IR: explicitly pass isFakeOverride to buildFun and friends

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt

@@ -560,6 +560,7 @@ fun createStaticFunctionWithReceivers(
     origin: IrDeclarationOrigin = oldFunction.origin,
     modality: Modality = Modality.FINAL,
     visibility: Visibility = oldFunction.visibility,
+    isFakeOverride: Boolean = oldFunction.isFakeOverride,
     copyMetadata: Boolean = true,
     typeParametersFromContext: List<IrTypeParameter> = listOf()
 ): IrSimpleFunction {
@@ -579,7 +580,7 @@ fun createStaticFunctionWithReceivers(
         isTailrec = false,
         isSuspend = oldFunction.isSuspend,
         isExpect = oldFunction.isExpect,
-        isFakeOverride = origin == IrDeclarationOrigin.FAKE_OVERRIDE,
+        isFakeOverride = isFakeOverride,
         isOperator = oldFunction is IrSimpleFunction && oldFunction.isOperator
     ).apply {
         descriptor.bind(this)

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/DefaultArgumentStubGenerator.kt

@@ -425,7 +425,7 @@ private fun IrFunction.generateDefaultsFunction(
     if (this is IrSimpleFunction) {
         // If this is an override of a function with default arguments, produce a fake override of a default stub.
         if (overriddenSymbols.any { it.owner.findBaseFunctionWithDefaultArguments(skipInlineMethods, skipExternalMethods) != null })
-            return generateDefaultsFunctionImpl(context, IrDeclarationOrigin.FAKE_OVERRIDE, visibility).also {
+            return generateDefaultsFunctionImpl(context, IrDeclarationOrigin.FAKE_OVERRIDE, visibility, isFakeOverride = true).also {
                 context.mapping.defaultArgumentsDispatchFunction[this] = it
                 context.mapping.defaultArgumentsOriginalFunction[it] = this
 
@@ -453,7 +453,9 @@ private fun IrFunction.generateDefaultsFunction(
     // Since this bug causes the metadata serializer to write the "has default value" flag into compiled
     // binaries, it's way too late to fix it. Hence the workaround.
     if (valueParameters.any { it.defaultValue != null }) {
-        return generateDefaultsFunctionImpl(context, IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER, visibility).also {
+        return generateDefaultsFunctionImpl(
+            context, IrDeclarationOrigin.FUNCTION_FOR_DEFAULT_PARAMETER, visibility, isFakeOverride = false
+        ).also {
             context.mapping.defaultArgumentsDispatchFunction[this] = it
             context.mapping.defaultArgumentsOriginalFunction[it] = this
         }
@@ -464,7 +466,8 @@ private fun IrFunction.generateDefaultsFunction(
 private fun IrFunction.generateDefaultsFunctionImpl(
     context: CommonBackendContext,
     newOrigin: IrDeclarationOrigin,
-    newVisibility: Visibility
+    newVisibility: Visibility,
+    isFakeOverride: Boolean
 ): IrFunction {
     val newFunction = when (this) {
         is IrConstructor ->
@@ -481,6 +484,7 @@ private fun IrFunction.generateDefaultsFunctionImpl(
                 updateFrom(this@generateDefaultsFunctionImpl)
                 name = Name.identifier("${this@generateDefaultsFunctionImpl.name}\$default")
                 origin = newOrigin
+                this.isFakeOverride = isFakeOverride
                 modality = Modality.FINAL
                 isExternal = false
                 isTailrec = false

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/LateinitLowering.kt

@@ -213,4 +213,4 @@ private fun CommonBackendContext.buildOrGetNullableField(originalField: IrField)
     }
 }
 
-private val IrProperty.isRealLateinit get() = isLateinit && getter?.isFakeOverride != true
+private val IrProperty.isRealLateinit get() = isLateinit && !isFakeOverride

compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/builders/declarations/declarationBuilders.kt

@@ -44,8 +44,7 @@ fun IrFieldBuilder.buildField(): IrField {
     return IrFieldImpl(
         startOffset, endOffset, origin,
         IrFieldSymbolImpl(wrappedDescriptor),
-        name, type, visibility, isFinal, isExternal, isStatic,
-        origin == IrDeclarationOrigin.FAKE_OVERRIDE
+        name, type, visibility, isFinal, isExternal, isStatic, isFakeOverride
     ).also {
         it.metadata = metadata
         wrappedDescriptor.bind(it)
@@ -81,7 +80,7 @@ fun IrPropertyBuilder.buildProperty(): IrProperty {
         IrPropertySymbolImpl(wrappedDescriptor),
         name, visibility, modality,
         isVar = isVar, isConst = isConst, isLateinit = isLateinit, isDelegated = isDelegated, isExpect = isExpect, isExternal = isExternal,
-        isFakeOverride = origin == IrDeclarationOrigin.FAKE_OVERRIDE
+        isFakeOverride = isFakeOverride
     ).also {
         wrappedDescriptor.bind(it)
     }
@@ -133,8 +132,7 @@ fun IrFunctionBuilder.buildFun(originalDescriptor: FunctionDescriptor? = null):
         IrSimpleFunctionSymbolImpl(wrappedDescriptor),
         name, visibility, modality, returnType,
         isInline = isInline, isExternal = isExternal, isTailrec = isTailrec, isSuspend = isSuspend, isExpect = isExpect,
-        isFakeOverride = origin == IrDeclarationOrigin.FAKE_OVERRIDE,
-        isOperator = isOperator
+        isFakeOverride = isFakeOverride, isOperator = isOperator
     ).also {
         wrappedDescriptor.bind(it)
     }
@@ -183,6 +181,7 @@ fun IrDeclarationContainer.addFunction(
     visibility: Visibility = Visibilities.PUBLIC,
     isStatic: Boolean = false,
     isSuspend: Boolean = false,
+    isFakeOverride: Boolean = false,
     origin: IrDeclarationOrigin = IrDeclarationOrigin.DEFINED
 ): IrSimpleFunction =
     addFunction {
@@ -191,6 +190,7 @@ fun IrDeclarationContainer.addFunction(
         this.modality = modality
         this.visibility = visibility
         this.isSuspend = isSuspend
+        this.isFakeOverride = isFakeOverride
         this.origin = origin
     }.apply {
         if (!isStatic) {