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

   1 // Copyright (C) 2019-2023 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 // P0357R3 reference_wrapper for incomplete types
  21
  22 #include <functional>
  23
  24 struct Incomplete;
  25
  26 template class std::reference_wrapper<Incomplete>;
  27
  28 Incomplete& f();
  29
  30 std::reference_wrapper<Incomplete> r = f();
  31 static_assert( std::is_same_v<decltype(r)::type, Incomplete> );
  32 static_assert( std::is_same_v<decltype(r.get()), Incomplete&> );
  33
  34 std::reference_wrapper r2 = f();
  35 static_assert( std::is_same_v<decltype(r), decltype(r2)> );