Report 'nested class accessed via instance reference' error

idea/testData/diagnosticMessage/nestedClassAcessedViaInstanceReference.kt

@@ -0,0 +1,16 @@
+// !DIAGNOSTICS_NUMBER: 4
+// !DIAGNOSTICS: NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE
+
+class A {
+    class Nested()
+    class NestedWithClassObject { class object }
+    enum class NestedEnum { A }
+    object NestedObj { fun invoke() = 1 }
+}
+
+fun test(a: A) {
+    a.Nested()
+    a.NestedWithClassObject
+    a.NestedEnum
+    a.NestedObj
+}