Reflection: support Java anonymous/local classes

Local classes and anonymous objects are normal classes and
kotlin-reflect can load all declarations and modifiers from them, and
support calling members, exactly in the same way as it does for normal
non-local classes.

 #KT-41373 In Progress

compiler/testData/codegen/box/reflection/localClasses/localClassesAndAnonymousObjects.kt

@@ -116,9 +116,8 @@ fun box(): String {
     checkKotlinAnonymousObject()
     checkKotlinLocalClass()
 
-    // TODO: fails with KotlinReflectionInternalError: Unresolved class: class JavaClass$1 (kind = null)
+    checkJavaAnonymousObject()
-    // checkJavaAnonymousObject()
+    checkJavaLocalClass()
-    // checkJavaLocalClass()
 
     return "OK"
 }

core/descriptors.runtime/src/org/jetbrains/kotlin/descriptors/runtime/structure/ReflectJavaClass.kt

@@ -105,7 +105,14 @@ class ReflectJavaClass(
         get() = null
 
     override val name: Name
-        get() = Name.identifier(klass.simpleName)
+        get() = if (klass.isAnonymousClass) {
+            // For anonymous classes, `Class.simpleName` returns an empty string in Java reflection.
+            // We don't want that because it breaks all sorts of invariants on names which cannot be empty in Kotlin.
+            // So we extract the simple name from the full JVM binary name, e.g. "org.test.Foo$1" -> "Foo$1".
+            Name.identifier(klass.name.substringAfterLast("."))
+        } else {
+            Name.identifier(klass.simpleName)
+        }
 
     override val typeParameters: List<ReflectJavaTypeParameter>
         get() = klass.typeParameters.map(::ReflectJavaTypeParameter)

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KClassImpl.kt

@@ -51,8 +51,13 @@ internal class KClassImpl<T : Any>(
             val moduleData = data.value.moduleData
 
             val descriptor =
-                if (classId.isLocal) moduleData.deserialization.deserializeClass(classId)
+                if (classId.isLocal && jClass.isAnnotationPresent(Metadata::class.java)) {
-                else moduleData.module.findClassAcrossModuleDependencies(classId)
+                    // If it's a Kotlin local class or anonymous object, deserialize its metadata directly because it cannot be found via
+                    // `module.findClassAcrossModuleDependencies`.
+                    moduleData.deserialization.deserializeClass(classId)
+                } else {
+                    moduleData.module.findClassAcrossModuleDependencies(classId)
+                }
 
             descriptor ?: reportUnresolvedClass()
         }