KT-1863 Wrong nullability for class derived from java classes.

 #KT-1863 In progress

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaDescriptorResolver.java

@@ -959,7 +959,7 @@ public class JavaDescriptorResolver {
                 continue;
             }
             
-            JetType transform = semanticServices.getTypeTransformer().transformToType(type, typeVariableResolver);
+            JetType transform = semanticServices.getTypeTransformer().transformToType(type, JavaTypeTransformer.TypeUsage.SUPERTYPE, typeVariableResolver);
 
             result.add(TypeUtils.makeNotNullable(transform));
         }

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/JavaTypeTransformer.java

@@ -33,11 +33,9 @@ import org.jetbrains.jet.lang.types.lang.PrimitiveType;
 import org.jetbrains.jet.rt.signature.JetSignatureReader;
 
 import javax.inject.Inject;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
+
+import static org.jetbrains.jet.lang.resolve.java.JavaTypeTransformer.TypeUsage.*;
 
 /**
  * @author abreslav
@@ -66,9 +64,11 @@ public class JavaTypeTransformer {
 
 
     @NotNull
-    public TypeProjection transformToTypeProjection(@NotNull final PsiType javaType,
+    private TypeProjection transformToTypeProjection(@NotNull final PsiType javaType,
             @NotNull final TypeParameterDescriptor typeParameterDescriptor,
-            @NotNull final TypeVariableResolver typeVariableByPsiResolver) {
+            @NotNull final TypeVariableResolver typeVariableByPsiResolver,
+            @NotNull final TypeUsage howThisTypeIsUsed
+    ) {
         TypeProjection result = javaType.accept(new PsiTypeVisitor<TypeProjection>() {
 
             @Override
@@ -85,12 +85,12 @@ public class JavaTypeTransformer {
 
                 PsiType bound = wildcardType.getBound();
                 assert bound != null;
-                return new TypeProjection(variance, transformToType(bound, TypeUsage.UPPER_BOUND, typeVariableByPsiResolver));
+                return new TypeProjection(variance, transformToType(bound, UPPER_BOUND, typeVariableByPsiResolver));
             }
 
             @Override
             public TypeProjection visitType(PsiType type) {
-                return new TypeProjection(transformToType(type, TypeUsage.TYPE_ARGUMENT, typeVariableByPsiResolver));
+                return new TypeProjection(transformToType(type, howThisTypeIsUsed, typeVariableByPsiResolver));
             }
         });
         return result;
@@ -136,7 +136,7 @@ public class JavaTypeTransformer {
                         if (psiMethod.isConstructor()) {
                             Set<JetType> supertypesJet = Sets.newHashSet();
                             for (PsiClassType supertype : typeParameter.getExtendsListTypes()) {
-                                supertypesJet.add(transformToType(supertype, TypeUsage.UPPER_BOUND, typeVariableResolver));
+                                supertypesJet.add(transformToType(supertype, UPPER_BOUND, typeVariableResolver));
                             }
                             return TypeUtils.intersect(JetTypeChecker.INSTANCE, supertypesJet);
                         }
@@ -144,20 +144,24 @@ public class JavaTypeTransformer {
 
                     TypeParameterDescriptor typeParameterDescriptor = typeVariableResolver.getTypeVariable(typeParameter.getName());
 
-                    if (howThisTypeIsUsed == TypeUsage.TYPE_ARGUMENT || howThisTypeIsUsed == TypeUsage.UPPER_BOUND) {
-                        // In Java: ArrayList<T>
-                        // In Kotlin: ArrayList<T>, not ArrayList<T?>
-                        // nullability will be taken care of in individual member signatures
-                        return typeParameterDescriptor.getDefaultType();
+                    // In Java: ArrayList<T>
+                    // In Kotlin: ArrayList<T>, not ArrayList<T?>
+                    // nullability will be taken care of in individual member signatures
+                    boolean nullable = !EnumSet.of(TYPE_ARGUMENT, UPPER_BOUND, SUPERTYPE_ARGUMENT).contains(howThisTypeIsUsed);
+                    if (nullable) {
+                        return TypeUtils.makeNullable(typeParameterDescriptor.getDefaultType());
                     }
                     else {
-                        return TypeUtils.makeNullable(typeParameterDescriptor.getDefaultType());
+                        return typeParameterDescriptor.getDefaultType();
                     }
                 }
                 else {
+                    // 'L extends List<T>' in Java is a List<T> in Kotlin, not a List<T?>
+                    boolean nullable = !EnumSet.of(SUPERTYPE_ARGUMENT, SUPERTYPE).contains(howThisTypeIsUsed);
+
                     JetType jetAnalog = getKotlinAnalog(new FqName(psiClass.getQualifiedName()));
                     if (jetAnalog != null) {
-                        return jetAnalog;
+                        return TypeUtils.makeNullableAsSpecified(jetAnalog, nullable);
                     }
 
                     final ClassDescriptor classData =
@@ -187,13 +191,15 @@ public class JavaTypeTransformer {
                             PsiType psiArgument = psiArguments[i];
                             TypeParameterDescriptor typeParameterDescriptor = parameters.get(i);
 
-                            arguments.add(transformToTypeProjection(psiArgument, typeParameterDescriptor, typeVariableResolver));
+                            TypeUsage howTheProjectionIsUsed = howThisTypeIsUsed == SUPERTYPE ? SUPERTYPE_ARGUMENT : TYPE_ARGUMENT;
+                            arguments.add(transformToTypeProjection(psiArgument, typeParameterDescriptor, typeVariableResolver, howTheProjectionIsUsed));
                         }
                     }
+
                     return new JetTypeImpl(
                             Collections.<AnnotationDescriptor>emptyList(),
                             classData.getTypeConstructor(),
-                            true,
+                            nullable,
                             arguments,
                             classData.getMemberScope(arguments));
                 }
@@ -291,6 +297,7 @@ public class JavaTypeTransformer {
         MEMBER_SIGNATURE_COVARIANT,
         MEMBER_SIGNATURE_CONTRAVARIANT,
         MEMBER_SIGNATURE_INVARIANT,
-        SUPERTYPE
+        SUPERTYPE,
+        SUPERTYPE_ARGUMENT
     }
 }

compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.jet

+// 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() {
+    Y().fooN() : Any
+    Y().barN(<!ERROR_COMPILE_TIME_VALUE!>null<!>);
+}
+

compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.jet

+// 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() {
+    Y().fooN() : Any
+    Y().barN(<!ERROR_COMPILE_TIME_VALUE!>null<!>);
+}
+

compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-SpecialTypes.jet

+// 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()<!UNSAFE_CALL!>.<!>length
+    Y().bar(null)
+}
+

compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-UserTypes.jet

+// 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()<!UNSAFE_CALL!>.<!>hashCode()
+    Y().bar(null)
+}
+