1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03
// <string>
// void swap(basic_string& c)
// noexcept(!allocator_type::propagate_on_container_swap::value ||
// __is_nothrow_swappable<allocator_type>::value); // constexpr since C++20
//
// In C++17, the standard says that swap shall have:
// noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
// allocator_traits<Allocator>::is_always_equal::value); // constexpr since C++20
// This tests a conforming extension
#include <string>
#include <utility>
#include <cassert>
#include "test_macros.h"
#include "test_allocator.h"
template <class T>
struct some_alloc {
typedef T value_type;
some_alloc() {}
some_alloc(const some_alloc&);
T* allocate(std::size_t);
void deallocate(void*, unsigned) {}
typedef std::true_type propagate_on_container_swap;
};
template <class T>
struct some_alloc2 {
typedef T value_type;
some_alloc2() {}
some_alloc2(const some_alloc2&);
T* allocate(std::size_t);
void deallocate(void*, unsigned) {}
typedef std::false_type propagate_on_container_swap;
typedef std::true_type is_always_equal;
};
int main(int, char**) {
{
typedef std::string C;
static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
}
#if defined(_LIBCPP_VERSION)
{
typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;
static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
}
#endif // _LIBCPP_VERSION
{
typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
#if TEST_STD_VER >= 14
// In C++14, if POCS is set, swapping the allocator is required not to throw
static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
#else
static_assert(!noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
#endif
}
#if TEST_STD_VER >= 14
{
typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
// if the allocators are always equal, then the swap can be noexcept
static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
}
#endif
return 0;
}
|
