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 // <array>
10 
11 // template <class T, size_t N> void swap(array<T,N>& x, array<T,N>& y);
12 
13 #include <array>
14 #include <cassert>
15 
16 #include "test_macros.h"
17 
18 struct NonSwappable {
19     TEST_CONSTEXPR NonSwappable() { }
20 private:
21     NonSwappable(NonSwappable const&);
22     NonSwappable& operator=(NonSwappable const&);
23 };
24 
25 template <class Tp>
26 decltype(swap(std::declval<Tp>(), std::declval<Tp>()))
27 can_swap_imp(int);
28 
29 template <class Tp>
30 std::false_type can_swap_imp(...);
31 
32 template <class Tp>
33 struct can_swap : std::is_same<decltype(can_swap_imp<Tp>(0)), void> { };
34 
35 TEST_CONSTEXPR_CXX20 bool tests()
36 {
37     {
38         typedef double T;
39         typedef std::array<T, 3> C;
40         C c1 = {1, 2, 3.5};
41         C c2 = {4, 5, 6.5};
42         swap(c1, c2);
43         assert(c1.size() == 3);
44         assert(c1[0] == 4);
45         assert(c1[1] == 5);
46         assert(c1[2] == 6.5);
47         assert(c2.size() == 3);
48         assert(c2[0] == 1);
49         assert(c2[1] == 2);
50         assert(c2[2] == 3.5);
51     }
52     {
53         typedef double T;
54         typedef std::array<T, 0> C;
55         C c1 = {};
56         C c2 = {};
57         swap(c1, c2);
58         assert(c1.size() == 0);
59         assert(c2.size() == 0);
60     }
61     {
62         typedef NonSwappable T;
63         typedef std::array<T, 0> C0;
64         static_assert(can_swap<C0&>::value, "");
65         C0 l = {};
66         C0 r = {};
67         swap(l, r);
68 #if TEST_STD_VER >= 11
69         static_assert(noexcept(swap(l, r)), "");
70 #endif
71     }
72 #if TEST_STD_VER >= 11
73     {
74         // NonSwappable is still considered swappable in C++03 because there
75         // is no access control SFINAE.
76         typedef NonSwappable T;
77         typedef std::array<T, 42> C1;
78         static_assert(!can_swap<C1&>::value, "");
79     }
80 #endif
81 
82     return true;
83 }
84 
85 int main(int, char**)
86 {
87     tests();
88 #if TEST_STD_VER >= 20
89     static_assert(tests(), "");
90 #endif
91     return 0;
92 }
93