Make addGetterOrSetter (now: defineAccessor) not add the abstract field as a member.

lib/compiler/implementation/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
   Type getType(TypeAnnotation annotation);
 }
 
@@ skipping 236 matching lines @@
 
   checkMembers(ClassElement cls) {
     if (cls === compiler.objectClass) return;
     cls.forEachMember((holder, member) {
       checkAbstractField(member);
       checkValidOverride(member, cls.lookupSuperMember(member.name));
     });
   }
 
   void checkAbstractField(Element member) {
-    if (member is !AbstractFieldElement) return;
-    if (member.getter === null) return;
-    if (member.setter === null) return;
-    int getterFlags = member.getter.modifiers.flags | Modifiers.FLAG_ABSTRACT;
-    int setterFlags = member.setter.modifiers.flags | Modifiers.FLAG_ABSTRACT;
+    // Only check for getters. The test can only fail if there is both a setter
+    // and a getter with the same name, and we only need to check each abstract
+    // field once, so we just ignore setters.
+    if (!member.isGetter()) return;
+
+    // Find the associated abstract field.
+    AbstractFieldElement field;
+    ClassElement outerClass = member.getEnclosingClass();
+    if (outerClass != null) {
+      Element element = outerClass.lookupLocalMember(member.name);
+      // This is wrong, but can currently happen. See, e.g., the test
+      // language/field2_negative_test where we are OK on failing.
+      if (element.kind !== ElementKind.ABSTRACT_FIELD) return;

[Anders Johnsen, 2012/08/07 13:02:30]

Returning here looks wrong, turn comment into TODO?

[ahe, 2012/08/10 11:21:46]

Please report the error. You have fixed a bug in dart2js. 

[Lasse Reichstein Nielsen, 2012/08/13 13:37:51]

Perhaps. It seems we continue compiling even if we detect duplicate names. This
is one of those cases. I.e., the model is borked and the abstract field has been
overwritten.
We should probably continue and report more errors.

[ahe, 2012/08/13 16:20:27]

Could please provide an example that illustrates when this code is in effect?

[Lasse Reichstein Nielsen, 2012/08/14 11:41:07]

Should happen for, e.g.:

   class A {
     external get x();
     int x() => 42;
   }

We were missing an error report for the duplicate declaration, and the latter
just overwrote the former in the scope. This can no longer happen after r10626,
so this should now be an internal error. I've changed it to be that.

+      field = element;
+    } else {
+      LibraryElement library = member.getLibrary();
+      field = library.findLocal(member.name);
+    }

[Anders Johnsen, 2012/08/07 13:02:30]

assert field !== null?

[ahe, 2012/08/10 11:21:46]

Better to use internalErrorOnElement.

[Lasse Reichstein Nielsen, 2012/08/13 13:37:51]

Done.

+
+    if (field.getter === null) return;
+    if (field.setter === null) return;
+    int getterFlags = field.getter.modifiers.flags | Modifiers.FLAG_ABSTRACT;
+    int setterFlags = field.setter.modifiers.flags | Modifiers.FLAG_ABSTRACT;
     if (getterFlags !== setterFlags) {
       final mismatchedFlags =
         new Modifiers.withFlags(null, getterFlags ^ setterFlags);
       compiler.reportMessage(
-          compiler.spanFromElement(member.getter),
+          compiler.spanFromElement(field.getter),
           MessageKind.GETTER_MISMATCH.error([mismatchedFlags]),
           api.Diagnostic.ERROR);
       compiler.reportMessage(
-          compiler.spanFromElement(member.setter),
+          compiler.spanFromElement(field.setter),
           MessageKind.SETTER_MISMATCH.error([mismatchedFlags]),
           api.Diagnostic.ERROR);
     }
   }
 
   reportErrorWithContext(Element errorneousElement,
                          MessageKind errorMessage,
                          Element contextElement,
                          MessageKind contextMessage) {
     compiler.reportMessage(
@@ skipping 2020 matching lines @@
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) {
     return library.find(name);
   }
 
   Element add(Element newElement) {
     throw "Cannot add an element in the top scope";
   }
   String toString() => '$element';
 }