Report 'nested class accessed via instance reference' error

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

@@ -23,6 +23,6 @@ class Outer {
 
 fun Outer.foo() {
     Outer()
-    <!UNRESOLVED_REFERENCE!>Nested<!>()
+    <!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>Nested<!>()
     Inner()
 }

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

@@ -0,0 +1,54 @@
+trait N { fun foo() = 1 }
+
+class WithClassObject {
+    class object {}
+
+    class Nested()
+    class NestedWithClassObject { class object : N }
+    enum class NestedEnum { A }
+    object NestedObj : N { fun invoke() = 1 }
+}
+
+class WithoutClassObject {
+    class Nested()
+    class NestedWithClassObject { class object : N }
+    enum class NestedEnum { A }
+    object NestedObj : N { fun invoke() = 1 }
+}
+
+object Obj {
+    class Nested()
+    class NestedWithClassObject { class object : N }
+    enum class NestedEnum { A }
+    object NestedObj : N { fun invoke() = 1 }
+}
+
+fun test(with: WithClassObject, without: WithoutClassObject, obj: Obj) {
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>Nested<!>()
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>()
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>.foo()
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedEnum<!>.A
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>()
+    with.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>.foo()
+
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>Nested<!>()
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>()
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>.foo()
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedEnum<!>.A
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>()
+    without.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>.foo()
+
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>Nested<!>()
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>()
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedWithClassObject<!>.foo()
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedEnum<!>.A
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>()
+    obj.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>NestedObj<!>.foo()
+}
+

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

@@ -0,0 +1,12 @@
+//no nested class access via instance reference error
+fun test() {
+    A.f(<!TYPE_MISMATCH!>""<!>)
+}
+
+class A() {
+    class object {
+        object f {
+            fun invoke(i: Int) = i
+        }
+    }
+}

compiler/testData/diagnostics/testsWithStdLib/callableReference/function/nestedConstructorFromExtension.kt

@@ -6,7 +6,7 @@ class A {
 }
     
 fun A.main() {
-    ::<!UNRESOLVED_REFERENCE!>Nested<!>
+    ::<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>Nested<!>
     val y = A::Nested
     
     y : KFunction0<A.Nested>