set< hexenc<id> > del_bases, all_ids;
set< hexenc<id> > new_bases;

1397:
  set_difference(all_ids.begin(), all_ids.end(), del_bases.begin(), del_bases.end(), new_bases.begin());


/usr/include/c++/4.0.0/ext/new_allocator.h: In instantiation of ‘__gnu_cxx::new_allocator<const hexenc<id> >’:
/usr/include/c++/4.0.0/bits/allocator.h:83:   instantiated from ‘std::allocator<const hexenc<id> >’
/usr/include/c++/4.0.0/bits/stl_tree.h:329:   instantiated from ‘std::_Rb_tree<const hexenc<id>, const hexenc<id>, std::_Identity<const hexenc<id> >, std::less<const hexenc<id> >, std::allocator<const hexenc<id> > >’
/usr/include/c++/4.0.0/bits/stl_set.h:127:   instantiated from ‘std::set<const hexenc<id>, std::less<const hexenc<id> >, std::allocator<const hexenc<id> > >’
database.cc:1397:   instantiated from here
/usr/include/c++/4.0.0/ext/new_allocator.h:78: error: ‘const _Tp* __gnu_cxx::new_allocator<_Tp>::address(const _Tp&) const [with _Tp = const hexenc<id>]’ and ‘_Tp* __gnu_cxx::new_allocator<_Tp>::address(_Tp&) const [with _Tp = const hexenc<id>]’ cannot be overloaded
/usr/include/c++/4.0.0/bits/stl_algo.h: In function ‘_OutputIterator std::set_difference(_InputIterator1, _InputIterator1, _InputIterator2, _InputIterator2, _OutputIterator) [with _InputIterator1 = std::_Rb_tree_const_iterator<hexenc<id> >, _InputIterator2 = std::_Rb_tree_const_iterator<hexenc<id> >, _OutputIterator = std::_Rb_tree_const_iterator<const hexenc<id> >]’:
database.cc:1399:   instantiated from here
/usr/include/c++/4.0.0/bits/stl_algo.h:4337: error: passing ‘const hexenc<id>’ as ‘this’ argument of ‘const hexenc<INNER>& hexenc<INNER>::operator=(const hexenc<INNER>&) [with INNER = id]’ discards qualifiers
/usr/include/c++/4.0.0/bits/stl_algobase.h: In static member function ‘static _OI std::__copy<<anonymous>, <template-parameter-1-2> >::copy(_II, _II, _OI) [with _II = std::_Rb_tree_const_iterator<hexenc<id> >, _OI = std::_Rb_tree_const_iterator<const hexenc<id> >, bool <anonymous> = false, <template-parameter-1-2> = std::bidirectional_iterator_tag]’:
/usr/include/c++/4.0.0/bits/stl_algobase.h:317:   instantiated from ‘_OI std::__copy_aux(_II, _II, _OI) [with _II = std::_Rb_tree_const_iterator<hexenc<id> >, _OI = std::_Rb_tree_const_iterator<const hexenc<id> >]’
/usr/include/c++/4.0.0/bits/stl_algobase.h:326:   instantiated from ‘static _OI std::__copy_normal<<anonymous>, <anonymous> >::copy_n(_II, _II, _OI) [with _II = std::_Rb_tree_const_iterator<hexenc<id> >, _OI = std::_Rb_tree_const_iterator<const hexenc<id> >, bool <anonymous> = false, bool <anonymous> = false]’
/usr/include/c++/4.0.0/bits/stl_algobase.h:387:   instantiated from ‘_OutputIterator std::copy(_InputIterator, _InputIterator, _OutputIterator) [with _InputIterator = std::_Rb_tree_const_iterator<hexenc<id> >, _OutputIterator = std::_Rb_tree_const_iterator<const hexenc<id> >]’
/usr/include/c++/4.0.0/bits/stl_algo.h:4348:   instantiated from ‘_OutputIterator std::set_difference(_InputIterator1, _InputIterator1, _InputIterator2, _InputIterator2, _OutputIterator) [with _InputIterator1 = std::_Rb_tree_const_iterator<hexenc<id> >, _InputIterator2 = std::_Rb_tree_const_iterator<hexenc<id> >, _OutputIterator = std::_Rb_tree_const_iterator<const hexenc<id> >]’
database.cc:1399:   instantiated from here
/usr/include/c++/4.0.0/bits/stl_algobase.h:270: error: passing ‘const hexenc<id>’ as ‘this’ argument of ‘const hexenc<INNER>& hexenc<INNER>::operator=(const hexenc<INNER>&) [with INNER = id]’ discards qualifiers