84 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++0310 11// <string>12 13// void swap(basic_string& c)14// noexcept(!allocator_type::propagate_on_container_swap::value ||15// __is_nothrow_swappable<allocator_type>::value); // constexpr since C++2016//17// In C++17, the standard says that swap shall have:18// noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||19// allocator_traits<Allocator>::is_always_equal::value); // constexpr since C++2020 21// This tests a conforming extension22 23#include <string>24#include <utility>25#include <cassert>26 27#include "test_macros.h"28#include "test_allocator.h"29 30template <class T>31struct some_alloc {32 typedef T value_type;33 34 some_alloc() {}35 some_alloc(const some_alloc&);36 T* allocate(std::size_t);37 void deallocate(void*, unsigned) {}38 typedef std::true_type propagate_on_container_swap;39};40 41template <class T>42struct some_alloc2 {43 typedef T value_type;44 45 some_alloc2() {}46 some_alloc2(const some_alloc2&);47 T* allocate(std::size_t);48 void deallocate(void*, unsigned) {}49 50 typedef std::false_type propagate_on_container_swap;51 typedef std::true_type is_always_equal;52};53 54int main(int, char**) {55 {56 typedef std::string C;57 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");58 }59#if defined(_LIBCPP_VERSION)60 {61 typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;62 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");63 }64#endif // _LIBCPP_VERSION65 {66 typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;67#if TEST_STD_VER >= 1468 // In C++14, if POCS is set, swapping the allocator is required not to throw69 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");70#else71 static_assert(!noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");72#endif73 }74#if TEST_STD_VER >= 1475 {76 typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;77 // if the allocators are always equal, then the swap can be noexcept78 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");79 }80#endif81 82 return 0;83}84