Implement cycle-checking and code generation for redirecting constructors.

frog/leg/warnings.dart

 // Copyright (c) 2011, 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.
 
 class MessageKind {
   final String template;
   const MessageKind(this.template);
 
   static final GENERIC = const MessageKind('#{1}');
 
@@ skipping 50 matching lines @@
   static final ALREADY_INITIALIZED = const MessageKind(
       '#{1} was already initialized here');
   static final INIT_STATIC_FIELD = const MessageKind(
       'cannot initialize static field #{1}');
   static final NOT_A_FIELD = const MessageKind(
       '#{1} is not a field');
   static final CONSTRUCTOR_CALL_EXPECTED = const MessageKind(
       "only call to 'this' or 'super' constructor allowed");
   static final INVALID_FOR_IN = const MessageKind(
       'Invalid for-in variable declaration.');
-  static final REDIRECTING_CTOR_HAS_INITIALIZER = const MessageKind(
+  static final REDIRECTING_CONSTRUCTOR_CYCLE = const MessageKind(
+     'cyclic constructor redirection');
+  static final REDIRECTING_CONSTRUCTOR_HAS_BODY = const MessageKind(
+     'redirecting constructor cannot have a body');
+  static final REDIRECTING_CONSTRUCTOR_HAS_INITIALIZER = const MessageKind(
       'redirecting constructor cannot have other initializers');
   static final SUPER_INITIALIZER_IN_OBJECT = const MessageKind(
       "'Object' cannot have a super initializer");
   static final DUPLICATE_SUPER_INITIALIZER = const MessageKind(
       'cannot have more than one super initializer');
   static final NO_MATCHING_CONSTRUCTOR = const MessageKind(
       'no matching constructor found');
   static final NO_CONSTRUCTOR = const MessageKind(
       '#{1} is a #{2}, not a constructor');
   static final FIELD_PARAMETER_NOT_ALLOWED = const MessageKind(
@@ skipping 66 matching lines @@
   String toString() => message.toString();
 }
 
 class CompileTimeConstantError {
   final Message message;
   CompileTimeConstantError.message(this.message);
   CompileTimeConstantError(MessageKind kind, List<Type> arguments)
     : message = new Message(kind, arguments);
   String toString() => message.toString();
 }