libstdc++-v3/testsuite/20_util/pair/cons/deduction.cc

   1 // { dg-do compile { target c++17 } }
   2
   3 // Copyright (C) 2017-2024 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20 #include <utility>
  21
  22 template<typename T, typename U> struct require_same;
  23 template<typename T> struct require_same<T, T> { using type = void; };
  24
  25 template<typename T, typename U>
  26   typename require_same<T, U>::type
  27   check_type(U&) { }
  28
  29 struct MoveOnly
  30 {
  31   MoveOnly() = default;
  32   MoveOnly(MoveOnly&&);
  33   MoveOnly& operator=(MoveOnly&&);
  34 };
  35
  36 void
  37 test01()
  38 {
  39   std::pair x{5, 6u};
  40   check_type<std::pair<int, unsigned>>(x);
  41   int y = 42;
  42   std::pair x2{y, 48u};
  43   check_type<std::pair<int, unsigned>>(x2);
  44   const int z = 666;
  45   std::pair x3{z, y};
  46   check_type<std::pair<int, int>>(x3);
  47   std::pair x4{1, x};
  48   check_type<std::pair<int, std::pair<int, unsigned>>>(x4);
  49   std::pair mo{MoveOnly(), 2l};
  50   check_type<std::pair<MoveOnly, long>>(mo);
  51   mo = {MoveOnly(), 3l};
  52
  53   std::pair copy = x;
  54   check_type<decltype(x)>(copy);
  55   std::pair copy2{x};
  56   check_type<decltype(x)>(copy2);
  57   std::pair move = std::move(mo);
  58   check_type<decltype(mo)>(move);
  59 }