[boost] Problem with boost::optional and the BGL using the IBM xlC compiler

From: Matthias Troyer (troyer_at_[hidden])
Date: 2004-09-11 03:09:54

A recent change to the file  
boost/graph/detail/adj_list_edge_iterator.hpp breaks the BGL on the IBM  
xlC compiler. The change is:

revision 1.7
date: 2004/08/24 22:00:33;  author: dgregor;  state: Exp;  lines: +11  
-10
Use boost::optional to avoid copying singular iterators

The problem is that on the IBM compiler unfortunately, for some strange  
reason the destructor of boost::optional fails to compile if the type  
is an OutEdgeIterator, as can be seen in the following program that  
fails:

#include <boost/graph/adjacency_list.hpp>
using namespace boost;
int main()
{
   typedef adjacency_list<vecS,vecS,directedS> G;
   typedef boost::graph_traits<G>::out_edge_iterator OutEdgeIterator;
   boost::optional<OutEdgeIterator> edges;
}

with the horrible error messages listed below. Since I do not see how  
to fix optional to work with the OutEdgeIterator (it looks like a  
compiler bug to me), I would like to ask the BGL authors if they could  
undo this recent change, or at least undo it for the IBM compiler so  
that the BGL compiles again? Or does anybody experienced with optional  
and the IBM compiler see how to patch optional to make it work with the  
IBM compiler?

Best regards

Matthias

"boost/boost/optional/optional.hpp", line 353.66: 1540-0210 (S) "T" is  
not a base class of  
"out_edge_iter<std::_Ptrit<boost::detail::sep_<unsigned  
long,boost::no_property>,long,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &>,unsigned  
long,boost::detail::edge_desc_impl<boost::directed_tag,unsigned  
long>,long>".
"boost/boost/optional/optional.hpp", line 353.10: 1540-0700 (I) The  
previous message was produced while processing  
"boost::optional_detail::optional_base<boost::detail:: 
out_edge_iter<std::_Ptrit<boost::detail::sep_<unsigned  
long,boost::no_property>,long,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &>,unsigned  
long,boost::detail::edge_desc_impl<boost::directed_tag,unsigned  
lon...".
"boost/boost/optional/optional.hpp", line 327.11: 1540-0700 (I) The  
previous message was produced while processing  
"boost::optional_detail::optional_base<boost::detail:: 
out_edge_iter<std::_Ptrit<boost::detail::sep_<unsigned  
long,boost::no_property>,long,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &>,unsigned  
long,boost::detail::edge_desc_impl<boost::directed_tag,unsigned  
lon...".
"boost/boost/optional/optional.hpp", line 208.24: 1540-0700 (I) The  
previous message was produced while processing  
"boost::optional_detail::optional_base<boost::detail:: 
out_edge_iter<std::_Ptrit<boost::detail::sep_<unsigned  
long,boost::no_property>,long,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &>,unsigned  
long,boost::detail::edge_desc_impl<boost::directed_tag,unsigned  
lon...".
"boost/boost/optional/optional.hpp", line 130.7: 1540-0700 (I) The  
previous message was produced while processing  
"boost::optional_detail::optional_base<boost::detail:: 
out_edge_iter<std::_Ptrit<boost::detail::sep_<unsigned  
long,boost::no_property>,long,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &>,unsigned  
long,boost::detail::edge_desc_impl<boost::directed_tag,unsigned  
lon...".
"boost/boost/optional/optional.hpp", line 436.5: 1540-0700 (I) The  
previous message was produced while processing  
"boost::optional<boost::detail::out_edge_iter<std::_Ptrit<boost:: 
detail::sep_<unsigned  
long,boost::no_property>,long,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &,boost::detail::sep_<unsigned  
long,boost::no_property> *,boost::detail::sep_<unsigned  
long,boost::no_property> &>,unsigned  
long,boost::detail::edge_desc_impl<boost::directed_tag,unsigned  
long>,long> >::~optional()".
"test.C", line 8.1: 1540-0700 (I) The previous message was produced  
while processing "main()".