Opt-in to generate code for compile-time error. Only supported for SSA.

tests/compiler/dart2js/mock_compiler.dart

 // Copyright (c) 2012, 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.
 
 library mock_compiler;
 
 import "package:expect/expect.dart";
 import 'dart:async';
 import 'dart:collection';
 
@@ skipping 371 matching lines @@
                                     {bool verbose: false}) {
   return (uri, int begin, int end, String message, kind) {
     if (kind == api.Diagnostic.VERBOSE_INFO && !verbose) return;
     SourceFile sourceFile;
     if (uri == null) {
       sourceFile = new StringSourceFile.fromName('analysis', text);
     } else {
       sourceFile = compiler.sourceFiles[uri.toString()];
     }
     if (sourceFile != null && begin != null && end != null) {
-      print(sourceFile.getLocationMessage(message, begin, end));
+      print('${kind}: ${sourceFile.getLocationMessage(message, begin, end)}');
     } else {
-      print(message);
+      print('${kind}: $message');
     }
   };
 }
 
 class MockElement extends FunctionElementX {
   MockElement(Element enclosingElement)
       : super('', ElementKind.FUNCTION, Modifiers.EMPTY,
               enclosingElement);
 
   get node => null;
 
   parseNode(_) => null;
 
   bool get hasNode => false;
 }