Issue 23389. Report error in the renamed element be invisible after rename.

pkg/analysis_server/lib/src/services/refactoring/rename_unit_member.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library services.src.refactoring.rename_unit_member;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart'
     show newLocation_fromElement, newLocation_fromMatch;
 import 'package:analysis_server/src/services/correction/status.dart';
 import 'package:analysis_server/src/services/correction/util.dart';
 import 'package:analysis_server/src/services/refactoring/naming_conventions.dart';
 import 'package:analysis_server/src/services/refactoring/refactoring.dart';
 import 'package:analysis_server/src/services/refactoring/rename.dart';
 import 'package:analysis_server/src/services/search/element_visitors.dart';
 import 'package:analysis_server/src/services/search/search_engine.dart';
+import 'package:analyzer/src/generated/ast.dart' show Identifier;
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/java_core.dart';
 
 /**
  * Checks if creating a top-level function with the given [name] in [library]
  * will cause any conflicts.
  */
 Future<RefactoringStatus> validateCreateFunction(
     SearchEngine searchEngine, LibraryElement library, String name) {
   return new _RenameUnitMemberValidator.forCreate(
@@ skipping 92 matching lines @@
 
   final RefactoringStatus result = new RefactoringStatus();
 
   _RenameUnitMemberValidator.forCreate(
       this.searchEngine, this.library, this.elementKind, this.name)
       : isRename = false;
 
   _RenameUnitMemberValidator.forRename(
       this.searchEngine, this.element, this.name)
       : isRename = true {
-    library = element.getAncestor((e) => e is LibraryElement);
+    library = element.library;
     elementKind = element.kind;
   }
 
   Future<RefactoringStatus> validate() async {
     _validateWillConflict();
     if (isRename) {
+      await _validateWillBeInvisible();
       await _validateWillBeShadowed();
     }
     await _validateWillShadow();
     return result;
   }
 
   /**
    * Returns `true` if [element] is visible at the given [SearchMatch].
    */
   bool _isVisibleAt(Element element, SearchMatch at) {
@@ skipping 11 matching lines @@
       // check imported elements
       if (getImportNamespace(importElement).containsValue(element)) {
         return true;
       }
     }
     // no, it is not visible
     return false;
   }
 
   /**
+   * Validates if any usage of [element] renamed to [name] will be invisible.
+   */
+  Future _validateWillBeInvisible() async {

[Brian Wilkerson, 2015/06/01 17:32:29]

It's sad to see this method duplicated. Could we move it to a base class that
both extend?

+    if (!Identifier.isPrivateName(name)) {
+      return;
+    }
+    List<SearchMatch> references = await searchEngine.searchReferences(element);
+    for (SearchMatch reference in references) {
+      Element refElement = reference.element;
+      LibraryElement refLibrary = refElement.library;
+      if (refLibrary != library) {
+        String message = format("Renamed {0} will be invisible in '{1}'.",
+            getElementKindName(element), getElementQualifiedName(refLibrary));
+        result.addError(message, newLocation_fromMatch(reference));
+      }
+    }
+  }
+
+  /**
    * Validates if any usage of [element] renamed to [name] will be shadowed.
    */
   Future _validateWillBeShadowed() async {
-    if (!isRename) {
-      return;
-    }
     List<SearchMatch> references = await searchEngine.searchReferences(element);
     for (SearchMatch reference in references) {
       Element refElement = reference.element;
       ClassElement refClass = refElement.getAncestor((e) => e is ClassElement);
       if (refClass != null) {
         visitChildren(refClass, (shadow) {
           if (hasDisplayName(shadow, name)) {
             String message = format(
                 "Reference to renamed {0} will be shadowed by {1} '{2}'.",
                 getElementKindName(element), getElementKindName(shadow),
@@ skipping 49 matching lines @@
         // OK, reference will be shadowed be the element being renamed
         String message = format(isRename
                 ? "Renamed {0} will shadow {1} '{2}'."
                 : "Created {0} will shadow {1} '{2}'.", elementKind.displayName,
             getElementKindName(member), getElementQualifiedName(member));
         result.addError(message, newLocation_fromMatch(memberReference));
       }
     }
   }
 }