Check for cyclic reference in typedefs

sdk/lib/_internal/compiler/implementation/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.
 
 part of dart2js;
 
 const DONT_KNOW_HOW_TO_FIX = "";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 373 matching lines @@
 
   static const MessageKind CANNOT_INSTANTIATE_TYPEDEF = const MessageKind(
       'Error: Cannot instantiate typedef "#{typedefName}".');
 
   static const MessageKind CANNOT_INSTANTIATE_TYPE_VARIABLE = const MessageKind(
       'Error: Cannot instantiate type variable "#{typeVariableName}".');
 
   static const MessageKind CYCLIC_TYPE_VARIABLE = const MessageKind(
       'Warning: Type variable "#{typeVariableName}" is a supertype of itself.');
 
+  static const CYCLIC_TYPEDEF = const MessageKind(

[karlklose, 2013/09/17 08:56:15]

Please add a '.' to the end of the messages.

I think the error messages should point out the problem, like "a typedef can't
refer to itself." and you should provide a howToFix.

Also see Kathy and Peter's comments here:
https://codereview.chromium.org/23456030/

[Johnni Winther, 2013/09/18 07:57:15]

Done.

+      "Error: Typedef #{typedefName} refers to itself");
+
+  static const CYCLIC_TYPEDEF_ONE = const MessageKind(
+      "Error: Typedef #{typedefName} refers to itself through "
+      "typedef #{otherTypedefName}");
+
+  static const CYCLIC_TYPEDEF_TYPEVAR = const MessageKind(
+      "Internal Error: Recursive type variable bounds are not currently "

[karlklose, 2013/09/17 08:56:15]

Please remove 'currently'.

[Johnni Winther, 2013/09/18 07:57:15]

Done.

+      "supported on typedefs.");
+
   static const MessageKind CLASS_NAME_EXPECTED = const MessageKind(
       'Error: Class name expected.');
 
   static const MessageKind CANNOT_EXTEND = const MessageKind(
       'Error: "#{type}" cannot be extended.');
 
   static const MessageKind CANNOT_IMPLEMENT = const MessageKind(
       'Error: "#{type}" cannot be implemented.');
 
   static const MessageKind DUPLICATE_EXTENDS_IMPLEMENTS = const MessageKind(
@@ skipping 618 matching lines @@
 
 class CompileTimeConstantError extends Diagnostic {
   CompileTimeConstantError(MessageKind kind, Map arguments, bool terse)
     : super(kind, arguments, terse);
 }
 
 class CompilationError extends Diagnostic {
   CompilationError(MessageKind kind, Map arguments, bool terse)
     : super(kind, arguments, terse);
 }