FIR2IR: delay generation of delegated member bodies

Before this commit, we generated delegated member bodies eagerly
at the moment when delegated member itself was generated.
However, in fact delegated member may access e.g. fake override inside
its body, so to work properly, we must delay body generation.

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrConverter.kt

@@ -103,6 +103,7 @@ class Fir2IrConverter(
 
         //   5. Body processing
         //   If we encounter local class / anonymous object here, then we perform all (1)-(5) stages immediately
+        delegatedMemberGenerator.generateBodies()
         for (firFile in allFirFiles) {
             firFile.accept(fir2irVisitor, null)
         }

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

@@ -30,6 +30,7 @@ import org.jetbrains.kotlin.fir.lazy.Fir2IrLazyConstructor
 import org.jetbrains.kotlin.fir.lazy.Fir2IrLazyProperty
 import org.jetbrains.kotlin.fir.lazy.Fir2IrLazySimpleFunction
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
+import org.jetbrains.kotlin.fir.resolve.dfa.cfg.isLocalClassOrAnonymousObject
 import org.jetbrains.kotlin.fir.types.isSuspendFunctionType
 import org.jetbrains.kotlin.fir.resolve.isKFunctionInvoke
 import org.jetbrains.kotlin.fir.resolve.providers.firProvider
@@ -949,7 +950,10 @@ class Fir2IrDeclarationStorage(
     fun createIrFieldAndDelegatedMembers(field: FirField, owner: FirClass, irClass: IrClass): IrField {
         val irField = createIrField(field, origin = IrDeclarationOrigin.DELEGATE)
         irField.setAndModifyParent(irClass)
-        components.delegatedMemberGenerator.generate(irField, field, owner, irClass)
+        delegatedMemberGenerator.generate(irField, field, owner, irClass)
+        if (owner.isLocalClassOrAnonymousObject()) {
+            delegatedMemberGenerator.generateBodies()
+        }
         return irField
     }
 

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/DelegatedMemberGenerator.kt

@@ -50,6 +50,40 @@ class DelegatedMemberGenerator(
     private val baseFunctionSymbols = mutableMapOf<IrFunction, List<FirNamedFunctionSymbol>>()
     private val basePropertySymbols = mutableMapOf<IrProperty, List<FirPropertySymbol>>()
 
+    private data class DeclarationBodyInfo(
+        val declaration: IrDeclaration,
+        val field: IrField,
+        val delegateToSymbol: FirCallableSymbol<*>
+    )
+
+    private val bodiesInfo = mutableListOf<DeclarationBodyInfo>()
+
+    fun generateBodies() {
+        for ((declaration, irField, delegateToSymbol) in bodiesInfo) {
+            when (declaration) {
+                is IrSimpleFunction -> {
+                    val member = declarationStorage.getIrFunctionSymbol(
+                        delegateToSymbol as FirNamedFunctionSymbol
+                    ).owner as? IrSimpleFunction ?: continue
+                    val body = createDelegateBody(irField, declaration, member)
+                    declaration.body = body
+                }
+                is IrProperty -> {
+                    val member = declarationStorage.getIrPropertySymbol(
+                        delegateToSymbol as FirPropertySymbol
+                    ).owner as? IrProperty ?: continue
+                    val getter = declaration.getter!!
+                    getter.body = createDelegateBody(irField, getter, member.getter!!)
+                    if (declaration.isVar) {
+                        val setter = declaration.setter!!
+                        setter.body = createDelegateBody(irField, setter, member.setter!!)
+                    }
+                }
+            }
+        }
+        bodiesInfo.clear()
+    }
+
     // Generate delegated members for [subClass]. The synthetic field [irField] has the super interface type.
     fun generate(irField: IrField, firField: FirField, firSubClass: FirClass, subClass: IrClass) {
         val subClassLookupTag = firSubClass.symbol.toLookupTag()
@@ -61,18 +95,14 @@ class DelegatedMemberGenerator(
                     .unwrapDelegateTarget(subClassLookupTag, firField)
                     ?: return@processAllFunctions
 
-            val member =
-                declarationStorage.getIrFunctionSymbol(unwrapped.symbol).owner as? IrSimpleFunction
-                    ?: return@processAllFunctions
-
             if (shouldSkipDelegationFor(unwrapped)) {
                 return@processAllFunctions
             }
 
             val irSubFunction = generateDelegatedFunction(
-                subClass, firSubClass, irField, member, functionSymbol.fir
+                subClass, firSubClass, functionSymbol.fir
             )
-
+            bodiesInfo += DeclarationBodyInfo(irSubFunction, irField, unwrapped.symbol)
             declarationStorage.cacheDelegationFunction(functionSymbol.fir, irSubFunction)
             subClass.addMember(irSubFunction)
         }
@@ -85,17 +115,14 @@ class DelegatedMemberGenerator(
                     .unwrapDelegateTarget(subClassLookupTag, firField)
                     ?: return@processAllProperties
 
-            val member = declarationStorage.getIrPropertySymbol(unwrapped.symbol).owner as? IrProperty
-                ?: return@processAllProperties
-
             if (shouldSkipDelegationFor(unwrapped)) {
                 return@processAllProperties
             }
 
             val irSubProperty = generateDelegatedProperty(
-                subClass, firSubClass, irField, member, propertySymbol.fir
+                subClass, firSubClass, propertySymbol.fir
             )
-
+            bodiesInfo += DeclarationBodyInfo(irSubProperty, irField, unwrapped.symbol)
             declarationStorage.cacheDelegatedProperty(propertySymbol.fir, irSubProperty)
             subClass.addMember(irSubProperty)
         }
@@ -146,8 +173,6 @@ class DelegatedMemberGenerator(
     private fun generateDelegatedFunction(
         subClass: IrClass,
         firSubClass: FirClass,
-        irField: IrField,
-        superFunction: IrSimpleFunction,
         delegateOverride: FirSimpleFunction
     ): IrSimpleFunction {
         val delegateFunction =
@@ -164,8 +189,6 @@ class DelegatedMemberGenerator(
         baseFunctionSymbols[delegateFunction] = baseSymbols
         annotationGenerator.generate(delegateFunction, delegateOverride)
 
-        val body = createDelegateBody(irField, delegateFunction, superFunction)
-        delegateFunction.body = body
         return delegateFunction
     }
 
@@ -226,8 +249,6 @@ class DelegatedMemberGenerator(
     private fun generateDelegatedProperty(
         subClass: IrClass,
         firSubClass: FirClass,
-        irField: IrField,
-        superProperty: IrProperty,
         firDelegateProperty: FirProperty
     ): IrProperty {
         val delegateProperty =
@@ -244,8 +265,8 @@ class DelegatedMemberGenerator(
         basePropertySymbols[delegateProperty] = baseSymbols
         annotationGenerator.generate(delegateProperty, firDelegateProperty)
 
-        delegateProperty.getter!!.body = createDelegateBody(irField, delegateProperty.getter!!, superProperty.getter!!)
-        delegateProperty.getter!!.overriddenSymbols =
+        val getter = delegateProperty.getter!!
+        getter.overriddenSymbols =
             firDelegateProperty.generateOverriddenAccessorSymbols(
                 firSubClass,
                 isGetter = true,
@@ -256,8 +277,8 @@ class DelegatedMemberGenerator(
             )
         annotationGenerator.generate(delegateProperty.getter!!, firDelegateProperty)
         if (delegateProperty.isVar) {
-            delegateProperty.setter!!.body = createDelegateBody(irField, delegateProperty.setter!!, superProperty.setter!!)
-            delegateProperty.setter!!.overriddenSymbols =
+            val setter = delegateProperty.setter!!
+            setter.overriddenSymbols =
                 firDelegateProperty.generateOverriddenAccessorSymbols(
                     firSubClass, isGetter = false, session, scopeSession, declarationStorage, fakeOverrideGenerator
                 )