FIR IDE: use KtClassLikeDeclaration.classId instead of hacks

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/providers/FirProviderHelper.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.idea.fir.low.level.api.util.executeOrReturnDefaultVa
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.psi.KtClassOrObject
 import org.jetbrains.kotlin.psi.KtEnumEntry
 import org.jetbrains.kotlin.psi.KtFile
 import java.util.*
@@ -35,10 +36,10 @@ internal class FirProviderHelper(
     fun getFirClassifierByFqName(classId: ClassId): FirClassLikeDeclaration<*>? {
         return executeOrReturnDefaultValueOnPCE(null) {
             cache.classifierByClassId.computeIfAbsent(classId) {
-                val ktClass = indexHelper.classFromIndexByClassId(classId)
-                    ?: indexHelper.typeAliasFromIndexByClassId(classId)
-                    ?: return@computeIfAbsent Optional.empty()
-                if (ktClass is KtEnumEntry) return@computeIfAbsent Optional.empty()
+                val ktClass = when (val klass = indexHelper.classFromIndexByClassId(classId)) {
+                    null -> indexHelper.typeAliasFromIndexByClassId(classId)
+                    else -> if (klass.getClassId() == null) null else klass
+                } ?: return@computeIfAbsent Optional.empty()
                 val firFile = firFileBuilder.buildRawFirFileWithCaching(ktClass.containingKtFile, cache, lazyBodiesMode = true)
                 val classifier = FirElementFinder.findElementIn<FirClassLikeDeclaration<*>>(firFile) { classifier ->
                     classifier.symbol.classId == classId

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/util/declarationUtils.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.resolve.firProvider
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
 import org.jetbrains.kotlin.fir.resolve.toFirRegularClass
+import org.jetbrains.kotlin.fir.symbols.impl.FirClassLikeSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.idea.fir.low.level.api.api.InvalidFirElementTypeException
 import org.jetbrains.kotlin.idea.fir.low.level.api.api.collectDesignation
@@ -17,7 +18,6 @@ import org.jetbrains.kotlin.idea.fir.low.level.api.element.builder.getNonLocalCo
 import org.jetbrains.kotlin.idea.fir.low.level.api.file.builder.FirFileBuilder
 import org.jetbrains.kotlin.idea.fir.low.level.api.file.builder.ModuleFileCache
 import org.jetbrains.kotlin.idea.fir.low.level.api.providers.firIdeProvider
-import org.jetbrains.kotlin.idea.util.classIdIfNonLocal
 import org.jetbrains.kotlin.idea.util.getElementTextInContext
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.psi.*
@@ -84,7 +84,7 @@ private fun KtDeclaration.findSourceNonLocalFirDeclarationByProvider(
         this is KtNamedDeclaration && (this is KtProperty || this is KtNamedFunction) -> {
             val containerClass = containingClassOrObject
             val declarations = if (containerClass != null) {
-                val containerClassFir = containerClass.findFir(firSymbolProvider)
+                val containerClassFir = containerClass.findFir(firSymbolProvider) as? FirRegularClass
                 containerClassFir?.declarations
             } else {
                 val ktFile = containingKtFile
@@ -102,7 +102,7 @@ private fun KtDeclaration.findSourceNonLocalFirDeclarationByProvider(
         this is KtConstructor<*> -> {
             val containingClass = containingClassOrObject
                 ?: error("Container class should be not null for KtConstructor")
-            val containerClassFir = containingClass.findFir(firSymbolProvider) ?: return null
+            val containerClassFir = containingClass.findFir(firSymbolProvider) as? FirRegularClass ?: return null
             containerClassFir.declarations.firstOrNull { it.psi === this }
         }
         this is KtTypeAlias -> findFir(firSymbolProvider)
@@ -118,20 +118,13 @@ private val ORIGINAL_KT_FILE_KEY = com.intellij.openapi.util.Key<KtFile>("ORIGIN
 var KtFile.originalKtFile by UserDataProperty(ORIGINAL_KT_FILE_KEY)
 
 
-private fun KtClassOrObject.findFir(firSymbolProvider: FirSymbolProvider): FirRegularClass? {
-    val classId = classIdIfNonLocal() ?: return null
+private fun KtClassLikeDeclaration.findFir(firSymbolProvider: FirSymbolProvider): FirClassLikeDeclaration<*>? {
+    val classId = getClassId() ?: return null
     return executeWithoutPCE {
         firSymbolProvider.getClassLikeSymbolByFqName(classId)?.fir as? FirRegularClass
     }
 }
 
-private fun KtTypeAlias.findFir(firSymbolProvider: FirSymbolProvider): FirTypeAlias? {
-    val typeAlias = ClassId(containingKtFile.packageFqName, nameAsSafeName)
-    return executeWithoutPCE {
-        // Finding a non-top-level type alias won't work
-        firSymbolProvider.getClassLikeSymbolByFqName(typeAlias)?.fir as? FirTypeAlias
-    }
-}
 
 val FirDeclaration.isGeneratedDeclaration
     get() = realPsi == null

idea/idea-frontend-independent/src/org/jetbrains/kotlin/idea/util/psiUtils.kt

@@ -40,17 +40,9 @@ fun KtElement.getElementTextInContext(): String {
 
 private const val ELEMENT_TAG = "ELEMENT"
 
-fun KtClassOrObject.classIdIfNonLocal(): ClassId? {
-    if (KtPsiUtil.isLocal(this)) return null
-    val packageName = containingKtFile.packageFqName
-    val classesNames = parentsOfType<KtDeclaration>().map { it.name }.toList().asReversed()
-    if (classesNames.any { it == null }) return null
-    return ClassId(packageName, FqName(classesNames.joinToString(separator = ".")), /*local=*/false)
-}
-
 fun PsiClass.classIdIfNonLocal(): ClassId? {
     if (this is KtLightClass) {
-        return this.kotlinOrigin?.classIdIfNonLocal()
+        return this.kotlinOrigin?.getClassId()
     }
     val packageName = (containingFile as? PsiJavaFile)?.packageName ?: return null
     val packageFqName = FqName(packageName)