| // Copyright (c) 2019, 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.md file. | 
 |  | 
 | // Regression test for failure on CFE null-aware encoding. | 
 |  | 
 | class Class { | 
 |   Map<String, Set<String>>? map; | 
 |  | 
 |   List<String> method(String node, Set<String> set) => set.add(node) | 
 |       ? [node, ...?map![node]?.expand((node) => method(node, set))?.toList()] | 
 |       : []; | 
 | } | 
 |  | 
 | main(args) { | 
 |   if (args != null && args.isNotEmpty) new Class().method('', <String>{}); | 
 | } |