Check for non-final field in the face of const constructors.

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 264 matching lines @@
       'Error: "super" call arguments and constructor parameters do not match.');
 
   static const MessageKind NO_MATCHING_CONSTRUCTOR_FOR_IMPLICIT =
       const MessageKind(
           'Error: Implicit "super" call arguments and constructor parameters '
           'do not match.');
 
   static const MessageKind CONST_CALLS_NON_CONST = const MessageKind(
       'Error: "const" constructor cannot call a non-const constructor.');
 
+  static const MessageKind CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS =
+      const MessageKind(
+          "Error: Can't declare constructor 'const' on class #{className} "
+          "because the class contains non-final instance fields.",
+          howToFix: "Try making all fields final.",
+          examples: const ["""
+class C {
+  // 'a' must be declared final to allow for the const constructor.
+  var a;
+  const C(this.a);
+}
+
+main() => new C(0);"""]);
+
+  static const MessageKind CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_FIELD =
+      const MessageKind('Info: This non-final field prevents using const '
+                        'constructors.');
+
+  static const MessageKind CONST_CONSTRUCTOR_WITH_NONFINAL_FIELDS_CONSTRUCTOR =
+      const MessageKind('Info: This const constructor is not allowed due to '
+                        'non-final fields.');
+
+
   static const MessageKind INITIALIZING_FORMAL_NOT_ALLOWED = const MessageKind(
       'Error: Initializing formal parameter only allowed in generative '
       'constructor.');
 
   static const MessageKind INVALID_PARAMETER = const MessageKind(
       'Error: Cannot resolve parameter.');
 
   static const MessageKind NOT_INSTANCE_FIELD = const MessageKind(
       'Error: "#{fieldName}" is not an instance field.');
 
@@ skipping 752 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);
 }