Language/Types/Function_Types/subtype_named_args_t04.dart

// Copyright (c) 2011, 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 The function type (T1, ... Tn, {Tx1 x1, ..., Txk xk}) -> T is a
 * subtype of the function type (S1, ..., Sn, {Sy1 y1, ..., Sym ym }) -> S, if
 * all of the following conditions are met:
 * 1. Either
 *    • S is void, Or
 *    • T ⇐⇒ S.
 * 2. ∀i ∈ 1..n, Ti ⇐⇒ Si .
 * 3. k ≥ m and yi ∈ {x1 , ..., xk }, i ∈ 1..m.
 * 4. For all yi ∈ {y1 , ..., ym }, yi = xj ⇒ Tj ⇐⇒ Si.
 * @description Checks that this statement is true for quite complex function
 * types: non-dynamic return type and a bunch of required and named optional
 * parameters.
 * @author rodionov
 * @issue 42648
 */
// Requirements=nnbd-strong
import "../../../Utils/expect.dart";

class A {}
class A1 {}
class A2 {}
class B implements A, A1, A2 {}
class C implements B {}
class D implements C {}

typedef B func(Object o);
typedef B t1(int i, B b, Map<int, num> m, var x, {
  required var ox, required B ob, required List<num> ol, required bool obool});

B f1(int i, B b, Map<int, num> m, var x, {
  required extraParam, required bool obool, required var ox, required D ob, required List<num>? ol}) => new B();
D f2(int i, D b, Map<int, int> m, func x, {
  required func ox, required D ob, required List<int> ol, required bool obool}) => new D();
C f3(num i, A b, Map<Object, Object> m, var x, {
  required var ox, required extraParam, required A2 ob, required List ol, required Object obool}) => new C();
C f4(num i, A b, Map<Object, Object> m, var x, {
  required var ox, required A2 ob, required List ol, required bool obool, required A xx, required B yy}) => new C();
C f5(int i, A b, Map<Object, Object> m, var x, {
  required ox, required B ob, required List ol, required obool}) => new C();

main() {
  Expect.isFalse(f1 is t1);
  Expect.isFalse(f2 is t1);
  Expect.isFalse(f3 is t1);
  Expect.isFalse(f4 is t1);
  Expect.isTrue(f5 is t1);
}