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

lib/compiler/implementation/resolver.dart

Index: lib/compiler/implementation/resolver.dart
diff --git a/lib/compiler/implementation/resolver.dart b/lib/compiler/implementation/resolver.dart
index 246a546edf7ae8b40d13e80b57ae7a63b3775156..b0e1e474d685ce335bbf39cacd89887357800bd7 100644
--- a/lib/compiler/implementation/resolver.dart
+++ b/lib/compiler/implementation/resolver.dart
@@ -254,20 +254,38 @@ class ResolverTask extends CompilerTask {
   }
 
   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);
     }