, y)
+}
+
+tailrec fun foo5(x: String = withEffects(), y: String = withEffects(), z: String = withEffects()) {
+    foo5(x, y, z)
+}
+
+tailrec fun foo6(x: String = withEffects(), y: EnumA = EnumA.A) {
+    foo6(x, y)
+}
+
+tailrec fun foo7(x: String = withEffects(), y: KClass<out EnumA> = EnumA.A::class) {
+    foo7(x, y)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/AmbiguousVararg.fir.kt b/compiler/testData/diagnostics/tests/varargs/AmbiguousVararg.fir.kt
new file mode 100644
index 00000000000..9bd9ae98207
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/AmbiguousVararg.fir.kt
@@ -0,0 +1,6 @@
+fun foo(vararg t : String) = ""
+fun foo(vararg t : Int) = ""
+
+fun test() {
+    foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/MoreSpecificVarargsOfEqualLength.fir.kt b/compiler/testData/diagnostics/tests/varargs/MoreSpecificVarargsOfEqualLength.fir.kt
new file mode 100644
index 00000000000..d820de2c83f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/MoreSpecificVarargsOfEqualLength.fir.kt
@@ -0,0 +1,9 @@
+fun main(d : D) {
+    d.from("")
+    d.from(1)
+}
+
+class D {
+    fun from(vararg a : Any){}
+    fun from(vararg a : String){}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/MostSepcificVarargsWithJava.fir.kt b/compiler/testData/diagnostics/tests/varargs/MostSepcificVarargsWithJava.fir.kt
new file mode 100644
index 00000000000..dfb55e3a99f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/MostSepcificVarargsWithJava.fir.kt
@@ -0,0 +1,19 @@
+// FILE: kotlin.kt
+fun main(j : C, s : Array<String?>) {
+    j.from()
+    j.from("")
+    j.from("", "")
+    j.<!AMBIGUITY!>from<!>("", "", "")
+
+    j.<!AMBIGUITY!>from<!>("", *s) // This should not be an ambiguity, see KT-1842
+    j.from(*s)
+}
+
+// FILE: C.java
+public class C {
+    void from() {}
+    void from(String s) {}
+    void from(String s, String s1) {}
+    void from(String... s) {}
+    void from(String s1, String... s) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/NilaryVsVararg.fir.kt b/compiler/testData/diagnostics/tests/varargs/NilaryVsVararg.fir.kt
new file mode 100644
index 00000000000..15e7efdc923
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/NilaryVsVararg.fir.kt
@@ -0,0 +1,10 @@
+fun foo0() : String = "noarg"
+
+fun foo0(vararg t : Int) : String = "vararg"
+
+fun test0() {
+    foo0()
+    foo0(1)
+    val a = IntArray(0)
+    foo0(*a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/NullableTypeForVarargArgument.fir.kt b/compiler/testData/diagnostics/tests/varargs/NullableTypeForVarargArgument.fir.kt
new file mode 100644
index 00000000000..458239df8a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/NullableTypeForVarargArgument.fir.kt
@@ -0,0 +1,66 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS:-UNUSED_PARAMETER
+
+// KT-9883 prohibit using spread operator for nullable value
+
+// FILE: A.java
+
+public class A {
+    public void foo(int x, String ... args) {}
+    public static String[] ar;
+}
+
+// FILE: J.java
+
+public class J {
+    public interface Invoke {
+        void invoke(String ...args);
+    }
+
+    public static Invoke staticFun;
+}
+
+// FILE: 1.kt
+val args: Array<String>? = null
+
+fun bar(x: Int, vararg s: String) {}
+
+fun baz(s: String) {}
+
+fun getArr(): Array<String>? = null
+
+fun f() {
+    A().foo(1, *args)
+    bar(2, *args)
+    <!INAPPLICABLE_CANDIDATE!>baz<!>(*args)
+}
+
+fun g(args: Array<String>?) {
+
+    if (args != null) {
+        A().foo(1, *args)
+    }
+    A().foo(1, *A.ar)
+}
+
+class B {
+    var args: Array<String>? = null
+}
+
+fun h(b: B) {
+    if (b.args != null) {
+        A().foo(1, *b.args)
+    }
+}
+
+fun k() {
+    A().foo(1, *getArr())
+    bar(2, *getArr())
+    <!INAPPLICABLE_CANDIDATE!>baz<!>(*getArr())
+}
+
+fun invokeTest(goodArgs: Array<String>) {
+    J.staticFun(*goodArgs)
+    J.staticFun(*args)
+    J.staticFun(*args ?: null)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/UnaryVsVararg.fir.kt b/compiler/testData/diagnostics/tests/varargs/UnaryVsVararg.fir.kt
new file mode 100644
index 00000000000..015513edea1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/UnaryVsVararg.fir.kt
@@ -0,0 +1,9 @@
+fun foo1(a : Int) : String = "noarg"
+
+fun foo1(a : Int, vararg t : Int) : String = "vararg"
+
+fun test1() {
+    foo1(1)
+    val a = IntArray(0)
+    foo1(1, *a)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/assignNonConstSingleArrayElementAsVarargInAnnotation.fir.kt b/compiler/testData/diagnostics/tests/varargs/assignNonConstSingleArrayElementAsVarargInAnnotation.fir.kt
new file mode 100644
index 00000000000..fe68f83f245
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/assignNonConstSingleArrayElementAsVarargInAnnotation.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: -ProhibitNonConstValuesAsVarargsInAnnotations, -ProhibitAssigningSingleElementsToVarargsInNamedForm
+
+val nonConstArray = longArrayOf(0)
+fun nonConstFun(): LongArray = TODO()
+
+fun nonConstLong(): Long = TODO()
+
+annotation class Anno(vararg val value: Long)
+
+@Anno(value = nonConstArray)
+fun foo1() {}
+
+@Anno(value = nonConstFun())
+fun foo2() {}
+
+@Anno(value = longArrayOf(nonConstLong()))
+fun foo3() {}
+
+@Anno(value = [nonConstLong()])
+fun foo4() {}
+
+@Anno(value = *nonConstArray)
+fun bar1() {}
+
+@Anno(*nonConstArray)
+fun bar2() {}
diff --git a/compiler/testData/diagnostics/tests/varargs/assignNonConstSingleArrayElementAsVarargInAnnotationError.fir.kt b/compiler/testData/diagnostics/tests/varargs/assignNonConstSingleArrayElementAsVarargInAnnotationError.fir.kt
new file mode 100644
index 00000000000..0fde992f5d8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/assignNonConstSingleArrayElementAsVarargInAnnotationError.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: +ProhibitNonConstValuesAsVarargsInAnnotations, +ProhibitAssigningSingleElementsToVarargsInNamedForm
+
+val nonConstArray = longArrayOf(0)
+fun nonConstFun(): LongArray = TODO()
+
+fun nonConstLong(): Long = TODO()
+
+annotation class Anno(vararg val value: Long)
+
+@Anno(value = nonConstArray)
+fun foo1() {}
+
+@Anno(value = nonConstFun())
+fun foo2() {}
+
+@Anno(value = longArrayOf(nonConstLong()))
+fun foo3() {}
+
+@Anno(value = [nonConstLong()])
+fun foo4() {}
+
+@Anno(value = *nonConstArray)
+fun bar1() {}
+
+@Anno(*nonConstArray)
+fun bar2() {}
diff --git a/compiler/testData/diagnostics/tests/varargs/assigningArraysToVarargsInAnnotations.fir.kt b/compiler/testData/diagnostics/tests/varargs/assigningArraysToVarargsInAnnotations.fir.kt
new file mode 100644
index 00000000000..115ec1bc83e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/assigningArraysToVarargsInAnnotations.fir.kt
@@ -0,0 +1,46 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ArrayLiteralsInAnnotations, +AssigningArraysToVarargsInNamedFormInAnnotations
+
+// FILE: JavaAnn.java
+
+@interface JavaAnn {
+    String[] value() default {};
+    String[] path() default {};
+}
+
+// FILE: test.kt
+
+annotation class Ann(vararg val s: String)
+
+@Ann(s = arrayOf())
+fun test1() {}
+
+@Ann(s = intArrayOf())
+fun test2() {}
+
+@Ann(s = arrayOf(1))
+fun test3() {}
+
+@Ann("value1", "value2")
+fun test4() {}
+
+@Ann(s = ["value"])
+fun test5() {}
+
+@JavaAnn(value = arrayOf("value"))
+fun jTest1() {}
+
+@JavaAnn(value = ["value"])
+fun jTest2() {}
+
+@JavaAnn(value = ["value"], path = ["path"])
+fun jTest3() {}
+
+
+annotation class IntAnn(vararg val i: Int)
+
+@IntAnn(i = [1, 2])
+fun foo1() {}
+
+@IntAnn(i = intArrayOf(0))
+fun foo2() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormAnnDeprecation_after.fir.kt b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormAnnDeprecation_after.fir.kt
new file mode 100644
index 00000000000..80eef870bb9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormAnnDeprecation_after.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +ArrayLiteralsInAnnotations, +AssigningArraysToVarargsInNamedFormInAnnotations, +ProhibitAssigningSingleElementsToVarargsInNamedForm
+
+// FILE: JavaAnn.java
+
+@interface JavaAnn {
+    String[] value() default {};
+    String[] path() default {};
+}
+
+// FILE: test.kt
+
+annotation class Ann(vararg val s: String)
+
+@Ann(s = "value")
+fun test1() {}
+
+@Ann(s = *arrayOf("value"))
+fun test2() {}
+
+@Ann(s = *["value"])
+fun test3() {}
+
+@JavaAnn(value = "value")
+fun test4() {}
+
+@JavaAnn("value", path = arrayOf("path"))
+fun test5() {}
+
+@JavaAnn("value", path = ["path"])
+fun test6() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormAnnDeprecation_before.fir.kt b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormAnnDeprecation_before.fir.kt
new file mode 100644
index 00000000000..b08c422c1cb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormAnnDeprecation_before.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +ArrayLiteralsInAnnotations, +AssigningArraysToVarargsInNamedFormInAnnotations, -ProhibitAssigningSingleElementsToVarargsInNamedForm
+
+// FILE: JavaAnn.java
+
+@interface JavaAnn {
+    String[] value() default {};
+    String[] path() default {};
+}
+
+// FILE: test.kt
+
+annotation class Ann(vararg val s: String)
+
+@Ann(s = "value")
+fun test1() {}
+
+@Ann(s = *arrayOf("value"))
+fun test2() {}
+
+@Ann(s = *["value"])
+fun test3() {}
+
+@JavaAnn(value = "value")
+fun test4() {}
+
+@JavaAnn("value", path = arrayOf("path"))
+fun test5() {}
+
+@JavaAnn("value", path = ["path"])
+fun test6() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormFunDeprecation_after.fir.kt b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormFunDeprecation_after.fir.kt
new file mode 100644
index 00000000000..d81b18def58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormFunDeprecation_after.fir.kt
@@ -0,0 +1,60 @@
+// !LANGUAGE: +AssigningArraysToVarargsInNamedFormInAnnotations, +ProhibitAssigningSingleElementsToVarargsInNamedForm
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+fun foo(vararg s: Int) {}
+
+open class Cls(vararg p: Long)
+
+fun test(i: IntArray) {
+    foo(s = 1)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(s = i)
+    foo(s = *i)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(s = intArrayOf(1))
+    foo(s = *intArrayOf(1))
+    foo(1)
+
+    Cls(p = 1)
+
+    class Sub : Cls(p = 1)
+
+    val c = object : Cls(p = 1) {}
+
+    foo(s = *intArrayOf(elements = 1))
+}
+
+
+fun anyFoo(vararg a: Any) {}
+
+fun testAny() {
+    anyFoo(a = "")
+    anyFoo(a = arrayOf(""))
+    anyFoo(a = *arrayOf(""))
+}
+
+fun <T> genFoo(vararg t: T) {}
+
+fun testGen() {
+    genFoo<Int>(t = 1)
+    genFoo<Int?>(t = null)
+    genFoo<Array<Int>>(t = arrayOf())
+    genFoo<Array<Int>>(t = *arrayOf(arrayOf()))
+
+    genFoo(t = "")
+    genFoo(t = arrayOf(""))
+    genFoo(t = *arrayOf(""))
+}
+
+fun manyFoo(vararg v: Int) {}
+fun manyFoo(vararg s: String) {}
+
+fun testMany(a: Any) {
+    manyFoo(v = 1)
+    manyFoo(s = "")
+
+    <!INAPPLICABLE_CANDIDATE!>manyFoo<!>(a)
+    <!INAPPLICABLE_CANDIDATE!>manyFoo<!>(v = a)
+    <!INAPPLICABLE_CANDIDATE!>manyFoo<!>(s = a)
+    manyFoo(v = a as Int)
+    manyFoo(s = a as String)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormFunDeprecation_before.fir.kt b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormFunDeprecation_before.fir.kt
new file mode 100644
index 00000000000..0ece7246cc7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/assigningSingleElementsInNamedFormFunDeprecation_before.fir.kt
@@ -0,0 +1,60 @@
+// !LANGUAGE: +AssigningArraysToVarargsInNamedFormInAnnotations, -ProhibitAssigningSingleElementsToVarargsInNamedForm
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+fun foo(vararg s: Int) {}
+
+open class Cls(vararg p: Long)
+
+fun test(i: IntArray) {
+    foo(s = 1)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(s = i)
+    foo(s = *i)
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(s = intArrayOf(1))
+    foo(s = *intArrayOf(1))
+    foo(1)
+
+    Cls(p = 1)
+
+    class Sub : Cls(p = 1)
+
+    val c = object : Cls(p = 1) {}
+
+    foo(s = *intArrayOf(elements = 1))
+}
+
+
+fun anyFoo(vararg a: Any) {}
+
+fun testAny() {
+    anyFoo(a = "")
+    anyFoo(a = arrayOf(""))
+    anyFoo(a = *arrayOf(""))
+}
+
+fun <T> genFoo(vararg t: T) {}
+
+fun testGen() {
+    genFoo<Int>(t = 1)
+    genFoo<Int?>(t = null)
+    genFoo<Array<Int>>(t = arrayOf())
+    genFoo<Array<Int>>(t = *arrayOf(arrayOf()))
+
+    genFoo(t = "")
+    genFoo(t = arrayOf(""))
+    genFoo(t = *arrayOf(""))
+}
+
+fun manyFoo(vararg v: Int) {}
+fun manyFoo(vararg s: String) {}
+
+fun testMany(a: Any) {
+    manyFoo(v = 1)
+    manyFoo(s = "")
+
+    <!INAPPLICABLE_CANDIDATE!>manyFoo<!>(a)
+    <!INAPPLICABLE_CANDIDATE!>manyFoo<!>(v = a)
+    <!INAPPLICABLE_CANDIDATE!>manyFoo<!>(s = a)
+    manyFoo(v = a as Int)
+    manyFoo(s = a as String)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/kt1781.fir.kt b/compiler/testData/diagnostics/tests/varargs/kt1781.fir.kt
new file mode 100644
index 00000000000..f34215e5342
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/kt1781.fir.kt
@@ -0,0 +1,13 @@
+// FILE: kotlin.kt
+fun foo() {
+  JavaClass()
+  JavaClass("")
+}
+
+// FILE: JavaClass.java
+
+public class JavaClass {
+    public JavaClass() {  }
+
+    public JavaClass(String... ss) {  }
+}
diff --git a/compiler/testData/diagnostics/tests/varargs/kt1835.fir.kt b/compiler/testData/diagnostics/tests/varargs/kt1835.fir.kt
new file mode 100644
index 00000000000..f55f90935aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/kt1835.fir.kt
@@ -0,0 +1,12 @@
+// FILE: JavaClass.java
+public class JavaClass {
+    void from(String s) {}
+    void from(String... s) {}
+}
+
+// FILE: kotlin.kt
+fun main() {
+    JavaClass().from()
+    JavaClass().from("")
+    JavaClass().from("", "")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/kt1838-param.fir.kt b/compiler/testData/diagnostics/tests/varargs/kt1838-param.fir.kt
new file mode 100644
index 00000000000..a6ab5e1ea02
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/kt1838-param.fir.kt
@@ -0,0 +1,5 @@
+class A(vararg t : Int) {
+    init {
+        val t1 : IntArray = t
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/varargs/kt1838-val.fir.kt b/compiler/testData/diagnostics/tests/varargs/kt1838-val.fir.kt
new file mode 100644
index 00000000000..c63bf7396d3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/kt1838-val.fir.kt
@@ -0,0 +1,5 @@
+class A(vararg val t : Int) {
+    init {
+        val t1 : IntArray = t
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/varargs/kt2163.fir.kt b/compiler/testData/diagnostics/tests/varargs/kt2163.fir.kt
new file mode 100644
index 00000000000..79ea4dc8fb7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/kt2163.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun printAll(vararg a : Any) {}
+
+fun main(args: Array<String>) {
+    <!INAPPLICABLE_CANDIDATE!>printAll<!>(*args) // Shouldn't be an error
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/kt422.fir.kt b/compiler/testData/diagnostics/tests/varargs/kt422.fir.kt
new file mode 100644
index 00000000000..fa5791cae47
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/kt422.fir.kt
@@ -0,0 +1,17 @@
+// KT-422 Tune literal typing rules so that varargs overloaded by primitive types work
+
+fun <T> foo(vararg t : T) = t
+fun foo(vararg a: Int) = a
+fun foo(vararg a: Long) = a
+
+fun test() {
+    foo(1, 2, 3) // Error, but should be foo of ints
+}
+
+fun <T> array(vararg elements : T) = elements
+fun array(vararg elements : Int) = elements
+
+fun test1() {
+    array("A", "A")
+    array(1, 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/noAssigningArraysToVarargsFeature.fir.kt b/compiler/testData/diagnostics/tests/varargs/noAssigningArraysToVarargsFeature.fir.kt
new file mode 100644
index 00000000000..966f4dde6ec
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/noAssigningArraysToVarargsFeature.fir.kt
@@ -0,0 +1,49 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +ArrayLiteralsInAnnotations, -AssigningArraysToVarargsInNamedFormInAnnotations
+
+// FILE: JavaAnn.java
+
+@interface JavaAnn {
+    String[] value() default {};
+    String[] path() default {};
+}
+
+// FILE: test.kt
+
+annotation class Ann(vararg val s: String)
+
+@Ann(s = arrayOf())
+fun test1() {}
+
+@Ann(s = intArrayOf())
+fun test2() {}
+
+@Ann(s = arrayOf(1))
+fun test3() {}
+
+@Ann(s = ["value"])
+fun test5() {}
+
+@JavaAnn(value = arrayOf("value"))
+fun jTest1() {}
+
+@JavaAnn(value = ["value"])
+fun jTest2() {}
+
+@JavaAnn(value = ["value"], path = ["path"])
+fun jTest3() {}
+
+annotation class IntAnn(vararg val i: Int)
+
+@IntAnn(i = [1, 2])
+fun foo1() {}
+
+@IntAnn(i = intArrayOf(0))
+fun foo2() {}
+
+fun foo(vararg i: Int) {}
+
+@Ann(s = "value")
+fun dep1() {
+    foo(i = 1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/prohibitAssigningSingleElementsInNamedForm.fir.kt b/compiler/testData/diagnostics/tests/varargs/prohibitAssigningSingleElementsInNamedForm.fir.kt
new file mode 100644
index 00000000000..d186912901c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/prohibitAssigningSingleElementsInNamedForm.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +ProhibitAssigningSingleElementsToVarargsInNamedForm
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+annotation class Anno1(vararg val s: String)
+annotation class Anno2(vararg val i: Int)
+
+@Anno1(s = "foo")
+@Anno2(i = *intArrayOf(1))
+fun f1() {}
+
+@Anno1(s = ["foo"])
+@Anno2(i = intArrayOf(1))
+fun f2() {}
+
+fun foo(vararg ints: Int) {}
+
+fun test() {
+    foo(ints = 1)
+    foo(ints = *intArrayOf(1))
+}
diff --git a/compiler/testData/diagnostics/tests/varargs/varargInSetter.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargInSetter.fir.kt
new file mode 100644
index 00000000000..2a9b2059798
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargInSetter.fir.kt
@@ -0,0 +1,6 @@
+class My {
+    var x: String = ""
+        set(vararg value) {
+            x = value
+        }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/varargIterator.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargIterator.fir.kt
new file mode 100644
index 00000000000..b1f1dbcc919
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargIterator.fir.kt
@@ -0,0 +1,5 @@
+package test
+
+class CompositeIterator<T>(vararg iterators: java.util.Iterator<T>){
+    val iteratorsIter = iterators.iterator()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/varargOfNothing.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargOfNothing.fir.kt
new file mode 100644
index 00000000000..36da02c3fb3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargOfNothing.fir.kt
@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun testVarargOfNothing(vararg v: Nothing) {}
+
+fun testVarargOfNNothing(vararg v: Nothing?) {}
+
+fun <T : Nothing?> testVarargOfT(vararg v: T) {}
+
+fun outer() {
+    fun testVarargOfNothing(vararg v: Nothing) {}
+
+    fun testVarargOfNNothing(vararg v: Nothing?) {}
+
+    fun <T : Nothing?> testVarargOfT(vararg v: T) {}
+}
diff --git a/compiler/testData/diagnostics/tests/varargs/varargViewedAsArray.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargViewedAsArray.fir.kt
new file mode 100644
index 00000000000..56f505de853
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargViewedAsArray.fir.kt
@@ -0,0 +1,29 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun stringVararg(vararg args: String) {}
+fun intVararg(vararg args: Int) {}
+fun numberVararg(vararg args: Number) {}
+
+fun useStrings(fn: (String, String, String) -> Unit) = fn("foo", "bar", "boo")
+fun useStringArray(fn: (Array<String>) -> Unit) = fn(arrayOf("foo", "bar", "boo"))
+
+fun useIntArray(fn: (Array<Int>) -> Unit) = fn(arrayOf(1, 2, 3))
+fun usePrimitiveIntArray(fn: (IntArray) -> Unit) = fn(intArrayOf(4, 5, 6))
+
+fun useMixedStringArgs1(fn: (String, Array<String>) -> Unit) = fn("foo", arrayOf("bar", "baz"))
+fun useMixedStringArgs2(fn: (Array<String>, String) -> Unit) = fn(arrayOf("foo", "bar"), "baz")
+fun useMixedStringArgs3(fn: (String, Array<String>, String) -> Unit) = fn("foo", arrayOf("bar", "baz"), "boo")
+fun useTwoStringArrays(fn: (Array<String>, Array<String>) -> Unit) = fn(arrayOf("foo", "bar"), arrayOf("baz", "boo"))
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>useStrings<!>(::stringVararg)
+    useStringArray(::stringVararg)
+    <!INAPPLICABLE_CANDIDATE!>useIntArray<!>(::numberVararg)
+    usePrimitiveIntArray(::intVararg)
+    <!INAPPLICABLE_CANDIDATE!>useIntArray<!>(::intVararg)
+    <!INAPPLICABLE_CANDIDATE!>useMixedStringArgs1<!>(::stringVararg)
+    <!INAPPLICABLE_CANDIDATE!>useMixedStringArgs2<!>(::stringVararg)
+    <!INAPPLICABLE_CANDIDATE!>useMixedStringArgs3<!>(::stringVararg)
+    <!INAPPLICABLE_CANDIDATE!>useTwoStringArrays<!>(::stringVararg)
+}
diff --git a/compiler/testData/diagnostics/tests/varargs/varargsAndFunctionLiterals.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargsAndFunctionLiterals.fir.kt
new file mode 100644
index 00000000000..7771bfe988e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargsAndFunctionLiterals.fir.kt
@@ -0,0 +1,13 @@
+fun f(vararg t : Int, f : ()->Unit) {
+}
+
+fun test() {
+    f {}
+    f() {}
+    f(1) {
+
+    }
+    f(1, 2) {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/varargsAndOut1.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargsAndOut1.fir.kt
new file mode 100644
index 00000000000..04f8ff3f045
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargsAndOut1.fir.kt
@@ -0,0 +1,13 @@
+// !CHECK_TYPE
+
+fun test(vararg a: String) {
+    a checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out String>>() }
+
+    foo(a) checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out String>>() }
+}
+
+fun <T> test1(vararg t: T) {
+    t checkType { <!UNRESOLVED_REFERENCE!>_<!><Array<out T>>() }
+}
+
+fun <T> foo(a: Array<T>): Array<T> = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/varargsAndOut2.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargsAndOut2.fir.kt
new file mode 100644
index 00000000000..ed2a429bbf9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargsAndOut2.fir.kt
@@ -0,0 +1,9 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun bar(vararg a: String) {}
+
+fun test2(a: Array<String>, b: Array<out String>) {
+    bar(*a)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>(*b)
+    <!INAPPLICABLE_CANDIDATE!>bar<!>("", *a, *b, "")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/varargs/varargsAndPair.fir.kt b/compiler/testData/diagnostics/tests/varargs/varargsAndPair.fir.kt
new file mode 100644
index 00000000000..cc2a581ceb8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/varargs/varargsAndPair.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+fun <T: Any> foo(vararg ts: T): T? = null
+
+class Pair<A>(a: A)
+
+fun test() {
+    val v = foo(Pair(1))
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int>(v) // check that it is not error type
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/Class.fir.kt b/compiler/testData/diagnostics/tests/variance/Class.fir.kt
new file mode 100644
index 00000000000..3993b556f6f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/Class.fir.kt
@@ -0,0 +1,23 @@
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+
+interface TypeBounds1<in I, out O, P, X : I>
+interface TypeBounds2<in I, out O, P, X : O>
+interface TypeBounds3<in I, out O, P, X : P>
+interface TypeBounds4<in I, out O, P, X : In<I>>
+interface TypeBounds5<in I, out O, P, X : In<O>>
+
+interface WhereTypeBounds1<in I, out O, P, X> where X : I
+interface WhereTypeBounds2<in I, out O, P, X> where X : O
+interface WhereTypeBounds3<in I, out O, P, X> where X : P
+interface WhereTypeBounds4<in I, out O, P, X> where X : In<I>
+interface WhereTypeBounds5<in I, out O, P, X> where X : In<O>
+
+class SubClass1<in I, out O, P> : Out<I>
+class SubClass2<in I, out O, P> : Out<O>
+class SubClass3<in I, out O, P> : Out<P>
+class SubClass4<in I, out O, P> : In<I>
+class SubClass5<in I, out O, P> : In<O>
+class SubClass6<in I, out O, P> : Inv<O>
+class SubClass7<in I, out O, P> : Inv<I>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/Function.fir.kt b/compiler/testData/diagnostics/tests/variance/Function.fir.kt
new file mode 100644
index 00000000000..f405959daeb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/Function.fir.kt
@@ -0,0 +1,34 @@
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+fun <T> getT(): T = null!!
+
+interface Test<in I, out O, P> {
+    fun parameters1(i: I, o: O, p: P)
+    fun parameters2(i: In<I>)
+    fun parameters3(i: In<O>)
+
+    fun explicitReturnType1() : I
+    fun explicitReturnType2() : O
+    fun explicitReturnType3() : P
+    fun explicitReturnType4() : In<I>
+    fun explicitReturnType5() : In<O>
+
+    fun imlicitReturnType1() = getT<I>()
+    fun imlicitReturnType2() = getT<O>()
+    fun imlicitReturnType3() = getT<P>()
+    fun imlicitReturnType4() = getT<In<I>>()
+    fun imlicitReturnType5() = getT<In<O>>()
+
+    fun I.receiver1()
+    fun O.receiver2()
+    fun P.receiver3()
+    fun In<I>.receiver4()
+    fun In<O>.receiver5()
+
+    fun <X : I> typeParameter1()
+    fun <X : O> typeParameter2()
+    fun <X : P> typeParameter3()
+    fun <X : In<I>> typeParameter4()
+    fun <X : In<O>> typeParameter5()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/FunctionTypes.fir.kt b/compiler/testData/diagnostics/tests/variance/FunctionTypes.fir.kt
new file mode 100644
index 00000000000..edb90a7f81a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/FunctionTypes.fir.kt
@@ -0,0 +1,12 @@
+interface In<in T>
+fun <T> getT(): T = null!!
+
+interface Test<in I, out O, P> {
+    fun ok1(i: (O) -> I) : (I) -> O
+    fun ok2(i: (P) -> P) : (P) -> P
+    fun ok3(i: (In<I>) -> In<O>) = getT<(In<O>) -> In<I>>()
+
+    fun neOk1(i: (I) -> O): (O) -> I
+    fun neOk2(i: (In<O>) -> In<I>)
+    fun neOk3() = getT<(In<I>) -> In<O>>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/InPosition.fir.kt b/compiler/testData/diagnostics/tests/variance/InPosition.fir.kt
new file mode 100644
index 00000000000..f1c532ff27c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/InPosition.fir.kt
@@ -0,0 +1,48 @@
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+interface Pair<out X, out Y>
+
+interface Test<in I, out O, P> {
+    fun ok1(i: I)
+    fun ok2(i: In<O>)
+    fun ok3(i: In<In<I>>)
+    fun ok4(i: Inv<P>)
+    fun ok5(i: P)
+    fun ok6(i: Out<I>)
+    fun ok7(i: Out<Out<I>>)
+    fun ok8(i: Out<In<O>>)
+    fun ok9(i: Out<In<P>>)
+    fun Ok10(i: I)
+    fun Ok11(i: In<O>)
+    fun Ok12(i: In<In<I>>)
+    fun Ok13(i: Out<I>)
+    fun Ok14(i: Pair<In<O>, I>)
+    fun Ok15(i: Inv<out I>)
+
+    fun Ok20(i: Inv<in O>)
+    fun Ok21(i: Inv<in P>)
+    fun Ok22(i: Inv<out I>)
+    fun Ok23(i: Inv<out P>)
+
+    fun neOk1(i: O)
+    fun neOk2(i: In<I>)
+    fun neOk3(i: In<In<O>>)
+    fun neOk4(i: Inv<I>)
+    fun neOk5(i: Inv<O>)
+    fun neOk6(i: In<In<O>>)
+    fun neOk7(i: Pair<In<I>, O>)
+    fun neOk8(i: Inv<out O>)
+    fun neOk9(i: In<out P>)
+    fun neOk10(i: Out<O>)
+
+    fun neOk11(i: Inv<in I>)
+    fun neOk12(i: Inv<out O>)
+
+    fun neOk30(i: Pair<O, >)
+    fun neOk31(i: Pair<O, Inv>)
+    fun neOk32(i: Inv)
+    fun neOk33(i: Inv<<!SYNTAX!><!>>)
+    fun neOk34(i: Inv<C>)
+    fun neOk35(i: Inv<P, P>)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/InvariantPosition.fir.kt b/compiler/testData/diagnostics/tests/variance/InvariantPosition.fir.kt
new file mode 100644
index 00000000000..324b1c9f631
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/InvariantPosition.fir.kt
@@ -0,0 +1,45 @@
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+interface Pair<out X, out Y>
+
+interface Test<in I, out O, P> {
+    var ok1: Inv<P>
+    var ok2: P
+    var ok3: Out<In<P>>
+    var ok4: Pair<In<P>, Out<P>>
+    var ok5: Inv<out P>
+    var ok6: Inv<in P>
+    var ok7: Inv<out P>
+
+    var neOk1: O
+    var neOk2: In<I>
+    var neOk3: In<In<O>>
+    var neOk4: Inv<I>
+    var neOk5: Inv<O>
+    var neOk6: In<In<O>>
+    var neOk7: Pair<In<I>, O>
+    var neOk8: Inv<in O>
+    var neOk9: Inv<in I>
+    var neOk10: In<out I>
+
+    var neOk11: I
+    var neOk12: In<O>
+    var neOk13: In<In<I>>
+    var neOk14: Out<I>
+    var neOk15: Out<Out<I>>
+    var neOk16: Out<In<O>>
+    var neOk17: Pair<In<O>, I>
+
+    var neOk20: Inv<in O>
+    var neOk21: Inv<in I>
+    var neOk22: Inv<out O>
+    var neOk23: Inv<out I>
+
+    var neOk30: Pair<I, >
+    var neOk31: Pair<I, Inv>
+    var neOk32: Inv
+    var neOk33: Inv<<!SYNTAX!><!>>
+    var neOk34: Inv<C>
+    var neOk35: Inv<P, P>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/NullableTypes.fir.kt b/compiler/testData/diagnostics/tests/variance/NullableTypes.fir.kt
new file mode 100644
index 00000000000..66626173ee0
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/NullableTypes.fir.kt
@@ -0,0 +1,16 @@
+interface In<in I>
+interface Out<out O>
+interface Inv<P>
+fun <T> getT(): T = null!!
+
+
+interface Test<in I : Any, out O : Any, P : Any> {
+    fun ok1(i: I?) : O?
+    fun ok2(i: In<O?>?) : Out<O?>?
+    fun ok3(i: Inv<in O?>) = getT<Inv<in I?>>()
+
+    fun neOk1(i: O?) : I?
+    fun neOk(i: Out<O?>?) : In<O?>?
+    fun neOk3(i: Inv<in I?>)
+    fun neOk4() = getT<Inv<in O?>?>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/OutPosition.fir.kt b/compiler/testData/diagnostics/tests/variance/OutPosition.fir.kt
new file mode 100644
index 00000000000..287332912c6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/OutPosition.fir.kt
@@ -0,0 +1,40 @@
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+interface Pair<out X, out Y>
+
+interface Test<in I, out O, P> {
+    fun ok1(): O
+    fun ok2(): In<I>
+    fun ok3(): In<In<O>>
+    fun ok4(): Inv<P>
+    fun ok5(): P
+    fun ok6(): Out<O>
+    fun ok7(): Out<P>
+    fun ok8(): Out<In<P>>
+    fun ok9(): Pair<In<I>, O>
+    
+    fun ok10(): Inv<in I>
+    fun ok11(): Inv<out O>
+    fun ok12(): Inv<in P>
+    fun ok13(): Inv<out P>
+
+    fun neOk1(): I
+    fun neOk2(): In<O>
+    fun neOk3(): In<In<I>>
+    fun neOk4(): Inv<I>
+    fun neOk5(): Inv<O>
+    fun neOk6(): Pair<In<O>, I>
+    fun neOk7(): Inv<in O>
+    fun neOk8(): Out<in I>
+    
+    fun neOk10(): Inv<in O>
+    fun neOk11(): Inv<out I>
+
+    fun neOk30(): Pair<I, >
+    fun neOk31(): Pair<I, Inv>
+    fun neOk32(): Inv
+    fun neOk33(): Inv<<!SYNTAX!><!>>
+    fun neOk34(): Inv<C>
+    fun neOk35(): Inv<P, P>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/PrimaryConstructor.fir.kt b/compiler/testData/diagnostics/tests/variance/PrimaryConstructor.fir.kt
new file mode 100644
index 00000000000..c97cf42397c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/PrimaryConstructor.fir.kt
@@ -0,0 +1,25 @@
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+
+fun <T> getT(): T = null!!
+
+class Test<in I, out O, P>(
+        val type1: I,
+        val type2: O,
+        val type3: P,
+        val type4: In<I>,
+        val type5: In<O>,
+
+        var type6: I,
+        var type7: O,
+        var type8: P,
+        var type9: In<I>,
+        var type0: In<O>,
+
+        type11: I,
+        type12: O,
+        type13: P,
+        type14: In<I>,
+        type15: In<O>
+)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/ValProperty.fir.kt b/compiler/testData/diagnostics/tests/variance/ValProperty.fir.kt
new file mode 100644
index 00000000000..277e2c628ce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/ValProperty.fir.kt
@@ -0,0 +1,50 @@
+import kotlin.reflect.KProperty
+
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+
+class Delegate<T> {
+    operator fun getValue(t: Any, p: KProperty<*>): T = null!!
+    operator fun setValue(t: Any, p: KProperty<*>, value: T) {}
+}
+
+fun <T> getT(): T = null!!
+
+abstract class Test<in I, out O, P> {
+    abstract val type1: I
+    abstract val type2: O
+    abstract val type3: P
+    abstract val type4: In<I>
+    abstract val type5: In<O>
+
+    val implicitType1 = getT<I>()
+    val implicitType2 = getT<O>()
+    val implicitType3 = getT<P>()
+    val implicitType4 = getT<In<I>>()
+    val implicitType5 = getT<In<O>>()
+
+    val delegateType1 by Delegate<I>()
+    val delegateType2 by Delegate<O>()
+    val delegateType3 by Delegate<P>()
+    val delegateType4 by Delegate<In<I>>()
+    val delegateType5 by Delegate<In<O>>()
+
+    abstract val I.receiver1: Int
+    abstract val O.receiver2: Int
+    abstract val P.receiver3: Int
+    abstract val In<I>.receiver4: Int
+    abstract val In<O>.receiver5: Int
+
+    val <X : I> X.typeParameter1: Int get() = 0
+    val <X : O> X.typeParameter2: Int get() = 0
+    val <X : P> X.typeParameter3: Int get() = 0
+    val <X : In<I>> X.typeParameter4: Int get() = 0
+    val <X : In<O>> X.typeParameter5: Int get() = 0
+
+    val <X> X.typeParameter6: Int where X : I get() = 0
+    val <X> X.typeParameter7: Int where X : O get() = 0
+    val <X> X.typeParameter8: Int where X : P get() = 0
+    val <X> X.typeParameter9: Int where X : In<I> get() = 0
+    val <X> X.typeParameter0: Int where X : In<O> get() = 0
+}
diff --git a/compiler/testData/diagnostics/tests/variance/VarProperty.fir.kt b/compiler/testData/diagnostics/tests/variance/VarProperty.fir.kt
new file mode 100644
index 00000000000..a8cb2614b8b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/VarProperty.fir.kt
@@ -0,0 +1,50 @@
+import kotlin.reflect.KProperty
+
+interface In<in T>
+interface Out<out T>
+interface Inv<T>
+
+class Delegate<T> {
+    operator fun getValue(t: Any, p: KProperty<*>): T = null!!
+    operator fun setValue(t: Any, p: KProperty<*>, varue: T) {}
+}
+
+fun <T> getT(): T = null!!
+
+abstract class Test<in I, out O, P> {
+    abstract var type1: I
+    abstract var type2: O
+    abstract var type3: P
+    abstract var type4: In<I>
+    abstract var type5: In<O>
+
+    var implicitType1 = getT<I>()
+    var implicitType2 = getT<O>()
+    var implicitType3 = getT<P>()
+    var implicitType4 = getT<In<I>>()
+    var implicitType5 = getT<In<O>>()
+
+    var delegateType1 by Delegate<I>()
+    var delegateType2 by Delegate<O>()
+    var delegateType3 by Delegate<P>()
+    var delegateType4 by Delegate<In<I>>()
+    var delegateType5 by Delegate<In<O>>()
+
+    abstract var I.receiver1: Int
+    abstract var O.receiver2: Int
+    abstract var P.receiver3: Int
+    abstract var In<I>.receiver4: Int
+    abstract var In<O>.receiver5: Int
+
+    var <X : I> X.typeParameter1: Int get() = 0; set(i) {}
+    var <X : O> X.typeParameter2: Int get() = 0; set(i) {}
+    var <X : P> X.typeParameter3: Int get() = 0; set(i) {}
+    var <X : In<I>> X.typeParameter4: Int get() = 0; set(i) {}
+    var <X : In<O>> X.typeParameter5: Int get() = 0; set(i) {}
+
+    var <X> X.typeParameter6: Int where X : I get() = 0; set(i) {}
+    var <X> X.typeParameter7: Int where X : O get() = 0; set(i) {}
+    var <X> X.typeParameter8: Int where X : P get() = 0; set(i) {}
+    var <X> X.typeParameter9: Int where X : In<I> get() = 0; set(i) {}
+    var <X> X.typeParameter0: Int where X : In<O> get() = 0; set(i) {}
+}
diff --git a/compiler/testData/diagnostics/tests/variance/Visibility.fir.kt b/compiler/testData/diagnostics/tests/variance/Visibility.fir.kt
new file mode 100644
index 00000000000..9cdd40a0c09
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/Visibility.fir.kt
@@ -0,0 +1,20 @@
+interface Test<in I, out O> {
+    val internal_val: I
+    public val public_val: I
+    protected val protected_val: I
+    private val private_val: I
+
+    var interlan_private_set: O
+        private set
+    public var public_private_set: O
+        private set
+    protected var protected_private_set: O
+        private set
+    private var private_private_set: O
+        private set
+
+    fun internal_fun(i: O) : I
+    public fun public_fun(i: O) : I
+    protected fun protected_fun(i: O) : I
+    private fun private_fun(i: O) : I
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/variance/ea1337846.fir.kt b/compiler/testData/diagnostics/tests/variance/ea1337846.fir.kt
new file mode 100644
index 00000000000..bfac78ff16e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/ea1337846.fir.kt
@@ -0,0 +1,21 @@
+// https://ea.jetbrains.com/browser/ea_reports/1337846
+
+//interface ComputablePoint<NumberType : Number>
+//
+//interface ComputableSegment<NumberType: Number, PointType>
+//
+//interface ComputableLineSegment<NumberType: Number, PointType> : ComputableSegment<NumberType, PointType>
+
+//interface Path<NumberType, PointType, SegmentType>
+
+typealias EachSegmentComparator<SegmentType> = (currentSegment: SegmentType, otherSegment: SegmentType, relationship: Int) -> Boolean
+
+interface ComputablePath<NumberType, PointType, out SegmentType>
+    : Path<NumberType, PointType, SegmentType>
+where
+    NumberType: Number,
+    PointType: ComputablePoint<NumberType>,
+    SegmentType: ComputableLineSegment<NumberType, PointType>
+{
+    fun anyTwoSegments(comparator: EachSegmentComparator<ComputableSegment<NumberType, PointType>>): Boolean
+}
diff --git a/compiler/testData/diagnostics/tests/variance/privateToThis/Abstract.fir.kt b/compiler/testData/diagnostics/tests/variance/privateToThis/Abstract.fir.kt
new file mode 100644
index 00000000000..d46d0e62dc8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/privateToThis/Abstract.fir.kt
@@ -0,0 +1,7 @@
+internal abstract class Test</*0*/ in I> {
+    private/*private to this*/ final fun foo(): I {
+        throw Exception()
+    }
+
+    private/*private to this*/ final val i: I get() = foo()
+}
diff --git a/compiler/testData/diagnostics/tests/variance/privateToThis/FunctionCall.fir.kt b/compiler/testData/diagnostics/tests/variance/privateToThis/FunctionCall.fir.kt
new file mode 100644
index 00000000000..66745afaede
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/privateToThis/FunctionCall.fir.kt
@@ -0,0 +1,37 @@
+fun <T> getT(): T = null!!
+
+class Test<in I> {
+    private fun foo() : I = getT()
+
+    fun apply(i: I) {}
+
+    init {
+        foo()
+        this.foo()
+    }
+
+    fun test() {
+        apply(foo())
+        apply(this.foo())
+        with(Test<I>()) {
+            apply(foo()) // resolved to this@Test.foo
+            apply(this.foo())
+            apply(this@with.foo())
+            apply(this@Test.foo())
+        }
+    }
+
+    fun <I> test(t: Test<I>) {
+        t.apply(t.foo())
+    }
+
+    companion object {
+        fun <I> test(t: Test<I>) {
+            t.apply(t.foo())
+        }
+    }
+}
+
+fun <I> test(t: Test<I>) {
+    t.apply(t.<!INAPPLICABLE_CANDIDATE!>foo<!>())
+}
diff --git a/compiler/testData/diagnostics/tests/variance/privateToThis/GetVal.fir.kt b/compiler/testData/diagnostics/tests/variance/privateToThis/GetVal.fir.kt
new file mode 100644
index 00000000000..e5b46746182
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/privateToThis/GetVal.fir.kt
@@ -0,0 +1,37 @@
+fun <T> getT(): T = null!!
+
+class Test<in I, out O> {
+    private val i: I = getT()
+
+    init {
+        apply(i)
+        apply(this.i)
+    }
+
+    fun apply(i: I) {}
+
+    fun test() {
+        apply(i)
+        apply(this.i)
+        with(Test<I, O>()) {
+            apply(i) // resolved to this@Test.i
+            apply(this.i)
+            apply(this@with.i)
+            apply(this@Test.i)
+        }
+    }
+
+    fun <I, O> test(t: Test<I, O>) {
+        t.apply(t.i)
+    }
+
+    companion object {
+        fun <I, O> test(t: Test<I, O>) {
+            t.apply(t.i)
+        }
+    }
+}
+
+fun <I, O> test(t: Test<I, O>) {
+    t.apply(t.<!INAPPLICABLE_CANDIDATE!>i<!>)
+}
diff --git a/compiler/testData/diagnostics/tests/variance/privateToThis/SetVar.fir.kt b/compiler/testData/diagnostics/tests/variance/privateToThis/SetVar.fir.kt
new file mode 100644
index 00000000000..e662794145d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/privateToThis/SetVar.fir.kt
@@ -0,0 +1,37 @@
+fun <T> getT(): T = null!!
+
+class Test<in I, out O> {
+    private var i: I = getT()
+    private val j: I
+
+    init {
+        j = getT()
+        i = getT()
+        this.i = getT()
+    }
+
+    fun test() {
+        i = getT()
+        this.i = getT()
+        with(Test<I, O>()) {
+            i = getT() // resolved to this@Test.i
+            this.i = getT()
+            this@with.i = getT()
+            this@Test.i  = getT()
+        }
+    }
+
+    fun <I, O> test(t: Test<I, O>) {
+        t.i = getT()
+    }
+
+    companion object {
+        fun <I, O> test(t: Test<I, O>) {
+            t.i = getT()
+        }
+    }
+}
+
+fun <I, O> test(t: Test<I, O>) {
+    t.<!INAPPLICABLE_CANDIDATE!>i<!> = getT()
+}
diff --git a/compiler/testData/diagnostics/tests/variance/privateToThis/ValReassigned.fir.kt b/compiler/testData/diagnostics/tests/variance/privateToThis/ValReassigned.fir.kt
new file mode 100644
index 00000000000..486f11c43f1
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/variance/privateToThis/ValReassigned.fir.kt
@@ -0,0 +1,20 @@
+fun <T> getT(): T = null!!
+
+class A<in I>(init: I) {
+    private val i: I
+
+    init {
+        i = getT()
+    }
+
+    private var i2 = i
+    private val i3: I
+
+    private var i4 = getT<I>()
+
+    init {
+        i2 = getT()
+        i3 = init
+        i4 = i3
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromJava.fir.kt b/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromJava.fir.kt
new file mode 100644
index 00000000000..3185bec9eaa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromJava.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +ProhibitInvisibleAbstractMethodsInSuperclasses
+// FILE: base/Base.java
+package base;
+
+public abstract class Base {
+    public void foo() {
+        packagePrivateFoo();
+    }
+
+    /* package-private */ abstract void packagePrivateFoo();
+}
+
+// FILE: Impl.kt
+package impl
+import base.*
+
+class Impl : Base()
+
+fun foo() {
+    Impl().foo()
+}
diff --git a/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromKotlin.fir.kt b/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromKotlin.fir.kt
new file mode 100644
index 00000000000..2c7d6dd65db
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromKotlin.fir.kt
@@ -0,0 +1,47 @@
+// !LANGUAGE: +ProhibitInvisibleAbstractMethodsInSuperclasses
+// MODULE: base
+// FILE: Base.kt
+package base
+
+abstract class Base {
+    fun foo(): String {
+        return internalFoo()
+    }
+    internal abstract fun internalFoo(): String
+}
+
+open class BaseWithOverride : Base() {
+    override fun internalFoo(): String = ""
+}
+
+// MODULE: intermediate(base)
+// FILE: Intermediate.kt
+package intermediate
+import base.*
+
+abstract class Intermediate : Base()
+
+// MODULE: impl(base, intermediate)
+// FILE: Impl.kt
+package impl
+import base.*
+import intermediate.*
+
+class ImplDirectFromBase : Base()
+
+object ImplObjDirectFromBase : Base()
+
+class ImplDirectFromBaseWithOverride : BaseWithOverride()
+
+class ImplDirectFromBaseWithOverrid : Base() {
+    override fun internalFoo(): String = ""
+}
+
+class ImplViaIntermediate : Intermediate()
+
+fun foo() {
+    ImplDirectFromBase().foo()
+    ImplObjDirectFromBase.foo()
+    ImplDirectFromBaseWithOverride().foo()
+    ImplViaIntermediate().foo()
+}
diff --git a/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromKotlinWarning.fir.kt b/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromKotlinWarning.fir.kt
new file mode 100644
index 00000000000..8a09feb8a6f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/visibility/abstractInvisibleMemberFromKotlinWarning.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: -ProhibitInvisibleAbstractMethodsInSuperclasses
+// MODULE: base
+// FILE: Base.kt
+package base
+
+abstract class Base {
+    fun foo(): String {
+        return internalFoo()
+    }
+    internal abstract fun internalFoo(): String
+}
+
+// MODULE: impl(base)
+// FILE: Impl.kt
+package impl
+import base.*
+
+class Impl : Base()
+
+fun foo() {
+    Impl().foo()
+}
diff --git a/compiler/testData/diagnostics/tests/when/AnnotatedWhenStatement.fir.kt b/compiler/testData/diagnostics/tests/when/AnnotatedWhenStatement.fir.kt
new file mode 100644
index 00000000000..cc1c5c9db55
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/AnnotatedWhenStatement.fir.kt
@@ -0,0 +1,8 @@
+fun foo(a: Int) {
+    @ann
+    when (a) {
+        1 -> {}
+    }
+}
+
+annotation class ann
diff --git a/compiler/testData/diagnostics/tests/when/BranchBypassVal.fir.kt b/compiler/testData/diagnostics/tests/when/BranchBypassVal.fir.kt
new file mode 100644
index 00000000000..1fc11675ec2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/BranchBypassVal.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+class A
+
+fun test(a: Any): String {
+    val q: String? = null
+
+    when (a) {
+        is A -> q!!
+    }
+    // When is not exhaustive
+    return q
+}
diff --git a/compiler/testData/diagnostics/tests/when/BranchBypassVar.fir.kt b/compiler/testData/diagnostics/tests/when/BranchBypassVar.fir.kt
new file mode 100644
index 00000000000..7a8e4484cca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/BranchBypassVar.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+class A
+
+fun test(a: Any) {
+    var q: String? = null
+
+    when (a) {
+        is A -> q = "1"
+    }
+    // When is not exhaustive
+    return q
+}
diff --git a/compiler/testData/diagnostics/tests/when/BranchFalseBypass.fir.kt b/compiler/testData/diagnostics/tests/when/BranchFalseBypass.fir.kt
new file mode 100644
index 00000000000..1b406849f6e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/BranchFalseBypass.fir.kt
@@ -0,0 +1,12 @@
+enum class My { A, B }
+
+fun test(a: My): String {
+    val q: String?
+
+    when (a) {
+        My.A -> q = "1"
+        My.B -> q = "2"
+    }
+    // When is exhaustive
+    return q
+}
diff --git a/compiler/testData/diagnostics/tests/when/BranchFalseBypassElse.fir.kt b/compiler/testData/diagnostics/tests/when/BranchFalseBypassElse.fir.kt
new file mode 100644
index 00000000000..c66f5e955aa
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/BranchFalseBypassElse.fir.kt
@@ -0,0 +1,12 @@
+class A
+
+fun test(a: Any): String {
+    var q: String?
+
+    when (a) {
+        is A -> q = "1"
+        else -> q = "2"
+    }
+    // When is not exhaustive
+    return q
+}
diff --git a/compiler/testData/diagnostics/tests/when/CommaInWhenConditionWithoutArgument.fir.kt b/compiler/testData/diagnostics/tests/when/CommaInWhenConditionWithoutArgument.fir.kt
new file mode 100644
index 00000000000..da4a6d4c2a7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/CommaInWhenConditionWithoutArgument.fir.kt
@@ -0,0 +1,11 @@
+fun foo(x: Int, y: Int): Int =
+        when {
+            x > 0, y > 0,<!SYNTAX!>,<!> x < 0 -> 1
+            else -> 0
+        }
+
+fun bar(x: Int): Int =
+        when (x) {
+            0 -> 0
+            else -> 1
+        }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/DuplicatedLabels.fir.kt b/compiler/testData/diagnostics/tests/when/DuplicatedLabels.fir.kt
new file mode 100644
index 00000000000..72d12360fa9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/DuplicatedLabels.fir.kt
@@ -0,0 +1,51 @@
+package test
+
+const val four = 4
+
+fun first(arg: Int) = when (arg) {
+    1 -> 2
+    2 -> 3
+    1 -> 4
+    4 -> 5
+    1 -> 6
+    2 -> 7
+    // Error should be here: see KT-11971
+    four -> 8
+    else -> 0
+}
+
+fun second(arg: String): Int {
+    when (arg) {
+        "ABC" -> return 0
+        "DEF" -> return 1
+        "ABC" -> return -1
+        "DEF" -> return -2
+    }
+    return 42
+}
+
+fun third(arg: Any?): Int {
+    when (arg) {
+        null -> return -1
+        is String -> return 0
+        is Double -> return 1
+        is Double -> return 2
+        null -> return 3
+        else -> return 5
+    }
+}
+
+enum class Color { RED, GREEN, BLUE }
+
+fun fourth(arg: Color) = when (arg) {
+    Color.RED -> "RED"
+    Color.GREEN -> "GREEN"
+    Color.RED -> "BLUE"
+    Color.BLUE -> "BLUE"
+}
+
+fun fifth(arg: Any?) = when (arg) {
+    is Any -> "Any"
+    else -> ""
+    else -> null
+}
diff --git a/compiler/testData/diagnostics/tests/when/ElseOnNullableEnum.fir.kt b/compiler/testData/diagnostics/tests/when/ElseOnNullableEnum.fir.kt
new file mode 100644
index 00000000000..049871ff6bb
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ElseOnNullableEnum.fir.kt
@@ -0,0 +1,46 @@
+// KT-2902 Check for null should be required when match nullable enum element
+
+// FILE: 1.kt
+
+enum class E { A, B }
+
+fun test(e: E?) = when (e) {
+    E.A -> 1
+    E.B -> 2
+}
+
+fun withNull(e: E?) = when (e) {
+    E.A -> 3
+    E.B -> 4
+    null -> null
+}
+
+fun nullableNothing(): Nothing? = null
+fun withNullableNothing(e: E?) = when (e) {
+    E.A -> 5
+    E.B -> 6
+    nullableNothing() -> null
+}
+
+fun platformType() = when (J.foo()) {
+    E.A -> 7
+    E.B -> 8
+}
+
+fun platformTypeSmartCast(): Int {
+    val e = J.foo()
+    if (e == null) return -1
+    return when (e) {
+        E.A -> 1
+        E.B -> 2
+    }
+}
+
+
+// FILE: J.java
+
+class J {
+    static E foo() {
+        return E.A;
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ElseOnNullableEnumWithSmartCast.fir.kt b/compiler/testData/diagnostics/tests/when/ElseOnNullableEnumWithSmartCast.fir.kt
new file mode 100644
index 00000000000..f0f8219837f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ElseOnNullableEnumWithSmartCast.fir.kt
@@ -0,0 +1,11 @@
+enum class E { A, B }
+
+fun foo(e: E, something: Any?): Int {
+    if (something != null) return 0
+
+    return when (e) {
+        E.A -> 1
+        E.B -> 2
+        something -> 3
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/EmptyConditionWithExpression.fir.kt b/compiler/testData/diagnostics/tests/when/EmptyConditionWithExpression.fir.kt
new file mode 100644
index 00000000000..4683fbbb7b2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/EmptyConditionWithExpression.fir.kt
@@ -0,0 +1,8 @@
+// EA-68871: empty when condition
+fun foo(arg: Int): Int {
+    when (arg) {
+        0 -> return 0
+        <!SYNTAX!><!>-> return 4
+        else -> return -1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/EmptyConditionWithExpressionEnum.fir.kt b/compiler/testData/diagnostics/tests/when/EmptyConditionWithExpressionEnum.fir.kt
new file mode 100644
index 00000000000..9746ea53b58
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/EmptyConditionWithExpressionEnum.fir.kt
@@ -0,0 +1,9 @@
+// EA-68871: empty when condition
+enum class My { FIRST, SECOND }
+fun foo(arg: My): Int {
+    when (arg) {
+        My.FIRST -> return 0
+        <!SYNTAX!><!>-> return 4
+        else -> return -1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveBoolean.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveBoolean.fir.kt
new file mode 100644
index 00000000000..fc65d061fce
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveBoolean.fir.kt
@@ -0,0 +1,8 @@
+// See also: KT-3743
+fun foo(arg: Boolean): String {
+    // Must be exhaustive
+    return when(arg) {
+        true -> "truth"
+        false -> "falsehood"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanBrackets.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanBrackets.fir.kt
new file mode 100644
index 00000000000..3ac5e9812b7
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanBrackets.fir.kt
@@ -0,0 +1,7 @@
+fun foo(arg: Boolean): String {
+    // Must be exhaustive
+    return when(arg) {
+        (true) -> "truth"
+        ((false)) -> "falsehood"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanComplex.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanComplex.fir.kt
new file mode 100644
index 00000000000..43d4890652b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanComplex.fir.kt
@@ -0,0 +1,8 @@
+// See also: KT-3743
+fun foo(arg: Boolean): String {
+    // Must be exhaustive
+    return when(arg) {
+        2 == 2 -> "truth"
+        2 == 1 -> "falsehood"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanNullable.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanNullable.fir.kt
new file mode 100644
index 00000000000..dfb530e9641
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveBooleanNullable.fir.kt
@@ -0,0 +1,9 @@
+// See also: KT-3743
+fun foo(arg: Boolean?): String {
+    // Must be exhaustive
+    return when(arg) {
+        true -> "truth"
+        false -> "falsehood"
+        null -> "unknown"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveBreakContinue.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveBreakContinue.fir.kt
new file mode 100644
index 00000000000..8a4910d7564
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveBreakContinue.fir.kt
@@ -0,0 +1,14 @@
+enum class Color { RED, GREEN, BLUE }
+
+fun foo(arr: Array<Color>): Color {
+    loop@ for (color in arr) {
+        when (color) {
+            Color.RED -> return color
+            Color.GREEN -> break@loop
+            Color.BLUE -> if (arr.size == 1) return color else continue@loop
+        }
+        // Unreachable
+        return Color.BLUE
+    }
+    return Color.GREEN
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveEnumIs.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveEnumIs.fir.kt
new file mode 100644
index 00000000000..3c58abd2073
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveEnumIs.fir.kt
@@ -0,0 +1,11 @@
+enum class MyEnum {
+    A, B, C
+}
+
+fun foo(x: MyEnum): Int {
+    return when (x) {
+        is MyEnum.A -> 1
+        is MyEnum.B -> 2
+        is MyEnum.C -> 3
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveEnumMixed.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveEnumMixed.fir.kt
new file mode 100644
index 00000000000..6ff1b9e4ba9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveEnumMixed.fir.kt
@@ -0,0 +1,11 @@
+enum class MyEnum {
+    A, B, C
+}
+
+fun foo(x: MyEnum): Int {
+    return when (x) {
+        MyEnum.A -> 1
+        is MyEnum.B -> 2
+        is MyEnum.C -> 3
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveInitialization.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveInitialization.fir.kt
new file mode 100644
index 00000000000..0e15e5efb3d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveInitialization.fir.kt
@@ -0,0 +1,15 @@
+enum class Direction {
+    NORTH, SOUTH, WEST, EAST
+}
+
+fun foo(dir: Direction): Int {
+    val res: Int
+    // See KT-6046: res is always initialized
+    when (dir) {
+        Direction.NORTH -> res = 1
+        Direction.SOUTH -> res = 2
+        Direction.WEST  -> res = 3
+        Direction.EAST  -> res = 4
+    }
+    return res
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveNoInitialization.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveNoInitialization.fir.kt
new file mode 100644
index 00000000000..b7f68238504
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveNoInitialization.fir.kt
@@ -0,0 +1,11 @@
+fun foo(b: Boolean): Int {
+    val x: Int
+    val y: Int
+    when (b) {
+        true -> y = 1
+        false -> y = 0
+    }
+    // x is initialized here
+    x = 3
+    return x + y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveNullable.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveNullable.fir.kt
new file mode 100644
index 00000000000..19edb89d8fd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveNullable.fir.kt
@@ -0,0 +1,14 @@
+enum class MyEnum {
+    A, B
+}
+
+fun foo(x: MyEnum?): Int {
+    val y: Int
+    // See KT-6046: y is always initialized
+    when (x) {
+        MyEnum.A -> y = 1
+        MyEnum.B -> y = 2
+        null -> y = 0
+    }
+    return y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnum.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnum.fir.kt
new file mode 100644
index 00000000000..2a97dd3827c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnum.fir.kt
@@ -0,0 +1,21 @@
+// See KT-6399: exhaustive whens on platform enums
+
+// FILE: J.java
+
+public enum J {
+    A, B;
+
+    public static J create() {
+        return J.A;
+    }
+}
+
+// FILE: K.kt
+
+fun foo(): Int {
+    // When is exhaustive (count a platform enum as a special case)
+    return when (J.create()) {
+        J.A -> 1
+        J.B -> 2
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumAnnotated.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumAnnotated.fir.kt
new file mode 100644
index 00000000000..6820a883e59
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumAnnotated.fir.kt
@@ -0,0 +1,23 @@
+// See KT-6399: exhaustive whens on platform enums
+
+// FILE: J.java
+
+import org.jetbrains.annotations.*;
+
+public enum J {
+    A, B;
+
+    @NotNull public static J create() {
+        return J.A;
+    }
+}
+
+// FILE: K.kt
+
+fun foo(): Int {
+    // When is exhaustive (count a platform enum as a special case)
+    return when (J.create()) {
+        J.A -> 1
+        J.B -> 2
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumElse.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumElse.fir.kt
new file mode 100644
index 00000000000..bd311096cf2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumElse.fir.kt
@@ -0,0 +1,21 @@
+// See KT-6399: exhaustive whens on platform enums
+
+// FILE: J.java
+
+public enum J {
+    A, B;
+
+    public static J create() {
+        return J.A;
+    }
+}
+
+// FILE: K.kt
+
+fun foo(): Int {
+    return when (J.create()) {
+        J.A -> 1
+        J.B -> 2
+        else -> 0
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumNull.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumNull.fir.kt
new file mode 100644
index 00000000000..c809bee2c2b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumNull.fir.kt
@@ -0,0 +1,22 @@
+// See KT-6399: exhaustive whens on platform enums
+
+// FILE: J.java
+
+public enum J {
+    A, B;
+
+    public static J create() {
+        return J.A;
+    }
+}
+
+// FILE: K.kt
+
+fun foo(): Int {
+    // When is exhaustive including null
+    return when (J.create()) {
+        J.A -> 1
+        J.B -> 2
+        null -> 0
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumStatement.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumStatement.fir.kt
new file mode 100644
index 00000000000..a51fda0cbdd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumStatement.fir.kt
@@ -0,0 +1,20 @@
+// See KT-6399: exhaustive whens on platform enums
+
+// FILE: J.java
+
+public enum J {
+    A, B;
+
+    public static J create() {
+        return J.A;
+    }
+}
+
+// FILE: K.kt
+
+fun foo(): Int {
+    when (J.create()) {
+        J.A -> return 1
+        J.B -> return 2
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveReturn.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveReturn.fir.kt
new file mode 100644
index 00000000000..11c764c8ccd
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveReturn.fir.kt
@@ -0,0 +1,13 @@
+enum class Direction {
+    NORTH, SOUTH, WEST, EAST
+}
+
+fun foo(dir: Direction): Int {
+    when (dir) {
+        Direction.NORTH -> return 1
+        Direction.SOUTH -> return 2
+        Direction.WEST  -> return 3
+        Direction.EAST  -> return 4
+    }
+    // See KT-1882: no return is needed at the end
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveReturnThrow.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveReturnThrow.fir.kt
new file mode 100644
index 00000000000..b6bafbb0de4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveReturnThrow.fir.kt
@@ -0,0 +1,14 @@
+enum class Direction {
+    NORTH, SOUTH, WEST, EAST
+}
+
+fun foo(dir: Direction): Int {
+    when (dir) {
+        Direction.NORTH -> return 1
+        Direction.SOUTH -> throw AssertionError("!!!")
+        Direction.WEST  -> return 3
+        Direction.EAST  -> return 4
+    }
+    // Error: Unreachable code. Return is not required.
+    if (dir == Direction.SOUTH) return 2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveValOverConditionalInit.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveValOverConditionalInit.fir.kt
new file mode 100644
index 00000000000..a1ec917c645
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveValOverConditionalInit.fir.kt
@@ -0,0 +1,22 @@
+fun foo(a: Boolean, b: Boolean): Int {
+    val x: Int
+    if (a) {
+        x = 1
+    }
+    when (b) {
+        true -> x = 2
+        false -> x = 3
+    }
+    return x
+}
+
+fun bar(a: Boolean, b: Boolean): Int {
+    val x: Int
+    if (a) {
+        x = 1
+    }
+    when (b) {
+        false -> x = 3
+    }
+    return x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveVarOverConditionalInit.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveVarOverConditionalInit.fir.kt
new file mode 100644
index 00000000000..17994c2be70
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveVarOverConditionalInit.fir.kt
@@ -0,0 +1,22 @@
+fun foo(a: Boolean, b: Boolean): Int {
+    var x: Int
+    if (a) {
+        x = 1
+    }
+    when (b) {
+        true -> x = 2
+        false -> x = 3
+    }
+    return x
+}
+
+fun bar(a: Boolean, b: Boolean): Int {
+    var x: Int
+    if (a) {
+        x = 1
+    }
+    when (b) {
+        false -> x = 3
+    }
+    return x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheck.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheck.fir.kt
new file mode 100644
index 00000000000..86925b7212a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheck.fir.kt
@@ -0,0 +1,14 @@
+// KT-7857: when exhaustiveness does not take previous nullability checks into account
+enum class X { A, B }
+fun foo(arg: X?): Int {
+    if (arg != null) {
+        return when (arg) {
+            X.A -> 1
+            X.B -> 2
+            // else or null branch should not be required here!
+        }
+    } 
+    else {
+        return 0
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckBefore.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckBefore.fir.kt
new file mode 100644
index 00000000000..41d97447c03
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckBefore.fir.kt
@@ -0,0 +1,12 @@
+// KT-7857: when exhaustiveness does not take previous nullability checks into account
+enum class X { A, B }
+fun foo(arg: X?): Int {
+    if (arg == null) {
+        return 0
+    }
+    return when (arg) {
+        X.A -> 1
+        X.B -> 2
+        // else or null branch should not be required here!
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckBoolean.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckBoolean.fir.kt
new file mode 100644
index 00000000000..67e7e269297
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckBoolean.fir.kt
@@ -0,0 +1,13 @@
+// KT-7857: when exhaustiveness does not take previous nullability checks into account
+fun foo(arg: Boolean?): Int {
+    if (arg != null) {
+        return when (arg) {
+            true -> 1
+            false -> 0
+            // else or null branch should not be required here!
+        }
+    } 
+    else {
+        return -1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckElse.fir.kt b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckElse.fir.kt
new file mode 100644
index 00000000000..3b315600ab8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ExhaustiveWithNullabilityCheckElse.fir.kt
@@ -0,0 +1,14 @@
+// KT-7857: when exhaustiveness does not take previous nullability checks into account
+enum class X { A, B }
+fun foo(arg: X?): Int {
+    if (arg == null) {
+        return 0
+    }
+    else {
+        return when (arg) {
+            X.A -> 1
+            X.B -> 2
+            // else or null branch should not be required here!
+        }
+    } 
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NoElseExpectedUnit.fir.kt b/compiler/testData/diagnostics/tests/when/NoElseExpectedUnit.fir.kt
new file mode 100644
index 00000000000..4b240e601c9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NoElseExpectedUnit.fir.kt
@@ -0,0 +1,7 @@
+fun foo(x: Int) {
+    val y: Unit = when (x) {
+        2 -> {}
+        3 -> {}
+    }
+    return y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NoElseNoExpectedType.fir.kt b/compiler/testData/diagnostics/tests/when/NoElseNoExpectedType.fir.kt
new file mode 100644
index 00000000000..c625fff796e
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NoElseNoExpectedType.fir.kt
@@ -0,0 +1,6 @@
+fun foo(x: Int): Any {
+    val v = when (x) {
+        2 -> 0
+    }
+    return v
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NoElseReturnedCoercionToUnit.fir.kt b/compiler/testData/diagnostics/tests/when/NoElseReturnedCoercionToUnit.fir.kt
new file mode 100644
index 00000000000..695f64ab91c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NoElseReturnedCoercionToUnit.fir.kt
@@ -0,0 +1,11 @@
+fun foo(x: Int) {
+    r {
+        when (x) {
+            2 -> 0
+        }
+    }
+}
+
+fun r(f: () -> Unit) {
+    f()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NoElseReturnedFromLambdaExpectedInt.fir.kt b/compiler/testData/diagnostics/tests/when/NoElseReturnedFromLambdaExpectedInt.fir.kt
new file mode 100644
index 00000000000..4dfb9c7dbcf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NoElseReturnedFromLambdaExpectedInt.fir.kt
@@ -0,0 +1,11 @@
+fun foo(x: Int) {
+    r {
+        when (x) {
+            2 -> 0
+        }
+    }
+}
+
+fun r(f: () -> Int) {
+    f()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NoElseReturnedNonUnit.fir.kt b/compiler/testData/diagnostics/tests/when/NoElseReturnedNonUnit.fir.kt
new file mode 100644
index 00000000000..1ba2b607982
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NoElseReturnedNonUnit.fir.kt
@@ -0,0 +1,5 @@
+fun foo(x: Int): Any {
+    return when (x) {
+        2 -> 0
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NoElseReturnedUnit.fir.kt b/compiler/testData/diagnostics/tests/when/NoElseReturnedUnit.fir.kt
new file mode 100644
index 00000000000..606fe43e816
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NoElseReturnedUnit.fir.kt
@@ -0,0 +1,6 @@
+fun foo(x: Int) {
+    return when (x) {
+        2 -> {}
+        3 -> {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NoElseWhenStatement.fir.kt b/compiler/testData/diagnostics/tests/when/NoElseWhenStatement.fir.kt
new file mode 100644
index 00000000000..000a829fa71
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NoElseWhenStatement.fir.kt
@@ -0,0 +1,6 @@
+fun foo(x: Int) {
+    when (x) {
+        2 -> {}
+        3 -> {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustiveBooleanNullable.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustiveBooleanNullable.fir.kt
new file mode 100644
index 00000000000..a1b0cf6478c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustiveBooleanNullable.fir.kt
@@ -0,0 +1,8 @@
+// See also: KT-3743
+fun foo(arg: Boolean?): String {
+    // Must be NOT exhaustive
+    return when(arg) {
+        true -> "truth"
+        false -> "falsehood"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustivePlatformEnum.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustivePlatformEnum.fir.kt
new file mode 100644
index 00000000000..f88086ef62a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustivePlatformEnum.fir.kt
@@ -0,0 +1,20 @@
+// See KT-6399: exhaustive whens on platform enums
+
+// FILE: J.java
+
+public enum J {
+    A, B;
+
+    public static J create() {
+        return J.A;
+    }
+}
+
+// FILE: K.kt
+
+fun foo(): Int {
+    // When is not-exhaustive
+    return when (J.create()) {
+        J.A -> 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustiveWarning.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarning.fir.kt
new file mode 100644
index 00000000000..311b12aae32
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarning.fir.kt
@@ -0,0 +1,11 @@
+// Base for KT-6227
+enum class X { A, B, C, D }
+
+fun foo(arg: X): String {
+    var res = "XXX"
+    when (arg) {
+        X.A -> res = "A"
+        X.B -> res = "B"
+    }
+    return res
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningElse.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningElse.fir.kt
new file mode 100644
index 00000000000..673943fa385
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningElse.fir.kt
@@ -0,0 +1,12 @@
+// Base for KT-6227
+enum class X { A, B, C, D }
+
+fun foo(arg: X): String {
+    val res: String
+    when (arg) {
+        X.A -> res = "A"
+        X.B -> res = "B"
+        else -> res = "CD"
+    }
+    return res
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningFalse.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningFalse.fir.kt
new file mode 100644
index 00000000000..c78080fd833
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningFalse.fir.kt
@@ -0,0 +1,13 @@
+// Base for KT-6227
+enum class X { A, B, C, D }
+
+fun foo(arg: X): String {
+    val res: String
+    when (arg) {
+        X.A -> res = "A"
+        X.B -> res = "B"
+        X.C -> res = "C"
+        X.D -> res = "D"
+    }
+    return res
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningForSealedClass.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningForSealedClass.fir.kt
new file mode 100644
index 00000000000..36e760226ea
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningForSealedClass.fir.kt
@@ -0,0 +1,16 @@
+sealed class S
+
+object First : S()
+
+class Derived(val s: String) : S()
+
+object Last : S()
+
+fun use(s: String) = s
+
+fun foo(s: S) {
+    when (s) {
+        First -> {}
+        is Derived -> use(s.s)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningNull.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningNull.fir.kt
new file mode 100644
index 00000000000..a71a3c99564
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustiveWarningNull.fir.kt
@@ -0,0 +1,14 @@
+// Base for KT-6227
+enum class X { A, B, C, D }
+
+fun foo(arg: X?): String {
+    var res = "XXX"
+    // Should we report something here? Probably not, null is not an enum entry
+    when (arg) {
+        X.A -> res = "A"
+        X.B -> res = "B"
+        X.C -> res = "C"
+        X.D -> res = "D"
+    }
+    return res
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/NonExhaustiveWithNullabilityCheck.fir.kt b/compiler/testData/diagnostics/tests/when/NonExhaustiveWithNullabilityCheck.fir.kt
new file mode 100644
index 00000000000..97cb1995804
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/NonExhaustiveWithNullabilityCheck.fir.kt
@@ -0,0 +1,12 @@
+// KT-7857: when exhaustiveness does not take previous nullability checks into account
+enum class X { A, B }
+fun foo(arg: X?): Int {
+    if (arg != null) {
+        return when (arg) {
+            X.B -> 2
+        }
+    } 
+    else {
+        return 0
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/PropertyNotInitialized.fir.kt b/compiler/testData/diagnostics/tests/when/PropertyNotInitialized.fir.kt
new file mode 100644
index 00000000000..c286b1e93c3
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/PropertyNotInitialized.fir.kt
@@ -0,0 +1,16 @@
+// See KT-5113
+enum class E {
+    A,
+    B
+}
+
+class Outer(e: E) {
+    private val prop: Int
+    init {
+        when(e ) {
+            // When is exhaustive, property is always initialized
+            E.A -> prop = 1
+            E.B -> prop = 2
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/RedundantElse.fir.kt b/compiler/testData/diagnostics/tests/when/RedundantElse.fir.kt
new file mode 100644
index 00000000000..88d76554d03
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/RedundantElse.fir.kt
@@ -0,0 +1,68 @@
+// FILE: MyEnum.java
+public enum MyEnum {
+    SINGLE;
+
+    public static MyEnum getInstance() {
+        return SINGLE;
+    }
+}
+
+
+// FILE: test.kt
+
+sealed class X {
+    class A : X()
+    class B : X()
+}
+
+fun foo(x: X) = when (x) {
+    is X.A -> {}
+    is X.B -> {}
+    else -> {}
+}
+
+fun bar(x: X?): String = when (x) {
+    is X.A -> "A"
+    is X.B -> "B"
+    null -> "null"
+    else -> "Unreachable"
+}
+
+fun justUse(x: X) {
+    when (x) {
+        is X.A -> {}
+        is X.B -> {}
+        // Redundant even in statement position
+        else -> {}
+    }
+}
+
+enum class E {
+    A, B
+}
+
+fun foo(e: E): String = when (e) {
+    E.A -> "A"
+    E.B -> "B"
+    else -> ""
+}
+
+fun bar(e: E?): String = when (e) {
+    E.A -> "A"
+    E.B -> "B"
+    else -> "" // no warning
+}
+
+fun foo(b: Boolean) = when (b) {
+    true -> 1
+    false -> 0
+    else -> -1
+}
+
+fun useJava(): String {
+    val me = MyEnum.getInstance()
+    return when (me) {
+        MyEnum.SINGLE -> "OK"
+        else -> "FAIL" // no warning
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/ReservedExhaustiveWhen.fir.kt b/compiler/testData/diagnostics/tests/when/ReservedExhaustiveWhen.fir.kt
new file mode 100644
index 00000000000..768ca9e343d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/ReservedExhaustiveWhen.fir.kt
@@ -0,0 +1,37 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+infix fun Any.sealed(a: Any?) {}
+
+val x = 1 sealed when (1) {
+    1 -> 1
+    else -> 2
+}
+
+val x1 = 1 sealed /**/ when (1) {
+    1 -> 1
+    else -> 2
+}
+
+fun foo() {
+    <!UNRESOLVED_REFERENCE!>sealed<!><!SYNTAX!><!> when {
+        else -> {}
+    }
+
+    1 sealed when {
+        else -> {}
+    }
+
+    1 sealed (when {
+        else -> {}
+    })
+
+    1
+    <!UNRESOLVED_REFERENCE!>sealed<!><!SYNTAX!><!> when {
+        else -> {}
+    }
+
+    1 sealed
+    when {
+        else -> {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/TopLevelSealed.fir.kt b/compiler/testData/diagnostics/tests/when/TopLevelSealed.fir.kt
new file mode 100644
index 00000000000..51371115be4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/TopLevelSealed.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+sealed class A {
+    class B: A() {
+        class C: A()
+    }
+}
+
+class D: A()
+
+fun test(a: A) {
+    val nonExhaustive = when (a) {
+        is A.B -> "B"
+        is A.B.C -> "C"
+    }
+
+    val exhaustive = when (a) {
+        is A.B -> "B"
+        is A.B.C -> "C"
+        is D -> "D"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/When.fir.kt b/compiler/testData/diagnostics/tests/when/When.fir.kt
new file mode 100644
index 00000000000..287bc1ea340
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/When.fir.kt
@@ -0,0 +1,46 @@
+// !WITH_NEW_INFERENCE
+fun Int.foo() : Boolean = true
+
+fun foo() : Int {
+    val s = ""
+    val x = 1
+    when (x) {
+      is String -> 1
+      !is Int -> 1
+      is Any? -> 1
+      is Any -> 1
+      s -> 1
+      1 -> 1
+      1 <!AMBIGUITY!>+<!> <!UNRESOLVED_REFERENCE!>a<!> -> 1
+      in 1..<!UNRESOLVED_REFERENCE!>a<!> -> 1
+      !in 1..<!UNRESOLVED_REFERENCE!>a<!> -> 1
+      else -> 1
+    }
+
+    return 0
+}
+
+val _type_test : Int = foo() // this is needed to ensure the inferred return type of foo()
+
+fun test() {
+  val x = 1;
+  val s = "";
+
+  when (x) {
+    s -> 1
+    "" -> 1
+    x -> 1
+    1 -> 1
+  }
+
+  val z = 1
+
+  when (z) {
+    else -> 1
+    1 -> 2
+  }
+
+  when (z) {
+    else -> 1
+  }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/WhenTypeDisjunctions.fir.kt b/compiler/testData/diagnostics/tests/when/WhenTypeDisjunctions.fir.kt
new file mode 100644
index 00000000000..61f82a393b6
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/WhenTypeDisjunctions.fir.kt
@@ -0,0 +1,21 @@
+fun foo(s: Any): String {
+    val x = when (s) {
+        is String -> s
+        is Int -> "$s"
+        else -> return ""
+    }
+
+    val y: String = x // should be Ok
+    return y
+}
+
+fun bar(s: Any): String {
+    val x = when (s) {
+        is String -> s as String // meaningless
+        is Int -> "$s"
+        else -> return ""
+    }
+
+    val y: String = x // no error
+    return y
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/kt10439.fir.kt b/compiler/testData/diagnostics/tests/when/kt10439.fir.kt
new file mode 100644
index 00000000000..fe6325b748a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/kt10439.fir.kt
@@ -0,0 +1,13 @@
+// !WITH_NEW_INFERENCE
+fun foo(x: Int) = x
+
+fun test0(flag: Boolean) {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(if (flag) true else "")
+}
+
+fun test1(flag: Boolean) {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(when (flag) {
+        true -> true
+        else -> ""
+    })
+}
diff --git a/compiler/testData/diagnostics/tests/when/kt10809.fir.kt b/compiler/testData/diagnostics/tests/when/kt10809.fir.kt
new file mode 100644
index 00000000000..3ccd6260110
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/kt10809.fir.kt
@@ -0,0 +1,52 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER -DEBUG_INFO_SMARTCAST
+// NI_EXPECTED_FILE
+
+interface Data
+interface Item
+class FlagData(val value: Boolean) : Data
+class ListData<T : Item>(val list: List<T>) : Data
+
+fun <T> listOf(vararg items: T): List<T> = null!!
+
+fun test1(o: Any) = when (o) {
+    is List<*> ->
+        ListData(listOf())
+    is Int -> when {
+        o < 0 ->
+            FlagData(true)
+        else ->
+            null
+    }
+    else ->
+        null
+}
+
+fun test1x(o: Any): Data? = when (o) {
+    is List<*> ->
+        ListData(listOf())
+    is Int -> when {
+        o < 0 ->
+            FlagData(true)
+        else ->
+            null
+    }
+    else ->
+        null
+}
+
+fun test2() =
+        if (true)
+            ListData(listOf())
+        else
+            FlagData(true)
+
+fun test2x(): Data =
+        if (true) ListData(listOf()) else FlagData(true)
+
+fun test2y(): Any =
+        if (true) ListData(listOf()) else FlagData(true)
+
+fun test2z(): Any =
+        run { if (true) ListData(listOf()) else FlagData(true) }
+
diff --git a/compiler/testData/diagnostics/tests/when/kt10811.fir.kt b/compiler/testData/diagnostics/tests/when/kt10811.fir.kt
new file mode 100644
index 00000000000..e99415e09a4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/kt10811.fir.kt
@@ -0,0 +1,24 @@
+interface Maybe<T>
+class Some<T>(val value: T) : Maybe<T>
+class None<T> : Maybe<T>
+
+fun <T> none() : None<T> = TODO()
+
+fun test1() : Maybe<String?> = if (true) none() else Some("")
+
+fun test2() : Maybe<String?> = when {
+    true -> none()
+    else -> Some("")
+}
+
+fun test3() : Maybe<String?> = when {
+    true -> none()
+    else -> Some<String?>("")
+}
+
+fun test4() : Maybe<String?> {
+    when ("") {
+        "a" -> return none()
+        else -> return Some<String?>("")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/kt4434.fir.kt b/compiler/testData/diagnostics/tests/when/kt4434.fir.kt
new file mode 100644
index 00000000000..2d2809f0b0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/kt4434.fir.kt
@@ -0,0 +1,27 @@
+// KT-4434 Missed diagnostic about else branch in when
+
+package test
+
+fun foo(): Int {
+    val a = "a"
+    return if (a.length > 0) {
+        when (a) {
+            "a" -> 1
+        }
+    }
+    else {
+        3
+    }
+}
+
+fun bar(): Int {
+    val a = "a"
+    if (a.length > 0) {
+        return when (a) {
+            "a" -> 1
+        }
+    }
+    else {
+        return 3
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/kt9929.fir.kt b/compiler/testData/diagnostics/tests/when/kt9929.fir.kt
new file mode 100644
index 00000000000..bdcef146df4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/kt9929.fir.kt
@@ -0,0 +1,10 @@
+// !WITH_NEW_INFERENCE
+val test: Int = if (true) {
+    when (2) {
+        1 -> 1
+        else -> null
+    }
+}
+else {
+    2
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/kt9972.fir.kt b/compiler/testData/diagnostics/tests/when/kt9972.fir.kt
new file mode 100644
index 00000000000..b5265b36f1a
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/kt9972.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+fun test1(): Int {
+    val x: String = if (true) {
+        when {
+            true -> Any()
+            else -> null
+        }
+    } else ""
+    return x.hashCode()
+}
+
+fun test2(): Int {
+    val x: String = when {
+                        true -> Any()
+                        else -> null
+                    } ?: return 0
+    return x.hashCode()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/whenAndLambdaWithExpectedType.fir.kt b/compiler/testData/diagnostics/tests/when/whenAndLambdaWithExpectedType.fir.kt
new file mode 100644
index 00000000000..e82e0a7bae4
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/whenAndLambdaWithExpectedType.fir.kt
@@ -0,0 +1,25 @@
+// !WITH_NEW_INFERENCE
+val test1: (String) -> Boolean =
+        when {
+            true -> {{ true }}
+            else -> {{ false }}
+        }
+
+val test2: (String) -> Boolean =
+        when {
+            true -> {{ true }}
+            else -> null!!
+        }
+
+val test3: (String) -> Boolean =
+        when {
+            true -> { s -> true }
+            else -> null!!
+        }
+
+val test4: (String) -> Boolean =
+        when {
+            true -> { s1, s2 -> true }
+            else -> null!!
+        }
+
diff --git a/compiler/testData/diagnostics/tests/when/whenWithNothingAndLambdas.fir.kt b/compiler/testData/diagnostics/tests/when/whenWithNothingAndLambdas.fir.kt
new file mode 100644
index 00000000000..ecdc4aeaa90
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/whenWithNothingAndLambdas.fir.kt
@@ -0,0 +1,39 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+val test1 = when {
+    true -> { { true } }
+    else -> TODO()
+}
+
+val test1a: () -> Boolean = when {
+    true -> { { true } }
+    else -> TODO()
+}
+
+val test2 = when {
+    true -> { { true } }
+    else -> when {
+        true -> { { true } }
+        else -> TODO()
+    }
+}
+
+val test2a: () -> Boolean = when {
+    true -> { { true } }
+    else -> when {
+        true -> { { true } } // TODO
+        else -> TODO()
+    }
+}
+
+val test3 = when {
+    true -> { { true } }
+    true -> { { true } }
+    else -> TODO()
+}
+
+val test3a: () -> Boolean = when {
+    true -> { { true } }
+    true -> { { true } }
+    else -> TODO()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/capturingInInitializer.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/capturingInInitializer.fir.kt
new file mode 100644
index 00000000000..ef0abfe66e9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/capturingInInitializer.fir.kt
@@ -0,0 +1,37 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun getBoolean() = true
+
+fun testSafeCaptureVarInInitializer() {
+    var x: Int? = 42
+    x!!
+    x.inc()
+
+    val s = when (val y = run { x = 42; 32 }) {
+        0 -> {
+            x.inc() // TODO fix smart casts for captured variables
+            "0"
+        }
+        else -> "!= 0"
+    }
+
+    x.inc() // TODO fix smart casts for captured variables
+}
+
+
+fun testUnsafeCaptureVarInInitializer() {
+    var x: Int? = 42
+    x!!
+    x.inc()
+
+    val s = when (val y = run { x = null; 32 }) {
+        0 -> {
+            x.<!UNRESOLVED_REFERENCE!>inc<!>() // NB smart cast should be impossible
+            "0"
+        }
+        else -> "!= 0"
+    }
+
+    x.<!UNRESOLVED_REFERENCE!>inc<!>() // NB smart cast should be impossible
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/invisibleOutsideOfWhen.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/invisibleOutsideOfWhen.fir.kt
new file mode 100644
index 00000000000..43f33af1a4b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/invisibleOutsideOfWhen.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun foo(): Any = 42
+
+fun test(x: Any) {
+    val z1 = when (val y = foo()) {
+        42 -> "Magic: $y, $x"
+        else -> {
+            "Not magic: $y, $x"
+        }
+    }
+    val z2 = "Anyway, it was $<!UNRESOLVED_REFERENCE!>y<!>"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/jumpoutInInitializer.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/jumpoutInInitializer.fir.kt
new file mode 100644
index 00000000000..e6b6b7894f2
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/jumpoutInInitializer.fir.kt
@@ -0,0 +1,43 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+
+fun testJumpOutInElvis(x: Int?) {
+    loop@ while (true) {
+        val y = when (val z = x ?: break@loop) {
+            0 -> "0"
+            else -> "not 0"
+        }
+
+        x.inc()
+    }
+
+    x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+}
+
+fun testJumpOutInElvisLikeIf(x: Int?) {
+    loop@ while (true) {
+        val y = when (val z = if (x == null) break@loop else x) {
+            0 -> "0"
+            else -> "not 0"
+        }
+        x.inc()
+    }
+
+    x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+}
+
+
+fun getBoolean() = true
+
+fun testJumpOutInIf(x: Int?) {
+    loop@ while (true) {
+        val y = when (val z = if (getBoolean()) { x!!; break@loop } else x) {
+            0 -> "0"
+            else -> "not 0"
+        }
+        x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+    }
+
+    x.inc() // Actually, safe, but it's OK if it's error
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/nestedWhenWithSubject.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/nestedWhenWithSubject.fir.kt
new file mode 100644
index 00000000000..1be42fe50ee
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/nestedWhenWithSubject.fir.kt
@@ -0,0 +1,41 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -UNUSED_VALUE
+
+fun foo() {}
+fun <T> bar(x: T, y: T) {}
+
+fun test1() {
+    when (1) {
+        1 ->
+            when (val y = 2) {
+                2 -> foo()
+            }
+    }
+}
+
+fun test2() {
+    when (val x = 1) {
+        1 ->
+            when (val y = 2) {
+                2 -> foo()
+            }
+    }
+}
+
+fun test3() {
+    when (val x = 1) {
+        1 ->
+            when (val x = 2) {
+                2 -> foo()
+            }
+    }
+}
+
+fun test4() {
+    when (val x = 1) {
+        1 ->
+            when (val y = 2) {
+                2 -> bar(x, y)
+            }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/noSubjectVariableName.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/noSubjectVariableName.fir.kt
new file mode 100644
index 00000000000..82c12f2fa0d
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/noSubjectVariableName.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+
+fun testNoSubjectVariableName(x: Int?) {
+    val y = when (val<!SYNTAX!><!> = 42) {
+        0 -> "0"
+        else -> "not 0"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/reassignmentToWhenSubjectVariable.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/reassignmentToWhenSubjectVariable.fir.kt
new file mode 100644
index 00000000000..f3aea651833
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/reassignmentToWhenSubjectVariable.fir.kt
@@ -0,0 +1,10 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER -UNUSED_VALUE
+
+fun foo(): Any = 42
+
+fun test1(x: Any) {
+    when (val y = foo()) {
+        is String -> y = ""
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/shadowingOtherVariable.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/shadowingOtherVariable.fir.kt
new file mode 100644
index 00000000000..f5da5eda4d9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/shadowingOtherVariable.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+fun foo(): Any = 42
+fun useInt(i: Int) {}
+
+fun testShadowingParameter(y: Any) {
+    when (val y = foo()) {
+        else -> {}
+    }
+}
+
+fun testShadowedInWhenBody(x: Any) {
+    when (val y = x) {
+        is String -> {
+            val y = y.length
+            useInt(y)
+        }
+    }
+}
+
+fun testShadowinLocalVariable() {
+    val y = foo()
+    when (val y = foo()) {
+        else -> {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartCastOnValueBoundToSubjectVariable.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartCastOnValueBoundToSubjectVariable.fir.kt
new file mode 100644
index 00000000000..c93e8c1f329
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartCastOnValueBoundToSubjectVariable.fir.kt
@@ -0,0 +1,49 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !WITH_NEW_INFERENCE
+
+fun foo(s1: Int, s2: Int) = s1 + s2
+
+fun test1(x: String?) =
+    when (val y = x?.length) {
+        null -> 0
+        else -> foo(x.length, y)
+    }
+
+fun test2(x: String?) {
+    when (val y = run { x!! }) {
+        "foo" -> x.length
+        "bar" -> y.length
+    }
+}
+
+fun test3(x: String?, y: String?) {
+    when (val z = x ?: y!!) {
+        "foo" -> x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        "bar" -> y.<!INAPPLICABLE_CANDIDATE!>length<!>
+        "baz" -> z.length
+    }
+}
+
+fun <T> id(x: T): T = x
+
+fun test4(x: String?) {
+    when (val y = id(x!!)) {
+        "foo" -> x.length
+        "bar" -> y.length
+    }
+}
+
+class Inv<T>(val data: T)
+
+fun test5(x: Inv<out Any?>) {
+    when (val y = x.data) {
+        is String -> y.length // should be ok
+        null -> x.data.<!UNRESOLVED_REFERENCE!>length<!> // should be error
+    }
+}
+
+fun test6(x: Inv<out String?>) {
+    when (val y = x.data) {
+        is String -> x.data.length // should be ok
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartCastsOnSubjectVariable.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartCastsOnSubjectVariable.fir.kt
new file mode 100644
index 00000000000..36c367905cf
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartCastsOnSubjectVariable.fir.kt
@@ -0,0 +1,8 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+
+fun test(x: Any?) =
+        when (val y = x) {
+            is String -> "String, length = ${y.length}"
+            null -> "Null"
+            else -> "Any, hashCode = ${y.hashCode()}"
+        }
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartcastToEnum.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartcastToEnum.fir.kt
new file mode 100644
index 00000000000..882e2c17b76
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartcastToEnum.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+enum class E { FIRST, SECOND }
+
+fun testSmartcastToEnumInSubjectInitializer1(e: E?) {
+    val x1 = when (val ne = e!!) {
+        E.FIRST -> "f"
+        E.SECOND -> "s"
+    }
+}
+
+fun testSmartcastToEnumInSubjectInitializer2(e: E?) {
+    val x2 = when (val ne: Any = e!!) { // NB explicit type annotation
+        E.FIRST -> "f"
+        E.SECOND -> "s"
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartcastToSealed.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartcastToSealed.fir.kt
new file mode 100644
index 00000000000..7e66946fe0b
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/smartcastToSealed.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+sealed class Either
+class Left : Either()
+class Right : Either()
+
+fun testSmartcastToSealedInSubjectInitializer1(x: Any?) {
+    val y1 = when (val either = x as Either) {
+        is Left -> "L"
+        is Right -> "R"
+    }
+}
+
+fun testSmartcastToSealedInSubjectInitializer2(x: Any?) {
+    val y2 = when (val either: Any = x as Either) { // NB explicit type annotation
+        is Left -> "L"
+        is Right -> "R"
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/softModifierName.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/softModifierName.fir.kt
new file mode 100644
index 00000000000..0e554ba12f9
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/softModifierName.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+
+fun test(data: String) =
+    when (data.length) {
+        0 -> -1
+        else -> 42
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/subjectVariableInIsPattern.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/subjectVariableInIsPattern.fir.kt
new file mode 100644
index 00000000000..ed1765401ca
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/subjectVariableInIsPattern.fir.kt
@@ -0,0 +1,8 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+fun test(x: Any) {
+    when (val y = x) {
+        is String -> {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/unsupportedFeature.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/unsupportedFeature.fir.kt
new file mode 100644
index 00000000000..8790b260a15
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/unsupportedFeature.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: -VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun foo(): Any = 42
+
+fun test(x: Any) {
+    // NB check that we still resolve 'y', even though current language version doesn' support variable declaration in when subject
+
+    val z1 = when (val y = foo()) {
+        42 -> "Magic: $y, $x"
+        else -> {
+            "Not magic: $y, $x"
+        }
+    }
+    val z2 = "Anyway, it was $<!UNRESOLVED_REFERENCE!>y<!>"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/unsupportedVariableDeclarationsInWhenSubject.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/unsupportedVariableDeclarationsInWhenSubject.fir.kt
new file mode 100644
index 00000000000..6268016b679
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/unsupportedVariableDeclarationsInWhenSubject.fir.kt
@@ -0,0 +1,29 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// WITH_RUNTIME
+
+fun foo(): Any = 42
+fun String.bar(): Any = 42
+
+
+fun testSimpleValInWhenSubject() {
+    when (val y = foo()) {
+    }
+}
+
+fun testValWithoutInitializerWhenSubject() {
+    when (val y: Any) {
+        is String -> y.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun testVarInWhenSubject() {
+    when (var y = foo()) {
+        is String -> y.length
+    }
+}
+
+fun testDelegatedValInWhenSubject() {
+    when (val y by lazy { 42 }) {
+    }
+}
diff --git a/compiler/testData/diagnostics/tests/when/withSubjectVariable/unusedWhenSubjectVariable.fir.kt b/compiler/testData/diagnostics/tests/when/withSubjectVariable/unusedWhenSubjectVariable.fir.kt
new file mode 100644
index 00000000000..88cfdd3aa77
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/when/withSubjectVariable/unusedWhenSubjectVariable.fir.kt
@@ -0,0 +1,8 @@
+// !LANGUAGE: +VariableDeclarationInWhenSubject
+
+fun foo(): Any = 42
+
+fun test() {
+    when (val x = foo()) {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/ArrayOfNothing.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/ArrayOfNothing.fir.kt
new file mode 100644
index 00000000000..5965caa70c1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/ArrayOfNothing.fir.kt
@@ -0,0 +1,55 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE -UNCHECKED_CAST -USELESS_CAST
+// !LANGUAGE: +ProhibitNonReifiedArraysAsReifiedTypeArguments
+class A<T>
+
+fun test1(
+    a: Array<Nothing>,
+    b: Array<Nothing?>,
+    c: Array<in Nothing>,
+    d: Array<in Nothing?>,
+    e: Array<out Nothing>,
+    f: Array<out Nothing?>
+) {}
+
+fun test2(
+    a: Array<Nothing>?,
+    b: Array<Nothing?>?,
+    c: Array<in Nothing>?,
+    d: Array<in Nothing?>?,
+    e: Array<out Nothing>?,
+    f: Array<out Nothing?>?
+) {}
+
+fun test3(
+    a: A<Array<Nothing>>,
+    b: A<Array<Nothing?>>,
+    c: A<Array<in Nothing>>,
+    d: A<Array<in Nothing?>>,
+    e: A<Array<out Nothing>>,
+    f: A<Array<out Nothing?>>
+) {}
+
+fun test4(
+    a: Array<A<Nothing>>,
+    b: Array<A<Nothing?>>,
+    c: Array<A<in Nothing>>,
+    d: Array<A<in Nothing?>>,
+    e: Array<A<out Nothing>>,
+    f: Array<A<out Nothing?>>
+) {}
+
+fun test5() {
+    arrayOf<Nothing>()
+    Array<Nothing>(10) { throw Exception() }
+}
+
+fun <T> foo(): Array<T> = (object {} as Any) as Array<T>
+
+fun test6() = foo<Nothing>()
+
+
+class B<T>(val array: Array<T>)
+
+fun <T> bar() = B<Array<T>>(arrayOf())
+
+fun test7() = bar<Nothing>()
diff --git a/compiler/testData/diagnostics/testsWithStdLib/CallCompanionProtectedNonStatic.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/CallCompanionProtectedNonStatic.fir.kt
new file mode 100644
index 00000000000..a59b160ba0e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/CallCompanionProtectedNonStatic.fir.kt
@@ -0,0 +1,93 @@
+open class VeryBase {
+    protected fun baz() {}
+}
+
+open class Base {
+    protected fun foo() { 
+        bar() // Ok
+        <!UNRESOLVED_REFERENCE!>baz<!>() // Ok
+    }
+
+    inner class Inner {
+        fun fromInner() {
+            foo() // Ok
+            bar() // Ok
+            gav() // Ok
+            <!UNRESOLVED_REFERENCE!>baz<!>() // Ok
+        }
+    }
+
+    class NestedDerived : Base() {
+        fun fromNestedDerived() {
+            foo() // Ok
+            bar() // Ok
+            gav() // Ok
+            <!UNRESOLVED_REFERENCE!>baz<!>() // Ok
+        }
+    }
+    
+    companion object : VeryBase() {
+        var prop = 42
+            protected set
+
+        protected fun bar() {}
+
+        @JvmStatic protected fun gav() {}       
+
+        class Nested {
+            fun fromNested() {
+                bar() // Ok
+                gav() // Ok
+            }
+        }
+    }
+}
+
+class Derived : Base() {
+    fun test() {
+        foo() // Ok
+        <!INAPPLICABLE_CANDIDATE!>gav<!>() // Ok
+        <!INAPPLICABLE_CANDIDATE!>bar<!>()
+        <!UNRESOLVED_REFERENCE!>baz<!>()
+        prop = 0
+    }
+
+    inner class DerivedInner {
+        fun fromDerivedInner() {
+            foo() // Ok
+            <!INAPPLICABLE_CANDIDATE!>gav<!>() // Ok
+            <!INAPPLICABLE_CANDIDATE!>bar<!>()
+            <!UNRESOLVED_REFERENCE!>baz<!>()
+            prop = 0
+        }
+    }
+
+    companion object {
+        fun test2() {
+            <!INAPPLICABLE_CANDIDATE!>gav<!>() // Ok
+            <!INAPPLICABLE_CANDIDATE!>bar<!>()
+            <!UNRESOLVED_REFERENCE!>baz<!>()
+            prop = 0
+        }
+    }
+}
+
+class Other {
+    fun test(base: Base, derived: Derived) {
+        base.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+        base.<!UNRESOLVED_REFERENCE!>gav<!>()
+        base.<!UNRESOLVED_REFERENCE!>bar<!>()
+        derived.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+        derived.<!UNRESOLVED_REFERENCE!>gav<!>()
+        derived.<!UNRESOLVED_REFERENCE!>bar<!>()
+    }
+}
+
+fun top(base: Base, derived: Derived) {
+    base.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    base.<!UNRESOLVED_REFERENCE!>bar<!>()
+    base.<!UNRESOLVED_REFERENCE!>gav<!>()
+    derived.<!INAPPLICABLE_CANDIDATE!>foo<!>()
+    derived.<!UNRESOLVED_REFERENCE!>bar<!>()
+    derived.<!UNRESOLVED_REFERENCE!>gav<!>()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/CallToMainRedeclaredInMultiFile.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/CallToMainRedeclaredInMultiFile.fir.kt
new file mode 100644
index 00000000000..93682b82053
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/CallToMainRedeclaredInMultiFile.fir.kt
@@ -0,0 +1,8 @@
+// FILE: a.kt
+fun main(args: Array<String>) {}
+
+// FILE: b.kt
+fun main(args: Array<String>) {}
+
+// FILE: c.kt
+fun foo() { main(arrayOf("a", "b")) }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/InaccessibleInternalClass.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/InaccessibleInternalClass.fir.kt
new file mode 100644
index 00000000000..66c2c487bc3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/InaccessibleInternalClass.fir.kt
@@ -0,0 +1,15 @@
+// FILE: a.kt
+package p
+
+class FilteringSequence
+
+// FILE: b.kt
+// SKIP_TXT
+package kotlin.sequences
+
+import p.*
+
+interface I {
+    val v1: FilteringSequence
+    val v2: IndexingSequence<String>
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/PropertyDelegateWithPrivateSet.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/PropertyDelegateWithPrivateSet.fir.kt
new file mode 100644
index 00000000000..9c108459050
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/PropertyDelegateWithPrivateSet.fir.kt
@@ -0,0 +1,12 @@
+// See KT-10107: 'Variable must be initialized' for delegate with private set
+
+class My {
+    var delegate: String by kotlin.properties.Delegates.notNull()
+        private set
+
+    // Error: Variable 'delegate' must be initialized
+    val another: String = delegate
+
+    var delegateWithBackingField: String by kotlin.properties.Delegates.notNull()
+        private set(arg) { field = arg }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/RedeclarationMainInMultiFileClass.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/RedeclarationMainInMultiFileClass.fir.kt
new file mode 100644
index 00000000000..d05cddfe00b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/RedeclarationMainInMultiFileClass.fir.kt
@@ -0,0 +1,11 @@
+// FILE: a.kt
+@file:JvmName("Util")
+@file:JvmMultifileClass
+
+fun main() {}
+
+// FILE: b.kt
+@file:JvmName("Util")
+@file:JvmMultifileClass
+
+fun main() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/RenameOnImportHidesDefaultImport.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/RenameOnImportHidesDefaultImport.fir.kt
new file mode 100644
index 00000000000..fa01f93f89c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/RenameOnImportHidesDefaultImport.fir.kt
@@ -0,0 +1,9 @@
+import kotlin.collections.map as map1
+import kotlin.Array as KotlinArray
+
+fun f() {
+    listOf(1).map1 { it.hashCode() }
+    listOf(1).map { it.hashCode() }
+}
+
+fun g(a1: KotlinArray<Int>, a2: Array<Int>){}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/addAllProjection.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/addAllProjection.fir.kt
new file mode 100644
index 00000000000..1e5d8fbe0f5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/addAllProjection.fir.kt
@@ -0,0 +1,15 @@
+// !WITH_NEW_INFERENCE
+
+fun test(mc: MutableCollection<out CharSequence>) {
+    mc.addAll(mc)
+
+    mc.addAll(arrayListOf<CharSequence>())
+    mc.addAll(arrayListOf())
+
+    mc.addAll(listOf(""))
+    mc.addAll(listOf<String>(""))
+    mc.addAll(listOf<CharSequence>(""))
+
+    mc.addAll(emptyList())
+    mc.addAll(emptyList<Nothing>())
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/ClassObjectAnnotatedWithItsKClass.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/ClassObjectAnnotatedWithItsKClass.fir.kt
new file mode 100644
index 00000000000..013dac39c06
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/ClassObjectAnnotatedWithItsKClass.fir.kt
@@ -0,0 +1,12 @@
+package test
+import kotlin.reflect.KClass
+
+annotation class AnnClass(val a: KClass<*>)
+
+class MyClass {
+
+    @AnnClass(MyClass::class)
+    companion object {
+    }
+
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/JvmSyntheticOnDelegate.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/JvmSyntheticOnDelegate.fir.kt
new file mode 100644
index 00000000000..d5260c2165e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/JvmSyntheticOnDelegate.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_ANONYMOUS_PARAMETER
+import kotlin.properties.Delegates
+
+class My {
+    @delegate:JvmSynthetic val s: String by lazy { "s" }
+
+    // Both Ok
+    @get:JvmSynthetic val t: String by lazy { "t" }
+    @set:JvmSynthetic var z: String by Delegates.observable("?") { prop, old, new -> old.hashCode() }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/Synchronized.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/Synchronized.fir.kt
new file mode 100644
index 00000000000..cf98d083a93
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/Synchronized.fir.kt
@@ -0,0 +1,31 @@
+import kotlin.jvm.Synchronized
+
+interface My {
+    @Synchronized fun foo()
+
+    @Synchronized fun bar() = 1
+
+    @Synchronized fun baz(): String {
+        return "abc"
+    }
+
+    var v: String
+        @Synchronized get() = ""
+        @Synchronized set(value) {}
+}
+
+abstract class Your {
+    @Synchronized abstract fun foo()
+
+    @Synchronized fun bar() = 1
+
+    @Synchronized open fun baz(): String {
+        return "xyz"
+    }
+
+    var v: String
+        @Synchronized get() = ""
+        @Synchronized set(value) {}
+}
+
+@Synchronized fun gav() = 1
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/SynchronizedOnInterfaceCompanionMember.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/SynchronizedOnInterfaceCompanionMember.fir.kt
new file mode 100644
index 00000000000..e2daa315cee
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/SynchronizedOnInterfaceCompanionMember.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !LANGUAGE: +JvmStaticInInterface
+// !JVM_TARGET: 1.8
+
+interface I {
+    companion object {
+        @Synchronized fun syncFun() {}
+
+        @Synchronized @JvmStatic fun syncFunJvmStatic() {}
+
+        var syncProp: String
+            @Synchronized get() = ""
+            @Synchronized set(value) {}
+
+        @JvmStatic var syncPropJvmStatic: String
+            @Synchronized get() = ""
+            @Synchronized set(value) {}
+
+        var syncPropJvmStaticAccessors: String
+            @Synchronized @JvmStatic get() = ""
+            @Synchronized @JvmStatic set(value) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/TransientOnDelegate.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/TransientOnDelegate.fir.kt
new file mode 100644
index 00000000000..30742ed854c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/TransientOnDelegate.fir.kt
@@ -0,0 +1,5 @@
+class C {
+    val plainField: Int = 1
+    @delegate:Transient
+    val lazy by lazy { 1 }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/Volatile.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/Volatile.fir.kt
new file mode 100644
index 00000000000..2d571e84c78
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/Volatile.fir.kt
@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_ANONYMOUS_PARAMETER
+import kotlin.jvm.Volatile
+import kotlin.properties.Delegates
+
+class My {
+    @Volatile val x = 0
+    // ok
+    @Volatile var y = 1
+
+    @delegate:Volatile var z: String by Delegates.observable("?") { prop, old, new -> old.hashCode() }
+
+    @field:Volatile val w = 2
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/annotationsOnUseSiteTargets.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/annotationsOnUseSiteTargets.fir.kt
new file mode 100644
index 00000000000..5605a746d7e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/annotationsOnUseSiteTargets.fir.kt
@@ -0,0 +1,13 @@
+interface Test {
+    @get:JvmStatic
+    val a: Int
+
+    @get:JvmName("1")
+    val b: Int
+
+    @get:Synchronized
+    val c: Int
+
+    @get:JvmOverloads
+    val d: Int
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/illegalPlatformName.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/illegalPlatformName.fir.kt
new file mode 100644
index 00000000000..72762f42829
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/illegalPlatformName.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@JvmName("")
+fun foo(a: Any) {}
+
+@JvmName(".")
+fun foo() {}
+
+@JvmName("/")
+fun fooSlash() {}
+
+@JvmName("<")
+fun fooLT() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/jvmName.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/jvmName.fir.kt
new file mode 100644
index 00000000000..2549e6fa027
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/jvmName.fir.kt
@@ -0,0 +1,95 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+@JvmName("a")
+fun foo() {}
+
+@JvmName("b")
+fun Any.foo() {}
+
+@JvmName("c")
+val px = 1
+
+@JvmName("d")
+val Any.px : Int
+    get() = 1
+
+val valx: Int
+    @JvmName("e")
+    get() = 1
+
+var varx: Int
+    @JvmName("f")
+    get() = 1
+    @JvmName("g")
+    set(v) {}
+
+var vardef: Int = 1
+    @JvmName("h")
+    get
+    @JvmName("i")
+    set
+
+@JvmName("C")
+class C @JvmName("primary") constructor() {
+    @JvmName("ctr") constructor(x: Int): this() {}
+
+    @JvmName("a")
+    fun foo() {}
+
+    @JvmName("b")
+    fun Any.foo() {}
+
+    @JvmName("c")
+    val px = 1
+
+    @JvmName("d")
+    val Any.px : Int
+    get() = 1
+
+    val valx: Int
+    @JvmName("e")
+    get() = 1
+
+    var varx: Int
+    @JvmName("f")
+    get() = 1
+    @JvmName("g")
+    set(v) {}
+}
+
+fun foo1() {
+    @JvmName("a")
+    fun foo() {}
+
+    @JvmName("a")
+    val x = 1
+}
+
+abstract class AB {
+    @JvmName("AB_absFun1")
+    abstract fun absFun1()
+
+    abstract fun absFun2()
+
+    @JvmName("AB_openFun")
+    open fun openFun() {}
+}
+
+class D: AB() {
+    override fun absFun1() {}
+
+    @JvmName("D_absFun2")
+    override fun absFun2() {}
+
+    @JvmName("D_openFun")
+    final override fun openFun() {}
+
+    @JvmName("D_finalFun")
+    fun finalFun() {}
+}
+
+interface Intf {
+    @get:JvmName("getBar") // no error in IDE
+    @set:JvmName("setBar") // no error in IDE
+    var foo: Int
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/jvmNameOnMangledNames.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/jvmNameOnMangledNames.fir.kt
new file mode 100644
index 00000000000..1a4c64ebb53
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/jvmNameOnMangledNames.fir.kt
@@ -0,0 +1,13 @@
+// !LANGUAGE: +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+inline class Foo(val x: Int) {
+    @JvmName("other")
+    fun simple() {}
+}
+
+@JvmName("bad")
+fun bar(f: Foo) {}
+
+@JvmName("good")
+fun baz(r: Result<Int>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/multifileClassPart.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/multifileClassPart.fir.kt
new file mode 100644
index 00000000000..14886ffb509
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/multifileClassPart.fir.kt
@@ -0,0 +1,19 @@
+@file:JvmName("MultifileClass")
+@file:JvmMultifileClass
+@file:FileAnn
+@file:FileBinaryAnn
+@file:FileSourceAnn
+
+@Target(AnnotationTarget.FILE)
+@Retention(AnnotationRetention.RUNTIME)
+public annotation class FileAnn
+
+@Target(AnnotationTarget.FILE)
+@Retention(AnnotationRetention.BINARY)
+public annotation class FileBinaryAnn
+
+@Target(AnnotationTarget.FILE)
+@Retention(AnnotationRetention.SOURCE)
+public annotation class FileSourceAnn
+
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/multifileClassPartWithJavaAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/multifileClassPartWithJavaAnnotation.fir.kt
new file mode 100644
index 00000000000..582be7c2473
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/multifileClassPartWithJavaAnnotation.fir.kt
@@ -0,0 +1,40 @@
+// FILE: test.kt
+@file:JvmName("MultifileClass")
+@file:JvmMultifileClass
+@file:JavaAnn
+@file:JavaClassAnn
+@file:JavaSourceAnn
+
+// FILE: JavaAnn.java
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface JavaAnn {
+}
+
+// FILE: JavaClassAnn.java
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.CLASS)
+public @interface JavaClassAnn {
+}
+
+// FILE: JavaSourceAnn.java
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.SOURCE)
+public @interface JavaSourceAnn {
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/suppressOnFunctionReference.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/suppressOnFunctionReference.fir.kt
new file mode 100644
index 00000000000..eebe8baba18
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationApplicability/suppressOnFunctionReference.fir.kt
@@ -0,0 +1,4 @@
+// !WITH_NEW_INFERENCE
+// See KT-15839
+
+val x = "1".let(@Suppress("DEPRECATION") Integer::parseInt)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/array.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/array.fir.kt
new file mode 100644
index 00000000000..37d863e9cb7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/array.fir.kt
@@ -0,0 +1,24 @@
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Ann(val i: IntArray)
+
+@Ann(intArrayOf(i))
+@Ann(intArrayOf(i2))
+@Ann(intArrayOf(i3))
+@Ann(intArrayOf(i, i2, i3))
+@Ann(<!INAPPLICABLE_CANDIDATE!>intArrayOf<!>(intArrayOf(i, i2, i3)))
+class Test
+
+var i = 1
+const val i2 = 1
+val i3 = foo()
+
+fun foo(): Int = 1
+
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class AnnAnn(val i: Array<Ann>)
+@AnnAnn(arrayOf(Ann(intArrayOf(1))))
+@AnnAnn(arrayOf(iAnn))
+class TestAnn
+val iAnn = Ann(intArrayOf(1))
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/simple.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/simple.fir.kt
new file mode 100644
index 00000000000..d380508fa01
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/simple.fir.kt
@@ -0,0 +1,30 @@
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Ann(val i: Int)
+annotation class AnnIA(val ia: IntArray)
+annotation class AnnSA(val sa: Array<String>)
+
+@Ann(MyClass().i)
+@Ann(i)
+@Ann(i2)
+@AnnIA(ia)
+@AnnSA(sa)
+class Test {
+    val i = 1
+    @Ann(i) val i2 = 1
+}
+
+var i = 1
+val i2 = foo()
+
+fun foo(): Int = 1
+
+@AnnSA(emptyArray())
+class MyClass {
+    val i = 1
+}
+
+val ia: IntArray = intArrayOf(1, 2)
+val sa: Array<String> = arrayOf("a", "b")
+
+annotation class Ann2
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/useOfNonConstVal.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/useOfNonConstVal.fir.kt
new file mode 100644
index 00000000000..469e224f7a9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/useOfNonConstVal.fir.kt
@@ -0,0 +1,16 @@
+val nonConst = 1
+
+const val constConst = nonConst * nonConst + 2
+
+annotation class Ann(val x: Int, val y: String)
+
+@Ann(nonConst, "${nonConst}")
+fun foo1() {}
+
+@Ann(nonConst + constConst, "${constConst}")
+fun foo2() {}
+
+annotation class ArrayAnn(val x: IntArray)
+
+@ArrayAnn(intArrayOf(1, constConst, nonConst))
+fun foo3() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/vararg.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/vararg.fir.kt
new file mode 100644
index 00000000000..12305a83376
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameterMustBeConstant/vararg.fir.kt
@@ -0,0 +1,27 @@
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class Ann(vararg val i: Int)
+
+@Ann(i)
+@Ann(i2)
+@Ann(i3)
+@Ann(i, i2, i3)
+@Ann(*intArrayOf(i))
+@Ann(*intArrayOf(i2))
+@Ann(*intArrayOf(i3))
+@Ann(*intArrayOf(i, i2, i3))
+class Test
+
+var i = 1
+const val i2 = 1
+val i3 = foo()
+
+fun foo(): Int = 1
+
+@Retention(AnnotationRetention.SOURCE)
+@Repeatable
+annotation class AnnAnn(vararg val i: Ann)
+@AnnAnn(*arrayOf(Ann(1)))
+@AnnAnn(*arrayOf(iAnn))
+class TestAnn
+val iAnn = Ann(1)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/kt10136.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/kt10136.fir.kt
new file mode 100644
index 00000000000..b9baf44eea1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/kt10136.fir.kt
@@ -0,0 +1,8 @@
+annotation class A
+annotation class A1(val x: Int)
+
+annotation class B(
+        val a: A = A(),
+        val x: Int = A1(42).x,
+        val aa: Array<A> = arrayOf(A())
+)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/nonConstValAsArgument.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/nonConstValAsArgument.fir.kt
new file mode 100644
index 00000000000..69c4619f00e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/nonConstValAsArgument.fir.kt
@@ -0,0 +1,34 @@
+import kotlin.reflect.KClass
+
+annotation class Ann(
+        val a: Array<String> = arrayOf(readOnly),
+        val b: Array<String> = arrayOf(withGetter),
+        val c: Array<String> = arrayOf(func()),
+        val d: IntArray = intArrayOf(ONE, twoWithGetter),
+        val e: IntArray = intArrayOf(ONE + twoWithGetter),
+        val f: Array<String> = arrayOf(mutable),
+        val g: Array<String> = arrayOf(mutableWithGetter),
+        val h: Array<KClass<*>> = arrayOf(WithLateinit.kClass)
+)
+
+const val ONE = 1
+
+val twoWithGetter
+    get() = 2
+
+val readOnly = ""
+
+val withGetter
+    get() = ""
+
+fun func() = ""
+
+var mutable = ""
+
+var mutableWithGetter
+    get() = ""
+    set(x) = TODO()
+
+object WithLateinit {
+    lateinit var kClass: KClass<*>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/orderWithValue.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/orderWithValue.fir.kt
new file mode 100644
index 00000000000..464d1bced00
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/orderWithValue.fir.kt
@@ -0,0 +1,9 @@
+// FILE: A.java
+public @interface A {
+    double b();
+    Class<?> x1();
+    int a();
+    String value();
+    Class<?> x();
+    Class<?> x2();
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/orderWithoutValue.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/orderWithoutValue.fir.kt
new file mode 100644
index 00000000000..97e7759bf6c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/orderWithoutValue.fir.kt
@@ -0,0 +1,8 @@
+// FILE: A.java
+public @interface A {
+    double b();
+    Class<?> x1();
+    int a();
+    Class<?> x();
+    Class<?> x2();
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArray.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArray.fir.kt
new file mode 100644
index 00000000000..7ec64f27b78
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArray.fir.kt
@@ -0,0 +1,23 @@
+// FILE: A.java
+public @interface A {
+    String[] value();
+    Class<?> x() default Integer.class;
+    int y();
+}
+
+// FILE: b.kt
+@A("1", "2", "3", y = 1) fun test1() {}
+
+@A("4", y = 2) fun test2() {}
+
+@A(*arrayOf("5", "6"), "7", y = 3) fun test3() {}
+
+@A("1", "2", "3", x = String::class, y = 4) fun test4() {}
+
+@A("4", y = 5) fun test5() {}
+
+@A(*arrayOf("5", "6"), "7", x = Any::class, y = 6) fun test6() {}
+
+@A(y = 7) fun test7() {}
+
+@A("8", "9", "10") fun test8() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayAndOtherDefault.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayAndOtherDefault.fir.kt
new file mode 100644
index 00000000000..1be46380004
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayAndOtherDefault.fir.kt
@@ -0,0 +1,27 @@
+// FILE: A.java
+public @interface A {
+    String[] value();
+    Class<?> x() default Integer.class;
+    int y() default 1;
+}
+
+// FILE: b.kt
+@A("1", "2", "3") fun test1() {}
+
+@A("4") fun test2() {}
+
+@A(*arrayOf("5", "6"), "7") fun test3() {}
+
+@A("1", "2", "3", x = String::class) fun test4() {}
+
+@A("4", y = 2) fun test5() {}
+
+@A(*arrayOf("5", "6"), "7", x = Any::class, y = 3) fun test6() {}
+
+@A() fun test7() {}
+
+@A fun test8() {}
+
+@A(x = Any::class, *arrayOf("5", "6"), "7", y = 3) fun test9() {}
+@A(x = Any::class, value = ["5", "6"], "7", y = 3) fun test10() {}
+@A(x = Any::class, value = ["5", "6", "7"], y = 3) fun test11() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayOnly.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayOnly.fir.kt
new file mode 100644
index 00000000000..7689996da60
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayOnly.fir.kt
@@ -0,0 +1,15 @@
+// FILE: A.java
+public @interface A {
+    String[] value();
+}
+
+// FILE: b.kt
+@A("1", "2", "3") fun test1() {}
+
+@A("4") fun test2() {}
+
+@A(*arrayOf("5", "6"), "7") fun test3() {}
+
+@A() fun test4() {}
+
+@A fun test5() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayWithDefault.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayWithDefault.fir.kt
new file mode 100644
index 00000000000..7617ba14f5c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationParameters/valueArrayWithDefault.fir.kt
@@ -0,0 +1,15 @@
+// FILE: A.java
+public @interface A {
+    String[] value() default {"abc", "cde"};
+}
+
+// FILE: b.kt
+@A("1", "2", "3") fun test1() {}
+
+@A("4") fun test2() {}
+
+@A(*arrayOf("5", "6"), "7") fun test3() {}
+
+@A() fun test4() {}
+
+@A fun test5() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationWithVarargParameter/javaAnnotationWithVarargArgument.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationWithVarargParameter/javaAnnotationWithVarargArgument.fir.kt
new file mode 100644
index 00000000000..91397e85f6e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationWithVarargParameter/javaAnnotationWithVarargArgument.fir.kt
@@ -0,0 +1,11 @@
+// !WITH_NEW_INFERENCE
+
+// FILE: A.java
+public @interface A {
+    String[] value();
+}
+
+// FILE: b.kt
+@A(*arrayOf(1, "b"))
+fun test() {
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationWithVarargParameter/kotlinAnnotationWithVarargArgument.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationWithVarargParameter/kotlinAnnotationWithVarargArgument.fir.kt
new file mode 100644
index 00000000000..f0d690e8101
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationWithVarargParameter/kotlinAnnotationWithVarargArgument.fir.kt
@@ -0,0 +1,7 @@
+// !WITH_NEW_INFERENCE
+
+annotation class B(vararg val args: String)
+
+@B(*arrayOf(1, "b"))
+fun test() {
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationsTargetingLateinitAccessors.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationsTargetingLateinitAccessors.fir.kt
new file mode 100644
index 00000000000..2902dc3abda
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationsTargetingLateinitAccessors.fir.kt
@@ -0,0 +1,14 @@
+// Please make sure that this test is consistent with the blackbox test "annotationsOnLateinitAccessors.kt"
+
+import kotlin.reflect.KProperty
+
+annotation class Ann
+annotation class AnnRepeat
+
+class LateinitProperties {
+    @get:Ann
+    lateinit var y0: String
+
+    @get:Ann
+    private lateinit var y1: String
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationsTargetingNonExistentAccessor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationsTargetingNonExistentAccessor.fir.kt
new file mode 100644
index 00000000000..0500ddc0805
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/annotationsTargetingNonExistentAccessor.fir.kt
@@ -0,0 +1,114 @@
+// Please make sure that this test is consistent with the blackbox test "annotationsOnNonExistentAccessors.kt"
+
+import kotlin.reflect.KProperty
+
+annotation class Ann
+annotation class AnnRepeat
+
+class Foo(
+    @get:Ann private val y0: Int,
+    @get:Ann private vararg val y1: String
+) {
+    @get:Ann
+    private val x1 = ""
+
+    @set:Ann
+    private var x2 = ""
+
+    @setparam:Ann
+    private var x3 = ""
+
+    @setparam:[Ann AnnRepeat]
+    private var x4 = ""
+
+    @get:Ann
+    internal val x5 = ""
+
+    @get:Ann
+    protected val x6 = ""
+
+    @get:Ann
+    private val x7: String = ""
+        @AnnRepeat get
+
+    @get:Ann
+    @set:Ann
+    private var x8: String = ""
+        get() { return "" }
+
+    @get:Ann
+    @set:Ann
+    private var x9: String = ""
+        get() { return "" }
+        set(f) { field = f }
+}
+
+private class EffetivelyPrivate private constructor(
+    @get:Ann val x0: Int,
+    @get:Ann protected val x1: Int,
+    @get:Ann internal val x2: Int
+) {
+    private class Nested {
+        @get:Ann
+        val fofo = 0
+    }
+}
+
+class PrivateToThis<in I> {
+    @get:Ann
+    @set:Ann
+    @setparam:Ann
+    private var x0: I = TODO()
+}
+
+class Statics {
+    companion object {
+        @JvmField
+        @get:Ann
+        val x0 = ""
+
+        @get:Ann
+        const val x1 = ""
+
+        @JvmStatic
+        @get:Ann
+        val x2 = ""
+
+        @JvmStatic
+        @get:Ann
+        private val x3 = ""
+
+        @JvmStatic
+        @get:Ann
+        private val x4 = ""
+    }
+}
+
+private class Other(@param:Ann private val param: Int) {
+    @property:Ann
+    @field:Ann
+    private val other = ""
+
+    private fun @receiver:Ann Int.receiver() {}
+
+    @delegate:Ann
+    @get:Ann
+    private val delegate by CustomDelegate()
+}
+
+class CustomDelegate {
+    operator fun getValue(thisRef: Any?, prop: KProperty<*>): String = prop.name
+}
+
+@Retention(AnnotationRetention.SOURCE)
+annotation class SourceAnn
+
+class WithSource {
+    @get:SourceAnn
+    @set:SourceAnn
+    @setparam:SourceAnn
+    private var x0 = ""
+
+    private val x1 = ""
+        @SourceAnn get
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/defaultValueMustBeConstant.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/defaultValueMustBeConstant.fir.kt
new file mode 100644
index 00000000000..a3c86dac6b0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/defaultValueMustBeConstant.fir.kt
@@ -0,0 +1,22 @@
+import kotlin.reflect.KClass
+
+const val CONST = 1
+fun foo() = 1
+val nonConst = foo()
+
+annotation class ValidAnn(
+    val p1: Int = 1 <!AMBIGUITY!>+<!> CONST,
+    val p2: String = "",
+    val p3: KClass<*> = String::class,
+    val p4: IntArray = intArrayOf(1, 2, 3),
+    val p5: Array<String> = arrayOf("abc"),
+    val p6: Array<KClass<*>> = arrayOf(Int::class)
+)
+
+val nonConstKClass = String::class
+
+annotation class InvalidAnn(
+    val p1: Int = foo(),
+    val p2: Int = nonConst,
+    val p3: KClass<*> = nonConstKClass
+)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/explicitMetadata.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/explicitMetadata.fir.kt
new file mode 100644
index 00000000000..37c5c87499d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/explicitMetadata.fir.kt
@@ -0,0 +1,9 @@
+@Metadata
+class A
+
+@Metadata(extraString = "_")
+annotation class B(val m: Metadata)
+
+@Metadata(extraInt = 0)
+@B(Metadata())
+fun f() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/annotationAsArgument.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/annotationAsArgument.fir.kt
new file mode 100644
index 00000000000..68198f63586
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/annotationAsArgument.fir.kt
@@ -0,0 +1,19 @@
+// FILE: A.java
+public @interface A {
+    Class<?> arg() default Integer.class;
+    int x() default 1;
+    B b();
+}
+
+// FILE: B.java
+public @interface B {
+    Class<?> arg() default String.class;
+    int y() default 2;
+}
+
+// FILE: c.kt
+@A(arg = String::class, b = <!UNRESOLVED_REFERENCE!>B<!>(y = 1)) class MyClass1
+
+@A(b = <!UNRESOLVED_REFERENCE!>B<!>(y = 3)) class MyClass2
+
+@A(arg = String::class, b = <!UNRESOLVED_REFERENCE!>B<!>(arg = Boolean::class)) class MyClass3
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/arg.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/arg.fir.kt
new file mode 100644
index 00000000000..f315401b9ec
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/arg.fir.kt
@@ -0,0 +1,7 @@
+// FILE: A.java
+public @interface A {
+    Class<?> arg();
+}
+
+// FILE: b.kt
+@A(arg = String::class) class MyClass3
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argAndOtherDefault.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argAndOtherDefault.fir.kt
new file mode 100644
index 00000000000..8c63da99041
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argAndOtherDefault.fir.kt
@@ -0,0 +1,9 @@
+// FILE: A.java
+public @interface A {
+    Class<?> arg();
+    int x() default 1;
+}
+
+// FILE: b.kt
+@A(arg = String::class) class MyClass1
+@A(arg = String::class, x = 2) class MyClass2
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argArray.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argArray.fir.kt
new file mode 100644
index 00000000000..df2e3af5c26
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argArray.fir.kt
@@ -0,0 +1,7 @@
+// FILE: A.java
+public @interface A {
+    Class<?>[] arg();
+}
+
+// FILE: b.kt
+@A(arg = arrayOf(String::class, Int::class)) class MyClass
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argWithDefault.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argWithDefault.fir.kt
new file mode 100644
index 00000000000..4871b8a02be
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argWithDefault.fir.kt
@@ -0,0 +1,8 @@
+// FILE: A.java
+public @interface A {
+    Class<?> arg() default Integer.class;
+}
+
+// FILE: b.kt
+@A(arg = String::class) class MyClass1
+@A class MyClass2
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argWithDefaultAndOther.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argWithDefaultAndOther.fir.kt
new file mode 100644
index 00000000000..3afac3724b5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/argWithDefaultAndOther.fir.kt
@@ -0,0 +1,9 @@
+// FILE: A.java
+public @interface A {
+    Class<?> arg() default Integer.class;
+    int x();
+}
+
+// FILE: b.kt
+@A(arg = String::class, x = 4) class MyClass2
+@A(x = 5) class MyClass3
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/twoArgs.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/twoArgs.fir.kt
new file mode 100644
index 00000000000..aa9efe04fa6
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/twoArgs.fir.kt
@@ -0,0 +1,8 @@
+// FILE: A.java
+public @interface A {
+    Class<?> arg1();
+    Class<?> arg2();
+}
+
+// FILE: b.kt
+@A(arg1 = String::class, arg2 = Int::class) class MyClass
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/value.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/value.fir.kt
new file mode 100644
index 00000000000..ffd1adc3510
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/value.fir.kt
@@ -0,0 +1,8 @@
+// FILE: A.java
+public @interface A {
+    Class<?> value();
+}
+
+// FILE: b.kt
+@A(String::class) class MyClass1
+@A(value = String::class) class MyClass2
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueAndOtherDefault.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueAndOtherDefault.fir.kt
new file mode 100644
index 00000000000..35a0ee2d2ae
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueAndOtherDefault.fir.kt
@@ -0,0 +1,12 @@
+// FILE: A.java
+public @interface A {
+    Class<?> value();
+    int x() default 1;
+}
+
+// FILE: b.kt
+@A(String::class) class MyClass1
+@A(value = String::class) class MyClass2
+
+@A(String::class, x = 2) class MyClass3
+@A(value = String::class, x = 4) class MyClass4
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueArray.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueArray.fir.kt
new file mode 100644
index 00000000000..4fb56532c42
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueArray.fir.kt
@@ -0,0 +1,9 @@
+// FILE: A.java
+public @interface A {
+    Class<?>[] value();
+}
+
+// FILE: b.kt
+@A(String::class, Int::class) class MyClass1
+@A(*arrayOf(String::class, Int::class)) class MyClass2
+@A(value = [String::class, Int::class]) class MyClass3
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueWithDefault.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueWithDefault.fir.kt
new file mode 100644
index 00000000000..50c72be5673
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueWithDefault.fir.kt
@@ -0,0 +1,9 @@
+// FILE: A.java
+public @interface A {
+    Class<?> value() default Integer.class;
+}
+
+// FILE: b.kt
+@A(String::class) class MyClass1
+@A(value = String::class) class MyClass2
+@A class MyClass3
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueWithDefaultAndOther.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueWithDefaultAndOther.fir.kt
new file mode 100644
index 00000000000..465a8f35e3d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/javaAnnotationsWithKClassParameter/valueWithDefaultAndOther.fir.kt
@@ -0,0 +1,10 @@
+// FILE: A.java
+public @interface A {
+    Class<?> value() default Integer.class;
+    int x();
+}
+
+// FILE: b.kt
+@A(String::class, x = 2) class MyClass1
+@A(value = String::class, x = 4) class MyClass2
+@A(x = 5) class MyClass3
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/generic.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/generic.fir.kt
new file mode 100644
index 00000000000..7aff9dd45a1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/generic.fir.kt
@@ -0,0 +1,60 @@
+// !JVM_TARGET: 1.8
+// !JVM_DEFAULT_MODE: enable
+
+interface A<T> {
+    @JvmDefault
+    fun test(p: T) {
+    }
+}
+
+interface ANonDefault {
+    fun test(p: String) {}
+}
+
+interface B<T> : A<T> {
+
+    override fun test(p: T)
+    {}
+}
+
+interface C<T> : A<T>, ANonDefault {
+
+    override fun test(p: T)
+    {}
+
+    override fun test(p: String) {
+    }
+}
+
+interface C1 : C<String> {
+    override fun test(p: String) {
+
+    }
+}
+
+interface C2 : C<String>, ANonDefault {
+    override fun test(p: String) {
+
+    }
+}
+
+interface D<T> : ANonDefault, A<T> {
+
+    override fun test(p: T)
+    {}
+
+    override fun test(p: String) {
+    }
+}
+
+interface D1 : D<String> {
+    override fun test(p: String) {
+
+    }
+}
+
+interface D2 : ANonDefault, D<String> {
+    override fun test(p: String) {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/javaOverride.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/javaOverride.fir.kt
new file mode 100644
index 00000000000..c1c6958efb7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/javaOverride.fir.kt
@@ -0,0 +1,72 @@
+// !JVM_DEFAULT_MODE: enable
+// !JVM_TARGET: 1.8
+
+// FILE: JavaInterface.java
+public interface JavaInterface {
+    default void test() {}
+
+    default void testForNonDefault() {}
+
+    void testAbstract();
+}
+
+// FILE: 1.kt
+
+interface KotlinInterface : JavaInterface {
+    @JvmDefault
+    override fun test() {}
+
+    override fun testForNonDefault() {}
+
+    override fun testAbstract() {}
+}
+
+interface KotlinInterface2 : JavaInterface, KotlinInterface {
+    @JvmDefault
+    override fun test() {}
+
+    override fun testForNonDefault() {}
+
+    override fun testAbstract() {}
+}
+
+
+interface KotlinInterfaceForIndirect : JavaInterface {
+
+}
+
+interface KotlinInterfaceIndirectInheritance : KotlinInterfaceForIndirect {
+
+    @JvmDefault
+    override fun test() {}
+
+    override fun testForNonDefault() {}
+
+    override fun testAbstract() {}
+}
+
+open class KotlinClass : JavaInterface {
+    override fun test() {}
+
+    override fun testForNonDefault() {}
+
+    override fun testAbstract() {}
+}
+
+interface KotlinInterfaceX  {
+
+    fun test() {}
+
+    fun testForNonDefault() {}
+
+    fun testAbstract() {}
+}
+
+interface KotlinInterfaceManySuper: JavaInterface, KotlinInterfaceX {
+    @JvmDefault
+    override fun test() {}
+
+    override fun testForNonDefault() {}
+
+    override fun testAbstract() {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaultInInheritance.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaultInInheritance.fir.kt
new file mode 100644
index 00000000000..b9e1fa92a73
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaultInInheritance.fir.kt
@@ -0,0 +1,36 @@
+// !JVM_TARGET: 1.8
+
+interface A {
+    @JvmDefault
+    fun test() {
+    }
+}
+
+interface B : A {
+
+}
+
+
+open class Foo : B
+open class Foo2 : B, A
+
+open class FooNoError : B {
+    override fun test() {
+    }
+}
+open class Foo2NoError : B, A {
+    override fun test() {
+    }
+}
+
+class Bar : Foo()
+class Bar2 : Foo(), A
+class Bar3 : Foo(), B
+
+open class BarWithJvmDefault : B {
+    @JvmDefault
+    override fun test() {
+    }
+}
+
+class BarWithJvmDefaultSuper: BarWithJvmDefault()
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaults.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaults.fir.kt
new file mode 100644
index 00000000000..bc1be09e34d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaults.fir.kt
@@ -0,0 +1,322 @@
+// !JVM_DEFAULT_MODE: enable
+// !JVM_TARGET: 1.8
+
+public interface KInterface {
+    @JvmDefault
+    fun test(): String {
+        return "OK";
+    }
+
+    @JvmDefault
+    val property: String
+        get() = "OK"
+
+
+    fun testNonDefault(): String {
+        return "OK";
+    }
+
+    val propertyNonDefault: String
+        get() = "OK"
+}
+
+// FILE: 1.kt
+
+interface KotlinInterface : KInterface {
+    @JvmDefault
+    fun fooo() {
+        super.test()
+        super.property
+
+        super.testNonDefault()
+        super.propertyNonDefault
+
+        object  {
+            fun run () {
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>property<!>
+
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+            }
+        }
+    }
+
+    @JvmDefault
+    val propertyy: String
+        get() {
+            super.test()
+            super.property
+
+            super.testNonDefault()
+            super.propertyNonDefault
+
+            object  {
+                fun run () {
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>property<!>
+
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+                }
+            }
+            return ""
+        }
+
+    fun foooNonDefault() {
+        super.test()
+        super.property
+
+        super.testNonDefault()
+        super.propertyNonDefault
+
+        object  {
+            fun run () {
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>property<!>
+
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+            }
+        }
+    }
+
+    val propertyyNonDefault: String
+        get() {
+            super.test()
+            super.property
+
+            super.testNonDefault()
+            super.propertyNonDefault
+
+            object  {
+                fun run () {
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>property<!>
+
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+                }
+            }
+            return ""
+        }
+
+
+}
+
+interface KotlinInterfaceIndirectInheritance : KotlinInterface {
+    @JvmDefault
+    fun foooo() {
+        super.test()
+        super.property
+
+        super.testNonDefault()
+        super.propertyNonDefault
+
+        object  {
+            fun run () {
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>property<!>
+
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+            }
+        }
+    }
+
+    @JvmDefault
+    val propertyyy: String
+        get() {
+            super.test()
+            super.property
+
+            super.testNonDefault()
+            super.propertyNonDefault
+
+            object  {
+                fun run () {
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>property<!>
+
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+                }
+            }
+            return ""
+        }
+
+    fun fooooNonDefault() {
+        super.test()
+        super.property
+
+        super.testNonDefault()
+        super.propertyNonDefault
+
+        object  {
+            fun run () {
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>property<!>
+
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+            }
+        }
+    }
+
+    val propertyyyNonDefault: String
+        get() {
+            super.test()
+            super.property
+
+            super.testNonDefault()
+            super.propertyNonDefault
+
+            object  {
+                fun run () {
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>property<!>
+
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+                }
+            }
+            return ""
+        }
+}
+
+open class KotlinClass : KInterface {
+    fun foo() {
+        super.test()
+        super.property
+
+        super.testNonDefault()
+        super.propertyNonDefault
+
+        object  {
+            fun run () {
+                super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+                super@KotlinClass.<!UNRESOLVED_REFERENCE!>property<!>
+
+                super@KotlinClass.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                super@KotlinClass.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+            }
+        }
+    }
+
+    val xproperty: String
+        get() {
+            super.test()
+            super.property
+
+            super.testNonDefault()
+            super.propertyNonDefault
+
+            object  {
+                fun run () {
+                    super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+                    super@KotlinClass.<!UNRESOLVED_REFERENCE!>property<!>
+
+                    super@KotlinClass.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                    super@KotlinClass.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+                }
+            }
+
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance : KotlinClass() {
+    fun foo2() {
+        super.test()
+        super.property
+
+        super.testNonDefault()
+        super.propertyNonDefault
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>property<!>
+
+                super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+            }
+        }
+
+    }
+
+    val property2: String
+        get() {
+            super.test()
+            super.property
+
+            super.testNonDefault()
+            super.propertyNonDefault
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                    super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>property<!>
+
+                    super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                    super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+                }
+            }
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance2 : KotlinInterfaceIndirectInheritance {
+    fun foo() {
+        super.test()
+        super.property
+
+        super.testNonDefault()
+        super.propertyNonDefault
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+                super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>property<!>
+
+                super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+            }
+        }
+    }
+
+    val xproperty: String
+        get() {
+            super.test()
+            super.property
+
+            super.testNonDefault()
+            super.propertyNonDefault
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+                    super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>property<!>
+
+                    super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>testNonDefault<!>()
+                    super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>propertyNonDefault<!>
+                }
+            }
+            return ""
+        }
+}
+
+fun test() {
+    KotlinClass().test()
+    KotlinClass().property
+    KotlinClass().propertyNonDefault
+    KotlinClassIndirectInheritance2().test()
+    KotlinClassIndirectInheritance2().testNonDefault()
+    KotlinClassIndirectInheritance2().propertyyy
+    KotlinClassIndirectInheritance2().propertyyyNonDefault
+
+    KotlinClass().test()
+    KotlinClass().testNonDefault()
+    KotlinClass().property
+    KotlinClass().propertyNonDefault
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaultsWithJava.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaultsWithJava.fir.kt
new file mode 100644
index 00000000000..7c75e729663
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/jvmDefaultsWithJava.fir.kt
@@ -0,0 +1,162 @@
+// !JVM_DEFAULT_MODE: enable
+// !JVM_TARGET: 1.8
+// FILE: JavaInterface.java
+
+public interface JavaInterface {
+    default String test() {
+        return "OK";
+    }
+
+    default String testOverride() {
+        return "OK";
+    }
+}
+
+// FILE: 1.kt
+
+interface KotlinInterface : JavaInterface {
+    @JvmDefault
+    fun fooo() {
+        super.test()
+
+        object  {
+            fun run () {
+                super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    @JvmDefault
+    val propertyy: String
+        get() {
+            super.test()
+
+            object  {
+                fun run () {
+                    super@KotlinInterface.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+
+    @JvmDefault
+    override fun testOverride(): String {
+        return "OK";
+    }
+}
+
+interface KotlinInterfaceIndirectInheritance : KotlinInterface {
+    @JvmDefault
+    fun foooo() {
+        super.test()
+
+        object  {
+            fun run () {
+                super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    @JvmDefault
+    val propertyyy: String
+        get() {
+            super.test()
+
+            object  {
+                fun run () {
+                    super@KotlinInterfaceIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+open class KotlinClass : JavaInterface {
+    fun foo() {
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClass.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance : KotlinClass() {
+    fun foo2() {
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property2: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+class KotlinClassIndirectInheritance2 : KotlinInterfaceIndirectInheritance {
+    fun foo() {
+        super.test()
+        super.testOverride()
+
+        object  {
+            fun run () {
+                super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+            }
+        }
+    }
+
+    val property: String
+        get() {
+            super.test()
+            super.testOverride()
+
+            object  {
+                fun run () {
+                    super@KotlinClassIndirectInheritance2.<!UNRESOLVED_REFERENCE!>test<!>()
+                }
+            }
+            return ""
+        }
+}
+
+fun test() {
+    KotlinClass().foo()
+    KotlinClass().property
+    KotlinClassIndirectInheritance2().foo()
+    KotlinClassIndirectInheritance2().property
+
+    KotlinClass().test()
+    KotlinClass().property
+    KotlinClass().testOverride()
+    KotlinClassIndirectInheritance().testOverride()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/noJvmDefaultFlag.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/noJvmDefaultFlag.fir.kt
new file mode 100644
index 00000000000..b61ce7a12bb
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/noJvmDefaultFlag.fir.kt
@@ -0,0 +1,29 @@
+// !JVM_TARGET: 1.8
+
+interface B {
+
+    @JvmDefault
+    fun test() {}
+
+    @JvmDefault
+    abstract fun test2(s: String = "")
+
+    @JvmDefault
+    abstract fun test3()
+
+
+    @JvmDefault
+    abstract val prop: String
+
+    @JvmDefault
+    abstract val prop2: String
+
+    @JvmDefault
+    val prop3: String
+        get() = ""
+
+    @JvmDefault
+    var prop4: String
+        get() = ""
+        set(value) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/notInterface.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/notInterface.fir.kt
new file mode 100644
index 00000000000..73c1c6de9ae
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/notInterface.fir.kt
@@ -0,0 +1,22 @@
+// !JVM_TARGET: 1.8
+
+abstract class A {
+
+    @JvmDefault
+    fun test() {}
+
+    @JvmDefault
+    abstract fun test2(s: String = "")
+
+    @JvmDefault
+    abstract fun test3()
+}
+
+object B {
+
+    @JvmDefault
+    fun test() {}
+
+    @JvmDefault
+    fun test2(s: String = "") {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/propertyAccessor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/propertyAccessor.fir.kt
new file mode 100644
index 00000000000..7ac115521e6
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/propertyAccessor.fir.kt
@@ -0,0 +1,14 @@
+// !JVM_TARGET: 1.8
+// !JVM_DEFAULT_MODE: enable
+
+interface B {
+
+    @JvmDefault
+    val prop1: String
+    @JvmDefault get() = ""
+
+
+    var prop2: String
+        @JvmDefault get() = ""
+        @JvmDefault set(value) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/simpleOverride.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/simpleOverride.fir.kt
new file mode 100644
index 00000000000..9e1c054796d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/simpleOverride.fir.kt
@@ -0,0 +1,31 @@
+// !JVM_TARGET: 1.8
+// !JVM_DEFAULT_MODE: enable
+
+interface A {
+    @JvmDefault
+    fun test() {}
+}
+
+interface Abstract : A {
+    override fun test()
+}
+
+interface ANonDefault {
+    fun test() {}
+}
+
+interface B: A {
+    override fun test() {}
+}
+
+interface C: ANonDefault, A {
+    override fun test() {}
+}
+
+interface D: A, ANonDefault {
+    override fun test() {}
+}
+
+class Foo : A {
+    override fun test() {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/simplePropertyOverride.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/simplePropertyOverride.fir.kt
new file mode 100644
index 00000000000..f5b65653e85
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/simplePropertyOverride.fir.kt
@@ -0,0 +1,32 @@
+// !JVM_TARGET: 1.8
+// !JVM_DEFAULT_MODE: enable
+
+interface A {
+    @JvmDefault
+    val test: String
+        get() = "OK"
+}
+
+interface Abstract : A {
+    override val test: String
+}
+
+interface ANonDefault {
+    val test: String
+        get() = "ANonDefault"
+}
+
+interface B: A {
+    override val test: String
+        get() = "B"
+}
+
+interface C: ANonDefault, A {
+    override val test: String
+        get() = "C"
+}
+
+interface D: A, ANonDefault {
+    override val test: String
+        get() = "C"
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCall.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCall.fir.kt
new file mode 100644
index 00000000000..55ae915c290
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCall.fir.kt
@@ -0,0 +1,62 @@
+// !JVM_TARGET: 1.8
+// FILE: 1.kt
+interface A {
+    @JvmDefault
+    fun test() {
+    }
+}
+
+// FILE: 2.kt
+interface B : A {
+
+}
+
+interface C : B {
+    @JvmDefault
+    override fun test() {
+        super.test()
+    }
+}
+
+open class Foo : B {
+    override fun test() {
+        super.test()
+    }
+}
+open class Foo2 : B
+
+open class Bar : Foo2() {
+    override fun test() {
+        super.test()
+    }
+}
+
+open class Bar2 : Bar() {
+    override fun test() {
+        super.test()
+    }
+}
+
+class ManySupers: Foo2(), B {
+    fun foo() {
+        super<Foo2>.test()
+        super<B>.test()
+        super.test()
+    }
+}
+
+class ManySupers2: Foo2(), C {
+    fun foo() {
+        super<Foo2>.test()
+        super<C>.test()
+        super.test()
+    }
+}
+
+class ManySupers3: Bar2(), C {
+    fun foo() {
+        super<Bar2>.test()
+        super<C>.test()
+        super.test()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity.fir.kt
new file mode 100644
index 00000000000..675f9586dc7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity.fir.kt
@@ -0,0 +1,32 @@
+// !JVM_TARGET: 1.8
+interface A {
+    @JvmDefault
+    fun test() {
+    }
+}
+
+interface B{
+    fun test() {
+    }
+}
+
+interface AB: A, B
+
+interface BA: B, A
+
+
+interface C : A, B {
+    @JvmDefault
+    override fun test() {
+        super<B>.test()
+        super<A>.test()
+    }
+}
+
+interface D : B, A {
+    @JvmDefault
+    override fun test() {
+        super<B>.test()
+        super<A>.test()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity2.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity2.fir.kt
new file mode 100644
index 00000000000..cd2701cd0c0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity2.fir.kt
@@ -0,0 +1,32 @@
+// !JVM_TARGET: 1.8
+interface A {
+    @JvmDefault
+    fun test()
+}
+
+interface B{
+    fun test() {
+    }
+}
+
+interface AB: A, B
+
+interface BA: B, A
+
+class C : A, B {
+    override fun test() {
+        super<B>.test()
+    }
+}
+
+class D : B, A {
+    override fun test() {
+        super<B>.test()
+    }
+}
+
+class E: B, A {
+    fun foo() {
+        super<B>.test()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity3.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity3.fir.kt
new file mode 100644
index 00000000000..8df79b04f13
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/superCallAmbiguity3.fir.kt
@@ -0,0 +1,31 @@
+// !JVM_TARGET: 1.8
+interface A {
+    @JvmDefault
+    fun test() {
+
+    }
+}
+
+interface B{
+    fun test()
+}
+interface AB : A, B
+interface BA : B, A
+
+class C : A, B {
+    override fun test() {
+        super<A>.test()
+    }
+}
+
+class D : B, A {
+    override fun test() {
+        super<A>.test()
+    }
+}
+
+class E: B, A {
+    fun foo() {
+        super<A>.test()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/target6.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/target6.fir.kt
new file mode 100644
index 00000000000..6c733fee156
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/target6.fir.kt
@@ -0,0 +1,29 @@
+// !JVM_TARGET: 1.6
+
+interface B {
+
+    @JvmDefault
+    fun test() {}
+
+    @JvmDefault
+    abstract fun test2(s: String = "")
+
+    @JvmDefault
+    abstract fun test3()
+
+
+    @JvmDefault
+    abstract val prop: String
+
+    @JvmDefault
+    abstract val prop2: String
+
+    @JvmDefault
+    val prop3: String
+        get() = ""
+
+    @JvmDefault
+    var prop4: String
+        get() = ""
+        set(value) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/target8.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/target8.fir.kt
new file mode 100644
index 00000000000..35b71d2bba0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmDefault/target8.fir.kt
@@ -0,0 +1,30 @@
+// !JVM_TARGET: 1.8
+// !JVM_DEFAULT_MODE: enable
+
+interface B {
+
+    @JvmDefault
+    fun test() {}
+
+    @JvmDefault
+    abstract fun test2(s: String = "")
+
+    @JvmDefault
+    abstract fun test3()
+
+
+    @JvmDefault
+    abstract val prop: String
+
+    @JvmDefault
+    abstract val prop2: String
+
+    @JvmDefault
+    val prop3: String
+        get() = ""
+
+    @JvmDefault
+    var prop4: String
+        get() = ""
+        set(value) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/clashWithCompanionObjectField.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/clashWithCompanionObjectField.fir.kt
new file mode 100644
index 00000000000..6d48f4be934
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/clashWithCompanionObjectField.fir.kt
@@ -0,0 +1,8 @@
+class A {
+
+    @JvmField val clash = 1;
+
+    companion object {
+        val clash = 1;
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/inMultiFileFacade.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/inMultiFileFacade.fir.kt
new file mode 100644
index 00000000000..968c887cb2a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/inMultiFileFacade.fir.kt
@@ -0,0 +1,13 @@
+@file:kotlin.jvm.JvmMultifileClass
+@file:JvmName("SomeName")
+
+@JvmField
+val c = 4
+
+@JvmField
+var g = 5
+
+class C {
+    @JvmField
+    var g = 5
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/inSingleFileFacade.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/inSingleFileFacade.fir.kt
new file mode 100644
index 00000000000..5422d3c7004
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/inSingleFileFacade.fir.kt
@@ -0,0 +1,12 @@
+@file:JvmName("SomeName")
+
+@JvmField
+val c = 4
+
+@JvmField
+var g = 5
+
+class C {
+    @JvmField
+    var g = 5
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/interface13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/interface13.fir.kt
new file mode 100644
index 00000000000..79b17440a69
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/interface13.fir.kt
@@ -0,0 +1,59 @@
+// !LANGUAGE: +JvmFieldInInterface
+
+interface A {
+
+    companion object {
+        @JvmField
+        val c = 3
+    }
+}
+
+
+interface B {
+
+    companion object {
+        @JvmField
+        val c = 3
+
+        @JvmField
+        val a = 3
+    }
+}
+
+interface C {
+    companion object {
+        @JvmField
+        val c = 3
+
+        val a = 3
+    }
+}
+
+interface D {
+    companion object {
+        @JvmField
+        var c = 3
+    }
+}
+
+
+interface E {
+    companion object {
+        @JvmField
+        private val a = 3
+
+        @JvmField
+        internal val b = 3
+
+        @JvmField
+        protected val c = 3
+    }
+}
+
+
+interface F {
+    companion object {
+        @JvmField
+        open val a = 3
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/jvmFieldApplicability.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/jvmFieldApplicability.fir.kt
new file mode 100644
index 00000000000..81ad67b7c2f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmField/jvmFieldApplicability.fir.kt
@@ -0,0 +1,143 @@
+// !LANGUAGE: +NestedClassesInAnnotations +InlineClasses
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+@kotlin.jvm.JvmField
+fun foo() {
+    @kotlin.jvm.JvmField val x = "A"
+}
+
+annotation class DemoAnnotation
+
+@JvmField
+abstract class C : I{
+
+    @kotlin.jvm.JvmField constructor(s: String) {
+    }
+
+    @kotlin.jvm.JvmField private fun foo(s: String = "OK") {
+    }
+
+    @JvmField val a: String by lazy { "A" }
+
+    @JvmField open val b: Int = 3
+
+    @JvmField abstract val c: Int
+
+    @JvmField
+    val customGetter: String = ""
+        get() = field
+
+    @JvmField
+    val explicitDefaultGetter: String = ""
+        get
+
+    @JvmField
+    var explicitDefaultSetter: String = ""
+        set
+
+    @JvmField
+    val explicitDefaultAnnotatedGetter: String = ""
+        @DemoAnnotation get
+
+    @JvmField
+    var explicitDefaultAnnotatedSetter: String = ""
+        @DemoAnnotation set
+
+    @JvmField
+    var customSetter: String = ""
+        set(s) {
+            field = s
+        }
+
+    @JvmField
+    val noBackingField: String
+        get() = "a"
+
+    @JvmField
+    final override val ai = 3
+
+    @JvmField
+    private val private = 3
+}
+
+interface I {
+    @JvmField val ai: Int
+    @JvmField val bi: Int
+        get() = 5
+}
+
+class G {
+    @JvmField
+    lateinit var lateInit: String
+
+    @delegate:JvmField
+    val s: String by lazy { "s" }
+}
+
+@JvmField
+const val Const = 4
+
+@JvmField
+var i = 5
+
+class H {
+    companion object {
+        @JvmField
+        var c = 3
+    }
+}
+
+interface K {
+
+    val i: Int
+    val j: Int
+
+    companion object {
+        @JvmField
+        var c = 3
+
+        var x = 3
+    }
+}
+
+class KK : K {
+    @JvmField
+    override val i: Int = 0
+    @JvmField
+    override final val j: Int = 0
+}
+
+open class KKK : K {
+    @JvmField
+    override val i: Int = 0
+    @JvmField
+    override final val j: Int = 0
+}
+
+annotation class L {
+    companion object {
+        @JvmField
+        var c = 3
+    }
+}
+
+object O {
+    @JvmField
+    val c = 3
+}
+
+@JvmField
+private val private = 3
+
+inline class Foo(val x: Int)
+
+object IObject {
+    @JvmField
+    val c: Foo = Foo(42)
+
+    @JvmField
+    val u = 42u
+
+    @JvmField
+    private val r: Result<Int> = TODO()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/JvmOverloadWithNoDefaults.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/JvmOverloadWithNoDefaults.fir.kt
new file mode 100644
index 00000000000..5ddbe4cea11
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/JvmOverloadWithNoDefaults.fir.kt
@@ -0,0 +1,7 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class C {
+    @kotlin.jvm.JvmOverloads constructor() {
+    }
+
+    @kotlin.jvm.JvmOverloads fun foo(s: String) {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAbstractMethods.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAbstractMethods.fir.kt
new file mode 100644
index 00000000000..ab222d7bc41
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAbstractMethods.fir.kt
@@ -0,0 +1,11 @@
+interface T {
+    @kotlin.jvm.JvmOverloads fun foo(s: String = "OK")
+
+    @kotlin.jvm.JvmOverloads fun bar(s: String = "OK") {
+    }
+}
+
+
+abstract class C {
+    @kotlin.jvm.JvmOverloads abstract fun foo(s: String = "OK")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAnnotationClassConstructor_1_3.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAnnotationClassConstructor_1_3.fir.kt
new file mode 100644
index 00000000000..f28b42adf09
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAnnotationClassConstructor_1_3.fir.kt
@@ -0,0 +1,4 @@
+// !LANGUAGE: -ProhibitJvmOverloadsOnConstructorsOfAnnotationClasses
+
+annotation class A1 @JvmOverloads constructor(val x: Int = 1)
+annotation class A2 @JvmOverloads constructor()
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAnnotationClassConstructor_1_4.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAnnotationClassConstructor_1_4.fir.kt
new file mode 100644
index 00000000000..576ebfa6b2f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnAnnotationClassConstructor_1_4.fir.kt
@@ -0,0 +1,4 @@
+// !LANGUAGE: +ProhibitJvmOverloadsOnConstructorsOfAnnotationClasses
+
+annotation class A1 @JvmOverloads constructor(val x: Int = 1)
+annotation class A2 @JvmOverloads constructor()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnPrivate.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnPrivate.fir.kt
new file mode 100644
index 00000000000..95fc927051a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmOverloads/jvmOverloadsOnPrivate.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class C {
+    @kotlin.jvm.JvmOverloads private fun foo(s: String = "OK") {
+    }
+
+    @kotlin.jvm.JvmOverloads fun bar(s: String = "OK") {
+    }
+}
+
+fun foo() {
+    @kotlin.jvm.JvmOverloads fun quux(s: String = "OK") {
+    }
+
+    class D {
+        @kotlin.jvm.JvmOverloads fun foo(s: String = "OK") {
+        }
+    }
+
+    val x = object {
+        @kotlin.jvm.JvmOverloads fun foo(s: String = "OK") {
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmPackageName/incorrectJvmPackageName.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmPackageName/incorrectJvmPackageName.fir.kt
new file mode 100644
index 00000000000..12ce9ee1123
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmPackageName/incorrectJvmPackageName.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -INVISIBLE_MEMBER -INVISIBLE_REFERENCE
+
+// FILE: b.kt
+@file:JvmPackageName("")
+package b
+fun b() {}
+
+// FILE: c.kt
+@file:JvmPackageName("invalid-fq-name")
+package c
+fun c() {}
+
+// FILE: d.kt
+@file:JvmPackageName("d")
+package d
+class D
+fun d() {}
+
+// FILE: e.kt
+@file:JvmPackageName(42)
+package e
+fun e() {}
+
+// FILE: f.kt
+@file:JvmPackageName(f)
+package f
+const val name = "f"
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmSpecialFunctions/apiVersionIsAtLeastHasConstArguments.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmSpecialFunctions/apiVersionIsAtLeastHasConstArguments.fir.kt
new file mode 100644
index 00000000000..29c9bf90911
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmSpecialFunctions/apiVersionIsAtLeastHasConstArguments.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// SKIP_TXT
+// FILE: test.kt
+package test
+
+import kotlin.internal.*
+
+const val ZERO = 0
+const val ONE = 1
+
+fun zero() = 0
+val one = 1
+
+val test0 = apiVersionIsAtLeast(0, 0, 0)
+val testConstVals = apiVersionIsAtLeast(ONE, ONE, ZERO)
+val testConstExprs = apiVersionIsAtLeast(ONE + 0, 1 + 0, ((0 + 1 + 0)))
+val testNonConstExprs = apiVersionIsAtLeast(one, zero(), one + 1)
+
+// FILE: apiVersionIsAtLeast.kt
+package kotlin.internal
+
+fun apiVersionIsAtLeast(epic: Int, major: Int, minor: Int): Boolean =
+        false
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constOrJvmFieldProperty.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constOrJvmFieldProperty.fir.kt
new file mode 100644
index 00000000000..3a29c08a590
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constOrJvmFieldProperty.fir.kt
@@ -0,0 +1,18 @@
+class A {
+
+    companion object {
+
+        @JvmStatic const val z = 1;
+
+        @JvmStatic @JvmField val x = 1;
+    }
+
+}
+
+
+object B {
+
+    @JvmStatic const val z = 1;
+
+    @JvmStatic @JvmField val x = 1;
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructorProperty.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructorProperty.fir.kt
new file mode 100644
index 00000000000..38faac870eb
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructorProperty.fir.kt
@@ -0,0 +1,4 @@
+// !LANGUAGE: -JvmStaticInInterface
+class A(@JvmStatic val z: Int) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructorProperty_LL13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructorProperty_LL13.fir.kt
new file mode 100644
index 00000000000..5de49892b9a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructorProperty_LL13.fir.kt
@@ -0,0 +1,4 @@
+// !LANGUAGE: +JvmStaticInInterface
+class A(@JvmStatic val z: Int) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructors.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructors.fir.kt
new file mode 100644
index 00000000000..1a3bde84266
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/constructors.fir.kt
@@ -0,0 +1,8 @@
+class A {
+    @JvmStatic constructor() {}
+    inner class B {
+        @JvmStatic constructor() {}
+    }
+}
+
+class C @JvmStatic constructor()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/finalAndAbstract.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/finalAndAbstract.fir.kt
new file mode 100644
index 00000000000..a37ff0e192d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/finalAndAbstract.fir.kt
@@ -0,0 +1,33 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+abstract class A {
+
+    open fun a() {}
+
+    abstract fun b()
+
+    open fun c() {}
+}
+
+object B: A() {
+
+    @JvmStatic override fun a() {}
+
+    @JvmStatic override fun b() {}
+
+    @JvmStatic final override fun c() {}
+
+    @JvmStatic open fun d() {}
+}
+
+class C {
+
+    companion object: A() {
+        @JvmStatic override fun a() {}
+
+        @JvmStatic override fun b() {}
+
+        @JvmStatic final override fun c() {}
+
+        @JvmStatic open fun d() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/functions.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/functions.fir.kt
new file mode 100644
index 00000000000..d638e96691d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/functions.fir.kt
@@ -0,0 +1,53 @@
+// !LANGUAGE: -JvmStaticInInterface
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+class A {
+    companion object {
+        @JvmStatic fun a1() {
+
+        }
+    }
+
+    object A {
+        @JvmStatic fun a2() {
+
+        }
+    }
+
+    fun test() {
+        val s = object {
+            @JvmStatic fun a3() {
+
+            }
+        }
+    }
+
+    @JvmStatic fun a4() {
+
+    }
+}
+
+interface B {
+    companion object {
+        @JvmStatic fun a1() {
+
+        }
+    }
+
+    object A {
+        @JvmStatic fun a2() {
+
+        }
+    }
+
+    fun test() {
+        val s = object {
+            @JvmStatic fun a3() {
+
+            }
+        }
+    }
+
+    @JvmStatic fun a4() {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/functions_LL13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/functions_LL13.fir.kt
new file mode 100644
index 00000000000..9ae6708cd09
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/functions_LL13.fir.kt
@@ -0,0 +1,53 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !LANGUAGE: +JvmStaticInInterface
+class A {
+    companion object {
+        @JvmStatic fun a1() {
+
+        }
+    }
+
+    object A {
+        @JvmStatic fun a2() {
+
+        }
+    }
+
+    fun test() {
+        val s = object {
+            @JvmStatic fun a3() {
+
+            }
+        }
+    }
+
+    @JvmStatic fun a4() {
+
+    }
+}
+
+interface B {
+    companion object {
+        @JvmStatic fun a1() {
+
+        }
+    }
+
+    object A {
+        @JvmStatic fun a2() {
+
+        }
+    }
+
+    fun test() {
+        val s = object {
+            @JvmStatic fun a3() {
+
+            }
+        }
+    }
+
+    @JvmStatic fun a4() {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL12.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL12.fir.kt
new file mode 100644
index 00000000000..7f69d354701
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL12.fir.kt
@@ -0,0 +1,54 @@
+// !LANGUAGE: -JvmStaticInInterface
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+interface B {
+    companion object {
+        @JvmStatic fun a1() {
+
+        }
+
+        @JvmStatic private fun a2() {
+
+        }
+
+        @JvmStatic protected fun a3() {
+
+        }
+
+        @JvmStatic internal fun a4() {
+
+        }
+
+        @JvmStatic
+        var foo = 1
+
+        @JvmStatic
+        var foo1 = 1
+            protected set
+
+        @JvmStatic
+        var foo2 = 1
+            private set
+
+        @JvmStatic
+        private var foo3 = 1
+
+        @JvmStatic
+        protected var foo4 = 1
+
+        @JvmStatic
+        protected var foo5 = 1
+
+        @JvmStatic
+        val foo6 = 1
+
+        val foo7 = 1
+            @JvmStatic get
+
+        private var foo8 = 1
+        @JvmStatic public set
+
+        public var foo9 = 1
+        @JvmStatic private set
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL13_16.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL13_16.fir.kt
new file mode 100644
index 00000000000..073edc66c0f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL13_16.fir.kt
@@ -0,0 +1,55 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !LANGUAGE: +JvmStaticInInterface
+interface B {
+    companion object {
+        @JvmStatic fun a1() {
+
+        }
+
+        @JvmStatic private fun a2() {
+
+        }
+
+        @JvmStatic protected fun a3() {
+
+        }
+
+        @JvmStatic internal fun a4() {
+
+        }
+
+        @JvmStatic
+        var foo = 1
+
+        @JvmStatic
+        var foo1 = 1
+            protected set
+
+        @JvmStatic
+        var foo2 = 1
+            private set
+
+        @JvmStatic
+        private var foo3 = 1
+
+        @JvmStatic
+        protected var foo4 = 1
+
+        @JvmStatic
+        protected var foo5 = 1
+
+        @JvmStatic
+        val foo6 = 1
+
+        val foo7 = 1
+        @JvmStatic get
+
+        private var foo8 = 1
+        @JvmStatic public set
+
+        public var foo9 = 1
+        @JvmStatic private set
+
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL13_18.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL13_18.fir.kt
new file mode 100644
index 00000000000..aafae7e4f93
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/interfaceCompanion_LL13_18.fir.kt
@@ -0,0 +1,56 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !LANGUAGE: +JvmStaticInInterface
+// !JVM_TARGET: 1.8
+interface B {
+    companion object {
+        @JvmStatic fun a1() {
+
+        }
+
+        @JvmStatic private fun a2() {
+
+        }
+
+        @JvmStatic protected fun a3() {
+
+        }
+
+        @JvmStatic internal fun a4() {
+
+        }
+
+        @JvmStatic
+        var foo = 1
+
+        @JvmStatic
+        var foo1 = 1
+            protected set
+
+        @JvmStatic
+        var foo2 = 1
+            private set
+
+        @JvmStatic
+        private var foo3 = 1
+
+        @JvmStatic
+        protected var foo4 = 1
+
+        @JvmStatic
+        protected var foo5 = 1
+
+        @JvmStatic
+        val foo6 = 1
+
+        val foo7 = 1
+        @JvmStatic get
+
+        private var foo8 = 1
+        @JvmStatic public set
+
+        public var foo9 = 1
+        @JvmStatic private set
+
+    }
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/localFun.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/localFun.fir.kt
new file mode 100644
index 00000000000..b80f0bdead0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/localFun.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: -JvmStaticInInterface
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+fun main() {
+    @JvmStatic fun a(){
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/localFun_LL13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/localFun_LL13.fir.kt
new file mode 100644
index 00000000000..0892836749c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/localFun_LL13.fir.kt
@@ -0,0 +1,7 @@
+// !LANGUAGE: +JvmStaticInInterface
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+fun main() {
+    @JvmStatic fun a(){
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/property.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/property.fir.kt
new file mode 100644
index 00000000000..5913ec6959e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/property.fir.kt
@@ -0,0 +1,45 @@
+// !LANGUAGE: -JvmStaticInInterface
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+open class B {
+    public open val base1 : Int = 1
+    public open val base2 : Int = 1
+}
+
+class A {
+    companion object : B() {
+        var p1:Int = 1
+            @JvmStatic set(p: Int) {
+                p1 = 1
+            }
+
+        @JvmStatic val z = 1;
+
+        @JvmStatic override val base1: Int = 0
+
+        override val base2: Int = 0
+            @JvmStatic get
+    }
+
+    object A : B() {
+        var p:Int = 1
+            @JvmStatic set(p1: Int) {
+                p = 1
+            }
+
+        @JvmStatic val z = 1;
+
+        @JvmStatic override val base1: Int = 0
+
+        @JvmStatic open fun f() {}
+
+        override val base2: Int = 0
+            @JvmStatic get
+    }
+
+    var p:Int = 1
+        @JvmStatic set(p1: Int) {
+            p = 1
+        }
+
+    @JvmStatic val z2 = 1;
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/property_LL13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/property_LL13.fir.kt
new file mode 100644
index 00000000000..3d44a883fa3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/jvmStatic/property_LL13.fir.kt
@@ -0,0 +1,45 @@
+// !LANGUAGE: +JvmStaticInInterface
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+open class B {
+    public open val base1 : Int = 1
+    public open val base2 : Int = 1
+}
+
+class A {
+    companion object : B() {
+        var p1:Int = 1
+            @JvmStatic set(p: Int) {
+                p1 = 1
+            }
+
+        @JvmStatic val z = 1;
+
+        @JvmStatic override val base1: Int = 0
+
+        override val base2: Int = 0
+            @JvmStatic get
+    }
+
+    object A : B() {
+        var p:Int = 1
+            @JvmStatic set(p1: Int) {
+                p = 1
+            }
+
+        @JvmStatic val z = 1;
+
+        @JvmStatic override val base1: Int = 0
+
+        @JvmStatic open fun f() {}
+
+        override val base2: Int = 0
+            @JvmStatic get
+    }
+
+    var p:Int = 1
+        @JvmStatic set(p1: Int) {
+            p = 1
+        }
+
+    @JvmStatic val z2 = 1;
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassArrayInAnnotationsInVariance.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassArrayInAnnotationsInVariance.fir.kt
new file mode 100644
index 00000000000..c9bcbb129f4
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassArrayInAnnotationsInVariance.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+
+import kotlin.reflect.KClass
+
+open class A
+class B1 : A()
+class B2 : A()
+
+annotation class Ann1(val arg: Array<KClass<in A>>)
+
+@Ann1(arrayOf(A::class))
+class MyClass1
+
+@Ann1(arrayOf(Any::class))
+class MyClass1a
+
+@Ann1(arrayOf(B1::class))
+class MyClass2
+
+annotation class Ann2(val arg: Array<KClass<in B1>>)
+
+@Ann2(arrayOf(A::class))
+class MyClass3
+
+@Ann2(arrayOf(B1::class))
+class MyClass4
+
+@Ann2(arrayOf(B2::class))
+class MyClass5
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassArrayInAnnotationsOutVariance.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassArrayInAnnotationsOutVariance.fir.kt
new file mode 100644
index 00000000000..4c8f7fa4288
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassArrayInAnnotationsOutVariance.fir.kt
@@ -0,0 +1,29 @@
+// !WITH_NEW_INFERENCE
+
+import kotlin.reflect.KClass
+
+open class A
+class B1 : A()
+class B2 : A()
+
+annotation class Ann1(val arg: Array<KClass<out A>>)
+
+@Ann1(arrayOf(A::class))
+class MyClass1
+
+@Ann1(arrayOf(Any::class))
+class MyClass1a
+
+@Ann1(arrayOf(B1::class))
+class MyClass2
+
+annotation class Ann2(val arg: Array<KClass<out B1>>)
+
+@Ann2(arrayOf(A::class))
+class MyClass3
+
+@Ann2(arrayOf(B1::class))
+class MyClass4
+
+@Ann2(arrayOf(B2::class))
+class MyClass5
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotation.fir.kt
new file mode 100644
index 00000000000..640ea5cfb18
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotation.fir.kt
@@ -0,0 +1,20 @@
+import kotlin.reflect.KClass
+
+annotation class Ann1(val arg: KClass<*>)
+annotation class Ann2(vararg val arg: KClass<*>)
+annotation class Ann3(val arg: Array<KClass<*>>)
+
+class A1
+class A2
+
+@Ann1(A1::class)
+@Ann2(A1::class, A2::class)
+@Ann3(arrayOf(A1::class, A2::class))
+class MyClass1
+
+@Ann1(<!UNRESOLVED_REFERENCE!>A3<!>::class)
+class MyClass2
+
+val x = A1::class
+@Ann1(x)
+class MyClass3
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotationsInVariance.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotationsInVariance.fir.kt
new file mode 100644
index 00000000000..0a6c837b9db
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotationsInVariance.fir.kt
@@ -0,0 +1,27 @@
+import kotlin.reflect.KClass
+
+open class A
+class B1 : A()
+class B2 : A()
+
+annotation class Ann1(val arg: KClass<in A>)
+
+@Ann1(A::class)
+class MyClass1
+
+@Ann1(Any::class)
+class MyClass1a
+
+@Ann1(B1::class)
+class MyClass2
+
+annotation class Ann2(val arg: KClass<in B1>)
+
+@Ann2(A::class)
+class MyClass3
+
+@Ann2(B1::class)
+class MyClass4
+
+@Ann2(B2::class)
+class MyClass5
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotationsOutVariance.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotationsOutVariance.fir.kt
new file mode 100644
index 00000000000..c8f3653fa84
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInAnnotationsOutVariance.fir.kt
@@ -0,0 +1,27 @@
+import kotlin.reflect.KClass
+
+open class A
+class B1 : A()
+class B2 : A()
+
+annotation class Ann1(val arg: KClass<out A>)
+
+@Ann1(A::class)
+class MyClass1
+
+@Ann1(Any::class)
+class MyClass1a
+
+@Ann1(B1::class)
+class MyClass2
+
+annotation class Ann2(val arg: KClass<out B1>)
+
+@Ann2(A::class)
+class MyClass3
+
+@Ann2(B1::class)
+class MyClass4
+
+@Ann2(B2::class)
+class MyClass5
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInvariantTP.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInvariantTP.fir.kt
new file mode 100644
index 00000000000..d29699497ad
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassInvariantTP.fir.kt
@@ -0,0 +1,23 @@
+import kotlin.reflect.KClass
+
+open class A
+class B : A()
+
+annotation class Ann1(val arg: KClass<A>)
+
+@Ann1(A::class)
+class MyClass1
+
+@Ann1(Any::class)
+class MyClass1a
+
+@Ann1(B::class)
+class MyClass2
+
+annotation class Ann2(val arg: KClass<B>)
+
+@Ann2(A::class)
+class MyClass3
+
+@Ann2(B::class)
+class MyClass4
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassOutArrayInAnnotationsOutVariance.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassOutArrayInAnnotationsOutVariance.fir.kt
new file mode 100644
index 00000000000..948fc6161b0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/kClass/kClassOutArrayInAnnotationsOutVariance.fir.kt
@@ -0,0 +1,7 @@
+import kotlin.reflect.KClass
+
+open class A
+class B1 : A()
+class B2 : A()
+
+annotation class Ann1(val arg: Array<out KClass<out A>>)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/kotlinAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/kotlinAnnotation.fir.kt
new file mode 100644
index 00000000000..be23e84ff89
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/kotlinAnnotation.fir.kt
@@ -0,0 +1,5 @@
+annotation class Ann(val x: Int, val value: String, val y: Double)
+
+@Ann(value = "a", x = 1, y = 1.0) fun foo1() {}
+@Ann(2, "b", 2.0) fun foo2() {}
+@Ann(3, "c", y = 2.0) fun foo3() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/tooManyArgs.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/tooManyArgs.fir.kt
new file mode 100644
index 00000000000..170d4221995
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/tooManyArgs.fir.kt
@@ -0,0 +1,11 @@
+// FILE: A.java
+public @interface A {
+    int a();
+    double b();
+    boolean x();
+}
+
+// FILE: b.kt
+@A(false,
+1.0,
+false, 1, 2) fun foo1() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/typeMismatch.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/typeMismatch.fir.kt
new file mode 100644
index 00000000000..3b5db4e2084
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/typeMismatch.fir.kt
@@ -0,0 +1,13 @@
+// FILE: A.java
+public @interface A {
+    int a();
+    double b();
+    boolean x();
+}
+
+// FILE: b.kt
+@A(false,
+1.0,
+false) fun foo1() {}
+
+@A(2.0, x = true, b = 2.0) fun foo2() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/withValue.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/withValue.fir.kt
new file mode 100644
index 00000000000..d2766ff2519
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/withValue.fir.kt
@@ -0,0 +1,17 @@
+// FILE: A.java
+public @interface A {
+    int a();
+    double b();
+    String value();
+    boolean x();
+}
+
+// FILE: b.kt
+@A("v1", 1,
+1.0,
+false) fun foo1() {}
+
+@A("v2", 2, x = true, b = 2.0) fun foo2() {}
+
+@A("v2", x = true, b = 3.0, a = 4) fun foo3() {}
+@A(value = "v2", x = true, b = 3.0, a = 4) fun foo4() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/withoutValue.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/withoutValue.fir.kt
new file mode 100644
index 00000000000..b0c8cf02472
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/prohibitPositionedArgument/withoutValue.fir.kt
@@ -0,0 +1,17 @@
+// FILE: A.java
+public @interface A {
+    int a();
+    double b();
+    boolean x();
+}
+
+// FILE: b.kt
+@A(1,
+1.0,
+false) fun foo1() {}
+
+@A(2, x = true, b = 2.0) fun foo2() {}
+
+@A(x = true, b = 3.0, a = 4) fun foo3() {}
+
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/qualifiedCallValue.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/qualifiedCallValue.fir.kt
new file mode 100644
index 00000000000..3ec4a43aa00
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/qualifiedCallValue.fir.kt
@@ -0,0 +1,27 @@
+// !DIAGNOSTICS: -JAVA_LANG_CLASS_PARAMETER_IN_ANNOTATION
+package a.b.c
+
+@kotlin.Deprecated("aaa")
+@ann1(kotlin.Deprecated("aaa"))
+
+@a.b.c.ann1()
+@ann2(a.b.c.ann1())
+
+@A.IAnn()
+@ann3(A.IAnn())
+
+@a.b.c.A.IAnn()
+@ann3(a.b.c.A.IAnn())
+
+@annArray(kotlin.arrayOf("a"))
+fun test() = 1
+
+annotation class ann1(val p: Deprecated = kotlin.Deprecated("aaa"))
+annotation class ann2(val p: ann1 = a.b.c.ann1())
+annotation class ann3(val p: A.IAnn = A.IAnn(), val p2: A.IAnn = a.b.c.A.IAnn())
+
+annotation class annArray(val p: Array<String> = kotlin.arrayOf("a"))
+
+class A {
+    annotation class IAnn
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/strictfpOnClass.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/strictfpOnClass.fir.kt
new file mode 100644
index 00000000000..8d3aa87090d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/strictfpOnClass.fir.kt
@@ -0,0 +1,17 @@
+@kotlin.jvm.Strictfp class A {
+
+}
+
+@kotlin.jvm.Strictfp object B {
+
+}
+
+@kotlin.jvm.Strictfp interface C {
+
+}
+
+fun foo() {
+    @kotlin.jvm.Strictfp class D
+
+    @kotlin.jvm.Strictfp object: Any() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/annotations/targetuse.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/annotations/targetuse.fir.kt
new file mode 100644
index 00000000000..e460ad515b3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/annotations/targetuse.fir.kt
@@ -0,0 +1,21 @@
+// FILE: TargetUse.java
+
+import java.lang.annotation.Target;
+
+public class TargetUse {
+    public static String foo(kotlin.annotation.Target aTarget) {
+        return aTarget.toString();
+    }
+
+    public static String bar(Target aTarget) {
+        return aTarget.toString();
+    }
+}
+
+// FILE: TargetUse.kt
+
+import java.lang.annotation.Target as JTarget
+
+fun fooUse(aTarget: Target): String = TargetUse.foo(aTarget)
+
+fun barUse(aTarget: JTarget): String = TargetUse.bar(aTarget)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/assert/cast.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/assert/cast.fir.kt
new file mode 100644
index 00000000000..11505fccf9a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/assert/cast.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// !IGNORE_DATA_FLOW_IN_ASSERT
+// SKIP_TXT
+// WITH_RUNTIME
+
+interface A {}
+
+class B: A {
+    fun bool() = true
+}
+
+fun test1(a: A) {
+    assert((a as B).bool())
+    a.bool()
+}
+
+fun test2() {
+    val a: A? = null;
+    assert((a as B).bool())
+    a?.bool()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/assert/safeCall.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/assert/safeCall.fir.kt
new file mode 100644
index 00000000000..dbacaa18056
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/assert/safeCall.fir.kt
@@ -0,0 +1,38 @@
+// !WITH_NEW_INFERENCE
+// !IGNORE_DATA_FLOW_IN_ASSERT
+// SKIP_TXT
+// WITH_RUNTIME
+
+fun test1(s: String?) {
+    assert(s!!.isEmpty())
+    s?.length
+}
+
+fun test2(s: String?) {
+    assert(s!!.isEmpty())
+    s!!.length
+}
+
+fun test3(s: String?) {
+    assert(s!!.isEmpty())
+    s.length
+}
+
+fun test4() {
+    val s: String? = null;
+    assert(s!!.isEmpty())
+    s?.length
+}
+
+fun test5() {
+    val s: String? = null;
+    assert(s!!.isEmpty())
+    s!!.length
+}
+
+fun test6() {
+    val s: String? = null;
+    assert(s!!.isEmpty())
+    s.length
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/builtins/arraysAreCloneable.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/builtins/arraysAreCloneable.fir.kt
new file mode 100644
index 00000000000..a0cc68a4eec
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/builtins/arraysAreCloneable.fir.kt
@@ -0,0 +1,25 @@
+// !CHECK_TYPE
+
+fun foo(x: Cloneable) = x
+
+fun test() {
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(arrayOf(""))
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(intArrayOf())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(longArrayOf())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(shortArrayOf())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(byteArrayOf())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(charArrayOf())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(doubleArrayOf())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(floatArrayOf())
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(booleanArrayOf())
+
+    arrayOf("").<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Array<String>>() }
+    intArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><IntArray>() }
+    longArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><LongArray>() }
+    shortArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><ShortArray>() }
+    byteArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><ByteArray>() }
+    charArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><CharArray>() }
+    doubleArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><DoubleArray>() }
+    floatArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><FloatArray>() }
+    booleanArrayOf().<!UNRESOLVED_REFERENCE!>clone<!>() <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><BooleanArray>() }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/cast/AsInsideIn.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/cast/AsInsideIn.fir.kt
new file mode 100644
index 00000000000..7ed4970bc2f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/cast/AsInsideIn.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+// See also KT-10386
+interface A
+class B : A
+fun foo1(list: List<A>, arg: B?): Boolean {
+    // Type mismatch
+    return arg in list // resolved to extension
+}
+fun foo2(list: List<A>, arg: B?): Boolean {
+    // FAKE: no cast needed
+    return arg as A? in list
+}
+fun foo3(list: List<A>, arg: B?): Boolean {
+    // No warning but KNPE risk
+    return arg!! in list
+}
+// But
+fun foo4(list: List<A>, arg: B): Boolean {
+    // Ok
+    return arg in list
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/cast/IsArray.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/cast/IsArray.fir.kt
new file mode 100644
index 00000000000..b2cfa383fc3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/cast/IsArray.fir.kt
@@ -0,0 +1,5 @@
+fun f(a: Array<out Number>) = a.isArrayOf<Int>()
+
+fun f1(a: Array<out Number>) = a is Array<*>
+
+fun f2(a: Array<out Number>) = a is Array<Int>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/cast/IsReified.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/cast/IsReified.fir.kt
new file mode 100644
index 00000000000..7ebb11298d0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/cast/IsReified.fir.kt
@@ -0,0 +1 @@
+fun ff(a: Any) = a is Array<*> && a.isArrayOf<String>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/commonCollections.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/commonCollections.fir.kt
new file mode 100644
index 00000000000..95dad6f9565
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/commonCollections.fir.kt
@@ -0,0 +1,30 @@
+// !WITH_NEW_INFERENCE
+
+import java.util.*
+fun foo() {
+    val al = ArrayList<String>()
+    al.size
+    al.contains(1)
+    al.contains("")
+
+    al.remove("")
+    al.removeAt(1)
+
+    val hs = HashSet<String>()
+    hs.size
+    hs.contains(1)
+    hs.contains("")
+
+    hs.remove("")
+
+
+    val hm = HashMap<String, Int>()
+    hm.size
+    hm.containsKey(1)
+    hm.containsKey("")
+
+    hm[1]
+    hm[""]
+
+    hm.remove("")
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/breakContinuesInInlinedLambda.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/breakContinuesInInlinedLambda.fir.kt
new file mode 100644
index 00000000000..4451a6280ab
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/breakContinuesInInlinedLambda.fir.kt
@@ -0,0 +1,51 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun getBoolean(): Boolean = false
+
+fun test() {
+    val x: Int
+
+    if (getBoolean())
+        myRun {
+            while (getBoolean()) {
+                do {
+                    myRun {
+                        if (getBoolean()) {
+                            x = 42 // No reassignment because of break
+                        }
+                        else {
+                            x = 43 // No reassignment because of break
+                        }
+                    }
+                    break
+                } while (getBoolean())
+                // Loop executed exectly once, initializing x
+                myRun { x.inc() }
+
+                myRun { x = 42 }
+                break
+            }
+            // x is I?D here because loop could've been execited
+            // VAL_REASSIGNMENT isn't reported because of repeating diagnostic
+            x = 42
+            // x is ID now
+        }
+    else
+        myRun {
+            x = 42
+        }
+    // x is ID because both branches are ID
+
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/expressionBody.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/expressionBody.fir.kt
new file mode 100644
index 00000000000..58dd06fbec4
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/expressionBody.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun functionWithExpressionBody(x: Int): Boolean = myRun {
+    if (x == 0) return true
+    if (x == 1) return false
+    return functionWithExpressionBody(x - 2)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/implicitCastToAnyInReturnType.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/implicitCastToAnyInReturnType.fir.kt
new file mode 100644
index 00000000000..5b0f4b45bb1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/implicitCastToAnyInReturnType.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun functionWithSideEffects(x: Int): Int = x + 1 // ...and some other useful side-effects
+
+fun log(s: String) = Unit // some logging or println or whatever returning Unit
+
+fun implicitCastWithIf(s: String) {
+    myRun { if (s == "") functionWithSideEffects(42) else log(s) }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/inlinedLambdaAlwaysThrows.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/inlinedLambdaAlwaysThrows.fir.kt
new file mode 100644
index 00000000000..8ccf5757a7f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/inlinedLambdaAlwaysThrows.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun myRun(block: () -> Unit): Unit {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    block()
+}
+
+fun test() {
+    myRun { throw java.lang.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>() }
+    val x: Int = 42
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/irrelevantUnknownClosure.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/irrelevantUnknownClosure.fir.kt
new file mode 100644
index 00000000000..7f121224199
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/irrelevantUnknownClosure.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun myRun(block: () -> Unit): Unit {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+inline fun unknownRun(block: () -> Unit) { block() }
+
+fun foo() {
+    val x: Int
+    myRun {
+        unknownRun { println("shouldn't change anything") }
+        x = 42
+    }
+    println(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/labeledReturns.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/labeledReturns.fir.kt
new file mode 100644
index 00000000000..93b55158aba
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/labeledReturns.fir.kt
@@ -0,0 +1,86 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+inline fun <T, R> T.myLet(block: (T) -> R): R {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block(this)
+}
+
+inline fun unknownRun(block: () -> Unit) = block()
+
+fun getBool(): Boolean = false
+
+fun threeLevelsReturnNoInitialization(x: Int?): Int? {
+    // Inner always jumps to outer
+    // And middle always calls inner
+    // So, in fact, middle never finished normally
+    // Hence 'y = 54' in middle is unreachable, and middle doesn't performs definite initialization
+    // Hence, outer doesn't performs definite initialization
+    val y: Int
+    myRun outer@ {
+        myRun middle@ {
+            x.myLet inner@ {
+                if (it == null) {
+                    y = 42
+                    return@outer Unit
+                }
+                else {
+                    return@outer Unit
+                }
+            }
+        }
+        // Possible to report unreachable here
+        y = 54
+    }
+    return y.inc()
+}
+
+fun threeLevelsReturnWithInitialization(x: Int?): Int? {
+    val y: Int
+    myRun outer@ {
+        myRun middle@ {
+            x.myLet inner@ {
+                if (it == null) {
+                    y = 42
+                    return@outer Unit
+                }
+                else {
+                    y = 34
+                    return@outer Unit
+                }
+            }
+        }
+    }
+    return y.inc()
+}
+
+fun threeLevelsReturnWithUnknown(x: Int?): Int? {
+    val y: Int
+    myRun outer@ {
+        unknownRun middle@ {
+            x.myLet inner@ {
+                if (it == null) {
+                    y = 42
+                    return@outer Unit
+                }
+                else {
+                    y = 34
+                    return@outer Unit
+                }
+            }
+        }
+    }
+    return y.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nestedTryCatchFinally.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nestedTryCatchFinally.fir.kt
new file mode 100644
index 00000000000..db6eeffc9b5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nestedTryCatchFinally.fir.kt
@@ -0,0 +1,98 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -INVISIBLE_MEMBER -INVISIBLE_REFERENCE
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun innerComputation(): Int = 42
+fun outerComputation(): Int = 52
+
+fun log() = Unit
+
+fun outerFinallyInitializes() {
+    val x: Int
+
+    try {
+        myRun {
+            try {
+                x = innerComputation()
+            } catch (e: java.lang.Exception) {
+                log()
+            }
+            // possible reassignment if innerComputation finished
+            x = 42
+            // x is ID here
+        }
+
+        // Definite reassignment here, cause can get here only if myRun finished
+        // Not reported because of repeating diagnostic
+        x = outerComputation()
+    } catch (e: java.lang.Exception) {
+        // can catch exception thrown by the inner, so x can be not initialized
+        x.inc()
+        log()
+    } finally {
+        // Possible reassignment (e.g. if everything finished)
+        // Not reported because of repeating diagnostic
+        x = 42
+    }
+
+    // Properly initialized
+    x.inc()
+}
+
+fun innerFinallyInitializes() {
+    val x: Int
+    try {
+        myRun {
+            try {
+                innerComputation()
+            } catch (e: java.lang.Exception) {
+                log()
+            } finally {
+                x = 42
+            }
+        }
+
+        // Properly initialized
+        x.inc()
+    } catch (e: java.lang.Exception) {
+        log()
+    }
+
+    // Still can be unitialized because we don't know what can happen in try-block
+    // (e.g., OutOfMemory exception could've happened even before myRun was executed)
+    x.inc()
+}
+
+
+fun innerFinallyInitializesOuterRethrows() {
+    val x: Int
+    try {
+        myRun {
+            try {
+                innerComputation()
+            } catch (e: java.lang.Exception) {
+                log()
+            } finally {
+                x = 42
+            }
+        }
+
+        // Properly initialized
+        x.inc()
+    } catch (e: java.lang.Exception) {
+        log()
+        throw e
+    }
+
+    // Guaranteed to be initialized because all catch-clauses are rethrowing
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nestedTryCatchs.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nestedTryCatchs.fir.kt
new file mode 100644
index 00000000000..af0e303142f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nestedTryCatchs.fir.kt
@@ -0,0 +1,47 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun innerComputation(): Int = 42
+fun outerComputation(): Int = 52
+
+fun innerTryCatchInitializes() {
+    val x: Int
+
+    try {
+        myRun {
+            try {
+                x = innerComputation()
+                x.inc()
+            }
+            catch (e: java.lang.Exception) {
+                // Potential reassignment because x.inc() could threw
+                x = 42
+                x.inc()
+            }
+        }
+        // Can get here only when inlined lambda exited properly, i.e. x is initialized
+        x.inc()
+        outerComputation()
+
+    } catch (e: java.lang.Exception) {
+        // Can get here if innerComputation() threw an exception that wasn't catched by the inner catch (x is not initialized)
+        // OR if outerComputation() threw an exception (x is initialized because we reach outer computation only when inner finished ok)
+        // So, x=I? here
+        x.inc()
+
+        // Potential reasignment
+        x = 42
+    }
+    // Here x=I because outer try-catch either exited normally (x=I) or catched exception (x=I, with reassingment, though)
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nonLocalReturn.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nonLocalReturn.fir.kt
new file mode 100644
index 00000000000..6b5347c24ce
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nonLocalReturn.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T, R> T.myLet(block: (T) -> R): R {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block(this)
+}
+
+
+fun nonLocalReturnWithElvis(x: Int?): Int? {
+    x?.myLet { return 42 }
+    return x?.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nonReturningInlinedLambda.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nonReturningInlinedLambda.fir.kt
new file mode 100644
index 00000000000..c1a05e5289b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/nonReturningInlinedLambda.fir.kt
@@ -0,0 +1,34 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun myRun(block: () -> Unit): Unit {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun getBool(): Boolean = false
+
+fun withLabeledReturn() {
+    val y: Int
+
+    val x = myRun outer@ {
+        myRun { return@outer Unit }
+        y = 42
+    }
+
+    println(y)
+    println(x)
+}
+
+fun withLabeledReturn2(y: Int) {
+    myRun outer@ {
+        myRun { return@outer Unit }
+        println(y)
+    }
+    println(y)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/safeCallAndInPlaceReturn.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/safeCallAndInPlaceReturn.fir.kt
new file mode 100644
index 00000000000..c154232b52f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/safeCallAndInPlaceReturn.fir.kt
@@ -0,0 +1,23 @@
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T> Any?.myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun bad(): String {
+    val x: String? = null
+
+    x?.myRun { return "" }
+}
+
+fun ok(): String {
+    val x: String? = null
+
+    x?.run { return "non-null" } ?: return "null"
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/severalJumpOutsFromInlinedLambda.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/severalJumpOutsFromInlinedLambda.fir.kt
new file mode 100644
index 00000000000..75a48f21ad1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/severalJumpOutsFromInlinedLambda.fir.kt
@@ -0,0 +1,79 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun exitOnlyThroughLocalReturns(b: Boolean) {
+    var x: Int
+    var s: String
+
+    myRun {
+        if (b) {
+            x = 42
+            return@myRun
+        }
+
+        if (!b) {
+            s = "hello"
+            x = 42
+            return@myRun
+        }
+        else {
+            s = "world"
+            x = 239
+        }
+    }
+
+    x.inc()
+    s.length
+}
+
+fun exitOnlyThroughNonLocalReturns(b: Boolean?) {
+    var x: Int
+    var s: String
+    myRun {
+        if (b == null) {
+            x = 42
+            return
+        }
+
+        if (b.not()) {
+            x = 54
+        }
+
+        if (x == 42) {
+            return
+        }
+        else {
+            x = 42
+            s = "hello"
+            return
+        }
+    }
+
+    x.inc()
+    s.length
+}
+
+fun nonLocalReturnAndOrdinaryExit(b: Boolean) {
+    var x: Int
+    var s: String
+    myRun {
+        if (b) {
+            x = 42
+            return
+        }
+        x = 54
+        s = "hello"
+    }
+    x.inc()
+    s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/throwIfNotCalled.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/throwIfNotCalled.fir.kt
new file mode 100644
index 00000000000..326fedbe978
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/throwIfNotCalled.fir.kt
@@ -0,0 +1,48 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun myRun(block: () -> Unit) {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    block()
+}
+
+inline fun <T> unknownRun(block: () -> T): T = block()
+
+fun throwIfNotCalled() {
+    val x: Int
+    myRun outer@ {
+        unknownRun {
+            myRun {
+                x = 42
+                return@outer
+            }
+        }
+        throw java.lang.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>()
+    }
+    // x *is* initialized here, because if myRun was never called -> exception
+    // were thrown and control flow wouldn't be here
+    println(x)
+}
+
+fun catchThrowIfNotCalled() {
+    val x: Int
+    try {
+        myRun outer@ {
+            unknownRun {
+                myRun {
+                    x = 42
+                    return@outer
+                }
+            }
+            throw java.lang.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>()
+        }
+    } catch (ignored: java.lang.IllegalArgumentException) { }
+
+    // x *isn't* initialized here!
+    println(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/tryCatch.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/tryCatch.fir.kt
new file mode 100644
index 00000000000..f616a5fec21
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/tryCatch.fir.kt
@@ -0,0 +1,58 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun someComputation(): Int = 42
+
+fun tryCatchInlined() {
+    val x: Int
+
+    myRun {
+        try {
+            x = someComputation()
+            x.inc()
+        }
+        catch (e: java.lang.Exception) {
+            x.inc()
+        }
+    }
+    x = 42
+    x.inc()
+}
+
+fun possibleReassignmentInTryCatch() {
+    val x: Int
+
+    myRun {
+        try {
+            x = someComputation()
+            x.inc()
+        }
+        catch (e: java.lang.Exception) {
+            x = 42
+            x.inc()
+        }
+        x.inc()
+    }
+    x.inc()
+}
+
+fun tryCatchOuter() {
+    val x: Int
+    try {
+        myRun {  x = someComputation() }
+        x.inc()
+    }
+    catch (e: java.lang.Exception) {
+        x.inc()
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/tryCatchFinally.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/tryCatchFinally.fir.kt
new file mode 100644
index 00000000000..f4f20190699
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/tryCatchFinally.fir.kt
@@ -0,0 +1,34 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER -UNUSED_PARAMETER
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun someComputation(): Int = 42
+
+fun report(x: Int) = Unit
+
+fun innerTryCatchFinally() {
+    val x: Int
+
+    myRun {
+        try {
+            x = someComputation()
+            report(x)
+        } catch (e: java.lang.Exception) {
+            x = 42
+            report(x)
+        } finally {
+            x = 0
+        }
+    }
+
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/typeMismatch.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/typeMismatch.fir.kt
new file mode 100644
index 00000000000..e0015888b81
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/typeMismatch.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun foo(x: Int): Int = x + 1
+
+fun typeMismatchInLambda(y: String): Int {
+    val x = myRun { <!INAPPLICABLE_CANDIDATE!>foo<!>(y) }
+    return x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/unreachableCode.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/unreachableCode.fir.kt
new file mode 100644
index 00000000000..46fa3404a18
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/flowInlining/unreachableCode.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun throwInLambda(): Int {
+    val x = myRun { throw java.lang.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>(); 42 }
+    return x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/valDefiniteReassignment.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/valDefiniteReassignment.fir.kt
new file mode 100644
index 00000000000..0618ddbddf3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/valDefiniteReassignment.fir.kt
@@ -0,0 +1,75 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> runTwice(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.AT_LEAST_ONCE)
+    }
+    block()
+    return block();
+};
+
+fun <T> runOnce(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block();
+};
+
+fun valueReassignment() {
+    val x: Int
+    x.inc()
+    runTwice { x = 42 }
+    x.inc()
+}
+
+fun shadowing() {
+    val x: Int
+    runTwice { val x: Int; x = 42; x.inc() }
+    x.inc()
+}
+
+fun branchingFlow(a: Any?) {
+    val x: Int
+    x.inc()
+    if (a is String) {
+        runTwice { x = 42 }
+    }
+    else {
+        x = 43
+    }
+    x.inc()
+}
+
+fun branchingFlowWithMissingBranches(a: Any?) {
+    val x: Int
+    if (a is String) {
+        runTwice { x = 42 }
+    }
+
+    x.inc()
+}
+
+fun repeatingFlow(n: Int) {
+    val x: Int
+    x.inc()
+
+    for (i in 1..n) {
+        runTwice { x = 42 }
+    }
+
+    x.inc()
+}
+
+fun repeatingFlow2(n: Int) {
+    val x: Int
+
+    for (i in 1..n) {
+        runTwice { x = 42 }
+    }
+
+    x.inc()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/varDefiniteInitialization.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/varDefiniteInitialization.fir.kt
new file mode 100644
index 00000000000..52614a207e6
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/varDefiniteInitialization.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> runTwice(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.AT_LEAST_ONCE)
+    }
+    block()
+    return block();
+};
+
+fun testInitialization() {
+    var x: Int
+    x.inc()
+    runTwice { x = 42 }
+    x.inc()
+    x = 43
+    x.inc()
+}
+
+fun repeatingFlow(n: Int) {
+    var x: Int
+    for (i in 1..n) {
+        runTwice { x = 42 }
+    }
+    x.inc()
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/varIndefiniteIntialization.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/varIndefiniteIntialization.fir.kt
new file mode 100644
index 00000000000..5495be36dbf
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/atLeastOnce/varIndefiniteIntialization.fir.kt
@@ -0,0 +1,29 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> runTwice(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.AT_LEAST_ONCE)
+    }
+    block()
+    return block();
+};
+
+fun <T> funWithUnknownInvocations(block: () -> T) = block()
+
+fun indefiniteFlow() {
+    var x: Int
+
+    funWithUnknownInvocations { runTwice { x = 42 } }
+
+    x.inc()
+}
+
+fun shadowing() {
+    var x: Int
+    runTwice { val x: Int; x = 42; x.inc() }
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valDefiniteInitialization.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valDefiniteInitialization.fir.kt
new file mode 100644
index 00000000000..51af3aa7e9d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valDefiniteInitialization.fir.kt
@@ -0,0 +1,92 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun initialization() {
+    val x: Int
+    myRun {
+        x = 42
+        42
+    }
+    x.inc()
+}
+
+fun shadowing() {
+    val x = 42
+    myRun {
+        val x = 43
+        x.inc()
+    }
+    x.inc()
+}
+
+fun nestedDefiniteAssignment() {
+    val x: Int
+    myRun {
+        val y = "Hello"
+        myRun {
+            x = 42
+        }
+        y.length
+    }
+    x.inc()
+}
+
+fun deeplyNestedDefiniteAssignment() {
+    val x: Int
+    myRun {
+        val y: String
+        myRun {
+            val z: String
+            myRun {
+                z = "Hello"
+                y = "World"
+                x = 42
+            }
+            z.length
+        }
+        y.length
+    }
+    x.inc()
+}
+
+fun branchingFlow(a: Any?) {
+    val x: Int
+
+    if (a is String) {
+        myRun { x = 42 }
+    }
+    else {
+        myRun { x = 43 }
+    }
+
+    x.inc()
+}
+
+fun returningValue() {
+    val x: Int
+    val hello = myRun { x = 42; "hello" }
+    x.inc()
+    hello.length
+}
+
+fun unknownRun(block: () -> Unit) = block()
+
+class DefiniteInitializationInInitSection {
+    val x: Int
+    val y: Int
+
+    init {
+        myRun { x = 42 }
+        unknownRun { y = 239 }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valDefiniteReassignment.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valDefiniteReassignment.fir.kt
new file mode 100644
index 00000000000..facb05750e3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valDefiniteReassignment.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun reassignmentInUsualFlow() {
+    val x: Int
+    myRun { x = 42 }
+    x = 43
+    x.inc()
+}
+
+fun reassignment() {
+    val x = 42
+    myRun {
+        x = 43
+    }
+    x.inc()
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valIndefiniteInitialization.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valIndefiniteInitialization.fir.kt
new file mode 100644
index 00000000000..f8189380d92
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valIndefiniteInitialization.fir.kt
@@ -0,0 +1,68 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun myRepeat(n: Int, action: () -> Unit) {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(action)
+    }
+    for (i in 1..n) action()
+}
+
+fun branchingIndetermineFlow(a: Any?) {
+    val x: Int
+
+    if (a is String) {
+        myRepeat(a.length) {
+            // Val reassignment because we know that repeat's lambda called in-place
+            myRun { x = 42 }
+        }
+    }
+    else {
+        myRun { x = 43 }
+    }
+
+    x.inc()
+}
+
+fun nonAnonymousLambdas() {
+    val x: Int
+    val initializer = { x = 42 }
+    myRun(initializer)
+    x.inc()
+}
+
+fun multipleAssignments() {
+    val x: Int
+    myRepeat(42) {
+        // Val reassignment because we know that repeat's lambda called in-place
+        myRun { x = 42 }
+    }
+    x.inc()
+}
+
+fun funWithUnknownInvocations(block: () -> Unit) = block()
+
+fun nestedIndefiniteAssignment() {
+    val x: Int
+    // Captured val initialization reported, because we don't know anything about funWithUnknownInvocations
+    funWithUnknownInvocations { myRun { x = 42 } }
+    x.inc()
+}
+
+class InitializationForbiddenInNonInitSection {
+    val x: Int
+
+    fun setup() {
+        myRun { x = 42 }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/varDefiniteInitalization.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/varDefiniteInitalization.fir.kt
new file mode 100644
index 00000000000..a8f603bad54
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/varDefiniteInitalization.fir.kt
@@ -0,0 +1,42 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun definiteVarInitialization() {
+    var x: Int
+    myRun { x = 42 }
+    x.inc()
+}
+
+fun definiteVarReassignment() {
+    var x: Int
+    myRun { x = 42 }
+    x.inc()
+    myRun { x = 43 }
+    x.inc()
+    x = 44
+    x.inc()
+}
+
+fun nestedVarInitialization() {
+    var x: Int
+    myRun { myRun { myRun { x = 42 } } }
+    x.inc()
+    myRun { myRun { myRun { x = 42 } } }
+}
+
+
+fun notAnExpression() {
+    var x: Int = 0
+    myRun { if (true) x = 42 }
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/varIndefiniteInitialization.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/varIndefiniteInitialization.fir.kt
new file mode 100644
index 00000000000..0c426acd468
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/varIndefiniteInitialization.fir.kt
@@ -0,0 +1,51 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> myRun(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block()
+}
+
+fun indefiniteVarReassignment(n: Int) {
+    var x: Int
+    repeat(n) {
+        myRun { x = 42 }
+    }
+    x.inc()
+}
+
+fun nonAnonymousLambdas() {
+    // Named lambdas are not inlined, even in theory it could be done for some simple cases as this one
+    var x: Int
+    val initializer = { x = 42 }
+    myRun(initializer)
+    x.inc()
+}
+
+fun branchingIndetermineFlow(a: Any) {
+    var x: Int
+
+    if (a is String) {
+        repeat(a.length) {
+            myRun { x = 42 }
+        }
+    }
+    else {
+        myRun { x = 43 }
+    }
+
+    x.inc()
+}
+
+fun funWithUnknownInvocations(block: () -> Unit) = block()
+
+fun nestedIndefiniteAssignment() {
+    val x: Int
+    funWithUnknownInvocations { myRun { x = 42 } }
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/withReceiver.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/withReceiver.fir.kt
new file mode 100644
index 00000000000..d6874031a9b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/withReceiver.fir.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T, R> T.myLet(block: (T) -> R): R {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    return block(this)
+}
+
+fun initializationWithReceiver(y: String) {
+    val x: Int
+    y.myLet { x = 42 }
+    x.inc()
+}
+
+fun initializationWithSafeCall(y: String?) {
+    val x: Int
+    y?.myLet { x = 42 }
+    x.inc()
+}
+
+fun sanityCheck(x: Int, y: String): Int {
+    y.let { return x }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/unknown/unknownInvocations.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/unknown/unknownInvocations.fir.kt
new file mode 100644
index 00000000000..31a9ce473a5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/unknown/unknownInvocations.fir.kt
@@ -0,0 +1,18 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun <T> inPlace(block: () -> T): T {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block)
+    }
+    return block()
+}
+
+fun reassignmentAndNoInitializaiton() {
+    val x: Int
+    inPlace { x = 42 }
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/callUsualContractFunction.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/callUsualContractFunction.fir.kt
new file mode 100644
index 00000000000..1c03aa81914
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/callUsualContractFunction.fir.kt
@@ -0,0 +1,42 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+package my
+
+// Accepts block, can't be distinguished from kotlin.contract without resolve
+fun contract(block: () -> Unit) {}
+
+// Accepts int, potentially can be distinguished from kotlin.contract by PSI,
+// but as of Kotlin 1.3.0, we don't do that
+fun contract(i: Int) {}
+
+fun doStuff() {}
+
+class SomeClass {
+
+    fun contract() {}
+
+    fun callMemberContractWithThis() {
+        this.contract()
+    }
+
+    fun callMemberContractWithoutThis() {
+        contract()
+    }
+
+    fun callTopLevelSamePsiInMember() {
+        contract { }
+    }
+}
+
+fun callTopLevelSamePsi() {
+    contract { }
+}
+
+fun callTopLevelDifferentPsi() {
+    contract(42)
+}
+
+fun callTopLevelSamePsiNotFirstStatement() {
+    doStuff()
+    contract { }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/booleanComparisons.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/booleanComparisons.fir.kt
new file mode 100644
index 00000000000..c0c46f6f189
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/booleanComparisons.fir.kt
@@ -0,0 +1,23 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun foo(b: Boolean): Boolean {
+    contract {
+        // pointless, can be reduced to just "b"
+        returns(true) implies (b == true)
+    }
+
+    return b
+}
+
+fun bar(b: Boolean?): Boolean {
+    contract {
+        // not pointless, but not supported yet
+        returns(true) implies (b == true)
+    }
+    if (b == null) throw java.lang.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>("")
+    return b
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/callInContractDescription.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/callInContractDescription.fir.kt
new file mode 100644
index 00000000000..a4bf44632ad
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/callInContractDescription.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun bar(x: Int): Boolean = x == 0
+
+fun foo(x: Int): Boolean {
+    contract {
+        returns(true) implies (bar(x))
+    }
+    return x == 0
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/contractCallSites.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/contractCallSites.fir.kt
new file mode 100644
index 00000000000..b90ac27984b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/contractCallSites.fir.kt
@@ -0,0 +1,86 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER -NOTHING_TO_INLINE -ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS -ABSTRACT_FUNCTION_WITH_BODY -UNUSED_PARAMETER -UNUSED_VARIABLE -EXPERIMENTAL_FEATURE_WARNING
+
+import kotlin.contracts.*
+
+
+// ============= Class =====================
+open class Class {
+    fun member(x: Boolean) {
+        contract { returns() implies (x) }
+    }
+    
+    inline fun inlineMember(x: Boolean) {
+        contract { returns() implies (x) }
+    }
+    
+    abstract fun abstractMember(x: Boolean) {
+        contract { returns() implies (x) }
+    }
+    
+    open fun openMemeber(x: Boolean) {
+        contract { returns() implies (x) }
+    }
+    
+    suspend fun suspendMember(x: Boolean) {
+        contract { returns() implies (x) }
+    }
+}
+
+
+// ============= Top-level =====================
+fun topLevel(x: Boolean) {
+    contract { returns() implies (x) }
+}
+
+inline fun inlineTopLevel(x: Boolean) {
+    contract { returns() implies (x) }
+}
+
+suspend fun suspendTopLevel(x: Boolean) {
+    contract { returns() implies (x) }
+}
+
+// Top-level operator
+operator fun Boolean.plus(x: Boolean): Boolean {
+    contract { returns() implies (x) }
+    return x
+}
+
+val topLevelLambda: (Boolean) -> Unit = { x: Boolean ->
+    contract { returns() implies (x) }
+}
+
+val topLevelAnonymousFunction = fun (x: Boolean) {
+    contract { returns() implies (x) }
+}
+
+var topLevelPropertyAccessors: Int? = 42
+    get() {
+        contract { returns() implies (field != null) }
+        return 42
+    }
+    set(value) {
+        contract { returns() implies (field != null) }
+    }
+
+
+// ============= Local =====================
+fun test() {
+    fun localDeclaration(x: Boolean) {
+        contract { returns() implies (x) }
+    }
+
+    suspend fun suspendlocalDeclaration(x: Boolean) {
+        contract { returns() implies (x) }
+    }
+
+    val localAnonymousFunction = fun (x: Boolean) {
+        contract { returns() implies (x) }
+    }
+
+    val localLambda: (Boolean) -> Unit = { x: Boolean ->
+        contract { returns() implies (x) }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/emptyContract.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/emptyContract.fir.kt
new file mode 100644
index 00000000000..eaed628ce7b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/emptyContract.fir.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun emptyContract() {
+    contract { }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/illegalConstructionInContractBlock.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/illegalConstructionInContractBlock.fir.kt
new file mode 100644
index 00000000000..e4745964d0a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/illegalConstructionInContractBlock.fir.kt
@@ -0,0 +1,55 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER -NOTHING_TO_INLINE -ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS -ABSTRACT_FUNCTION_WITH_BODY -UNUSED_PARAMETER -UNUSED_VARIABLE -EXPERIMENTAL_FEATURE_WARNING
+
+import kotlin.contracts.*
+
+fun ifInContract(x: Any?, boolean: Boolean) {
+    contract {
+        if (boolean) {
+            returns() implies (x is String)
+        } else {
+            returns() implies (x is Int)
+        }
+    }
+}
+
+fun whenInContract(x: Any?, boolean: Boolean) {
+    contract {
+        when (boolean) {
+            true -> returns() implies (x is String)
+            else -> returns() implies (x is Int)
+        }
+    }
+}
+
+fun forInContract(x: Any?) {
+    contract {
+        for (i in 0..1) {
+            returns() implies (x is String)
+        }
+    }
+}
+
+fun whileInContract(x: Any?) {
+    contract {
+        while (false) {
+            returns() implies (x is String)
+        }
+    }
+}
+
+fun doWhileInContract(x: Any?) {
+    contract {
+        do {
+            returns() implies (x is String)
+        } while (false)
+    }
+}
+
+fun localValInContract(x: Any?) {
+    contract {
+        val y: Int = 42
+        returns() implies (x is String)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/illegalEqualsCondition.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/illegalEqualsCondition.fir.kt
new file mode 100644
index 00000000000..7648c66f380
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/illegalEqualsCondition.fir.kt
@@ -0,0 +1,30 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun equalsWithVariables(x: Any?, y: Any?) {
+    contract {
+        returns() implies (x == y)
+    }
+}
+
+fun identityEqualsWithVariables(x: Any?, y: Any?) {
+    contract {
+        returns() implies (x === y)
+    }
+}
+
+fun equalConstants() {
+    contract {
+        returns() implies (null == null)
+    }
+}
+
+fun get(): Int? = null
+fun equalNullWithCall() {
+    contract {
+        returns() implies (get() == null)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/nestedConditionalEffects.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/nestedConditionalEffects.fir.kt
new file mode 100644
index 00000000000..355fe9efdea
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/nestedConditionalEffects.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun foo(boolean: Boolean) {
+    contract {
+        (returns() implies (boolean)) <!UNRESOLVED_REFERENCE!>implies<!> (!boolean)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/nonLambdaLiteralAsArgument.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/nonLambdaLiteralAsArgument.fir.kt
new file mode 100644
index 00000000000..8744ec7d62e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/nonLambdaLiteralAsArgument.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER -EXPOSED_PARAMETER_TYPE
+
+import kotlin.contracts.*
+
+fun passLambdaValue(l: ContractBuilder.() -> Unit) {
+    contract(l)
+}
+
+fun passAnonymousFunction(x: Boolean) {
+    contract(fun ContractBuilder.() {
+        <!UNRESOLVED_REFERENCE!>returns<!>() <!UNRESOLVED_REFERENCE!>implies<!> x
+    })
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/notFirstStatement.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/notFirstStatement.fir.kt
new file mode 100644
index 00000000000..9ac8ce1004c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/notFirstStatement.fir.kt
@@ -0,0 +1,76 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER -UNUSED_VARIABLE -REDUNDANT_LABEL_WARNING -UNUSED_PARAMETER -NOTHING_TO_INLINE -CAST_NEVER_SUCCEEDS
+// Issues: KT-26153, KT-26191
+
+import kotlin.contracts.*
+
+fun foo(y: Boolean) {
+    val x: Int = 42
+    contract {
+        returns() implies y
+    }
+}
+
+inline fun case1(block: () -> Unit) {
+    val contracts = listOf(
+        contract {
+            <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+        }, contract {
+            <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+        }
+    )
+    block()
+}
+
+inline fun case_2(block: () -> Unit) = contract {
+    <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+}
+
+fun case_3(block: () -> Unit) {
+    class Class {
+        fun innerFun(block2: () -> Unit) {
+            contract {
+                <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block2, InvocationKind.EXACTLY_ONCE)
+            }
+            block2()
+        }
+    }
+    return
+}
+
+inline fun case_4(number: Int?): Boolean {
+    val cond = number != null
+    contract {
+        returns(false) implies (cond)
+    } as ContractBuilder
+    return number == null
+}
+
+inline fun case_5(cond: Boolean): Boolean {
+    run {
+        contract {
+            returns(true) implies (cond)
+        }
+    }
+    return true
+}
+
+inline fun case_6(cond: Boolean): Boolean {
+    run {
+        val x = 10
+        contract {
+            returns(true) implies (cond)
+        }
+    }
+    return true
+}
+
+fun case_7(cond: Boolean): Boolean {
+    fun innerFun() {
+        contract {
+            returns(true) implies (cond)
+        }
+    }
+    return true
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/recursiveContract.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/recursiveContract.fir.kt
new file mode 100644
index 00000000000..457ee97992e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/recursiveContract.fir.kt
@@ -0,0 +1,25 @@
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !LANGUAGE: +UseReturnsEffect
+// Issue: KT-26386
+
+import kotlin.contracts.*
+
+fun case_1(): Boolean {
+    contract { returns(null) implies case_1() }
+    return true
+}
+
+fun case_2(): Boolean {
+    contract { returns(null) implies case_3() }
+    return true
+}
+
+fun case_3(): Boolean {
+    contract { returns(null) implies case_2() }
+    return true
+}
+
+fun case_4(): Boolean {
+    kotlin.contracts.contract { returns(null) implies case_1() }
+    return true
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/recursiveContractCustomContractFunction.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/recursiveContractCustomContractFunction.fir.kt
new file mode 100644
index 00000000000..1b57f6a6d0f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/recursiveContractCustomContractFunction.fir.kt
@@ -0,0 +1,39 @@
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !LANGUAGE: +UseReturnsEffect
+// Issue: KT-26386
+
+fun myRun(block: () -> Unit) {
+    block()
+}
+
+fun contract(block: () -> Unit) {
+    block()
+}
+
+fun case_1(): Boolean? {
+    contract { case_1() }
+    return null
+}
+
+fun case_2(): Boolean? {
+    contract { case_3() }
+    return null
+}
+
+fun case_3(): Boolean? {
+    contract { case_2() }
+    return null
+}
+
+fun case4() {
+    contract {
+        myRun {
+            val s: String
+            run {
+                s = "hello"
+            }
+            s.length
+        }
+    }
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/referenceToProperty.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/referenceToProperty.fir.kt
new file mode 100644
index 00000000000..59f6cc5db43
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/referenceToProperty.fir.kt
@@ -0,0 +1,14 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+class Foo(val x: Int?) {
+    fun isXNull(): Boolean {
+        contract {
+            returns(false) implies (x != null)
+        }
+        return x != null
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/typeReferences.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/typeReferences.fir.kt
new file mode 100644
index 00000000000..54e338c282f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/typeReferences.fir.kt
@@ -0,0 +1,53 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+inline fun <reified T> referToReifiedGeneric(x: Any?) {
+    contract {
+        returns() implies (x is T)
+    }
+}
+
+class Generic<T> {
+    fun referToCaptured(x: Any?) {
+        contract {
+            returns() implies (x is T)
+        }
+    }
+}
+
+fun referToSubstituted(x: Any?) {
+    contract {
+        returns() implies (x is Generic<String>)
+    }
+}
+
+fun referToSubstitutedWithStar(x: Any?) {
+    contract {
+        returns() implies (x is Generic<*>)
+    }
+}
+
+typealias GenericString = Generic<String>
+typealias FunctionalType = () -> Unit
+typealias SimpleType = Int
+
+fun referToAliasedGeneric(x: Any?) {
+    contract {
+        returns() implies (x is GenericString)
+    }
+}
+
+fun referToAliasedFunctionType(x: Any?) {
+    contract {
+        returns() implies (x is FunctionalType)
+    }
+}
+
+fun referToAliasedSimpleType(x: Any?) {
+    contract {
+        returns() implies (x is SimpleType)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/unlabeledReceiver.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/unlabeledReceiver.fir.kt
new file mode 100644
index 00000000000..51f0c4965ac
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/unlabeledReceiver.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun Any?.foo(): Boolean {
+    contract {
+        returns(true) implies (this != null)
+    }
+    return this != null
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/fqnContractFunction.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/fqnContractFunction.fir.kt
new file mode 100644
index 00000000000..12a37c7caf5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/fqnContractFunction.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.InvocationKind
+
+inline fun foo(block: () -> Unit) {
+    kotlin.contracts.contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+    }
+    block()
+}
+
+fun main() {
+    val x: Int
+    foo {
+        x = 42
+    }
+    println(x)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/rewriteAtSliceFunctor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/rewriteAtSliceFunctor.fir.kt
new file mode 100644
index 00000000000..4942fcb9448
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/rewriteAtSliceFunctor.fir.kt
@@ -0,0 +1,10 @@
+// See KT-28847
+
+class Foo(val str: String?) {
+    val first = run {
+        str.isNullOrEmpty()
+        second
+    }
+
+    val second = str.isNullOrEmpty()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/useBeforeDeclaration.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/useBeforeDeclaration.fir.kt
new file mode 100644
index 00000000000..55a1532bced
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/useBeforeDeclaration.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+
+import kotlin.contracts.*
+
+fun test(x: Any?) {
+    if (isString(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/check.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/check.fir.kt
new file mode 100644
index 00000000000..c995b305d84
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/check.fir.kt
@@ -0,0 +1,33 @@
+// !LANGUAGE: +ReadDeserializedContracts +UseReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+fun testCheckSmartcast(x: Any?) {
+    check(x is String)
+    x.length
+}
+
+fun testCheckUnreachableCode() {
+    check(false)
+    // Can't be reported without notion of 'iff'
+    println("Can't get here!")
+}
+
+fun testCheckWithMessage(x: Any?) {
+    check(x is String) { "x is not String!" }
+    x.length
+}
+
+fun testCheckWithFailingMessage(x: Any?) {
+    check(x is String) { throw kotlin.<!UNRESOLVED_REFERENCE!>IllegalStateException<!>("What a strange idea") }
+    x.length
+}
+
+fun testCheckNotNullWithMessage(x: Int?) {
+    checkNotNull(x) { "x is null!" }
+    x.inc()
+}
+
+fun testCheckNotNull(x: Int?) {
+    checkNotNull(x)
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/fromStandardKt.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/fromStandardKt.fir.kt
new file mode 100644
index 00000000000..19704fd1dcd
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/fromStandardKt.fir.kt
@@ -0,0 +1,110 @@
+// !LANGUAGE: +ReadDeserializedContracts +UseCallsInPlaceEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+fun testRunWithUnitReturn() {
+    val x: Int
+    run { x  = 42 }
+    println(x)
+}
+
+fun testRunWithReturnValue() {
+    val x: Int
+    val y = run {
+        x = 42
+        "hello"
+    }
+    println(x)
+    println(y)
+}
+
+fun testRunWithCoercionToUnit() {
+    val x: Int
+    run {
+        x = 42
+        "hello"
+    }
+}
+
+fun testRunWithReceiver(x: Int) {
+    val s: String
+    x.run {
+        s = this.toString()
+    }
+    println(s)
+}
+
+fun testWith(x: Int) {
+    val s: String
+    with(x) {
+        s = toString()
+    }
+    println(s)
+}
+
+fun testApply(x: Int) {
+    val y: Int
+    val z: Int = x.apply { y = 42 }
+    println(y)
+    println(z)
+}
+
+fun testAlso(x: Int) {
+    val y: Int
+    x.also { y = it + 1 }
+    println(y)
+}
+
+fun testLet(x: Int) {
+    val z: Int
+    val y: String = x.let {
+        z = 42
+        (it + 1).toString()
+    }
+    println(z)
+    println(y)
+}
+
+fun testTakeIf(x: Int?) {
+    val y: Int
+    x.takeIf {
+        y = 42
+        it != null
+    }
+    println(y)
+}
+
+fun testTakeUnless(x: Int?) {
+    val y: Int
+    x.takeIf {
+        y = 42
+        it != null
+    }
+    println(y)
+}
+
+fun testRepeatOnVal(x: Int) {
+    val y: Int
+    repeat(x) {
+        // reassignment instead of captured val initialization
+        y = 42
+    }
+    println(y)
+}
+
+fun testRepeatOnVar(x: Int) {
+    var y: Int
+    repeat(x) {
+        // no reassignment reported
+        y = 42
+    }
+    // but here we still unsure if 'y' was initialized
+    println(y)
+}
+
+fun testRepeatOnInitializedVar(x: Int) {
+    var y: Int = 24
+    repeat(x) {
+        y = 42
+    }
+    println(y)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrBlank.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrBlank.fir.kt
new file mode 100644
index 00000000000..40960b5b21e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrBlank.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +ReadDeserializedContracts +UseReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+fun testIsNullOrBlank(x: String?) {
+    if (x.isNullOrBlank()) {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    else {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
+
+fun testIsNotNullOrBlank(x: String?) {
+    if (!x.isNullOrBlank()) {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+
+    x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrEmpty.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrEmpty.fir.kt
new file mode 100644
index 00000000000..f33d9520b95
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrEmpty.fir.kt
@@ -0,0 +1,20 @@
+// !LANGUAGE: +ReadDeserializedContracts +UseReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+fun testIsNullOrEmpty(x: String?) {
+    if (x.isNullOrEmpty()) {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+    else {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
+
+fun testIsNotNullOrEmpty(x: String?) {
+    if (!x.isNullOrEmpty()) {
+        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+
+    x.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/require.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/require.fir.kt
new file mode 100644
index 00000000000..69c93de9dab
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/require.fir.kt
@@ -0,0 +1,27 @@
+// !LANGUAGE: +ReadDeserializedContracts +UseReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+fun testRequireSmartcast(x: Any?) {
+    require(x is String)
+    x.length
+}
+
+fun testRequireUnreachableCode() {
+    require(false)
+    println("Can't get here!")
+}
+
+fun testRequireWithMessage(x: Any?) {
+    require(x is String) { "x is not String!" }
+    x.length
+}
+
+fun testRequireWithFailingMessage(x: Any?) {
+    require(x is String) { throw kotlin.<!UNRESOLVED_REFERENCE!>IllegalStateException<!>("What a strange idea") }
+    x.length
+}
+
+fun tesRequireNotNullWithMessage(x: Int?) {
+    requireNotNull(x) { "x is null!"}
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/synchronize.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/synchronize.fir.kt
new file mode 100644
index 00000000000..7af925daf1b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/synchronize.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +ReadDeserializedContracts +UseCallsInPlaceEffect
+
+fun test(lock: Any) {
+    val x: Int
+
+    synchronized(lock) {
+        x = 42
+    }
+
+    x.inc()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/callWithDefaultValue.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/callWithDefaultValue.fir.kt
new file mode 100644
index 00000000000..5a9eb941860
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/callWithDefaultValue.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun myAssert(condition: Boolean, message: String = "") {
+    contract {
+        returns() implies (condition)
+    }
+    if (!condition) throw kotlin.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>(message)
+}
+
+fun test(x: Any?) {
+    myAssert(x is String)
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/catchExceptionSpilling.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/catchExceptionSpilling.fir.kt
new file mode 100644
index 00000000000..1ff2a9cb789
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/catchExceptionSpilling.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun myAssert(condition: Boolean) {
+    contract {
+        returns() implies (condition)
+    }
+    if (!condition) throw kotlin.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>("Assertion failed")
+}
+
+fun testWithCatch(x: Any?) {
+    try {
+        myAssert(x is String)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    } catch (e: java.lang.IllegalArgumentException) { }
+
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/compositions.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/compositions.fir.kt
new file mode 100644
index 00000000000..63f22fe0615
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/compositions.fir.kt
@@ -0,0 +1,70 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun testEqualsWithConstant(x: Any?) {
+    if (isString(x) == true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun testNotEqualsWithConstant(x: Any?) {
+    if (isString(x) != true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun unknownFunction(): Any? = 42
+
+fun testEqualsWithUnknown(x: Any?) {
+    if (isString(x) == unknownFunction()) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testNotEqualsWithUnknown(x: Any?) {
+    if (isString(x) != unknownFunction()) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testEqualsWithVariable(x: Any?, b: Boolean) {
+    if (isString(x) == b) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun testNotEqualsWithVariable(x: Any?, b: Boolean) {
+    if (isString(x) != b) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/deeplyNested.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/deeplyNested.fir.kt
new file mode 100644
index 00000000000..547e0691f2c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/deeplyNested.fir.kt
@@ -0,0 +1,104 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun myAssert(condition: Boolean) {
+    contract {
+        returns() implies (condition)
+    }
+    if (!condition) throw kotlin.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>("Assertion failed")
+}
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun isInt(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is Int)
+    }
+    return x is Int
+}
+
+fun notEqualsNull(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x != null)
+    }
+    return x != null
+}
+
+fun equalsTrue(x: Boolean): Boolean {
+    contract {
+        returns(true) implies x
+    }
+    return x == true
+}
+
+fun nullWhenNotString(x: Any?): String? {
+    contract {
+        returnsNotNull() implies (x is String)
+    }
+    return x as? String
+}
+
+
+
+
+// ========== Actual tests ============
+
+fun nested1(x: Any?) {
+    if (equalsTrue(isString(x))) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun nested2(x: Any?) {
+    myAssert(equalsTrue(isString(x)))
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun nested3(x: Any?) {
+    myAssert(equalsTrue(notEqualsNull(nullWhenNotString(x))))
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun branchedAndNested(x: Any?, y: Any?) {
+    myAssert(equalsTrue(notEqualsNull(nullWhenNotString(x))) && equalsTrue(isString(y)))
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+    y.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+
+fun br(y: Any?) {
+    if (myAssert(y is Int) == Unit && myAssert(y is String) == Unit) {
+        y.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun branchedAndNestedWithNativeOperators(x: Any?, y: Any?) {
+    myAssert(
+            equalsTrue(notEqualsNull(nullWhenNotString(x)))   // x is String
+            &&
+            (
+                    (myAssert(y is Int) == Unit && myAssert(y is String) == Unit)  // y is Int, String
+                    ||
+                    equalsTrue(isInt(y) && isString(y))                          // y is Int, String
+            )
+            &&
+            (1 == 2 || y is Int || isString(y))
+    )
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+    y.<!UNRESOLVED_REFERENCE!>length<!>
+    y.<!AMBIGUITY!>inc<!>()
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver.fir.kt
new file mode 100644
index 00000000000..809b6ab375b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver.fir.kt
@@ -0,0 +1,38 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+//
+// ISSUE: KT-28672
+
+import kotlin.contracts.*
+
+fun CharSequence?.isNullOrEmpty(): Boolean {
+    contract {
+        returns(false) implies (this@isNullOrEmpty != null)
+    }
+
+    return this == null || this.length == 0
+}
+
+fun smartcastOnReceiver(s: String?) {
+    with(s) {
+        if (isNullOrEmpty()) {
+            length
+        }
+        else {
+            length
+        }
+    }
+}
+
+fun mixedReceiver(s: String?) {
+    if (!s.isNullOrEmpty()) {
+        with(s) {
+            length
+        }
+    } else {
+        with(s) {
+            length
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver_after.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver_after.fir.kt
new file mode 100644
index 00000000000..d0ba672130a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver_after.fir.kt
@@ -0,0 +1,38 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect +ContractsOnCallsWithImplicitReceiver
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+//
+// ISSUE: KT-28672
+
+import kotlin.contracts.*
+
+fun CharSequence?.isNullOrEmpty(): Boolean {
+    contract {
+        returns(false) implies (this@isNullOrEmpty != null)
+    }
+
+    return this == null || this.length == 0
+}
+
+fun smartcastOnReceiver(s: String?) {
+    with(s) {
+        if (isNullOrEmpty()) {
+            length
+        }
+        else {
+            length
+        }
+    }
+}
+
+fun mixedReceiver(s: String?) {
+    if (!s.isNullOrEmpty()) {
+        with(s) {
+            length
+        }
+    } else {
+        with(s) {
+            length
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/intersectingInfo.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/intersectingInfo.fir.kt
new file mode 100644
index 00000000000..36be683de7a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/intersectingInfo.fir.kt
@@ -0,0 +1,61 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+
+fun notIsString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun notIsInt(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x !is Int)
+    }
+    return x !is Int
+}
+
+fun intersectingInfo(x: Any?, y: Any?) {
+    if ((isString(x) && y is String) || (!notIsString(x) && !notIsInt(y))) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun intersectingInfo2(x: Any?, y: Any?) {
+    // In each arg of "||"-operator presented fact "x is String" which should lead to smartcast.
+    // Also there are 3 additional facts: "x is Int", "y is String", "y is Int". One
+    // of them is absent in each arg of "||"-operator, so they *shouldn't* lead to smartcast
+
+    if ((isString(x) && !notIsInt(x) && y is String) ||
+        (!notIsString(x) && isString(y) && y is Int) ||
+        (x is String && !notIsInt(y) && x is Int)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+        y.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!AMBIGUITY!>inc<!>()
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+    x.<!AMBIGUITY!>inc<!>()
+    y.<!UNRESOLVED_REFERENCE!>length<!>
+    y.<!AMBIGUITY!>inc<!>()
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/intersectionTypes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/intersectionTypes.fir.kt
new file mode 100644
index 00000000000..145c2eae9bd
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/intersectionTypes.fir.kt
@@ -0,0 +1,45 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun notIsString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun notIsInt(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is Int)
+    }
+    return x !is Int
+}
+
+fun testDeMorgan(x: Any?) {
+       // !(x !is String || x !is Int)
+       // x is String && x is Int
+    if (!(notIsString(x) || notIsInt(x))) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun testDeMorgan2(x: Any?) {
+        // x !is String || x !is Int
+    if (notIsString(x) || notIsInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/multieffect/implicitIff.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/multieffect/implicitIff.fir.kt
new file mode 100644
index 00000000000..e9d58ce0f67
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/multieffect/implicitIff.fir.kt
@@ -0,0 +1,87 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun onlyTrue(b: Boolean): Boolean {
+    contract {
+        returns(true) implies (b)
+    }
+    return b
+}
+
+fun onlyFalse(b: Boolean): Boolean {
+    contract {
+        returns(false) implies (!b)
+    }
+    return b
+}
+
+fun trueAndFalse(b: Boolean): Boolean {
+    contract {
+        returns(true) implies (b)
+        returns(false) implies (!b)
+    }
+    return b
+}
+
+
+
+// ==== actual tests ====
+
+fun useOnlyTrueInTrueBranch(x: Any?) {
+    if (onlyTrue(x is String)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun useOnlyTrueInFalseBranch(x: Any?) {
+    if (onlyTrue(x !is String)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        // No smartcast here, we don't know that condition is false here
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun useOnlyFalseInTrueBranch(x: Any?) {
+    if (onlyFalse(x is String)) {
+        // No smartcast here, we don't know that condition is true here
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun useOnlyFalseInFalseBranch(x: Any?) {
+    if (onlyFalse(x !is String)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun useTrueAndFalseInTrueBranch(x: Any?) {
+    if (trueAndFalse(x is String)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun useTrueAndFalseInFalseBranch(x: Any?) {
+    if (trueAndFalse(x !is String)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/multieffect/returnsAndCalls.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/multieffect/returnsAndCalls.fir.kt
new file mode 100644
index 00000000000..003741e33ad
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/multieffect/returnsAndCalls.fir.kt
@@ -0,0 +1,68 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect +UseCallsInPlaceEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun callsAndInverts(b: Boolean, block: () -> Unit): Boolean {
+    contract {
+        <!INAPPLICABLE_CANDIDATE!>callsInPlace<!>(block, InvocationKind.EXACTLY_ONCE)
+        returns(true) implies (!b)
+        returns(false) implies b
+    }
+
+    block()
+    return !b
+}
+
+
+
+fun smartcastAndInitialization(x: Any?) {
+    val y: Int
+
+    if (callsAndInverts(x !is String) { y = 42 }) {
+        println(y)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    } else {
+        println(y)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    println(y)
+}
+
+fun inPresenceOfLazy(x: Any?, unknownBoolean: Boolean) {
+    val y: Int
+
+    if (unknownBoolean && callsAndInverts(x !is String) { y = 42 }) {
+        println(y)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        println(y)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    println(y)
+}
+
+fun isPresenceOfLazy2(x: Any?, unknownBoolean: Boolean) {
+    val y: Int
+    if (unknownBoolean && callsAndInverts(x !is String) { y = 42 }) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        println(y)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    println(y)
+}
+
+fun isPresenceOfLazy3(x: Any?, unknownBoolean: Boolean) {
+    val y: Int
+    if (unknownBoolean && callsAndInverts(x !is String) { y = 42 }) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    println(y)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/nullabilitySmartcastWhenNullability.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/nullabilitySmartcastWhenNullability.fir.kt
new file mode 100644
index 00000000000..f91f8ddd50a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/nullabilitySmartcastWhenNullability.fir.kt
@@ -0,0 +1,57 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun nullWhenNull(x: Int?): Int? {
+    contract {
+        returnsNotNull() implies (x != null)
+    }
+    return x?.inc()
+}
+
+fun testNullWhenNull(x: Int?) {
+    if (nullWhenNull(x) == null) {
+        x.<!AMBIGUITY!>dec<!>()
+    }
+    else {
+        x.<!AMBIGUITY!>dec<!>()
+    }
+
+    if (nullWhenNull(x) != null) {
+        x.<!AMBIGUITY!>dec<!>()
+    }
+    else {
+        x.<!AMBIGUITY!>dec<!>()
+    }
+
+    x.<!AMBIGUITY!>dec<!>()
+}
+
+// NB. it is the same function as `nullWhenNull`, but annotations specifies other facet of the function behaviour
+fun notNullWhenNotNull (x: Int?): Int? {
+    contract {
+        returns(null) implies (x == null)
+    }
+    return x?.inc()
+}
+
+fun testNotNullWhenNotNull (x: Int?) {
+    if (notNullWhenNotNull(x) == null) {
+        x == null
+    }
+    else {
+        x.<!AMBIGUITY!>dec<!>()
+    }
+
+    if (notNullWhenNotNull(x) != null) {
+        x.<!AMBIGUITY!>dec<!>()
+    }
+    else {
+        x == null
+    }
+
+    x.<!AMBIGUITY!>dec<!>()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperator.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperator.fir.kt
new file mode 100644
index 00000000000..c71e14966dd
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperator.fir.kt
@@ -0,0 +1,81 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun trueWhenString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun trueWhenInt(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is Int)
+    }
+    return x is Int
+}
+
+fun falseWhenString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun falseWhenInt(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is Int)
+    }
+    return x !is Int
+}
+
+
+// ==== Actual tests ====
+
+fun truetrue(x: Any?) {
+    if (trueWhenString(x) && trueWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+    x.<!AMBIGUITY!>inc<!>()
+}
+
+fun truefalse(x: Any?) {
+    if (trueWhenString(x) && falseWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun falsetrue(x: Any?) {
+    if (falseWhenString(x) && trueWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun falsefalse(x: Any?) {
+    if (falseWhenString(x) && falseWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        // Note that we can't argue that we have any of smartcasts here,
+        // because we don't know which one of both arguments was 'false' to bring us here
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperatorWithConstant.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperatorWithConstant.fir.kt
new file mode 100644
index 00000000000..6ef3ca6f18c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperatorWithConstant.fir.kt
@@ -0,0 +1,60 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun trueWhenString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun falseWhenString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+
+
+
+fun annotatedTrueAndTrue(x: Any?) {
+    if (trueWhenString(x) && true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedTrueAndFalse(x: Any?) {
+    if (trueWhenString(x) && false) {
+        // Unreachable
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalseAndTrue(x: Any?) {
+    if (falseWhenString(x) && true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalseAndFalse(x: Any?) {
+    if (falseWhenString(x) && false) {
+        // Unreachable
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperatorWithUnknown.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperatorWithUnknown.fir.kt
new file mode 100644
index 00000000000..79bd086d88b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/andOperatorWithUnknown.fir.kt
@@ -0,0 +1,60 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun trueWhenString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun falseWhenString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun unknownFunction(x: Any?) = x == 42
+
+
+
+
+fun annotatedTrue(x: Any?) {
+    if (trueWhenString(x) && unknownFunction(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalse(x: Any?) {
+    if (falseWhenString(x) && unknownFunction(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedTrueWithVariable(x: Any?, b: Boolean) {
+    if (trueWhenString(x) && b) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalseWithVariable(x: Any?, b: Boolean) {
+    if (falseWhenString(x) && b) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsOperator.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsOperator.fir.kt
new file mode 100644
index 00000000000..db2ed812e47
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsOperator.fir.kt
@@ -0,0 +1,47 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun myEqualsNull(x: Int?): Boolean {
+    contract {
+        returns(false) implies (x != null)
+    }
+    return x == null
+}
+
+fun myEqualsNotNull(x: Int?): Boolean {
+    contract {
+        returns(true) implies (x != null)
+    }
+    return x != null
+}
+
+fun testBasicEquals(x: Int?) {
+    x.<!AMBIGUITY!>inc<!>()
+
+    if (myEqualsNull(x)) {
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!AMBIGUITY!>inc<!>()
+    }
+
+    x.<!AMBIGUITY!>inc<!>()
+}
+
+fun testBasicNotEquals(x: Int?) {
+    x.<!AMBIGUITY!>inc<!>()
+
+    if (myEqualsNotNull(x)) {
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!AMBIGUITY!>inc<!>()
+    }
+
+    x.<!AMBIGUITY!>inc<!>()
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsWithNullableBoolean.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsWithNullableBoolean.fir.kt
new file mode 100644
index 00000000000..74db3f0de4e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsWithNullableBoolean.fir.kt
@@ -0,0 +1,69 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun safeIsString(x: Any?): Boolean? {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x?.let { it is String }
+}
+
+
+
+
+fun equalsTrue(x: Any?) {
+    if (safeIsString(x) == true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun equalsFalse(x: Any?) {
+    if (safeIsString(x) == false) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun equalsNull(x: Any?) {
+    if (safeIsString(x) == null) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun notEqualsTrue(x: Any?) {
+    if (safeIsString(x) != true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun notEqualsFalse(x: Any?) {
+    if (safeIsString(x) != false) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun notEqualsNull(x: Any?) {
+    if (safeIsString(x) != null) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/isInstanceOperator.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/isInstanceOperator.fir.kt
new file mode 100644
index 00000000000..87ca4fe3448
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/isInstanceOperator.fir.kt
@@ -0,0 +1,60 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+
+fun notIsString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+
+
+
+fun testSimple(x: Any?) {
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+
+    if (isString(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun testSpilling(x: Any?) {
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+
+    if (isString(x)) x.<!UNRESOLVED_REFERENCE!>length<!>
+
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testInversion(x: Any?) {
+    if (notIsString(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun testInversionSpilling(x: Any?) {
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+
+    if (notIsString(x)) else x.<!UNRESOLVED_REFERENCE!>length<!>
+
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperator.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperator.fir.kt
new file mode 100644
index 00000000000..2d34f9ab762
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperator.fir.kt
@@ -0,0 +1,78 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun trueWhenString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun trueWhenInt(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is Int)
+    }
+    return x is Int
+}
+
+fun falseWhenString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun falseWhenInt(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is Int)
+    }
+    return x !is Int
+}
+
+fun truetrue(x: Any?) {
+    if (trueWhenString(x) || trueWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun truefalse(x: Any?) {
+    if (trueWhenString(x) || falseWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun falsetrue(x: Any?) {
+    if (falseWhenString(x) || trueWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
+
+fun falsefalse(x: Any?) {
+    if (falseWhenString(x) || falseWhenInt(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        x.<!AMBIGUITY!>inc<!>()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperatorWithConstant.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperatorWithConstant.fir.kt
new file mode 100644
index 00000000000..d23f3ec6f34
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperatorWithConstant.fir.kt
@@ -0,0 +1,57 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun trueWhenString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun falseWhenString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun annotatedTrueOrTrue(x: Any?) {
+    if (trueWhenString(x) || true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        // Unreachable
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedTrueOrFalse(x: Any?) {
+    if (trueWhenString(x) || false) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalseOrTrue(x: Any?) {
+    if (falseWhenString(x) || true) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        // Unreachable
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalseOrFalse(x: Any?) {
+    if (falseWhenString(x) || false) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperatorWithUnknown.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperatorWithUnknown.fir.kt
new file mode 100644
index 00000000000..c923d79e88e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/orOperatorWithUnknown.fir.kt
@@ -0,0 +1,60 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun trueWhenString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun falseWhenString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun unknownFunction(x: Any?) = x == 42
+
+
+
+
+fun annotatedTrue(x: Any?) {
+    if (trueWhenString(x) || unknownFunction(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalse(x: Any?) {
+    if (falseWhenString(x) || unknownFunction(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedTrueWithVariable(x: Any?, b: Boolean) {
+    if (trueWhenString(x) || b) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun annotatedFalseWithVariable(x: Any?, b: Boolean) {
+    if (falseWhenString(x) || b) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/partiallyIncorrect.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/partiallyIncorrect.fir.kt
new file mode 100644
index 00000000000..5b0a30c506d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/partiallyIncorrect.fir.kt
@@ -0,0 +1,21 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun incorrectPartDoesntMatter(x: Any?) {
+    if (isString(x) && 1) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/receiver.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/receiver.fir.kt
new file mode 100644
index 00000000000..9d993cd451f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/receiver.fir.kt
@@ -0,0 +1,36 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+// !WITH_NEW_INFERENCE
+
+import kotlin.contracts.*
+
+fun Any?.isNull(): Boolean {
+    contract {
+        returns(false) implies (this@isNull != null)
+    }
+    return this == null
+}
+
+fun smartcastOnReceiver(x: Int?) {
+    if (x.isNull()) {
+        x.<!AMBIGUITY!>inc<!>()
+    }
+    else {
+        x.<!AMBIGUITY!>dec<!>()
+    }
+}
+
+class UnstableReceiver {
+    var x: Int? = 42
+
+    fun smartcastOnUnstableReceiver() {
+        if (x.isNull()) {
+            x.<!AMBIGUITY!>inc<!>()
+        }
+        else {
+            x.<!AMBIGUITY!>dec<!>()
+        }
+    }
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/safecallAndReturnsNull.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/safecallAndReturnsNull.fir.kt
new file mode 100644
index 00000000000..96916e514e9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/safecallAndReturnsNull.fir.kt
@@ -0,0 +1,17 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+
+import kotlin.contracts.*
+
+fun Any.nullWhenString(): Any? {
+    contract {
+        returns(null) implies (this@nullWhenString is String)
+    }
+    return if (this is String) null else this
+}
+
+fun test(x: Int?) {
+    if (x?.nullWhenString() == null) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/throwsEffect.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/throwsEffect.fir.kt
new file mode 100644
index 00000000000..9a045826426
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/throwsEffect.fir.kt
@@ -0,0 +1,66 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun myAssert(condition: Boolean) {
+    contract {
+        returns() implies (condition)
+    }
+    if (!condition) throw kotlin.<!UNRESOLVED_REFERENCE!>IllegalArgumentException<!>("Assertion failed")
+}
+
+fun testAssertSmartcast(x: Any?) {
+    myAssert(x is String)
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testInvertedAssert(x: Any?) {
+    myAssert(x !is String)
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testSpilling(x: Any?) {
+    if (x != null) {
+        myAssert(x is String)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testAssertInIf(x: Any?) {
+    if (myAssert(x is String) == Unit) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun testTryCatch(x: Any?) {
+    try {
+        myAssert(x is String)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    } catch (e: kotlin.IllegalArgumentException) {
+
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testUncertainFlow(x: Any?) {
+    repeat(x.toString().length) {
+        myAssert(x is String)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun testAtLeastOnceFlow(x: Any?) {
+    do {
+        myAssert(x is String)
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    } while (x != null)
+
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/typeSmartcastWhenNullability.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/typeSmartcastWhenNullability.fir.kt
new file mode 100644
index 00000000000..5c032d8b228
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/typeSmartcastWhenNullability.fir.kt
@@ -0,0 +1,59 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+
+fun nullWhenString(x: Any?): Int? {
+    contract {
+        returns(null) implies (x is String)
+    }
+    return if (x is String) null else 42
+}
+
+fun nullWhenNotString(x: Any?): Int? {
+    contract {
+        returns(null) implies (x !is String)
+    }
+    return if (x !is String) null else 42
+}
+
+
+
+
+
+// ==== Actual tests =====
+
+
+fun test1(x: Any?) {
+    // condition == true <=> function returned null <=> 'x' is String
+    if (nullWhenString(x) == null) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun test2(x: Any?) {
+    // Observe that condition == false <=>* function returned null <=> 'x' is String
+    // *correct only for at most binary types, which is exactly the case for nullability comparisons
+    if (nullWhenString(x) != null) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+
+fun test3(x: Any?) {
+    // condition == false <=> function returned not-null, but we don't know anything about when function returns not-null
+    if (nullWhenNotString(x) == null) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/unreachableBranches.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/unreachableBranches.fir.kt
new file mode 100644
index 00000000000..12cf3f1112b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/unreachableBranches.fir.kt
@@ -0,0 +1,32 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+// ===== Definitions ====
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+
+// ==== Actual tests =======
+
+fun implicitAlwaysFalse(x: Any?) {
+    if (isString(x) && !isString(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun implicitAlwaysFalseSpilling(x: Any?) {
+    if (isString(x) && !isString(x)) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/valueOfContractedFunctionIngored.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/valueOfContractedFunctionIngored.fir.kt
new file mode 100644
index 00000000000..00937d84442
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/valueOfContractedFunctionIngored.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun f3(value: String?) {
+    if (!value.isNullOrEmpty() is Boolean) {
+        value.<!INAPPLICABLE_CANDIDATE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubject.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubject.fir.kt
new file mode 100644
index 00000000000..0315f2c2357
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubject.fir.kt
@@ -0,0 +1,36 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun exhaustive(x: Any?) {
+    when (isString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when(!isString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun smartcastInElse(x: Any?) {
+    when (isString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (!isString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubjectNullableBoolean.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubjectNullableBoolean.fir.kt
new file mode 100644
index 00000000000..c0e3058acae
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubjectNullableBoolean.fir.kt
@@ -0,0 +1,56 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun safeIsString(x: Any?): Boolean? {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x?.let { it is String }
+}
+
+fun elseWithNullableResult(x: Any?) {
+    when (safeIsString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun exhaustiveWithNullableResult(x: Any?) {
+    when (safeIsString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withoutSubject.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withoutSubject.fir.kt
new file mode 100644
index 00000000000..aea3e2db6da
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withoutSubject.fir.kt
@@ -0,0 +1,31 @@
+// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun exhaustive(x: Any?) {
+    when {
+        isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        !isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when {
+        !isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun smartcastInElse(x: Any?) {
+    when {
+        !isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/deprecated/deprecationOnReadBytes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/deprecated/deprecationOnReadBytes.fir.kt
new file mode 100644
index 00000000000..f00e93f243d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/deprecated/deprecationOnReadBytes.fir.kt
@@ -0,0 +1,7 @@
+import java.io.InputStream
+
+fun InputStream.test() {
+    readBytes()
+
+    readBytes(1)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/deprecated/noDeprecationOnReadBytes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/deprecated/noDeprecationOnReadBytes.fir.kt
new file mode 100644
index 00000000000..df951011425
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/deprecated/noDeprecationOnReadBytes.fir.kt
@@ -0,0 +1,9 @@
+// !API_VERSION: 1.2
+
+import java.io.InputStream
+
+fun InputStream.test() {
+    readBytes()
+
+    readBytes(1)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/delegatedProperty.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/delegatedProperty.fir.kt
new file mode 100644
index 00000000000..2af8869417b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/delegatedProperty.fir.kt
@@ -0,0 +1,7 @@
+import kotlin.properties.ReadWriteProperty
+import kotlin.properties.Delegates
+
+class C {
+    val `x$delegate`: ReadWriteProperty<Any, Any>? = null
+    val x: String? by Delegates.notNull()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmNames.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmNames.fir.kt
new file mode 100644
index 00000000000..6add6273f2c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmNames.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@JvmName("bar")
+fun foo(a: Any) {}
+
+fun Any.foo() {}
+
+@JvmName("barInt")
+fun bar(x: List<Int>) {}
+
+@JvmName("barStr")
+fun bar(x: List<String>) {}
+
+class C {
+    var rwProp: Int
+        @JvmName("get_rwProp")
+        get() = 0
+        @JvmName("set_rwProp")
+        set(v) {}
+
+    fun getRwProp(): Int = 123
+    fun setRwProp(v: Int) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmNamesDuplicate.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmNamesDuplicate.fir.kt
new file mode 100644
index 00000000000..10d82927fd3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmNamesDuplicate.fir.kt
@@ -0,0 +1,53 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+@JvmName("bar")
+fun foo(a: Any) {}
+
+fun bar(a: Any) {}
+
+class C {
+    @JvmName("foo1")
+    fun foo(list: List<Int>) {}
+
+    @JvmName("foo1")
+    fun foo(list: List<String>) {}
+}
+
+// Conflicts in inheritance.
+
+// A1 -> B1 with accidental override
+
+open class A1 {
+    @JvmName("bar")
+    open fun foo() {}
+}
+
+class B1 : A1() {
+    fun bar() {}
+}
+
+// A2 -> B2 with intended override and conflicting JVM declarations
+
+open class A2 {
+    @JvmName("bar")
+    open fun foo() {}
+}
+
+class B2 : A2() {
+    override fun foo() {}
+
+    fun bar() {}
+}
+
+// A3 -> B3 -> C3 with accidental override
+
+open class A3 {
+    @JvmName("bar")
+    open fun foo() {}
+}
+
+open class B3: A3() {
+}
+
+class C3: B3() {
+    fun bar() {}
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmOverloads.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmOverloads.fir.kt
new file mode 100644
index 00000000000..a394011a653
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmOverloads.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+class A {
+    @kotlin.jvm.JvmOverloads fun foo(s: String = "") {
+    }
+
+    fun foo() {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmStaticInClassObject.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmStaticInClassObject.fir.kt
new file mode 100644
index 00000000000..75dbf07a49b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmStaticInClassObject.fir.kt
@@ -0,0 +1,9 @@
+open class Base {
+    fun foo() {}
+}
+
+class Derived : Base() {
+    companion object {
+        @JvmStatic fun foo() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmStaticInObject.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmStaticInObject.fir.kt
new file mode 100644
index 00000000000..4d62b986a12
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/jvmStaticInObject.fir.kt
@@ -0,0 +1,8 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+open class Base {
+    fun `foo$default`(i: Int, mask: Int, mh: Any) {}
+}
+
+object Derived : Base() {
+    @JvmStatic fun foo(i: Int = 0) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jjk.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jjk.fir.kt
new file mode 100644
index 00000000000..15daf06a85c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jjk.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A {
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: B.java
+
+public class B extends A {
+    public static void bar(int i) {}
+}
+
+// FILE: K.kt
+
+open class K : B() {
+    companion object {
+        @JvmStatic
+        fun foo() {}
+        @JvmStatic
+        fun foo(a: Any) {}
+        @JvmStatic
+        fun bar(i: Int) {}
+        @JvmStatic
+        fun bar(i: String) {}
+        @JvmStatic
+        fun baz(i: Int) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jk.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jk.fir.kt
new file mode 100644
index 00000000000..afa092473d0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jk.fir.kt
@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A {
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: K.kt
+
+open class K : A() {
+    companion object {
+        @JvmStatic
+        fun foo() {}
+        @JvmStatic
+        fun foo(i: Int) {}
+        @JvmStatic
+        fun baz(i: Int) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jkjk.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jkjk.fir.kt
new file mode 100644
index 00000000000..4cbfbe6900e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/jkjk.fir.kt
@@ -0,0 +1,36 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: A.java
+
+public class A {
+    public static void foo() {}
+    public static void baz(String s) {}
+}
+
+// FILE: B.kt
+
+open class B : A() {
+}
+
+// FILE: C.java
+
+public class C extends B {
+    public static void bar(int i) {}
+}
+
+// FILE: K.kt
+
+open class K : C() {
+    companion object {
+        @JvmStatic
+        fun foo() {}
+        @JvmStatic
+        fun foo(a: Any) {}
+        @JvmStatic
+        fun bar(i: Int) {}
+        @JvmStatic
+        fun bar(i: String) {}
+        @JvmStatic
+        fun baz(i: Int) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/kotlinMembersVsJavaNonVisibleStatics.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/kotlinMembersVsJavaNonVisibleStatics.fir.kt
new file mode 100644
index 00000000000..8b4d5883db4
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/duplicateJvmSignature/statics/kotlinMembersVsJavaNonVisibleStatics.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+// FILE: foo/A.java
+
+package foo;
+
+public class A {
+    private static void foo(int s) {}
+    static void bar(double s) {}
+}
+
+// FILE: K.kt
+import foo.A
+
+open class K : A() {
+    companion object {
+        @JvmStatic
+        fun foo(i: Int) {}
+        @JvmStatic
+        fun bar(d: Double) {}
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/elvisOnJavaList.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/elvisOnJavaList.fir.kt
new file mode 100644
index 00000000000..9c95f9f8929
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/elvisOnJavaList.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+
+// FILE: P.java
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class P {
+    public List<Integer> getList() {
+        return new ArrayList<Integer>();
+    }
+}
+
+// FILE: Test.kt
+
+fun foo(c: P): MutableList<Int> {
+    // Error should be here: see KT-8168 Typechecker fails for platform collection type
+    return c.getList() ?: listOf()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/elvisOnUnitInLet.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/elvisOnUnitInLet.fir.kt
new file mode 100644
index 00000000000..a4e9d5b483f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/elvisOnUnitInLet.fir.kt
@@ -0,0 +1,9 @@
+fun foo(x: Int?) {
+    // Both parts of the Elvis should be alive, see KT-7936
+    x?.let {
+        smth()
+    }?: orElse()
+}
+
+fun smth() {}
+fun orElse() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/annotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/annotation.fir.kt
new file mode 100644
index 00000000000..031c167292b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/annotation.fir.kt
@@ -0,0 +1,136 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY, AnnotationTarget.TYPEALIAS,
+        AnnotationTarget.VALUE_PARAMETER)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+@Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY, AnnotationTarget.TYPEALIAS,
+        AnnotationTarget.VALUE_PARAMETER)
+annotation class EAnno
+
+// FILE: usage-propagate.kt
+
+package usage1
+
+import api.*
+
+@ExperimentalAPI
+@EAnno fun function() {}
+
+@ExperimentalAPI
+fun parameter(@EAnno p: String) {}
+
+@ExperimentalAPI
+fun parameterType(p: @EAnno String) {}
+
+@ExperimentalAPI
+fun returnType(): @EAnno Unit {}
+
+@ExperimentalAPI
+@EAnno val property = ""
+
+@ExperimentalAPI
+@EAnno typealias Typealias = Unit
+
+@ExperimentalAPI
+@EAnno class Klass
+
+@ExperimentalAPI
+annotation class AnnotationArgument(val p: EAnno)
+
+@ExperimentalAPI
+fun insideBody() {
+    @EAnno fun local() {}
+}
+
+@ExperimentalAPI
+fun inDefaultArgument(f: () -> Unit = @EAnno fun() {}) {}
+
+@ExperimentalAPI
+val inProperty = @EAnno fun() {}
+
+@ExperimentalAPI
+val inPropertyAccessor: () -> Unit
+    get() = @EAnno fun() {}
+
+// FILE: usage-use.kt
+
+package usage2
+
+import api.*
+
+@UseExperimental(ExperimentalAPI::class)
+@EAnno fun function() {}
+
+@UseExperimental(ExperimentalAPI::class)
+fun parameter(@EAnno p: String) {}
+
+@UseExperimental(ExperimentalAPI::class)
+fun parameterType(p: @EAnno String) {}
+
+@UseExperimental(ExperimentalAPI::class)
+fun returnType(): @EAnno Unit {}
+
+@UseExperimental(ExperimentalAPI::class)
+@EAnno val property = ""
+
+@UseExperimental(ExperimentalAPI::class)
+@EAnno typealias Typealias = Unit
+
+@UseExperimental(ExperimentalAPI::class)
+@EAnno class Klass
+
+@UseExperimental(ExperimentalAPI::class)
+annotation class AnnotationArgument(val p: EAnno)
+
+fun insideBody() {
+    @UseExperimental(ExperimentalAPI::class) @EAnno fun local() {}
+}
+
+fun inDefaultArgument(@UseExperimental(ExperimentalAPI::class) f: () -> Unit = @EAnno fun() {}) {}
+
+@UseExperimental(ExperimentalAPI::class)
+val inProperty = @EAnno fun() {}
+
+val inPropertyAccessor: () -> Unit
+    @UseExperimental(ExperimentalAPI::class)
+    get() = @EAnno fun() {}
+
+// FILE: usage-none.kt
+
+package usage3
+
+import api.*
+
+@EAnno fun function() {}
+
+fun parameter(@EAnno p: String) {}
+
+fun parameterType(p: @EAnno String) {}
+
+fun returnType(): @EAnno Unit {}
+
+@EAnno val property = ""
+
+@EAnno typealias Typealias = Unit
+
+@EAnno class Klass
+
+annotation class AnnotationArgument(val p: EAnno)
+
+fun insideBody() {
+    @EAnno fun local() {}
+}
+
+fun inDefaultArgument(f: () -> Unit = @EAnno fun() {}) {}
+
+val inProperty = @EAnno fun() {}
+
+val inPropertyAccessor: () -> Unit
+    get() = @EAnno fun() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsages.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsages.fir.kt
new file mode 100644
index 00000000000..0e2663bf6bd
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsages.fir.kt
@@ -0,0 +1,30 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+annotation class ExperimentalAPI
+
+interface I
+
+@ExperimentalAPI
+class Impl : I
+
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+open class Base(val i: I)
+
+@UseExperimental(ExperimentalAPI::class)
+class Derived : Base(Impl())
+
+@UseExperimental(ExperimentalAPI::class)
+class Delegated : I by Impl()
+
+@UseExperimental(ExperimentalAPI::class)
+val delegatedProperty by Impl()
+operator fun I.getValue(x: Any?, y: Any?) = null
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsagesAndInline.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsagesAndInline.fir.kt
new file mode 100644
index 00000000000..d9629d2f927
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/bodyUsagesAndInline.fir.kt
@@ -0,0 +1,83 @@
+// !DIAGNOSTICS: -NOTHING_TO_INLINE -UNUSED_PARAMETER
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+annotation class API
+
+@API
+fun f() {}
+
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+fun use1() {
+    f()
+}
+
+val use2 = f()
+
+// FILE: inline-usage.kt
+
+package usage
+
+import api.*
+
+inline fun inlineUse1() {
+    f()
+}
+
+inline var inlineUse2: Unit
+    get() {
+        f()
+    }
+    set(value) {
+        f()
+    }
+
+var inlineUse3: Unit
+    inline get() {
+        f()
+    }
+    @API
+    inline set(value) {
+        f()
+    }
+
+@API
+inline fun inlineUse4() {
+    f()
+}
+
+// FILE: private-inline-usage.kt
+
+package usage
+
+import api.*
+
+private inline fun privateInline1() {
+    f()
+}
+
+internal inline fun privateInline2() {
+    f()
+}
+
+private inline var privateInline3: Unit
+    get() {
+        f()
+    }
+    set(value) {
+        f()
+    }
+
+internal class InternalClass {
+    inline fun privateInline4() {
+        f()
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/classMembers.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/classMembers.fir.kt
new file mode 100644
index 00000000000..0c8699c638b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/classMembers.fir.kt
@@ -0,0 +1,88 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+class C {
+    fun function(): String = ""
+    val property: String = ""
+    class Nested
+    inner class Inner
+}
+
+@ExperimentalAPI
+fun C.extension() {}
+
+// FILE: usage-propagate.kt
+
+package usage1
+
+import api.*
+
+@ExperimentalAPI
+fun useAll() {
+    val c: C = C()
+    c.function()
+    c.property
+    C.Nested()
+    c.Inner()
+    c.extension()
+}
+
+@ExperimentalAPI
+class Use {
+    fun useAll(c: C) {
+        c.function()
+        c.property
+        C.Nested()
+        c.Inner()
+        c.extension()
+    }
+}
+
+// FILE: usage-use.kt
+
+package usage2
+
+import api.*
+
+@UseExperimental(ExperimentalAPI::class)
+fun useAll() {
+    val c: C = C()
+    c.function()
+    c.property
+    C.Nested()
+    c.Inner()
+    c.extension()
+}
+
+@UseExperimental(ExperimentalAPI::class)
+class Use {
+    fun useAll(c: C) {
+        c.function()
+        c.property
+        C.Nested()
+        c.Inner()
+        c.extension()
+    }
+}
+
+// FILE: usage-none.kt
+
+package usage3
+
+import api.*
+
+fun use() {
+    val c: C = C()
+    c.function()
+    c.property
+    C.Nested()
+    c.Inner()
+    c.extension()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/classMembersOverlyExperimental.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/classMembersOverlyExperimental.fir.kt
new file mode 100644
index 00000000000..ca6192f1c87
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/classMembersOverlyExperimental.fir.kt
@@ -0,0 +1,36 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+class C {
+    @ExperimentalAPI
+    fun function() {}
+
+    @ExperimentalAPI
+    val property: String = ""
+
+    @ExperimentalAPI
+    class Nested {
+        @ExperimentalAPI
+        fun nestedFunction() {}
+    }
+}
+
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+fun use() {
+    val c: C = C()
+    c.function()
+    c.property
+    C.Nested().nestedFunction()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/constVal.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/constVal.fir.kt
new file mode 100644
index 00000000000..229705b4db8
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/constVal.fir.kt
@@ -0,0 +1,43 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.PROPERTY, AnnotationTarget.FUNCTION)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+const val MEANING = 42
+
+annotation class Anno(val value: Int)
+
+// FILE: usage-propagate.kt
+
+package usage1
+
+import api.*
+
+@ExperimentalAPI
+@Anno(MEANING)
+fun usage() {}
+
+// FILE: usage-use.kt
+
+@file:UseExperimental(ExperimentalAPI::class)
+package usage2
+
+import api.*
+
+// TODO: there should be no warning here
+@Anno(MEANING)
+fun usage() {}
+
+// FILE: usage-none.kt
+
+package usage3
+
+import api.*
+
+@Anno(MEANING)
+fun usage() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/deeplyNestedClass.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/deeplyNestedClass.fir.kt
new file mode 100644
index 00000000000..518fe17fea4
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/deeplyNestedClass.fir.kt
@@ -0,0 +1,57 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+class C {
+    class D {
+        class E {
+            class F
+        }
+    }
+}
+
+// FILE: usage-propagate.kt
+
+package usage1
+
+import api.*
+
+@ExperimentalAPI
+fun use1() {
+    C.D.E.F()
+}
+
+@ExperimentalAPI
+fun use2(f: C.D.E.F) = f.hashCode()
+
+// FILE: usage-use.kt
+
+package usage2
+
+import api.*
+
+@UseExperimental(ExperimentalAPI::class)
+fun use1() {
+    C.D.E.F()
+}
+
+@UseExperimental(ExperimentalAPI::class)
+fun use2(f: C.D.E.F) = f.hashCode()
+
+// FILE: usage-none.kt
+
+package usage3
+
+import api.*
+
+fun use1() {
+    C.D.E.F()
+}
+
+fun use2(f: C.D.E.F) = f.hashCode()
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/errors.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/errors.fir.kt
new file mode 100644
index 00000000000..1152354a790
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/errors.fir.kt
@@ -0,0 +1,26 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental
+annotation class E
+
+open class Base {
+    @E
+    open fun foo() {}
+}
+
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+class Derived : Base() {
+    override fun foo() {}
+}
+
+fun test(b: Base) {
+    b.foo()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalIsNotEnabled.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalIsNotEnabled.fir.kt
new file mode 100644
index 00000000000..4c9a92f8f84
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalIsNotEnabled.fir.kt
@@ -0,0 +1,23 @@
+// FILE: api.kt
+
+@Experimental
+annotation class Marker
+
+@Marker
+fun f() {}
+
+// FILE: usage.kt
+
+fun use1() {
+    f()
+}
+
+@Marker
+fun use2() {
+    f()
+}
+
+@UseExperimental(Marker::class)
+fun use3() {
+    f()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnWholeModule.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnWholeModule.fir.kt
new file mode 100644
index 00000000000..b05884b7a67
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalOnWholeModule.fir.kt
@@ -0,0 +1,23 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !EXPERIMENTAL: api.ExperimentalAPI
+// MODULE: api
+// FILE: api.kt
+
+package api
+
+@Experimental
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+fun function(): String = ""
+
+// MODULE: usage(api)
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+fun use() {
+    function()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalUnsignedLiterals.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalUnsignedLiterals.fir.kt
new file mode 100644
index 00000000000..2542462f639
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/experimentalUnsignedLiterals.fir.kt
@@ -0,0 +1,33 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !DIAGNOSTICS: -UNUSED_EXPRESSION, -UNUSED_VARIABLE, -UNUSED_PARAMETER
+
+fun test() {
+    42u
+    21UL
+    val list = listOf(
+        1u,
+        0xFFu,
+        0xbbU
+    )
+
+    <!INAPPLICABLE_CANDIDATE!>takeAll<!>(
+        1u,
+        2u,
+        3u,
+        4u,
+        5u
+    )
+
+    @UseExperimental(ExperimentalUnsignedTypes::class) 42u
+}
+
+fun takeAll(
+    b: UByte,
+    s: UShort,
+    i: UInt,
+    l: ULong,
+    vararg uints: UInt
+) {}
+
+const val unsignedConst = 0u
+const val unsignedLongConst = 0uL
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/fullFqNameUsage.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/fullFqNameUsage.fir.kt
new file mode 100644
index 00000000000..f3ef9111d2c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/fullFqNameUsage.fir.kt
@@ -0,0 +1,12 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+
+package test.abc
+
+@Experimental
+annotation class E
+
+@UseExperimental(test.abc.E::class)
+fun f() {}
+
+@test.abc.E
+fun g() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/importStatement.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/importStatement.fir.kt
new file mode 100644
index 00000000000..724647e4367
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/importStatement.fir.kt
@@ -0,0 +1,27 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package feature.experimental.self
+
+@Experimental
+annotation class ImportedMarker
+
+@ImportedMarker
+object ImportedClass {
+    @ImportedMarker
+    fun importedObjectMember() {}
+}
+
+@ImportedMarker
+fun importedFunction() {}
+
+@ImportedMarker
+val importedProperty = Unit
+
+// FILE: usage.kt
+
+import feature.experimental.self.ImportedMarker
+import feature.experimental.self.ImportedClass
+import feature.experimental.self.importedFunction
+import feature.experimental.self.importedProperty
+import feature.experimental.self.ImportedClass.importedObjectMember
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectTargetsForExperimentalAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectTargetsForExperimentalAnnotation.fir.kt
new file mode 100644
index 00000000000..72719d13e86
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectTargetsForExperimentalAnnotation.fir.kt
@@ -0,0 +1,25 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+import kotlin.annotation.AnnotationTarget.*
+
+@Experimental(Experimental.Level.WARNING)
+@Target(CLASS, ANNOTATION_CLASS, TYPE_PARAMETER, PROPERTY, FIELD, LOCAL_VARIABLE, VALUE_PARAMETER, CONSTRUCTOR, FUNCTION,
+        PROPERTY_GETTER, PROPERTY_SETTER, TYPE, TYPEALIAS)
+annotation class E1
+
+@Experimental(Experimental.Level.WARNING)
+@Target(FILE)
+annotation class E2
+
+@Experimental(Experimental.Level.WARNING)
+@Target(EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class E3
+
+@Experimental(Experimental.Level.WARNING)
+@Target(FILE, EXPRESSION)
+@Retention(AnnotationRetention.SOURCE)
+annotation class E4
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectUseExperimental.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectUseExperimental.fir.kt
new file mode 100644
index 00000000000..afe947cad08
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/incorrectUseExperimental.fir.kt
@@ -0,0 +1,9 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+
+annotation class NotAMarker
+
+@UseExperimental
+fun f1() {}
+
+@UseExperimental(NotAMarker::class)
+fun f2() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/override.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/override.fir.kt
new file mode 100644
index 00000000000..5af4512d79f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/override.fir.kt
@@ -0,0 +1,44 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+annotation class E
+
+open class Base {
+    @E
+    open fun foo() {}
+}
+
+class DerivedInSameModule : Base() {
+    override fun foo() {}
+}
+
+// FILE: usage-propagate.kt
+
+package usage1
+
+import api.*
+
+open class Derived : Base() {
+    @E
+    override fun foo() {}
+}
+
+class SubDerived : Derived()
+
+@E
+class Derived2 : Base() {
+    override fun foo() {}
+}
+
+// FILE: usage-none.kt
+
+package usage2
+
+import api.*
+
+class Derived : Base() {
+    override fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/overrideDifferentExperimentalities.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/overrideDifferentExperimentalities.fir.kt
new file mode 100644
index 00000000000..a0702b4b150
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/overrideDifferentExperimentalities.fir.kt
@@ -0,0 +1,35 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+
+@Experimental(Experimental.Level.WARNING)
+annotation class E1
+@Experimental(Experimental.Level.WARNING)
+annotation class E3
+
+interface Base1 {
+    @E1
+    fun foo()
+}
+
+interface Base2 {
+    fun foo()
+}
+
+interface Base3 {
+    @E3
+    fun foo()
+}
+
+class DerivedA : Base1, Base2, Base3 {
+    override fun foo() {}
+}
+
+class DerivedB : Base1, Base3 {
+    @E3
+    override fun foo() {}
+}
+
+class DerivedC : Base1, Base2, Base3 {
+    @E1
+    @E3
+    override fun foo() {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/topLevel.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/topLevel.fir.kt
new file mode 100644
index 00000000000..71779d83afa
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/topLevel.fir.kt
@@ -0,0 +1,78 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.TYPE, AnnotationTarget.CLASS, AnnotationTarget.FUNCTION, AnnotationTarget.PROPERTY, AnnotationTarget.TYPEALIAS,
+        AnnotationTarget.VALUE_PARAMETER)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+fun function(): String = ""
+
+@ExperimentalAPI
+val property: String = ""
+
+@ExperimentalAPI
+typealias Typealias = String
+
+// FILE: usage-propagate.kt
+
+package usage1
+
+import api.*
+
+@ExperimentalAPI
+fun useAll() {
+    function()
+    property
+    val s: Typealias = ""
+}
+
+@ExperimentalAPI
+class Use {
+    fun useAll() {
+        function()
+        property
+        val s: Typealias = ""
+    }
+}
+
+// FILE: usage-use.kt
+
+package usage2
+
+import api.*
+
+fun useAll() {
+    @UseExperimental(ExperimentalAPI::class)
+    <!UNRESOLVED_REFERENCE!>{
+        function()
+        property
+        val s: Typealias = ""
+    }()<!>
+}
+
+@UseExperimental(ExperimentalAPI::class)
+class Use {
+    fun useAll() {
+        function()
+        property
+        val s: Typealias = ""
+    }
+}
+
+// FILE: usage-none.kt
+
+package usage3
+
+import api.*
+
+fun use() {
+    function()
+    property
+    val s: Typealias = ""
+    s.hashCode()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/typealias.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/typealias.fir.kt
new file mode 100644
index 00000000000..b101b799956
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/typealias.fir.kt
@@ -0,0 +1,13 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental
+@Target(AnnotationTarget.CLASS)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+class Foo
+
+typealias Bar = Foo
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/usageNotAsAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/usageNotAsAnnotation.fir.kt
new file mode 100644
index 00000000000..fd4db89d150
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/usageNotAsAnnotation.fir.kt
@@ -0,0 +1,77 @@
+// !LANGUAGE: +NestedClassesInAnnotations
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: api.kt
+
+package test
+
+import kotlin.reflect.KClass
+
+// Usages in import should be OK
+import kotlin.Experimental.Level.*
+import kotlin.Experimental.Level
+import kotlin.Experimental
+
+// Usages with FQ names should be OK
+
+@kotlin.Experimental(kotlin.Experimental.Level.ERROR)
+annotation class M
+
+
+// Usages as types should be errors
+
+fun f1(e: Experimental) {}
+fun f2(u: UseExperimental?) {}
+
+typealias Experimental0 = Experimental
+typealias UseExperimental0 = UseExperimental
+fun f3(e: Experimental0 /* TODO */) {}
+fun f4(u: UseExperimental0 /* TODO */) {}
+
+
+// Usages as ::class literals should be errors
+
+annotation class VarargKClasses(vararg val k: KClass<*>)
+
+@VarargKClasses(
+    Experimental::class,
+    UseExperimental::class,
+    kotlin.Experimental::class,
+    kotlin.UseExperimental::class
+)
+fun f5() {}
+
+
+// Usages of markers as types should be errors
+
+@Experimental
+annotation class Marker {
+    class NestedClass
+
+    companion object {
+        const val value = 42
+    }
+}
+
+fun f6(m: Marker) {}
+fun f7(): List<Marker>? = null
+fun f8(): test.Marker? = null
+
+typealias Marker0 = Marker
+
+fun f9(m: Marker0) {}
+
+
+// Usages of markers as qualifiers are errors as well (we can lift this restriction for select cases)
+
+fun f10(m: Marker.NestedClass) {
+    Marker.value
+}
+
+// FILE: usage-from-other-file.kt
+
+// Usages of markers in import statements should be OK, but not as qualifiers to import their nested classes
+
+import test.Marker
+import test.Marker.NestedClass
+import test.Marker.Companion
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnFile.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnFile.fir.kt
new file mode 100644
index 00000000000..4eade3474ec
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnFile.fir.kt
@@ -0,0 +1,37 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.FUNCTION)
+annotation class ExperimentalAPI1
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.FUNCTION)
+annotation class ExperimentalAPI2
+
+@ExperimentalAPI1
+fun compilation() {}
+
+@ExperimentalAPI2
+fun runtime() {}
+
+// FILE: usage.kt
+
+@file:UseExperimental(ExperimentalAPI1::class)
+package usage
+
+import api.*
+
+fun use() {
+    compilation()
+    runtime()
+}
+
+class Use {
+    fun use() {
+        compilation()
+        runtime()
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnFileWithVeryExperimentalMarker.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnFileWithVeryExperimentalMarker.fir.kt
new file mode 100644
index 00000000000..02dea53ad33
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnFileWithVeryExperimentalMarker.fir.kt
@@ -0,0 +1,30 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+@Experimental(Experimental.Level.WARNING)
+annotation class VeryExperimentalAPI
+
+@ExperimentalAPI
+@VeryExperimentalAPI
+fun f() {}
+
+@ExperimentalAPI
+fun g() {}
+
+// FILE: usage.kt
+
+@file:UseExperimental(ExperimentalAPI::class, VeryExperimentalAPI::class)
+package usage
+
+import api.*
+
+fun usage() {
+    f()
+    g()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnWholeModule.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnWholeModule.fir.kt
new file mode 100644
index 00000000000..ceef76351ea
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalOnWholeModule.fir.kt
@@ -0,0 +1,22 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental api.ExperimentalAPI
+// MODULE: api
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.ERROR)
+annotation class ExperimentalAPI
+
+@ExperimentalAPI
+fun function(): String = ""
+
+// MODULE: usage(api)
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+fun use() {
+    function()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalTargets.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalTargets.fir.kt
new file mode 100644
index 00000000000..ca8d9b387c9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalTargets.fir.kt
@@ -0,0 +1,57 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.CLASS)
+annotation class E
+
+@E
+open class Foo(val s: String = "")
+
+// FILE: usage.kt
+
+import api.*
+
+@UseExperimental(E::class)
+class Klass {
+    init {
+        Foo()
+    }
+}
+
+class Constructor {
+    @UseExperimental(E::class) constructor() {
+        Foo()
+    }
+}
+
+@UseExperimental(E::class)
+val property = Foo().s
+
+@UseExperimental(E::class)
+fun function() {
+    Foo()
+}
+
+fun valueParameter(@UseExperimental(E::class) p: String = Foo().s): String {
+    @UseExperimental(E::class)
+    val localVariable: String = Foo().s
+    return localVariable
+}
+
+var propertyAccessors: String
+    @UseExperimental(E::class)
+    get() = Foo().s
+    @UseExperimental(E::class)
+    set(value) { Foo() }
+
+fun expression(): String {
+    val s = @UseExperimental(E::class) Foo().s
+    return s
+}
+
+@UseExperimental(E::class)
+typealias TypeAlias = Foo
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalWithSeveralAnnotations.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalWithSeveralAnnotations.fir.kt
new file mode 100644
index 00000000000..6a86758cd63
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/useExperimentalWithSeveralAnnotations.fir.kt
@@ -0,0 +1,52 @@
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// FILE: api.kt
+
+package api
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.FUNCTION)
+annotation class E1
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.FUNCTION)
+annotation class E2
+
+@Experimental(Experimental.Level.WARNING)
+@Target(AnnotationTarget.FUNCTION)
+annotation class E3
+
+@E1
+fun e1() {}
+
+@E2
+fun e2() {}
+
+@E3
+fun e3() {}
+
+// FILE: usage.kt
+
+package usage
+
+import api.*
+
+@UseExperimental(E1::class, E2::class, E3::class)
+fun use1() {
+    e1()
+    e2()
+    e3()
+}
+
+@UseExperimental(E1::class, E3::class)
+fun use2() {
+    e1()
+    @UseExperimental(E2::class) e2()
+    e3()
+}
+
+@UseExperimental(E1::class, E2::class)
+fun use3() {
+    e1()
+    e2()
+    e3()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.fir.kt
new file mode 100644
index 00000000000..258ab24a5e5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/experimental/wasExperimental.fir.kt
@@ -0,0 +1,59 @@
+// !API_VERSION: 1.2
+// !USE_EXPERIMENTAL: kotlin.Experimental
+// !DIAGNOSTICS: -INVISIBLE_MEMBER -INVISIBLE_REFERENCE -NEWER_VERSION_IN_SINCE_KOTLIN -UNUSED_PARAMETER
+
+@SinceKotlin("1.3")
+fun newPublishedFun() {}
+
+
+@Experimental
+annotation class Marker
+
+@SinceKotlin("1.3")
+@WasExperimental(Marker::class)
+fun newFunExperimentalInThePast() {}
+
+@SinceKotlin("1.3")
+@WasExperimental(Marker::class)
+val newValExperimentalInThePast = ""
+
+@SinceKotlin("1.3")
+@WasExperimental(Marker::class)
+class NewClassExperimentalInThePast
+
+@SinceKotlin("1.3")
+@WasExperimental(Marker::class)
+typealias TypeAliasToNewClass = NewClassExperimentalInThePast
+
+
+fun use1(
+    c1: NewClassExperimentalInThePast,
+    t1: TypeAliasToNewClass
+) {
+    newPublishedFun()
+    newFunExperimentalInThePast()
+    newValExperimentalInThePast
+    NewClassExperimentalInThePast()
+}
+
+@UseExperimental(Marker::class)
+fun use2(
+    c2: NewClassExperimentalInThePast,
+    t2: TypeAliasToNewClass
+) {
+    newPublishedFun()
+    newFunExperimentalInThePast()
+    newValExperimentalInThePast
+    NewClassExperimentalInThePast()
+}
+
+@Marker
+fun use3(
+    c3: NewClassExperimentalInThePast,
+    t3: TypeAliasToNewClass
+) {
+    newPublishedFun()
+    newFunExperimentalInThePast()
+    newValExperimentalInThePast
+    NewClassExperimentalInThePast()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/capturedRangeVariableAssignmentBefore13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/capturedRangeVariableAssignmentBefore13.fir.kt
new file mode 100644
index 00000000000..698cda9a46c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/capturedRangeVariableAssignmentBefore13.fir.kt
@@ -0,0 +1,103 @@
+// !LANGUAGE: -ProperForInArrayLoopRangeVariableAssignmentSemantic
+// !DIAGNOSTICS: -UNUSED_VALUE
+// SKIP_TXT
+
+fun testArrayCapturedInLocalFun() {
+    var xs = arrayOf("a", "b", "c")
+
+    fun updateXs() {
+        xs = arrayOf("d", "e", "f")
+    }
+
+    for (x in xs) {
+        println(x)
+        updateXs()
+    }
+}
+
+fun testArrayCapturedInLabmda() {
+    var xs = arrayOf("a", "b", "c")
+
+    val updateXs = { xs = arrayOf("d", "e", "f") }
+
+    for (x in xs) {
+        println(x)
+        updateXs()
+    }
+}
+
+fun testArrayCapturedInInlineLambda() {
+    var xs = arrayOf("a", "b", "c")
+
+    for (x in xs) {
+        println(x)
+        run {
+            xs = arrayOf("d", "e", "f")
+        }
+    }
+}
+
+fun testArrayCapturedInLocalObject() {
+    var xs = arrayOf("a", "b", "c")
+
+    val updateXs = object : () -> Unit {
+        override fun invoke() {
+            xs = arrayOf("d", "e", "f")
+        }
+    }
+
+    for (x in xs) {
+        println(x)
+        updateXs()
+    }
+}
+
+fun testArrayCapturedInLocalClass() {
+    var xs = arrayOf("a", "b", "c")
+
+    class LocalClass {
+        fun updateXs() {
+            xs = arrayOf("d", "e", "f")
+        }
+    }
+
+    val updater = LocalClass()
+
+    for (x in xs) {
+        println(x)
+        updater.updateXs()
+    }
+}
+
+fun testCapturedInLambdaAfterLoop() {
+    // NB false positive
+    var xs = intArrayOf(1, 2, 3)
+    for (x in xs) {
+        println(x)
+        xs = intArrayOf(4, 5, 6)
+    }
+    val lambda = { xs = intArrayOf() }
+    lambda()
+}
+
+fun testCapturedInLambdaInLoopAfterAssignment() {
+    // NB false positive
+    var xs = intArrayOf(1, 2, 3)
+    for (x in xs) {
+        println(x)
+        xs = intArrayOf(4, 5, 6)
+        val lambda = { xs = intArrayOf() }
+        lambda()
+    }
+}
+
+fun testCapturedInNonChangingClosure() {
+    // NB false positive
+    var xs = intArrayOf(1, 2, 3)
+    val lambda = { println(xs) }
+    for (x in xs) {
+        println(x)
+        xs = intArrayOf(4, 5, 6)
+        lambda()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/forInFieldUpdatedInLoopBodyBefore13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/forInFieldUpdatedInLoopBodyBefore13.fir.kt
new file mode 100644
index 00000000000..134a2ccb6cb
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/forInFieldUpdatedInLoopBodyBefore13.fir.kt
@@ -0,0 +1,15 @@
+// !LANGUAGE: -ProperForInArrayLoopRangeVariableAssignmentSemantic
+// !DIAGNOSTICS: -UNUSED_VALUE
+// SKIP_TXT
+
+var xs: IntArray = intArrayOf(1, 2, 3)
+    get() = field
+    set(ys) {
+        var sum = 0
+        for (x in field) {
+            sum = sum * 10 + x
+            field = intArrayOf(4, 5, 6)
+        }
+        if (sum != 123) throw AssertionError("sum=$sum")
+        field = ys
+    }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeLocalDelegatedPropertyAssignmentBefore13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeLocalDelegatedPropertyAssignmentBefore13.fir.kt
new file mode 100644
index 00000000000..64edb6438df
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeLocalDelegatedPropertyAssignmentBefore13.fir.kt
@@ -0,0 +1,16 @@
+// !LANGUAGE: -ProperForInArrayLoopRangeVariableAssignmentSemantic
+// !DIAGNOSTICS: -UNUSED_VALUE
+// SKIP_TXT
+
+class Delegate<T>(var v: T) {
+    operator fun getValue(thisRef: Any?, kProp: Any?) = v
+    operator fun setValue(thisRef: Any?, kProp: Any?, value: T) { v = value }
+}
+
+fun testLocalDelegatedProperty() {
+    var xs by Delegate(arrayOf("a", "b", "c"))
+    for (x in xs) {
+        println(x)
+        xs = arrayOf("d", "e", "f")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeVariableAssignment13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeVariableAssignment13.fir.kt
new file mode 100644
index 00000000000..1689dd22563
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeVariableAssignment13.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +ProperForInArrayLoopRangeVariableAssignmentSemantic
+// !DIAGNOSTICS: -UNUSED_VALUE
+// SKIP_TXT
+
+fun testObjectArray() {
+    var xs = arrayOf("a", "b", "c")
+    for (x in xs) {
+        println(x)
+        xs = arrayOf("d", "e", "f")
+    }
+}
+
+fun testPrimitiveArray() {
+    var xs = intArrayOf(1, 2, 3)
+    for (x in xs) {
+        println(x)
+        xs = intArrayOf(4, 5, 6)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeVariableAssignmentBefore13.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeVariableAssignmentBefore13.fir.kt
new file mode 100644
index 00000000000..746ef0634d7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/forInArrayLoop/rangeVariableAssignmentBefore13.fir.kt
@@ -0,0 +1,39 @@
+// !LANGUAGE: -ProperForInArrayLoopRangeVariableAssignmentSemantic
+// !DIAGNOSTICS: -UNUSED_VALUE
+// SKIP_TXT
+
+fun testObjectArray() {
+    var xs = arrayOf("a", "b", "c")
+    for (x in xs) {
+        println(x)
+        xs = arrayOf("d", "e", "f")
+    }
+}
+
+fun testPrimitiveArray() {
+    var xs = intArrayOf(1, 2, 3)
+    for (x in xs) {
+        println(x)
+        xs = intArrayOf(4, 5, 6)
+    }
+}
+
+var global = arrayOf("a", "b", "c")
+
+fun testGlobalArray() {
+    for (x in global) {
+        println(x)
+        global = arrayOf("d", "e", "f")
+    }
+}
+
+fun testAssignmentNotInLoop() {
+    var xs = intArrayOf(1, 2, 3)
+    println(xs)
+    xs = intArrayOf(7, 8, 9)
+    for (x in xs) {
+        println(x)
+    }
+    xs = intArrayOf(4, 5, 6)
+    println(xs)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/functionLiterals/pseudocodeMemoryOverhead.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/functionLiterals/pseudocodeMemoryOverhead.fir.kt
new file mode 100644
index 00000000000..3816b2688dd
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/functionLiterals/pseudocodeMemoryOverhead.fir.kt
@@ -0,0 +1,371 @@
+import java.util.HashMap
+
+private fun <A> unaryOperation(
+        a: CompileTimeType<A>,
+        functionName: String,
+        operation: Function1<A, Any>,
+        checker: Function1<Long, Long>
+) = UnaryOperationKey(a, functionName) to Pair(operation, checker) as Pair<Function1<Any?, Any>, Function1<Long, Long>>
+
+private fun <A, B> binaryOperation(
+        a: CompileTimeType<A>,
+        b: CompileTimeType<B>,
+        functionName: String,
+        operation: Function2<A, B, Any>,
+        checker: Function2<BigInteger, BigInteger, BigInteger>
+) = BinaryOperationKey(a, b, functionName) to Pair(operation, checker) as Pair<Function2<Any?, Any?, Any>, Function2<BigInteger, BigInteger, BigInteger>>
+
+private data class UnaryOperationKey<A>(val f: CompileTimeType<out A>, val functionName: String)
+//HashMap<BinaryOperationKey<*, *>, Pair<Function2<Any?, Any?, Any>, Function2<BigInteger, BigInteger, BigInteger>>>
+private data class BinaryOperationKey<A, B>(val f: CompileTimeType<out A>, val g: CompileTimeType<out B>, val functionName: String)
+
+private class CompileTimeType<T>
+
+private val BYTE = CompileTimeType<Byte>()
+private val CHAR = CompileTimeType<Char>()
+private val BOOLEAN = CompileTimeType<Boolean>()
+private val DOUBLE = CompileTimeType<Double>()
+private val FLOAT = CompileTimeType<Float>()
+private val INT = CompileTimeType<Int>()
+private val LONG = CompileTimeType<Long>()
+private val SHORT = CompileTimeType<Short>()
+private val STRING = CompileTimeType<String>()
+private val ANY = CompileTimeType<Any>()
+
+
+private val emptyBinaryFun: Function2<BigInteger, BigInteger, BigInteger> = { a, b -> BigInteger("0") }
+private val emptyUnaryFun: Function1<Long, Long> = { a -> 1.toLong() }
+
+private val unaryOperations: HashMap<UnaryOperationKey<*>, Pair<Function1<Any?, Any>, Function1<Long, Long>>>
+        = hashMapOf<UnaryOperationKey<*>, Pair<Function1<Any?, Any>, Function1<Long, Long>>>(
+        unaryOperation(BOOLEAN, "not!", { a -> a.not() }, emptyUnaryFun),
+        unaryOperation(BYTE, "toInt", { a -> a.toInt() }, emptyUnaryFun),
+        unaryOperation(BYTE, "minus", { a -> a.unaryMinus() }, { a -> a.unaryMinus() }),
+        unaryOperation(BYTE, "minus", { a -> a.unaryMinus() }, { a -> a.unaryMinus() }),
+        unaryOperation(BYTE, "toChar", { a -> a.toChar() }, emptyUnaryFun),
+        unaryOperation(BYTE, "toLong", { a -> a.toLong() }, emptyUnaryFun),
+        unaryOperation(BYTE, "plus", { a -> a.unaryPlus() }, emptyUnaryFun),
+        unaryOperation(BYTE, "toFloat", { a -> a.toFloat() }, emptyUnaryFun),
+        unaryOperation(BYTE, "toDouble", { a -> a.toDouble() }, emptyUnaryFun),
+        unaryOperation(BYTE, "toShort", { a -> a.toShort() }, emptyUnaryFun),
+        unaryOperation(BYTE, "toByte", { a -> a.toByte() }, emptyUnaryFun),
+        unaryOperation(CHAR, "toInt", { a -> a.toInt() }, emptyUnaryFun),
+        unaryOperation(CHAR, "toChar", { a -> a.toChar() }, emptyUnaryFun),
+        unaryOperation(CHAR, "toLong", { a -> a.toLong() }, emptyUnaryFun),
+        unaryOperation(CHAR, "toFloat", { a -> a.toFloat() }, emptyUnaryFun),
+        unaryOperation(CHAR, "toDouble", { a -> a.toDouble() }, emptyUnaryFun),
+        unaryOperation(CHAR, "toShort", { a -> a.toShort() }, emptyUnaryFun),
+        unaryOperation(CHAR, "toByte", { a -> a.toByte() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "toInt", { a -> a.toInt() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "minus", { a -> a.unaryMinus() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "toChar", { a -> a.toChar() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "toLong", { a -> a.toLong() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "plus", { a -> a.unaryPlus() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "toFloat", { a -> a.toFloat() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "toDouble", { a -> a.toDouble() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "toShort", { a -> a.toShort() }, emptyUnaryFun),
+        unaryOperation(DOUBLE, "toByte", { a -> a.toByte() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "toInt", { a -> a.toInt() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "minus", { a -> a.unaryMinus() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "toChar", { a -> a.toChar() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "toLong", { a -> a.toLong() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "plus", { a -> a.unaryPlus() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "toFloat", { a -> a.toFloat() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "toDouble", { a -> a.toDouble() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "toShort", { a -> a.toShort() }, emptyUnaryFun),
+        unaryOperation(FLOAT, "toByte", { a -> a.toByte() }, emptyUnaryFun),
+        unaryOperation(INT, "plus", { a -> a.unaryPlus() }, emptyUnaryFun),
+        unaryOperation(INT, "toShort", { a -> a.toShort() }, emptyUnaryFun),
+        unaryOperation(INT, "toByte", { a -> a.toByte() }, emptyUnaryFun),
+        unaryOperation(INT, "inv", { a -> a.inv() }, emptyUnaryFun),
+        unaryOperation(INT, "toInt", { a -> a.toInt() }, emptyUnaryFun),
+        unaryOperation(INT, "minus", { a -> a.unaryMinus() }, { a -> a.unaryMinus() }),
+        unaryOperation(INT, "toChar", { a -> a.toChar() }, emptyUnaryFun),
+        unaryOperation(INT, "toLong", { a -> a.toLong() }, emptyUnaryFun),
+        unaryOperation(INT, "toDouble", { a -> a.toDouble() }, emptyUnaryFun),
+        unaryOperation(INT, "toFloat", { a -> a.toFloat() }, emptyUnaryFun),
+        unaryOperation(LONG, "plus", { a -> a.unaryPlus() }, emptyUnaryFun),
+        unaryOperation(LONG, "toShort", { a -> a.toShort() }, emptyUnaryFun),
+        unaryOperation(LONG, "toByte", { a -> a.toByte() }, emptyUnaryFun),
+        unaryOperation(LONG, "inv", { a -> a.inv() }, emptyUnaryFun),
+        unaryOperation(LONG, "toInt", { a -> a.toInt() }, emptyUnaryFun),
+        unaryOperation(LONG, "minus", { a -> a.unaryMinus() }, { a -> a.unaryMinus() }),
+        unaryOperation(LONG, "toChar", { a -> a.toChar() }, emptyUnaryFun),
+        unaryOperation(LONG, "toLong", { a -> a.toLong() }, emptyUnaryFun),
+        unaryOperation(LONG, "toDouble", { a -> a.toDouble() }, emptyUnaryFun),
+        unaryOperation(LONG, "toFloat", { a -> a.toFloat() }, emptyUnaryFun),
+        unaryOperation(SHORT, "toInt", { a -> a.toInt() }, emptyUnaryFun),
+        unaryOperation(SHORT, "minus", { a -> a.unaryMinus() }, { a -> a.unaryMinus() }),
+        unaryOperation(SHORT, "toChar", { a -> a.toChar() }, emptyUnaryFun),
+        unaryOperation(SHORT, "toLong", { a -> a.toLong() }, emptyUnaryFun),
+        unaryOperation(SHORT, "plus", { a -> a.unaryPlus() }, emptyUnaryFun),
+        unaryOperation(SHORT, "toFloat", { a -> a.toFloat() }, emptyUnaryFun),
+        unaryOperation(SHORT, "toDouble", { a -> a.toDouble() }, emptyUnaryFun),
+        unaryOperation(SHORT, "toShort", { a -> a.toShort() }, emptyUnaryFun),
+        unaryOperation(SHORT, "toByte", { a -> a.toByte() }, emptyUnaryFun),
+        unaryOperation(STRING, "toString", { a -> a.toString() }, emptyUnaryFun)
+)
+
+private val binaryOperations: HashMap<BinaryOperationKey<*, *>, Pair<Function2<Any?, Any?, Any>, Function2<BigInteger, BigInteger, BigInteger>>>
+        = hashMapOf<BinaryOperationKey<*, *>, Pair<Function2<Any?, Any?, Any>, Function2<BigInteger, BigInteger, BigInteger>>>(
+        binaryOperation(BOOLEAN, BOOLEAN, "xor", { a, b -> a.xor(b) }, emptyBinaryFun),
+        binaryOperation(BOOLEAN, BOOLEAN, "or", { a, b -> a.or(b) }, emptyBinaryFun),
+        binaryOperation(BOOLEAN, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(BOOLEAN, BOOLEAN, "and", { a, b -> a.and(b) }, emptyBinaryFun),
+        binaryOperation(BOOLEAN, BOOLEAN, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, BYTE, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(BYTE, DOUBLE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, FLOAT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, INT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(BYTE, LONG, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(BYTE, SHORT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(BYTE, BYTE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, DOUBLE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, FLOAT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, INT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, LONG, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, SHORT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, BYTE, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(BYTE, DOUBLE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, FLOAT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, INT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(BYTE, LONG, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(BYTE, SHORT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(BYTE, BYTE, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(BYTE, DOUBLE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, FLOAT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, INT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(BYTE, LONG, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(BYTE, SHORT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(BYTE, BYTE, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(BYTE, DOUBLE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, FLOAT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, INT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(BYTE, LONG, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(BYTE, SHORT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(BYTE, BYTE, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(BYTE, DOUBLE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, FLOAT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(BYTE, INT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(BYTE, LONG, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(BYTE, SHORT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(BYTE, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(CHAR, CHAR, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(CHAR, CHAR, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(CHAR, INT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(CHAR, INT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(CHAR, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, BYTE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, DOUBLE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, FLOAT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, INT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, LONG, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, SHORT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, BYTE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, DOUBLE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, FLOAT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, INT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, LONG, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, SHORT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, BYTE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, DOUBLE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, FLOAT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, INT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, LONG, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, SHORT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, BYTE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, DOUBLE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, FLOAT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, INT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, LONG, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, SHORT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, BYTE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, DOUBLE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, FLOAT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, INT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, LONG, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, SHORT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, BYTE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, DOUBLE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, FLOAT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, INT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, LONG, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, SHORT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(DOUBLE, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, BYTE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, DOUBLE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, FLOAT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, INT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, LONG, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, SHORT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, BYTE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, DOUBLE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, FLOAT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, INT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, LONG, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, SHORT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, BYTE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, DOUBLE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, FLOAT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, INT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, LONG, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, SHORT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, BYTE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, DOUBLE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, FLOAT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, INT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, LONG, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, SHORT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, BYTE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, DOUBLE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, FLOAT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, INT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, LONG, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, SHORT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, BYTE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, DOUBLE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, FLOAT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, INT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, LONG, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, SHORT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(FLOAT, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(INT, BYTE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(INT, DOUBLE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(INT, FLOAT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(INT, INT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(INT, LONG, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(INT, SHORT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(INT, BYTE, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(INT, DOUBLE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(INT, FLOAT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(INT, INT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(INT, LONG, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(INT, SHORT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(INT, INT, "shl", { a, b -> a.shl(b) }, emptyBinaryFun),
+        binaryOperation(INT, INT, "ushr", { a, b -> a.ushr(b) }, emptyBinaryFun),
+        binaryOperation(INT, BYTE, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(INT, DOUBLE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(INT, FLOAT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(INT, INT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(INT, LONG, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(INT, SHORT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(INT, INT, "shr", { a, b -> a.shr(b) }, emptyBinaryFun),
+        binaryOperation(INT, BYTE, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(INT, DOUBLE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(INT, FLOAT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(INT, INT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(INT, LONG, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(INT, SHORT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(INT, BYTE, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(INT, DOUBLE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(INT, FLOAT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(INT, INT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(INT, LONG, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(INT, SHORT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(INT, INT, "or", { a, b -> a.or(b) }, { a, b -> a.or(b) }),
+        binaryOperation(INT, BYTE, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(INT, DOUBLE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(INT, FLOAT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(INT, INT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(INT, LONG, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(INT, SHORT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(INT, INT, "and", { a, b -> a.and(b) }, { a, b -> a.and(b) }),
+        binaryOperation(INT, INT, "xor", { a, b -> a.xor(b) }, { a, b -> a.xor(b) }),
+        binaryOperation(INT, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(LONG, BYTE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(LONG, DOUBLE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(LONG, FLOAT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(LONG, INT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(LONG, LONG, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(LONG, SHORT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(LONG, BYTE, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(LONG, DOUBLE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(LONG, FLOAT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(LONG, INT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(LONG, LONG, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(LONG, SHORT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(LONG, INT, "shl", { a, b -> a.shl(b) }, emptyBinaryFun),
+        binaryOperation(LONG, INT, "ushr", { a, b -> a.ushr(b) }, emptyBinaryFun),
+        binaryOperation(LONG, BYTE, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(LONG, DOUBLE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(LONG, FLOAT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(LONG, INT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(LONG, LONG, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(LONG, SHORT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(LONG, INT, "shr", { a, b -> a.shr(b) }, emptyBinaryFun),
+        binaryOperation(LONG, BYTE, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(LONG, DOUBLE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(LONG, FLOAT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(LONG, INT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(LONG, LONG, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(LONG, SHORT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(LONG, BYTE, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(LONG, DOUBLE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(LONG, FLOAT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(LONG, INT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(LONG, LONG, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(LONG, SHORT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(LONG, LONG, "or", { a, b -> a.or(b) }, { a, b -> a.or(b) }),
+        binaryOperation(LONG, BYTE, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(LONG, DOUBLE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(LONG, FLOAT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(LONG, INT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(LONG, LONG, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(LONG, SHORT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(LONG, LONG, "and", { a, b -> a.and(b) }, { a, b -> a.and(b) }),
+        binaryOperation(LONG, LONG, "xor", { a, b -> a.xor(b) }, { a, b -> a.xor(b) }),
+        binaryOperation(LONG, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, BYTE, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(SHORT, DOUBLE, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, FLOAT, "minus", { a, b -> a.minus(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, INT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(SHORT, LONG, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(SHORT, SHORT, "minus", { a, b -> a.minus(b) }, { a, b -> a.subtract(b) }),
+        binaryOperation(SHORT, BYTE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, DOUBLE, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, FLOAT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, INT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, LONG, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, SHORT, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, BYTE, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(SHORT, DOUBLE, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, FLOAT, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, INT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(SHORT, LONG, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(SHORT, SHORT, "plus", { a, b -> a.plus(b) }, { a, b -> a.add(b) }),
+        binaryOperation(SHORT, BYTE, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(SHORT, DOUBLE, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, FLOAT, "div", { a, b -> a.div(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, INT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(SHORT, LONG, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(SHORT, SHORT, "div", { a, b -> a.div(b) }, { a, b -> a.divide(b) }),
+        binaryOperation(SHORT, BYTE, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(SHORT, DOUBLE, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, FLOAT, "mod", { a, b -> a.mod(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, INT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(SHORT, LONG, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(SHORT, SHORT, "mod", { a, b -> a.mod(b) }, { a, b -> a.mod(b) }),
+        binaryOperation(SHORT, BYTE, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(SHORT, DOUBLE, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, FLOAT, "times", { a, b -> a.times(b) }, emptyBinaryFun),
+        binaryOperation(SHORT, INT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(SHORT, LONG, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(SHORT, SHORT, "times", { a, b -> a.times(b) }, { a, b -> a.multiply(b) }),
+        binaryOperation(SHORT, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(STRING, ANY, "plus", { a, b -> a.plus(b) }, emptyBinaryFun),
+        binaryOperation(STRING, INT, "get", { a, b -> a.get(b) }, emptyBinaryFun),
+        binaryOperation(STRING, ANY, "equals", { a, b -> a.equals(b) }, emptyBinaryFun),
+        binaryOperation(STRING, STRING, "compareTo", { a, b -> a.compareTo(b) }, emptyBinaryFun)
+)
+
+//from library
+class BigInteger(val value: String) {
+    fun add(o: BigInteger): BigInteger = o
+    fun divide(o: BigInteger): BigInteger = o
+    fun mod(o: BigInteger): BigInteger = o
+    fun multiply(o: BigInteger): BigInteger = o
+    fun subtract(o: BigInteger): BigInteger = o
+    fun or(o: BigInteger): BigInteger = o
+    fun and(o: BigInteger): BigInteger = o
+    fun xor(o: BigInteger): BigInteger = o
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/hugeUnresolvedKotlinxHtml.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/hugeUnresolvedKotlinxHtml.fir.kt
new file mode 100644
index 00000000000..3ee51c17e15
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/hugeUnresolvedKotlinxHtml.fir.kt
@@ -0,0 +1,60 @@
+class A {
+    fun bar() {
+        <!AMBIGUITY!>div<!> {
+            <!AMBIGUITY!>div<!> {
+                <!AMBIGUITY!>div<!> {
+                    <!AMBIGUITY!>div<!> {
+                        <!AMBIGUITY!>div<!> {
+                            <!AMBIGUITY!>div<!> {
+                                <!AMBIGUITY!>div<!> {
+                                    <!AMBIGUITY!>div<!> {
+                                        <!AMBIGUITY!>div<!> {
+                                            <!AMBIGUITY!>div<!> {
+                                                <!AMBIGUITY!>div<!> {
+                                                    <!AMBIGUITY!>div<!> {
+                                                        <!AMBIGUITY!>div<!> {
+                                                            <!AMBIGUITY!>div<!> {
+                                                                <!AMBIGUITY!>div<!> {
+                                                                    <!AMBIGUITY!>div<!> {
+                                                                        <!AMBIGUITY!>div<!> {
+                                                                            <!AMBIGUITY!>div<!> {
+                                                                                <!AMBIGUITY!>div<!> {
+                                                                                    <!AMBIGUITY!>div<!> {
+                                                                                        <!AMBIGUITY!>div<!> {
+                                                                                            <!AMBIGUITY!>div<!> {
+                                                                                                <!AMBIGUITY!>div<!> {
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                    <!UNRESOLVED_REFERENCE!>+<!>(<!UNRESOLVED_REFERENCE!>foo<!> ?: "")
+                                                                                                }
+                                                                                            }
+                                                                                        }
+                                                                                    }
+                                                                                }
+                                                                            }
+                                                                        }
+                                                                    }
+                                                                }
+                                                            }
+                                                        }
+
+                                                    }
+                                                }
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/ifElseJavaList.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/ifElseJavaList.fir.kt
new file mode 100644
index 00000000000..abfc08fe611
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/ifElseJavaList.fir.kt
@@ -0,0 +1,16 @@
+// FILE: Java.java
+
+import java.util.List;
+
+class Java {
+    public static List<Integer> get(List<Integer> o) { return o; }
+}
+
+// FILE: test.kt
+
+import java.util.ArrayList
+
+fun call(): List<Int> {
+    // No errors should be here
+    return Java.get(if (true) ArrayList<Int>() else listOf(0))
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/implicitCastToAny.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/implicitCastToAny.fir.kt
new file mode 100644
index 00000000000..71bd847a1a7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/implicitCastToAny.fir.kt
@@ -0,0 +1,34 @@
+// !WITH_NEW_INFERENCE
+
+var longWords = 0
+val smallWords = hashSetOf<String>()
+
+fun test1(word: String) =
+        run {
+            if (word.length > 4) {
+                longWords++
+            }
+            else {
+                smallWords.add(word)
+            }
+        }
+
+fun test2(word: String) =
+        run {
+            if (word.length > 4) {
+                if (word.startsWith("a")) longWords++
+            }
+            else {
+                smallWords.add(word)
+            }
+        }
+
+fun test3(word: String) =
+        run {
+            if (word.length > 4) {
+                longWords++
+            }
+            else {
+                System.out?.println(word) // Unit?
+            }
+        }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/exactAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/exactAnnotation.fir.kt
new file mode 100644
index 00000000000..8f28742410d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/exactAnnotation.fir.kt
@@ -0,0 +1,12 @@
+//!DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <T, U: T> List<@kotlin.internal.Exact T>.firstTyped(): U = throw Exception()
+
+fun test1(l: List<Number>) {
+
+    val i: Int = l.firstTyped()
+
+    val s: String = l.firstTyped()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/explicitTypeArgumentAsValidInputType.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/explicitTypeArgumentAsValidInputType.fir.kt
new file mode 100644
index 00000000000..25ce8b26d85
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/explicitTypeArgumentAsValidInputType.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -INVISIBLE_MEMBER -INVISIBLE_REFERENCE -UNUSED_PARAMETER
+
+interface Parent
+object ChildA : Parent
+object ChildB : Parent
+
+fun <@kotlin.internal.OnlyInputTypes T> select(a: T, b: T) {}
+
+fun test() {
+    select(ChildA, ChildB) // should be error
+    select<Any>(ChildA, ChildB) // should be ok
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/internalAnnotationsOnTypes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/internalAnnotationsOnTypes.fir.kt
new file mode 100644
index 00000000000..86a57e0c766
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/internalAnnotationsOnTypes.fir.kt
@@ -0,0 +1,30 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <R> Iterable<*>.filterIsInstance1(): List<@kotlin.internal.NoInfer R> = throw Exception()
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <R> List<*>.filterIsInstance2(): @kotlin.internal.NoInfer List<R> = throw Exception()
+
+fun test(list: List<Int>) {
+    list.filterIsInstance1<Int>().map { it * 2 }
+    list.filterIsInstance2<Int>().filter { it > 10 }
+}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <R> foo(t: R): List<@kotlin.internal.NoInfer R> = throw Exception("$t")
+
+fun test() {
+    foo(1).map { it * 2 }
+}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <R> List<R>.foo(): @kotlin.internal.NoInfer R = throw Exception()
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <R> bar(r: R, f: Function1<@kotlin.internal.NoInfer R, Unit>): Nothing = throw Exception()
+
+fun test1() {
+    listOf("").foo().length
+    bar(1) { x -> x + 1 }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/kt26698.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/kt26698.fir.kt
new file mode 100644
index 00000000000..9ae24ea52d4
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/kt26698.fir.kt
@@ -0,0 +1,22 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+open class Base()
+class CX : Base()
+class CY : Base()
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes T> foo(a: T, b: T) {}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes T : Any> fooA(a: T, b: T) {}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes T : Base> fooB(a: T, b: T) {}
+
+
+fun usage(x: CX, y: CY) {
+    foo(x, y) // expected err, got err
+    fooA(x, y) // expected err, got ok
+    fooB(x, y) // expected err, got ok
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/kt29307.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/kt29307.fir.kt
new file mode 100644
index 00000000000..a2cad2370d9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/kt29307.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// ISSUE: KT-29307
+
+fun test_1(map: Map<String, String>) {
+    val x = map[42] // OK
+}
+
+open class A
+
+class B : A()
+
+fun test_2(map: Map<A, String>) {
+    val x = map[42]
+}
+
+fun test_3(m: Map<*, String>) {
+    val x = m[42] // should be ok
+}
+
+fun test_4(m: Map<out Number, String>) {
+    val x = m.get(42) // should be ok
+}
+
+fun test_5(map: Map<B, Int>, a: A) {
+    map.get(a)
+}
+
+fun test_6(map: Map<A, Int>, b: B) {
+    map.get(b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/noInferAndLowPriority.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/noInferAndLowPriority.fir.kt
new file mode 100644
index 00000000000..157865a7ac9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/noInferAndLowPriority.fir.kt
@@ -0,0 +1,16 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.jvm.JvmName("containsAny")
+@kotlin.internal.LowPriorityInOverloadResolution
+public fun <T> Iterable<T>.contains1(element: T): Int = null!!
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+public fun <T> Iterable<T>.contains1(element: @kotlin.internal.NoInfer T): Boolean = null!!
+
+
+fun test() {
+    val a: Boolean = listOf(1).<!AMBIGUITY!>contains1<!>("")
+    val b: Boolean = listOf(1).<!AMBIGUITY!>contains1<!>(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/noInferAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/noInferAnnotation.fir.kt
new file mode 100644
index 00000000000..dc5e2fb9d17
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/noInferAnnotation.fir.kt
@@ -0,0 +1,33 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <T> test1(t1: T, t2: @kotlin.internal.NoInfer T): T = t1
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <T> @kotlin.internal.NoInfer T.test2(t1: T): T = t1
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <T> test3(t1: @kotlin.internal.NoInfer T): T = t1
+
+fun usage() {
+    test1(1, "312")
+    1.test2("")
+    test3("")
+}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <T> List<T>.contains1(e: @kotlin.internal.NoInfer T): Boolean = true
+
+fun test(i: Int?, a: Any, l: List<Int>) {
+    l.contains1(a)
+    l.contains1("")
+    l.contains1(i)
+}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <T> assertEquals1(e1: T, e2: @kotlin.internal.NoInfer T): Boolean = true
+
+fun test(s: String) {
+    assertEquals1(s, 11)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/notNullAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/notNullAnnotation.fir.kt
new file mode 100644
index 00000000000..8d588891567
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/notNullAnnotation.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: +NewInference
+
+// FILE: SmartFMap.java
+
+public class SmartFMap<K, V> implements java.util.Map<K, V> {
+    public static < K, V> SmartFMap<K, V> emptyMap() {
+        return null;
+    }
+
+    public SmartFMap < K, V> plus(@org.jetbrains.annotations.NotNull K key, V value) {
+        return null;
+    }
+}
+
+// FILE: main.kt
+
+class KotlinType
+
+interface TypePredicate : (KotlinType) -> Boolean {
+    override fun invoke(typeToCheck: KotlinType): Boolean
+}
+
+fun <T : Any?> TypePredicate.expectedTypeFor(keys: Iterable<T>): Map<T, TypePredicate> =
+    keys.fold(SmartFMap.emptyMap<T, TypePredicate>()) { map, key ->
+        map.plus(key, this)
+    }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypes.fir.kt
new file mode 100644
index 00000000000..b72dfbd7e0d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypes.fir.kt
@@ -0,0 +1,47 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+public fun <@kotlin.internal.OnlyInputTypes T> Iterable<T>.contains1(element: T): Boolean = null!!
+
+class In<in T>
+
+class Out<out T>
+
+class Inv<T>
+
+fun test_1(list: List<In<Number>>, x: In<Number>, y: In<Int>, z: In<Any>) {
+    list.contains1(x)
+    list.contains1(y)
+    list.contains1(z)
+}
+
+fun test_2(list: List<In<Int>>, x: In<Int>, y: In<Number>, z: In<Any>) {
+    list.contains1(x)
+    list.contains1(y)
+    list.contains1(z)
+}
+
+fun test_3(list: List<Out<Number>>, x: Out<Number>, y: Out<Int>, z: Out<Any>) {
+    list.contains1(x)
+    list.contains1(y)
+    list.contains1(z)
+}
+
+fun test_4(list: List<Out<Int>>, x: Out<Int>, y: Out<Number>, z: Out<Any>) {
+    list.contains1(x)
+    list.contains1(y)
+    list.contains1(z)
+}
+
+fun test_5(list: List<Inv<Number>>, x: Inv<Number>, y: Inv<Int>, z: Inv<Any>) {
+    list.contains1(x)
+    list.contains1(y)
+    list.contains1(z)
+}
+
+fun test_6(list: List<Inv<Int>>, x: Inv<Int>, y: Inv<Number>, z: Inv<Any>) {
+    list.contains1(x)
+    list.contains1(y)
+    list.contains1(z)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAndLowPriority.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAndLowPriority.fir.kt
new file mode 100644
index 00000000000..08a1cd0160a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAndLowPriority.fir.kt
@@ -0,0 +1,26 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.jvm.JvmName("containsAny")
+@kotlin.internal.LowPriorityInOverloadResolution
+public fun <T> Iterable<T>.contains1(element: T): Int = null!!
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+public fun <@kotlin.internal.OnlyInputTypes T> Iterable<T>.contains1(element: T): Boolean = null!!
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@JvmName("getAny")
+@kotlin.internal.LowPriorityInOverloadResolution
+public fun <K, V> Map<K, V>.get1(key: Any?): Int = null!!
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+public fun <@kotlin.internal.OnlyInputTypes K, V> Map<out K, V>.get1(key: K): V? = null!!
+
+fun test(map: Map<Int, String>) {
+    val a: Int = listOf(1).<!AMBIGUITY!>contains1<!>("")
+    val b: Boolean = listOf(1).<!AMBIGUITY!>contains1<!>(1)
+
+    val c: String? = map.get1("")
+    val d: String? = map.get1(1)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAndTopLevelCapturedTypes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAndTopLevelCapturedTypes.fir.kt
new file mode 100644
index 00000000000..5236ae74b83
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAndTopLevelCapturedTypes.fir.kt
@@ -0,0 +1,73 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+
+class Inv<T>
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes K> Inv<out K>.onlyOut(e: K) {}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes K : Number> Inv<out K>.onlyOutUB(e: K) {}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes K> Inv<in K>.onlyIn(e: K) {}
+
+fun test(
+    invStar: Inv<*>,
+    invOut: Inv<out Number>,
+    invIn: Inv<in Number>
+) {
+    invStar.onlyOut("str")
+    invOut.onlyOut(42)
+    invOut.onlyOut(1L)
+
+    invOut.<!INAPPLICABLE_CANDIDATE!>onlyOutUB<!>("str")
+    invStar.<!INAPPLICABLE_CANDIDATE!>onlyOutUB<!>(0)
+    invOut.onlyOutUB(42)
+    invOut.onlyOutUB(1L)
+
+    invIn.<!INAPPLICABLE_CANDIDATE!>onlyIn<!>("str")
+    invIn.onlyIn(42)
+    invIn.onlyIn(1L)
+}
+
+// From KT-32157
+fun test2(value: Any?) {
+    val result = (value as? Map<*, *>)?.get("result")
+}
+
+// From KT-32116
+fun test3(h: HashMap<*, *>) {
+    val a = <!AMBIGUITY!>h["str"]<!>
+    val b = <!AMBIGUITY!>h[1]<!>
+    val c = <!AMBIGUITY!>h["other"]<!> as? Double
+}
+
+// From KT-32218
+fun test4() {
+    val map: Map<out Any, Any> = mapOf(
+        true to true,
+        1L to 1L
+    )
+    val test = map[1L]
+}
+
+// From KT-32235
+
+class A<T> {
+    val children = mutableListOf<B<T>>()
+}
+
+class B<T>
+
+class Test5 {
+    var a: A<*>? = null
+    var b: B<*>? = null
+        set(value) {
+            if (value != null) {
+                val a = a
+                require(a != null && value in a.children)
+            }
+            field = value
+        }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAnnotationWithPlatformTypes.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAnnotationWithPlatformTypes.fir.kt
new file mode 100644
index 00000000000..154c475e0c7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesAnnotationWithPlatformTypes.fir.kt
@@ -0,0 +1,19 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER
+
+//FILE:Foo.java
+
+public class Foo {
+    public static String foo() {
+        return null;
+    }
+}
+
+//FILE:Bar.kt
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes T> assertEquals1(t1: T, t2: T) {}
+
+fun test() {
+    assertEquals1(null, Foo.foo())
+    assertEquals1("", Foo.foo())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesCaptured.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesCaptured.fir.kt
new file mode 100644
index 00000000000..a75fd93f946
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesCaptured.fir.kt
@@ -0,0 +1,113 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+// Issue: KT-26698
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+public fun <@kotlin.internal.OnlyInputTypes T> Iterable<T>.contains1(element: T): Boolean = null!!
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+public fun <@kotlin.internal.OnlyInputTypes T> Iterable<T>.foo(element: T): T = null!!
+
+class Inv<T>
+class Inv2<T, R>
+
+class In<in T>
+class Out<out T>
+
+// -------------------------------------------------------
+
+fun test_0(x: Inv2<in Number, out Number>, list: List<Inv2<Any, Int>>) {
+    list.foo(x)
+}
+
+// ------------------------- Inv -------------------------
+
+fun test_1(x: Inv<Number>, list: List<Inv<Number>>) {
+    list.contains1(x)
+}
+
+fun test_2(x: Inv<Number>, list: List<Inv<Int>>) {
+    list.contains1(x)
+}
+
+fun test_3(x: Inv<Number>, list: List<Inv<Any>>) {
+    list.contains1(x)
+}
+
+fun test_4(x: Inv<in Number>, list: List<Inv<Any>>) {
+    list.contains1(x)
+}
+
+fun test_5(x: Inv<in Number>, list: List<Inv<Number>>) {
+    list.contains1(x)
+}
+
+fun test_6(x: Inv<in Number>, list: List<Inv<Int>>) {
+    list.contains1(x)
+}
+
+fun test_7(x: Inv<out Number>, list: List<Inv<Any>>) {
+    list.contains1(x)
+}
+
+fun test_8(x: Inv<out Number>, list: List<Inv<Number>>) {
+    list.contains1(x)
+}
+
+fun test_9(x: Inv<out Number>, list: List<Inv<Int>>) {
+    list.contains1(x)
+}
+
+// ------------------------- In -------------------------
+
+fun test_11(x: In<Number>, list: List<In<Number>>) {
+    list.contains1(x)
+}
+
+fun test_12(x: In<Number>, list: List<In<Int>>) {
+    list.contains1(x)
+}
+
+fun test_13(x: In<Number>, list: List<In<Any>>) {
+    list.contains1(x)
+}
+
+// ------------------------- Out -------------------------
+
+fun test_21(x: Out<Number>, list: List<Out<Number>>) {
+    list.contains1(x)
+}
+
+fun test_22(x: Out<Number>, list: List<Out<Int>>) {
+    list.contains1(x)
+}
+
+fun test_23(x: Out<Number>, list: List<Out<Any>>) {
+    list.contains1(x)
+}
+
+// --------------------------------------------------------
+
+fun test_31(x: Inv<Number>, list: List<Inv<in Number>>) {
+    list.contains1(x)
+}
+
+fun test_32(x: Inv<Number>, list: List<Inv<in Int>>) {
+    list.contains1(x)
+}
+
+fun test_33(x: Inv<Number>, list: List<Inv<in Any>>) {
+    list.contains1(x)
+}
+
+fun test_34(x: Inv<Number>, list: List<Inv<out Number>>) {
+    list.contains1(x)
+}
+
+fun test_35(x: Inv<Number>, list: List<Inv<out Int>>) {
+    list.contains1(x)
+}
+
+fun test_36(x: Inv<Number>, list: List<Inv<out Any>>) {
+    list.contains1(x)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesWithVarargs.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesWithVarargs.fir.kt
new file mode 100644
index 00000000000..4e73147cdc6
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/onlyInputTypesWithVarargs.fir.kt
@@ -0,0 +1,26 @@
+fun test1(ns: String?, vararg nullableStrs: String?) {
+    nullableStrs.contains("x")
+    nullableStrs.contains(ns)
+    "x" in nullableStrs
+    ns in nullableStrs
+}
+
+fun test2(ns: String?, vararg nonNullableStrs: String) {
+    nonNullableStrs.contains("x")
+    nonNullableStrs.contains(ns)
+    "x" in nonNullableStrs
+    ns in nonNullableStrs
+}
+
+fun test3(ns: String?, nullableStrs: Array<out String?>, nonNullableStrs: Array<out String>) {
+    nullableStrs.contains("x")
+    nonNullableStrs.contains("x")
+
+    nullableStrs.contains(ns)
+    nonNullableStrs.contains(ns)
+
+    "x" in nullableStrs
+    "x" in nonNullableStrs
+    ns in nullableStrs
+    ns in nonNullableStrs
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/propagationOfNoInferAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/propagationOfNoInferAnnotation.fir.kt
new file mode 100644
index 00000000000..7f7e91045c1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/propagationOfNoInferAnnotation.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+private object TopLevelTypeVariable {
+    @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+    fun <T> foo(): @kotlin.internal.NoInfer T = TODO()
+
+    fun <K> bar(k: K) {}
+
+    fun test() {
+        bar(foo<Int>())
+    }
+}
+
+private object NestedTypeVariable {
+    class Inv<T>
+
+    @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+    fun <T> foo(): Inv<@kotlin.internal.NoInfer T> = TODO()
+
+    fun <K> bar(p: Inv<K>) {}
+
+    fun test() {
+        bar(foo<String>())
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/resolveWithOnlyInputTypesAnnotation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/resolveWithOnlyInputTypesAnnotation.fir.kt
new file mode 100644
index 00000000000..6c9fe7a7efa
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/annotationsForResolve/resolveWithOnlyInputTypesAnnotation.fir.kt
@@ -0,0 +1,25 @@
+//!DIAGNOSTICS: -UNUSED_PARAMETER
+// !WITH_NEW_INFERENCE
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+fun <@kotlin.internal.OnlyInputTypes T> assertEquals1(t1: T, t2: T) {}
+
+open class A
+class B: A()
+class C: A()
+class D
+
+fun test1(a: A, b: B, c: C) {
+    assertEquals1(a, b)
+    assertEquals1(b, c)
+
+    assertEquals1(3, 3)
+    assertEquals1(1 or 2, 2 or 1)
+}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+public fun <@kotlin.internal.OnlyInputTypes T> expect1(expected: T, block: () -> T) {}
+
+fun test() {
+    expect1(2) { byteArrayOf(1, 2, 3).indexOf(3) }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/arrayConstructor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/arrayConstructor.fir.kt
new file mode 100644
index 00000000000..919b8578b2d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/arrayConstructor.fir.kt
@@ -0,0 +1,14 @@
+// !CHECK_TYPE
+
+package b
+
+fun bar() {
+    val a1 = Array(1, {i: Int -> i})
+    val a2 = Array(1, {i: Int -> "$i"})
+    val a3 = Array(1, {it})
+
+    checkSubtype<Array<Int>>(a1)
+    checkSubtype<Array<String>>(a2)
+    checkSubtype<Array<Int>>(a3)
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/integerLiterals.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/integerLiterals.fir.kt
new file mode 100644
index 00000000000..a024bc2848f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/integerLiterals.fir.kt
@@ -0,0 +1,24 @@
+// !LANGUAGE: +NewInference
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -USELESS_ELVIS -UNUSED_EXPRESSION
+
+class X {
+    fun toLong(): Long? = TODO()
+}
+
+fun getLong(): Long = TODO()
+
+fun test_1(list: List<X>) {
+    val props = list.map { it.toLong() ?: 0 }
+    props
+}
+
+fun test_2(cond: Boolean) {
+    val props = if (cond) getLong() else 0
+    props
+}
+
+fun test_3(list: List<X>) {
+    val props = list.map { Pair(it.toLong() ?: 0, it.toLong() ?: 0) }
+    props
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/intersectionInputType.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/intersectionInputType.fir.kt
new file mode 100644
index 00000000000..0b312e318b3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/intersectionInputType.fir.kt
@@ -0,0 +1,12 @@
+// !LANGUAGE: +NewInference
+
+import kotlin.test.assertEquals
+
+fun test() {
+    val u = when (true) {
+        true -> 42
+        else -> 1.0
+    }
+
+    assertEquals(42, u)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt11266.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt11266.fir.kt
new file mode 100644
index 00000000000..e7ceb67e29a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt11266.fir.kt
@@ -0,0 +1,4 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+
+fun foo(first: Array<Any?>, second: Array<Any?>) = <!INAPPLICABLE_CANDIDATE!>Pair<!>(first.<!INAPPLICABLE_CANDIDATE!>toCollection<!>(), second.<!INAPPLICABLE_CANDIDATE!>toCollection<!>())
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt12008.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt12008.fir.kt
new file mode 100644
index 00000000000..c6128f73444
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt12008.fir.kt
@@ -0,0 +1,12 @@
+// FULL_JDK
+
+import java.util.*
+
+fun foo(o: Optional<String>) {}
+
+class Test(nullable: String?) {
+    private val nullableOptional = Optional.ofNullable(nullable)
+    fun doIt() {
+        foo(nullableOptional)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt1558.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt1558.fir.kt
new file mode 100644
index 00000000000..ab5614de074
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt1558.fir.kt
@@ -0,0 +1,26 @@
+// !CHECK_TYPE
+
+//KT-1558 Exception while analyzing
+package j
+
+fun <T : Any> T?.sure() : T = this!!
+
+fun <E> List<*>.toArray(ar: Array<E>): Array<E> = ar
+
+fun testArrays(ci: List<Int?>, cii: List<Int?>?) {
+    val c1: Array<Int?> = cii.sure().<!INAPPLICABLE_CANDIDATE!>toArray<!>(Array<Int?>)
+
+    val c2: Array<Int?> = ci.toArray(<!INAPPLICABLE_CANDIDATE!>Array<!><Int?>())
+
+    val c3 = <!INAPPLICABLE_CANDIDATE!>Array<!><Int?>()
+
+    val c4 = ci.toArray<Int?>(<!INAPPLICABLE_CANDIDATE!>Array<!><Int?>())
+
+    val c5 = ci.toArray(<!INAPPLICABLE_CANDIDATE!>Array<!><Int?>())
+
+    checkSubtype<Array<Int?>>(c1)
+    checkSubtype<Array<Int?>>(c2)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Array<Int?>>(c3)
+    checkSubtype<Array<Int?>>(c4)
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Array<Int?>>(c5)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt27772.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt27772.fir.kt
new file mode 100644
index 00000000000..12ae9041270
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt27772.fir.kt
@@ -0,0 +1,9 @@
+// !WITH_NEW_INFERENCE
+
+fun <T> foo(resources: List<T>) {
+    resources.map { runCatching { it } }.mapNotNull { it.getOrNull() }
+}
+
+fun <T: Any> bar(resources: List<T>) {
+    resources.map { runCatching { it } }.mapNotNull { it.getOrNull() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt30292.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt30292.fir.kt
new file mode 100644
index 00000000000..1c164720a43
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt30292.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: +NewInference
+
+fun test(ls: List<String>) {
+    ls.takeIf(Collection<*>::isNotEmpty)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt32345.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt32345.fir.kt
new file mode 100644
index 00000000000..2de407aaef6
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt32345.fir.kt
@@ -0,0 +1,49 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+import kotlin.reflect.KProperty
+import kotlin.properties.ReadWriteProperty
+
+class CleanupTestExample {
+    val cleanUpBlocks: MutableList<Pair<Any, (Any) -> Unit>> = mutableListOf()
+
+    class CleaningDelegate<T : Any?>(
+        initialValue: T? = null,
+        val cleanupBlocks: MutableList<Pair<Any, (Any) -> Unit>>,
+        val block: (T) -> Unit
+    ) : ReadWriteProperty<Any?, T> {
+        private var value: T? = initialValue
+
+        init {
+            addCleanupBlock(initialValue)
+        }
+
+        override fun getValue(thisRef: Any?, property: KProperty<*>): T {
+            return value ?: throw IllegalStateException("Property ${property.name} should be initialized before get.")
+        }
+
+        @Suppress("UNCHECKED_CAST")
+        override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
+            addCleanupBlock(value)
+            this.value = value
+        }
+
+        fun addCleanupBlock(value: T?) {
+            if (value != null) {
+                @Suppress("UNCHECKED_CAST")
+                cleanupBlocks.add((value to block) as Pair<Any, (Any) -> Unit>)
+            }
+
+        }
+    }
+
+    data class TestHolder(val num: Int)
+
+    fun <T : Any?> cleanup(initialValue: T? = null, block: (T) -> Unit) = CleaningDelegate(initialValue, cleanUpBlocks, block)
+
+    fun testWithCleanup() {
+        val testHolder = TestHolder(1)
+
+        var thing: TestHolder by CleaningDelegate(testHolder, cleanupBlocks = cleanUpBlocks, block = { println("cleaning up $it") })
+        var thing2: TestHolder by cleanup(testHolder) { println("cleaning up $it") }
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt3458.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt3458.fir.kt
new file mode 100644
index 00000000000..8fc7524f41e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt3458.fir.kt
@@ -0,0 +1,9 @@
+// !CHECK_TYPE
+
+import java.io.File
+
+fun test() {
+    val dir = File("dir")
+    val files = dir.listFiles()?.toList() ?: listOf() // error
+    files checkType { <!UNRESOLVED_REFERENCE!>_<!><List<File>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt4975.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt4975.fir.kt
new file mode 100644
index 00000000000..7a9267a731e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt4975.fir.kt
@@ -0,0 +1,10 @@
+// !CHECK_TYPE
+
+fun <T> bar(f: () -> T) : T = f()
+
+fun test(map: MutableMap<Int, Int>) {
+    val r = bar {
+        map[1] = 2
+    }
+    r checkType { <!UNRESOLVED_REFERENCE!>_<!><Unit>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inline/inlineOnlySuppressesNothingToInline.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inline/inlineOnlySuppressesNothingToInline.fir.kt
new file mode 100644
index 00000000000..6bac4f49b01
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inline/inlineOnlySuppressesNothingToInline.fir.kt
@@ -0,0 +1,31 @@
+// !DIAGNOSTICS: -INVISIBLE_MEMBER -INVISIBLE_REFERENCE -UNUSED_PARAMETER -NULLABLE_INLINE_PARAMETER
+
+@kotlin.internal.InlineOnly
+inline fun test() {
+
+}
+
+@kotlin.internal.InlineOnly
+inline fun test3(noinline s : (Int) -> Int) {
+
+}
+
+@kotlin.internal.InlineOnly
+inline fun test4(noinline s : Int.() -> Int) {
+
+}
+
+@kotlin.internal.InlineOnly
+inline fun Function1<Int, Int>?.test5() {
+
+}
+
+@kotlin.internal.InlineOnly
+inline fun Function1<Int, Int>?.test6() {
+
+}
+
+@kotlin.internal.InlineOnly
+inline fun test2(s : ((Int) -> Int)?) {
+
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inline/synchronizedOnInline.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/inline/synchronizedOnInline.fir.kt
new file mode 100644
index 00000000000..fecc57b0e10
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/inline/synchronizedOnInline.fir.kt
@@ -0,0 +1,16 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+@Synchronized
+inline fun foo(f: () -> Unit): Unit = f()
+
+var bar: String
+    @Synchronized
+    inline get() = ""
+    @Synchronized
+    inline set(value) {}
+
+inline var baz: String
+    @Synchronized
+    get() = ""
+    @Synchronized
+    set(value) {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/instar.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/instar.fir.kt
new file mode 100644
index 00000000000..74992217ab5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/instar.fir.kt
@@ -0,0 +1,11 @@
+// Reproduces exception in TypeResolver.kt: EA-66870
+
+import java.util.ArrayList
+
+abstract class J {
+    public abstract fun <T : Collection<S>, S : List<in *>> foo(x: T)
+    fun bar() {
+        val s = ArrayList<ArrayList<Int>>()
+        foo(s)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContains.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContains.fir.kt
new file mode 100644
index 00000000000..ec611b6920f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContains.fir.kt
@@ -0,0 +1,79 @@
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+class A : java.util.concurrent.ConcurrentHashMap<String, Int>() {
+    operator fun contains(x: Char): Boolean = true
+}
+class B : java.util.concurrent.ConcurrentHashMap<String, Int>() {
+    override fun contains(value: Any?): Boolean {
+        return super.contains(value)
+    }
+}
+
+class C : java.util.concurrent.ConcurrentHashMap<String, Int>() {
+    operator override fun contains(value: Any?): Boolean {
+        return super.contains(value)
+    }
+}
+
+fun main() {
+    val hm = java.util.concurrent.<!UNRESOLVED_REFERENCE!>ConcurrentHashMap<!><String, Int>()
+    "" in hm
+    "" !in hm
+    1 <!AMBIGUITY, UNRESOLVED_REFERENCE!>!in<!> hm
+    2 <!AMBIGUITY!>in<!> hm
+
+    hm.contains("")
+    hm.<!AMBIGUITY!>contains<!>(1)
+
+    "" in (hm as Map<String, Int>)
+    "" !in (hm as Map<String, Int>)
+    1 in (hm as Map<String, Int>)
+    1 !in (hm as Map<String, Int>)
+
+    val a = A()
+    "" in a
+    "" !in a
+    1 !in a
+    2 in a
+
+    ' ' in a
+    ' ' !in a
+    a.contains("")
+    a.contains(1)
+
+    "" in (a as Map<String, Int>)
+    "" !in (a as Map<String, Int>)
+    1 in (a as Map<String, Int>)
+    1 !in (a as Map<String, Int>)
+
+    val b = B()
+    "" in b
+    "" !in b
+    1 !in b
+    2 in b
+
+    b.contains("")
+    b.contains(1)
+
+    "" in (b as Map<String, Int>)
+    "" !in (b as Map<String, Int>)
+    1 in (b as Map<String, Int>)
+    1 !in (b as Map<String, Int>)
+
+    // Actually, we could've allow calls here because the owner explicitly declared as operator, but semantics is still weird
+    val c = C()
+    "" in c
+    "" !in c
+    1 !in c
+    2 in c
+
+    c.contains("")
+    c.contains(1)
+
+    "" in (c as Map<String, Int>)
+    "" !in (c as Map<String, Int>)
+    1 in (c as Map<String, Int>)
+    1 !in (c as Map<String, Int>)
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContainsError.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContainsError.fir.kt
new file mode 100644
index 00000000000..187378a6acc
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContainsError.fir.kt
@@ -0,0 +1,80 @@
+// !LANGUAGE: +ProhibitConcurrentHashMapContains
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+class A : java.util.concurrent.ConcurrentHashMap<String, Int>() {
+    operator fun contains(x: Char): Boolean = true
+}
+class B : java.util.concurrent.ConcurrentHashMap<String, Int>() {
+    override fun contains(value: Any?): Boolean {
+        return super.contains(value)
+    }
+}
+
+class C : java.util.concurrent.ConcurrentHashMap<String, Int>() {
+    operator override fun contains(value: Any?): Boolean {
+        return super.contains(value)
+    }
+}
+
+fun main() {
+    val hm = java.util.concurrent.<!UNRESOLVED_REFERENCE!>ConcurrentHashMap<!><String, Int>()
+    "" in hm
+    "" !in hm
+    1 <!AMBIGUITY, UNRESOLVED_REFERENCE!>!in<!> hm
+    2 <!AMBIGUITY!>in<!> hm
+
+    hm.contains("")
+    hm.<!AMBIGUITY!>contains<!>(1)
+
+    "" in (hm as Map<String, Int>)
+    "" !in (hm as Map<String, Int>)
+    1 in (hm as Map<String, Int>)
+    1 !in (hm as Map<String, Int>)
+
+    val a = A()
+    "" in a
+    "" !in a
+    1 !in a
+    2 in a
+
+    ' ' in a
+    ' ' !in a
+    a.contains("")
+    a.contains(1)
+
+    "" in (a as Map<String, Int>)
+    "" !in (a as Map<String, Int>)
+    1 in (a as Map<String, Int>)
+    1 !in (a as Map<String, Int>)
+
+    val b = B()
+    "" in b
+    "" !in b
+    1 !in b
+    2 in b
+
+    b.contains("")
+    b.contains(1)
+
+    "" in (b as Map<String, Int>)
+    "" !in (b as Map<String, Int>)
+    1 in (b as Map<String, Int>)
+    1 !in (b as Map<String, Int>)
+
+    // Actually, we could've allow calls here because the owner explicitly declared as operator, but semantics is still weird
+    val c = C()
+    "" in c
+    "" !in c
+    1 !in c
+    2 in c
+
+    c.contains("")
+    c.contains(1)
+
+    "" in (c as Map<String, Int>)
+    "" !in (c as Map<String, Int>)
+    1 in (c as Map<String, Int>)
+    1 !in (c as Map<String, Int>)
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/java/functionN.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/java/functionN.fir.kt
new file mode 100644
index 00000000000..428ca22b761
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/java/functionN.fir.kt
@@ -0,0 +1,58 @@
+// !DIAGNOSTICS: -UNUSED_ANONYMOUS_PARAMETER
+
+// FILE: KI.kt
+
+interface KI {
+    fun manyParams(x: (String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String, String) -> Unit)
+}
+
+// FILE: A.java
+
+import kotlin.jvm.functions.FunctionN;
+
+public class A implements KI {
+    public FunctionN<?> field;
+
+    public A(FunctionN<?> w) {}
+
+    public void foo(FunctionN<String> x) {
+
+    }
+
+    public FunctionN<?> bar() {
+        return null;
+    }
+
+    public void baz(java.util.List<FunctionN<?>> z) {
+
+    }
+
+    public void manyParams(FunctionN<Unit> x) {
+
+    }
+}
+
+// FILE: main.kt
+
+fun <T> any(): T = null!!
+
+fun main() {
+    val a: A = A(null)
+
+    a.field.hashCode();
+    a.field = null;
+
+    a.foo(null)
+    a.bar()
+    a.baz(listOf())
+
+    a.<!AMBIGUITY!>manyParams<!>(null)
+    a.manyParams(any<kotlin.jvm.functions.FunctionN<Unit>>())
+
+    // Potentially, this would have better to forbid calling manyParams, too.
+    // But it might be complicated because we need to match that it is an override
+    // Seems to be fine because `A::manyParams` is anyway an override in JVM and can be called with (a as K)
+    a.manyParams {
+            x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15, x16, x17, x18, x19, x20, x21, x22, x23, x24, x25, x26, x27, x28, x29, x30, x31, x32 ->
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/java/inheritedFunctionN.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/java/inheritedFunctionN.fir.kt
new file mode 100644
index 00000000000..8ca90683387
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/java/inheritedFunctionN.fir.kt
@@ -0,0 +1,16 @@
+
+// FILE: A.java
+
+import kotlin.jvm.functions.FunctionN;
+
+public class A {
+    public void foo(FunctionN<?> w) { }
+}
+
+// FILE: main.kt
+
+class B : A()
+
+fun foo() {
+    object : A() {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/java/patternCompileCallableReference.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/java/patternCompileCallableReference.fir.kt
new file mode 100644
index 00000000000..ed1d3830493
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/java/patternCompileCallableReference.fir.kt
@@ -0,0 +1,8 @@
+// FULL_JDK
+// SKIP_TXT
+
+import java.util.regex.Pattern
+
+val strs: List<String> = listOf("regex1", "regex2")
+
+val patterns: List<Pattern> = strs.map(Pattern::compile)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/javaClassOnCompanion.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/javaClassOnCompanion.fir.kt
new file mode 100644
index 00000000000..1a1936414f9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/javaClassOnCompanion.fir.kt
@@ -0,0 +1,32 @@
+package test
+
+class A {
+    companion object
+}
+
+object O
+
+enum class E {
+    ENTRY
+}
+
+
+val a0 = A.javaClass
+val a1 = test.A.javaClass
+val a2 = A.Companion.javaClass
+val a3 = A::class.java
+val a4 = test.A::class.java
+val a5 = A.Companion::class.java
+
+val o0 = O.javaClass
+val o1 = O::class.java
+
+val e0 = E.javaClass
+val e1 = E::class.java
+val e2 = E.ENTRY.javaClass
+
+val int0 = Int.javaClass
+val int1 = Int::class.java
+
+val string0 = String.javaClass
+val string1 = String::class.java
diff --git a/compiler/testData/diagnostics/testsWithStdLib/javaForKClass.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/javaForKClass.fir.kt
new file mode 100644
index 00000000000..2b484f7a656
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/javaForKClass.fir.kt
@@ -0,0 +1,28 @@
+// !CHECK_TYPE
+
+// FILE: A.java
+import kotlin.reflect.KClass;
+
+public class A {
+    public static A getA() {
+        return null;
+    }
+
+    public static KClass<A> getKClass() {
+        return null;
+    }
+}
+
+
+// types checked by txt file
+
+// FILE: 1.kt
+inline fun <reified X> test1() = <!OTHER_ERROR!>X<!>::class.<!INAPPLICABLE_CANDIDATE!>java<!>
+inline fun <reified X : Any> test2() = <!OTHER_ERROR!>X<!>::class.<!INAPPLICABLE_CANDIDATE!>java<!>
+inline fun <reified X : Any?> test3() = <!OTHER_ERROR!>X<!>::class.<!INAPPLICABLE_CANDIDATE!>java<!>
+inline fun <reified X : Number> test4() = <!OTHER_ERROR!>X<!>::class.<!INAPPLICABLE_CANDIDATE!>java<!>
+inline fun <reified X : Number?> test5() = <!OTHER_ERROR!>X<!>::class.<!INAPPLICABLE_CANDIDATE!>java<!>
+
+fun test6() = A.getA()::class.java
+fun test7() = A.getKClass().java
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/kt7585/delegate.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/kt7585/delegate.fir.kt
new file mode 100644
index 00000000000..3867393a3f2
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/kt7585/delegate.fir.kt
@@ -0,0 +1,76 @@
+// !WITH_NEW_INFERENCE
+// NI_EXPECTED_FILE
+// JAVAC_EXPECTED_FILE
+// FILE: Base.java
+
+public interface Base {}
+
+// FILE: Other.java
+
+public interface Other {}
+
+// FILE: Derived.java
+
+public final class Derived<T> implements Base, Other {}
+
+// FILE: Exotic.java
+
+public final class Exotic implements Base, Other {
+
+    int x;
+
+    Exotic(int x) {
+        this.x = x;
+    }
+}
+
+// FILE: Properties.java
+
+import kotlin.jvm.functions.Function0;
+
+class Val<T> {
+
+    Function0<T> initializer;
+
+    Val(Function0<T> initializer) {
+        this.initializer = initializer;
+    }
+
+    T getValue(Object instance, Object metadata) {
+        return initializer.invoke();
+    }
+}
+
+class Properties {
+    static <T> Val<T> calcVal(Function0<T> initializer) {
+        return new Val<T>(initializer);
+    }
+}
+
+// FILE: My.kt
+
+open class Wrapper<out T: Base>(val v: T)
+
+class DerivedWrapper(v: Derived<*>): Wrapper<Derived<*>>(v)
+
+class ExoticWrapper(v: Exotic): Wrapper<Exotic>(v)
+
+object MyBase {
+
+    fun derived() = Derived<String>()
+    fun exotic(x: Int) = Exotic(x)
+
+    fun derivedWrapper() = DerivedWrapper(derived())
+    fun exoticWrapper(x: Int) = ExoticWrapper(exotic(x))
+}
+
+class My(val x: Int) {
+    val wrapper/*: Wrapper<*>*/ by Properties.calcVal {
+        val y = x + 1
+        when {
+            y > 0 -> MyBase.derivedWrapper()
+            x < 0 -> MyBase.exoticWrapper(x)
+            else  -> throw java.lang.<!UNRESOLVED_REFERENCE!>NullPointerException<!>("")
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/kt8050.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/kt8050.fir.kt
new file mode 100644
index 00000000000..fa84db2e1e8
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/kt8050.fir.kt
@@ -0,0 +1,11 @@
+private class X
+
+private operator fun X?.plus(p: Int) = X()
+
+class C {
+    private val map = hashMapOf<String, X>()
+
+    fun f() {
+        map[""] += 1
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/kt9078.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/kt9078.fir.kt
new file mode 100644
index 00000000000..12aa7946ceb
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/kt9078.fir.kt
@@ -0,0 +1,12 @@
+// KT-9078 (NPE in control flow analysis); EA-71535
+abstract class KFunctionKt9005WorkAround<out R: Any?>(private val _functionInstance: Function<R>) {
+    private val _reflectedFunction: kotlin.reflect.KFunction<R> = _functionInstance.<!UNRESOLVED_REFERENCE!>reflect<!>() ?: throw IllegalStateException("")
+
+    private val _parameters: List<kotlin.reflect.KParameter> = run {
+        _functionInstance.javaClass.methods.first().<!UNRESOLVED_REFERENCE!>parameters<!>.<!AMBIGUITY!>map<!> {
+            object : kotlin.reflect.KParameter {
+                override val index: Int = 0
+            }
+        }
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/kt9985.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/kt9985.fir.kt
new file mode 100644
index 00000000000..a99da78ab1c
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/kt9985.fir.kt
@@ -0,0 +1,3 @@
+fun foo(l: List<String>?) {
+  Pair(l?.joinToString(), "")
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/lateinit/isInitialized.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/lateinit/isInitialized.fir.kt
new file mode 100644
index 00000000000..681023b0659
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/lateinit/isInitialized.fir.kt
@@ -0,0 +1,87 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -NOTHING_TO_INLINE
+// FILE: test.kt
+
+interface Base {
+    var x: String
+}
+
+open class Foo : Base {
+    override lateinit var x: String
+    private lateinit var y: String
+
+    var nonLateInit: Int = 1
+
+    fun ok() {
+        val b: Boolean = this::x.isInitialized
+
+        val otherInstance = Foo()
+        otherInstance::x.isInitialized
+
+        (this::x).isInitialized
+        (@Suppress("ALL") (this::x)).isInitialized
+
+        object {
+            fun local() {
+                class Local {
+                    val xx = this@Foo::x.isInitialized
+                    val yy = this@Foo::y.isInitialized
+                }
+            }
+        }
+    }
+
+    fun onLiteral() {
+        val p = this::x
+        p.isInitialized
+    }
+
+    fun onNonLateinit() {
+        this::nonLateInit.isInitialized
+    }
+
+    inline fun inlineFun() {
+        this::x.isInitialized
+
+        object {
+            val z = this@Foo::x.isInitialized
+        }
+    }
+
+    inner class InnerSubclass : Foo() {
+        fun innerOk() {
+            // This is access to Foo.x declared lexically above
+            this@Foo::x.isInitialized
+
+            // This is access to InnerSubclass.x which is inherited from Foo.x
+            this::x.isInitialized
+        }
+    }
+}
+
+fun onNonAccessible() {
+    Foo()::x.isInitialized
+}
+
+fun onNonLateinit() {
+    Foo()::nonLateInit.isInitialized
+}
+
+object Unrelated {
+    fun onNonAccessible() {
+        Foo()::x.isInitialized
+    }
+}
+
+class FooImpl : Foo() {
+    fun onNonAccessible() {
+        this::x.isInitialized
+    }
+}
+
+// FILE: other.kt
+
+class OtherFooImpl : Foo() {
+    fun onNonAccessible() {
+        this::x.isInitialized
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/multiplatform/jvmOverloads.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/multiplatform/jvmOverloads.fir.kt
new file mode 100644
index 00000000000..427d84be1c8
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/multiplatform/jvmOverloads.fir.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +MultiPlatformProjects
+// MODULE: m1-common
+// FILE: common.kt
+
+expect fun foo(x: String, y: Int = -1)
+
+// MODULE: m2-jvm(m1-common)
+// FILE: jvm.kt
+
+@JvmOverloads
+actual fun foo(x: String, y: Int) {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/abstract.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/abstract.fir.kt
new file mode 100644
index 00000000000..aaab812e231
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/abstract.fir.kt
@@ -0,0 +1,11 @@
+import kotlin.jvm.*
+
+abstract class C {
+    abstract external fun foo()
+}
+
+fun test() {
+    abstract class Local {
+        abstract external fun foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/body.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/body.fir.kt
new file mode 100644
index 00000000000..47810841b9e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/body.fir.kt
@@ -0,0 +1,25 @@
+import kotlin.jvm.*
+
+external fun foo() {}
+
+class C {
+    external fun foo() {}
+
+    companion object {
+        external fun foo() {}
+    }
+}
+
+object O {
+    external fun foo() {}
+}
+
+fun test() {
+    class Local {
+        external fun foo() {}
+    }
+
+    object {
+        external fun foo() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/constructor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/constructor.fir.kt
new file mode 100644
index 00000000000..3c11f664fd8
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/constructor.fir.kt
@@ -0,0 +1,10 @@
+class A {
+    external constructor() {}
+    inner class B {
+        external constructor() {}
+    }
+
+    external constructor(x: Int)
+}
+
+class C external constructor()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/inline.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/inline.fir.kt
new file mode 100644
index 00000000000..bc87beed226
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/inline.fir.kt
@@ -0,0 +1,11 @@
+import kotlin.jvm.*
+
+abstract class C {
+    inline external fun foo()
+}
+
+fun test() {
+    abstract class Local {
+        inline external fun foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/noBody.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/noBody.fir.kt
new file mode 100644
index 00000000000..3d262f82bb0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/noBody.fir.kt
@@ -0,0 +1,25 @@
+import kotlin.jvm.*
+
+external fun foo()
+
+class C {
+    external fun foo()
+
+    companion object {
+        external fun foo()
+    }
+}
+
+object O {
+    external fun foo()
+}
+
+fun test() {
+    class Local {
+        external fun foo()
+    }
+
+    object {
+        external fun foo()
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/nonFunction.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/nonFunction.fir.kt
new file mode 100644
index 00000000000..1755e7f8d60
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/nonFunction.fir.kt
@@ -0,0 +1,9 @@
+external class A
+
+external val foo: Int = 23
+
+class B {
+    external class A
+
+    external val foo: Int = 23
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/override.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/override.fir.kt
new file mode 100644
index 00000000000..7662d324aa0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/override.fir.kt
@@ -0,0 +1,9 @@
+import kotlin.jvm.*
+
+interface Base {
+    fun foo()
+}
+
+class Derived : Base {
+    override external fun foo()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/reified.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/reified.fir.kt
new file mode 100644
index 00000000000..1dd7ee2ac95
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/reified.fir.kt
@@ -0,0 +1,4 @@
+import kotlin.jvm.*
+
+external fun <reified T> foo()
+inline external fun <reified T> bar()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/native/trait.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/native/trait.fir.kt
new file mode 100644
index 00000000000..b05f86c1f69
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/native/trait.fir.kt
@@ -0,0 +1,11 @@
+import kotlin.jvm.*
+
+interface Tr {
+    external fun foo()
+    external fun bar() {}
+
+    companion object {
+        external fun foo()
+        external fun bar() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/outstar.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/outstar.fir.kt
new file mode 100644
index 00000000000..97dbf9f9e05
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/outstar.fir.kt
@@ -0,0 +1,11 @@
+// Reproduces exception in TypeResolver.kt: EA-66870
+
+import java.util.ArrayList
+
+abstract class J {
+    public abstract fun <T : Collection<S>, S : List<out *>> foo(x: T)
+    fun bar() {
+        val s = ArrayList<ArrayList<Int>>()
+        foo(s)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/overrideWithFunctionalType.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/overrideWithFunctionalType.fir.kt
new file mode 100644
index 00000000000..b00b584bd5e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/overrideWithFunctionalType.fir.kt
@@ -0,0 +1,17 @@
+// FILE: Derived.java
+import kotlin.jvm.functions.Function0;
+import org.jetbrains.annotations.NotNull;
+
+public class Derived implements Base {
+    @Override
+    public <V> void foo(@NotNull Function0<? extends V> compute) {}
+}
+
+// FILE: main.kt
+interface Base {
+    fun <V: Any> foo(compute: () -> V?)
+}
+
+fun main() {
+    Derived().foo<String> { "" }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/pureReifiable.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/pureReifiable.fir.kt
new file mode 100644
index 00000000000..648e86cbe34
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/pureReifiable.fir.kt
@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+inline fun <reified @kotlin.internal.PureReifiable T> foo(x: T) {}
+
+fun test() {
+    foo<List<String>>(listOf(""))
+    foo(listOf(""))
+
+    foo<Array<String>>(arrayOf(""))
+    foo(arrayOf(""))
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/pureReifiableArrayOperations.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/pureReifiableArrayOperations.fir.kt
new file mode 100644
index 00000000000..57cad51a93e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/pureReifiableArrayOperations.fir.kt
@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun test() {
+    arrayOf<List<String>>(listOf(""))
+    arrayOf(listOf(""))
+
+    arrayOf<Array<String>>(arrayOf(""))
+    arrayOf(arrayOf(""))
+
+    arrayOfNulls<Array<String>>(1)
+
+    Array<Array<String>>(1) { arrayOf("") }
+    Array(1) { arrayOf("") }
+    Array(1) { arrayOf("") }
+
+    emptyArray<Array<String>>()
+    val x: Array<Array<String>> = emptyArray()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/arrayList.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/arrayList.fir.kt
new file mode 100644
index 00000000000..b2f9ec43367
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/arrayList.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+import java.util.*
+
+fun bar(): String? = null
+
+fun foo() {
+    var x = ArrayList<String>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    x[0] = null
+    x[0] = bar()
+    x[0] = ""
+
+    val b1: MutableList<String?> = x
+    val b2: MutableList<String> = x
+    val b3: List<String?> = x
+
+    val b4: Collection<String?> = x
+    val b6: MutableCollection<String?> = x
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/arrayListNullable.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/arrayListNullable.fir.kt
new file mode 100644
index 00000000000..17cb82eb4c8
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/arrayListNullable.fir.kt
@@ -0,0 +1,23 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+import java.util.*
+
+fun bar(): String? = null
+
+fun foo() {
+    var x = ArrayList<String?>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    x[0] = null
+    x[0] = bar()
+    x[0] = ""
+
+    val b1: MutableList<String?> = x
+    val b2: MutableList<String> = x
+    val b3: List<String?> = x
+
+    val b4: Collection<String?> = x
+    val b6: MutableCollection<String?> = x
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableCollection.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableCollection.fir.kt
new file mode 100644
index 00000000000..5bedf9d6c26
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableCollection.fir.kt
@@ -0,0 +1,33 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// JAVAC_EXPECTED_FILE
+
+import java.util.*;
+
+// FILE: A.java
+@kotlin.jvm.PurelyImplements("kotlin.collections.MutableCollection")
+class A<T> extends AbstractCollection<T> {
+    @Override
+    public Iterator<T> iterator() {
+        return null;
+    }
+
+    @Override
+    public int size() {
+        return 0;
+    }
+}
+
+// FILE: b.kt
+
+fun bar(): String? = null
+
+fun foo() {
+    var x = A<String>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    val b1: Collection<String?> = x
+    val b2: MutableCollection<String?> = x
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableList.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableList.fir.kt
new file mode 100644
index 00000000000..6a4b798bea1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableList.fir.kt
@@ -0,0 +1,41 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// JAVAC_EXPECTED_FILE
+
+import java.util.*;
+
+// FILE: A.java
+@kotlin.jvm.PurelyImplements("kotlin.collections.MutableList")
+class A<T> extends AbstractList<T> {
+    @Override
+    public T get(int index) {
+        return null;
+    }
+
+    @Override
+    public int size() {
+        return 0;
+    }
+}
+
+// FILE: b.kt
+
+fun bar(): String? = null
+
+fun foo() {
+    var x = A<String>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    x[0] = null
+    x[0] = bar()
+    x[0] = ""
+
+    val b1: MutableList<String?> = x
+    val b2: MutableList<String> = x
+    val b3: List<String?> = x
+
+    val b4: Collection<String?> = x
+    val b6: MutableCollection<String?> = x
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/invalidFqName.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/invalidFqName.fir.kt
new file mode 100644
index 00000000000..80c8397edc9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/invalidFqName.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// JAVAC_EXPECTED_FILE
+
+// FILE: A.java
+import java.util.*;
+
+@kotlin.jvm.PurelyImplements("")
+public class A<T> extends AbstractList<T> {
+    @Override
+    public T get(int index) {
+        return null;
+    }
+
+    @Override
+    public int size() {
+        return 0;
+    }
+}
+
+// FILE: B.java
+import java.util.*;
+
+@kotlin.jvm.PurelyImplements("[INVALID]")
+public class B<T> extends AbstractList<T> {}
+
+// FILE: main.kt
+val x = A<String>()
+val y = B<String>()
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/maps.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/maps.fir.kt
new file mode 100644
index 00000000000..26697f2a424
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/maps.fir.kt
@@ -0,0 +1,81 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+import java.util.*
+import java.util.concurrent.*
+
+fun bar(): String? = null
+val nullableInt: Int? = null
+
+fun hashMapTest() {
+    var x: HashMap<String, Int> = HashMap<String, Int>()
+    x.put(null, null)
+    x.put("", null)
+    x.put(bar(), 1)
+    x.put("", 1)
+
+    x[null] = 1
+    x[bar()] = 1
+    x[""] = nullableInt
+    x[""] = 1
+
+    val b1: MutableMap<String, Int?> = x
+    val b2: MutableMap<String, Int> = x
+    val b3: Map<String?, Int> = x
+    val b4: Map<String?, Int?> = x
+    val b5: Map<String, Int?> = x
+
+    val b6: Int = x[""]
+    val b7: Int = x.get("")
+
+    val b8: Int? = x.get("")
+}
+
+fun treeMapTest() {
+    var x: TreeMap<String, Int> = TreeMap<String, Int>()
+    x.put(null, null)
+    x.put("", null)
+    x.put(bar(), 1)
+    x.put("", 1)
+
+    x[null] = 1
+    x[bar()] = 1
+    x[""] = nullableInt
+    x[""] = 1
+
+    val b1: MutableMap<String, Int?> = x
+    val b2: MutableMap<String, Int> = x
+    val b3: Map<String?, Int> = x
+    val b4: Map<String?, Int?> = x
+    val b5: Map<String, Int?> = x
+
+    val b6: Int = x[""]
+    val b7: Int = x.get("")
+
+    val b8: Int? = x.get("")
+}
+
+fun concurrentHashMapTest() {
+    var x: ConcurrentHashMap<String, Int> = ConcurrentHashMap<String, Int>()
+    x.put(null, null)
+    x.put("", null)
+    x.put(bar(), 1)
+    x.put("", 1)
+
+    x[null] = 1
+    x[bar()] = 1
+    x[""] = nullableInt
+    x[""] = 1
+
+    val b1: MutableMap<String, Int?> = x
+    val b2: MutableMap<String, Int> = x
+    val b3: Map<String?, Int> = x
+    val b4: Map<String?, Int?> = x
+    val b5: Map<String, Int?> = x
+
+    val b6: Int = x[""]
+    val b7: Int = x.get("")
+
+    val b8: Int? = x.get("")
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/mapsWithNullableKey.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/mapsWithNullableKey.fir.kt
new file mode 100644
index 00000000000..d139896edca
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/mapsWithNullableKey.fir.kt
@@ -0,0 +1,57 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+import java.util.*
+
+fun bar(): String? = null
+val nullableInt: Int? = null
+
+fun hashMapTest() {
+    var x: HashMap<String?, Int> = HashMap<String?, Int>()
+    x.put(null, null)
+    x.put("", null)
+    x.put(bar(), 1)
+    x.put("", 1)
+
+    x[null] = 1
+    x[bar()] = 1
+    x[""] = nullableInt
+    x[""] = 1
+
+    val b1: MutableMap<String?, Int?> = x
+    val b2: MutableMap<String?, Int> = x
+    val b3: Map<String?, Int> = x
+    val b4: Map<String?, Int?> = x
+    val b5: Map<String, Int?> = x
+
+    val b6: Int = x[""]
+    val b7: Int = x[null]
+    val b8: Int = x.get("")
+
+    val b9: Int? = x.get("")
+}
+
+fun treeMapTest() {
+    var x: TreeMap<String?, Int> = TreeMap<String?, Int>()
+    x.put(null, null)
+    x.put("", null)
+    x.put(bar(), 1)
+    x.put("", 1)
+
+    x[null] = 1
+    x[bar()] = 1
+    x[""] = nullableInt
+    x[""] = 1
+
+    val b1: MutableMap<String?, Int?> = x
+    val b2: MutableMap<String?, Int> = x
+    val b3: Map<String?, Int> = x
+    val b4: Map<String?, Int?> = x
+    val b5: Map<String, Int?> = x
+
+    val b6: Int = x[""]
+    val b7: Int = x.get("")
+
+    val b8: Int? = x.get("")
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/mapsWithNullableValues.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/mapsWithNullableValues.fir.kt
new file mode 100644
index 00000000000..f06efd6038e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/mapsWithNullableValues.fir.kt
@@ -0,0 +1,56 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+import java.util.*
+
+fun bar(): String? = null
+val nullableInt: Int? = null
+
+fun hashMapTest() {
+    var x: HashMap<String, Int?> = HashMap<String, Int?>()
+    x.put(null, null)
+    x.put("", null)
+    x.put(bar(), 1)
+    x.put("", 1)
+
+    x[null] = 1
+    x[bar()] = 1
+    x[""] = nullableInt
+    x[""] = 1
+
+    val b1: MutableMap<String, Int> = x
+    val b2: MutableMap<String, Int?> = x
+    val b3: Map<String, Int> = x
+    val b4: Map<String, Int?> = x
+    val b5: Map<String?, Int?> = x
+
+    val b6: Int = x[""]
+    val b7: Int = x.get("")
+
+    val b8: Int? = x.get("")
+}
+
+fun treeMapTest() {
+    var x: TreeMap<String, Int?> = TreeMap<String, Int?>()
+    x.put(null, null)
+    x.put("", null)
+    x.put(bar(), 1)
+    x.put("", 1)
+
+    x[null] = 1
+    x[bar()] = 1
+    x[""] = nullableInt
+    x[""] = 1
+
+    val b1: MutableMap<String, Int> = x
+    val b2: MutableMap<String, Int?> = x
+    val b3: Map<String, Int> = x
+    val b4: Map<String, Int?> = x
+    val b5: Map<String?, Int?> = x
+
+    val b6: Int = x[""]
+    val b7: Int = x.get("")
+
+    val b8: Int? = x.get("")
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/sets.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/sets.fir.kt
new file mode 100644
index 00000000000..b50262fefeb
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/sets.fir.kt
@@ -0,0 +1,49 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+import java.util.*
+
+fun bar(): String? = null
+
+fun fooHashSet() {
+    var x = HashSet<String>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    val b1: MutableSet<String?> = x
+    val b2: MutableSet<String> = x
+    val b3: Set<String?> = x
+
+    val b4: Collection<String?> = x
+    val b6: MutableCollection<String?> = x
+}
+
+fun fooTreeSet() {
+    var x = TreeSet<String>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    val b1: MutableSet<String?> = x
+    val b2: MutableSet<String> = x
+    val b3: Set<String?> = x
+
+    val b4: Collection<String?> = x
+    val b6: MutableCollection<String?> = x
+}
+
+fun fooLinkedHashSet() {
+    var x = LinkedHashSet<String>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    val b1: MutableSet<String?> = x
+    val b2: MutableSet<String> = x
+    val b3: Set<String?> = x
+
+    val b4: Collection<String?> = x
+    val b6: MutableCollection<String?> = x
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/wrongTypeParametersCount.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/wrongTypeParametersCount.fir.kt
new file mode 100644
index 00000000000..1fb450aad86
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/wrongTypeParametersCount.fir.kt
@@ -0,0 +1,40 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// JAVAC_EXPECTED_FILE
+
+import java.util.*;
+
+// FILE: A.java
+@kotlin.jvm.PurelyImplements("kotlin.collections.MutableList")
+class A<T, V> extends AbstractList<T> {
+    @Override
+    public T get(int index) {
+        return null;
+    }
+
+    @Override
+    public int size() {
+        return 0;
+    }
+}
+
+// FILE: b.kt
+
+fun bar(): String? = null
+
+fun foo() {
+    var x = A<String, String>()
+    x.add(null)
+    x.add(bar())
+    x.add("")
+
+    x[0] = null
+    x[0] = bar()
+    x[0] = ""
+
+    val b1: MutableList<String?> = x
+    val b2: MutableList<String> = x
+    val b3: List<String?> = x
+
+    val b4: Collection<String?> = x
+    val b6: MutableCollection<String?> = x
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/reflection/typeOfWithNonReifiedParameter.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/reflection/typeOfWithNonReifiedParameter.fir.kt
new file mode 100644
index 00000000000..2f910a1e162
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/reflection/typeOfWithNonReifiedParameter.fir.kt
@@ -0,0 +1,35 @@
+// !USE_EXPERIMENTAL: kotlin.ExperimentalStdlibApi
+// !LANGUAGE: +ProhibitNonReifiedArraysAsReifiedTypeArguments
+
+import kotlin.reflect.typeOf
+
+inline fun <X, reified Y, Z : Y> test1() {
+    typeOf<X>()
+    typeOf<List<X>>()
+    typeOf<Array<X?>>()
+
+    typeOf<Y>()
+
+    typeOf<Z>()
+    typeOf<List<Z>?>()
+    typeOf<Array<Z>>()
+}
+
+
+class Test2<W> {
+    fun test2() {
+        typeOf<W>()
+        typeOf<List<W?>>()
+        typeOf<Array<W>>()
+    }
+}
+
+
+inline fun <reified U> f() {
+    typeOf<U>()
+}
+
+fun <T> test3() {
+    // We don't report anything here because we can't know in frontend how the corresponding type parameter is used in f
+    f<List<T>>()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/ea63992.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/ea63992.fir.kt
new file mode 100644
index 00000000000..6fdd50da1ad
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/ea63992.fir.kt
@@ -0,0 +1,7 @@
+fun add(a: Int, b: Int) = a + b
+interface A {
+    fun <T> shuffle(x: List<T>): List<T>
+    fun <T> foo(f : (List<T>) -> List<T>, x : List<T>)
+
+fun f() : (Int, Int) -> Int = ::add
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/ea65206.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/ea65206.fir.kt
new file mode 100644
index 00000000000..09dbc59c925
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/ea65206.fir.kt
@@ -0,0 +1,9 @@
+class A {
+    val x = arrayListOf<(A<<!SYNTAX!><!>>) -> Unit>()
+
+    // Here we got an exception during type comparison
+    fun foo(){
+        x.add {}
+    }
+
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/ea66827_dataClassWrongToString.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/ea66827_dataClassWrongToString.fir.kt
new file mode 100644
index 00000000000..9cc1a6bf83d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/ea66827_dataClassWrongToString.fir.kt
@@ -0,0 +1,7 @@
+data class A(val x: Int) {
+    fun toArray(): IntArray =
+            intArrayOf(x)
+
+    override fun toString() =
+            toArray().takeWhile { it != -1 } // .joinToString()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/ea70485_functionTypeInheritor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/ea70485_functionTypeInheritor.fir.kt
new file mode 100644
index 00000000000..b94f4ee0b6a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/ea70485_functionTypeInheritor.fir.kt
@@ -0,0 +1,17 @@
+class O : Function2<Int, String, Unit> {
+    override fun invoke(p1: Int, p2: String) {
+    }
+}
+
+fun test() {
+    val a = fun(o: O) {
+    }
+    <!INAPPLICABLE_CANDIDATE!>a<!> {}
+}
+
+class Ext : String.() -> Unit {
+}
+
+fun test2() {
+    val f: Ext = {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/ea70880_illegalJvmName.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/ea70880_illegalJvmName.fir.kt
new file mode 100644
index 00000000000..c1ce1e4d6b1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/ea70880_illegalJvmName.fir.kt
@@ -0,0 +1,8 @@
+@JvmName()
+fun foo() {}
+
+@JvmName(42)
+fun bar() {}
+
+@JvmName("a", "b")
+fun baz() {}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/kt10001.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/kt10001.fir.kt
new file mode 100644
index 00000000000..1f2bc054fdf
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/kt10001.fir.kt
@@ -0,0 +1,9 @@
+fun foo1(p: Pair<Int?, Int>): Int {
+    if (p.first != null) return p.first!!
+    return p.second
+}
+
+fun foo2(p: Pair<Int?, Int>): Int {
+    if (p.first != null) return p.first
+    return p.second
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/kt2082.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/kt2082.fir.kt
new file mode 100644
index 00000000000..0548489ea06
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/kt2082.fir.kt
@@ -0,0 +1,10 @@
+fun foo(c : Collection<String>) = {
+    c.filter{
+        val s : String? = bar()
+        if (s == null) false // here!
+        zoo(s)
+    }
+}
+
+fun bar() : String? = null
+fun zoo(s : String) : Boolean = true
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/kt26806.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/kt26806.fir.kt
new file mode 100644
index 00000000000..5ab2c2ff4bc
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/kt26806.fir.kt
@@ -0,0 +1,9 @@
+const val myPi = kotlin.math.PI
+
+annotation class Anno(val d: Double)
+
+@Anno(kotlin.math.PI)
+fun f() {}
+
+@Anno(myPi)
+fun g() {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/kt34391.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/kt34391.fir.kt
new file mode 100644
index 00000000000..63db720eb0d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/kt34391.fir.kt
@@ -0,0 +1,19 @@
+// !LANGUAGE: +NewInference
+
+fun main() {
+    val list = listOf(A())
+    list.forEach(A::foo)
+    list.forEach {
+        it.foo()
+    }
+}
+
+class A {
+    @ExperimentalTime
+    fun foo() {
+        println("a")
+    }
+}
+
+@Experimental(level = Experimental.Level.ERROR)
+annotation class ExperimentalTime
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/kt9345.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/kt9345.fir.kt
new file mode 100644
index 00000000000..5e21e489ac9
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/kt9345.fir.kt
@@ -0,0 +1,3 @@
+//KT-9345 Type inference failure
+
+fun Class<*>.foo(): Any? = kotlin.<!UNRESOLVED_REFERENCE!>objectInstance<!>
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/regression/kt9820_javaFunctionTypeInheritor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/regression/kt9820_javaFunctionTypeInheritor.fir.kt
new file mode 100644
index 00000000000..a5feb405213
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/regression/kt9820_javaFunctionTypeInheritor.fir.kt
@@ -0,0 +1,16 @@
+// FILE: J.java
+
+import kotlin.jvm.functions.Function1;
+
+public interface J extends Function1<Integer, Void> {
+}
+
+// FILE: 1.kt
+
+fun useJ(j: J) {
+    j(42)
+}
+
+fun jj() {
+    useJ({})
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/reified/arrayConstruction.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/reified/arrayConstruction.fir.kt
new file mode 100644
index 00000000000..fba40c1657f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/reified/arrayConstruction.fir.kt
@@ -0,0 +1,18 @@
+// !WITH_NEW_INFERENCE
+
+fun <T> fail1(): Array<T> = Array(1) { null!! }
+fun <T> ok1(block: () -> Array<T>): Array<T> = block()
+inline fun <reified T> ok2(): Array<T> = Array(1) { null!! }
+
+
+fun <T> fail2(): Array<T> = ok1 { Array<T>(1) {  null!! } }
+fun <T> ok3(block: () -> Array<T>): Array<T> = ok1 { block() }
+inline fun <reified T> ok4(): Array<T> = ok1 { Array<T>(1) { null!! } }
+
+fun <T> fail3(block: () -> T): Pair<Array<T>, Array<T>> = Pair(arrayOf(
+        block()), arrayOf()
+)
+inline fun <reified T> ok5(block: () -> T): Pair<Array<T>, Array<T>> = Pair(
+        arrayOf(block()), arrayOf()
+)
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/reified/arrayOfNullsReified.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/reified/arrayOfNullsReified.fir.kt
new file mode 100644
index 00000000000..e418e602769
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/reified/arrayOfNullsReified.fir.kt
@@ -0,0 +1,14 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun <T> foo() {
+    val x = arrayOfNulls<T>(5)
+}
+
+inline fun <reified T> bar() {
+    val x = arrayOfNulls<T>(5)
+}
+
+fun baz() {
+    bar<Int>()
+    val x: Array<Int?> = arrayOfNulls(5)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/reified/kt11881.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/reified/kt11881.fir.kt
new file mode 100644
index 00000000000..77fe0056f6a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/reified/kt11881.fir.kt
@@ -0,0 +1,9 @@
+class Inv<T>
+
+inline operator fun <reified T> Inv<T>.invoke() {}
+
+operator fun <K> Inv<K>.get(i: Int): Inv<K> = this
+
+fun <K> test(a: Inv<K>) {
+    a[1]()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/reified/nonCallableReiefied.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/reified/nonCallableReiefied.fir.kt
new file mode 100644
index 00000000000..df17f0fad3e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/reified/nonCallableReiefied.fir.kt
@@ -0,0 +1,11 @@
+class A<T>(val x: Array<T>) {
+    val y: Int = x[0].toString().length
+
+    fun foo(a: T) {
+        x[0] = a
+    }
+
+    fun <R> bar(a: Array<R>): Int = a[0].toString().length
+}
+
+fun <T> baz(a: Array<T>): String = a[0].toString()
diff --git a/compiler/testData/diagnostics/testsWithStdLib/reified/reifiedNothingSubstitution.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/reified/reifiedNothingSubstitution.fir.kt
new file mode 100644
index 00000000000..988bf2ee966
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/reified/reifiedNothingSubstitution.fir.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNREACHABLE_CODE -UNUSED_VARIABLE -DEPRECATION
+// !WITH_NEW_INFERENCE
+
+inline fun<reified T> foo(block: () -> T): String = block().toString()
+
+inline fun <reified T: Any> javaClass(): Class<T> = <!OTHER_ERROR!>T<!>::class.<!INAPPLICABLE_CANDIDATE!>java<!>
+
+fun box() {
+    val a = arrayOf(null!!)
+    val b = Array<Nothing?>(5) { null!! }
+    val c = foo() { null!! }
+    val d = foo<Any> { null!! }
+    val e = foo { "1" as Nothing }
+    val e1 = foo { "1" as Nothing? }
+
+    val f = javaClass<Nothing>()
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/hidesMembers.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/hidesMembers.fir.kt
new file mode 100644
index 00000000000..db29f51110a
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/hidesMembers.fir.kt
@@ -0,0 +1,52 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+// FILE: 2.kt
+package b
+
+import a.A
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.internal.HidesMembers
+fun A.forEach(i: Int) = i
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.internal.HidesMembers
+fun A.forEach(s: String) {}
+
+
+// FILE: 1.kt
+package a
+
+import b.*
+
+class A {
+    fun forEach() = this
+    fun forEach(i: Int) = this
+    fun forEach(i: String) = this
+}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.internal.HidesMembers
+fun A.forEach() = ""
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.internal.HidesMembers
+fun A.forEach(s: String) {}
+
+fun test(a: A) {
+    a.forEach() checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+
+    a.forEach(1) checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    a.forEach("")
+
+    with(a) {
+        forEach() checkType { _<String>() }
+
+        forEach(1) checkType { _<Int>() }
+
+        forEach("")
+    }
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/hidesMembers2.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/hidesMembers2.fir.kt
new file mode 100644
index 00000000000..6d0bf09ce25
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/hidesMembers2.fir.kt
@@ -0,0 +1,42 @@
+// !CHECK_TYPE
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_PARAMETER -UNUSED_VARIABLE
+class A {
+    fun forEach() = this
+    fun forEach(i: Int) = this
+}
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.internal.HidesMembers
+fun A.forEach(i: Int) = i
+
+class B {
+    @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+    @kotlin.internal.HidesMembers
+    fun A.forEach() = this@B
+
+    fun test(a: A) {
+        a.forEach() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><A>() } // todo
+
+        with(a) {
+            forEach() checkType { _<A>() } // todo
+        }
+    }
+}
+
+fun test2(a: A) {
+    @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+    @kotlin.internal.HidesMembers
+    fun A.forEach() = ""
+
+    @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+    @kotlin.internal.HidesMembers
+    fun A.forEach(i: Int) = ""
+
+    a.forEach() checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    a.forEach(1)
+
+    with(a) {
+        forEach() checkType { <!INAPPLICABLE_CANDIDATE!>_<!><String>() }
+        forEach(1)
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/javaPackageMembers.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/javaPackageMembers.fir.kt
new file mode 100644
index 00000000000..16749b92a94
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/javaPackageMembers.fir.kt
@@ -0,0 +1,9 @@
+fun fn(): Nothing = throw java.lang.<!UNRESOLVED_REFERENCE!>RuntimeException<!>("oops")
+
+val x: Nothing = throw java.lang.<!UNRESOLVED_REFERENCE!>RuntimeException<!>("oops")
+
+class SomeClass {
+    fun method() {
+        throw java.lang.<!UNRESOLVED_REFERENCE!>AssertionError<!>("!!!")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/javaStaticMembers.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/javaStaticMembers.fir.kt
new file mode 100644
index 00000000000..56b7c6ab3f2
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/javaStaticMembers.fir.kt
@@ -0,0 +1,12 @@
+// FILE: Test.java
+public class Test {
+    public static final String FOO = "test";
+}
+
+// FILE: test.kt
+fun ff() {
+    val a = Test.FOO
+    val b = Test?.FOO
+    System.out.println(a + b)
+    System?.out.println(a + b)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/kt10103.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/kt10103.fir.kt
new file mode 100644
index 00000000000..986bf3b6bae
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/kt10103.fir.kt
@@ -0,0 +1 @@
+val stringReversed = String::reversed
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/kt10732a.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/kt10732a.fir.kt
new file mode 100644
index 00000000000..f7ac21f1f61
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/kt10732a.fir.kt
@@ -0,0 +1,10 @@
+fun <T1> List<T1>?.foo() {}
+
+@JvmName("foo1")
+fun <T2> List<T2>.foo() {}
+
+
+fun <T1> bar(x: List<T1>) = x
+
+@JvmName("bar1")
+fun <T2> bar(x: List<T2>?) = x
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/kt4711.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/kt4711.fir.kt
new file mode 100644
index 00000000000..3c7c16d90e8
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/kt4711.fir.kt
@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+//KT-4711 Error type with no error reported from type inference
+
+fun main() {
+    val n = 100
+    val delta = 1.0 / n
+    val startTimeNanos = System.nanoTime()
+
+    // the problem sits on the next line:
+    val pi = 4.0.toDouble() * delta * (1..n).reduce(
+            {t, i ->
+                val x = (i - 0.5) * delta
+                t + 1.0 / (1.0 + x * x)
+
+            })
+    // !!! pi has error type here
+
+    val elapseTime = (System.nanoTime() - startTimeNanos) / 1e9
+
+    println("pi_sequential_reduce $pi $n $elapseTime")
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/samAgainstFunctionalType.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/samAgainstFunctionalType.fir.kt
new file mode 100644
index 00000000000..16c870e7f15
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/samAgainstFunctionalType.fir.kt
@@ -0,0 +1,30 @@
+// !WITH_NEW_INFERENCE
+// !CHECK_TYPE
+
+// FILE: StaticOverrides.java
+
+import kotlin.Unit;
+import kotlin.jvm.functions.Function0;
+
+public class StaticOverrides {
+    public static class A {
+        public static int foo(Runnable x) { return 0; }
+        public static boolean foo(Function0<Unit> x) { return true; }
+    }
+
+    public static class B {
+        public static String foo(Runnable x) { return ""; }
+    }
+
+    public static class C extends A {
+        public static String foo(Runnable x) { return ""; }
+    }
+}
+
+// FILE: test.kt
+
+fun test() {
+    StaticOverrides.A.<!AMBIGUITY!>foo<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Boolean>() }
+    StaticOverrides.B.foo {} checkType { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+    StaticOverrides.C.<!AMBIGUITY!>foo<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Boolean>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/samConstructorVsFun.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/samConstructorVsFun.fir.kt
new file mode 100644
index 00000000000..57eb8e96916
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/samConstructorVsFun.fir.kt
@@ -0,0 +1,30 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+// FILE: s/SamConstructor.java
+package s;
+
+public class SamConstructor {
+    public SamConstructor(Runnable r) {
+    }
+
+    public static void foo(Runnable r) {}
+}
+
+// FILE: 1.kt
+package a
+
+fun SamConstructor(a: () -> Unit) {}
+
+// FILE: 2.kt
+
+package b
+
+import s.SamConstructor
+import a.*
+
+fun test() {
+    val a: s.SamConstructor = SamConstructor {  }
+
+    val b: s.SamConstructor = SamConstructor(null)
+
+    SamConstructor.foo(null)
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenerics.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenerics.fir.kt
new file mode 100644
index 00000000000..68cd3929737
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenerics.fir.kt
@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// !WITH_NEW_INFERENCE
+
+// FILE: Foo.java
+import kotlin.Unit;
+import kotlin.jvm.functions.Function1;
+
+class Foo {
+    interface FObject<T> {
+        void invoke(T i);
+    }
+
+    public String foo(FObject<Integer> f) { return ""; }
+    public int foo(Function1<Integer, Unit> f) { return 1; }
+
+    public String bar(FObject<Object> f) { return ""; }
+    public int bar(Function1<Integer, Unit> f) { return 1; }
+}
+
+// FILE: 1.kt
+fun test() {
+    Foo().<!AMBIGUITY!>foo<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    Foo().<!AMBIGUITY!>bar<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenericsWithoutRefinedSams.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenericsWithoutRefinedSams.fir.kt
new file mode 100644
index 00000000000..39ea5223af3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithGenericsWithoutRefinedSams.fir.kt
@@ -0,0 +1,26 @@
+// !LANGUAGE: -RefinedSamAdaptersPriority
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// !WITH_NEW_INFERENCE
+
+// FILE: Foo.java
+import kotlin.Unit;
+import kotlin.jvm.functions.Function1;
+
+class Foo {
+    interface FObject<T> {
+        void invoke(T i);
+    }
+
+    public String foo(FObject<Integer> f) { return ""; }
+    public int foo(Function1<Integer, Unit> f) { return 1; }
+
+    public String bar(FObject<Object> f) { return ""; }
+    public int bar(Function1<Integer, Unit> f) { return 1; }
+}
+
+// FILE: 1.kt
+fun test() {
+    Foo().<!AMBIGUITY!>foo<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+    Foo().<!AMBIGUITY!>bar<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunction.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunction.fir.kt
new file mode 100644
index 00000000000..394b4ee42b7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunction.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+
+// FILE: Foo.java
+import kotlin.Unit;
+import kotlin.jvm.functions.Function1;
+
+public class Foo {
+    interface FObject {
+        void invoke(Object i);
+    }
+
+    public String test(FObject f) { return ""; }
+    public int test(Function1<Integer, Unit> f) { return 1; }
+}
+
+// FILE: 1.kt
+fun bar() {
+    Foo().<!AMBIGUITY!>test<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><String>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunctionWithoutRefinedSams.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunctionWithoutRefinedSams.fir.kt
new file mode 100644
index 00000000000..db8e64fa963
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/resolve/samOverloadsWithKtFunctionWithoutRefinedSams.fir.kt
@@ -0,0 +1,22 @@
+// !LANGUAGE: -RefinedSamAdaptersPriority
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// !CHECK_TYPE
+// !WITH_NEW_INFERENCE
+
+// FILE: Foo.java
+import kotlin.Unit;
+import kotlin.jvm.functions.Function1;
+
+public class Foo {
+    interface FObject {
+        void invoke(Object i);
+    }
+
+    public String test(FObject f) { return ""; }
+    public int test(Function1<Integer, Unit> f) { return 1; }
+}
+
+// FILE: 1.kt
+fun bar() {
+    Foo().<!AMBIGUITY!>test<!> {} <!INAPPLICABLE_CANDIDATE!>checkType<!> { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/shadowingInDestructuring.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/shadowingInDestructuring.fir.kt
new file mode 100644
index 00000000000..51e32baee57
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/shadowingInDestructuring.fir.kt
@@ -0,0 +1,10 @@
+data class XY(val x: Int, val y: Int)
+
+fun foo(list: List<XY>) {
+    for ((x1, y1) in list) {
+        for ((x2, y2) in list) {
+            if (x1 == y2 && x2 == y1) return
+        }
+        list.map { (x3, y3) -> x3 + y3 }
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachSafe.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachSafe.fir.kt
new file mode 100644
index 00000000000..3eb045d61d2
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachSafe.fir.kt
@@ -0,0 +1,12 @@
+// !WITH_NEW_INFERENCE
+// KT-7186: False "Type mismatch" error
+
+fun indexOfMax(a: IntArray): Int? {
+    var maxI: Int? = null
+    a.forEachIndexed { i, value ->
+        if (maxI == null || value >= a[maxI]) {
+            maxI = i
+        }
+    }
+    return maxI
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachUnsafe.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachUnsafe.fir.kt
new file mode 100644
index 00000000000..2972e263e69
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/forEachUnsafe.fir.kt
@@ -0,0 +1,14 @@
+// KT-7186: False "Type mismatch" error
+
+fun indexOfMax(a: IntArray): Int? {
+    var maxI: Int? = 0
+    a.forEachIndexed { i, value ->
+        if (value >= a[maxI]) {
+            maxI = i
+        }
+        else if (value < 0) {
+            maxI = null
+        }
+    }
+    return maxI
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/kt10463.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/kt10463.fir.kt
new file mode 100644
index 00000000000..dcaeb8aa146
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/kt10463.fir.kt
@@ -0,0 +1,6 @@
+val test: Int = listOf<Any>().map {
+    when (it) {
+        is Int -> it
+        else -> throw AssertionError()
+    }
+}.sum()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/lazyDeclaresAndModifies.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/lazyDeclaresAndModifies.fir.kt
new file mode 100644
index 00000000000..7536bd51c83
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/lazyDeclaresAndModifies.fir.kt
@@ -0,0 +1,11 @@
+class My(val x: Int?) {
+    val y: Int? by lazy {
+        var z = x
+        while (z != null) {
+            z = z.hashCode()
+            if (z < 0) return@lazy z
+            if (z == 0) z = null
+        }
+        return@lazy null
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letAlwaysChangesToNotNull.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letAlwaysChangesToNotNull.fir.kt
new file mode 100644
index 00000000000..3fa4b2468ec
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letAlwaysChangesToNotNull.fir.kt
@@ -0,0 +1,7 @@
+// KT-9051: Allow smart cast for captured variables if they are not modified
+
+fun foo(y: String) {
+    var x: String? = null
+    y.let { x = it }
+    x.length // Smart cast is not possible
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNotNull.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNotNull.fir.kt
new file mode 100644
index 00000000000..529c3172b29
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNotNull.fir.kt
@@ -0,0 +1,7 @@
+// KT-9051: Allow smart cast for captured variables if they are not modified
+
+fun foo(y: String?) {
+    var x: String? = null
+    y?.let { x = it }
+    x.<!INAPPLICABLE_CANDIDATE!>length<!> // Smart cast is not possible
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNull.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNull.fir.kt
new file mode 100644
index 00000000000..06db53d4e93
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNull.fir.kt
@@ -0,0 +1,9 @@
+// KT-9051: Allow smart cast for captured variables if they are not modified
+
+fun foo(y: String?) {
+    var x: String? = ""
+    if (x != null) {
+        y?.let { x = null }
+        x.length // Smart cast is not possible
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNullComplex.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNullComplex.fir.kt
new file mode 100644
index 00000000000..ddee7e5b9df
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letChangesToNullComplex.fir.kt
@@ -0,0 +1,11 @@
+// KT-9051: Allow smart cast for captured variables if they are not modified
+
+fun bar(z: String?) = z
+
+fun foo(y: String?) {
+    var x: String? = ""
+    if (x != null) {
+        bar(y?.let { x = null; it }).<!INAPPLICABLE_CANDIDATE!>length<!>
+        x.length // Smart cast is not possible
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letMergeNotNull.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letMergeNotNull.fir.kt
new file mode 100644
index 00000000000..833bb2fecce
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letMergeNotNull.fir.kt
@@ -0,0 +1,9 @@
+// KT-9051: Allow smart cast for captured variables if they are not modified
+
+fun foo(y: String?) {
+    var x: String? = null
+    if (x != null) {
+        y?.let { x = it }
+        x.length // not-null or not-null
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letStable.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letStable.fir.kt
new file mode 100644
index 00000000000..fe36fbf9f68
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letStable.fir.kt
@@ -0,0 +1,10 @@
+// KT-9051: Allow smart cast for captured variables if they are not modified
+
+fun foo(y: String?) {
+    var x: String? = ""
+    if (x != null) {
+        y?.let { x != y }
+        // x is not changed, smart cast is possible
+        x.length
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letUsesOwnReceiver.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letUsesOwnReceiver.fir.kt
new file mode 100644
index 00000000000..0e3733de8c6
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/letUsesOwnReceiver.fir.kt
@@ -0,0 +1,7 @@
+// Based on KT-9033
+fun f(s: String) = s
+
+fun foo(s: String?) {
+    s?.let { f(s) }
+    s?.let { f(it) }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/listOfGeneric.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/listOfGeneric.fir.kt
new file mode 100644
index 00000000000..f9611264f24
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/listOfGeneric.fir.kt
@@ -0,0 +1,8 @@
+// See KT-9529 Smart cast causes code to be incompilable
+
+fun <T : Any> foo(o: T): Collection<T> {
+    if (o is String) {
+        return listOf(o)
+    }
+    return listOf(o)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/smartcasts/withChangesToNull.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/withChangesToNull.fir.kt
new file mode 100644
index 00000000000..56035143ab2
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/smartcasts/withChangesToNull.fir.kt
@@ -0,0 +1,10 @@
+fun foo(y: String?) {
+    var x: String? = ""
+    if (x != null) {
+        with(y?.let { x = null; it }) {
+            this.length
+            x.length
+        }
+        x.length
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/sourceCompatibility/noDefaultImportOfKotlinComparisons.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/sourceCompatibility/noDefaultImportOfKotlinComparisons.fir.kt
new file mode 100644
index 00000000000..17bb9e1fbab
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/sourceCompatibility/noDefaultImportOfKotlinComparisons.fir.kt
@@ -0,0 +1,3 @@
+// !LANGUAGE: -DefaultImportOfPackageKotlinComparisons
+
+fun foo() = compareBy<String> { it.length }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/streams.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/streams.fir.kt
new file mode 100644
index 00000000000..a447b3bba69
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/streams.fir.kt
@@ -0,0 +1,9 @@
+// FULL_JDK
+// STDLIB_JDK8
+
+import java.util.*
+import kotlin.streams.toList
+
+fun testStreams(list: ArrayList<String>) {
+    list.stream().toList()
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/blackListed.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/blackListed.fir.kt
new file mode 100644
index 00000000000..cb006fee726
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/blackListed.fir.kt
@@ -0,0 +1,22 @@
+// !WITH_NEW_INFERENCE
+// FULL_JDK
+
+abstract class A : MutableList<String> {
+    override fun sort(/*0*/ p0: java.util.Comparator<in String>) {
+        super.sort(p0)
+    }
+}
+
+fun foo(x: MutableList<String>, y: java.util.ArrayList<String>, z: A, p: java.util.Comparator<in String>) {
+    x.sort(p)
+    y.sort(p)
+
+    z.sort(p)
+}
+
+fun bar(x: MutableList<String>, y: java.util.ArrayList<String>, z: A) {
+    x.sort { a, b -> a.length - b.length }
+    y.sort { a, b -> a.length - b.length }
+
+    z.sort { a, b -> a.length - b.length }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/unsupportedFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/unsupportedFeature.fir.kt
new file mode 100644
index 00000000000..5839abbd937
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/targetedBuiltIns/unsupportedFeature.fir.kt
@@ -0,0 +1,66 @@
+// !CHECK_TYPE
+// !LANGUAGE: -AdditionalBuiltInsMembers
+// !WITH_NEW_INFERENCE
+// SKIP_TXT
+// FULL_JDK
+
+class A : java.util.ArrayList<String>() {
+    // `stream` is defined in ArrayList, so it was impossible to override it in 1.0
+    override fun stream(): java.util.stream.Stream<String> = super.stream()
+
+    // `sort` is defined in ArrayList, so it was possible to override it in 1.0
+    override fun sort(c: Comparator<in String>?) {
+        super.sort(c)
+    }
+}
+
+class A1 : java.util.ArrayList<String>() {
+    // `stream` is defined in ArrayList, so it was possible to declare it in 1.0 without an 'override' keyword
+    fun stream(): java.util.stream.Stream<String> = super.stream()
+
+    // `sort` is defined in ArrayList, so it was impossible to declare it in 1.0 without an 'override' keyword
+    fun sort(c: Comparator<in String>?) {
+        super.sort(c)
+    }
+}
+
+interface A2 : List<String> {
+    override fun stream(): java.util.stream.Stream<String> = null!!
+}
+
+class B : <!INAPPLICABLE_CANDIDATE!>Throwable<!>("", null, false, false)
+
+class B1 : RuntimeException() {
+    override fun fillInStackTrace(): Throwable { // 'override' keyword must be prohibited, as it was in 1.0.x
+        return this
+    }
+}
+
+class A3(val x: List<String>) : List<String> by x
+
+fun Throwable.fillInStackTrace() = 1
+
+fun foo(x: List<String>, y: Throwable, z: A3) {
+    x.stream()
+    java.util.<!UNRESOLVED_REFERENCE!>ArrayList<!><String>().<!UNRESOLVED_REFERENCE!>stream<!>()
+
+    y.fillInStackTrace() checkType { <!UNRESOLVED_REFERENCE!>_<!><Int>() }
+
+    HashMap<String, Int>().getOrDefault(Any(), null)
+
+    // Falls back to extension in stdlib
+    y.printStackTrace()
+
+    z.stream()
+}
+
+interface X {
+    fun foo(): Int = 1
+    val hidden: Boolean
+}
+
+class Y : X {
+    // There should not be UNSUPPORTED_FEATURE diagnostic
+    override fun foo() = 1
+    override var hidden: Boolean = true
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt
new file mode 100644
index 00000000000..0238b3d455e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithDisabledFeature.fir.kt
@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_DESTRUCTURED_PARAMETER_ENTRY, -UNUSED_ANONYMOUS_PARAMETER
+
+data class Foo1(val x: String, val y: String, val z: String = "")
+
+fun main() {
+    val (x1,y1,) = Pair(1,2)
+    val (x2, y2: Number,) = Pair(1,2)
+    val (x3,y3,z3,) = Foo1("", "", )
+    val (x4,y4: CharSequence,) = Foo1("", "", "",)
+    val (x41,y41: CharSequence,/**/) = Foo1("", "", "",)
+
+    val x5: (Pair<Int, Int>, Int) -> Unit = { (x,y,),z, -> }
+    val x6: (Foo1, Int) -> Any = { (x,y,z: CharSequence,), z1: Number, -> 1 }
+    val x61: (Foo1, Int) -> Any = { (x,y,z: CharSequence,/**/), z1: Number,/**/ -> 1 }
+
+    for ((i, j,) in listOf(Pair(1,2))) {}
+    for ((i: Any,) in listOf(Pair(1,2))) {}
+    for ((i: Any,/**/) in listOf(Pair(1,2))) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithEnabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithEnabledFeature.fir.kt
new file mode 100644
index 00000000000..4bf34c3afc0
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/multiVariableDeclarationWithEnabledFeature.fir.kt
@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_DESTRUCTURED_PARAMETER_ENTRY, -UNUSED_ANONYMOUS_PARAMETER
+// !LANGUAGE: +TrailingCommas
+
+data class Foo1(val x: String, val y: String, val z: String = "")
+
+fun main() {
+    val (x1,y1,) = Pair(1, 2)
+    val (x2, y2: Number,) = Pair(1,2)
+    val (x3,y3,z3,) = Foo1("", "",)
+    val (x4,y4: CharSequence,) = Foo1("", "", "",)
+    val (x41,y41: CharSequence,/**/) = Foo1("", "", "",)
+
+    val x5: (Pair<Int, Int>, Int) -> Unit = { (x,y,),z, -> }
+    val x6: (Foo1, Int) -> Any = { (x,y,z: CharSequence,), z2: Number, -> 1 }
+    val x61: (Foo1, Int) -> Any = { (x,y,z: CharSequence,/**/), z2: Number,/**/ -> 1 }
+
+    for ((i, j) in listOf(Pair(1,2))) {}
+    for ((i: Any,) in listOf(Pair(1,2))) {}
+    for ((i: Any,/**/) in listOf(Pair(1,2))) {}
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/noDisambiguation.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/noDisambiguation.fir.kt
new file mode 100644
index 00000000000..78df6b74bc2
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/noDisambiguation.fir.kt
@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_PARAMETER
+// !LANGUAGE: +TrailingCommas
+
+fun foo(vararg x: Int) = false
+fun foo() = true
+
+fun main() {
+    val x = foo()
+    val y = foo(<!SYNTAX!>,<!><!SYNTAX!><!>)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt
new file mode 100644
index 00000000000..7d12e9427a7
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithDisabledFeature.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_TYPEALIAS_PARAMETER, -CAST_NEVER_SUCCEEDS
+
+class Foo1<T1> {}
+
+interface Foo2<T1,>
+
+fun <T1, T2, T3>foo3() {}
+
+typealias Foo4<T1,T2,T3,T4> = Int
+
+class Foo5<T, K: T,>: Foo2<K,>
+
+fun <T> foo() {
+    val x1 = Foo1<Int,>()
+    val x2: Foo2<Int,>? = null
+    val x21: Foo2<Int,/**/>? = null
+    val x3 = foo3<
+            Int,
+            String,
+            Float,
+            >()
+    val x4: Foo4<Comparable<Int,>, Iterable<Comparable<Float,>,>, Double, T,
+            >? = null as Foo4<Comparable<Int,>, Iterable<Comparable<Float,>,>, Double, T,>
+    val x5: (Float,) -> Unit = {}
+    val x6: Pair<(Float, Comparable<T,>,) -> Unit, (Float,) -> Unit,>? = null
+    val x61: Pair<(Float, Comparable<T,/**/>,/**/) -> Unit, (Float,/**/) -> Unit,/**/>? = null
+}
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithEnabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithEnabledFeature.fir.kt
new file mode 100644
index 00000000000..3485444781e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeArgumentsWithEnabledFeature.fir.kt
@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_TYPEALIAS_PARAMETER, -CAST_NEVER_SUCCEEDS
+// !LANGUAGE: +TrailingCommas
+
+class Foo1<T1> {}
+
+interface Foo2<T1,>
+
+fun <T1, T2, T3>foo3() {}
+
+typealias Foo4<T1,T2,T3,T4> = Int
+
+class Foo5<T, K: T,>: Foo2<K,>
+
+fun <T>foo () {
+    val x1 = Foo1<Int,>()
+    val x2: Foo2<Int,>? = null
+    val x21: Foo2<Int,/**/>? = null
+    val x3 = foo3<
+            Int,
+            String,
+            Float,
+            >()
+    val x4: Foo4<Comparable<Int,>, Iterable<Comparable<Float,>,>, Double, T,
+            >? = null as Foo4<Comparable<Int,>, Iterable<Comparable<Float,>,>, Double, T,>
+    val x5: (Float,) -> Unit = {}
+    val x6: Pair<(Float, Comparable<T,>,) -> Unit, (Float,) -> Unit,>? = null
+    val x61: Pair<(Float, Comparable<T,/**/>,/**/) -> Unit, (Float,/**/) -> Unit,/**/>? = null
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt
new file mode 100644
index 00000000000..a6b085bd057
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithDisabledFeature.fir.kt
@@ -0,0 +1,48 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_TYPEALIAS_PARAMETER
+
+@Target(AnnotationTarget.TYPE)
+annotation class Anno
+
+class Foo1<T1,>
+
+class Foo2<
+        T1,
+        T2: T1,
+        > {
+    fun <T1,
+            T2, > foo2() {}
+
+    internal inner class B<T,T2,>
+}
+
+interface A<T,>
+
+interface A1<T,/**/>
+
+fun <T,> foo1() {}
+
+fun <T,/**/> foo11() {}
+
+fun <T1,
+        T2,
+        > T2?.foo2() {}
+
+val <T,> T.bar1 get() = null
+
+var <
+        T4,
+        > T4?.bar2
+    get() = null
+    set(value) {
+
+    }
+
+typealias Foo3<T1, @Anno T2,> = List<T2>
+
+typealias Foo4<T1, @Anno T2,/**/> = List<T2>
+
+fun main() {
+    fun <T,> foo10() {
+        fun <T1,T2,T3,> foo10() {}
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithEnabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithEnabledFeature.fir.kt
new file mode 100644
index 00000000000..bb48ef27620
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/typeParametersWithEnabledFeature.fir.kt
@@ -0,0 +1,51 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_TYPEALIAS_PARAMETER
+// !LANGUAGE: +TrailingCommas
+
+@Target(AnnotationTarget.TYPE)
+annotation class Anno
+
+class Foo1<T1,>
+
+class Foo2<
+        T1,
+        T2: T1,
+        > {
+    fun <T1,
+            T2, > foo2() {}
+
+    internal inner class B<T,T2,>
+}
+
+interface A<T,>
+
+interface A1<T,/**/>
+
+fun <T,> foo1() {}
+
+fun <T,/**/> foo11() {}
+
+inline fun <reified T1, T2, reified T3,> foo2() {}
+
+fun <T1,
+        T2,
+        > T2?.foo3() {}
+
+val <T,> T.bar1 get() = null
+
+var <
+        T4,
+        > T4?.bar2
+    get() = null
+    set(value) {
+
+    }
+
+typealias Foo3<T1, @Anno T2,> = List<T2>
+
+typealias Foo4<T1, @Anno T2,/**/> = List<T2>
+
+fun main() {
+    fun <T,> foo10() {
+        fun <T1,T2,T3,> foo10() {}
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt
new file mode 100644
index 00000000000..989def7b079
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithDisabledFeature.fir.kt
@@ -0,0 +1,73 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -UNUSED_ANONYMOUS_PARAMETER
+
+@Target(AnnotationTarget.TYPE)
+annotation class Anno1(val x: IntArray)
+
+@Target(AnnotationTarget.TYPEALIAS)
+annotation class Anno2(val x: DoubleArray)
+
+fun foo1(vararg x: Any) {}
+fun foo2(x: (Any, Any) -> Unit) {}
+fun foo3(x: Any, y: () -> Unit) {}
+
+open class A1(vararg x: Any) {
+    operator fun get(x: Any, y: Any) = 10
+}
+
+open class A2(x: Int, y: () -> Unit) {}
+
+class B(): A1({},) {
+
+}
+
+@Anno2(
+    [
+        0.4,
+        .1,
+    ]
+)
+typealias A3 = B
+
+fun main1() {
+    foo1(1, 2, 3,)
+    foo1({},)
+    foo3(10,) {}
+    foo3(10,/**/) {}
+
+    val x1 = A1(1, 2, 3,)
+    val y1 = A1({},)
+    val z1 = A2(10,) {}
+
+    foo2({ x, y -> kotlin.Unit },)
+    foo2({ x, y -> kotlin.Unit },/**/)
+
+    val foo = listOf(
+        println(1),
+        "foo bar something",
+        )
+
+    val x2 = x1[
+            1,
+            2,
+    ]
+
+    val x3 = x1[{},{},]
+    val x31 = x1[{},{},/**/]
+
+    val x4: @Anno1([
+                      1, 2,
+                  ]) Float = 0f
+
+    foo1(object {},)
+    foo1(object {},/**/)
+    foo1(fun () {},)
+    foo1(if (true) 1 else 2,)
+
+    foo1(return,)
+}
+
+fun main2(x: A1) {
+    val x1 = x[object {}, return, ]
+    val x2 = x[fun () {}, throw Exception(), ]
+    val x3 = x[fun () {}, throw Exception(),/**/ ]
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithEnabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithEnabledFeature.fir.kt
new file mode 100644
index 00000000000..7c3473a0f05
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueArgumentsWithEnabledFeature.fir.kt
@@ -0,0 +1,69 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_VARIABLE, -UNUSED_ANONYMOUS_PARAMETER
+// !LANGUAGE: +TrailingCommas
+
+@Target(AnnotationTarget.TYPE)
+annotation class Anno1(val x: IntArray)
+
+@Target(AnnotationTarget.TYPEALIAS)
+annotation class Anno2(val x: DoubleArray)
+
+fun foo1(vararg x: Any) {}
+fun foo2(x: (Any, Any) -> Unit) {}
+fun foo3(x: Any, y: () -> Unit) {}
+
+open class A1(vararg x: Any) {
+    operator fun get(x: Any, y: Any) = 10
+}
+
+open class A2(x: Any, y: () -> Unit)
+
+class B(): A1({},) {
+
+}
+
+@Anno2(
+    [
+        0.4,
+        .1,
+    ]
+)
+typealias A3 = B
+
+fun main1() {
+    foo1(1, 2, 3,/**/)
+    foo1({},)
+    foo3(10,/**/) {}
+
+    val x1 = A1(1, 2, 3,)
+    val y1 = A1({},)
+    val z1 = A2(10,) {}
+
+    foo2({ x, y -> kotlin.Unit },/**/)
+
+    val foo = listOf(
+        println(1),
+        "foo bar something",
+    )
+
+    val x2 = x1[
+        1,
+        2,
+    ]
+
+    val x3 = x1[{},{},/**/]
+
+    val x4: @Anno1([
+                  1, 2,/**/
+                  ]) Float = 0f
+
+    foo1(object {},)
+    foo1(fun () {},)
+    foo1(if (true) 1 else 2,/**/)
+
+    foo1(return,)
+}
+
+fun main2(x: A1) {
+    val x1 = x[object {}, return, ]
+    val x2 = x[fun () {}, throw Exception(), /**/]
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt
new file mode 100644
index 00000000000..24092568b53
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithDisabledFeature.fir.kt
@@ -0,0 +1,120 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_ANONYMOUS_PARAMETER -UNUSED_VARIABLE
+
+open class Foo1(x: Int = 10, y: Float = 0f,)
+
+class Foo2(
+    val x: Int = 10,
+    var y: Float,
+): Foo1(x, y,) {
+    constructor(
+        x: Float,
+        y: Int = 10,
+    ): this(1, 1f,) {}
+
+    var x1: Int
+        get() = 10
+        set(value,) {
+
+        }
+
+    var x2: Int
+        get() = 10
+        set(
+            x2,
+        ) {}
+
+    var x3: (Int) -> Unit
+        get() = {}
+        set(x2: (Int) -> Unit,) {}
+
+    var x4: (Int) -> Unit
+        get() = {}
+        set(x2: (Int) -> Unit,/**/) {}
+}
+
+enum class Foo3(x: Int, )
+
+fun foo4(x: Int, y: Comparable<Float>,) {}
+
+fun foo5(x: Int = 10,) {}
+
+fun foo6(vararg x: Int,) {}
+
+fun foo7(y: Float, vararg x: Int,) {}
+
+val foo8: (Int, Int,) -> Int = fun(
+    x,
+    y,
+    ): Int {
+    return x + y
+}
+
+val foo9: (Int, Int, Int,) -> Int =
+    fun (x, y: Int, z,): Int {
+        return x + y
+    }
+
+open class Foo10(x: Int = 10, y: Float = 0f)
+
+class Foo11: Foo10 {
+    constructor(
+        x: Float
+    ): <!INAPPLICABLE_CANDIDATE!>super<!>(1, 1f,)
+}
+
+class Foo12: Foo10 {
+    constructor(
+        x: Float
+    ): <!INAPPLICABLE_CANDIDATE!>super<!>(1, 1f,/**/)
+}
+
+fun main() {
+    val x1 = {
+            x: Comparable<Comparable<Number>>,
+            y: Iterable<Iterable<Number>>,
+        ->
+        println("1")
+    }
+    val x2 = { x: Comparable<Comparable<Number>>,
+        -> println("1")
+    }
+    val x3: ((Int,) -> Int) -> Unit = { x: (Int,) -> Int, -> println("1") }
+    val x4: ((Int,) -> Int) -> Unit = { x, -> println("1") }
+
+    fun foo10(x:Int,y:Int,) {
+        fun foo10(x:Int,y:Int,) {}
+    }
+    fun foo101(x:Int,y:Int,/**/) {
+        fun foo10(x:Int,y:Int,/**/) {}
+    }
+
+    try {
+        println(1)
+    } catch (e: Exception,) {
+
+    }
+
+    try {
+        println(1)
+    } catch (e: Exception,) {
+
+    } catch (e: Exception,) {
+
+    }
+
+    try {
+        println(1)
+    } catch (e: Exception,) {
+
+    } finally {
+
+    }
+
+    try {
+        println(1)
+    } catch (e: Exception,/**/) {
+
+    } finally {
+
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithEnabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithEnabledFeature.fir.kt
new file mode 100644
index 00000000000..649e2491779
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/valueParametersWithEnabledFeature.fir.kt
@@ -0,0 +1,104 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER, -UNUSED_ANONYMOUS_PARAMETER, -UNUSED_VARIABLE
+// !LANGUAGE: +TrailingCommas
+
+open class Foo1(x: Int = 10, y: Float = 0f,)
+
+class Foo2(
+    val x: Int = 10,
+    var y: Float,
+): Foo1(x, y) {
+    constructor(
+        x: Float,
+        y: Int = 10,
+        ): this(1, 1f,) {
+
+    }
+}
+
+enum class Foo3(x: Int, )
+
+fun foo4(x: Int, y: Comparable<Float>,) {}
+
+fun foo5(x: Int = 10,) {}
+
+fun foo6(vararg x: Int,) {}
+
+fun foo61(vararg x: Int,/**/) {}
+
+fun foo7(y: Float, vararg x: Int,) {}
+
+val foo8: (Int, Int,) -> Int = fun(
+    x,
+    y,
+    ): Int {
+    return x + y
+}
+
+val foo9: (Int, Int, Int,) -> Int =
+    fun (x, y: Int, z,): Int {
+        return x + y
+    }
+
+open class Foo10(x: Int = 10, y: Float = 0f)
+
+class Foo11: Foo10 {
+    constructor(
+        x: Float
+    ): <!INAPPLICABLE_CANDIDATE!>super<!>(1, 1f,)
+}
+
+class Foo12: Foo10 {
+    constructor(
+        x: Float
+    ): <!INAPPLICABLE_CANDIDATE!>super<!>(1, 1f,/**/)
+}
+
+fun main() {
+    val x1 = {
+            x: Comparable<Comparable<Number>>,
+            y: Iterable<Iterable<Number>>,
+        ->
+        println("1")
+    }
+    val x11 = {
+            x: Comparable<Comparable<Number>>,
+            y: Iterable<Iterable<Number>>,/**/
+        ->
+        println("1")
+    }
+    val x2 = { x: Comparable<Comparable<Number>>,
+        -> println("1")
+    }
+    val x3: ((Int,) -> Int) -> Unit = { x: (Int,) -> Int, -> println("1") }
+    val x4: ((Int,) -> Int) -> Unit = { x, -> println("1") }
+
+    try {
+        println(1)
+    } catch (e: Exception,) {
+
+    }
+
+    try {
+        println(1)
+    } catch (e: Exception,) {
+
+    } catch (e: Exception,) {
+
+    }
+
+    try {
+        println(1)
+    } catch (e: Exception,) {
+
+    } finally {
+
+    }
+
+    try {
+        println(1)
+    } catch (e: Exception,/**/) {
+
+    } finally {
+
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt
new file mode 100644
index 00000000000..46094fed33d
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.fir.kt
@@ -0,0 +1,49 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_EXPRESSION -NAME_SHADOWING
+
+fun foo1(x: Any) = when (x) {
+    Comparable::class,
+    Iterable::class,
+    String::class,
+        -> println(1)
+    else -> println(3)
+}
+
+fun foo2(x: Any) {
+    val z = when (val y: Int = x as Int) {
+        1, -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo3(x: (Any) -> Any) {
+    val z = when (val y: (Any) -> Any = x) {
+        {x: Any, -> x}, {y: Any, -> y}, -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo4(x: Any) {
+    val z = when (x) {
+        is Int, is Double, -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo5(x: Int, y: IntArray, z: IntArray) {
+    val u = when (x) {
+        in y,
+        in z,
+            -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo6(x: Boolean?) = when (x) {
+    true, false, -> println(1)
+    null, -> println(1)
+}
+
+fun foo7(x: Boolean?) = when (x) {
+    true, false,/**/ -> println(1)
+    null,/**/ -> println(1)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithEnabledFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithEnabledFeature.fir.kt
new file mode 100644
index 00000000000..aabceebf900
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithEnabledFeature.fir.kt
@@ -0,0 +1,50 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -NAME_SHADOWING
+// !LANGUAGE: +TrailingCommas
+
+fun foo1(x: Any) = when (x) {
+    Comparable::class,
+    Iterable::class,
+    String::class,
+        -> println(1)
+    else -> println(3)
+}
+
+fun foo2(x: Any) {
+    val z = when (val y: Int = x as Int) {
+        1, -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo3(x: (Any) -> Any) {
+    val z = when (val y: (Any) -> Any = x) {
+        {x: Any, -> x}, {y: Any, -> y}, -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo4(x: Any) {
+    val z = when (x) {
+        is Int, is Double, -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo5(x: Int, y: IntArray, z: IntArray) {
+    val u = when (x) {
+        in y,
+        in z,
+            -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo6(x: Boolean?) = when (x) {
+    true, false, -> println(1)
+    null, -> println(1)
+}
+
+fun foo7(x: Boolean?) = when (x) {
+    true, false,/**/ -> println(1)
+    null,/**/ -> println(1)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/assignTry.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/assignTry.fir.kt
new file mode 100644
index 00000000000..abf739ca63f
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/assignTry.fir.kt
@@ -0,0 +1,111 @@
+// !WITH_NEW_INFERENCE
+// SKIP_TXT
+
+class ExcA : Exception()
+
+class ExcB : Exception()
+
+fun test2() {
+    val s: String? = try {
+        ""
+    }
+    catch (e: ExcA) {
+        null
+    }
+    catch (e: ExcB) {
+        10
+    }
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun test3() {
+    val s: String? = try {
+        ""
+    }
+    catch (e: ExcA) {
+        null
+    }
+    catch (e: ExcB) {
+        return
+    }
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun test4() {
+    val s: String? = try {
+        ""
+    }
+    catch (e: ExcA) {
+        null
+    }
+    finally {
+        ""
+    }
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun test5() {
+    val s: String? = try {
+        ""
+    }
+    catch (e: ExcA) {
+        null
+    }
+    finally {
+        return
+    }
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun test6() {
+    val s: String? = try {
+        ""
+    }
+    catch (e: ExcA) {
+        return
+    }
+    catch (e: ExcB) {
+        return
+    }
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun test7() {
+    val s: String? = try {
+        ""
+    }
+    catch (e: ExcA) {
+        ""
+    }
+    catch (e: ExcB) {
+        ""
+    }
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun test8() {
+    val s = try {
+        ""
+    } catch (e: ExcA) {
+        null
+    }
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun test9() {
+    val s = try {
+        ""
+    } catch (e: ExcA) {
+        ""
+    }
+    s.length
+}
+
+fun test10() {
+    val x = try {
+        ""
+    } finally {
+        42
+    }
+    x.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/boundedSmartcasts.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/boundedSmartcasts.fir.kt
new file mode 100644
index 00000000000..ea8f2aab7a3
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/boundedSmartcasts.fir.kt
@@ -0,0 +1,101 @@
+// !WTIH_NEW_INFERENCE
+// SKIP_TXT
+
+class ExcA : Exception()
+class ExcB : Exception()
+
+fun test0(x: Int?) {
+    val y = try {
+        x
+    } finally {
+
+    }
+
+    if (x != null) {
+        x.inc()
+        y.<!AMBIGUITY!>inc<!>()
+    }
+
+    if (y != null) {
+        x.<!AMBIGUITY!>inc<!>()
+        y.inc()
+    }
+}
+
+fun test1(x: Int?) {
+    val y = try {
+        x
+    }
+    catch (e: Exception) {
+        42
+    }
+
+    if (x != null) {
+        x.inc()
+        y.<!AMBIGUITY!>inc<!>()
+    }
+
+    if (y != null) {
+        x.<!AMBIGUITY!>inc<!>()
+        y.inc()
+    }
+}
+
+fun test2(x: Int?) {
+    val y = try {
+        x
+    }
+    catch (e: Exception) {
+        x
+    }
+
+    if (x != null) {
+        x.inc()
+        y.<!AMBIGUITY!>inc<!>()
+    }
+
+    if (y != null) {
+        x.<!AMBIGUITY!>inc<!>()
+        y.inc()
+    }
+}
+
+fun test3(x: Int?) {
+    val y = try {
+        x
+    } catch (e: Exception) {
+        return
+    }
+
+    if (x != null) {
+        x.inc()
+        y.<!AMBIGUITY!>inc<!>()
+    }
+
+    if (y != null) {
+        x.<!AMBIGUITY!>inc<!>()
+        y.inc()
+    }
+}
+
+fun test5(x: Int?) {
+    val y = try {
+        x
+    }
+    catch (e: ExcA) {
+        return
+    }
+    catch (e: ExcB) {
+        x
+    }
+
+    if (x != null) {
+        x.inc()
+        y.<!AMBIGUITY!>inc<!>()
+    }
+
+    if (y != null) {
+        x.<!AMBIGUITY!>inc<!>()
+        y.inc()
+    }
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/catchRedeclaration.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/catchRedeclaration.fir.kt
new file mode 100644
index 00000000000..71268d77c13
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/catchRedeclaration.fir.kt
@@ -0,0 +1,54 @@
+// !WTIH_NEW_INFERENCE
+// SKIP_TXT
+
+class MyException : Exception() {
+    val myField = "field"
+
+    fun myFun() {}
+}
+
+fun test1() {
+    val e = "something"
+    try {}
+    catch (e: Exception) {
+        e.message
+        e.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun test2() {
+    try {}
+    catch (e: Exception) {
+        val e = "something"
+        e.<!UNRESOLVED_REFERENCE!>message<!>
+        e.length
+    }
+}
+
+fun test3() {
+    try {}
+    catch (e: MyException) {
+        e.myField
+    }
+}
+
+fun test4() {
+    try {}
+    catch (e: Exception) {
+        val a = 42
+        val a = "foo"
+    }
+}
+
+fun test5() {
+    try {}
+    catch (e: Exception) {
+        val a: Int = 42
+        try {}
+        catch (e: MyException) {
+            e.myFun()
+            val a: String = ""
+            a.length
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/correctSmartcasts.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/correctSmartcasts.fir.kt
new file mode 100644
index 00000000000..2170cb05df1
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/correctSmartcasts.fir.kt
@@ -0,0 +1,88 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER
+// SKIP_TXT
+// Related issue: KT-28370
+
+class ExcA : Exception()
+class ExcB : Exception()
+
+fun test1(s: String?) {
+    var t2: Boolean? = true
+    if (t2 != null) {
+        try {
+            t2 = null
+        }
+        catch (e: Exception) {
+            requireNotNull(s)
+        }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>()
+        s.length
+    }
+}
+
+fun test2(s: String?) {
+    var t2: Boolean? = true
+    if (t2 != null) {
+        try {
+            t2 = null
+        }
+        finally {
+            requireNotNull(s)
+            t2 = true
+        }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>()
+        s.length
+    }
+}
+
+fun test3() {
+    var s: String? = null
+    s = ""
+    try {
+
+    }
+    catch (e: Exception) {
+        s = null
+        return
+    }
+    s.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test4() {
+    var s: String? = null
+    s = ""
+    try {
+
+    }
+    catch (e: ExcA) {
+        s = null
+        return
+    }
+    catch (e: ExcB) {
+
+    }
+    s.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test5(s: String?) {
+    try {
+        requireNotNull(s)
+    }
+    catch (e: ExcA) {
+        return
+    }
+    catch (e: ExcB) {
+
+    }
+    s.length
+}
+
+fun test6(s: String?) {
+    try {
+        requireNotNull(s)
+    }
+    catch (e: Exception) {
+        return
+    }
+    s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/correctSmartcasts_after.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/correctSmartcasts_after.fir.kt
new file mode 100644
index 00000000000..67e4ab0e4cc
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/correctSmartcasts_after.fir.kt
@@ -0,0 +1,89 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +NewDataFlowForTryExpressions
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER
+// SKIP_TXT
+// Related issue: KT-28370
+
+class ExcA : Exception()
+class ExcB : Exception()
+
+fun test1(s: String?) {
+    var t2: Boolean? = true
+    if (t2 != null) {
+        try {
+            t2 = null
+        }
+        catch (e: Exception) {
+            requireNotNull(s)
+        }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>()
+        s.length
+    }
+}
+
+fun test2(s: String?) {
+    var t2: Boolean? = true
+    if (t2 != null) {
+        try {
+            t2 = null
+        }
+        finally {
+            requireNotNull(s)
+            t2 = true
+        }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>()
+        s.length
+    }
+}
+
+fun test3() {
+    var s: String? = null
+    s = ""
+    try {
+
+    }
+    catch (e: Exception) {
+        s = null
+        return
+    }
+    s.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test4() {
+    var s: String? = null
+    s = ""
+    try {
+
+    }
+    catch (e: ExcA) {
+        s = null
+        return
+    }
+    catch (e: ExcB) {
+
+    }
+    s.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test5(s: String?) {
+    try {
+        requireNotNull(s)
+    }
+    catch (e: ExcA) {
+        return
+    }
+    catch (e: ExcB) {
+
+    }
+    s.length
+}
+
+fun test6(s: String?) {
+    try {
+        requireNotNull(s)
+    }
+    catch (e: Exception) {
+        return
+    }
+    s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falseNegativeSmartcasts.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falseNegativeSmartcasts.fir.kt
new file mode 100644
index 00000000000..80e1ae92909
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falseNegativeSmartcasts.fir.kt
@@ -0,0 +1,19 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER
+// Related issue: KT-28370
+
+fun test1(s1: String?) {
+    var s: String? = null
+    s = ""
+    try {
+        s = ""
+        requireNotNull(s1)
+    }
+    catch (e: Exception) {
+        return
+    }
+    finally {
+        s.length
+    }
+    s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falseNegativeSmartcasts_after.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falseNegativeSmartcasts_after.fir.kt
new file mode 100644
index 00000000000..511efb38d57
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falseNegativeSmartcasts_after.fir.kt
@@ -0,0 +1,20 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +NewDataFlowForTryExpressions
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER
+// Related issue: KT-28370
+
+fun test1(s1: String?) {
+    var s: String? = null
+    s = ""
+    try {
+        s = ""
+        requireNotNull(s1)
+    }
+    catch (e: Exception) {
+        return
+    }
+    finally {
+        s.length
+    }
+    s.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts.fir.kt
new file mode 100644
index 00000000000..cb73d68b460
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts.fir.kt
@@ -0,0 +1,106 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER
+// SKIP_TXT
+// Related issue: KT-28370
+
+class ExcA : Exception()
+class ExcB : Exception()
+
+fun test1() {
+    var x: String? = null
+    x = ""
+
+    try {
+        x = null
+    } catch (e: Exception) {
+        x.<!UNRESOLVED_REFERENCE!>length<!> // smartcast shouldn't be allowed (OOME could happen after `x = null`)
+        throw e
+    }
+    finally {
+        // smartcast shouldn't be allowed, `x = null` could've happened
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    // smartcast shouldn't be allowed, `x = null` could've happened
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+// With old DFA of try/catch info about unsound smartcasts after try
+//  removes only if there is at least one catch branch that not returns Nothing
+fun test2() {
+    var x: String? = null
+    x = ""
+
+    try {
+        x = null
+    } catch (e: Exception) {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    finally {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test3() {
+    var t2: Boolean? = true
+    if (t2 != null) { // or `t2 is Boolean`
+        try {
+            throw Exception()
+        } catch (e: Exception) {
+            t2 = null
+        }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>() // wrong smartcast, NPE
+    }
+}
+
+fun test4() {
+    var t2: Boolean? = true
+    if (t2 != null) { // or `t2 is Boolean`
+        try {
+            t2 = null
+        } finally { }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>() // wrong smartcast, NPE
+    }
+}
+
+fun test5() {
+    var s1: String? = null
+    var s2: String? = null
+    s1 = ""
+    s2 = ""
+    try {
+        TODO()
+    }
+    catch (e: ExcA) {
+        s1 = ""
+    }
+    catch (e: ExcB) {
+        s2 = null
+        return
+    }
+    finally {
+        s1.length
+        s2.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    s1.length
+    s2.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test6(s1: String?, s2: String?) {
+    var s: String? = null
+    s = ""
+    try {
+        s = null
+        requireNotNull(s1)
+    }
+    catch (e: Exception) {
+        return
+    }
+    finally {
+        s.<!UNRESOLVED_REFERENCE!>length<!>
+        requireNotNull(s2)
+    }
+    s.<!UNRESOLVED_REFERENCE!>length<!>
+    s1.length
+    s2.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts_after.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts_after.fir.kt
new file mode 100644
index 00000000000..44309a29e07
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/falsePositiveSmartcasts_after.fir.kt
@@ -0,0 +1,108 @@
+// !WITH_NEW_INFERENCE
+// !LANGUAGE: +NewDataFlowForTryExpressions
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER
+// SKIP_TXT
+// Related issue: KT-28370
+
+class ExcA : Exception()
+class ExcB : Exception()
+
+fun test1() {
+    var x: String? = null
+    x = ""
+
+    try {
+        x = null
+    } catch (e: Exception) {
+        x.<!UNRESOLVED_REFERENCE!>length<!> // smartcast shouldn't be allowed (OOME could happen after `x = null`)
+        throw e
+    }
+    finally {
+        // smartcast shouldn't be allowed, `x = null` could've happened
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    // smartcast shouldn't be allowed, `x = null` could've happened
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+// With old DFA of try/catch info about unsound smartcasts after try
+//  removes only if there is at least one catch branch that not returns Nothing
+fun test2() {
+    var x: String? = null
+    x = ""
+
+    try {
+        x = null
+    } catch (e: Exception) {
+        // BAD
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    finally {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test3() {
+    var t2: Boolean? = true
+    if (t2 != null) { // or `t2 is Boolean`
+        try {
+            throw Exception()
+        } catch (e: Exception) {
+            t2 = null
+        }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>() // wrong smartcast, NPE
+    }
+}
+
+fun test4() {
+    var t2: Boolean? = true
+    if (t2 != null) { // or `t2 is Boolean`
+        try {
+            t2 = null
+        } finally { }
+        t2.<!UNRESOLVED_REFERENCE!>not<!>() // wrong smartcast, NPE
+    }
+}
+
+fun test5() {
+    var s1: String? = null
+    var s2: String? = null
+    s1 = ""
+    s2 = ""
+    try {
+        TODO()
+    }
+    catch (e: ExcA) {
+        s1 = ""
+    }
+    catch (e: ExcB) {
+        s2 = null
+        return
+    }
+    finally {
+        s1.length
+        s2.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+    s1.length
+    s2.<!UNRESOLVED_REFERENCE!>length<!>
+}
+
+fun test6(s1: String?, s2: String?) {
+    var s: String? = null
+    s = ""
+    try {
+        s = null
+        requireNotNull(s1)
+    }
+    catch (e: Exception) {
+        return
+    }
+    finally {
+        s.<!UNRESOLVED_REFERENCE!>length<!>
+        requireNotNull(s2)
+    }
+    s.<!UNRESOLVED_REFERENCE!>length<!>
+    s1.length
+    s2.length
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/tryCatch/tryExpression.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/tryExpression.fir.kt
new file mode 100644
index 00000000000..dfb2e98a923
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/tryCatch/tryExpression.fir.kt
@@ -0,0 +1,35 @@
+// !WITH_NEW_INFERENCE
+// SKIP_TXT
+
+class ExcA : Exception()
+
+class ExcB(val map: Map<Int, Int>) : Exception()
+
+fun test0(): List<Int> = run {
+    try {
+        emptyList()
+    } finally {
+        ""
+        fun foo() {}
+    }
+}
+
+fun test1(): Map<Int, Int> = run {
+    try {
+        emptyMap()
+    } catch (e: ExcA) {
+        emptyMap()
+    } catch (e: ExcB) {
+        e.map
+    } finally {
+        ""
+    }
+}
+
+fun test2(): Map<Int, Int> = run {
+    try {
+        emptyMap()
+    } catch (e: ExcA) {
+        mapOf("" to "")
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliases.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliases.fir.kt
new file mode 100644
index 00000000000..f986b5d6eb6
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliases.fir.kt
@@ -0,0 +1,3 @@
+// FILE: test.kt
+val fooException = Exception("foo")
+val barException = kotlin.<!UNRESOLVED_REFERENCE!>Exception<!>("bar")
diff --git a/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithApiVersion1_0.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithApiVersion1_0.fir.kt
new file mode 100644
index 00000000000..80cc7440061
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithApiVersion1_0.fir.kt
@@ -0,0 +1,5 @@
+// !LANGUAGE: +TypeAliases
+// !API_VERSION: 1.0
+// FILE: test.kt
+val fooException = Exception("foo")
+val barException = kotlin.<!UNRESOLVED_REFERENCE!>Exception<!>("bar")
diff --git a/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithoutFeature.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithoutFeature.fir.kt
new file mode 100644
index 00000000000..66b41670c8e
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/typealias/exceptionTypeAliasesInvisibleWithoutFeature.fir.kt
@@ -0,0 +1,4 @@
+// !LANGUAGE: -TypeAliases
+// FILE: test.kt
+val fooException = Exception("foo")
+val barException = kotlin.<!UNRESOLVED_REFERENCE!>Exception<!>("bar")
diff --git a/compiler/testData/diagnostics/testsWithStdLib/typealias/hashMapTypeAlias.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/typealias/hashMapTypeAlias.fir.kt
new file mode 100644
index 00000000000..1cb5f2b94a5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/typealias/hashMapTypeAlias.fir.kt
@@ -0,0 +1,20 @@
+import kotlin.test.*
+import java.util.*
+
+typealias HM<Kt, Vt> = HashMap<Kt, Vt>
+
+fun <K, V, M : MutableMap<in K, MutableList<V>>> updateMap(map: M, k: K, v: V): M {
+    map[k]!!.add(v)
+    return map
+}
+
+val nameToTeam = listOf("Alice" to "Marketing", "Bob" to "Sales", "Carol" to "Marketing")
+val namesByTeam = nameToTeam.groupBy({ it.second }, { it.first })
+
+val mutableNamesByTeam1 = updateMap(HM(), "", "")
+val mutableNamesByTeam2 = updateMap(HashMap(), "", "")
+
+fun test() {
+    assertEquals(namesByTeam, mutableNamesByTeam1)
+    assertEquals(namesByTeam, mutableNamesByTeam2)
+}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors.fir.kt
new file mode 100644
index 00000000000..64b9eb0da5b
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors.fir.kt
@@ -0,0 +1,8 @@
+// FILE: test.kt
+typealias RunnableT = java.lang.Runnable
+typealias ComparatorT<T> = java.util.Comparator<T>
+typealias ComparatorStrT = ComparatorT<String>
+
+val test1 = RunnableT { }
+val test2 = ComparatorT<String> { s1, s2 -> s1.compareTo(s2) }
+val test3 = ComparatorStrT { s1, s2 -> s1.<!UNRESOLVED_REFERENCE!>compareTo<!>(s2) }
diff --git a/compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors2.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors2.fir.kt
new file mode 100644
index 00000000000..a745898d565
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/typealias/typeAliasSamAdapterConstructors2.fir.kt
@@ -0,0 +1,27 @@
+// FILE: JHost.java
+public class JHost {
+    public static interface Runnable {
+        void run();
+    }
+
+    public static interface Consumer<T> {
+        void consume(T x);
+    }
+
+    public static interface Consumer2<T1, T2> {
+        void run(T1 x1, T2 x2);
+    }
+}
+
+// FILE: test.kt
+typealias R = JHost.Runnable
+typealias C<T> = JHost.Consumer<T>
+typealias CStr = JHost.Consumer<String>
+typealias CStrList = JHost.Consumer<List<String>>
+typealias C2<T> = JHost.Consumer2<T, T>
+
+val test1 = <!UNRESOLVED_REFERENCE!>R<!> { }
+val test2 = <!UNRESOLVED_REFERENCE!>C<!><String> { s -> <!AMBIGUITY!>println<!>(s.<!UNRESOLVED_REFERENCE!>length<!>) }
+val test3 = <!UNRESOLVED_REFERENCE!>CStr<!> { s -> <!AMBIGUITY!>println<!>(s.<!UNRESOLVED_REFERENCE!>length<!>) }
+val test4 = <!UNRESOLVED_REFERENCE!>CStrList<!> { ss -> <!AMBIGUITY, UNRESOLVED_REFERENCE, UNRESOLVED_REFERENCE!>for (s in ss) { <!AMBIGUITY!>println<!>(s.<!UNRESOLVED_REFERENCE!>length<!>) }<!> }
+val test5 = <!UNRESOLVED_REFERENCE!>C2<!><Int> { a, b -> val x: Int = a <!AMBIGUITY!>+<!> b; println(x)}
diff --git a/compiler/testData/diagnostics/testsWithStdLib/varargs/kt3213.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/varargs/kt3213.fir.kt
new file mode 100644
index 00000000000..33f8c6d3900
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/varargs/kt3213.fir.kt
@@ -0,0 +1,7 @@
+// !CHECK_TYPE
+
+fun test(a: Array<out String>) {
+    val b = a.toList()
+
+    b checkType { <!UNRESOLVED_REFERENCE!>_<!><List<String>>() }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/varargs/kt4172j.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/varargs/kt4172j.fir.kt
new file mode 100644
index 00000000000..4ab40699fd5
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/varargs/kt4172j.fir.kt
@@ -0,0 +1,9 @@
+// FILE: A.java
+public class A {
+    public static void main(String[] args) {}
+}
+
+// FILE: 1.kt
+fun main() {
+    A.main(arrayOf())
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/varargs/kt5534.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/varargs/kt5534.fir.kt
new file mode 100644
index 00000000000..f98f23dd0ac
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/varargs/kt5534.fir.kt
@@ -0,0 +1,6 @@
+fun test() {
+    val p: Array<String> = arrayOf("a")
+    <!INAPPLICABLE_CANDIDATE!>foo<!>(*p)
+}
+
+fun foo(vararg a: String?) = a
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/when/kt10192.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/when/kt10192.fir.kt
new file mode 100644
index 00000000000..bb4ed7a89dd
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/when/kt10192.fir.kt
@@ -0,0 +1,20 @@
+fun test1() {
+    if (true) {
+        when (true) {
+            true -> println()
+        }
+    } else {
+        System.out?.println() // kotlin.Unit?
+    }
+}
+
+fun test2() {
+    val mlist = arrayListOf("")
+    if (true) {
+        when (true) {
+            true -> println()
+        }
+    } else {
+        mlist.add("") // kotlin.Boolean
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/when/kt10807.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/when/kt10807.fir.kt
new file mode 100644
index 00000000000..20ea3211028
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/when/kt10807.fir.kt
@@ -0,0 +1,17 @@
+import java.util.*
+import kotlin.comparisons.compareBy
+import kotlin.comparisons.nullsLast
+
+class Foo(val a: String, val b: Int)
+
+fun getComp(): Comparator<Foo?> =
+        when {
+            else -> nullsLast(compareBy({ it.<!UNRESOLVED_REFERENCE!>a<!> }, { it.<!UNRESOLVED_REFERENCE!>b<!> }))
+        }
+
+fun getCompInverted(): Comparator<Foo?> =
+        nullsLast(
+                when {
+                    else -> compareBy({ it.<!UNRESOLVED_REFERENCE!>a<!> }, { it.<!UNRESOLVED_REFERENCE!>b<!> })
+                }
+        )
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/testsWithStdLib/when/noTypeArgumentsInConstructor.fir.kt b/compiler/testData/diagnostics/testsWithStdLib/when/noTypeArgumentsInConstructor.fir.kt
new file mode 100644
index 00000000000..b7212bcb280
--- /dev/null
+++ b/compiler/testData/diagnostics/testsWithStdLib/when/noTypeArgumentsInConstructor.fir.kt
@@ -0,0 +1,43 @@
+// !WITH_NEW_INFERENCE
+
+import java.util.*
+
+fun <T> nullable(x: T): T? = x
+
+@Suppress("UNUSED_PARAMETER")
+fun <T> select(x1: T, x2: T): T = x1
+
+val test1 =
+        listOf(1, 2, 3).mapNotNullTo(ArrayList()) {
+            if (true) nullable(it) else null
+        }
+
+val test2: MutableList<Int?> =
+        listOf(1, 2, 3).mapNotNullTo(ArrayList()) {
+            if (true) nullable(it) else null
+        }
+
+val test3: MutableList<Int> =
+        listOf(1, 2, 3).mapNotNullTo(ArrayList()) {
+            if (true) nullable(it) else null
+        }
+
+val test4: Collection<Int> =
+        listOf(1, 2, 3).flatMapTo(LinkedHashSet()) {
+            listOf(it)
+        }
+
+val test5: Collection<Int> =
+        listOf(1, 2, 3).flatMapTo(LinkedHashSet()) { // TODO
+            if (true) listOf(it) else listOf(it)
+        }
+
+val test6: Collection<Int> =
+        listOf(1, 2, 3).flatMapTo(LinkedHashSet<Int>()) {
+            if (true) listOf(it) else listOf(it)
+        }
+
+val test7: Collection<Int> =
+        listOf(1, 2, 3).flatMapTo(LinkedHashSet()) {
+            select(listOf(it), listOf(it))
+        }
\ No newline at end of file
-- 
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