libstdc++-v3/testsuite/25_algorithms/merge/constexpr.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 <algorithm>
  21 #include <array>
  22
  23 constexpr bool
  24 test()
  25 {
  26   constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
  27   constexpr std::array<int, 12> cas{{3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14}};
  28   constexpr std::array<int, 3> camm{{-6, -5, -4}};
  29   std::array<int, 24> out0{{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}};
  30
  31   const auto outdd = std::merge(ca0.begin(), ca0.end(),
  32                                 cas.begin(), cas.end(), out0.begin());
  33   if (outdd != out0.end())
  34     return false;
  35
  36   const auto outee = std::merge(ca0.begin(), ca0.end(),
  37                                 camm.begin(), camm.end(), out0.begin(),
  38                                 [](int i, int j){ return i < j; });
  39
  40   return outee == (out0.begin() + ca0.size() + camm.size());
  41 }
  42
  43 static_assert(test());