Index: src/debug.cc
===================================================================
--- src/debug.cc	(revision 168407)
+++ src/debug.cc	(working copy)
@@ -257,11 +257,7 @@
   _M_detach_single(_Safe_iterator_base* __it) throw ()
   {
     // Remove __it from this sequence's list
-    if (__it->_M_prior)
-      __it->_M_prior->_M_next = __it->_M_next;
-    if (__it->_M_next)
-      __it->_M_next->_M_prior = __it->_M_prior;
-	
+    __it->_M_unlink();
     if (_M_const_iterators == __it)
       _M_const_iterators = __it->_M_next;
     if (_M_iterators == __it)
Index: include/debug/safe_base.h
===================================================================
--- include/debug/safe_base.h	(revision 168407)
+++ include/debug/safe_base.h	(working copy)
@@ -146,6 +146,16 @@
     /** Reset all member variables */
     void
     _M_reset() throw ();
+
+    /** Unlink itself */
+    void
+    _M_unlink() throw ()
+    {
+      if (_M_prior)
+	_M_prior->_M_next = _M_next;
+      if (_M_next)
+	_M_next->_M_prior = _M_prior;
+    }
   };
 
   /**
Index: include/debug/forward_list
===================================================================
--- include/debug/forward_list	(revision 168407)
+++ include/debug/forward_list	(working copy)
@@ -600,9 +600,78 @@
 		   && __it != this->_M_base().cend();
 	  });
       }
+      typedef __gnu_debug::_Safe_iterator_base _Safe_iterator_base;
+      static void _M_swap_aux(forward_list& __lhs,
+			      _Safe_iterator_base*& __lhs_iterators,
+			      forward_list& __rhs,
+			      _Safe_iterator_base*& __rhs_iterators);
+      void _M_swap(forward_list& __list);
     };
 
+   template<typename _Tp, typename _Alloc>
+    void
+    forward_list<_Tp, _Alloc>::_M_swap_aux(forward_list<_Tp, _Alloc>& __lhs,
+		__gnu_debug::_Safe_iterator_base*& __lhs_iterators,
+		forward_list<_Tp, _Alloc>& __rhs,
+		__gnu_debug::_Safe_iterator_base*& __rhs_iterators)
+    {
+      using __gnu_debug::_Safe_iterator_base;
+      _Safe_iterator_base* __bbegin_its = 0;
+      _Safe_iterator_base* __last_bbegin = 0;
+      for (_Safe_iterator_base* __iter = __lhs_iterators; __iter;)
+	{
+	  const_iterator* __victim = static_cast<const_iterator*>(__iter);
+	  __iter = __iter->_M_next;
+	  if (__victim->_M_singular())
+	    continue;
+	  if (__victim->base() == __rhs._M_base().cbefore_begin())
+	    {
+	      __victim->_M_version = __rhs._M_version;
+	      __victim->_M_unlink();
+	      if (__lhs_iterators == __victim)
+		__lhs_iterators = __victim->_M_next;
+	      if (__bbegin_its)
+		{
+		  __victim->_M_next = __bbegin_its;
+		  __bbegin_its->_M_prior = __victim;
+		}
+	      else
+		__last_bbegin = __victim;
+	      __bbegin_its = __victim;
+	    }
+	  else
+	    __victim->_M_sequence = &__lhs;
+	}
+
+      if (__bbegin_its)
+	{
+	  if (__rhs_iterators)
+	    {
+	      __rhs_iterators->_M_prior = __last_bbegin;
+	      __last_bbegin->_M_next = __rhs_iterators;
+	    }
+	  __rhs_iterators = __bbegin_its;
+	}
+    }
+
+  /* Special forward_list _M_swap version that do not swap the
+   * before-begin ownership.*/
   template<typename _Tp, typename _Alloc>
+    void forward_list<_Tp, _Alloc>::_M_swap(forward_list<_Tp, _Alloc>& __list)
+      {
+	__gnu_cxx::__scoped_lock sentry(this->_M_get_mutex());
+	std::swap(this->_M_iterators, __list._M_iterators);
+	std::swap(this->_M_const_iterators, __list._M_const_iterators);
+	std::swap(this->_M_version, __list._M_version);
+	_Safe_iterator_base* __this_its = this->_M_iterators;
+	_M_swap_aux(__list, __list._M_iterators, *this, this->_M_iterators);
+	_Safe_iterator_base* __this_const_its = this->_M_const_iterators;
+	_M_swap_aux(__list, __list._M_const_iterators, *this, this->_M_const_iterators);
+	_M_swap_aux(*this, __this_its, __list, __list._M_iterators);
+	_M_swap_aux(*this, __this_const_its, __list, __list._M_const_iterators);
+      }
+
+  template<typename _Tp, typename _Alloc>
     bool
     operator==(const forward_list<_Tp, _Alloc>& __lx,
                const forward_list<_Tp, _Alloc>& __ly)
Index: testsuite/23_containers/forward_list/debug/swap.cc
===================================================================
--- testsuite/23_containers/forward_list/debug/swap.cc	(revision 168407)
+++ testsuite/23_containers/forward_list/debug/swap.cc	(working copy)
@@ -54,9 +54,7 @@
   // before-begin iterator is not transfered:
   // TODO: Validate with LWG group how before begin should be
   // treated.
-#if !_GLIBCXX_DEBUG
   VERIFY( fit == fl1_its[0] );
-#endif
   // All others are, even paste-the-end one:
   for (size_t i = 1; i != fl2_its.size(); ++i)
   {
@@ -66,9 +64,7 @@
   fit = fl2.before_begin();
   // TODO: Validate with LWG group how before begin should be
   // treated.
-#if !_GLIBCXX_DEBUG
   VERIFY( fit == fl2_its[0] );
-#endif
   for (size_t i = 1; i != fl1_its.size(); ++i)
   {
     VERIFY( ++fit == fl1_its[i] );

