// { dg-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }

// Copyright (C) 2018-2023 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/>.

#include <unordered_map>
#include <string>
#include <testsuite_hooks.h>

#ifndef __cpp_lib_erase_if
# error "Feature-test macro for erase_if missing in <unordered_map>"
#elif __cpp_lib_erase_if < 202002
# error "Feature-test macro for erase_if has wrong value in <unordered_map>"
#endif

auto is_odd_pair = [](const std::pair<const int, std::string>& p)
{
  return p.first % 2 != 0;
};

void
test01()
{
  std::unordered_map<int, std::string> um{ { 10, "A" }, { 11, "B" },
					   { 12, "C" }, { 14, "D" },
					   { 15, "E" }, { 17, "F" },
					   { 18, "G" }, { 19, "H" } };
  auto num = std::erase_if(um, is_odd_pair);
  std::unordered_map<int, std::string> t{ { 10, "A" }, { 12, "C" },
					  { 14, "D" }, { 18, "G" } };
  VERIFY( um == t );
  VERIFY( num == 4 );
}

void
test02()
{
  std::unordered_multimap<int, std::string> umm{ { 20, "S" }, { 21, "T" },
						 { 22, "U" }, { 22, "V" },
						 { 23, "W" }, { 23, "X" },
						 { 24, "Y" }, { 25, "Z" } };
  auto num = std::erase_if(umm, is_odd_pair);
  std::unordered_multimap<int, std::string> t{ { 20, "S" }, { 22, "U" },
					       { 22, "V" }, { 24, "Y" } };
  VERIFY( umm == t );
  VERIFY( num == 4 );
}

void
test_pr107850()
{
  // Predicate only callable as non-const and only accepts non-const argument.
  struct Pred { bool operator()(std::pair<const int, int>&) { return false; } };
  const Pred pred; // erase_if parameter is passed by value, so non-const.
  std::unordered_map<int, int> m;
  std::erase_if(m, pred);
  std::unordered_multimap<int, int> mm;
  std::erase_if(mm, pred);
}

int
main()
{
  test01();
  test02();
  test_pr107850();

  return 0;
}