FIR: Fix serialization of delegated members

^KT-47413 Relates

compiler/fir/fir-serialization/src/org/jetbrains/kotlin/fir/serialization/FirElementSerializer.kt

@@ -27,14 +27,15 @@ import org.jetbrains.kotlin.fir.resolve.calls.varargElementType
 import org.jetbrains.kotlin.fir.resolve.inference.isSuspendFunctionType
 import org.jetbrains.kotlin.fir.resolve.inference.suspendFunctionTypeToFunctionTypeWithContinuation
 import org.jetbrains.kotlin.fir.scopes.FakeOverrideTypeCalculator
+import org.jetbrains.kotlin.fir.scopes.impl.delegatedWrapperData
 import org.jetbrains.kotlin.fir.scopes.processAllFunctions
 import org.jetbrains.kotlin.fir.scopes.processAllProperties
 import org.jetbrains.kotlin.fir.serialization.constant.EnumValue
 import org.jetbrains.kotlin.fir.serialization.constant.IntValue
 import org.jetbrains.kotlin.fir.serialization.constant.StringValue
 import org.jetbrains.kotlin.fir.serialization.constant.toConstantValue
-import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirIntersectionCallableSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
 import org.jetbrains.kotlin.fir.types.impl.FirImplicitNullableAnyTypeRef
@@ -48,6 +49,7 @@ import org.jetbrains.kotlin.metadata.serialization.MutableVersionRequirementTabl
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.resolve.RequireKotlinConstants
 import org.jetbrains.kotlin.serialization.deserialization.ProtoEnumFlags
 import org.jetbrains.kotlin.types.AbstractTypeApproximator
@@ -221,7 +223,29 @@ class FirElementSerializer private constructor(
 
         fun addDeclarationIfNeeded(symbol: FirCallableSymbol<*>) {
             val declaration = symbol.fir as? FirCallableMemberDeclaration<*> ?: return
-            if (declaration.isSubstitutionOrIntersectionOverride) return
+            if (declaration.isIntersectionOverride) {
+                // This part is a kind of hack for case like
+                //
+                // interface A {
+                //    fun foo(): String?
+                // }
+                //
+                // interface B : A {
+                //     override fun foo(): String?
+                // }
+                //
+                // abstract class C(a: A) : B, A by a
+                // We should serialize C::foo as it works almost like real declarations, but currently it's hidden behind intersection scope
+                // UseSiteScope(C) = DeclaredScope(C) + FirIntersectionScope(UseSiteScope(B), DelegatedScope(a))
+                //
+                // That should be fixed by putting delegated members closer to declared scope
+                // See KT-47413
+                (declaration.symbol as? FirIntersectionCallableSymbol)?.intersections?.firstOrNull {
+                    it.fir.delegatedWrapperData != null
+                }?.let(::addDeclarationIfNeeded)
+                return
+            }
+            if (declaration.isSubstitutionOverride) return
 
             // non-intersection or substitution fake override
             if (!declaration.isStatic && declaration.dispatchReceiverClassOrNull() != this@declarations.symbol.toLookupTag()) return

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

@@ -13778,6 +13778,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/delegation/diamond2.kt");
         }
 
+        @Test
+        @TestMetadata("differentModules.kt")
+        public void testDifferentModules() throws Exception {
+            runTest("compiler/testData/codegen/box/delegation/differentModules.kt");
+        }
+
         @Test
         @TestMetadata("genericProperty.kt")
         public void testGenericProperty() throws Exception {

compiler/testData/codegen/box/delegation/differentModules.kt

@@ -0,0 +1,28 @@
+// TARGET_BACKEND: JVM
+// WITH_RUNTIME
+
+// MODULE: base
+// FILE: base.kt
+
+interface PsiClass {
+    fun foo(): String?
+}
+
+interface UClass : PsiClass {
+    override fun foo(): String?
+}
+
+abstract class BaseKotlinUClass(
+    psi: PsiClass,
+) : UClass, PsiClass by psi
+
+// MODULE: main(base)
+// FILE: main.kt
+
+class A(psi: PsiClass) : BaseKotlinUClass(psi)
+
+fun bar(uClass: UClass): String = uClass.foo()!!
+
+fun box(): String = bar(A(object : PsiClass {
+    override fun foo(): String? = "OK"
+}))

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

@@ -13778,6 +13778,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/delegation/diamond2.kt");
         }
 
+        @Test
+        @TestMetadata("differentModules.kt")
+        public void testDifferentModules() throws Exception {
+            runTest("compiler/testData/codegen/box/delegation/differentModules.kt");
+        }
+
         @Test
         @TestMetadata("genericProperty.kt")
         public void testGenericProperty() throws Exception {

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

@@ -13778,6 +13778,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/delegation/diamond2.kt");
         }
 
+        @Test
+        @TestMetadata("differentModules.kt")
+        public void testDifferentModules() throws Exception {
+            runTest("compiler/testData/codegen/box/delegation/differentModules.kt");
+        }
+
         @Test
         @TestMetadata("genericProperty.kt")
         public void testGenericProperty() throws Exception {

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

@@ -11219,6 +11219,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/delegation/diamond2.kt");
         }
 
+        @TestMetadata("differentModules.kt")
+        public void testDifferentModules() throws Exception {
+            runTest("compiler/testData/codegen/box/delegation/differentModules.kt");
+        }
+
         @TestMetadata("genericProperty.kt")
         public void testGenericProperty() throws Exception {
             runTest("compiler/testData/codegen/box/delegation/genericProperty.kt");