| // Copyright (c) 2021, 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 Allow generic function types as type arguments and bounds |
| * |
| * The language disallows generic function types as type arguments and bounds. |
| * |
| * late List<T Function<T>(T)> idFunctions; // INVALID. |
| * var callback = [foo<T>(T value) => value]; // Inferred as above, then invalid. |
| * late S Function<S extends T Function<T>(T)>(S) f; // INVALID. |
| * |
| * We remove that restriction, so a type argument and a bound can be a generic |
| * function type. |
| * |
| * This requires no new syntax, and in some cases only the removal of a single |
| * check. There might be some platforms where the implementation currently |
| * assumes that generic function types cannot occur as the value of type |
| * variables (an proof-of-concept attempt hit an assert in the VM). Such |
| * assumptions will need to be flushed out with tests and fixed. |
| * |
| * Because we already infer List<T Function<T>(T)> in the code above, this |
| * change will not affect type inference, it will just make the inferred type |
| * not be an error afterwards. |
| * |
| * We do not expect the removal of this restriction to affect the feasibility of |
| * type inference. After all, it's already possible to have a generic function |
| * type occurring covariantly in a type argument, like List<T Function<T>(T) |
| * Function()>. |
| * @description Checks that generic function can be an old-style function type |
| * alias argument and bound. |
| * @Issue 45313, 45718 |
| * @author iarkh@unipro.ru |
| */ |
| // SharedOptions=--enable-experiment=generic-metadata |
| |
| import "../../Utils/expect.dart"; |
| |
| typedef void TEST<T extends TT Function<TT>()>(T t); |
| |
| void testme<T extends TT Function<TT>()>(T t) {} |
| void testme1(T Function<T>() t) {} |
| |
| main() { |
| // See https://github.com/dart-lang/sdk/issues/45718 evaluation for more details |
| |
| TEST t = testme; |
| TEST t1 = testme1; |
| |
| Expect.isFalse(testme is TEST); |
| Expect.isTrue(testme1 is TEST); |
| Expect.isTrue(t is TEST); |
| Expect.isTrue(t1 is TEST); |
| Expect.isTrue(t1 is TEST); |
| } |