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 // basic_string& operator=(basic_string&& c)
13 //     noexcept(
14 //         allocator_traits<allocator_type>::propagate_on_container_move_assignment::value ||
15 //         allocator_traits<allocator_type>::is_always_equal::value); // C++17
16 //
17 //	before C++17, we use the conforming extension
18 //     noexcept(
19 //         allocator_type::propagate_on_container_move_assignment::value &&
20 //         is_nothrow_move_assignable<allocator_type>::value);
21 
22 #include <string>
23 #include <cassert>
24 
25 #include "test_macros.h"
26 #include "test_allocator.h"
27 
28 template <class T>
29 struct some_alloc
30 {
31     typedef T value_type;
32     some_alloc(const some_alloc&);
33 };
34 
35 template <class T>
36 struct some_alloc2
37 {
38     typedef T value_type;
39 
40     some_alloc2() {}
41     some_alloc2(const some_alloc2&);
42     void deallocate(void*, unsigned) {}
43 
44     typedef std::false_type propagate_on_container_move_assignment;
45     typedef std::true_type is_always_equal;
46 };
47 
48 template <class T>
49 struct some_alloc3
50 {
51     typedef T value_type;
52 
53     some_alloc3() {}
54     some_alloc3(const some_alloc3&);
55     void deallocate(void*, unsigned) {}
56 
57     typedef std::false_type propagate_on_container_move_assignment;
58     typedef std::false_type is_always_equal;
59 };
60 
61 int main()
62 {
63 #if __has_feature(cxx_noexcept)
64     {
65         typedef std::string C;
66         static_assert(std::is_nothrow_move_assignable<C>::value, "");
67     }
68     {
69         typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;
70         static_assert(!std::is_nothrow_move_assignable<C>::value, "");
71     }
72     {
73         typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
74 #if TEST_STD_VER > 14
75     //  if the allocators are always equal, then the move assignment can be noexcept
76         static_assert( std::is_nothrow_move_assignable<C>::value, "");
77 #else
78         static_assert(!std::is_nothrow_move_assignable<C>::value, "");
79 #endif
80     }
81 #if TEST_STD_VER > 14
82     {
83     //	POCMA is false, always equal
84         typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
85         static_assert( std::is_nothrow_move_assignable<C>::value, "");
86     }
87     {
88     //	POCMA is false, not always equal
89         typedef std::basic_string<char, std::char_traits<char>, some_alloc3<char>> C;
90         static_assert(!std::is_nothrow_move_assignable<C>::value, "");
91     }
92 #endif
93 
94 #endif
95 }
96