IR: introduce IrFakeOverrideFunction, IrFakeOverrideProperty

Use them instead of the implementations. This will allow to refactor
creation to a factory and allow to use other implementations in the
future.

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrFakeOverrideFunction.kt

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.ir.declarations
+
+import org.jetbrains.kotlin.descriptors.Modality
+import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
+
+interface IrFakeOverrideFunction : IrSimpleFunction {
+    override var modality: Modality
+
+    fun acquireSymbol(symbol: IrSimpleFunctionSymbol)
+}

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrFakeOverrideProperty.kt

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.ir.declarations
+
+import org.jetbrains.kotlin.descriptors.Modality
+import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
+
+interface IrFakeOverrideProperty : IrProperty {
+    override var modality: Modality
+
+    fun acquireSymbol(symbol: IrPropertySymbol)
+}

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFunctionImpl.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.IrAttributeContainer
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
+import org.jetbrains.kotlin.ir.declarations.IrFakeOverrideFunction
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.declarations.impl.carriers.FunctionCarrier
 import org.jetbrains.kotlin.ir.descriptors.WrappedSimpleFunctionDescriptor
@@ -123,11 +124,11 @@ class IrFakeOverrideFunctionImpl(
     isSuspend: Boolean,
     isOperator: Boolean,
     isInfix: Boolean,
-    isExpect: Boolean
+    isExpect: Boolean,
-) : IrFunctionCommonImpl(startOffset, endOffset, origin, name, visibility, modality, returnType, isInline,
+) : IrFunctionCommonImpl(
-    isExternal, isTailrec, isSuspend, isOperator, isInfix, isExpect,
+    startOffset, endOffset, origin, name, visibility, modality, returnType, isInline,
-    isFakeOverride = true)
+    isExternal, isTailrec, isSuspend, isOperator, isInfix, isExpect, isFakeOverride = true
-{
+), IrFakeOverrideFunction {
     private var _symbol: IrSimpleFunctionSymbol? = null
 
     override val symbol: IrSimpleFunctionSymbol
@@ -138,7 +139,7 @@ class IrFakeOverrideFunctionImpl(
         get() = _symbol?.descriptor ?: WrappedSimpleFunctionDescriptor()
 
     @OptIn(ObsoleteDescriptorBasedAPI::class)
-    fun acquireSymbol(symbol: IrSimpleFunctionSymbol) {
+    override fun acquireSymbol(symbol: IrSimpleFunctionSymbol) {
         assert(_symbol == null) { "$this already has symbol _symbol" }
         _symbol = symbol
         symbol.bind(this)

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrPropertyImpl.kt

@@ -145,9 +145,10 @@ class IrFakeOverridePropertyImpl(
     isDelegated: Boolean,
     isExternal: Boolean,
     isExpect: Boolean,
-) : IrPropertyCommonImpl(startOffset, endOffset, origin, name, visibility, modality, isVar, isConst, isLateinit,
+) : IrPropertyCommonImpl(
-    isDelegated, isExternal, isExpect, isFakeOverride = true)
+    startOffset, endOffset, origin, name, visibility, modality, isVar, isConst, isLateinit,
-{
+    isDelegated, isExternal, isExpect, isFakeOverride = true
+), IrFakeOverrideProperty {
     private var _symbol: IrPropertySymbol? = null
 
     override val symbol: IrPropertySymbol
@@ -158,7 +159,7 @@ class IrFakeOverridePropertyImpl(
         get() = _symbol?.descriptor ?: WrappedPropertyDescriptor()
 
     @OptIn(ObsoleteDescriptorBasedAPI::class)
-    fun acquireSymbol(symbol: IrPropertySymbol) {
+    override fun acquireSymbol(symbol: IrPropertySymbol) {
         assert(_symbol == null) { "$this already has symbol _symbol" }
         _symbol = symbol
         symbol.bind(this)

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/overrides/FakeOverrides.kt

@@ -18,11 +18,7 @@ package org.jetbrains.kotlin.backend.common.overrides
 
 import org.jetbrains.kotlin.backend.common.serialization.signature.IdSignatureSerializer
 import org.jetbrains.kotlin.ir.IrElement
-import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.declarations.IrFunction
-import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
-import org.jetbrains.kotlin.ir.declarations.IrOverridableMember
-import org.jetbrains.kotlin.ir.declarations.impl.IrFakeOverrideFunctionImpl
 import org.jetbrains.kotlin.ir.declarations.impl.IrFakeOverridePropertyImpl
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.descriptors.WrappedPropertyDescriptor
@@ -118,13 +114,13 @@ class FakeOverrideBuilder(
 
     override fun linkFakeOverride(fakeOverride: IrOverridableMember) {
         when (fakeOverride) {
-            is IrFakeOverrideFunctionImpl -> linkFunctionFakeOverride(fakeOverride)
+            is IrFakeOverrideFunction -> linkFunctionFakeOverride(fakeOverride)
-            is IrFakeOverridePropertyImpl -> linkPropertyFakeOverride(fakeOverride)
+            is IrFakeOverrideProperty -> linkPropertyFakeOverride(fakeOverride)
             else -> error("Unexpected fake override: $fakeOverride")
         }
     }
 
-    private fun linkFunctionFakeOverride(declaration: IrFakeOverrideFunctionImpl) {
+    private fun linkFunctionFakeOverride(declaration: IrFakeOverrideFunction) {
         val signature = signaturer.composePublicIdSignature(declaration)
 
         symbolTable.declareSimpleFunctionFromLinker(WrappedSimpleFunctionDescriptor(), signature) {
@@ -133,7 +129,7 @@ class FakeOverrideBuilder(
         }
     }
 
-    private fun linkPropertyFakeOverride(declaration: IrFakeOverridePropertyImpl) {
+    private fun linkPropertyFakeOverride(declaration: IrFakeOverrideProperty) {
         // To compute a signature for a property with type parameters,
         // we must have its accessor's correspondingProperty pointing to the property's symbol.
         // See IrMangleComputer.mangleTypeParameterReference() for details.
@@ -159,15 +155,11 @@ class FakeOverrideBuilder(
 
         declaration.getter?.let {
             it.correspondingPropertySymbol = declaration.symbol
-            linkFunctionFakeOverride(it as? IrFakeOverrideFunctionImpl
+            linkFunctionFakeOverride(it as? IrFakeOverrideFunction ?: error("Unexpected fake override getter: $it"))
-                ?: error("Unexpected fake override getter: $it")
-            )
         }
         declaration.setter?.let {
             it.correspondingPropertySymbol = declaration.symbol
-            linkFunctionFakeOverride(it as? IrFakeOverrideFunctionImpl
+            linkFunctionFakeOverride(it as? IrFakeOverrideFunction ?: error("Unexpected fake override setter: $it"))
-                ?: error("Unexpected fake override setter: $it")
-            )
         }
     }
 

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/overrides/IrOverridingUtil.kt

@@ -21,7 +21,6 @@ import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.declarations.impl.IrFakeOverrideFunctionImpl
 import org.jetbrains.kotlin.ir.declarations.impl.IrFakeOverridePropertyImpl
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
@@ -280,7 +279,7 @@ class IrOverridingUtil(
     }
 
     private fun IrSimpleFunction.updateAccessorModalityAndVisibility(newModality: Modality, newVisibility: Visibility): IrSimpleFunction? {
-        require(this is IrFakeOverrideFunctionImpl) {
+        require(this is IrFakeOverrideFunction) {
             "Unexpected fake override accessor kind: $this"
         }
         // For descriptors it gets INVISIBLE_FAKE.
@@ -307,13 +306,13 @@ class IrOverridingUtil(
 
         val fakeOverride = mostSpecific.apply {
             when (this) {
-                is IrFakeOverridePropertyImpl -> {
+                is IrFakeOverrideProperty -> {
                     this.visibility = visibility
                     this.modality = modality
                     this.getter = this.getter?.updateAccessorModalityAndVisibility(modality, visibility)
                     this.setter = this.setter?.updateAccessorModalityAndVisibility(modality, visibility)
                 }
-                is IrFakeOverrideFunctionImpl -> {
+                is IrFakeOverrideFunction -> {
                     this.visibility = visibility
                     this.modality = modality
                 }