[FIR] Support boolean elvis bound smartcasts

#KT-44511 Fixed

compiler/fir/analysis-tests/legacy-fir-tests/tests-gen/org/jetbrains/kotlin/fir/LazyBodyIsNotTouchedTilContractsPhaseTestGenerated.java

@@ -2818,6 +2818,11 @@ public class LazyBodyIsNotTouchedTilContractsPhaseTestGenerated extends Abstract
                 KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
             }
 
+            @TestMetadata("booleanElvisBoundSmartcast.kt")
+            public void testBooleanElvisBoundSmartcast() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans/booleanElvisBoundSmartcast.kt");
+            }
+
             @TestMetadata("booleanOperators.kt")
             public void testBooleanOperators() throws Exception {
                 runTest("compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans/booleanOperators.kt");

compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans/booleanElvisBoundSmartcast.fir.txt

+FILE: booleanElvisBoundSmartcast.kt
+    public final class A : R|kotlin/Any| {
+        public constructor(b: R|kotlin/Boolean|): R|A| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final val b: R|kotlin/Boolean| = R|<local>/b|
+            public get(): R|kotlin/Boolean|
+
+        public final fun foo(): R|kotlin/Unit| {
+        }
+
+    }
+    public final fun test_1(a: R|A?|): R|kotlin/Unit| {
+        when () {
+            R|<local>/a|?.{ $subj$.R|/A.b| } ?: Boolean(false) ->  {
+                R|<local>/a|.R|/A.foo|()
+            }
+            else ->  {
+                R|<local>/a|.<Inapplicable(INAPPLICABLE_WRONG_RECEIVER): /A.foo>#()
+            }
+        }
+
+    }
+    public final fun test_2(a: R|A?|): R|kotlin/Unit| {
+        when () {
+            R|<local>/a|?.{ $subj$.R|/A.b| } ?: Boolean(true) ->  {
+                R|<local>/a|.<Inapplicable(INAPPLICABLE_WRONG_RECEIVER): /A.foo>#()
+            }
+            else ->  {
+                R|<local>/a|.R|/A.foo|()
+            }
+        }
+
+    }

compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans/booleanElvisBoundSmartcast.kt

+// !LANGUAGE: +BooleanElvisBoundSmartCasts
+// ISSUE: KT-44511, also relates to KT-8492 and KT-26357
+
+class A(val b: Boolean) {
+    fun foo() {}
+}
+
+fun test_1(a: A?) {
+    if (a?.b ?: false) {
+        a.foo() // OK
+    } else {
+        a<!UNSAFE_CALL!>.<!>foo() // Error
+    }
+}
+
+fun test_2(a: A?) {
+    if (a?.b ?: true) {
+        a<!UNSAFE_CALL!>.<!>foo() // Error
+    } else {
+        a.foo() // OK
+    }
+}

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticTestGenerated.java

@@ -3194,6 +3194,12 @@ public class FirDiagnosticTestGenerated extends AbstractFirDiagnosticTest {
                     KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
                 }
 
+                @Test
+                @TestMetadata("booleanElvisBoundSmartcast.kt")
+                public void testBooleanElvisBoundSmartcast() throws Exception {
+                    runTest("compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans/booleanElvisBoundSmartcast.kt");
+                }
+
                 @Test
                 @TestMetadata("booleanOperators.kt")
                 public void testBooleanOperators() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticsWithLightTreeTestGenerated.java

@@ -3229,6 +3229,12 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
                     KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
                 }
 
+                @Test
+                @TestMetadata("booleanElvisBoundSmartcast.kt")
+                public void testBooleanElvisBoundSmartcast() throws Exception {
+                    runTest("compiler/fir/analysis-tests/testData/resolve/smartcasts/booleans/booleanElvisBoundSmartcast.kt");
+                }
+
                 @Test
                 @TestMetadata("booleanOperators.kt")
                 public void testBooleanOperators() throws Exception {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.resolve.dfa
 
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.PrivateForInline
 import org.jetbrains.kotlin.fir.contracts.FirResolvedContractDescription
@@ -14,6 +15,7 @@ import org.jetbrains.kotlin.fir.contracts.description.ConeConstantReference
 import org.jetbrains.kotlin.fir.contracts.description.ConeReturnsEffectDeclaration
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.expressions.*
+import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.references.FirControlFlowGraphReference
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
 import org.jetbrains.kotlin.fir.resolve.PersistentImplicitReceiverStack
@@ -26,6 +28,7 @@ import org.jetbrains.kotlin.fir.resolve.transformers.body.resolve.FirAbstractBod
 import org.jetbrains.kotlin.fir.resolve.transformers.body.resolve.resultType
 import org.jetbrains.kotlin.fir.symbols.AbstractFirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.CallableId
+import org.jetbrains.kotlin.fir.symbols.StandardClassIds
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.transformSingle
 import org.jetbrains.kotlin.name.FqName
@@ -1123,8 +1126,23 @@ abstract class FirDataFlowAnalyzer<FLOW : Flow>(
         }
     }
 
-    fun exitElvis() {
-        graphBuilder.exitElvis().mergeIncomingFlow()
+    fun exitElvis(elvisExpression: FirElvisExpression) {
+        val node = graphBuilder.exitElvis().mergeIncomingFlow()
+        if (!components.session.languageVersionSettings.supportsFeature(LanguageFeature.BooleanElvisBoundSmartCasts)) return
+        val lhs = elvisExpression.lhs
+        val rhs = elvisExpression.rhs
+        if (rhs is FirConstExpression<*> && rhs.kind == ConstantValueKind.Boolean) {
+            if (lhs.typeRef.coneType.classId != StandardClassIds.Boolean) return
+
+            val flow = node.flow
+            // a ?: false == true -> a != null
+            // a ?: true == false -> a != null
+            val elvisVariable = variableStorage.getOrCreateVariable(flow, elvisExpression)
+            val lhsVariable = variableStorage.getOrCreateVariable(flow, lhs)
+
+            val value = rhs.value as Boolean
+            flow.addImplication(elvisVariable.eq(!value) implies (lhsVariable.notEq(null)))
+        }
     }
 
     // Callable reference

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirControlFlowStatementsResolveTransformer.kt

@@ -244,7 +244,7 @@ class FirControlFlowStatementsResolveTransformer(transformer: FirBodyResolveTran
             }
         }
 
-        dataFlowAnalyzer.exitElvis()
+        dataFlowAnalyzer.exitElvis(elvisExpression)
         return result.compose()
     }
 }

compiler/testData/diagnostics/tests/smartCasts/elvis/basicOn.fir.kt

@@ -11,13 +11,13 @@ interface Order {
 fun foo(o: Any) {
     val order = o as? Order
     if (order?.expired ?: false) {
-        order<!UNSAFE_CALL!>.<!>doSomething()
+        order.doSomething()
     }
     else {
 
     }
     if (order?.notExpired() ?: false) {
-        order<!UNSAFE_CALL!>.<!>doSomething()
+        order.doSomething()
     }
 }
 
@@ -47,4 +47,4 @@ fun baz(o: Boolean?) {
     else {
         o<!UNSAFE_CALL!>.<!>hashCode()
     }
-}
+}
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