Report errors and warnings for hiding elements, issue 572.

compiler/lib/implementation/string.dart

 // Copyright (c) 2011, 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.
 
 class StringImplementation implements String native "String" {
   factory StringImplementation.fromValues(List<int> values) {
     return _newFromValues(values);
   }
 
   String operator[](int index) {
@@ skipping 196 matching lines @@
 class _StringMatch implements Match {
   const _StringMatch(int this._start,
                      String this.str,
                      String this.pattern);
 
   int start() => _start;
   int end() => _start + pattern.length;
   String operator[](int g) => group(g);
   int groupCount() => 0;
 
-  String group(int group) {
-    if (group != 0) {
-      throw new IndexOutOfRangeException(group);
+  String group(int group_) {
+    if (group_ != 0) {
+      throw new IndexOutOfRangeException(group_);
     }
     return pattern;
   }
 
-  List<String> groups(List<int> groups) {
+  List<String> groups(List<int> groups_) {
     List<String> result = new List<String>();
-    for (int g in groups) {
+    for (int g in groups_) {
       result.add(group(g));
     }
     return result;
   }
 
   final int _start;
   final String str;
   final String pattern;
 }