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

   1 // { dg-options "-std=gnu++17" }
   2 // { dg-do compile { target c++17 } }
   3
   4 // Copyright (C) 2017 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 <utility>
  22
  23 template<typename T, typename U> struct require_same;
  24 template<typename T> struct require_same<T, T> { using type = void; };
  25
  26 template<typename T, typename U>
  27   typename require_same<T, U>::type
  28   check_type(U&) { }
  29
  30 struct MoveOnly
  31 {
  32   MoveOnly() = default;
  33   MoveOnly(MoveOnly&&) {}
  34   MoveOnly& operator=(MoveOnly&&) {}
  35 };
  36
  37 void
  38 test01()
  39 {
  40   std::pair x{5, 6u};
  41   check_type<std::pair<int, unsigned>>(x);
  42   int y = 42;
  43   std::pair x2{y, 48u};
  44   check_type<std::pair<int, unsigned>>(x2);
  45   const int z = 666;
  46   std::pair x3{z, y};
  47   check_type<std::pair<int, int>>(x3);
  48   std::pair x4{1, x};
  49   check_type<std::pair<int, std::pair<int, unsigned>>>(x4);
  50   std::pair mo{MoveOnly(), 2l};
  51   check_type<std::pair<MoveOnly, long>>(mo);
  52   mo = {MoveOnly(), 3l};
  53
  54   std::pair copy = x;
  55   check_type<decltype(x)>(copy);
  56   std::pair copy2{x};
  57   check_type<decltype(x)>(copy2);
  58   std::pair move = std::move(mo);
  59   check_type<decltype(mo)>(move);
  60 }