FIR2IR: Fix signature computed for fake-overrides

Take into account _new owner_ of the function
Namely, if there's a substitution override from a class A<T> in its subtype B,
it will refer `B` as its owner in the signature

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt

@@ -394,7 +394,8 @@ class Fir2IrDeclarationStorage(
         irParent: IrDeclarationParent?,
         thisReceiverOwner: IrClass? = irParent as? IrClass,
         origin: IrDeclarationOrigin = IrDeclarationOrigin.DEFINED,
-        isLocal: Boolean = false
+        isLocal: Boolean = false,
+        containingClass: ConeClassLikeLookupTag? = null,
     ): IrSimpleFunction {
         val simpleFunction = function as? FirSimpleFunction
         val isLambda = function.source?.elementType == KtNodeTypes.FUNCTION_LITERAL
@@ -411,7 +412,7 @@ class Fir2IrDeclarationStorage(
         val isSuspend =
             if (isLambda) ((function as FirAnonymousFunction).typeRef as? FirResolvedTypeRef)?.type?.isSuspendFunctionType(session) == true
             else simpleFunction?.isSuspend == true
-        val signature = if (isLocal) null else signatureComposer.composeSignature(function)
+        val signature = if (isLocal) null else signatureComposer.composeSignature(function, containingClass)
         val created = function.convertWithOffsets { startOffset, endOffset ->
             val result = declareIrSimpleFunction(signature, simpleFunction?.containerSource) { symbol ->
                 irFactory.createFunction(
@@ -534,10 +535,11 @@ class Fir2IrDeclarationStorage(
         origin: IrDeclarationOrigin,
         startOffset: Int,
         endOffset: Int,
-        isLocal: Boolean = false
+        isLocal: Boolean = false,
+        containingClass: ConeClassLikeLookupTag? = null,
     ): IrSimpleFunction {
         val prefix = if (isSetter) "set" else "get"
-        val signature = if (isLocal) null else signatureComposer.composeAccessorSignature(property, isSetter)
+        val signature = if (isLocal) null else signatureComposer.composeAccessorSignature(property, isSetter, containingClass)
         val containerSource = (correspondingProperty as? IrProperty)?.containerSource
         return declareIrAccessor(
             signature,
@@ -655,10 +657,11 @@ class Fir2IrDeclarationStorage(
         irParent: IrDeclarationParent?,
         thisReceiverOwner: IrClass? = irParent as? IrClass,
         origin: IrDeclarationOrigin = IrDeclarationOrigin.DEFINED,
-        isLocal: Boolean = false
+        isLocal: Boolean = false,
+        containingClass: ConeClassLikeLookupTag? = null,
     ): IrProperty {
         classifierStorage.preCacheTypeParameters(property)
-        val signature = if (isLocal) null else signatureComposer.composeSignature(property)
+        val signature = if (isLocal) null else signatureComposer.composeSignature(property, containingClass)
         return property.convertWithOffsets { startOffset, endOffset ->
             val result = declareIrProperty(signature, property.containerSource) { symbol ->
                 irFactory.createProperty(
@@ -719,7 +722,7 @@ class Fir2IrDeclarationStorage(
                             getter is FirDefaultPropertyGetter -> IrDeclarationOrigin.DEFAULT_PROPERTY_ACCESSOR
                             else -> origin
                         },
-                        startOffset, endOffset, isLocal
+                        startOffset, endOffset, isLocal, containingClass
                     )
                     if (property.isVar) {
                         this.setter = createIrPropertyAccessor(
@@ -729,7 +732,7 @@ class Fir2IrDeclarationStorage(
                                 setter is FirDefaultPropertySetter -> IrDeclarationOrigin.DEFAULT_PROPERTY_ACCESSOR
                                 else -> origin
                             },
-                            startOffset, endOffset, isLocal
+                            startOffset, endOffset, isLocal, containingClass
                         )
                     }
                     leaveScope(this)

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrSignatureComposer.kt

@@ -7,9 +7,10 @@ package org.jetbrains.kotlin.fir.backend
 
 import org.jetbrains.kotlin.fir.declarations.FirDeclaration
 import org.jetbrains.kotlin.fir.declarations.FirProperty
+import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
 import org.jetbrains.kotlin.ir.util.IdSignature
 
 interface Fir2IrSignatureComposer {
-    fun composeSignature(declaration: FirDeclaration): IdSignature?
+    fun composeSignature(declaration: FirDeclaration, containingClass: ConeClassLikeLookupTag? = null): IdSignature?
-    fun composeAccessorSignature(property: FirProperty, isSetter: Boolean): IdSignature?
+    fun composeAccessorSignature(property: FirProperty, isSetter: Boolean, containingClass: ConeClassLikeLookupTag? = null): IdSignature?
 }

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/signaturer/FirBasedSignatureComposer.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.fir.backend.Fir2IrSignatureComposer
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.render
 import org.jetbrains.kotlin.fir.symbols.CallableId
+import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
 import org.jetbrains.kotlin.fir.visitors.FirVisitorVoid
 import org.jetbrains.kotlin.ir.util.IdSignature
 import org.jetbrains.kotlin.name.FqName
@@ -62,11 +63,11 @@ class FirBasedSignatureComposer(private val mangler: FirMangler) : Fir2IrSignatu
     private val CallableId.relativeCallableName: FqName
         get() = className?.child(callableName) ?: FqName.topLevel(callableName)
 
-    override fun composeSignature(declaration: FirDeclaration): IdSignature? {
+    override fun composeSignature(declaration: FirDeclaration, containingClass: ConeClassLikeLookupTag?): IdSignature? {
         if (declaration is FirAnonymousObject || declaration is FirAnonymousFunction) return null
         if (declaration is FirRegularClass && declaration.classId.isLocal) return null
         if (declaration is FirCallableMemberDeclaration<*>) {
-            if (declaration.visibility == Visibilities.Local || declaration.symbol.callableId.classId?.isLocal == true) return null
+            if (declaration.visibility == Visibilities.Local || declaration.symbol.callableId.classId?.isLocal == true || containingClass?.classId?.isLocal == true) return null
         }
         val builder = SignatureBuilder()
         try {
@@ -91,7 +92,10 @@ class FirBasedSignatureComposer(private val mangler: FirMangler) : Fir2IrSignatu
             }
             is FirCallableMemberDeclaration<*> -> {
                 if (declaration.visibility == Visibilities.Private) return null
-                val callableId = declaration.symbol.callableId
+                val containingClassId = containingClass?.classId
+                val baseCallableId = declaration.symbol.callableId
+                val callableId =
+                    if (containingClassId != null) CallableId(containingClassId, baseCallableId.callableName) else baseCallableId
                 IdSignature.PublicSignature(
                     callableId.packageName.asString(), callableId.relativeCallableName.asString(), builder.hashId, builder.mask
                 )
@@ -100,8 +104,12 @@ class FirBasedSignatureComposer(private val mangler: FirMangler) : Fir2IrSignatu
         }
     }
 
-    override fun composeAccessorSignature(property: FirProperty, isSetter: Boolean): IdSignature? {
+    override fun composeAccessorSignature(
-        val propertySignature = composeSignature(property) as? IdSignature.PublicSignature ?: return null
+        property: FirProperty,
+        isSetter: Boolean,
+        containingClass: ConeClassLikeLookupTag?
+    ): IdSignature? {
+        val propertySignature = composeSignature(property, containingClass) as? IdSignature.PublicSignature ?: return null
         val accessorFqName = if (isSetter) {
             propertySignature.declarationFqName + ".<set-${property.name.asString()}>"
         } else {