1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// REQUIRES: std-at-least-c++26
10
11// <functional>
12
13// class reference_wrapper
14
15// [refwrap.comparisons], comparisons
16
17// friend constexpr auto operator<=>(reference_wrapper, const T&); // Since C++26
18
19#include <cassert>
20#include <concepts>
21#include <functional>
22
23#include "test_comparisons.h"
24#include "test_macros.h"
25
26// Test SFINAE.
27
28static_assert(HasOperatorSpaceship<std::reference_wrapper<StrongOrder>, int>);
29static_assert(HasOperatorSpaceship<std::reference_wrapper<WeakOrder>, int>);
30static_assert(HasOperatorSpaceship<std::reference_wrapper<PartialOrder>, int>);
31
32static_assert(!HasOperatorSpaceship<std::reference_wrapper<NonComparable>, int>);
33
34// Test comparisons.
35
36template <typename T, typename Order>
37constexpr void test() {
38 T t{47};
39
40 T bigger{94};
41 T smaller{82};
42
43 T unordered{std::numeric_limits<int>::min()};
44
45 // Identical contents
46 {
47 std::reference_wrapper<T> rw1{t};
48 assert(testOrder(rw1, t, Order::equivalent));
49 }
50 // Less
51 {
52 std::reference_wrapper<T> rw1{smaller};
53 assert(testOrder(rw1, bigger, Order::less));
54 }
55 // Greater
56 {
57 std::reference_wrapper<T> rw1{bigger};
58 assert(testOrder(rw1, smaller, Order::greater));
59 }
60 // Unordered
61 if constexpr (std::same_as<T, PartialOrder>) {
62 std::reference_wrapper<T> rw1{bigger};
63 assert(testOrder(rw1, unordered, Order::unordered));
64 }
65}
66
67constexpr bool test() {
68 test<int, std::strong_ordering>();
69 test<StrongOrder, std::strong_ordering>();
70 test<int, std::weak_ordering>();
71 test<WeakOrder, std::weak_ordering>();
72 test<int, std::partial_ordering>();
73 test<PartialOrder, std::partial_ordering>();
74
75 // `LessAndEqComp` does not have `operator<=>`. Ordering is synthesized based on `operator<`
76 test<LessAndEqComp, std::weak_ordering>();
77
78 return true;
79}
80
81int main(int, char**) {
82 test();
83 static_assert(test());
84
85 return 0;
86}
87

source code of libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.const_ref.pass.cpp