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 // <string>
10 
11 //       reverse_iterator rbegin(); // constexpr since C++20
12 // const_reverse_iterator rbegin() const; // constexpr since C++20
13 
14 #include <string>
15 #include <cassert>
16 
17 #include "test_macros.h"
18 #include "min_allocator.h"
19 
20 template <class S>
21 TEST_CONSTEXPR_CXX20 void
22 test(S s)
23 {
24     const S& cs = s;
25     typename S::reverse_iterator b = s.rbegin();
26     typename S::const_reverse_iterator cb = cs.rbegin();
27     if (!s.empty())
28     {
29         assert(*b == s.back());
30     }
31     assert(b == cb);
32 }
33 
34 TEST_CONSTEXPR_CXX20 bool test() {
35   {
36     typedef std::string S;
37     test(S());
38     test(S("123"));
39   }
40 #if TEST_STD_VER >= 11
41   {
42     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
43     test(S());
44     test(S("123"));
45   }
46 #endif
47 
48   return true;
49 }
50 
51 int main(int, char**)
52 {
53   test();
54 #if TEST_STD_VER > 17
55   static_assert(test());
56 #endif
57 
58   return 0;
59 }
60