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 // <tuple>
10
11 // template <class... Types> class tuple;
12
13 // template <class... Types>
14 // void swap(const tuple<Types...>& x, const tuple<Types...>& y);
15
16 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
17
18 #include <tuple>
19 #include <cassert>
20
21 struct S {
22 int* calls;
swap(S & a,S & b)23 friend constexpr void swap(S& a, S& b) {
24 *a.calls += 1;
25 *b.calls += 1;
26 }
27 };
28 struct CS {
29 int* calls;
swap(const CS & a,const CS & b)30 friend constexpr void swap(const CS& a, const CS& b) {
31 *a.calls += 1;
32 *b.calls += 1;
33 }
34 };
35
36 static_assert(std::is_swappable_v<std::tuple<>>);
37 static_assert(std::is_swappable_v<std::tuple<S>>);
38 static_assert(std::is_swappable_v<std::tuple<CS>>);
39 static_assert(std::is_swappable_v<std::tuple<S&>>);
40 static_assert(std::is_swappable_v<std::tuple<CS, S>>);
41 static_assert(std::is_swappable_v<std::tuple<CS, S&>>);
42 static_assert(std::is_swappable_v<const std::tuple<>>);
43 static_assert(!std::is_swappable_v<const std::tuple<S>>);
44 static_assert(std::is_swappable_v<const std::tuple<CS>>);
45 static_assert(std::is_swappable_v<const std::tuple<S&>>);
46 static_assert(!std::is_swappable_v<const std::tuple<CS, S>>);
47 static_assert(std::is_swappable_v<const std::tuple<CS, S&>>);
48
test()49 constexpr bool test() {
50 int cs_calls = 0;
51 int s_calls = 0;
52 S s1{&s_calls};
53 S s2{&s_calls};
54 const std::tuple<CS, S&> t1 = {CS{&cs_calls}, s1};
55 const std::tuple<CS, S&> t2 = {CS{&cs_calls}, s2};
56 swap(t1, t2);
57 assert(cs_calls == 2);
58 assert(s_calls == 2);
59
60 return true;
61 }
62
main(int,char **)63 int main(int, char**) {
64 test();
65 static_assert(test());
66
67 return 0;
68 }
69