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
10
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);
16 //
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);
20
21 // This tests a conforming extension
22
23 #include <string>
24 #include <utility>
25 #include <cassert>
26
27 #include "test_macros.h"
28 #include "test_allocator.h"
29
30 template <class T>
31 struct some_alloc
32 {
33 typedef T value_type;
34
some_allocsome_alloc35 some_alloc() {}
36 some_alloc(const some_alloc&);
37 T *allocate(size_t);
deallocatesome_alloc38 void deallocate(void*, unsigned) {}
39 typedef std::true_type propagate_on_container_swap;
40 };
41
42 template <class T>
43 struct some_alloc2
44 {
45 typedef T value_type;
46
some_alloc2some_alloc247 some_alloc2() {}
48 some_alloc2(const some_alloc2&);
49 T *allocate(size_t);
deallocatesome_alloc250 void deallocate(void*, unsigned) {}
51
52 typedef std::false_type propagate_on_container_swap;
53 typedef std::true_type is_always_equal;
54 };
55
main(int,char **)56 int main(int, char**)
57 {
58 {
59 typedef std::string C;
60 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
61 }
62 #if defined(_LIBCPP_VERSION)
63 {
64 typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;
65 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
66 }
67 #endif // _LIBCPP_VERSION
68 {
69 typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
70 #if TEST_STD_VER >= 14
71 // In C++14, if POCS is set, swapping the allocator is required not to throw
72 static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
73 #else
74 static_assert(!noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
75 #endif
76 }
77 #if TEST_STD_VER >= 14
78 {
79 typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
80 // if the allocators are always equal, then the swap can be noexcept
81 static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
82 }
83 #endif
84
85 return 0;
86 }
87