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 // reference operator[](size_type); // constexpr in C++17
12 // Libc++ marks it as noexcept
13 
14 #include <array>
15 #include <cassert>
16 
17 #include "test_macros.h"
18 
19 TEST_CONSTEXPR_CXX17 bool tests()
20 {
21     {
22         typedef double T;
23         typedef std::array<T, 3> C;
24         C c = {1, 2, 3.5};
25         LIBCPP_ASSERT_NOEXCEPT(c[0]);
26         ASSERT_SAME_TYPE(C::reference, decltype(c[0]));
27         C::reference r1 = c[0];
28         assert(r1 == 1);
29         r1 = 5.5;
30         assert(c.front() == 5.5);
31 
32         C::reference r2 = c[2];
33         assert(r2 == 3.5);
34         r2 = 7.5;
35         assert(c.back() == 7.5);
36     }
37 
38     // Test operator[] "works" on zero sized arrays
39     {
40         {
41             typedef double T;
42             typedef std::array<T, 0> C;
43             C c = {};
44             LIBCPP_ASSERT_NOEXCEPT(c[0]);
45             ASSERT_SAME_TYPE(C::reference, decltype(c[0]));
46             if (c.size() > (0)) { // always false
47               C::reference r = c[0];
48               (void)r;
49             }
50         }
51         {
52             typedef double T;
53             typedef std::array<const T, 0> C;
54             C c = {};
55             LIBCPP_ASSERT_NOEXCEPT(c[0]);
56             ASSERT_SAME_TYPE(C::reference, decltype(c[0]));
57             if (c.size() > (0)) { // always false
58               C::reference r = c[0];
59               (void)r;
60             }
61         }
62     }
63 
64     return true;
65 }
66 
67 int main(int, char**)
68 {
69     tests();
70 #if TEST_STD_VER >= 17
71     static_assert(tests(), "");
72 #endif
73     return 0;
74 }
75