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-options "-std=gnu++2a" }
  19 // { dg-do compile { target c++2a } }
  20
  21 // P0357R3 reference_wrapper for incomplete types
  22
  23 #include <functional>
  24
  25 struct Incomplete;
  26
  27 template class std::reference_wrapper<Incomplete>;
  28
  29 Incomplete& f();
  30
  31 std::reference_wrapper<Incomplete> r = f();
  32 static_assert( std::is_same_v<decltype(r)::type, Incomplete> );
  33 static_assert( std::is_same_v<decltype(r.get()), Incomplete&> );
  34
  35 std::reference_wrapper r2 = f();
  36 static_assert( std::is_same_v<decltype(r), decltype(r2)> );