Fix leg assert and NPE to make BB green.

frog/leg/elements/elements.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.
 
 #library('elements');
 
 #import('../tree/tree.dart');
 #import('../scanner/scannerlib.dart');
 #import('../leg.dart');  // TODO(karlklose): we only need type.
 #import('../util/util.dart');
@@ skipping 407 matching lines @@
   position() {
     // The getter and setter may be defined in two different
     // compilation units.  However, we know that one of them is
     // non-null and defined in the same compilation unit as the
     // abstract element.
     //
     // We need to make sure that the position returned is relative to
     // the compilation unit of the abstract element.
     if (getter !== null && getter.enclosingElement === enclosingElement) {
       return getter.position();
-    } else {
+    } else if (setter != null) {
+      // TODO(ahe): checking for null should not be necessary.

[ngeoffray, 2012/03/13 20:08:24]

Told you so :-)

[ahe, 2012/03/14 09:22:08]

Why is this happening? I think this is a symptom fix, that masks a different
bug.

The method [position] may not return null. That will lead to a crash in a
different place.

Take a look at this code in ContainerElement.addGetterOrSetter:

      AbstractFieldElement field = new AbstractFieldElement(element.name, this);
      addMember(field, listener);
      if (element.kind == ElementKind.GETTER) {
        field.getter = element;
      } else {
        field.setter = element;
      }

I think the problem is that [addMember] is called before the
AbstractFieldElement is set up correctly, and you will find that the error
message is not indicating the correct location.

       return setter.position();
     }

[floitsch, 2012/03/14 09:03:09]

else { return null; }

   }
 }
 
 /** DEPRECATED. */
 Type getType(TypeAnnotation typeAnnotation,
              Compiler compiler,
              LibraryElement library) {
   // TODO(karlklose,ngeoffray): This method should be removed and the
   // information should be computed by the resolver.
 
@@ skipping 432 matching lines @@
     return result;
   }
 
   Node parseNode(DiagnosticListener l) => statement;
 
   bool get isSwitch() => statement is SwitchStatement;
 
   Token position() => statement.getBeginToken();
   String toString() => statement.toString();
 }