I get a number of the same failures when doing a clean build of boost trunk with a recent gcc (4.6.0). libs/signals/src/named_slot_map.cpp:105:23: instantiated from here /usr/local/lib/gcc/i686-pc-linux-gnu/4.6.0/../../../../include/c++/4.6.0/bits/stl_map.h:626:9: error: call of overloaded ‘erase(std::map<boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair>, boost::function2<bool, boost::signals::detail::stored_group, boost::signals::detail::stored_group> >::iterator&)’ is ambiguous /usr/local/lib/gcc/i686-pc-linux-gnu/4.6.0/../../../../include/c++/4.6.0/bits/stl_map.h:626:9: note: candidates are: /usr/local/lib/gcc/i686-pc-linux-gnu/4.6.0/../../../../include/c++/4.6.0/bits/stl_tree.h:763:7: note: void std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::erase(std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::const_iterator) [with _Key = boost::signals::detail::stored_group, _Val = std::pair<const boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair> >, _KeyOfValue = std::_Select1st<std::pair<const boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair> > >, _Compare = boost::function2<bool, boost::signals::detail::stored_group, boost::signals::detail::stored_group>, _Alloc = std::allocator<std::pair<const boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair> > >, std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::const_iterator = std::_Rb_tree_const_iterator<std::pair<const boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair> > >] /usr/local/lib/gcc/i686-pc-linux-gnu/4.6.0/../../../../include/c++/4.6.0/bits/stl_tree.h:1490:5: note: std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::size_type std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::erase(const _Key&) [with _Key = boost::signals::detail::stored_group, _Val = std::pair<const boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair> >, _KeyOfValue = std::_Select1st<std::pair<const boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair> > >, _Compare = boost::function2<bool, boost::signals::detail::stored_group, boost::signals::detail::stored_group>, _Alloc = std::allocator<std::pair<const boost::signals::detail::stored_group, std::list<boost::signals::detail::connection_slot_pair> > >, std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::size_type = unsigned int] Patrick