FIR2IR: Support initialSignatureDescriptor

It will be used for overrides of renamed special built-ins during signature mapping
to obtain initial signature

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/AbstractFir2IrLazyFunction.kt

@@ -14,13 +14,18 @@ import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.symbols.Fir2IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.declarations.lazy.IrLazyFunctionBase
 import org.jetbrains.kotlin.ir.declarations.lazy.lazyVar
 import org.jetbrains.kotlin.ir.expressions.IrBody
+import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrPropertySymbol
 import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.kotlin.ir.util.DeclarationStubGenerator
+import org.jetbrains.kotlin.ir.util.TypeTranslator
 import org.jetbrains.kotlin.ir.util.isObject
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.resolve.annotations.JVM_STATIC_ANNOTATION_FQ_NAME
+import kotlin.properties.ReadWriteProperty
 
 abstract class AbstractFir2IrLazyFunction<F : FirMemberDeclaration>(
     components: Fir2IrComponents,
@@ -29,7 +34,7 @@ abstract class AbstractFir2IrLazyFunction<F : FirMemberDeclaration>(
     override var origin: IrDeclarationOrigin,
     override val symbol: Fir2IrSimpleFunctionSymbol,
     override val isFakeOverride: Boolean
-) : IrSimpleFunction(), AbstractFir2IrLazyDeclaration<F, IrSimpleFunction>, Fir2IrComponents by components {
+) : IrSimpleFunction(), AbstractFir2IrLazyDeclaration<F, IrSimpleFunction>, IrLazyFunctionBase, Fir2IrComponents by components {
 
     override lateinit var typeParameters: List<IrTypeParameter>
     override lateinit var parent: IrDeclarationParent
@@ -94,7 +99,19 @@ abstract class AbstractFir2IrLazyFunction<F : FirMemberDeclaration>(
         }
     }
 
+    override val stubGenerator: DeclarationStubGenerator
+        get() = error("Should not be called")
+    override val typeTranslator: TypeTranslator
+        get() = error("Should not be called")
+
+    override val factory: IrFactory
+        get() = super<AbstractFir2IrLazyDeclaration>.factory
+
+    override fun createLazyAnnotations(): ReadWriteProperty<Any?, List<IrConstructorCall>> {
+        return super<AbstractFir2IrLazyDeclaration>.createLazyAnnotations()
+    }
+
     companion object {
         private val JVM_STATIC_CLASS_ID = ClassId.topLevel(JVM_STATIC_ANNOTATION_FQ_NAME)
     }
-}
+}

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyPropertyAccessor.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.fir.lazy
 
 import org.jetbrains.kotlin.fir.backend.*
 import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticPropertyAccessor
 import org.jetbrains.kotlin.fir.symbols.Fir2IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.lazy.lazyVar
@@ -81,7 +82,18 @@ class Fir2IrLazyPropertyAccessor(
     }
 
     override var overriddenSymbols: List<IrSimpleFunctionSymbol> by lazyVar {
-        firParentProperty.generateOverriddenAccessorSymbols(firParentClass, !isSetter, session, scopeSession, declarationStorage)
+        firParentProperty.generateOverriddenAccessorSymbols(
+            firParentClass,
+            !isSetter,
+            session,
+            scopeSession,
+            declarationStorage,
+            fakeOverrideGenerator
+        )
+    }
+
+    override val initialSignatureFunction: IrFunction? by lazy {
+        (fir as? FirSyntheticPropertyAccessor)?.delegate?.let { declarationStorage.getIrFunctionSymbol(it.symbol).owner }
     }
 
     override val containerSource: DeserializedContainerSource?

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazySimpleFunction.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.fir.lazy
 
 import org.jetbrains.kotlin.fir.backend.*
 import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.initialSignatureAttr
 import org.jetbrains.kotlin.fir.symbols.Fir2IrSimpleFunctionSymbol
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.lazy.lazyVar
@@ -72,7 +73,11 @@ class Fir2IrLazySimpleFunction(
             parent.declarations
             fakeOverrideGenerator.getOverriddenSymbols(this)?.let { return@lazyVar it }
         }
-        fir.generateOverriddenFunctionSymbols(firParent, session, scopeSession, declarationStorage)
+        fir.generateOverriddenFunctionSymbols(firParent, session, scopeSession, declarationStorage, fakeOverrideGenerator)
+    }
+
+    override val initialSignatureFunction: IrFunction? by lazy {
+        (fir.initialSignatureAttr as? FirFunction<*>)?.symbol?.let { declarationStorage.getIrFunctionSymbol(it).owner }
     }
 
     override val containerSource: DeserializedContainerSource?

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/enhancement/SignatureEnhancement.kt

@@ -18,6 +18,7 @@ import org.jetbrains.kotlin.fir.declarations.impl.FirDeclarationStatusImpl
 import org.jetbrains.kotlin.fir.declarations.impl.FirResolvedDeclarationStatusImpl
 import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticProperty
 import org.jetbrains.kotlin.fir.declarations.synthetic.buildSyntheticProperty
+import org.jetbrains.kotlin.fir.initialSignatureAttr
 import org.jetbrains.kotlin.fir.java.JavaTypeParameterStack
 import org.jetbrains.kotlin.fir.java.declarations.*
 import org.jetbrains.kotlin.fir.render
@@ -55,7 +56,13 @@ class FirSignatureEnhancement(
         function: FirFunctionSymbol<*>,
         name: Name?
     ): FirFunctionSymbol<*> {
-        return enhancements.getOrPut(function) { enhance(function, name) } as FirFunctionSymbol<*>
+        return enhancements.getOrPut(function) {
+            enhance(function, name).also { enhancedVersion ->
+                (enhancedVersion.fir.initialSignatureAttr as? FirSimpleFunction)?.let {
+                    enhancedVersion.fir.initialSignatureAttr = enhancedFunction(it.symbol, it.name).fir
+                }
+            }
+        } as FirFunctionSymbol<*>
     }
 
     fun enhancedProperty(property: FirVariableSymbol<*>, name: Name): FirVariableSymbol<*> {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/ClassMembers.kt

@@ -70,3 +70,6 @@ var <D : FirCallableDeclaration<*>>
 private object IntersectionOverrideOriginalKey : FirDeclarationDataKey()
 var <D : FirCallableDeclaration<*>>
         D.originalForIntersectionOverrideAttr: D? by FirDeclarationDataRegistry.data(IntersectionOverrideOriginalKey)
+
+private object InitialSignatureKey : FirDeclarationDataKey()
+var FirCallableDeclaration<*>.initialSignatureAttr: FirCallableDeclaration<*>? by FirDeclarationDataRegistry.data(InitialSignatureKey)