libstdc++-v3/testsuite/25_algorithms/copy_backward/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
  28   std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
  29   const auto out7 = std::copy_backward(ca0.begin(), ca0.begin() + 8,
  30                                        ma0.begin() + 10);
  31
  32   return out7 == ma0.begin() + 2 && ma0[3] == 1;
  33 }
  34
  35 static_assert(test());
  36
  37 constexpr bool
  38 test02()
  39 {
  40   struct X
  41   {
  42     X() = default;
  43     X& operator=(const X&) = default;
  44     constexpr X& operator=(X&& x) { i = x.i; x.i = 0; return *this; }
  45     int i = 1;
  46   };
  47
  48   X from[1], to[1];
  49   std::copy_backward(std::begin(from), std::end(from), std::end(to));
  50   return from[0].i == 1;
  51 }
  52
  53 static_assert(test02());
  54
  55 constexpr bool
  56 test03()
  57 {
  58   std::array<int, 12> ma0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
  59   const auto out7 = std::copy_backward(ma0.begin(), ma0.begin() + 8,
  60                                        ma0.begin() + 10);
  61
  62   return out7 == ma0.begin() + 2 && *out7 == 0 && *(ma0.begin() + 9) == 7;
  63 }
  64
  65 static_assert(test03());