gcc/libstdc++-v3/testsuite/23_containers/set/85965.cc

// Copyright (C) 2019-2022 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

// { dg-do compile { target c++11 } }

#include <set>

struct Base { };
struct Derived; // derives from Base, but incomplete at this point

struct Foo
{
  // PR libstdc++/85965
  std::set<Derived*, std::less<Base*>> s;
};

std::size_t
test01(std::set<Derived*, std::less<Base*>> s)
{
  // these operations should not require the comparison object
  auto copy = s;
  copy = s;
  return s.size();
}