Check const expressions for malformed types.

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 509 matching lines @@
 
   static const DualKind TYPE_VARIABLE_WITHIN_STATIC_MEMBER = const DualKind(
       error: const MessageKind(
           "Error: Cannot refer to type variable '#{typeVariableName}' "
           "within a static member."),
       warning: const MessageKind(
           "Warning: Cannot refer to type variable '#{typeVariableName}' "
           "within a static member."));
 
   static const MessageKind TYPE_VARIABLE_IN_CONSTANT = const MessageKind(
-      "Error: Cannot refer to type variable in constant.");
+      "Error: Constant expressions can't refer to type variables.",
+      howToFix: "Try removing the type variable or replacing it with a "
+                "concrete type.",
+      examples: const ["""
+class C<T> {
+  const C();
+
+  m(T t) => const C<T>();
+}
+
+void main() => new C().m(null);  
+"""
+]);
+
 
   static const MessageKind INVALID_TYPE_VARIABLE_BOUND = const MessageKind(
       "Warning: '#{typeArgument}' is not a subtype of bound '#{bound}' for "
       "type variable '#{typeVariable}' of type '#{thisType}'.",
       howToFix: "Try to change or remove the type argument.",
       examples: const ["""
 class C<T extends num> {}
 
 // 'String' is not a valid instantiation of T with bound num.'.
 main() => new C<String>();
@@ skipping 980 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);
 }