[FIR2IR] Extract logic of IR declarations generation into separate component. Part 15

Always require containing IrClass for enum entries

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

@@ -795,16 +795,15 @@ class Fir2IrDeclarationStorage(
         return when (val firDeclaration = firVariableSymbol.fir) {
             is FirEnumEntry -> {
                 classifierStorage.getCachedIrEnumEntry(firDeclaration)?.let { return it.symbol }
-                val irParentClass = firDeclaration.containingClassLookupTag()?.let { classifierStorage.findIrClass(it) }
+                val irParentClass = firDeclaration.containingClassLookupTag()?.let { classifierStorage.findIrClass(it) }!!
 
                 val firProviderForSymbol = firVariableSymbol.moduleData.session.firProvider
                 val containingFile = firProviderForSymbol.getFirCallableContainerFile(firVariableSymbol)
 
-                classifierStorage.createIrEnumEntry(
+                classifierStorage.getIrEnumEntry(
                     firDeclaration,
                     irParent = irParentClass,
-                    predefinedOrigin = if (containingFile != null) IrDeclarationOrigin.DEFINED else
-                        irParentClass?.origin ?: IrDeclarationOrigin.IR_EXTERNAL_DECLARATION_STUB
+                    predefinedOrigin = if (containingFile != null) IrDeclarationOrigin.DEFINED else irParentClass.origin
                 ).symbol
             }
             is FirValueParameter -> {

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/Fir2IrClassifiersGenerator.kt

@@ -385,7 +385,7 @@ class Fir2IrClassifiersGenerator(val components: Fir2IrComponents) : Fir2IrCompo
 
     fun createIrEnumEntry(
         enumEntry: FirEnumEntry,
-        irParent: IrClass?,
+        irParent: IrClass,
         predefinedOrigin: IrDeclarationOrigin? = null,
     ): IrEnumEntry {
         return enumEntry.convertWithOffsets { startOffset, endOffset ->
@@ -400,9 +400,7 @@ class Fir2IrClassifiersGenerator(val components: Fir2IrComponents) : Fir2IrCompo
                     symbol = symbol,
                 ).apply {
                     declarationStorage.enterScope(this.symbol)
-                    if (irParent != null) {
-                        this.parent = irParent
-                    }
+                    this.parent = irParent
                     if (isEnumEntryWhichRequiresSubclass(enumEntry)) {
                         // An enum entry with its own members requires an anonymous object generated.
                         // Otherwise, this is a default-ish enum entry whose initializer would be a delegating constructor call,