anchor.diff:      var outputBuffer = new StringBuffer();
       var response = new WorkResponse()..exitCode = 0;
       try {
  -      fe.InitializedCompilerState previousStateToPass;
  +      fe.InitializedCompilerState? previousStateToPass;
         if (request.arguments.contains("--reuse-compiler-result")) {
           previousStateToPass = previousState;
         } else {
  
positive.code: // Copyright (c) 2017, 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.
  
  // @dart = 2.8
  
  /// A tool that invokes the CFE to compute kernel summary files.
  ///
  
negative.code: 
  /// [sendPort] may be passed in when started in an isolate. If provided, it is
  /// used for bazel worker communication instead of stdin/stdout.
  main(List<String> args, SendPort? sendPort) async {
    args = preprocessArgs(args);
  
    if (args.contains('--persistent_worker')) {
  