Language/Generics/typedef_A08_t03.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.

/// @assertion A generic type alias is a declaration [D] of one of the following
/// forms:
///   m typedef id<X1 extends B1, . . . , Xs extends Bs> = T;
///   m typedef S? id<X1 extends B1, . . . , Xs extends Bs>(
///     T1 p1, . . . , Tn pn, [Tn+1 pn+1, . . . , Tn+k pn+k]);
///   m typedef S? id<X1 extends B1, . . . , Xs extends Bs>(
///     T1 p1, . . . , Tn pn, {Tn+1 pn+1, . . . , Tn+k pn+k});
/// where [m] is derived from metadata, [T] is a type, and [S?] is a type or the
/// empty string. Let [S0] be [S?] if it is a type, otherwise let [S0] be
/// [dynamic]. The associated type of [D], call it [F], is, respectively:
///   T
///   S0 Function(T1, . . . , Tn, [Tn+1, . . . , Tn+k])
///   S0 Function(T1, . . . , Tn, {Tn+1 xn+1, . . . , Tn+k xn+k})
/// ...
/// Moreover, let [T1], . . . , [Tl] be types and let [U] be the parameterized
/// type id<T1, . . . , Tl> in a location where [id] denotes [D]. ... It is a
/// compile-time error if [U] is not well-bounded
/// @description Checks that compile error is thrown if [U] is not well-bounded.
/// @Issue 36959, 37050
/// @author iarkh@unipro.ru

class A<X extends A<X>> {}

typedef AAlias<T extends A<T>> = T Function<T1 extends T>();

main() {
  AAlias             a1;
  AAlias<A>          a2;
  AAlias<A<Never>>    a3;
  AAlias<A<dynamic>> a4;
  AAlias<A<Object?>> a5;
  AAlias<A<int>>     a6;
//       ^^^^^^
// [analyzer] unspecified
// [cfe] unspecified
  AAlias<int>        a7;
  //     ^^^
  // [analyzer] COMPILE_TIME_ERROR.TYPE_ARGUMENT_NOT_MATCHING_BOUNDS
  //                 ^
  // [cfe] Type argument 'int' doesn't conform to the bound 'A<T>' of the type variable 'T' on 'AAlias'.
  AAlias<Null>       a8;
  //     ^^^^
  // [analyzer] COMPILE_TIME_ERROR.TYPE_ARGUMENT_NOT_MATCHING_BOUNDS
  //                 ^
  // [cfe] Type argument 'Null' doesn't conform to the bound 'A<T>' of the type variable 'T' on 'AAlias'.
  AAlias<dynamic>    a9;
}