libstdc++-v3/testsuite/23_containers/unordered_set/hash_policy/71181.cc

// Copyright (C) 2016-2021 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 run { target c++11 } }

#include <unordered_set>

#include <testsuite_hooks.h>

template<typename _USet>
  void
  test(_USet& us, int threshold)
  {
    auto nb_reserved = us.bucket_count();
    us.reserve(nb_reserved);
    auto bkts = us.bucket_count();
    for (int nb_insert = 1; nb_insert <= threshold; ++nb_insert)
      {
	if (nb_insert > nb_reserved)
	  {
	    nb_reserved = bkts;
	    us.reserve(nb_reserved);
	    bkts = us.bucket_count();
	  }

	us.insert(nb_insert);

	VERIFY( us.bucket_count() == bkts );
      }
  }

template<typename _Value>
  using unordered_set_power2_rehash =
  std::_Hashtable<_Value, _Value, std::allocator<_Value>,
		  std::__detail::_Identity,
		  std::equal_to<_Value>,
		  std::hash<_Value>,
		  std::__detail::_Mask_range_hashing,
		  std::__detail::_Default_ranged_hash,
		  std::__detail::_Power2_rehash_policy,
		  std::__detail::_Hashtable_traits<false, true, true>>;

template<typename _USet>
  void
  test_cont()
  {
    _USet us;
    test(us, 150);

    us.clear();
    us.rehash(0);

    test(us, 150);
  }

int main()
{
  test_cont<std::unordered_set<int>>();
  test_cont<unordered_set_power2_rehash<int>>();
  return 0;
}