[SLC] SymbolKotlinAsJavaSupport: implement getKotlinInternalClasses

^KTIJ-24067

analysis/analysis-api-providers/src/org/jetbrains/kotlin/analysis/providers/KotlinDeclarationProvider.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.
  */
 
@@ -35,6 +35,11 @@ public abstract class KotlinDeclarationProvider {
 
     public abstract fun findFilesForFacadeByPackage(packageFqName: FqName): Collection<KtFile>
     public abstract fun findFilesForFacade(facadeFqName: FqName): Collection<KtFile>
+
+    /**
+     * Currently we want only classes from libraries ([org.jetbrains.kotlin.analysis.decompiler.psi.file.KtClsFile])
+     */
+    public abstract fun findInternalFilesForFacade(facadeFqName: FqName): Collection<KtFile>
 }
 
 public abstract class KotlinDeclarationProviderFactory {

analysis/analysis-api-providers/src/org/jetbrains/kotlin/analysis/providers/impl/KotlinStaticDeclarationIndex.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.psi.*
 
 internal class KotlinStaticDeclarationIndex {
     internal val facadeFileMap: MutableMap<FqName, MutableSet<KtFile>> = mutableMapOf()
+    internal val multiFileClassPartMap: MutableMap<FqName, MutableSet<KtFile>> = mutableMapOf()
     internal val classMap: MutableMap<FqName, MutableSet<KtClassOrObject>> = mutableMapOf()
     internal val typeAliasMap: MutableMap<FqName, MutableSet<KtTypeAlias>> = mutableMapOf()
     internal val topLevelFunctionMap: MutableMap<FqName, MutableSet<KtNamedFunction>> = mutableMapOf()

analysis/analysis-api-providers/src/org/jetbrains/kotlin/analysis/providers/impl/KotlinStaticDeclarationProvider.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.
  */
 
@@ -8,7 +8,9 @@ package org.jetbrains.kotlin.analysis.providers.impl
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.openapi.vfs.impl.jar.CoreJarFileSystem
-import com.intellij.psi.*
+import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiManager
+import com.intellij.psi.SingleRootFileViewProvider
 import com.intellij.psi.search.GlobalSearchScope
 import com.intellij.psi.stubs.StubElement
 import com.intellij.util.indexing.FileContent
@@ -77,6 +79,10 @@ public class KotlinStaticDeclarationProvider internal constructor(
             .filter { it.javaFileFacadeFqName == facadeFqName }
     }
 
+    override fun findInternalFilesForFacade(facadeFqName: FqName): Collection<KtFile> {
+        return index.multiFileClassPartMap[facadeFqName].orEmpty().filter { it.virtualFile in scope }
+    }
+
     override fun getTopLevelProperties(callableId: CallableId): Collection<KtProperty> =
         index.topLevelPropertyMap[callableId.packageName]
             ?.filter { ktProperty ->
@@ -240,7 +246,18 @@ public class KotlinStaticDeclarationProviderFactory(
         }
 
         loadBuiltIns().forEach { ktFileStub ->
-            addToFacadeFileMap(ktFileStub.psi)
+            val ktFile: KtFile = ktFileStub.psi
+            addToFacadeFileMap(ktFile)
+
+            val partNames = ktFileStub.facadePartSimpleNames
+            if (partNames != null) {
+                val packageFqName = ktFileStub.getPackageFqName()
+                for (partName in partNames) {
+                    val multiFileClassPartFqName: FqName = packageFqName.child(Name.identifier(partName))
+                    index.multiFileClassPartMap.computeIfAbsent(multiFileClassPartFqName) { mutableSetOf() }.add(ktFile)
+                }
+            }
+
             // top-level functions and properties, built-in classes
             ktFileStub.childrenStubs.forEach(::indexStub)
         }