]> git.ipfire.org Git - thirdparty/gcc.git/blobdiff - libstdc++-v3/include/bits/forward_list.tcc
PR libstdc++/90105 make forward_list::sort stable
[thirdparty/gcc.git] / libstdc++-v3 / include / bits / forward_list.tcc
index e3af42e12dd9b948187b9ff185b28b86d0123449..088111e3330e5409738d02e2b8946c6b084aeb1d 100644 (file)
@@ -1,6 +1,6 @@
 // <forward_list.tcc> -*- C++ -*-
 
-// Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2008-2019 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
 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 // <http://www.gnu.org/licenses/>.
 
-/** @file forward_list.tcc
- *  This is a Standard C++ Library header.
+/** @file bits/forward_list.tcc
+ *  This is an internal header file, included by other library headers.
+ *  Do not attempt to use it directly. @headername{forward_list}
  */
 
 #ifndef _FORWARD_LIST_TCC
 #define _FORWARD_LIST_TCC 1
 
-_GLIBCXX_BEGIN_NAMESPACE(std)
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
   template<typename _Tp, typename _Alloc>
     _Fwd_list_base<_Tp, _Alloc>::
-    _Fwd_list_base(const _Fwd_list_base& __lst, const _Alloc& __a)
-    : _M_impl(__a)
+    _Fwd_list_base(_Fwd_list_base&& __lst, _Node_alloc_type&& __a)
+    : _M_impl(std::move(__a))
     {
-      this->_M_impl._M_head._M_next = 0;
-      _Fwd_list_node_base* __to = &this->_M_impl._M_head;
-      _Node* __curr = static_cast<_Node*>(__lst._M_impl._M_head._M_next);
-
-      while (__curr)
-        {
-          __to->_M_next = _M_create_node(__curr->_M_value);
-          __to = __to->_M_next;
-          __curr = static_cast<_Node*>(__curr->_M_next);
-        }
+      if (__lst._M_get_Node_allocator() == _M_get_Node_allocator())
+       this->_M_impl._M_head = std::move(__lst._M_impl._M_head);
     }
 
   template<typename _Tp, typename _Alloc>
@@ -54,84 +50,88 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
       _Fwd_list_base<_Tp, _Alloc>::
       _M_insert_after(const_iterator __pos, _Args&&... __args)
       {
-        _Fwd_list_node_base* __to
+       _Fwd_list_node_base* __to
          = const_cast<_Fwd_list_node_base*>(__pos._M_node);
        _Node* __thing = _M_create_node(std::forward<_Args>(__args)...);
-        __thing->_M_next = __to->_M_next;
-        __to->_M_next = __thing;
-        return __to->_M_next;
+       __thing->_M_next = __to->_M_next;
+       __to->_M_next = __thing;
+       return __to->_M_next;
       }
 
   template<typename _Tp, typename _Alloc>
-    void
+    _Fwd_list_node_base*
     _Fwd_list_base<_Tp, _Alloc>::
     _M_erase_after(_Fwd_list_node_base* __pos)
     {
       _Node* __curr = static_cast<_Node*>(__pos->_M_next);
       __pos->_M_next = __curr->_M_next;
-      _M_get_Node_allocator().destroy(__curr);
+      _Node_alloc_traits::destroy(_M_get_Node_allocator(),
+                                 __curr->_M_valptr());
+      __curr->~_Node();
       _M_put_node(__curr);
+      return __pos->_M_next;
     }
 
   template<typename _Tp, typename _Alloc>
-    void
+    _Fwd_list_node_base*
     _Fwd_list_base<_Tp, _Alloc>::
-    _M_erase_after(_Fwd_list_node_base* __pos, 
-                   _Fwd_list_node_base* __last)
+    _M_erase_after(_Fwd_list_node_base* __pos,
+                  _Fwd_list_node_base* __last)
     {
       _Node* __curr = static_cast<_Node*>(__pos->_M_next);
       while (__curr != __last)
-        {
-          _Node* __temp = __curr;
-          __curr = static_cast<_Node*>(__curr->_M_next);
-          _M_get_Node_allocator().destroy(__temp);
-          _M_put_node(__temp);
-        }
+       {
+         _Node* __temp = __curr;
+         __curr = static_cast<_Node*>(__curr->_M_next);
+         _Node_alloc_traits::destroy(_M_get_Node_allocator(),
+                                     __temp->_M_valptr());
+         __temp->~_Node();
+         _M_put_node(__temp);
+       }
       __pos->_M_next = __last;
+      return __last;
     }
-  
-  // Called by the range constructor to implement [23.1.1]/9
+
+  // Called by the range constructor to implement [23.3.4.2]/9
   template<typename _Tp, typename _Alloc>
     template<typename _InputIterator>
       void
       forward_list<_Tp, _Alloc>::
-      _M_initialize_dispatch(_InputIterator __first, _InputIterator __last,
-                             __false_type)
+      _M_range_initialize(_InputIterator __first, _InputIterator __last)
       {
-        _Node_base* __to = &this->_M_impl._M_head;
-        for (; __first != __last; ++__first)
-          {
-            __to->_M_next = this->_M_create_node(*__first);
-            __to = __to->_M_next;
-          }
+       _Node_base* __to = &this->_M_impl._M_head;
+       for (; __first != __last; ++__first)
+         {
+           __to->_M_next = this->_M_create_node(*__first);
+           __to = __to->_M_next;
+         }
       }
 
-  // Called by forward_list(n,v,a), and the range constructor
-  // when it turns out to be the same thing.
+  // Called by forward_list(n,v,a).
   template<typename _Tp, typename _Alloc>
     void
     forward_list<_Tp, _Alloc>::
     _M_fill_initialize(size_type __n, const value_type& __value)
     {
       _Node_base* __to = &this->_M_impl._M_head;
-      for (; __n > 0; --__n)
-        {
-          __to->_M_next = this->_M_create_node(__value);
-          __to = __to->_M_next;
-        }
+      for (; __n; --__n)
+       {
+         __to->_M_next = this->_M_create_node(__value);
+         __to = __to->_M_next;
+       }
     }
 
   template<typename _Tp, typename _Alloc>
+    void
     forward_list<_Tp, _Alloc>::
-    forward_list(size_type __n)
-    : _Base()
+    _M_default_initialize(size_type __n)
     {
       _Node_base* __to = &this->_M_impl._M_head;
-      for (; __n > 0; --__n)
-        {
-          __to->_M_next = this->_M_create_node();
-          __to = __to->_M_next;
-        }
+      for (; __n; --__n)
+       {
+         __to->_M_next = this->_M_create_node();
+         __to = __to->_M_next;
+       }
     }
 
   template<typename _Tp, typename _Alloc>
@@ -139,28 +139,43 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
     forward_list<_Tp, _Alloc>::
     operator=(const forward_list& __list)
     {
-      if (&__list != this)
-        {
-          iterator __prev1 = before_begin();
-          iterator __curr1 = begin();
-          iterator __last1 = end();
-          const_iterator __first2 = __list.cbegin();
-          const_iterator __last2 = __list.cend();
-          while (__curr1 != __last1 && __first2 != __last2)
-            {
-              *__curr1 = *__first2;
-              ++__prev1;
-              ++__curr1;
-              ++__first2;
-            }
-          if (__first2 == __last2)
-            erase_after(__prev1, __last1);
-          else
-            insert_after(__prev1, __first2, __last2);
-        }
+      if (std::__addressof(__list) != this)
+       {
+         if (_Node_alloc_traits::_S_propagate_on_copy_assign())
+           {
+             auto& __this_alloc = this->_M_get_Node_allocator();
+             auto& __that_alloc = __list._M_get_Node_allocator();
+             if (!_Node_alloc_traits::_S_always_equal()
+                 && __this_alloc != __that_alloc)
+               {
+                 // replacement allocator cannot free existing storage
+                 clear();
+               }
+             std::__alloc_on_copy(__this_alloc, __that_alloc);
+           }
+         assign(__list.cbegin(), __list.cend());
+       }
       return *this;
     }
 
+  template<typename _Tp, typename _Alloc>
+    void
+    forward_list<_Tp, _Alloc>::
+    _M_default_insert_after(const_iterator __pos, size_type __n)
+    {
+      const_iterator __saved_pos = __pos;
+      __try
+       {
+         for (; __n; --__n)
+           __pos = emplace_after(__pos);
+       }
+      __catch(...)
+       {
+         erase_after(__saved_pos, ++__pos);
+         __throw_exception_again;
+       }
+    }
+
   template<typename _Tp, typename _Alloc>
     void
     forward_list<_Tp, _Alloc>::
@@ -170,158 +185,229 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
 
       size_type __len = 0;
       while (__k._M_next() != end() && __len < __sz)
-        {
-          ++__k;
-          ++__len;
-        }
-      if (__len == __sz)
-        erase_after(__k, end());
-      else
        {
-         forward_list __tmp(__sz - __len);
-         splice_after(__k, std::move(__tmp));
+         ++__k;
+         ++__len;
        }
+      if (__len == __sz)
+       erase_after(__k, end());
+      else
+       _M_default_insert_after(__k, __sz - __len);
     }
 
   template<typename _Tp, typename _Alloc>
     void
     forward_list<_Tp, _Alloc>::
-    resize(size_type __sz, value_type __val)
+    resize(size_type __sz, const value_type& __val)
     {
       iterator __k = before_begin();
 
       size_type __len = 0;
       while (__k._M_next() != end() && __len < __sz)
-        {
-          ++__k;
-          ++__len;
-        }
+       {
+         ++__k;
+         ++__len;
+       }
       if (__len == __sz)
-        erase_after(__k, end());
+       erase_after(__k, end());
       else
-        insert_after(__k, __sz - __len, __val);
+       insert_after(__k, __sz - __len, __val);
     }
 
   template<typename _Tp, typename _Alloc>
-    void
+    typename forward_list<_Tp, _Alloc>::iterator
     forward_list<_Tp, _Alloc>::
-    splice_after(const_iterator __pos, forward_list&& __list)
+    _M_splice_after(const_iterator __pos,
+                   const_iterator __before, const_iterator __last)
     {
-      if (!__list.empty() && &__list != this)
-        {
-          _Node_base* __tmp = const_cast<_Node_base*>(__pos._M_node);
-          const_iterator __before = __list.cbefore_begin();
-          __tmp->_M_transfer_after(const_cast<_Node_base*>(__before._M_node));
-        }
+      _Node_base* __tmp = const_cast<_Node_base*>(__pos._M_node);
+      _Node_base* __b = const_cast<_Node_base*>(__before._M_node);
+      _Node_base* __end = __b;
+
+      while (__end && __end->_M_next != __last._M_node)
+       __end = __end->_M_next;
+
+      if (__b != __end)
+       return iterator(__tmp->_M_transfer_after(__b, __end));
+      else
+       return iterator(__tmp);
     }
 
   template<typename _Tp, typename _Alloc>
     void
     forward_list<_Tp, _Alloc>::
-    splice_after(const_iterator __pos, forward_list&& __list,
-                 const_iterator __before, const_iterator __last)
+    splice_after(const_iterator __pos, forward_list&&,
+                const_iterator __i) noexcept
     {
+      const_iterator __j = __i;
+      ++__j;
+
+      if (__pos == __i || __pos == __j)
+       return;
+
       _Node_base* __tmp = const_cast<_Node_base*>(__pos._M_node);
-      __tmp->_M_transfer_after(const_cast<_Node_base*>(__before._M_node),
-                               const_cast<_Node_base*>(__last._M_node));
+      __tmp->_M_transfer_after(const_cast<_Node_base*>(__i._M_node),
+                              const_cast<_Node_base*>(__j._M_node));
     }
 
   template<typename _Tp, typename _Alloc>
-    void
+    typename forward_list<_Tp, _Alloc>::iterator
+    forward_list<_Tp, _Alloc>::
+    insert_after(const_iterator __pos, size_type __n, const _Tp& __val)
+    {
+      if (__n)
+       {
+         forward_list __tmp(__n, __val, get_allocator());
+         return _M_splice_after(__pos, __tmp.before_begin(), __tmp.end());
+       }
+      else
+       return iterator(const_cast<_Node_base*>(__pos._M_node));
+    }
+
+  template<typename _Tp, typename _Alloc>
+    template<typename _InputIterator, typename>
+      typename forward_list<_Tp, _Alloc>::iterator
+      forward_list<_Tp, _Alloc>::
+      insert_after(const_iterator __pos,
+                  _InputIterator __first, _InputIterator __last)
+      {
+       forward_list __tmp(__first, __last, get_allocator());
+       if (!__tmp.empty())
+         return _M_splice_after(__pos, __tmp.before_begin(), __tmp.end());
+       else
+         return iterator(const_cast<_Node_base*>(__pos._M_node));
+      }
+
+#if __cplusplus > 201703L
+# define _GLIBCXX20_ONLY(__expr) __expr
+#else
+# define _GLIBCXX20_ONLY(__expr)
+#endif
+
+  template<typename _Tp, typename _Alloc>
+    auto
     forward_list<_Tp, _Alloc>::
-    remove(const _Tp& __val)
+    remove(const _Tp& __val) -> __remove_return_type
     {
-      _Node* __curr = static_cast<_Node*>(&this->_M_impl._M_head);
-      while (_Node* __temp = static_cast<_Node*>(__curr->_M_next))
-        {
-          if (__temp->_M_value == __val)
-            this->_M_erase_after(__curr);
-          else
-            __curr = static_cast<_Node*>(__curr->_M_next);
-        }
+      size_type __removed __attribute__((__unused__)) = 0;
+      _Node_base* __curr = &this->_M_impl._M_head;
+      _Node_base* __extra = nullptr;
+
+      while (_Node* __tmp = static_cast<_Node*>(__curr->_M_next))
+       {
+         if (*__tmp->_M_valptr() == __val)
+           {
+             if (__tmp->_M_valptr() != std::__addressof(__val))
+               {
+                 this->_M_erase_after(__curr);
+                 _GLIBCXX20_ONLY( __removed++ );
+                 continue;
+               }
+             else
+               __extra = __curr;
+           }
+         __curr = __curr->_M_next;
+       }
+
+      if (__extra)
+       {
+         this->_M_erase_after(__extra);
+         _GLIBCXX20_ONLY( __removed++ );
+       }
+      return _GLIBCXX20_ONLY( __removed );
     }
 
   template<typename _Tp, typename _Alloc>
     template<typename _Pred>
-      void
+      auto
       forward_list<_Tp, _Alloc>::
-      remove_if(_Pred __pred)
+      remove_if(_Pred __pred) -> __remove_return_type
       {
-       _Node* __curr = static_cast<_Node*>(&this->_M_impl._M_head);
-        while (_Node* __temp = static_cast<_Node*>(__curr->_M_next))
-          {
-            if (__pred(__temp->_M_value))
-              this->_M_erase_after(__curr);
-            else
-              __curr = static_cast<_Node*>(__curr->_M_next);
-          }
+       size_type __removed __attribute__((__unused__)) = 0;
+       _Node_base* __curr = &this->_M_impl._M_head;
+       while (_Node* __tmp = static_cast<_Node*>(__curr->_M_next))
+         {
+           if (__pred(*__tmp->_M_valptr()))
+             {
+               this->_M_erase_after(__curr);
+               _GLIBCXX20_ONLY( __removed++ );
+             }
+           else
+             __curr = __curr->_M_next;
+         }
+       return _GLIBCXX20_ONLY( __removed );
       }
 
   template<typename _Tp, typename _Alloc>
     template<typename _BinPred>
-      void
+      auto
       forward_list<_Tp, _Alloc>::
-      unique(_BinPred __binary_pred)
+      unique(_BinPred __binary_pred) -> __remove_return_type
       {
-        iterator __first = begin();
-        iterator __last = end();
-        if (__first == __last)
-          return;
-        iterator __next = __first;
-        while (++__next != __last)
-        {
-          if (__binary_pred(*__first, *__next))
-            erase_after(__first);
-          else
-            __first = __next;
-          __next = __first;
-        }
+       iterator __first = begin();
+       iterator __last = end();
+       if (__first == __last)
+         return _GLIBCXX20_ONLY(0);
+       size_type __removed __attribute__((__unused__)) = 0;
+       iterator __next = __first;
+       while (++__next != __last)
+       {
+         if (__binary_pred(*__first, *__next))
+           {
+             erase_after(__first);
+             _GLIBCXX20_ONLY( __removed++ );
+           }
+         else
+           __first = __next;
+         __next = __first;
+       }
+        return _GLIBCXX20_ONLY( __removed );
       }
 
+#undef _GLIBCXX20_ONLY
+
   template<typename _Tp, typename _Alloc>
     template<typename _Comp>
       void
       forward_list<_Tp, _Alloc>::
       merge(forward_list&& __list, _Comp __comp)
       {
-        _Node_base* __node = &this->_M_impl._M_head;
-        while (__node->_M_next && __list._M_impl._M_head._M_next)
-          {
-            if (__comp(static_cast<_Node*>
-                       (__list._M_impl._M_head._M_next)->_M_value,
-                       static_cast<_Node*>
-                       (__node->_M_next)->_M_value))
-              __node->_M_transfer_after(&__list._M_impl._M_head,
-                                        __list._M_impl._M_head._M_next);
-            __node = __node->_M_next;
-          }
-        if (__list._M_impl._M_head._M_next)
-          {
-            __node->_M_next = __list._M_impl._M_head._M_next;
-            __list._M_impl._M_head._M_next = 0;
-          }
+       _Node_base* __node = &this->_M_impl._M_head;
+       while (__node->_M_next && __list._M_impl._M_head._M_next)
+         {
+           if (__comp(*static_cast<_Node*>
+                      (__list._M_impl._M_head._M_next)->_M_valptr(),
+                      *static_cast<_Node*>
+                      (__node->_M_next)->_M_valptr()))
+             __node->_M_transfer_after(&__list._M_impl._M_head,
+                                       __list._M_impl._M_head._M_next);
+           __node = __node->_M_next;
+         }
+
+       if (__list._M_impl._M_head._M_next)
+         *__node = std::move(__list._M_impl._M_head);
       }
 
   template<typename _Tp, typename _Alloc>
     bool
     operator==(const forward_list<_Tp, _Alloc>& __lx,
-               const forward_list<_Tp, _Alloc>& __ly)
+              const forward_list<_Tp, _Alloc>& __ly)
     {
       //  We don't have size() so we need to walk through both lists
       //  making sure both iterators are valid.
       auto __ix = __lx.cbegin();
       auto __iy = __ly.cbegin();
       while (__ix != __lx.cend() && __iy != __ly.cend())
-        {
-          if (*__ix != *__iy)
-            return false;
-          ++__ix;
-          ++__iy;
-        }
+       {
+         if (!(*__ix == *__iy))
+           return false;
+         ++__ix;
+         ++__iy;
+       }
       if (__ix == __lx.cend() && __iy == __ly.cend())
-        return true;
+       return true;
       else
-        return false;
+       return false;
     }
 
   template<typename _Tp, class _Alloc>
@@ -330,101 +416,102 @@ _GLIBCXX_BEGIN_NAMESPACE(std)
       forward_list<_Tp, _Alloc>::
       sort(_Comp __comp)
       {
-        // If `next' is 0, return immediately.
-        _Node* __list = static_cast<_Node*>(this->_M_impl._M_head._M_next);
-        if (!__list)
-          return;
-
-        unsigned long __insize = 1;
-
-        while (1)
-          {
-            _Node* __p = __list;
-            __list = 0;
-            _Node* __tail = 0;
-
-            // Count number of merges we do in this pass.
-            unsigned long __nmerges = 0;
-
-            while (__p)
-              {
-                ++__nmerges;
-                // There exists a merge to be done.
-                // Step `insize' places along from p.
-                _Node* __q = __p;
-                unsigned long __psize = 0;
-                for (unsigned long __i = 0; __i < __insize; ++__i)
-                  {
-                    ++__psize;
-                    __q = static_cast<_Node*>(__q->_M_next);
-                    if (!__q)
-                      break;
-                  }
-
-                // If q hasn't fallen off end, we have two lists to merge.
-                unsigned long __qsize = __insize;
-
-                // Now we have two lists; merge them.
-                while (__psize > 0 || (__qsize > 0 && __q))
-                  {
-                    // Decide whether next node of merge comes from p or q.
-                    _Node* __e;
-                    if (__psize == 0)
-                      {
-                        // p is empty; e must come from q.
-                        __e = __q;
-                        __q = static_cast<_Node*>(__q->_M_next);
-                        --__qsize;
-                      }
-                    else if (__qsize == 0 || !__q)
-                      {
-                        // q is empty; e must come from p.
-                        __e = __p;
-                        __p = static_cast<_Node*>(__p->_M_next);
-                        --__psize;
-                      }
-                    else if (__comp(__p->_M_value, __q->_M_value))
-                      {
-                        // First node of p is lower; e must come from p.
-                        __e = __p;
-                        __p = static_cast<_Node*>(__p->_M_next);
-                        --__psize;
-                      }
-                    else
-                      {
-                        // First node of q is lower; e must come from q.
-                        __e = __q;
-                        __q = static_cast<_Node*>(__q->_M_next);
-                        --__qsize;
-                      }
-
-                    // Add the next node to the merged list.
-                    if (__tail)
-                      __tail->_M_next = __e;
-                    else
-                      __list = __e;
-                    __tail = __e;
-                  }
-
-                // Now p has stepped `insize' places along, and q has too.
-                __p = __q;
-              }
-            __tail->_M_next = 0;
-
-            // If we have done only one merge, we're finished.
-            // Allow for nmerges == 0, the empty list case.
-            if (__nmerges <= 1)
-              {
-                this->_M_impl._M_head._M_next = __list;
-                return;
-              }
-
-            // Otherwise repeat, merging lists twice the size.
-            __insize *= 2;
-          }
+       // If `next' is nullptr, return immediately.
+       _Node* __list = static_cast<_Node*>(this->_M_impl._M_head._M_next);
+       if (!__list)
+         return;
+
+       unsigned long __insize = 1;
+
+       while (1)
+         {
+           _Node* __p = __list;
+           __list = nullptr;
+           _Node* __tail = nullptr;
+
+           // Count number of merges we do in this pass.
+           unsigned long __nmerges = 0;
+
+           while (__p)
+             {
+               ++__nmerges;
+               // There exists a merge to be done.
+               // Step `insize' places along from p.
+               _Node* __q = __p;
+               unsigned long __psize = 0;
+               for (unsigned long __i = 0; __i < __insize; ++__i)
+                 {
+                   ++__psize;
+                   __q = static_cast<_Node*>(__q->_M_next);
+                   if (!__q)
+                     break;
+                 }
+
+               // If q hasn't fallen off end, we have two lists to merge.
+               unsigned long __qsize = __insize;
+
+               // Now we have two lists; merge them.
+               while (__psize > 0 || (__qsize > 0 && __q))
+                 {
+                   // Decide whether next node of merge comes from p or q.
+                   _Node* __e;
+                   if (__psize == 0)
+                     {
+                       // p is empty; e must come from q.
+                       __e = __q;
+                       __q = static_cast<_Node*>(__q->_M_next);
+                       --__qsize;
+                     }
+                   else if (__qsize == 0 || !__q)
+                     {
+                       // q is empty; e must come from p.
+                       __e = __p;
+                       __p = static_cast<_Node*>(__p->_M_next);
+                       --__psize;
+                     }
+                   else if (!__comp(*__q->_M_valptr(), *__p->_M_valptr()))
+                     {
+                       // First node of q is not lower; e must come from p.
+                       __e = __p;
+                       __p = static_cast<_Node*>(__p->_M_next);
+                       --__psize;
+                     }
+                   else
+                     {
+                       // First node of q is lower; e must come from q.
+                       __e = __q;
+                       __q = static_cast<_Node*>(__q->_M_next);
+                       --__qsize;
+                     }
+
+                   // Add the next node to the merged list.
+                   if (__tail)
+                     __tail->_M_next = __e;
+                   else
+                     __list = __e;
+                   __tail = __e;
+                 }
+
+               // Now p has stepped `insize' places along, and q has too.
+               __p = __q;
+             }
+           __tail->_M_next = nullptr;
+
+           // If we have done only one merge, we're finished.
+           // Allow for nmerges == 0, the empty list case.
+           if (__nmerges <= 1)
+             {
+               this->_M_impl._M_head._M_next = __list;
+               return;
+             }
+
+           // Otherwise repeat, merging lists twice the size.
+           __insize *= 2;
+         }
       }
-_GLIBCXX_END_NAMESPACE // namespace std
 
-#endif /* _FORWARD_LIST_TCC */
+_GLIBCXX_END_NAMESPACE_CONTAINER
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
 
+#endif /* _FORWARD_LIST_TCC */