[IR] Refactor: extract util methods from IrExpectActualAnnotationMatchingChecker

They will be re-used in new checker in subsequent commit.

^KT-59940

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/actualizer/checker/IrExpectActualAnnotationMatchingChecker.kt

@@ -5,17 +5,12 @@
 
 package org.jetbrains.kotlin.backend.common.actualizer.checker
 
-import org.jetbrains.kotlin.backend.common.actualizer.ClassActualizationInfo
 import org.jetbrains.kotlin.backend.common.actualizer.reportActualAnnotationsNotMatchExpect
-import org.jetbrains.kotlin.backend.common.lower.parents
 import org.jetbrains.kotlin.config.LanguageFeature
-import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
-import org.jetbrains.kotlin.ir.symbols.IrTypeAliasSymbol
 import org.jetbrains.kotlin.ir.symbols.IrTypeParameterSymbol
-import org.jetbrains.kotlin.ir.util.classIdOrFail
 import org.jetbrains.kotlin.ir.util.isFakeOverride
 import org.jetbrains.kotlin.resolve.calls.mpp.AbstractExpectActualAnnotationMatchChecker
 
@@ -36,7 +31,7 @@ internal object IrExpectActualAnnotationMatchingChecker : IrExpectActualChecker
             val incompatibility =
                 AbstractExpectActualAnnotationMatchChecker.areAnnotationsCompatible(expectSymbol, actualSymbol, matchingContext) ?: continue
 
-            val reportOn = getTypealiasSymbolIfActualizedViaTypealias(expectSymbol, classActualizationInfo)
+            val reportOn = getTypealiasSymbolIfActualizedViaTypealias(expectSymbol.owner as IrDeclaration, classActualizationInfo)
                 ?: getContainingActualClassIfFakeOverride(actualSymbol)
                 ?: actualSymbol
             diagnosticsReporter.reportActualAnnotationsNotMatchExpect(
@@ -51,25 +46,10 @@ internal object IrExpectActualAnnotationMatchingChecker : IrExpectActualChecker
     private val IrSymbol.isFakeOverride: Boolean
         get() = (owner as IrDeclaration).isFakeOverride
 
-    private fun getTypealiasSymbolIfActualizedViaTypealias(
-        expectSymbol: IrSymbol,
-        classActualizationInfo: ClassActualizationInfo,
-    ): IrTypeAliasSymbol? {
-        val topLevelExpectClass = getContainingTopLevelClass(expectSymbol) ?: return null
-        val classId = topLevelExpectClass.classIdOrFail
-        return classActualizationInfo.actualTypeAliases[classId]
-    }
-
     private fun getContainingActualClassIfFakeOverride(actualSymbol: IrSymbol): IrSymbol? {
         if (!actualSymbol.isFakeOverride) {
             return null
         }
-        return getContainingTopLevelClass(actualSymbol)?.symbol
-    }
-
-    private fun getContainingTopLevelClass(symbol: IrSymbol): IrClass? {
-        val declaration = symbol.owner as IrDeclaration
-        val parentsWithSelf = sequenceOf(declaration) + declaration.parents
-        return parentsWithSelf.filterIsInstance<IrClass>().lastOrNull()
+        return getContainingTopLevelClass(actualSymbol.owner as IrDeclaration)?.symbol
     }
 }

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/actualizer/checker/irExpectActualCheckersUtils.kt

@@ -0,0 +1,27 @@
+/*
+ * 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.backend.common.actualizer.checker
+
+import org.jetbrains.kotlin.backend.common.actualizer.ClassActualizationInfo
+import org.jetbrains.kotlin.backend.common.lower.parents
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.symbols.IrTypeAliasSymbol
+import org.jetbrains.kotlin.ir.util.classIdOrFail
+
+internal fun getTypealiasSymbolIfActualizedViaTypealias(
+    expectDeclaration: IrDeclaration,
+    classActualizationInfo: ClassActualizationInfo,
+): IrTypeAliasSymbol? {
+    val topLevelExpectClass = getContainingTopLevelClass(expectDeclaration) ?: return null
+    val classId = topLevelExpectClass.classIdOrFail
+    return classActualizationInfo.actualTypeAliases[classId]
+}
+
+internal fun getContainingTopLevelClass(expectDeclaration: IrDeclaration): IrClass? {
+    val parentsWithSelf = sequenceOf(expectDeclaration) + expectDeclaration.parents
+    return parentsWithSelf.filterIsInstance<IrClass>().lastOrNull()
+}