[FIR/IR generator] Factor out adding pure abstract element as parent

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/AbstractElement.kt

@@ -22,7 +22,7 @@ abstract class AbstractElement<Element, Field> : ElementOrRef<Element, Field>, F
 
     abstract val elementParents: List<ElementRef<Element, Field>>
 
-    abstract val otherParents: List<ClassRef<*>>
+    abstract val otherParents: MutableList<ClassRef<*>>
 
     val parentRefs: List<ClassOrElementRef>
         get() = elementParents + otherParents

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/ImplementationKindOwner.kt

@@ -9,7 +9,3 @@ interface ImplementationKindOwner : Importable {
     var kind: ImplementationKind?
     val allParents: List<ImplementationKindOwner>
 }
-
-val ImplementationKindOwner.needPureAbstractElement: Boolean
-    get() = !(kind?.isInterface ?: false) &&
-            allParents.none { it.kind == ImplementationKind.AbstractClass || it.kind == ImplementationKind.SealedClass }

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/TypeRef.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.generators.tree
 
+import org.jetbrains.kotlin.generators.tree.printer.braces
 import org.jetbrains.kotlin.types.Variance
 import java.util.*
 import kotlin.reflect.KClass
@@ -196,3 +197,17 @@ inline fun <reified T : Any> type(vararg args: TypeRef) = T::class.asRef<Positio
 
 fun type(packageName: String, name: String, kind: TypeKind = TypeKind.Interface) =
     ClassRef<PositionTypeParameterRef>(kind, packageName, name)
+
+val ClassOrElementRef.typeKind: TypeKind
+    get() = when (this) {
+        is ElementOrRef<*, *> -> element.kind!!.typeKind
+        is ClassRef<*> -> kind
+    }
+
+fun ClassOrElementRef.inheritanceClauseParenthesis(): String = when (this) {
+    is ElementOrRef<*, *> -> element.kind.braces()
+    is ClassRef<*> -> when (kind) {
+        TypeKind.Class -> "()"
+        TypeKind.Interface -> ""
+    }
+}

generators/tree-generator-common/src/org/jetbrains/kotlin/generators/tree/addPureAbstractElement.kt

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2010-2023 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.generators.tree
+
+val ImplementationKindOwner.needPureAbstractElement: Boolean
+    get() = !(kind?.isInterface ?: false) &&
+            allParents.none { it.kind == ImplementationKind.AbstractClass || it.kind == ImplementationKind.SealedClass }
+
+fun addPureAbstractElement(elements: List<AbstractElement<*, *>>, pureAbstractElement: ClassRef<*>) {
+    for (el in elements) {
+        if (el.needPureAbstractElement) {
+            el.otherParents.add(pureAbstractElement)
+        }
+    }
+}