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// const charT& back() const; // constexpr since C++20
12// charT& back(); // constexpr since C++20
13
14#include <string>
15#include <cassert>
16
17#include "test_macros.h"
18#include "min_allocator.h"
19
20template <class S>
21TEST_CONSTEXPR_CXX20 void test(S s) {
22 const S& cs = s;
23 ASSERT_SAME_TYPE(decltype(s.back()), typename S::reference);
24 ASSERT_SAME_TYPE(decltype(cs.back()), typename S::const_reference);
25 LIBCPP_ASSERT_NOEXCEPT(s.back());
26 LIBCPP_ASSERT_NOEXCEPT(cs.back());
27 assert(&cs.back() == &cs[cs.size() - 1]);
28 assert(&s.back() == &s[cs.size() - 1]);
29 s.back() = typename S::value_type('z');
30 assert(s.back() == typename S::value_type('z'));
31}
32
33template <class S>
34TEST_CONSTEXPR_CXX20 void test_string() {
35 test(S("1"));
36 test(S("1234567890123456789012345678901234567890"));
37}
38
39TEST_CONSTEXPR_CXX20 bool test() {
40 test_string<std::string>();
41#if TEST_STD_VER >= 11
42 test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
43#endif
44
45 return true;
46}
47
48int main(int, char**) {
49 test();
50#if TEST_STD_VER > 17
51 static_assert(test());
52#endif
53
54 return 0;
55}
56

source code of libcxx/test/std/strings/basic.string/string.access/back.pass.cpp