libstdc++-v3/testsuite/23_containers/span/lwg3255.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 compile { target c++20 } }
  19
  20 #include <span>
  21 #include <array>
  22
  23 using std::span;
  24 using std::dynamic_extent;
  25 using std::array;
  26 using std::is_constructible_v;
  27
  28 // LWG 3255 span's array constructor is too strict
  29
  30 static_assert( is_constructible_v<span<const int* const>, array<int*, 2>> );
  31 static_assert( is_constructible_v<span<const int>, array<const int, 4>> );
  32
  33 static_assert( is_constructible_v<span<int, 1>, int(&)[1]> );
  34 static_assert( is_constructible_v<span<const int, 1>, int(&)[1]> );
  35 static_assert( is_constructible_v<span<const int, 1>, const int(&)[1]> );
  36
  37 static_assert( is_constructible_v<span<int, 1>, array<int, 1>&> );
  38 static_assert( is_constructible_v<span<const int, 1>, array<int, 1>&> );
  39 static_assert( is_constructible_v<span<const int, 1>, array<const int, 1>&> );
  40
  41 static_assert( is_constructible_v<span<const int, 1>, const array<int, 1>&> );
  42 static_assert( is_constructible_v<span<const int, 1>, const array<const int, 1>&> );
  43
  44 static_assert( !is_constructible_v<span<int, 1>, int(&)[2]> );
  45 static_assert( !is_constructible_v<span<const int, 1>, int(&)[2]> );
  46 static_assert( !is_constructible_v<span<const int, 1>, const int(&)[2]> );
  47
  48 static_assert( !is_constructible_v<span<int, 1>, array<int, 2>&> );
  49 static_assert( !is_constructible_v<span<const int, 1>, array<int, 2>&> );
  50 static_assert( !is_constructible_v<span<const int, 1>, array<const int, 2>&> );
  51
  52 static_assert( !is_constructible_v<span<int, 1>, const array<int, 2>&> );
  53 static_assert( !is_constructible_v<span<const int, 1>, const array<int, 2>&> );
  54 static_assert( !is_constructible_v<span<const int, 1>, const array<const int, 2>&> );
  55
  56 static_assert( is_constructible_v<span<int>, int(&)[2]> );
  57 static_assert( is_constructible_v<span<const int>, int(&)[2]> );
  58 static_assert( is_constructible_v<span<const int>, const int(&)[2]> );
  59 static_assert( is_constructible_v<span<const int>, int[2]> );
  60 static_assert( is_constructible_v<span<const int>, const int[2]> );
  61
  62 static_assert( is_constructible_v<span<int>, array<int, 2>&> );
  63 static_assert( is_constructible_v<span<const int>, array<int, 2>&> );
  64 static_assert( is_constructible_v<span<const int>, array<const int, 2>&> );
  65 static_assert( is_constructible_v<span<const int>, array<int, 2>> );
  66 static_assert( is_constructible_v<span<const int>, array<const int, 2>> );
  67
  68 static_assert( is_constructible_v<span<const int>, const array<int, 2>&> );
  69 static_assert( is_constructible_v<span<const int>, const array<const int, 2>&> );
  70
  71 static_assert( ! is_constructible_v<span<int, 1>, array<const int, 1>&> );
  72 static_assert( ! is_constructible_v<span<int, 1>, const array<int, 1>&> );
  73 static_assert( ! is_constructible_v<span<int, 1>, const array<const int, 1>&> );
  74 static_assert( ! is_constructible_v<span<int>, array<const int, 2>&> );
  75 static_assert( ! is_constructible_v<span<int>, const array<int, 2>&> );
  76 static_assert( ! is_constructible_v<span<int>, const array<const int, 2>&> );