libstdc++-v3/testsuite/23_containers/array/requirements/constexpr_iter.cc

   1 // { dg-do compile { target c++17 } }
   2 // { dg-add-options no_pch }
   3
   4 // Copyright (C) 2019-2025 Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11 //
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING3.  If not see
  19 // <http://www.gnu.org/licenses/>.
  20
  21 #include <array>
  22
  23 #ifndef __cpp_lib_array_constexpr
  24 # error "Feature test macro for array constexpr is missing in <array>"
  25 #elif __cpp_lib_array_constexpr < 201803L
  26 # error "Feature test macro for array constexpr has wrong value in <array>"
  27 #endif
  28
  29 // This test is compiled as C++17 because array::iterator is just a pointer,
  30 // so always meets the C++20 constexpr iterator requirements, even in C++17.
  31
  32 constexpr int
  33 test()
  34 {
  35   constexpr std::array<int, 3> a1{{1, 2, 3}};
  36   static_assert(1 == *a1.begin());
  37   auto n = a1[0] * a1[1]* a1[2];
  38   static_assert(1 == *a1.cbegin());
  39
  40   std::array<int, 3> a2{{0, 0, 0}};
  41   auto a1i = a1.begin();
  42   auto a1e = a1.end();
  43   auto a2i = a2.begin();
  44   while (a1i != a1e)
  45     *a2i++ = *a1i++;
  46
  47   return n;
  48 }
  49
  50 void
  51 run_test()
  52 {
  53   constexpr int n = test();
  54 }