Added error 'NESTED_CLASS_SHOULD_BE_QUALIFIED'

when nested class is resolved through implicit this

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java

@@ -602,6 +602,7 @@ public interface Errors {
     DiagnosticFactory1<JetSimpleNameExpression, TypeParameterDescriptor> TYPE_PARAMETER_IS_NOT_AN_EXPRESSION = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<JetSimpleNameExpression, TypeParameterDescriptor> TYPE_PARAMETER_ON_LHS_OF_DOT = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<JetExpression, ClassDescriptor> NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory1<JetExpression, ClassDescriptor> NESTED_CLASS_SHOULD_BE_QUALIFIED = DiagnosticFactory1.create(ERROR);
 
     DiagnosticFactory1<PsiElement, ClassDescriptor> INACCESSIBLE_OUTER_CLASS_EXPRESSION = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory0<JetClass> NESTED_CLASS_NOT_ALLOWED = DiagnosticFactory0.create(ERROR, DECLARATION_NAME);

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/rendering/DefaultErrorMessages.java

@@ -262,6 +262,7 @@ public class DefaultErrorMessages {
         MAP.put(TYPE_PARAMETER_ON_LHS_OF_DOT, "Type parameter ''{0}'' cannot have or inherit a class object, so it cannot be on the left hand side of dot", NAME);
         MAP.put(NO_GENERICS_IN_SUPERTYPE_SPECIFIER, "Generic arguments of the base type must be specified");
         MAP.put(NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE, "Nested {0} accessed via instance reference", RENDER_CLASS_OR_OBJECT_NAME);
+        MAP.put(NESTED_CLASS_SHOULD_BE_QUALIFIED, "Nested {0} should be qualified", RENDER_CLASS_OR_OBJECT_NAME);
 
         MAP.put(INACCESSIBLE_OUTER_CLASS_EXPRESSION, "Expression is inaccessible from a nested class ''{0}'', use ''inner'' keyword to make the class inner", NAME);
         MAP.put(NESTED_CLASS_NOT_ALLOWED, "Nested class is not allowed here, use ''inner'' keyword to make the class inner");

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/CandidateResolver.java

@@ -188,7 +188,7 @@ public class CandidateResolver {
                 nestedClass = ((FakeCallableDescriptorForObject) candidateDescriptor).getReferencedDescriptor();
             }
             if (nestedClass != null) {
-                context.tracing.nestedClassAccessViaInstanceReference(context.trace, nestedClass);
+                context.tracing.nestedClassAccessViaInstanceReference(context.trace, nestedClass, candidateCall.getExplicitReceiverKind());
                 return false;
             }
         }

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/tasks/AbstractTracingStrategy.java

@@ -128,8 +128,17 @@ public abstract class AbstractTracingStrategy implements TracingStrategy {
     }
 
     @Override
-    public void nestedClassAccessViaInstanceReference(@NotNull BindingTrace trace, @NotNull ClassDescriptor classDescriptor) {
-        trace.report(NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE.on(reference, classDescriptor));
+    public void nestedClassAccessViaInstanceReference(
+            @NotNull BindingTrace trace,
+            @NotNull ClassDescriptor classDescriptor,
+            @NotNull ExplicitReceiverKind explicitReceiverKind
+    ) {
+        if (explicitReceiverKind == ExplicitReceiverKind.NO_EXPLICIT_RECEIVER) {
+            trace.report(NESTED_CLASS_SHOULD_BE_QUALIFIED.on(reference, classDescriptor));
+        }
+        else {
+            trace.report(NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE.on(reference, classDescriptor));
+        }
     }
 
     @Override

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/tasks/TracingStrategy.java

@@ -81,7 +81,11 @@ public interface TracingStrategy {
         public void instantiationOfAbstractClass(@NotNull BindingTrace trace) {}
 
         @Override
-        public void nestedClassAccessViaInstanceReference(@NotNull BindingTrace trace, @NotNull ClassDescriptor classDescriptor) {}
+        public void nestedClassAccessViaInstanceReference(
+                @NotNull BindingTrace trace,
+                @NotNull ClassDescriptor classDescriptor,
+                @NotNull ExplicitReceiverKind explicitReceiverKind
+        ) {}
 
         @Override
         public void unsafeCall(@NotNull BindingTrace trace, @NotNull JetType type, boolean isCallForImplicitInvoke) {}
@@ -132,7 +136,11 @@ public interface TracingStrategy {
 
     void instantiationOfAbstractClass(@NotNull BindingTrace trace);
 
-    void nestedClassAccessViaInstanceReference(@NotNull BindingTrace trace, @NotNull ClassDescriptor classDescriptor);
+    void nestedClassAccessViaInstanceReference(
+            @NotNull BindingTrace trace,
+            @NotNull ClassDescriptor classDescriptor,
+            @NotNull ExplicitReceiverKind explicitReceiverKind
+    );
 
     void unsafeCall(@NotNull BindingTrace trace, @NotNull JetType type, boolean isCallForImplicitInvoke);
 

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ControlStructureTypingUtils.java

@@ -35,6 +35,7 @@ import org.jetbrains.jet.lang.resolve.calls.inference.*;
 import org.jetbrains.jet.lang.resolve.calls.model.MutableDataFlowInfoForArguments;
 import org.jetbrains.jet.lang.resolve.calls.model.ResolvedCall;
 import org.jetbrains.jet.lang.resolve.calls.results.OverloadResolutionResults;
+import org.jetbrains.jet.lang.resolve.calls.tasks.ExplicitReceiverKind;
 import org.jetbrains.jet.lang.resolve.calls.tasks.ResolutionCandidate;
 import org.jetbrains.jet.lang.resolve.calls.tasks.TracingStrategy;
 import org.jetbrains.jet.lang.resolve.calls.util.CallMaker;
@@ -456,7 +457,8 @@ public class ControlStructureTypingUtils {
 
         @Override
         public void nestedClassAccessViaInstanceReference(
-                @NotNull BindingTrace trace, @NotNull ClassDescriptor classDescriptor
+                @NotNull BindingTrace trace, @NotNull ClassDescriptor classDescriptor,
+                @NotNull ExplicitReceiverKind explicitReceiverKind
         ) {
             throwError();
         }

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

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

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

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