Nested classes are no more allowed inside any anonymous objects or local classes #KT-13510 Fixed

(cherry picked from commit 5c3ec6c)

compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.java

@@ -94,7 +94,7 @@ public class ModifiersChecker {
         DeclarationDescriptor containingDeclaration = descriptor.getContainingDeclaration();
         if (!(containingDeclaration instanceof ClassDescriptor)) return false;
         ClassDescriptor containingClass = (ClassDescriptor) containingDeclaration;
-        return containingClass.isInner() || containingClass.getContainingDeclaration() instanceof FunctionDescriptor;
+        return containingClass.isInner() || DescriptorUtils.isLocal(containingClass);
     }
 
     @NotNull

compiler/testData/diagnostics/tests/inner/kt6026.kt

@@ -1,7 +1,8 @@
 // KT-6026 Exception on instantiating a nested class in an anonymous object
 
 val oo = object {
-    class Nested
+    // Forbidden in KT-13510
+    <!NESTED_CLASS_NOT_ALLOWED!>class Nested<!>
 
     fun f1() = Nested(<!TOO_MANY_ARGUMENTS!>11<!>)
 }

compiler/testData/diagnostics/tests/objects/nestedClassInAnonymousObject.kt

@@ -0,0 +1,11 @@
+class X {
+    val foo = object {
+        <!NESTED_CLASS_NOT_ALLOWED!>class Foo<!>
+    }
+
+    fun test() {
+        object {
+            <!NESTED_CLASS_NOT_ALLOWED!>class Foo<!>
+        }
+    }
+}

compiler/testData/diagnostics/tests/objects/nestedClassInAnonymousObject.txt

@@ -0,0 +1,10 @@
+package
+
+public final class X {
+    public constructor X()
+    public final val foo: kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final fun test(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -12510,6 +12510,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("nestedClassInAnonymousObject.kt")
+            public void testNestedClassInAnonymousObject() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/objects/nestedClassInAnonymousObject.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("objectInsideFun.kt")
             public void testObjectInsideFun() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/objects/objectInsideFun.kt");