[FIR2IR] Don't generate fake overrides for clashing synthetic properties

If a synthetic prop clashes with a real property (e.g. @JvmField
property from parent Kotlin class), don't generate fake override for the
synthetic property. This fixes a CONFLICTING_INHERITED_JVM_DECLARATIONS
error in a mixed hierarchy.

^KT-56538 Fixed

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/FakeOverrideGenerator.kt

@@ -83,12 +83,17 @@ class FakeOverrideGenerator(
             // This parameter is only needed for data-class methods that is irrelevant for lazy library classes
             realDeclarationSymbols = emptySet()
         )
-        FirSyntheticPropertiesScope.createIfSyntheticNamesProviderIsDefined(session, firClass.defaultType(), useSiteMemberScope)?.let {
-            generateFakeOverridesForName(
-                irClass, it, name, firClass, this,
-                // This parameter is only needed for data-class methods that is irrelevant for lazy library classes
-                realDeclarationSymbols = emptySet()
-            )
+        // Only add synthetic properties if no real properties were found. This can happen in a mixed hierarchy when a Java class
+        // inherits an @JvmField property. When a Kotlin class extends that Java class, CONFLICTING_INHERITED_JVM_DECLARATIONS will be
+        // reported otherwise. See KT-56538.
+        if (none { it is IrProperty }) {
+            FirSyntheticPropertiesScope.createIfSyntheticNamesProviderIsDefined(session, firClass.defaultType(), useSiteMemberScope)?.let {
+                generateFakeOverridesForName(
+                    irClass, it, name, firClass, this,
+                    // This parameter is only needed for data-class methods that is irrelevant for lazy library classes
+                    realDeclarationSymbols = emptySet()
+                )
+            }
         }
         if (firClass.isEnumClass) return@buildList // F/O for values/valueOf/entries aren't needed, for other members aren't possible
         val staticScope = firClass.scopeProvider.getStaticMemberScopeForCallables(firClass, session, scopeSession)

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -28827,6 +28827,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/javaInterop/superCallOfPrintStackTrace.kt");
         }
 
+        @Test
+        @TestMetadata("syntheticPropClashingWithJvmField.kt")
+        public void testSyntheticPropClashingWithJvmField() throws Exception {
+            runTest("compiler/testData/codegen/box/javaInterop/syntheticPropClashingWithJvmField.kt");
+        }
+
         @Test
         @TestMetadata("unresolvedJavaClassInDifferentFile.kt")
         public void testUnresolvedJavaClassInDifferentFile() throws Exception {

compiler/testData/codegen/box/javaInterop/syntheticPropClashingWithJvmField.kt

@@ -0,0 +1,33 @@
+// TARGET_BACKEND: JVM
+// WITH_STDLIB
+// ISSUE: KT-56538
+
+// FILE: SerializableScheme.java
+
+public interface SerializableScheme {
+    String getSchemeState();
+}
+
+// FILE: NewInspectionProfile.kt
+
+abstract class NewInspectionProfile : SerializableScheme {
+    @JvmField
+    internal var schemeState: String? = "OK"
+
+    override fun getSchemeState(): String? = schemeState
+}
+
+// FILE: InspectionProfileImpl.java
+
+public class InspectionProfileImpl extends NewInspectionProfile {
+}
+
+// FILE: InspectionProfileModifiableModel.kt
+
+class InspectionProfileModifiableModel : InspectionProfileImpl()
+
+// FILE: test.kt
+
+fun box(): String {
+    return InspectionProfileModifiableModel().schemeState.toString()
+}

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

@@ -27585,6 +27585,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/javaInterop/superCallOfPrintStackTrace.kt");
         }
 
+        @Test
+        @TestMetadata("syntheticPropClashingWithJvmField.kt")
+        public void testSyntheticPropClashingWithJvmField() throws Exception {
+            runTest("compiler/testData/codegen/box/javaInterop/syntheticPropClashingWithJvmField.kt");
+        }
+
         @Test
         @TestMetadata("unresolvedJavaClassInDifferentFile.kt")
         public void testUnresolvedJavaClassInDifferentFile() throws Exception {

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

@@ -28827,6 +28827,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/javaInterop/superCallOfPrintStackTrace.kt");
         }
 
+        @Test
+        @TestMetadata("syntheticPropClashingWithJvmField.kt")
+        public void testSyntheticPropClashingWithJvmField() throws Exception {
+            runTest("compiler/testData/codegen/box/javaInterop/syntheticPropClashingWithJvmField.kt");
+        }
+
         @Test
         @TestMetadata("unresolvedJavaClassInDifferentFile.kt")
         public void testUnresolvedJavaClassInDifferentFile() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -23283,6 +23283,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/javaInterop/superCallOfPrintStackTrace.kt");
         }
 
+        @TestMetadata("syntheticPropClashingWithJvmField.kt")
+        public void testSyntheticPropClashingWithJvmField() throws Exception {
+            runTest("compiler/testData/codegen/box/javaInterop/syntheticPropClashingWithJvmField.kt");
+        }
+
         @TestMetadata("unresolvedJavaClassInDifferentFile.kt")
         public void testUnresolvedJavaClassInDifferentFile() throws Exception {
             runTest("compiler/testData/codegen/box/javaInterop/unresolvedJavaClassInDifferentFile.kt");