Fix analyzer's treatment of mixin constructors.

pkg/analyzer/lib/src/generated/error.dart

 // Copyright (c) 2014, 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 engine.error;
 
 import 'dart:collection';
 import 'java_core.dart';
 import 'source.dart';
 import 'scanner.dart' show Token;
@@ skipping 1404 matching lines @@
    * 9.1 Mixin Application: It is a compile-time error if the with clause of a
    * mixin application <i>C</i> includes a deferred type expression.
    *
    * @param typeName the name of the type that cannot be extended
    * @see #EXTENDS_DEFERRED_CLASS
    * @see #IMPLEMENTS_DEFERRED_CLASS
    */
   static const CompileTimeErrorCode MIXIN_DEFERRED_CLASS = const CompileTimeErrorCode('MIXIN_DEFERRED_CLASS', "This class cannot mixin the deferred class '{0}'");
 
   /**
+   * Not yet in the spec, but consistent with VM behavior.  It is a
+   * compile-time error if all of the constructors of a mixin's base class have
+   * at least one optional parameter (since only constructors that lack
+   * optional parameters can be forwarded to the mixin).  See
+   * https://code.google.com/p/dart/issues/detail?id=15101#c4
+   */
+  static const CompileTimeErrorCode MIXIN_HAS_NO_CONSTRUCTORS =
+      const CompileTimeErrorCode('MIXIN_HAS_NO_CONSTRUCTORS',
+          "No constructors could be created for this class, since all the "
+          "constructors in the base class have at least one optional "
+          "parameter.");

[Brian Wilkerson, 2014/11/07 16:59:32]

I find this message to be confusing and think that users will too. The "this
class" refers to the class containing the mixins, but we're not creating
constructors for that class, we're creating constructors for the implicit
superclass of that class.

[Paul Berry, 2014/11/07 17:31:01]

Good point.  I've changed it to "This mixin application is invalid because all
of the constructors in the base class '{0}' have optional parameters."

+
+  /**
    * 9 Mixins: It is a compile-time error if a mixin is derived from a class
    * whose superclass is not Object.
    *
    * @param typeName the name of the mixin that is invalid
    */
   static const CompileTimeErrorCode MIXIN_INHERITS_FROM_NOT_OBJECT = const CompileTimeErrorCode('MIXIN_INHERITS_FROM_NOT_OBJECT', "The class '{0}' cannot be used as a mixin because it extends a class other than Object");
 
   /**
    * 12.2 Null: It is a compile-time error for a class to attempt to extend or
    * implement Null.
@@ skipping 2589 matching lines @@
    * Initialize a newly created error code to have the given [name].
    */
   const TodoCode(String name) : super(name, "{0}");
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.INFO;
 
   @override
   ErrorType get type => ErrorType.TODO;
 }