[FIR] Unwrap dispatcher type when determining property stability

If the modality of a property is not final, the modality of the dispatch
receiver can be used to determine if the property is stable. When
looking up the dispatch receiver symbol, make sure to unwrap the lower
bounds of flexible types.

^KT-61735 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -26058,6 +26058,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
                 runTest("compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleTypeReceiver.kt")
+            public void testFlexibleTypeReceiver() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/properties/flexibleTypeReceiver.kt");
+            }
+
             @Test
             @TestMetadata("inferPropertyTypeFromGetter.kt")
             public void testInferPropertyTypeFromGetter() throws Exception {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -26058,6 +26058,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
                 runTest("compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleTypeReceiver.kt")
+            public void testFlexibleTypeReceiver() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/properties/flexibleTypeReceiver.kt");
+            }
+
             @Test
             @TestMetadata("inferPropertyTypeFromGetter.kt")
             public void testInferPropertyTypeFromGetter() throws Exception {

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

@@ -26058,6 +26058,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
                 runTest("compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleTypeReceiver.kt")
+            public void testFlexibleTypeReceiver() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/properties/flexibleTypeReceiver.kt");
+            }
+
             @Test
             @TestMetadata("inferPropertyTypeFromGetter.kt")
             public void testInferPropertyTypeFromGetter() throws Exception {

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

@@ -26064,6 +26064,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
                 runTest("compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleTypeReceiver.kt")
+            public void testFlexibleTypeReceiver() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/properties/flexibleTypeReceiver.kt");
+            }
+
             @Test
             @TestMetadata("inferPropertyTypeFromGetter.kt")
             public void testInferPropertyTypeFromGetter() throws Exception {

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/dfa/VariableStorageImpl.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.fir.resolve.toSymbol
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.ConeClassLikeType
+import org.jetbrains.kotlin.fir.types.lowerBoundIfFlexible
 import org.jetbrains.kotlin.fir.types.resolvedType
 import org.jetbrains.kotlin.fir.utils.exceptions.withFirEntry
 import org.jetbrains.kotlin.fir.utils.exceptions.withFirSymbolEntry
@@ -179,8 +180,8 @@ class VariableStorageImpl(private val session: FirSession) : VariableStorage() {
             property.modality != Modality.FINAL -> {
                 val dispatchReceiver = (originalFir.unwrapElement() as? FirQualifiedAccessExpression)?.dispatchReceiver ?: return null
 
-                val receiverType = (dispatchReceiver.resolvedType as? ConeClassLikeType)?.fullyExpandedType(session) ?: return null
-                val receiverSymbol = receiverType.lookupTag.toSymbol(session) ?: return null
+                val receiverType = dispatchReceiver.resolvedType.lowerBoundIfFlexible().fullyExpandedType(session)
+                val receiverSymbol = (receiverType as? ConeClassLikeType)?.lookupTag?.toSymbol(session) ?: return null
                 when (val receiverFir = receiverSymbol.fir) {
                     is FirAnonymousObject -> PropertyStability.STABLE_VALUE
                     is FirRegularClass -> if (receiverFir.modality == Modality.FINAL) PropertyStability.STABLE_VALUE else PropertyStability.PROPERTY_WITH_GETTER

compiler/testData/diagnostics/tests/properties/flexibleTypeReceiver.kt

@@ -0,0 +1,20 @@
+// FIR_IDENTICAL
+// WITH_STDLIB
+
+// FILE: WorkAction.java
+public interface WorkAction<T> {
+    T getParameters();
+}
+
+// FILE: main.kt
+abstract class RunGTestJob : WorkAction<RunGTestJob.Parameters> {
+    interface Parameters {
+        val executable: String
+    }
+
+    fun execute() {
+        with(parameters) {
+            <!VAL_REASSIGNMENT!>executable<!> = executable
+        }
+    }
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -27916,6 +27916,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/properties/extensionPropertyMustHaveAccessorsOrBeAbstract.kt");
             }
 
+            @Test
+            @TestMetadata("flexibleTypeReceiver.kt")
+            public void testFlexibleTypeReceiver() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/properties/flexibleTypeReceiver.kt");
+            }
+
             @Test
             @TestMetadata("inferPropertyTypeFromGetter.kt")
             public void testInferPropertyTypeFromGetter() throws Exception {