Report "cannot infer visibility" for delegated members

compiler/frontend/src/org/jetbrains/jet/lang/resolve/DelegationResolver.java

@@ -32,6 +32,7 @@ import org.jetbrains.jet.lang.types.TypeUtils;
 
 import java.util.*;
 
+import static org.jetbrains.jet.lang.descriptors.CallableMemberDescriptor.Kind.DELEGATION;
 import static org.jetbrains.jet.lang.diagnostics.Errors.MANY_IMPL_MEMBER_NOT_IMPLEMENTED;
 import static org.jetbrains.jet.lang.resolve.OverridingUtil.OverrideCompatibilityInfo.Result.OVERRIDABLE;
 
@@ -161,8 +162,7 @@ public final class DelegationResolver<T extends CallableMemberDescriptor> {
         for (T memberDescriptor : descriptorsToDelegate) {
             Modality newModality = memberDescriptor.getModality() == Modality.ABSTRACT ? Modality.OPEN : memberDescriptor.getModality();
             @SuppressWarnings("unchecked")
-            T copy = (T) memberDescriptor.copy(ownerDescriptor, newModality, memberDescriptor.getVisibility(),
-                                               CallableMemberDescriptor.Kind.DELEGATION, false);
+            T copy = (T) memberDescriptor.copy(ownerDescriptor, newModality, Visibilities.INHERITED, DELEGATION, false);
             result.add(copy);
         }
         return result;

compiler/frontend/src/org/jetbrains/jet/lang/resolve/OverrideResolver.java

@@ -178,7 +178,7 @@ public class OverrideResolver {
         return new Function1<CallableMemberDescriptor, Unit>() {
             @Override
             public Unit invoke(@NotNull CallableMemberDescriptor descriptor) {
-                DeclarationDescriptor reportOn = descriptor.getKind() == FAKE_OVERRIDE
+                DeclarationDescriptor reportOn = descriptor.getKind() == FAKE_OVERRIDE || descriptor.getKind() == DELEGATION
                                                  ? DescriptorUtils.getParentOfType(descriptor, ClassDescriptor.class)
                                                  : descriptor;
                 //noinspection ConstantConditions

compiler/testData/diagnostics/tests/override/kt4785delegation.kt

@@ -0,0 +1,9 @@
+trait A {
+    internal fun foo()
+}
+
+trait B {
+    protected fun foo()
+}
+
+class <!CANNOT_INFER_VISIBILITY!>E(a: A)<!> : A by a, B

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -5394,6 +5394,11 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest("compiler/testData/diagnostics/tests/override/kt4785classObject.kt");
             }
             
+            @TestMetadata("kt4785delegation.kt")
+            public void testKt4785delegation() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/override/kt4785delegation.kt");
+            }
+            
             @TestMetadata("kt880.kt")
             public void testKt880() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/override/kt880.kt");