1 //===----------------------------------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 // UNSUPPORTED: c++98, c++03
11
12 // <string>
13
14 // void swap(basic_string& c)
15 // noexcept(!allocator_type::propagate_on_container_swap::value ||
16 // __is_nothrow_swappable<allocator_type>::value);
17 //
18 // In C++17, the standard says that swap shall have:
19 // noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
20 // allocator_traits<Allocator>::is_always_equal::value);
21
22 // This tests a conforming extension
23
24 #include <string>
25 #include <utility>
26 #include <cassert>
27
28 #include "test_macros.h"
29 #include "test_allocator.h"
30
31 template <class T>
32 struct some_alloc
33 {
34 typedef T value_type;
35
some_allocsome_alloc36 some_alloc() {}
37 some_alloc(const some_alloc&);
38 T *allocate(size_t);
deallocatesome_alloc39 void deallocate(void*, unsigned) {}
40 typedef std::true_type propagate_on_container_swap;
41 };
42
43 template <class T>
44 struct some_alloc2
45 {
46 typedef T value_type;
47
some_alloc2some_alloc248 some_alloc2() {}
49 some_alloc2(const some_alloc2&);
50 T *allocate(size_t);
deallocatesome_alloc251 void deallocate(void*, unsigned) {}
52
53 typedef std::false_type propagate_on_container_swap;
54 typedef std::true_type is_always_equal;
55 };
56
main()57 int main()
58 {
59 {
60 typedef std::string C;
61 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
62 }
63 #if defined(_LIBCPP_VERSION)
64 {
65 typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;
66 static_assert(noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
67 }
68 #endif // _LIBCPP_VERSION
69 {
70 typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
71 #if TEST_STD_VER >= 14
72 // In C++14, if POCS is set, swapping the allocator is required not to throw
73 static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
74 #else
75 static_assert(!noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
76 #endif
77 }
78 #if TEST_STD_VER >= 14
79 {
80 typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
81 // if the allocators are always equal, then the swap can be noexcept
82 static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
83 }
84 #endif
85 }
86