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 // UNSUPPORTED: c++03, c++11, c++14, c++17
10
11 // constexpr decltype(auto) operator[](iter_difference_t<I> n) const
12 // requires random_access_iterator<I>;
13
14 #include <iterator>
15
16 #include "test_macros.h"
17 #include "test_iterators.h"
18
19 template<class Iter>
20 concept SubscriptEnabled = requires(Iter& iter) {
21 iter[1];
22 };
23
test()24 constexpr bool test() {
25 int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
26
27 {
28 std::counted_iterator iter(random_access_iterator<int*>{buffer}, 8);
29 for (int i = 1; i < 9; ++i)
30 assert(iter[i - 1] == i);
31 }
32 {
33 std::counted_iterator iter(contiguous_iterator<int*>{buffer}, 8);
34 for (int i = 1; i < 9; ++i)
35 assert(iter[i - 1] == i);
36 }
37
38 {
39 const std::counted_iterator iter(random_access_iterator<int*>{buffer}, 8);
40 assert(iter[0] == 1);
41 }
42 {
43 const std::counted_iterator iter(contiguous_iterator<int*>{buffer}, 8);
44 assert(iter[7] == 8);
45 }
46
47 {
48 static_assert( SubscriptEnabled<std::counted_iterator<random_access_iterator<int*>>>);
49 static_assert(!SubscriptEnabled<std::counted_iterator<bidirectional_iterator<int*>>>);
50 }
51
52 return true;
53 }
54
main(int,char **)55 int main(int, char**) {
56 test();
57 static_assert(test());
58
59 return 0;
60 }
61