I'm having a problem using Boost.Phoenix. I'm currently building against Boost 1.41 using gcc 4.3.2. I've simplified my use case quite a bit, so please forgive the obtuseness of the example. The following code fails to compile: ~~~~~~~~~~~~~~~~~~~~ #include #include #include #include #include <vector> #include <map> #include <algorithm> namespace phx = boost::phoenix; using namespace phx::arg_names; using phx::at_c; using std::map; using std::multimap; using std::vector; int main() { typedef map char_int_map_t; typedef multimap int_iter_map_t; typedef map char_iter_map_t; int int_key = 5; char_int_map_t int_map; int_iter_map_t int_iter_map; char_iter_map_t char_iter_map1, char_iter_map_t2; int_iter_map_t::iterator start,stop; std::pair er = int_iter_map.equal_range(int_key); std::set_intersection( char_iter_map1.begin(), char_iter_map1.end(), er.first,er.second, inserter(char_iter_map_t2,char_iter_map_t2.begin()), phx::at_c<0>(arg1) < phx::at_c<0>(*phx::at_c<1>(arg2)) // <- COMPILE FAILURE ); } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the information I can offer, 1) When the key in char_int_map_t and char_iter_map_t is a char rather than a vector<char> this compiles without problems. 2) The gcc error shows that the arguments to the generated function object are being switched (I think, see below) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ... .../comparison.hpp:29:5: error: no match for ‘operator<’ in ‘result_of_less::x < result_of_less::y’ .../comparison.hpp: In instantiation of ‘const int result_of_less::index’: .../comparison.hpp:29: instantiated from ‘result_of_less’ .../mpl/eval_if.hpp:38: instantiated from ‘eval_if, is_actor, mpl_::bool_<false>, mpl_::bool_<false>, mpl_::bool_<false> >, re_curry, result_of_less&> >’ .../comparison.hpp:39: instantiated from ‘ boost::phoenix::less_eval::result< boost::phoenix::basic_environment< std::pair< // This should be the second argument, no? const int, std::_Rb_tree_iterator, int>> >, std::pair< const std::vector< char, std::allocator<char> >, std::_Rb_tree_iterator, int>> > >, boost::phoenix::composite< boost::phoenix::at_eval<0>, boost::fusion::vector< boost::phoenix::argument<0> > >, boost::phoenix::composite< boost::phoenix::at_eval<0>, boost::fusion::vector< boost::phoenix::composite< boost::phoenix::dereference_eval, boost::fusion::vector< boost::phoenix::composite< boost::phoenix::at_eval<1>, boost::fusion::vector< boost::phoenix::argument<1> > > > > > >

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 3) Finally, if I use the expression phx::at_c<0>(arg1) < *phx::at_c<1>(arg2) the code still fails to compile (obviously), but does seem to get the arguments in the correct order. Any ideas? Thanks Nate