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, c++20
10 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // constexpr auto operator[](difference_type n) const requires
13 //        all_random_access<Const, Views...>
14 
15 #include <ranges>
16 #include <cassert>
17 
18 #include "../types.h"
19 
20 constexpr bool test() {
21   int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};
22 
23   {
24     // random_access_range
25     std::ranges::zip_view v(SizedRandomAccessView{buffer}, std::views::iota(0));
26     auto it = v.begin();
27     assert(it[0] == *it);
28     assert(it[2] == *(it + 2));
29     assert(it[4] == *(it + 4));
30 
31     static_assert(std::is_same_v<decltype(it[2]), std::pair<int&, int>>);
32   }
33 
34   {
35     // contiguous_range
36     std::ranges::zip_view v(ContiguousCommonView{buffer}, ContiguousCommonView{buffer});
37     auto it = v.begin();
38     assert(it[0] == *it);
39     assert(it[2] == *(it + 2));
40     assert(it[4] == *(it + 4));
41 
42     static_assert(std::is_same_v<decltype(it[2]), std::pair<int&, int&>>);
43   }
44 
45   {
46     // non random_access_range
47     std::ranges::zip_view v(BidiCommonView{buffer});
48     auto iter = v.begin();
49     const auto canSubscript = [](auto&& it) { return requires { it[0]; }; };
50     static_assert(!canSubscript(iter));
51   }
52 
53   return true;
54 }
55 
56 int main(int, char**) {
57   test();
58   static_assert(test());
59 
60   return 0;
61 }
62