// Copyright (c) 2020, 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.

/**
 * @assertion We say that a type T0 is a subtype of a type T1 (written T0 <: T1)
 * when:
 * Left Null: if T0 is Null then:
 * - if T1 is a type variable (promoted or not) the query is false
 * - If T1 is FutureOr<S> for some S, then the query is true iff Null <: S.
 * - If T1 is Null, S? or S* for some S, then the query is true.
 * - Otherwise, the query is false
 * @description Check that if type T0 is Null and If T1 is S? then T0 is
 * subtype of T1
 * @author sgrekhov@unipro.ru
 */

class S {
  const S();
}

Null t0Instance = null;
S? t1Instance = new S();

const t1Default = const S();

//# @T0 = Null
//# @T1 = S?