libstdc++-v3/testsuite/20_util/reference_wrapper/deduction.cc

   1 // Copyright (C) 2018-2024 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++17 } }
  19
  20 #include <functional>
  21
  22 void
  23 test01()
  24 {
  25   int i = 0;
  26   std::reference_wrapper rw0(i);
  27   [[maybe_unused]] std::reference_wrapper<int>* p0 = &rw0;
  28   [[maybe_unused]] int& r0 = rw0;
  29
  30   std::reference_wrapper rw1(rw0);
  31   [[maybe_unused]] std::reference_wrapper<int>* p1 = &rw1;
  32   [[maybe_unused]] int& r1 = rw1;
  33 }
  34
  35 void
  36 test02()
  37 {
  38   const int i = 0;
  39   std::reference_wrapper rw0(i);
  40   [[maybe_unused]] std::reference_wrapper<const int>* p0 = &rw0;
  41
  42   std::reference_wrapper rw1(rw0);
  43   [[maybe_unused]] std::reference_wrapper<const int>* p1 = &rw1;
  44 }