On Mon, 13 Apr 2015, Jonathan Wakely wrote:

> I don't have a preference, but I think the forward declarations should
> work without problems. <list> includes bits/stl_iterator_base_funcs.h
> so if the forward declarations didn't match the definitions for some
> reason we'd know right away.

Here is a new version that also passes the tests. I guess we will have 
plenty of time during stage1 to notice if it causes problems. We could 
probably move the new definitions of __distance to 
bits/stl_iterator_base_funcs.h, I don't have a clear preference.

2015-04-14  Marc Glisse  <marc.glisse@inria.fr>

 	PR libstdc++/61347
 	* include/bits/stl_iterator_base_funcs.h (_List_iterator,
 	_List_const_iterator): Declare.
 	(__distance): Declare new overloads for _List_iterator and
 	_List_const_iterator.
 	* include/bits/stl_list.h (__distance): New overloads for
 	_List_iterator and _List_const_iterator.
 	* testsuite/23_containers/list/61347.cc: New testcase.

-- 
Marc Glisse