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 // basic_string& operator=(basic_string&& c)
14 //     noexcept(
15 //         allocator_traits<allocator_type>::propagate_on_container_move_assignment::value ||
16 //         allocator_traits<allocator_type>::is_always_equal::value); // C++17
17 //
18 //  before C++17, we use the conforming extension
19 //     noexcept(
20 //         allocator_type::propagate_on_container_move_assignment::value &&
21 //         is_nothrow_move_assignable<allocator_type>::value);
22 
23 #include <string>
24 #include <cassert>
25 
26 #include "test_macros.h"
27 #include "test_allocator.h"
28 
29 template <class T>
30 struct some_alloc
31 {
32     typedef T value_type;
33     some_alloc(const some_alloc&);
34     T *allocate(size_t);
35 };
36 
37 template <class T>
38 struct some_alloc2
39 {
40     typedef T value_type;
41 
42     some_alloc2() {}
43     some_alloc2(const some_alloc2&);
44     T *allocate(size_t);
45     void deallocate(void*, unsigned) {}
46 
47     typedef std::false_type propagate_on_container_move_assignment;
48     typedef std::true_type is_always_equal;
49 };
50 
51 template <class T>
52 struct some_alloc3
53 {
54     typedef T value_type;
55 
56     some_alloc3() {}
57     some_alloc3(const some_alloc3&);
58     T *allocate(size_t);
59     void deallocate(void*, unsigned) {}
60 
61     typedef std::false_type propagate_on_container_move_assignment;
62     typedef std::false_type is_always_equal;
63 };
64 
65 int main(int, char**)
66 {
67     {
68         typedef std::string C;
69         static_assert(std::is_nothrow_move_assignable<C>::value, "");
70     }
71     {
72         typedef std::basic_string<char, std::char_traits<char>, test_allocator<char>> C;
73         static_assert(!std::is_nothrow_move_assignable<C>::value, "");
74     }
75     {
76         typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
77 #if TEST_STD_VER > 14
78     //  if the allocators are always equal, then the move assignment can be noexcept
79         static_assert( std::is_nothrow_move_assignable<C>::value, "");
80 #else
81         static_assert(!std::is_nothrow_move_assignable<C>::value, "");
82 #endif
83     }
84 #if TEST_STD_VER > 14
85     {
86     //  POCMA is false, always equal
87         typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
88         static_assert( std::is_nothrow_move_assignable<C>::value, "");
89     }
90     {
91     //  POCMA is false, not always equal
92         typedef std::basic_string<char, std::char_traits<char>, some_alloc3<char>> C;
93         static_assert(!std::is_nothrow_move_assignable<C>::value, "");
94     }
95 #endif
96 
97   return 0;
98 }
99