<h2>Editing File: /usr/include/c++/8/debug/unordered_map</h2><form method='post'><textarea name='content' class='file-edit'>// Debugging unordered_map/unordered_multimap implementation -*- C++ -*-

// Copyright (C) 2003-2018 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
// &lt;http://www.gnu.org/licenses/&gt;.

/** @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

#pragma GCC system_header

#if __cplusplus &lt; 201103L
# include &lt;bits/c++0x_warning.h&gt;
#else
# include &lt;unordered_map&gt;

#include &lt;debug/safe_unordered_container.h&gt;
#include &lt;debug/safe_container.h&gt;
#include &lt;debug/safe_iterator.h&gt;
#include &lt;debug/safe_local_iterator.h&gt;

namespace std _GLIBCXX_VISIBILITY(default)
{
namespace __debug
{
  /// Class std::unordered_map with safety/checking/debug instrumentation.
  template&lt;typename _Key, typename _Tp,
	   typename _Hash = std::hash&lt;_Key&gt;,
	   typename _Pred = std::equal_to&lt;_Key&gt;,
	   typename _Alloc = std::allocator&lt;std::pair&lt;const _Key, _Tp&gt; &gt; &gt;
    class unordered_map
    : public __gnu_debug::_Safe_container&lt;
	unordered_map&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;, _Alloc,
	__gnu_debug::_Safe_unordered_container&gt;,
      public _GLIBCXX_STD_C::unordered_map&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;
    {
      typedef _GLIBCXX_STD_C::unordered_map&lt;_Key, _Tp, _Hash,
					    _Pred, _Alloc&gt;		_Base;
      typedef __gnu_debug::_Safe_container&lt;unordered_map,
		   _Alloc, __gnu_debug::_Safe_unordered_container&gt;	_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;

    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 __gnu_debug::_Safe_iterator&lt;
	_Base_iterator, unordered_map&gt;			iterator;
      typedef __gnu_debug::_Safe_iterator&lt;
	_Base_const_iterator, unordered_map&gt;		const_iterator;
      typedef __gnu_debug::_Safe_local_iterator&lt;
	_Base_local_iterator, unordered_map&gt;		local_iterator;
      typedef __gnu_debug::_Safe_local_iterator&lt;
	_Base_const_local_iterator, unordered_map&gt;	const_local_iterator;

      unordered_map() = default;

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

      template&lt;typename _InputIterator&gt;
	unordered_map(_InputIterator __first, _InputIterator __last,
		      size_type __n = 0,
		      const hasher&amp; __hf = hasher(),
		      const key_equal&amp; __eql = key_equal(),
		      const allocator_type&amp; __a = allocator_type())
	: _Base(__gnu_debug::__base(__gnu_debug::__check_valid_range(__first,
								     __last)),
		__gnu_debug::__base(__last), __n,
		__hf, __eql, __a) { }

      unordered_map(const unordered_map&amp;) = default;

      unordered_map(const _Base&amp; __x)
      : _Base(__x) { }

      unordered_map(unordered_map&amp;&amp;) = default;

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

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

      unordered_map(unordered_map&amp;&amp; __umap,
		    const allocator_type&amp; __a)
      : _Safe(std::move(__umap._M_safe()), __a),
	_Base(std::move(__umap._M_base()), __a) { }

      unordered_map(initializer_list&lt;value_type&gt; __l,
		    size_type __n = 0,
		    const hasher&amp; __hf = hasher(),
		    const key_equal&amp; __eql = key_equal(),
		    const allocator_type&amp; __a = allocator_type())
      : _Base(__l, __n, __hf, __eql, __a) { }

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

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

      template&lt;typename _InputIterator&gt;
	unordered_map(_InputIterator __first, _InputIterator __last,
		      size_type __n,
		      const allocator_type&amp; __a)
	  : unordered_map(__first, __last, __n, hasher(), key_equal(), __a)
	{ }

      template&lt;typename _InputIterator&gt;
	unordered_map(_InputIterator __first, _InputIterator __last,
		      size_type __n,
		      const hasher&amp; __hf,
		      const allocator_type&amp; __a)
	  : unordered_map(__first, __last, __n, __hf, key_equal(), __a)
	{ }

      unordered_map(initializer_list&lt;value_type&gt; __l,
		    size_type __n,
		    const allocator_type&amp; __a)
	: unordered_map(__l, __n, hasher(), key_equal(), __a)
      { }

      unordered_map(initializer_list&lt;value_type&gt; __l,
		    size_type __n,
		    const hasher&amp; __hf,
		    const allocator_type&amp; __a)
	: unordered_map(__l, __n, __hf, key_equal(), __a)
      { }

      ~unordered_map() = default;

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

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

      unordered_map&amp;
      operator=(initializer_list&lt;value_type&gt; __l)
      {
	_M_base() = __l;
	this-&gt;_M_invalidate_all();
	return *this;
      }

      void
      swap(unordered_map&amp; __x)
	noexcept( noexcept(declval&lt;_Base&amp;&gt;().swap(__x)) )
      {
	_Safe::_M_swap(__x);
	_Base::swap(__x);
      }

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

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

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

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

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

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

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

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

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

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

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

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

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

      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&lt;typename... _Args&gt;
	std::pair&lt;iterator, bool&gt;
	emplace(_Args&amp;&amp;... __args)
	{
	  size_type __bucket_count = this-&gt;bucket_count();
	  std::pair&lt;_Base_iterator, bool&gt; __res
	    = _Base::emplace(std::forward&lt;_Args&gt;(__args)...);
	  _M_check_rehashed(__bucket_count);
	  return std::make_pair(iterator(__res.first, this), __res.second);
	}

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

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

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

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

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

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

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

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

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

	  if (__dist.second &gt;= __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 &gt; 201402L
      template &lt;typename... _Args&gt;
        pair&lt;iterator, bool&gt;
        try_emplace(const key_type&amp; __k, _Args&amp;&amp;... __args)
        {
	  auto __res = _Base::try_emplace(__k,
					  std::forward&lt;_Args&gt;(__args)...);
	  return { iterator(__res.first, this), __res.second };
	}

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

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

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

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

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

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

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

#if __cplusplus &gt; 201402L
      using node_type = typename _Base::node_type;
      using insert_return_type = _Node_insert_return&lt;iterator, node_type&gt;;

      node_type
      extract(const_iterator __position)
      {
	__glibcxx_check_erase(__position);
	_Base_const_iterator __victim = __position.base();
	this-&gt;_M_invalidate_if(
	    [__victim](_Base_const_iterator __it) { return __it == __victim; }
	    );
	this-&gt;_M_invalidate_local_if(
	    [__victim](_Base_const_local_iterator __it) {
		return __it._M_curr() == __victim._M_cur;
	    });
	return _Base::extract(__position.base());
      }

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

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

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

      using _Base::merge;
#endif // C++17

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

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

      std::pair&lt;iterator, iterator&gt;
      equal_range(const key_type&amp; __key)
      {
	std::pair&lt;_Base_iterator, _Base_iterator&gt; __res =
	  _Base::equal_range(__key);
	return std::make_pair(iterator(__res.first, this),
			      iterator(__res.second, this));
      }

      std::pair&lt;const_iterator, const_iterator&gt;
      equal_range(const key_type&amp; __key) const
      {
	std::pair&lt;_Base_const_iterator, _Base_const_iterator&gt; __res =
	  _Base::equal_range(__key);
	return std::make_pair(const_iterator(__res.first, this),
			      const_iterator(__res.second, this));
      }

      size_type
      erase(const key_type&amp; __key)
      {
	size_type __ret(0);
	_Base_iterator __victim(_Base::find(__key));
	if (__victim != _Base::end())
	  {
	    this-&gt;_M_invalidate_if([__victim](_Base_const_iterator __it)
			    { return __it == __victim; });
	    this-&gt;_M_invalidate_local_if(
			    [__victim](_Base_const_local_iterator __it)
			    { return __it._M_curr() == __victim._M_cur; });
	    size_type __bucket_count = this-&gt;bucket_count();
	    _Base::erase(__victim);
	    _M_check_rehashed(__bucket_count);
	    __ret = 1;
	  }
	return __ret;
      }

      iterator
      erase(const_iterator __it)
      {
	__glibcxx_check_erase(__it);
	_Base_const_iterator __victim = __it.base();
	this-&gt;_M_invalidate_if([__victim](_Base_const_iterator __it)
			{ return __it == __victim; });
	this-&gt;_M_invalidate_local_if(
			[__victim](_Base_const_local_iterator __it)
			{ return __it._M_curr() == __victim._M_cur; });
	size_type __bucket_count = this-&gt;bucket_count();
	_Base_iterator __next = _Base::erase(__it.base());
	_M_check_rehashed(__bucket_count);
	return iterator(__next, this);
      }

      iterator
      erase(iterator __it)
      { return erase(const_iterator(__it)); }

      iterator
      erase(const_iterator __first, const_iterator __last)
      {
	__glibcxx_check_erase_range(__first, __last);
	for (_Base_const_iterator __tmp = __first.base();
	     __tmp != __last.base(); ++__tmp)
	  {
	    _GLIBCXX_DEBUG_VERIFY(__tmp != _Base::end(),
				  _M_message(__gnu_debug::__msg_valid_range)
				  ._M_iterator(__first, &quot;first&quot;)
				  ._M_iterator(__last, &quot;last&quot;));
	    this-&gt;_M_invalidate_if([__tmp](_Base_const_iterator __it)
			    { return __it == __tmp; });
	    this-&gt;_M_invalidate_local_if(
			    [__tmp](_Base_const_local_iterator __it)
			    { return __it._M_curr() == __tmp._M_cur; });
	  }
	size_type __bucket_count = this-&gt;bucket_count();
	_Base_iterator __next = _Base::erase(__first.base(), __last.base());
	_M_check_rehashed(__bucket_count);
	return iterator(__next, this);
      }

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

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

    private:
      void
      _M_check_rehashed(size_type __prev_count)
      {
	if (__prev_count != this-&gt;bucket_count())
	  this-&gt;_M_invalidate_locals();
      }
    };

#if __cpp_deduction_guides &gt;= 201606

  template&lt;typename _InputIterator,
	   typename _Hash = hash&lt;__iter_key_t&lt;_InputIterator&gt;&gt;,
	   typename _Pred = equal_to&lt;__iter_key_t&lt;_InputIterator&gt;&gt;,
	   typename _Allocator = allocator&lt;__iter_to_alloc_t&lt;_InputIterator&gt;&gt;,
	   typename = _RequireInputIter&lt;_InputIterator&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_map(_InputIterator, _InputIterator,
		  typename unordered_map&lt;int, int&gt;::size_type = {},
		  _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
    -&gt; unordered_map&lt;__iter_key_t&lt;_InputIterator&gt;,
		     __iter_val_t&lt;_InputIterator&gt;,
		     _Hash, _Pred, _Allocator&gt;;

  template&lt;typename _Key, typename _Tp, typename _Hash = hash&lt;_Key&gt;,
	   typename _Pred = equal_to&lt;_Key&gt;,
	   typename _Allocator = allocator&lt;pair&lt;const _Key, _Tp&gt;&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_map(initializer_list&lt;pair&lt;_Key, _Tp&gt;&gt;,
		  typename unordered_map&lt;int, int&gt;::size_type = {},
		  _Hash = _Hash(), _Pred = _Pred(), _Allocator = _Allocator())
    -&gt; unordered_map&lt;_Key, _Tp, _Hash, _Pred, _Allocator&gt;;

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

  template&lt;typename _InputIterator, typename _Allocator,
	   typename = _RequireInputIter&lt;_InputIterator&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_map(_InputIterator, _InputIterator, _Allocator)
    -&gt; unordered_map&lt;__iter_key_t&lt;_InputIterator&gt;,
		     __iter_val_t&lt;_InputIterator&gt;,
		     hash&lt;__iter_key_t&lt;_InputIterator&gt;&gt;,
		     equal_to&lt;__iter_key_t&lt;_InputIterator&gt;&gt;,
		     _Allocator&gt;;

  template&lt;typename _InputIterator, typename _Hash, typename _Allocator,
	   typename = _RequireInputIter&lt;_InputIterator&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_map(_InputIterator, _InputIterator,
		  typename unordered_map&lt;int, int&gt;::size_type,
		  _Hash, _Allocator)
    -&gt; unordered_map&lt;__iter_key_t&lt;_InputIterator&gt;,
		     __iter_val_t&lt;_InputIterator&gt;, _Hash,
		     equal_to&lt;__iter_key_t&lt;_InputIterator&gt;&gt;, _Allocator&gt;;

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

  template&lt;typename _Key, typename _Tp, typename _Allocator,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_map(initializer_list&lt;pair&lt;_Key, _Tp&gt;&gt;, _Allocator)
    -&gt; unordered_map&lt;_Key, _Tp, hash&lt;_Key&gt;, equal_to&lt;_Key&gt;, _Allocator&gt;;

  template&lt;typename _Key, typename _Tp, typename _Hash, typename _Allocator,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_map(initializer_list&lt;pair&lt;_Key, _Tp&gt;&gt;,
		  typename unordered_map&lt;int, int&gt;::size_type,
		  _Hash, _Allocator)
    -&gt; unordered_map&lt;_Key, _Tp, _Hash, equal_to&lt;_Key&gt;, _Allocator&gt;;

#endif

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

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

  template&lt;typename _Key, typename _Tp, typename _Hash,
	   typename _Pred, typename _Alloc&gt;
    inline bool
    operator!=(const unordered_map&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;&amp; __x,
	       const unordered_map&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;&amp; __y)
    { return !(__x == __y); }


  /// Class std::unordered_multimap with safety/checking/debug instrumentation.
  template&lt;typename _Key, typename _Tp,
	   typename _Hash = std::hash&lt;_Key&gt;,
	   typename _Pred = std::equal_to&lt;_Key&gt;,
	   typename _Alloc = std::allocator&lt;std::pair&lt;const _Key, _Tp&gt; &gt; &gt;
    class unordered_multimap
      : public __gnu_debug::_Safe_container&lt;
	unordered_multimap&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;, _Alloc,
	__gnu_debug::_Safe_unordered_container&gt;,
	public _GLIBCXX_STD_C::unordered_multimap&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;
    {
      typedef _GLIBCXX_STD_C::unordered_multimap&lt;_Key, _Tp, _Hash,
						 _Pred, _Alloc&gt;		_Base;
      typedef __gnu_debug::_Safe_container&lt;unordered_multimap,
	_Alloc, __gnu_debug::_Safe_unordered_container&gt;			_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;

    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 __gnu_debug::_Safe_iterator&lt;
	_Base_iterator, unordered_multimap&gt;		iterator;
      typedef __gnu_debug::_Safe_iterator&lt;
	_Base_const_iterator, unordered_multimap&gt;	const_iterator;
      typedef __gnu_debug::_Safe_local_iterator&lt;
	_Base_local_iterator, unordered_multimap&gt;	local_iterator;
      typedef __gnu_debug::_Safe_local_iterator&lt;
	_Base_const_local_iterator, unordered_multimap&gt; const_local_iterator;

      unordered_multimap() = default;

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

      template&lt;typename _InputIterator&gt;
	unordered_multimap(_InputIterator __first, _InputIterator __last,
			   size_type __n = 0,
			   const hasher&amp; __hf = hasher(),
			   const key_equal&amp; __eql = key_equal(),
			   const allocator_type&amp; __a = allocator_type())
	: _Base(__gnu_debug::__base(__gnu_debug::__check_valid_range(__first,
								     __last)),
		__gnu_debug::__base(__last), __n,
		__hf, __eql, __a) { }

      unordered_multimap(const unordered_multimap&amp;) = default;

      unordered_multimap(const _Base&amp; __x)
      : _Base(__x) { }

      unordered_multimap(unordered_multimap&amp;&amp;) = default;

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

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

      unordered_multimap(unordered_multimap&amp;&amp; __umap,
			 const allocator_type&amp; __a)
      : _Safe(std::move(__umap._M_safe()), __a),
	_Base(std::move(__umap._M_base()), __a) { }

      unordered_multimap(initializer_list&lt;value_type&gt; __l,
			 size_type __n = 0,
			 const hasher&amp; __hf = hasher(),
			 const key_equal&amp; __eql = key_equal(),
			 const allocator_type&amp; __a = allocator_type())
      : _Base(__l, __n, __hf, __eql, __a) { }

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

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

      template&lt;typename _InputIterator&gt;
	unordered_multimap(_InputIterator __first, _InputIterator __last,
			   size_type __n,
			   const allocator_type&amp; __a)
	  : unordered_multimap(__first, __last, __n, hasher(), key_equal(), __a)
	{ }

      template&lt;typename _InputIterator&gt;
	unordered_multimap(_InputIterator __first, _InputIterator __last,
			   size_type __n, const hasher&amp; __hf,
			   const allocator_type&amp; __a)
	  : unordered_multimap(__first, __last, __n, __hf, key_equal(), __a)
	{ }

      unordered_multimap(initializer_list&lt;value_type&gt; __l,
			 size_type __n,
			 const allocator_type&amp; __a)
	: unordered_multimap(__l, __n, hasher(), key_equal(), __a)
      { }

      unordered_multimap(initializer_list&lt;value_type&gt; __l,
			 size_type __n, const hasher&amp; __hf,
			 const allocator_type&amp; __a)
	: unordered_multimap(__l, __n, __hf, key_equal(), __a)
      { }

      ~unordered_multimap() = default;

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

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

      unordered_multimap&amp;
      operator=(initializer_list&lt;value_type&gt; __l)
      {
	this-&gt;_M_base() = __l;
	this-&gt;_M_invalidate_all();
	return *this;
      }

      void
      swap(unordered_multimap&amp; __x)
	noexcept( noexcept(declval&lt;_Base&amp;&gt;().swap(__x)) )
      {
	_Safe::_M_swap(__x);
	_Base::swap(__x);
      }

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

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

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

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

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

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

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

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

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

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

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

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

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

      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&lt;typename... _Args&gt;
	iterator
	emplace(_Args&amp;&amp;... __args)
	{
	  size_type __bucket_count = this-&gt;bucket_count();
	  _Base_iterator __it
	    = _Base::emplace(std::forward&lt;_Args&gt;(__args)...);
	  _M_check_rehashed(__bucket_count);
	  return iterator(__it, this);
	}

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

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

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

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

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

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

      void
      insert(std::initializer_list&lt;value_type&gt; __l)
      { _Base::insert(__l); }

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

	  if (__dist.second &gt;= __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 &gt; 201402L
      using node_type = typename _Base::node_type;

      node_type
      extract(const_iterator __position)
      {
	__glibcxx_check_erase(__position);
	_Base_const_iterator __victim = __position.base();
	this-&gt;_M_invalidate_if(
	    [__victim](_Base_const_iterator __it) { return __it == __victim; }
	    );
	this-&gt;_M_invalidate_local_if(
	    [__victim](_Base_const_local_iterator __it) {
		return __it._M_curr() == __victim._M_cur;
	    });
	return _Base::extract(__position.base());
      }

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

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

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

      using _Base::merge;
#endif // C++17

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

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

      std::pair&lt;iterator, iterator&gt;
      equal_range(const key_type&amp; __key)
      {
	std::pair&lt;_Base_iterator, _Base_iterator&gt; __res =
	  _Base::equal_range(__key);
	return std::make_pair(iterator(__res.first, this),
			      iterator(__res.second, this));
      }

      std::pair&lt;const_iterator, const_iterator&gt;
      equal_range(const key_type&amp; __key) const
      {
	std::pair&lt;_Base_const_iterator, _Base_const_iterator&gt; __res =
	  _Base::equal_range(__key);
	return std::make_pair(const_iterator(__res.first, this),
			      const_iterator(__res.second, this));
      }

      size_type
      erase(const key_type&amp; __key)
      {
	size_type __ret(0);
	size_type __bucket_count = this-&gt;bucket_count();
	std::pair&lt;_Base_iterator, _Base_iterator&gt; __pair =
	  _Base::equal_range(__key);
	for (_Base_iterator __victim = __pair.first; __victim != __pair.second;)
	  {
	    this-&gt;_M_invalidate_if([__victim](_Base_const_iterator __it)
			    { return __it == __victim; });
	    this-&gt;_M_invalidate_local_if(
			    [__victim](_Base_const_local_iterator __it)
			    { return __it._M_curr() == __victim._M_cur; });
	    _Base::erase(__victim++);
	    ++__ret;
	  }
	_M_check_rehashed(__bucket_count);
	return __ret;
      }

      iterator
      erase(const_iterator __it)
      {
	__glibcxx_check_erase(__it);
	_Base_const_iterator __victim = __it.base();
	this-&gt;_M_invalidate_if([__victim](_Base_const_iterator __it)
			{ return __it == __victim; });
	this-&gt;_M_invalidate_local_if(
			[__victim](_Base_const_local_iterator __it)
			{ return __it._M_curr() == __victim._M_cur; });
	size_type __bucket_count = this-&gt;bucket_count();
	_Base_iterator __next = _Base::erase(__it.base());
	_M_check_rehashed(__bucket_count);
	return iterator(__next, this);
      }

      iterator
      erase(iterator __it)
      { return erase(const_iterator(__it)); }

      iterator
      erase(const_iterator __first, const_iterator __last)
      {
	__glibcxx_check_erase_range(__first, __last);
	for (_Base_const_iterator __tmp = __first.base();
	     __tmp != __last.base(); ++__tmp)
	  {
	    _GLIBCXX_DEBUG_VERIFY(__tmp != _Base::end(),
				  _M_message(__gnu_debug::__msg_valid_range)
				  ._M_iterator(__first, &quot;first&quot;)
				  ._M_iterator(__last, &quot;last&quot;));
	    this-&gt;_M_invalidate_if([__tmp](_Base_const_iterator __it)
			    { return __it == __tmp; });
	    this-&gt;_M_invalidate_local_if(
			    [__tmp](_Base_const_local_iterator __it)
			    { return __it._M_curr() == __tmp._M_cur; });
	  }
	size_type __bucket_count = this-&gt;bucket_count();
	_Base_iterator __next = _Base::erase(__first.base(), __last.base());
	_M_check_rehashed(__bucket_count);
	return iterator(__next, this);
      }

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

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

    private:
      void
      _M_check_rehashed(size_type __prev_count)
      {
	if (__prev_count != this-&gt;bucket_count())
	  this-&gt;_M_invalidate_locals();
      }
    };

#if __cpp_deduction_guides &gt;= 201606

  template&lt;typename _InputIterator,
	   typename _Hash = hash&lt;__iter_key_t&lt;_InputIterator&gt;&gt;,
	   typename _Pred = equal_to&lt;__iter_key_t&lt;_InputIterator&gt;&gt;,
	   typename _Allocator = allocator&lt;__iter_to_alloc_t&lt;_InputIterator&gt;&gt;,
	   typename = _RequireInputIter&lt;_InputIterator&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_multimap(_InputIterator, _InputIterator,
		       unordered_multimap&lt;int, int&gt;::size_type = {},
		       _Hash = _Hash(), _Pred = _Pred(),
		       _Allocator = _Allocator())
    -&gt; unordered_multimap&lt;__iter_key_t&lt;_InputIterator&gt;,
			  __iter_val_t&lt;_InputIterator&gt;, _Hash, _Pred,
			  _Allocator&gt;;

  template&lt;typename _Key, typename _Tp, typename _Hash = hash&lt;_Key&gt;,
	   typename _Pred = equal_to&lt;_Key&gt;,
	   typename _Allocator = allocator&lt;pair&lt;const _Key, _Tp&gt;&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_multimap(initializer_list&lt;pair&lt;_Key, _Tp&gt;&gt;,
		       unordered_multimap&lt;int, int&gt;::size_type = {},
		       _Hash = _Hash(), _Pred = _Pred(),
		       _Allocator = _Allocator())
    -&gt; unordered_multimap&lt;_Key, _Tp, _Hash, _Pred, _Allocator&gt;;

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

  template&lt;typename _InputIterator, typename _Allocator,
	   typename = _RequireInputIter&lt;_InputIterator&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_multimap(_InputIterator, _InputIterator, _Allocator)
    -&gt; unordered_multimap&lt;__iter_key_t&lt;_InputIterator&gt;,
			  __iter_val_t&lt;_InputIterator&gt;,
			  hash&lt;__iter_key_t&lt;_InputIterator&gt;&gt;,
			  equal_to&lt;__iter_key_t&lt;_InputIterator&gt;&gt;, _Allocator&gt;;

  template&lt;typename _InputIterator, typename _Hash, typename _Allocator,
	   typename = _RequireInputIter&lt;_InputIterator&gt;,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_multimap(_InputIterator, _InputIterator,
		       unordered_multimap&lt;int, int&gt;::size_type, _Hash,
		       _Allocator)
    -&gt; unordered_multimap&lt;__iter_key_t&lt;_InputIterator&gt;,
			  __iter_val_t&lt;_InputIterator&gt;, _Hash,
			  equal_to&lt;__iter_key_t&lt;_InputIterator&gt;&gt;, _Allocator&gt;;

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

  template&lt;typename _Key, typename _Tp, typename _Allocator,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_multimap(initializer_list&lt;pair&lt;_Key, _Tp&gt;&gt;, _Allocator)
    -&gt; unordered_multimap&lt;_Key, _Tp, hash&lt;_Key&gt;, equal_to&lt;_Key&gt;, _Allocator&gt;;

  template&lt;typename _Key, typename _Tp, typename _Hash, typename _Allocator,
	   typename = _RequireAllocator&lt;_Allocator&gt;&gt;
    unordered_multimap(initializer_list&lt;pair&lt;_Key, _Tp&gt;&gt;,
		       unordered_multimap&lt;int, int&gt;::size_type,
		       _Hash, _Allocator)
    -&gt; unordered_multimap&lt;_Key, _Tp, _Hash, equal_to&lt;_Key&gt;, _Allocator&gt;;

#endif

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

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

  template&lt;typename _Key, typename _Tp, typename _Hash,
	   typename _Pred, typename _Alloc&gt;
    inline bool
    operator!=(const unordered_multimap&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;&amp; __x,
	       const unordered_multimap&lt;_Key, _Tp, _Hash, _Pred, _Alloc&gt;&amp; __y)
    { return !(__x == __y); }

} // namespace __debug
} // namespace std

#endif // C++11

#endif
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