pkg/front_end/testcases/variance/mixin_type_parameter_modifier.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 A {}

mixin B<inout X, out Y, in Z> on A {}

main() {}