pkg/front_end/testcases/regress/issue_29978.dart

// 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=2.9
foo(a, b) => null;

main() {
  foo(null, f() {});
}