[thirdparty/gcc.git] / libstdc++-v3 / include / debug / unordered_map

// Debugging unordered_map/unordered_multimap implementation -*- C++ -*-

// Copyright (C) 2003-2025 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.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file debug/unordered_map
 *  This file is a GNU debug extension to the Standard C++ Library.
 */

#ifndef _GLIBCXX_DEBUG_UNORDERED_MAP
#define _GLIBCXX_DEBUG_UNORDERED_MAP 1

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
# include <bits/c++config.h>
namespace std _GLIBCXX_VISIBILITY(default) { namespace __debug {
  template<typename _Key, typename _Tp, typename _Hash, typename _Pred,
           typename _Allocator>
    class unordered_map;
  template<typename _Key, typename _Tp, typename _Hash, typename _Pred,
           typename _Allocator>
    class unordered_multimap;
} } // namespace std::__debug

# include <unordered_map>

#include <debug/safe_unordered_container.h>
#include <debug/safe_container.h>
#include <debug/safe_iterator.h>
#include <debug/safe_local_iterator.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
namespace __debug
{
  /// Class std::unordered_map with safety/checking/debug instrumentation.
  template<typename _Key, typename _Tp,
           typename _Hash = std::hash<_Key>,
           typename _Pred = std::equal_to<_Key>,
           typename _Alloc = std::allocator<std::pair<const _Key, _Tp> > >
    class unordered_map
    : public __gnu_debug::_Safe_container<
        unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>, _Alloc,
        __gnu_debug::_Safe_unordered_container>,
      public _GLIBCXX_STD_C::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>
    {
      typedef _GLIBCXX_STD_C::unordered_map<_Key, _Tp, _Hash,
                                            _Pred, _Alloc>              _Base;
      typedef __gnu_debug::_Safe_container<unordered_map,
                   _Alloc, __gnu_debug::_Safe_unordered_container>      _Safe;
      typedef typename _Base::const_iterator    _Base_const_iterator;
      typedef typename _Base::iterator          _Base_iterator;
      typedef typename _Base::const_local_iterator
                                                _Base_const_local_iterator;
      typedef typename _Base::local_iterator    _Base_local_iterator;

      template<typename _ItT, typename _SeqT, typename _CatT>
        friend class ::__gnu_debug::_Safe_iterator;
      template<typename _ItT, typename _SeqT>
        friend class ::__gnu_debug::_Safe_local_iterator;

      // Reference wrapper for base class. See PR libstdc++/90102.
      struct _Base_ref
      {
        _Base_ref(const _Base& __r) : _M_ref(__r) { }

        const _Base& _M_ref;
      };

    public:
      typedef typename _Base::size_type                 size_type;
      typedef typename _Base::hasher                    hasher;
      typedef typename _Base::key_equal                 key_equal;
      typedef typename _Base::allocator_type            allocator_type;

      typedef typename _Base::key_type                  key_type;
      typedef typename _Base::value_type                value_type;
      typedef typename _Base::mapped_type               mapped_type;

      typedef typename _Base::pointer                   pointer;
      typedef typename _Base::const_pointer             const_pointer;
      typedef typename _Base::reference                 reference;
      typedef typename _Base::const_reference           const_reference;
      typedef __gnu_debug::_Safe_iterator<
        _Base_iterator, unordered_map>                  iterator;
      typedef __gnu_debug::_Safe_iterator<
        _Base_const_iterator, unordered_map>            const_iterator;
      typedef __gnu_debug::_Safe_local_iterator<
        _Base_local_iterator, unordered_map>            local_iterator;
      typedef __gnu_debug::_Safe_local_iterator<
        _Base_const_local_iterator, unordered_map>      const_local_iterator;
      typedef typename _Base::difference_type           difference_type;

      unordered_map() = default;

      explicit
      unordered_map(size_type __n,
                    const hasher& __hf = hasher(),
                    const key_equal& __eql = key_equal(),
                    const allocator_type& __a = allocator_type())
      : _Base(__n, __hf, __eql, __a) { }

      template<typename _InputIterator>
        unordered_map(_InputIterator __first, _InputIterator __last,
                      size_type __n = 0,
                      const hasher& __hf = hasher(),
                      const key_equal& __eql = key_equal(),
                      const allocator_type& __a = allocator_type())
        : _Base(__gnu_debug::__base(
                  __glibcxx_check_valid_constructor_range(__first, __last)),
                __gnu_debug::__base(__last), __n,
                __hf, __eql, __a) { }

      unordered_map(const unordered_map&) = default;

      unordered_map(_Base_ref __x)
      : _Base(__x._M_ref) { }

      unordered_map(unordered_map&&) = default;

      explicit
      unordered_map(const allocator_type& __a)
      : _Base(__a) { }

      unordered_map(const unordered_map& __umap,
                    const allocator_type& __a)
      : _Base(__umap, __a) { }

      unordered_map(unordered_map&& __umap,
                    const allocator_type& __a)
      noexcept( noexcept(_Base(std::move(__umap), __a)) )
      : _Safe(std::move(__umap), __a),
        _Base(std::move(__umap), __a) { }

      unordered_map(initializer_list<value_type> __l,
                    size_type __n = 0,
                    const hasher& __hf = hasher(),
                    const key_equal& __eql = key_equal(),
                    const allocator_type& __a = allocator_type())
      : _Base(__l, __n, __hf, __eql, __a) { }

      unordered_map(size_type __n, const allocator_type& __a)
      : unordered_map(__n, hasher(), key_equal(), __a)
      { }

      unordered_map(size_type __n,
                    const hasher& __hf,
                    const allocator_type& __a)
      : unordered_map(__n, __hf, key_equal(), __a)
      { }

      template<typename _InputIterator>
        unordered_map(_InputIterator __first, _InputIterator __last,
                      const allocator_type& __a)
        : unordered_map(__first, __last, 0, hasher(), key_equal(), __a)
        { }

      template<typename _InputIterator>
        unordered_map(_InputIterator __first, _InputIterator __last,
                      size_type __n,
                      const allocator_type& __a)
        : unordered_map(__first, __last, __n, hasher(), key_equal(), __a)
        { }

      template<typename _InputIterator>
        unordered_map(_InputIterator __first, _InputIterator __last,
                      size_type __n,
                      const hasher& __hf,
                      const allocator_type& __a)
        : unordered_map(__first, __last, __n, __hf, key_equal(), __a)
        { }

      unordered_map(initializer_list<value_type> __l,
                    const allocator_type& __a)
      : unordered_map(__l, 0, hasher(), key_equal(), __a)
      { }

      unordered_map(initializer_list<value_type> __l,
                    size_type __n,
                    const allocator_type& __a)
      : unordered_map(__l, __n, hasher(), key_equal(), __a)
      { }

      unordered_map(initializer_list<value_type> __l,
                    size_type __n,
                    const hasher& __hf,
                    const allocator_type& __a)
      : unordered_map(__l, __n, __hf, key_equal(), __a)
      { }

#if __glibcxx_containers_ranges // C++ >= 23
      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_map(from_range_t, _Rg&& __rg,
                      size_type __n = 0,
                      const hasher& __hf = hasher(),
                      const key_equal& __eql = key_equal(),
                      const allocator_type& __a = allocator_type())
        : _Base(from_range, std::forward<_Rg>(__rg), __n, __hf, __eql, __a)
        { }

      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_map(from_range_t, _Rg&& __rg, const allocator_type& __a)
        : _Base(from_range, std::forward<_Rg>(__rg), __a)
        { }

      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_map(from_range_t, _Rg&& __rg, size_type __n,
                      const allocator_type& __a)
        : _Base(from_range, std::forward<_Rg>(__rg), __n, __a)
        { }

      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_map(from_range_t, _Rg&& __rg, size_type __n,
                      const hasher& __hf, const allocator_type& __a)
        : _Base(from_range, std::forward<_Rg>(__rg), __n, __hf, __a)
        { }
#endif

      ~unordered_map() = default;

      unordered_map&
      operator=(const unordered_map&) = default;

      unordered_map&
      operator=(unordered_map&&) = default;

      unordered_map&
      operator=(initializer_list<value_type> __l)
      {
        _Base::operator=(__l);
        this->_M_invalidate_all();
        return *this;
      }

      using _Base::get_allocator;
      using _Base::empty;
      using _Base::size;
      using _Base::max_size;

      void
      swap(unordered_map& __x)
        noexcept( noexcept(declval<_Base&>().swap(__x)) )
      {
        _Safe::_M_swap(__x);
        _Base::swap(__x);
      }

      void
      clear() noexcept
      {
        _Base::clear();
        this->_M_invalidate_all();
      }

      iterator
      begin() noexcept
      { return { _Base::begin(), this }; }

      const_iterator
      begin() const noexcept
      { return { _Base::begin(), this }; }

      iterator
      end() noexcept
      { return { _Base::end(), this }; }

      const_iterator
      end() const noexcept
      { return { _Base::end(), this }; }

      const_iterator
      cbegin() const noexcept
      { return { _Base::cbegin(), this }; }

      const_iterator
      cend() const noexcept
      { return { _Base::cend(), this }; }

      // local versions
      local_iterator
      begin(size_type __b)
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::begin(__b), this };
      }

      local_iterator
      end(size_type __b)
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::end(__b), this };
      }

      const_local_iterator
      begin(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::begin(__b), this };
      }

      const_local_iterator
      end(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::end(__b), this };
      }

      const_local_iterator
      cbegin(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::cbegin(__b), this };
      }

      const_local_iterator
      cend(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::cend(__b), this };
      }

      using _Base::bucket_count;
      using _Base::max_bucket_count;
      using _Base::bucket;

      size_type
      bucket_size(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return _Base::bucket_size(__b);
      }

      using _Base::load_factor;

      float
      max_load_factor() const noexcept
      { return _Base::max_load_factor(); }

      void
      max_load_factor(float __f)
      {
        __glibcxx_check_max_load_factor(__f);
        _Base::max_load_factor(__f);
      }

      template<typename... _Args>
        std::pair<iterator, bool>
        emplace(_Args&&... __args)
        {
          size_type __bucket_count = this->bucket_count();
          auto __res = _Base::emplace(std::forward<_Args>(__args)...);
          _M_check_rehashed(__bucket_count);
          return { { __res.first, this }, __res.second };
        }

      template<typename... _Args>
        iterator
        emplace_hint(const_iterator __hint, _Args&&... __args)
        {
          __glibcxx_check_insert(__hint);
          size_type __bucket_count = this->bucket_count();
          auto __it = _Base::emplace_hint(__hint.base(),
                                          std::forward<_Args>(__args)...);
          _M_check_rehashed(__bucket_count);
          return { __it, this };
        }

      std::pair<iterator, bool>
      insert(const value_type& __obj)
      {
        size_type __bucket_count = this->bucket_count();
        auto __res = _Base::insert(__obj);
        _M_check_rehashed(__bucket_count);
        return { { __res.first, this }, __res.second };
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2354. Unnecessary copying when inserting into maps with braced-init
      std::pair<iterator, bool>
      insert(value_type&& __x)
      {
        size_type __bucket_count = this->bucket_count();
        auto __res = _Base::insert(std::move(__x));
        _M_check_rehashed(__bucket_count);
        return { { __res.first, this }, __res.second };
      }

      template<typename _Pair, typename = typename
               std::enable_if<std::is_constructible<value_type,
                                                    _Pair&&>::value>::type>
        std::pair<iterator, bool>
        insert(_Pair&& __obj)
        {
          size_type __bucket_count = this->bucket_count();
          auto __res = _Base::insert(std::forward<_Pair>(__obj));
          _M_check_rehashed(__bucket_count);
          return { { __res.first, this }, __res.second };
        }

      iterator
      insert(const_iterator __hint, const value_type& __obj)
      {
        __glibcxx_check_insert(__hint);
        size_type __bucket_count = this->bucket_count();
        auto __it = _Base::insert(__hint.base(), __obj);
        _M_check_rehashed(__bucket_count);
        return { __it, this };
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2354. Unnecessary copying when inserting into maps with braced-init
      iterator
      insert(const_iterator __hint, value_type&& __x)
      {
        __glibcxx_check_insert(__hint);
        size_type __bucket_count = this->bucket_count();
        auto __it = _Base::insert(__hint.base(), std::move(__x));
        _M_check_rehashed(__bucket_count);
        return { __it, this };
      }

      template<typename _Pair, typename = typename
               std::enable_if<std::is_constructible<value_type,
                                                    _Pair&&>::value>::type>
        iterator
        insert(const_iterator __hint, _Pair&& __obj)
        {
          __glibcxx_check_insert(__hint);
          size_type __bucket_count = this->bucket_count();
          auto __it = _Base::insert(__hint.base(), std::forward<_Pair>(__obj));
          _M_check_rehashed(__bucket_count);
          return { __it, this };
        }

      void
      insert(std::initializer_list<value_type> __l)
      {
        size_type __bucket_count = this->bucket_count();
        _Base::insert(__l);
        _M_check_rehashed(__bucket_count);
      }

      template<typename _InputIterator>
        void
        insert(_InputIterator __first, _InputIterator __last)
        {
          typename __gnu_debug::_Distance_traits<_InputIterator>::__type __dist;
          __glibcxx_check_valid_range2(__first, __last, __dist);
          size_type __bucket_count = this->bucket_count();

          if (__dist.second >= __gnu_debug::__dp_sign)
            _Base::insert(__gnu_debug::__unsafe(__first),
                          __gnu_debug::__unsafe(__last));
          else
            _Base::insert(__first, __last);

          _M_check_rehashed(__bucket_count);
        }

#ifdef __glibcxx_unordered_map_try_emplace // C++ >= 17 && HOSTED
      template <typename... _Args>
        pair<iterator, bool>
        try_emplace(const key_type& __k, _Args&&... __args)
        {
          auto __res = _Base::try_emplace(__k,
                                          std::forward<_Args>(__args)...);
          return { { __res.first, this }, __res.second };
        }

      template <typename... _Args>
        pair<iterator, bool>
        try_emplace(key_type&& __k, _Args&&... __args)
        {
          auto __res = _Base::try_emplace(std::move(__k),
                                          std::forward<_Args>(__args)...);
          return { { __res.first, this }, __res.second };
        }

      template <typename... _Args>
        iterator
        try_emplace(const_iterator __hint, const key_type& __k,
                    _Args&&... __args)
        {
          __glibcxx_check_insert(__hint);
          return { _Base::try_emplace(__hint.base(), __k,
                                      std::forward<_Args>(__args)...),
                   this };
        }

      template <typename... _Args>
        iterator
        try_emplace(const_iterator __hint, key_type&& __k, _Args&&... __args)
        {
          __glibcxx_check_insert(__hint);
          return { _Base::try_emplace(__hint.base(), std::move(__k),
                                      std::forward<_Args>(__args)...),
                   this };
        }

      template <typename _Obj>
        pair<iterator, bool>
        insert_or_assign(const key_type& __k, _Obj&& __obj)
        {
          auto __res = _Base::insert_or_assign(__k,
                                               std::forward<_Obj>(__obj));
          return { { __res.first, this }, __res.second };
        }

      template <typename _Obj>
        pair<iterator, bool>
        insert_or_assign(key_type&& __k, _Obj&& __obj)
        {
          auto __res = _Base::insert_or_assign(std::move(__k),
                                               std::forward<_Obj>(__obj));
          return { { __res.first, this }, __res.second };
        }

      template <typename _Obj>
        iterator
        insert_or_assign(const_iterator __hint, const key_type& __k,
                         _Obj&& __obj)
        {
          __glibcxx_check_insert(__hint);
          return { _Base::insert_or_assign(__hint.base(), __k,
                                           std::forward<_Obj>(__obj)),
                   this };
        }

      template <typename _Obj>
        iterator
        insert_or_assign(const_iterator __hint, key_type&& __k, _Obj&& __obj)
        {
          __glibcxx_check_insert(__hint);
          return { _Base::insert_or_assign(__hint.base(), std::move(__k),
                                           std::forward<_Obj>(__obj)),
                   this };
        }
#endif // C++17

#if __cplusplus > 201402L
      using node_type = typename _Base::node_type;
      using insert_return_type = _Node_insert_return<iterator, node_type>;

      node_type
      extract(const_iterator __position)
      {
        __glibcxx_check_erase(__position);
        return _M_extract(__position.base());
      }

      node_type
      extract(const key_type& __key)
      {
        const auto __position = _Base::find(__key);
        if (__position != _Base::end())
          return _M_extract(__position);
        return {};
      }

      insert_return_type
      insert(node_type&& __nh)
      {
        auto __ret = _Base::insert(std::move(__nh));
        return
          { { __ret.position, this }, __ret.inserted, std::move(__ret.node) };
      }

      iterator
      insert(const_iterator __hint, node_type&& __nh)
      {
        __glibcxx_check_insert(__hint);
        return { _Base::insert(__hint.base(), std::move(__nh)), this };
      }

      template<typename _H2, typename _P2>
        void
        merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>& __source)
        {
          auto __guard
            = _Safe::_S_uc_guard(std::__detail::_Select1st{}, __source);
          _Base::merge(__source);
        }

      template<typename _H2, typename _P2>
        void
        merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
        { merge(__source); }

      template<typename _H2, typename _P2>
        void
        merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>& __source)
        {
          auto __guard
            = _Safe::_S_umc_guard(std::__detail::_Select1st{}, __source);
          _Base::merge(__source);
        }

      template<typename _H2, typename _P2>
        void
        merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
        { merge(__source); }
#endif // C++17

      using _Base::hash_function;
      using _Base::key_eq;

      iterator
      find(const key_type& __key)
      { return { _Base::find(__key), this }; }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        iterator
        find(const _Kt& __k)
        { return { _Base::find(__k), this }; }
#endif

      const_iterator
      find(const key_type& __key) const
      { return { _Base::find(__key), this }; }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        const_iterator
        find(const _Kt& __k) const
        { return { _Base::find(__k), this }; }
#endif

      using _Base::count;
#if __cplusplus > 201703L
      using _Base::contains;
#endif

      std::pair<iterator, iterator>
      equal_range(const key_type& __key)
      {
        auto __res = _Base::equal_range(__key);
        return { { __res.first, this }, { __res.second, this } };
      }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        std::pair<iterator, iterator>
        equal_range(const _Kt& __k)
        {
          auto __res = _Base::equal_range(__k);
          return { { __res.first, this }, { __res.second, this } };
        }
#endif

      std::pair<const_iterator, const_iterator>
      equal_range(const key_type& __key) const
      {
        auto __res = _Base::equal_range(__key);
        return { { __res.first, this }, { __res.second, this } };
      }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        std::pair<const_iterator, const_iterator>
        equal_range(const _Kt& __k) const
        {
          auto __res = _Base::equal_range(__k);
          return { { __res.first, this }, { __res.second, this } };
        }
#endif

      using _Base::operator[];
      using _Base::at;

      size_type
      erase(const key_type& __key)
      {
        size_type __ret(0);
        auto __victim = _Base::find(__key);
        if (__victim != _Base::end())
          {
            _M_erase(__victim);
            __ret = 1;
          }
        return __ret;
      }

      iterator
      erase(const_iterator __it)
      {
        __glibcxx_check_erase(__it);
        return { _M_erase(__it.base()), this };
      }

      _Base_iterator
      erase(_Base_const_iterator __it)
      {
        __glibcxx_check_erase2(__it);
        return _M_erase(__it);
      }

      iterator
      erase(iterator __it)
      {
        __glibcxx_check_erase(__it);
        return { _M_erase(__it.base()), this };
      }

      iterator
      erase(const_iterator __first, const_iterator __last)
      {
        __glibcxx_check_erase_range(__first, __last);
        for (auto __tmp = __first.base(); __tmp != __last.base(); ++__tmp)
          {
            _GLIBCXX_DEBUG_VERIFY(__tmp != _Base::cend(),
                                  _M_message(__gnu_debug::__msg_valid_range)
                                  ._M_iterator(__first, "first")
                                  ._M_iterator(__last, "last"));
            _M_invalidate(__tmp);
          }

        size_type __bucket_count = this->bucket_count();
        auto __next = _Base::erase(__first.base(), __last.base());
        _M_check_rehashed(__bucket_count);
        return { __next, this };
      }

      using _Base::rehash;
      using _Base::reserve;

      _Base&
      _M_base() noexcept        { return *this; }

      const _Base&
      _M_base() const noexcept  { return *this; }

    private:
      void
      _M_check_rehashed(size_type __prev_count)
      {
        if (__prev_count != this->bucket_count())
          this->_M_invalidate_all();
      }

      void
      _M_invalidate(_Base_const_iterator __victim)
      {
        this->_M_invalidate_if(
          [__victim](_Base_const_iterator __it) { return __it == __victim; });
        this->_M_invalidate_local_if(
          [__victim](_Base_const_local_iterator __it)
          { return __it == __victim; });
      }

      _Base_iterator
      _M_erase(_Base_const_iterator __victim)
      {
        _M_invalidate(__victim);
        size_type __bucket_count = this->bucket_count();
        _Base_iterator __next = _Base::erase(__victim);
        _M_check_rehashed(__bucket_count);
        return __next;
      }

#if __cplusplus > 201402L
      node_type
      _M_extract(_Base_const_iterator __victim)
      {
        _M_invalidate(__victim);
        return _Base::extract(__victim);
      }
#endif
    };

#if __cpp_deduction_guides >= 201606

  template<typename _InputIterator,
           typename _Hash = hash<__iter_key_t<_InputIterator>>,
           typename _Pred = equal_to<__iter_key_t<_InputIterator>>,
           typename _Allocator = allocator<__iter_to_alloc_t<_InputIterator>>,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireNotAllocator<_Pred>,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(_InputIterator, _InputIterator,
                  typename unordered_map<int, int>::size_type = {},
                  _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
    -> unordered_map<__iter_key_t<_InputIterator>,
                     __iter_val_t<_InputIterator>,
                     _Hash, _Pred, _Allocator>;

  template<typename _Key, typename _Tp, typename _Hash = hash<_Key>,
           typename _Pred = equal_to<_Key>,
           typename _Allocator = allocator<pair<const _Key, _Tp>>,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireNotAllocator<_Pred>,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(initializer_list<pair<_Key, _Tp>>,
                  typename unordered_map<int, int>::size_type = {},
                  _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
    -> unordered_map<_Key, _Tp, _Hash, _Pred, _Allocator>;

  template<typename _InputIterator, typename _Allocator,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(_InputIterator, _InputIterator,
                  typename unordered_map<int, int>::size_type, _Allocator)
    -> unordered_map<__iter_key_t<_InputIterator>,
                     __iter_val_t<_InputIterator>,
                     hash<__iter_key_t<_InputIterator>>,
                     equal_to<__iter_key_t<_InputIterator>>,
                     _Allocator>;

  template<typename _InputIterator, typename _Allocator,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(_InputIterator, _InputIterator, _Allocator)
    -> unordered_map<__iter_key_t<_InputIterator>,
                     __iter_val_t<_InputIterator>,
                     hash<__iter_key_t<_InputIterator>>,
                     equal_to<__iter_key_t<_InputIterator>>,
                     _Allocator>;

  template<typename _InputIterator, typename _Hash, typename _Allocator,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(_InputIterator, _InputIterator,
                  typename unordered_map<int, int>::size_type,
                  _Hash, _Allocator)
    -> unordered_map<__iter_key_t<_InputIterator>,
                     __iter_val_t<_InputIterator>, _Hash,
                     equal_to<__iter_key_t<_InputIterator>>, _Allocator>;

  template<typename _Key, typename _Tp, typename _Allocator,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(initializer_list<pair<_Key, _Tp>>,
                  typename unordered_map<int, int>::size_type,
                  _Allocator)
    -> unordered_map<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;

  template<typename _Key, typename _Tp, typename _Allocator,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(initializer_list<pair<_Key, _Tp>>, _Allocator)
    -> unordered_map<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;

  template<typename _Key, typename _Tp, typename _Hash, typename _Allocator,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireAllocator<_Allocator>>
    unordered_map(initializer_list<pair<_Key, _Tp>>,
                  typename unordered_map<int, int>::size_type,
                  _Hash, _Allocator)
    -> unordered_map<_Key, _Tp, _Hash, equal_to<_Key>, _Allocator>;

#if __glibcxx_containers_ranges // C++ >= 23
  template<ranges::input_range _Rg,
           __not_allocator_like _Hash = hash<__detail::__range_key_type<_Rg>>,
           __not_allocator_like _Pred = equal_to<__detail::__range_key_type<_Rg>>,
           __allocator_like _Allocator =
             allocator<__detail::__range_to_alloc_type<_Rg>>>
    unordered_map(from_range_t, _Rg&&, unordered_map<int, int>::size_type = {},
                  _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
    -> unordered_map<__detail::__range_key_type<_Rg>,
                     __detail::__range_mapped_type<_Rg>,
                     _Hash, _Pred, _Allocator>;

  template<ranges::input_range _Rg,
           __allocator_like _Allocator>
    unordered_map(from_range_t, _Rg&&, unordered_map<int, int>::size_type,
                  _Allocator)
    -> unordered_map<__detail::__range_key_type<_Rg>,
                     __detail::__range_mapped_type<_Rg>,
                     hash<__detail::__range_key_type<_Rg>>,
                     equal_to<__detail::__range_key_type<_Rg>>,
                     _Allocator>;

  template<ranges::input_range _Rg,
           __allocator_like _Allocator>
    unordered_map(from_range_t, _Rg&&, _Allocator)
    -> unordered_map<__detail::__range_key_type<_Rg>,
                     __detail::__range_mapped_type<_Rg>,
                     hash<__detail::__range_key_type<_Rg>>,
                     equal_to<__detail::__range_key_type<_Rg>>,
                     _Allocator>;

  template<ranges::input_range _Rg,
           __not_allocator_like _Hash,
           __allocator_like _Allocator>
    unordered_map(from_range_t, _Rg&&, unordered_map<int, int>::size_type,
                  _Hash, _Allocator)
    -> unordered_map<__detail::__range_key_type<_Rg>,
                     __detail::__range_mapped_type<_Rg>,
                     _Hash, equal_to<__detail::__range_key_type<_Rg>>,
                     _Allocator>;
#endif
#endif

  template<typename _Key, typename _Tp, typename _Hash,
           typename _Pred, typename _Alloc>
    inline void
    swap(unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
         unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    noexcept(noexcept(__x.swap(__y)))
    { __x.swap(__y); }

  template<typename _Key, typename _Tp, typename _Hash,
           typename _Pred, typename _Alloc>
    inline bool
    operator==(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
               const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    { return __x._M_base() == __y._M_base(); }

#if __cpp_impl_three_way_comparison < 201907L
  template<typename _Key, typename _Tp, typename _Hash,
           typename _Pred, typename _Alloc>
    inline bool
    operator!=(const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
               const unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    { return !(__x == __y); }
#endif

  /// Class std::unordered_multimap with safety/checking/debug instrumentation.
  template<typename _Key, typename _Tp,
           typename _Hash = std::hash<_Key>,
           typename _Pred = std::equal_to<_Key>,
           typename _Alloc = std::allocator<std::pair<const _Key, _Tp> > >
    class unordered_multimap
      : public __gnu_debug::_Safe_container<
        unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>, _Alloc,
        __gnu_debug::_Safe_unordered_container>,
        public _GLIBCXX_STD_C::unordered_multimap<
        _Key, _Tp, _Hash, _Pred, _Alloc>
    {
      typedef _GLIBCXX_STD_C::unordered_multimap<_Key, _Tp, _Hash,
                                                 _Pred, _Alloc>         _Base;
      typedef __gnu_debug::_Safe_container<unordered_multimap,
        _Alloc, __gnu_debug::_Safe_unordered_container>                 _Safe;
      typedef typename _Base::const_iterator       _Base_const_iterator;
      typedef typename _Base::iterator             _Base_iterator;
      typedef typename _Base::const_local_iterator _Base_const_local_iterator;
      typedef typename _Base::local_iterator       _Base_local_iterator;

      template<typename _ItT, typename _SeqT, typename _CatT>
        friend class ::__gnu_debug::_Safe_iterator;
      template<typename _ItT, typename _SeqT>
        friend class ::__gnu_debug::_Safe_local_iterator;

      // Reference wrapper for base class. See PR libstdc++/90102.
      struct _Base_ref
      {
        _Base_ref(const _Base& __r) : _M_ref(__r) { }

        const _Base& _M_ref;
      };

    public:
      typedef typename _Base::size_type                 size_type;
      typedef typename _Base::hasher                    hasher;
      typedef typename _Base::key_equal                 key_equal;
      typedef typename _Base::allocator_type            allocator_type;

      typedef typename _Base::key_type                  key_type;
      typedef typename _Base::value_type                value_type;
      typedef typename _Base::mapped_type               mapped_type;

      typedef typename _Base::pointer                   pointer;
      typedef typename _Base::const_pointer             const_pointer;
      typedef typename _Base::reference                 reference;
      typedef typename _Base::const_reference           const_reference;
      typedef __gnu_debug::_Safe_iterator<
        _Base_iterator, unordered_multimap>             iterator;
      typedef __gnu_debug::_Safe_iterator<
        _Base_const_iterator, unordered_multimap>       const_iterator;
      typedef __gnu_debug::_Safe_local_iterator<
        _Base_local_iterator, unordered_multimap>       local_iterator;
      typedef __gnu_debug::_Safe_local_iterator<
        _Base_const_local_iterator, unordered_multimap> const_local_iterator;
      typedef typename _Base::difference_type           difference_type;

      unordered_multimap() = default;

      explicit
      unordered_multimap(size_type __n,
                         const hasher& __hf = hasher(),
                         const key_equal& __eql = key_equal(),
                         const allocator_type& __a = allocator_type())
      : _Base(__n, __hf, __eql, __a) { }

      template<typename _InputIterator>
        unordered_multimap(_InputIterator __first, _InputIterator __last,
                           size_type __n = 0,
                           const hasher& __hf = hasher(),
                           const key_equal& __eql = key_equal(),
                           const allocator_type& __a = allocator_type())
        : _Base(__gnu_debug::__base(
                  __glibcxx_check_valid_constructor_range(__first, __last)),
                __gnu_debug::__base(__last), __n,
                __hf, __eql, __a) { }

      unordered_multimap(const unordered_multimap&) = default;

      unordered_multimap(_Base_ref __x)
      : _Base(__x._M_ref) { }

      unordered_multimap(unordered_multimap&&) = default;

      explicit
      unordered_multimap(const allocator_type& __a)
      : _Base(__a) { }

      unordered_multimap(const unordered_multimap& __umap,
                         const allocator_type& __a)
      : _Base(__umap, __a) { }

      unordered_multimap(unordered_multimap&& __umap,
                         const allocator_type& __a)
      noexcept( noexcept(_Base(std::move(__umap), __a)) )
      : _Safe(std::move(__umap), __a),
        _Base(std::move(__umap), __a) { }

      unordered_multimap(initializer_list<value_type> __l,
                         size_type __n = 0,
                         const hasher& __hf = hasher(),
                         const key_equal& __eql = key_equal(),
                         const allocator_type& __a = allocator_type())
      : _Base(__l, __n, __hf, __eql, __a) { }

      unordered_multimap(size_type __n, const allocator_type& __a)
      : unordered_multimap(__n, hasher(), key_equal(), __a)
      { }

      unordered_multimap(size_type __n, const hasher& __hf,
                         const allocator_type& __a)
      : unordered_multimap(__n, __hf, key_equal(), __a)
      { }

      template<typename _InputIterator>
        unordered_multimap(_InputIterator __first, _InputIterator __last,
                           const allocator_type& __a)
        : unordered_multimap(__first, __last, 0, hasher(), key_equal(), __a)
        { }

      template<typename _InputIterator>
        unordered_multimap(_InputIterator __first, _InputIterator __last,
                           size_type __n,
                           const allocator_type& __a)
        : unordered_multimap(__first, __last, __n, hasher(), key_equal(), __a)
        { }

      template<typename _InputIterator>
        unordered_multimap(_InputIterator __first, _InputIterator __last,
                           size_type __n, const hasher& __hf,
                           const allocator_type& __a)
        : unordered_multimap(__first, __last, __n, __hf, key_equal(), __a)
        { }

      unordered_multimap(initializer_list<value_type> __l,
                         const allocator_type& __a)
      : unordered_multimap(__l, 0, hasher(), key_equal(), __a)
      { }

      unordered_multimap(initializer_list<value_type> __l,
                         size_type __n,
                         const allocator_type& __a)
      : unordered_multimap(__l, __n, hasher(), key_equal(), __a)
      { }

      unordered_multimap(initializer_list<value_type> __l,
                         size_type __n, const hasher& __hf,
                         const allocator_type& __a)
      : unordered_multimap(__l, __n, __hf, key_equal(), __a)
      { }

#if __glibcxx_containers_ranges // C++ >= 23
      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_multimap(from_range_t, _Rg&& __rg,
                           size_type __n = 0,
                           const hasher& __hf = hasher(),
                           const key_equal& __eql = key_equal(),
                           const allocator_type& __a = allocator_type())
        : _Base(from_range, std::forward<_Rg>(__rg), __n, __hf, __eql, __a)
        { }

      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_multimap(from_range_t, _Rg&& __rg, const allocator_type& __a)
        : _Base(from_range, std::forward<_Rg>(__rg), __a)
        { }

      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_multimap(from_range_t, _Rg&& __rg, size_type __n,
                           const allocator_type& __a)
        : _Base(from_range, std::forward<_Rg>(__rg), __n, __a)
        { }

      template<__detail::__container_compatible_range<value_type> _Rg>
        unordered_multimap(from_range_t, _Rg&& __rg, size_type __n,
                           const hasher& __hf, const allocator_type& __a)
        : _Base(from_range, std::forward<_Rg>(__rg), __n, __hf, __a)
        { }
#endif

      ~unordered_multimap() = default;

      unordered_multimap&
      operator=(const unordered_multimap&) = default;

      unordered_multimap&
      operator=(unordered_multimap&&) = default;

      unordered_multimap&
      operator=(initializer_list<value_type> __l)
      {
        _Base::operator=(__l);
        this->_M_invalidate_all();
        return *this;
      }

      using _Base::get_allocator;
      using _Base::empty;
      using _Base::size;
      using _Base::max_size;

      void
      swap(unordered_multimap& __x)
        noexcept( noexcept(declval<_Base&>().swap(__x)) )
      {
        _Safe::_M_swap(__x);
        _Base::swap(__x);
      }

      void
      clear() noexcept
      {
        _Base::clear();
        this->_M_invalidate_all();
      }

      iterator
      begin() noexcept
      { return { _Base::begin(), this }; }

      const_iterator
      begin() const noexcept
      { return { _Base::begin(), this }; }

      iterator
      end() noexcept
      { return { _Base::end(), this }; }

      const_iterator
      end() const noexcept
      { return { _Base::end(), this }; }

      const_iterator
      cbegin() const noexcept
      { return { _Base::cbegin(), this }; }

      const_iterator
      cend() const noexcept
      { return { _Base::cend(), this }; }

      // local versions
      local_iterator
      begin(size_type __b)
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::begin(__b), this };
      }

      local_iterator
      end(size_type __b)
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::end(__b), this };
      }

      const_local_iterator
      begin(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::begin(__b), this };
      }

      const_local_iterator
      end(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::end(__b), this };
      }

      const_local_iterator
      cbegin(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::cbegin(__b), this };
      }

      const_local_iterator
      cend(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return { _Base::cend(__b), this };
      }

      using _Base::bucket_count;
      using _Base::max_bucket_count;
      using _Base::bucket;

      size_type
      bucket_size(size_type __b) const
      {
        __glibcxx_check_bucket_index(__b);
        return _Base::bucket_size(__b);
      }

      float
      max_load_factor() const noexcept
      { return _Base::max_load_factor(); }

      void
      max_load_factor(float __f)
      {
        __glibcxx_check_max_load_factor(__f);
        _Base::max_load_factor(__f);
      }

      template<typename... _Args>
        iterator
        emplace(_Args&&... __args)
        {
          size_type __bucket_count = this->bucket_count();
          auto __it = _Base::emplace(std::forward<_Args>(__args)...);
          _M_check_rehashed(__bucket_count);
          return { __it, this };
        }

      template<typename... _Args>
        iterator
        emplace_hint(const_iterator __hint, _Args&&... __args)
        {
          __glibcxx_check_insert(__hint);
          size_type __bucket_count = this->bucket_count();
          auto __it = _Base::emplace_hint(__hint.base(),
                                          std::forward<_Args>(__args)...);
          _M_check_rehashed(__bucket_count);
          return { __it, this };
        }

      iterator
      insert(const value_type& __obj)
      {
        size_type __bucket_count = this->bucket_count();
        auto __it = _Base::insert(__obj);
        _M_check_rehashed(__bucket_count);
        return { __it, this };
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2354. Unnecessary copying when inserting into maps with braced-init
      iterator
      insert(value_type&& __x)
      {
        size_type __bucket_count = this->bucket_count();
        auto __it = _Base::insert(std::move(__x));
        _M_check_rehashed(__bucket_count);
        return { __it, this };
      }

      iterator
      insert(const_iterator __hint, const value_type& __obj)
      {
        __glibcxx_check_insert(__hint);
        size_type __bucket_count = this->bucket_count();
        auto __it = _Base::insert(__hint.base(), __obj);
        _M_check_rehashed(__bucket_count);
        return { __it, this };
      }

      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // 2354. Unnecessary copying when inserting into maps with braced-init
      iterator
      insert(const_iterator __hint, value_type&& __x)
      {
        __glibcxx_check_insert(__hint);
        size_type __bucket_count = this->bucket_count();
        auto __it = _Base::insert(__hint.base(), std::move(__x));
        _M_check_rehashed(__bucket_count);
        return { __it, this };
      }

      template<typename _Pair, typename = typename
               std::enable_if<std::is_constructible<value_type,
                                                    _Pair&&>::value>::type>
        iterator
        insert(_Pair&& __obj)
        {
          size_type __bucket_count = this->bucket_count();
          auto __it = _Base::insert(std::forward<_Pair>(__obj));
          _M_check_rehashed(__bucket_count);
          return { __it, this };
        }

      template<typename _Pair, typename = typename
               std::enable_if<std::is_constructible<value_type,
                                                    _Pair&&>::value>::type>
        iterator
        insert(const_iterator __hint, _Pair&& __obj)
        {
          __glibcxx_check_insert(__hint);
          size_type __bucket_count = this->bucket_count();
          auto __it = _Base::insert(__hint.base(), std::forward<_Pair>(__obj));
          _M_check_rehashed(__bucket_count);
          return { __it, this };
        }

      void
      insert(std::initializer_list<value_type> __l)
      { _Base::insert(__l); }

      template<typename _InputIterator>
        void
        insert(_InputIterator __first, _InputIterator __last)
        {
          typename __gnu_debug::_Distance_traits<_InputIterator>::__type __dist;
          __glibcxx_check_valid_range2(__first, __last, __dist);
          size_type __bucket_count = this->bucket_count();

          if (__dist.second >= __gnu_debug::__dp_sign)
            _Base::insert(__gnu_debug::__unsafe(__first),
                          __gnu_debug::__unsafe(__last));
          else
            _Base::insert(__first, __last);

          _M_check_rehashed(__bucket_count);
        }

#if __cplusplus > 201402L
      using node_type = typename _Base::node_type;

      node_type
      extract(const_iterator __position)
      {
        __glibcxx_check_erase(__position);
        return _M_extract(__position.base());
      }

      node_type
      extract(const key_type& __key)
      {
        const auto __position = _Base::find(__key);
        if (__position != _Base::end())
          return _M_extract(__position);
        return {};
      }

      iterator
      insert(node_type&& __nh)
      { return { _Base::insert(std::move(__nh)), this }; }

      iterator
      insert(const_iterator __hint, node_type&& __nh)
      {
        __glibcxx_check_insert(__hint);
        return { _Base::insert(__hint.base(), std::move(__nh)), this };
      }

      template<typename _H2, typename _P2>
        void
        merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>& __source)
        {
          auto __guard
            = _Safe::_S_umc_guard(std::__detail::_Select1st{}, __source);
          _Base::merge(__source);
        }

      template<typename _H2, typename _P2>
        void
        merge(unordered_multimap<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
        { merge(__source); }

      template<typename _H2, typename _P2>
        void
        merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>& __source)
        {
          auto __guard
            = _Safe::_S_uc_guard(std::__detail::_Select1st{}, __source);
          _Base::merge(__source);
        }

      template<typename _H2, typename _P2>
        void
        merge(unordered_map<_Key, _Tp, _H2, _P2, _Alloc>&& __source)
        { merge(__source); }
#endif // C++17

      using _Base::hash_function;
      using _Base::key_eq;

      iterator
      find(const key_type& __key)
      { return { _Base::find(__key), this }; }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        iterator
        find(const _Kt& __k)
        { return { _Base::find(__k), this }; }
#endif

      const_iterator
      find(const key_type& __key) const
      { return { _Base::find(__key), this }; }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        const_iterator
        find(const _Kt& __k) const
        { return { _Base::find(__k), this }; }
#endif

      using _Base::count;
#if __cplusplus > 201703L
      using _Base::contains;
#endif

      std::pair<iterator, iterator>
      equal_range(const key_type& __key)
      {
        auto __res = _Base::equal_range(__key);
        return { { __res.first, this }, { __res.second, this } };
      }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        std::pair<iterator, iterator>
        equal_range(const _Kt& __k)
        {
          auto __res = _Base::equal_range(__k);
          return { { __res.first, this }, { __res.second, this } };
        }
#endif

      std::pair<const_iterator, const_iterator>
      equal_range(const key_type& __key) const
      {
        auto __res = _Base::equal_range(__key);
        return { { __res.first, this }, { __res.second, this } };
      }

#if __cplusplus > 201703L
      template<typename _Kt,
               typename = std::__has_is_transparent_t<_Hash, _Kt>,
               typename = std::__has_is_transparent_t<_Pred, _Kt>>
        std::pair<const_iterator, const_iterator>
        equal_range(const _Kt& __k) const
        {
          auto __res = _Base::equal_range(__k);
          return { { __res.first, this }, { __res.second, this } };
        }
#endif

      size_type
      erase(const key_type& __key)
      {
        size_type __ret(0);
        size_type __bucket_count = this->bucket_count();
        auto __pair = _Base::equal_range(__key);
        for (auto __victim = __pair.first; __victim != __pair.second;)
          {
            _M_invalidate(__victim);
            __victim = _Base::erase(__victim);
            ++__ret;
          }

        _M_check_rehashed(__bucket_count);
        return __ret;
      }

      iterator
      erase(const_iterator __it)
      {
        __glibcxx_check_erase(__it);
        return { _M_erase(__it.base()), this };
      }

      _Base_iterator
      erase(_Base_const_iterator __it)
      {
        __glibcxx_check_erase2(__it);
        return _M_erase(__it);
      }

      iterator
      erase(iterator __it)
      {
        __glibcxx_check_erase(__it);
        return { _M_erase(__it.base()), this };
      }

      iterator
      erase(const_iterator __first, const_iterator __last)
      {
        __glibcxx_check_erase_range(__first, __last);
        for (auto __tmp = __first.base(); __tmp != __last.base(); ++__tmp)
          {
            _GLIBCXX_DEBUG_VERIFY(__tmp != _Base::cend(),
                                  _M_message(__gnu_debug::__msg_valid_range)
                                  ._M_iterator(__first, "first")
                                  ._M_iterator(__last, "last"));
            _M_invalidate(__tmp);
          }

        size_type __bucket_count = this->bucket_count();
        auto __next = _Base::erase(__first.base(), __last.base());
        _M_check_rehashed(__bucket_count);
        return { __next, this };
      }

      using _Base::rehash;
      using _Base::reserve;

      _Base&
      _M_base() noexcept { return *this; }

      const _Base&
      _M_base() const noexcept { return *this; }

    private:
      void
      _M_check_rehashed(size_type __prev_count)
      {
        if (__prev_count != this->bucket_count())
          this->_M_invalidate_all();
      }

      void
      _M_invalidate(_Base_const_iterator __victim)
      {
        this->_M_invalidate_if(
          [__victim](_Base_const_iterator __it) { return __it == __victim; });
        this->_M_invalidate_local_if(
          [__victim](_Base_const_local_iterator __it)
          { return __it == __victim; });
      }

      _Base_iterator
      _M_erase(_Base_const_iterator __victim)
      {
        _M_invalidate(__victim);
        size_type __bucket_count = this->bucket_count();
        _Base_iterator __next = _Base::erase(__victim);
        _M_check_rehashed(__bucket_count);
        return __next;
      }

#if __cplusplus > 201402L
      node_type
      _M_extract(_Base_const_iterator __victim)
      {
        _M_invalidate(__victim);
        return _Base::extract(__victim);
      }
#endif
    };

#if __cpp_deduction_guides >= 201606

  template<typename _InputIterator,
           typename _Hash = hash<__iter_key_t<_InputIterator>>,
           typename _Pred = equal_to<__iter_key_t<_InputIterator>>,
           typename _Allocator = allocator<__iter_to_alloc_t<_InputIterator>>,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireNotAllocator<_Pred>,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(_InputIterator, _InputIterator,
                       unordered_multimap<int, int>::size_type = {},
                       _Hash = _Hash(), _Pred = _Pred(),
                       _Allocator = _Allocator())
    -> unordered_multimap<__iter_key_t<_InputIterator>,
                          __iter_val_t<_InputIterator>, _Hash, _Pred,
                          _Allocator>;

  template<typename _Key, typename _Tp, typename _Hash = hash<_Key>,
           typename _Pred = equal_to<_Key>,
           typename _Allocator = allocator<pair<const _Key, _Tp>>,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireNotAllocator<_Pred>,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(initializer_list<pair<_Key, _Tp>>,
                       unordered_multimap<int, int>::size_type = {},
                       _Hash = _Hash(), _Pred = _Pred(),
                       _Allocator = _Allocator())
    -> unordered_multimap<_Key, _Tp, _Hash, _Pred, _Allocator>;

  template<typename _InputIterator, typename _Allocator,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(_InputIterator, _InputIterator,
                       unordered_multimap<int, int>::size_type, _Allocator)
    -> unordered_multimap<__iter_key_t<_InputIterator>,
                          __iter_val_t<_InputIterator>,
                          hash<__iter_key_t<_InputIterator>>,
                          equal_to<__iter_key_t<_InputIterator>>, _Allocator>;

  template<typename _InputIterator, typename _Allocator,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(_InputIterator, _InputIterator, _Allocator)
    -> unordered_multimap<__iter_key_t<_InputIterator>,
                          __iter_val_t<_InputIterator>,
                          hash<__iter_key_t<_InputIterator>>,
                          equal_to<__iter_key_t<_InputIterator>>, _Allocator>;

  template<typename _InputIterator, typename _Hash, typename _Allocator,
           typename = _RequireInputIter<_InputIterator>,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(_InputIterator, _InputIterator,
                       unordered_multimap<int, int>::size_type, _Hash,
                       _Allocator)
    -> unordered_multimap<__iter_key_t<_InputIterator>,
                          __iter_val_t<_InputIterator>, _Hash,
                          equal_to<__iter_key_t<_InputIterator>>, _Allocator>;

  template<typename _Key, typename _Tp, typename _Allocator,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(initializer_list<pair<_Key, _Tp>>,
                       unordered_multimap<int, int>::size_type,
                       _Allocator)
    -> unordered_multimap<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;

  template<typename _Key, typename _Tp, typename _Allocator,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(initializer_list<pair<_Key, _Tp>>, _Allocator)
    -> unordered_multimap<_Key, _Tp, hash<_Key>, equal_to<_Key>, _Allocator>;

  template<typename _Key, typename _Tp, typename _Hash, typename _Allocator,
           typename = _RequireNotAllocatorOrIntegral<_Hash>,
           typename = _RequireAllocator<_Allocator>>
    unordered_multimap(initializer_list<pair<_Key, _Tp>>,
                       unordered_multimap<int, int>::size_type,
                       _Hash, _Allocator)
    -> unordered_multimap<_Key, _Tp, _Hash, equal_to<_Key>, _Allocator>;

#if __glibcxx_containers_ranges // C++ >= 23
  template<ranges::input_range _Rg,
           __not_allocator_like _Hash = hash<__detail::__range_key_type<_Rg>>,
           __not_allocator_like _Pred = equal_to<__detail::__range_key_type<_Rg>>,
           __allocator_like _Allocator =
             allocator<__detail::__range_to_alloc_type<_Rg>>>
    unordered_multimap(from_range_t, _Rg&&,
                       unordered_multimap<int, int>::size_type = {},
                       _Hash = _Hash(), _Pred = _Pred(),
                       _Allocator = _Allocator())
    -> unordered_multimap<__detail::__range_key_type<_Rg>,
                          __detail::__range_mapped_type<_Rg>,
                          _Hash, _Pred, _Allocator>;

  template<ranges::input_range _Rg,
           __allocator_like _Allocator>
    unordered_multimap(from_range_t, _Rg&&, unordered_multimap<int, int>::size_type,
                  _Allocator)
    -> unordered_multimap<__detail::__range_key_type<_Rg>,
                          __detail::__range_mapped_type<_Rg>,
                          hash<__detail::__range_key_type<_Rg>>,
                          equal_to<__detail::__range_key_type<_Rg>>,
                          _Allocator>;

  template<ranges::input_range _Rg,
           __allocator_like _Allocator>
    unordered_multimap(from_range_t, _Rg&&, _Allocator)
    -> unordered_multimap<__detail::__range_key_type<_Rg>,
                          __detail::__range_mapped_type<_Rg>,
                          hash<__detail::__range_key_type<_Rg>>,
                          equal_to<__detail::__range_key_type<_Rg>>,
                          _Allocator>;

  template<ranges::input_range _Rg,
           __not_allocator_like _Hash,
           __allocator_like _Allocator>
    unordered_multimap(from_range_t, _Rg&&,
                       unordered_multimap<int, int>::size_type,
                       _Hash, _Allocator)
    -> unordered_multimap<__detail::__range_key_type<_Rg>,
                          __detail::__range_mapped_type<_Rg>,
                          _Hash, equal_to<__detail::__range_key_type<_Rg>>,
                          _Allocator>;
#endif
#endif

  template<typename _Key, typename _Tp, typename _Hash,
           typename _Pred, typename _Alloc>
    inline void
    swap(unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
         unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    noexcept(noexcept(__x.swap(__y)))
    { __x.swap(__y); }

  template<typename _Key, typename _Tp, typename _Hash,
           typename _Pred, typename _Alloc>
    inline bool
    operator==(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
               const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    { return __x._M_base() == __y._M_base(); }

#if __cpp_impl_three_way_comparison < 201907L
  template<typename _Key, typename _Tp, typename _Hash,
           typename _Pred, typename _Alloc>
    inline bool
    operator!=(const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __x,
               const unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>& __y)
    { return !(__x == __y); }
#endif

} // namespace __debug
} // namespace std

#endif // C++11

#endif