xref: /llvm-project/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp (revision 9ed20568e7de53dce85f1631d7d8c1415e7930ae)
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 // <string>
10 // UNSUPPORTED: c++03, c++11, c++14
11 
12 // template<class InputIterator,
13 //      class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
14 //  basic_string(InputIterator, InputIterator, Allocator = Allocator())
15 //    -> basic_string<typename iterator_traits<InputIterator>::value_type,
16 //                 char_traits<typename iterator_traits<InputIterator>::value_type>,
17 //                 Allocator>; // constexpr since C++20
18 //
19 //  The deduction guide shall not participate in overload resolution if InputIterator
20 //  is a type that does not qualify as an input iterator, or if Allocator is a type
21 //  that does not qualify as an allocator.
22 
23 #include <cassert>
24 #include <cstddef>
25 #include <iterator>
26 #include <string>
27 #include <type_traits>
28 
29 #include "test_macros.h"
30 #include "test_allocator.h"
31 #include "min_allocator.h"
32 #include "asan_testing.h"
33 
34 class NotAnIterator {};
35 using NotAnInputIterator = std::back_insert_iterator<std::basic_string<char16_t>>;
36 
37 template <typename T>
38 struct NotAnAllocator {
39   typedef T value_type;
40 };
41 
42 template <class Iter, class Alloc, class = void>
43 struct CanDeduce : std::false_type {};
44 
45 template <class Iter, class Alloc>
46 struct CanDeduce<Iter,
47                  Alloc,
48                  decltype((void)std::basic_string{std::declval<Iter>(), std::declval<Iter>(), std::declval<Alloc>()})>
49     : std::true_type {};
50 
51 static_assert(CanDeduce<char*, std::allocator<char>>::value);
52 static_assert(!CanDeduce<NotAnIterator, std::allocator<char>>::value);
53 static_assert(!CanDeduce<NotAnInputIterator, std::allocator<char16_t>>::value);
54 static_assert(!CanDeduce<char*, NotAnAllocator<char>>::value);
55 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
56 static_assert(CanDeduce<wchar_t*, std::allocator<wchar_t>>::value);
57 static_assert(!CanDeduce<wchar_t const*, NotAnAllocator<wchar_t>>::value);
58 #endif
59 
test()60 TEST_CONSTEXPR_CXX20 bool test() {
61   {
62     const char* s = "12345678901234";
63     std::basic_string s1(s, s + 10); // Can't use {} here
64     using S = decltype(s1);          // what type did we get?
65     static_assert(std::is_same_v<S::value_type, char>, "");
66     static_assert(std::is_same_v<S::traits_type, std::char_traits<char>>, "");
67     static_assert(std::is_same_v<S::allocator_type, std::allocator<char>>, "");
68     assert(s1.size() == 10);
69     assert(s1.compare(0, s1.size(), s, s1.size()) == 0);
70     LIBCPP_ASSERT(is_string_asan_correct(s1));
71   }
72   {
73     const char* s = "12345678901234";
74     std::basic_string s1{s, s + 10, std::allocator<char>{}};
75     using S = decltype(s1); // what type did we get?
76     static_assert(std::is_same_v<S::value_type, char>, "");
77     static_assert(std::is_same_v<S::traits_type, std::char_traits<char>>, "");
78     static_assert(std::is_same_v<S::allocator_type, std::allocator<char>>, "");
79     assert(s1.size() == 10);
80     assert(s1.compare(0, s1.size(), s, s1.size()) == 0);
81     LIBCPP_ASSERT(is_string_asan_correct(s1));
82   }
83 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
84   {
85     const wchar_t* s = L"12345678901234";
86     std::basic_string s1{s, s + 10, test_allocator<wchar_t>{}};
87     using S = decltype(s1); // what type did we get?
88     static_assert(std::is_same_v<S::value_type, wchar_t>, "");
89     static_assert(std::is_same_v<S::traits_type, std::char_traits<wchar_t>>, "");
90     static_assert(std::is_same_v<S::allocator_type, test_allocator<wchar_t>>, "");
91     assert(s1.size() == 10);
92     assert(s1.compare(0, s1.size(), s, s1.size()) == 0);
93     LIBCPP_ASSERT(is_string_asan_correct(s1));
94   }
95 #endif
96   {
97     const char16_t* s = u"12345678901234";
98     std::basic_string s1{s, s + 10, min_allocator<char16_t>{}};
99     using S = decltype(s1); // what type did we get?
100     static_assert(std::is_same_v<S::value_type, char16_t>, "");
101     static_assert(std::is_same_v<S::traits_type, std::char_traits<char16_t>>, "");
102     static_assert(std::is_same_v<S::allocator_type, min_allocator<char16_t>>, "");
103     assert(s1.size() == 10);
104     assert(s1.compare(0, s1.size(), s, s1.size()) == 0);
105     LIBCPP_ASSERT(is_string_asan_correct(s1));
106   }
107   {
108     const char32_t* s = U"12345678901234";
109     std::basic_string s1{s, s + 10, explicit_allocator<char32_t>{}};
110     using S = decltype(s1); // what type did we get?
111     static_assert(std::is_same_v<S::value_type, char32_t>, "");
112     static_assert(std::is_same_v<S::traits_type, std::char_traits<char32_t>>, "");
113     static_assert(std::is_same_v<S::allocator_type, explicit_allocator<char32_t>>, "");
114     assert(s1.size() == 10);
115     assert(s1.compare(0, s1.size(), s, s1.size()) == 0);
116     LIBCPP_ASSERT(is_string_asan_correct(s1));
117   }
118 
119   return true;
120 }
121 
main(int,char **)122 int main(int, char**) {
123   test();
124 #if TEST_STD_VER > 17
125   static_assert(test());
126 #endif
127 
128   return 0;
129 }
130