blob: 47397adfe80c826b8638009b20171eef7bfbb45e [file] [log] [blame]
* 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
* NORM(T?) =
* let S be NORM(T)
* if S is a top type then S
* if S is Never then Null
* if S is Never* then Null
* if S is Null then Null
* if S is FutureOr<R> and R is nullable then S
* if S is FutureOr<R>* and R is nullable then FutureOr<R>
* if S is R? then R?
* if S is R* then R?
* else S?
* @description Checks that if NORM(T) is Null then NORM(T?) = Null
* @author
// Requirements=nnbd-strong
class A<X> {}
class B1<X> implements A<X> {}
class B2<X> implements A<X?> {}
class C1 extends B1<Null?> implements A<Null> {}
class C2 extends B1<Never?> implements A<Null> {}
main() {
new C1();
new C2();