//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03, c++11

// <set>

// class multiset

// template<typename K>
//     pair<iterator,iterator>             equal_range(const K& x);        //
//     C++14
// template<typename K>
//     pair<const_iterator,const_iterator> equal_range(const K& x) const;  //
//     C++14

#include <cassert>
#include <set>
#include <utility>

struct Comp {
  using is_transparent = void;

  bool operator()(const std::pair<int, int> &lhs,
                  const std::pair<int, int> &rhs) const {
    return lhs < rhs;
  }

  bool operator()(const std::pair<int, int> &lhs, int rhs) const {
    return lhs.first < rhs;
  }

  bool operator()(int lhs, const std::pair<int, int> &rhs) const {
    return lhs < rhs.first;
  }
};

int main(int, char**) {
  std::multiset<std::pair<int, int>, Comp> s{{2, 1}, {1, 1}, {1, 1}, {1, 1}, {2, 2}};

  auto er = s.equal_range(1);
  long nels = 0;

  for (auto it = er.first; it != er.second; it++) {
    assert(it->first == 1);
    nels++;
  }

  assert(nels == 3);

  return 0;
}