// Copyright (c) 2018, 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
///
/// @description Check that if type T0 is a subtype of a type T1, then instance
/// of T0 can be used as a return value of type T1
/// @author sgrekhov@unipro.ru
///
/// This test is generated from left_null_A05.dart and 
/// return_value_x01.dart.
/// Don't modify it. If you want to change this test, change one of the files 
/// above and then run generator.dart to regenerate the tests.


class S {
  const S();
}

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

const t1Default = const S();


S? returnValueFunc() => t0Instance;

class ReturnValueTest {
  static S? staticTestMethod() => t0Instance;

  S? testMethod() => t0Instance;

  S? get testGetter => t0Instance;
}

main() {
  S? returnValueLocalFunc() => t0Instance;

  returnValueFunc();
  returnValueLocalFunc();

  ReturnValueTest.staticTestMethod();

  new ReturnValueTest().testMethod();
  new ReturnValueTest().testGetter;

}