Check for cyclic reference in typedefs

sdk/lib/_internal/compiler/implementation/warnings.dart

Index: sdk/lib/_internal/compiler/implementation/warnings.dart
diff --git a/sdk/lib/_internal/compiler/implementation/warnings.dart b/sdk/lib/_internal/compiler/implementation/warnings.dart
index 2fe05d76aa04f3dcff66cb2855eee67957756972..64fc57ced51aedf736aaef2083cfdef864243d8e 100644
--- a/sdk/lib/_internal/compiler/implementation/warnings.dart
+++ b/sdk/lib/_internal/compiler/implementation/warnings.dart
@@ -391,6 +391,17 @@ class MessageKind {
   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.');