We inline List allocations in dart2js to get the right behavior when the passed length is null. Thi…

sdk/lib/_internal/compiler/implementation/resolution/members.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.
 
 part of resolution;
 
 abstract class TreeElements {
   Element get currentElement;
   Setlet<Node> get superUses;
 
@@ skipping 306 matching lines @@
     while (!originParameters.isEmpty) {
       Element originParameter = originParameters.head;
       Element patchParameter = patchParameters.head;
       // Hack: Use unparser to test parameter equality. This only works because
       // we are restricting patch uses and the approach cannot be used
       // elsewhere.
       String originParameterText =
           originParameter.parseNode(compiler).toString();
       String patchParameterText =
           patchParameter.parseNode(compiler).toString();
-      if (originParameterText != patchParameterText) {
+      if (originParameterText != patchParameterText
+          // We special case the list constructor because of the
+          // optional parameter.
+          && origin != compiler.unnamedListConstructor) {

[ahe, 2013/12/10 18:57:44]

Why is a special case needed?

Why can't the public code and the patch file agree?

[ngeoffray, 2013/12/10 22:08:31]

The patch code says:
factory List([int length = const _Internal()])

The public code says:
factory List([int length]).

         compiler.reportError(
             originParameter.parseNode(compiler),
             MessageKind.PATCH_PARAMETER_MISMATCH,
             {'methodName': origin.name,
              'originParameter': originParameterText,
              'patchParameter': patchParameterText});
         compiler.reportMessage(
             compiler.spanFromSpannable(patchParameter),
             MessageKind.PATCH_POINT_TO_PARAMETER.error(
                 {'parameterName': patchParameter.name}),
@@ skipping 4429 matching lines @@
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }
 
 /// Looks up [name] in [scope] and unwraps the result.
 Element lookupInScope(Compiler compiler, Node node,
                       Scope scope, String name) {
   return Elements.unwrap(scope.lookup(name), compiler, node);
 }