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 // <string>
11
12 // void swap(basic_string& c)
13 // noexcept(!allocator_type::propagate_on_container_swap::value ||
14 // __is_nothrow_swappable<allocator_type>::value);
15 //
16 // In C++17, the standard says that swap shall have:
17 // noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
18 // allocator_traits<Allocator>::is_always_equal::value);
19
20 // This tests a conforming extension
21
22 #include <string>
23 #include <cassert>
24
25 #include "test_allocator.h"
26
27 template <class T>
28 struct some_alloc
29 {
30 typedef T value_type;
31
some_allocsome_alloc32 some_alloc() {}
33 some_alloc(const some_alloc&);
deallocatesome_alloc34 void deallocate(void*, unsigned) {}
35
36 typedef std::true_type propagate_on_container_swap;
37 };
38
39 template <class T>
40 struct some_alloc2
41 {
42 typedef T value_type;
43
some_alloc2some_alloc244 some_alloc2() {}
45 some_alloc2(const some_alloc2&);
deallocatesome_alloc246 void deallocate(void*, unsigned) {}
47
48 typedef std::false_type propagate_on_container_swap;
49 typedef std::true_type is_always_equal;
50 };
51
main()52 int main()
53 {
54 #if __has_feature(cxx_noexcept)
55 {
56 typedef std::string C;
57 C c1, c2;
58 static_assert(noexcept(swap(c1, c2)), "");
59 }
60 {
61 typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;
62 C c1, c2;
63 static_assert(noexcept(swap(c1, c2)), "");
64 }
65 {
66 typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
67 C c1, c2;
68 #if TEST_STD_VER >= 14
69 // In c++14, if POCS is set, swapping the allocator is required not to throw
70 static_assert( noexcept(swap(c1, c2)), "");
71 #else
72 static_assert(!noexcept(swap(c1, c2)), "");
73 #endif
74 }
75 #if TEST_STD_VER >= 14
76 {
77 typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
78 C c1, c2;
79 // if the allocators are always equal, then the swap can be noexcept
80 static_assert( noexcept(swap(c1, c2)), "");
81 }
82 #endif
83
84 #endif
85 }
86