pkg/front_end/testcases/regress/issue_36669.dart

// 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 file.
// @dart=2.9
class NoUnnamedConstructor {
  NoUnnamedConstructor._();
}

class MixMeIn {}

class Foo extends NoUnnamedConstructor with MixMeIn {}