Fix field-accesses for private fields that were "shadowed" by other private fields.

lib/compiler/implementation/world.dart

 // Copyright (c) 2012, 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 World {
   Compiler compiler;  // Set in populate().
   final Map<ClassElement, Set<ClassElement>> subtypes;
 
   World() : subtypes = new Map<ClassElement, Set<ClassElement>>();
 
@@ skipping 11 matching lines @@
     }
 
     compiler.resolverWorld.instantiatedClasses.forEach(addSubtypes);
 
     // Mark the world as populated.
     assert(compiler !== null);
     this.compiler = compiler;
   }
 
   /**
-   * Returns a [MemberSet] that contains the possible targets of a
-   * selector named [member] on a receiver whose type is [type].
+   * Returns a [MemberSet] that contains the possible targets of the given
+   * [selector] on a receiver with the given [type].
    */
-  MemberSet _memberSetFor(Type type, SourceString member) {
+  MemberSet _memberSetFor(Type type, Selector selector) {
     assert(compiler !== null);
     ClassElement cls = type.element;
-    MemberSet result = new MemberSet(member);
-    Element element = cls.lookupMember(member);
+    SourceString name = selector.name;
+    LibraryElement library = selector.library;
+    MemberSet result = new MemberSet(name);
+    Element element = cls.lookupSelector(selector);
     if (element !== null) result.add(element);
 
+    bool isPrivate = name.isPrivate();
     Set<ClassElement> subtypesOfCls = subtypes[cls];
     if (subtypesOfCls !== null) {
       for (ClassElement sub in subtypesOfCls) {
-        element = sub.lookupLocalMember(member);
+        // Private members from a different library are not visible.
+        if (isPrivate && sub.getLibrary() != library) continue;
+        element = sub.lookupLocalMember(name);
         if (element !== null) result.add(element);
       }
     }
     return result;
   }
 
   /**
-   * Returns the single field with the given name, if such a field
-   * exists. If there are multple fields, or none, return null.
+   * Returns the single field with the given [selector]. If there is no such
+   * field, or there are multiple possible fields returns [:null:].
    */
-  VariableElement locateSingleField(Type type, SourceString member) {
-    MemberSet memberSet = _memberSetFor(type, member);
+  VariableElement locateSingleField(Type type, Selector selector) {
+    MemberSet memberSet = _memberSetFor(type, selector);
     int fieldCount = 0;
     int nonFieldCount = 0;
     VariableElement field;
     memberSet.elements.forEach((Element element) {
       if (element.isField()) {
         field = element;
         fieldCount++;
       } else {
         nonFieldCount++;
       }
     });
     return (fieldCount == 1 && nonFieldCount == 0) ? field : null;
   }
 
   Set<ClassElement> findNoSuchMethodHolders(Type type) {
     Set<ClassElement> result = new Set<ClassElement>();
-    MemberSet memberSet = _memberSetFor(type, Compiler.NO_SUCH_METHOD);
     Selector noSuchMethodSelector = new Selector.noSuchMethod();
+    MemberSet memberSet = _memberSetFor(type, noSuchMethodSelector);
     for (Element element in memberSet.elements) {
       ClassElement holder = element.getEnclosingClass();
       if (holder !== compiler.objectClass &&
           noSuchMethodSelector.applies(element, compiler)) {
         result.add(holder);
       }
     }
     return result;
   }
 }
 
 /**
  * A [MemberSet] contains all the possible targets for a selector.
  */
 class MemberSet {
   final Set<Element> elements;
   final SourceString name;
 
   MemberSet(SourceString this.name) : elements = new Set<Element>();
 
   void add(Element element) {
     elements.add(element);
   }
 
   bool isEmpty() => elements.isEmpty();
 }