libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp

   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
  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
 122 int main(int, char**) {
 123   test();
 124 #if TEST_STD_VER > 17
 125   static_assert(test());
 126 #endif
 127
 128   return 0;
 129 }