[LL] ensure that stub based symbol provider works on class files

This makes `.originalElements` calls redundant, no need to filter duplicates.
Additionally, it ensures that ktDeclaration's are from cls,
so all types are fully qualified and stubs contain all additional information,
required to build resolved fir e.g.,
fully qualified names are split as classIds, flexible types, etc

Merge-request: KT-MR-10449
Merged-by: Anna Kozlova <Anna.Kozlova@jetbrains.com>

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/stubBased/deserialization/JvmStubBasedDeserializedSymbolProviderFactory.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.analysis.low.level.api.fir.stubBased.deserialization
 
+import com.intellij.ide.highlighter.JavaClassFileType
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.psi.search.DelegatingGlobalSearchScope
@@ -20,7 +21,6 @@ import org.jetbrains.kotlin.fir.java.FirJavaFacade
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
 import org.jetbrains.kotlin.fir.scopes.FirKotlinScopeProvider
 import org.jetbrains.kotlin.load.kotlin.PackagePartProvider
-import org.jetbrains.kotlin.serialization.deserialization.builtins.BuiltInSerializerProtocol
 
 @LLFirInternals
 class JvmStubBasedDeserializedSymbolProviderFactory : JvmFirDeserializedSymbolProviderFactory() {
@@ -47,7 +47,7 @@ class JvmStubBasedDeserializedSymbolProviderFactory : JvmFirDeserializedSymbolPr
                     project,
                     object : DelegatingGlobalSearchScope(project, scope) {
                         override fun contains(file: VirtualFile): Boolean {
-                            if (file.extension == BuiltInSerializerProtocol.BUILTINS_FILE_EXTENSION) {
+                            if (file.extension != JavaClassFileType.INSTANCE.defaultExtension) {
                                 return false
                             }
                             return super.contains(file)

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/stubBased/deserialization/JvmStubBasedFirDeserializedSymbolProvider.kt

@@ -81,7 +81,7 @@ internal open class JvmStubBasedFirDeserializedSymbolProvider(
         context: StubBasedFirDeserializationContext?,
     ): Pair<FirTypeAliasSymbol?, DeserializedTypeAliasPostProcessor?> {
         val classLikeDeclaration =
-            (context?.classLikeDeclaration ?: declarationProvider.getClassLikeDeclarationByClassId(classId))?.originalElement
+            (context?.classLikeDeclaration ?: declarationProvider.getClassLikeDeclarationByClassId(classId))
         if (classLikeDeclaration is KtTypeAlias) {
             val symbol = FirTypeAliasSymbol(classId)
             val postProcessor: DeserializedTypeAliasPostProcessor = {
@@ -106,9 +106,9 @@ internal open class JvmStubBasedFirDeserializedSymbolProvider(
     ): FirRegularClassSymbol? {
         val (classLikeDeclaration, context) =
             if (parentContext?.classLikeDeclaration != null) {
-                parentContext.classLikeDeclaration.originalElement to null
+                parentContext.classLikeDeclaration to null
             } else {
-                (declarationProvider.getClassLikeDeclarationByClassId(classId)?.originalElement ?: return null) to parentContext
+                (declarationProvider.getClassLikeDeclarationByClassId(classId) ?: return null) to parentContext
             }
 
         val symbol = FirRegularClassSymbol(classId)
@@ -140,12 +140,9 @@ internal open class JvmStubBasedFirDeserializedSymbolProvider(
         foundFunctions: Collection<KtNamedFunction>?,
     ): List<FirNamedFunctionSymbol> {
         val topLevelFunctions = foundFunctions ?: declarationProvider.getTopLevelFunctions(callableId)
-        val origins = if (topLevelFunctions.size > 1) mutableSetOf<KtNamedFunction>() else null
         return topLevelFunctions
             .mapNotNull { function ->
-                val original = function.originalElement as? KtNamedFunction ?: return@mapNotNull null
+                val file = function.containingKtFile
-                if (origins != null && !origins.add(original)) return@mapNotNull null
-                val file = original.containingKtFile
                 val virtualFile = file.virtualFile
                 if (virtualFile.extension == MetadataPackageFragment.METADATA_FILE_EXTENSION) return@mapNotNull null
                 if (initialOrigin != FirDeclarationOrigin.BuiltIns && file.packageFqName.asString()
@@ -153,22 +150,19 @@ internal open class JvmStubBasedFirDeserializedSymbolProvider(
                 ) return@mapNotNull null
                 val symbol = FirNamedFunctionSymbol(callableId)
                 val rootContext =
-                    StubBasedFirDeserializationContext.createRootContext(session, moduleData, callableId, original, symbol, initialOrigin)
+                    StubBasedFirDeserializationContext.createRootContext(session, moduleData, callableId, function, symbol, initialOrigin)
-                rootContext.memberDeserializer.loadFunction(original, null, session, symbol).symbol
+                rootContext.memberDeserializer.loadFunction(function, null, session, symbol).symbol
             }
     }
 
     private fun loadPropertiesByCallableId(callableId: CallableId, foundProperties: Collection<KtProperty>?): List<FirPropertySymbol> {
         val topLevelProperties = foundProperties ?: declarationProvider.getTopLevelProperties(callableId)
-        val origins = if (topLevelProperties.size > 1) mutableSetOf<KtProperty>() else null
         return topLevelProperties
-            .mapNotNull { property ->
+            .map { property ->
-                val original = property.originalElement as? KtProperty ?: return@mapNotNull null
-                if (origins != null && !origins.add(original)) return@mapNotNull null
                 val symbol = FirPropertySymbol(callableId)
                 val rootContext =
-                    StubBasedFirDeserializationContext.createRootContext(session, moduleData, callableId, original, symbol, initialOrigin)
+                    StubBasedFirDeserializationContext.createRootContext(session, moduleData, callableId, property, symbol, initialOrigin)
-                rootContext.memberDeserializer.loadProperty(original, null, symbol).symbol
+                rootContext.memberDeserializer.loadProperty(property, null, symbol).symbol
             }
     }