libstdc++-v3/testsuite/23_containers/span/everything.cc

   1 // Copyright (C) 2019-2025 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do run { target c++20 } }
  19
  20 #include <testsuite_hooks.h>
  21
  22 #include <span>
  23 #include <type_traits>
  24 #include <cstdint>
  25 #include <vector>
  26 #include <algorithm>
  27 #include <cassert>
  28
  29 int
  30 main()
  31 {
  32   struct alignas(256) strawman
  33   {
  34     int x;
  35     int y;
  36     bool z;
  37     int w;
  38   };
  39
  40   struct naked_span
  41   {
  42     char* p;
  43     std::size_t n;
  44   };
  45
  46   struct strawman_span
  47   {
  48     strawman* p;
  49     std::size_t n;
  50   };
  51
  52   static_assert(sizeof(std::span<char, 0>) <= sizeof(char*));
  53   static_assert(sizeof(std::span<const char, 0>) <= sizeof(const char*));
  54   static_assert(sizeof(std::span<strawman, 0>) <= sizeof(strawman*));
  55   static_assert(sizeof(std::span<strawman, 1>) <= sizeof(strawman*));
  56   static_assert(sizeof(std::span<char>) <= sizeof(naked_span));
  57   static_assert(sizeof(std::span<strawman>) <= sizeof(strawman_span));
  58
  59   constexpr static std::array<int, 9> arr_data{ 0, 1, 2, 3, 4, 5, 6, 7, 8 };
  60   constexpr auto arr_data_span = std::span(arr_data);
  61   static_assert(arr_data_span.size() == 9);
  62   static_assert(arr_data_span.size_bytes() == 9 * sizeof(int));
  63   static_assert(*arr_data_span.begin() == 0);
  64   static_assert(*arr_data_span.data() == 0);
  65   static_assert(arr_data_span.front() == 0);
  66   static_assert(arr_data_span.back() == 8);
  67   static_assert(arr_data_span[0] == 0);
  68   static_assert(arr_data_span[1] == 1);
  69   static_assert(arr_data_span[2] == 2);
  70   static_assert(arr_data_span[3] == 3);
  71   static_assert(arr_data_span[4] == 4);
  72   static_assert(arr_data_span[5] == 5);
  73   static_assert(arr_data_span[6] == 6);
  74   static_assert(arr_data_span[7] == 7);
  75   static_assert(arr_data_span[8] == 8);
  76   static_assert(!arr_data_span.empty());
  77   static_assert(decltype(arr_data_span)::extent == 9);
  78
  79   constexpr static int data[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8 };
  80   constexpr auto data_span    = std::span(data);
  81   static_assert(data_span.size() == 9);
  82   static_assert(data_span.size_bytes() == 9 * sizeof(int));
  83   static_assert(*data_span.begin() == 0);
  84   static_assert(*data_span.data() == 0);
  85   static_assert(data_span.front() == 0);
  86   static_assert(data_span.back() == 8);
  87   static_assert(data_span[0] == 0);
  88   static_assert(data_span[1] == 1);
  89   static_assert(data_span[2] == 2);
  90   static_assert(data_span[3] == 3);
  91   static_assert(data_span[4] == 4);
  92   static_assert(data_span[5] == 5);
  93   static_assert(data_span[6] == 6);
  94   static_assert(data_span[7] == 7);
  95   static_assert(data_span[8] == 8);
  96   static_assert(!data_span.empty());
  97   static_assert(decltype(data_span)::extent == 9);
  98
  99   constexpr auto data_span_first = data_span.first<3>();
 100   static_assert(
 101     std::is_same_v<std::remove_cv_t<decltype(data_span_first)>, std::span<const int, 3>>);
 102   static_assert(decltype(data_span_first)::extent == 3);
 103   static_assert(data_span_first.size() == 3);
 104   static_assert(data_span_first.front() == 0);
 105   static_assert(data_span_first.back() == 2);
 106
 107   constexpr auto data_span_first_dyn = data_span.first(4);
 108   static_assert(
 109     std::is_same_v<std::remove_cv_t<decltype(data_span_first_dyn)>, std::span<const int>>);
 110   static_assert(decltype(data_span_first_dyn)::extent == std::dynamic_extent);
 111   static_assert(data_span_first_dyn.size() == 4);
 112   static_assert(data_span_first_dyn.front() == 0);
 113   static_assert(data_span_first_dyn.back() == 3);
 114
 115   constexpr auto data_span_last = data_span.last<5>();
 116   static_assert(
 117     std::is_same_v<std::remove_cv_t<decltype(data_span_last)>, std::span<const int, 5>>);
 118   static_assert(decltype(data_span_last)::extent == 5);
 119   static_assert(data_span_last.size() == 5);
 120   static_assert(data_span_last.front() == 4);
 121   static_assert(data_span_last.back() == 8);
 122
 123   constexpr auto data_span_last_dyn = data_span.last(6);
 124   static_assert(
 125     std::is_same_v<std::remove_cv_t<decltype(data_span_last_dyn)>, std::span<const int>>);
 126   static_assert(decltype(data_span_last_dyn)::extent == std::dynamic_extent);
 127   static_assert(data_span_last_dyn.size() == 6);
 128   static_assert(data_span_last_dyn.front() == 3);
 129   static_assert(data_span_last_dyn.back() == 8);
 130
 131   constexpr auto data_span_subspan = data_span.subspan<1, 3>();
 132   static_assert(
 133     std::is_same_v<std::remove_cv_t<decltype(data_span_subspan)>, std::span<const int, 3>>);
 134   static_assert(decltype(data_span_subspan)::extent == 3);
 135   static_assert(data_span_subspan.size() == 3);
 136   static_assert(data_span_subspan.front() == 1);
 137   static_assert(data_span_subspan.back() == 3);
 138
 139   constexpr auto data_span_subspan_offset = data_span.subspan<8>();
 140   static_assert(
 141     std::is_same_v<std::remove_cv_t<decltype(data_span_subspan_offset)>, std::span<const int, 1>>);
 142   static_assert(decltype(data_span_subspan_offset)::extent == 1);
 143   static_assert(data_span_subspan_offset.size() == 1);
 144   static_assert(data_span_subspan_offset.front() == 8);
 145   static_assert(data_span_subspan_offset.back() == 8);
 146
 147   constexpr auto data_span_subspan_empty = data_span.subspan(9, 0);
 148   static_assert(
 149     std::is_same_v<std::remove_cv_t<decltype(data_span_subspan_empty)>, std::span<const int>>);
 150   static_assert(decltype(data_span_subspan_empty)::extent == std::dynamic_extent);
 151   static_assert(data_span_subspan_empty.size() == 0);
 152
 153   constexpr auto data_span_subspan_empty_static = data_span.subspan<9>();
 154   static_assert(std::is_same_v<std::remove_cv_t<decltype(data_span_subspan_empty_static)>,
 155     std::span<const int, 0>>);
 156   static_assert(decltype(data_span_subspan_empty_static)::extent == 0);
 157   static_assert(data_span_subspan_empty.size() == 0);
 158
 159   std::span<short> shorts{};
 160   bool really_empty0 = shorts.empty();
 161   bool really_empty1 = std::empty(shorts);
 162   bool really_empty2 = shorts.data() == nullptr;
 163   bool really_empty3 = shorts.begin() == shorts.end();
 164   bool really_empty =
 165     really_empty0 && really_empty1 && really_empty2 && really_empty3;
 166   (void)really_empty;
 167   VERIFY(really_empty);
 168
 169   std::vector<std::int_least32_t> value{ 0 };
 170   std::span<int32_t> muh_span(value);
 171   VERIFY(muh_span.size() == 1);
 172   std::byte* original_bytes                  = reinterpret_cast<std::byte*>(value.data());
 173   original_bytes[0]                          = static_cast<std::byte>(1);
 174   original_bytes[1]                          = static_cast<std::byte>(2);
 175   original_bytes[2]                          = static_cast<std::byte>(3);
 176   original_bytes[3]                          = static_cast<std::byte>(4);
 177   std::span<const std::byte> muh_byte_span   = std::as_bytes(muh_span);
 178   std::span<std::byte> muh_mutable_byte_span = std::as_writable_bytes(muh_span);
 179   std::span<std::byte> muh_original_byte_span(original_bytes, original_bytes + 4);
 180   bool definitely_reinterpret_casted0 = std::equal(muh_byte_span.begin(), muh_byte_span.end(),
 181     muh_original_byte_span.begin(), muh_original_byte_span.end());
 182   bool definitely_reinterpret_casted1 = std::equal(muh_mutable_byte_span.begin(),
 183     muh_mutable_byte_span.end(), muh_original_byte_span.begin(), muh_original_byte_span.end());
 184   bool definitely_reinterpret_casted =
 185     definitely_reinterpret_casted0 && definitely_reinterpret_casted1;
 186   (void)definitely_reinterpret_casted;
 187   VERIFY(definitely_reinterpret_casted);
 188
 189   std::span<std::byte> muh_original_byte_span_ptr_size(original_bytes, 4);
 190   bool definitely_equivalent =
 191     std::equal(muh_original_byte_span_ptr_size.begin(), muh_original_byte_span_ptr_size.end(),
 192       muh_original_byte_span.begin(), muh_original_byte_span.end());
 193   (void)definitely_equivalent;
 194   VERIFY(definitely_equivalent);
 195
 196   return definitely_equivalent && definitely_reinterpret_casted && really_empty ? 0 : 1;
 197 }