Hello, I am running into a problem where an unqualified call to begin() on a range type whose template parameters include a Boost.Phoenix type (for examle filtered_range<Pred, R> where Pred is a phoenix function) is ambiguous because, in addition to the intended std::begin, phoenix::begin is being found by ADL. What can be done about this? There exists precedent for placing boost::xxx::begin/end functions in ADL barrier namespaces because C++11 encourages unqualified calls to begin/end (specifically, this was done for boost::range::begin/end). Should the same thing be done for Phoenix? Here is a minimal example that reproduces the problem: #include <iterator> #include <boost/range/adaptor/filtered.hpp> #include <boost/phoenix/phoenix.hpp> using std::begin; int main() { using boost::phoenix::arg_names::arg1; using boost::adaptors::filtered; int v[5]; const auto& f = v | filtered(arg1 < 0); begin(f); } And here are the errors, with GCC 4.7: test.cpp: In function 'int main()': test.cpp:15:12: error: call of overloaded 'begin( const boost::range_detail::filtered_range< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less , boost::proto::argsns_::list2< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal , boost::proto::argsns_::term< boost::phoenix::argument<1> >, 0l > >, boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal , boost::proto::argsns_::term<int>, 0l > > >, 2l > >, int [5] > & )' is ambiguous test.cpp:15:12: candidates are: In file included from string:53:0, from c++/4.7.0/bits/locale_classes.h:42, from ios_base.h:43, [STL Decryptor: Suppressed 3 more STL standard header messages] from test.cpp:1: c++/4.7.0/bits/range_access.h:58:5: decltype ( __cont.begin() ) begin( const boost::range_detail::filtered_range< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost::proto::argsns_ ::list2< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term< boost::phoenix::argument<1> >, 0l> >, boost ::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term<int>, 0l> > >, 2l> >, int [5]>; decltype (__cont.begin()) = boost::filter_iterator< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost::proto::argsns_ ::list2< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term< boost::phoenix::argument<1> >, 0l> >, boost ::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term<int>, 0l> > >, 2l> >, int *> &) c++/4.7.0/bits/range_access.h:48:5: decltype ( __cont.begin() ) begin( const boost::range_detail::filtered_range< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost::proto::argsns_ ::list2< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term< boost::phoenix::argument<1> >, 0l> >, boost ::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term<int>, 0l> > >, 2l> >, int [5]>; decltype (__cont.begin()) = boost::filter_iterator< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost::proto::argsns_ ::list2< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term< boost::phoenix::argument<1> >, 0l> >, boost ::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term<int>, 0l> > >, 2l> >, int *> &) In file included from boost/boost/phoenix/stl/container.hpp:11:0, from boost/boost/phoenix/stl.hpp:16, from boost/boost/phoenix/phoenix.hpp:18, from test.cpp:4: boost/boost/phoenix/stl/container/container.hpp:794:1: const boost ::phoenix::detail::expression::function_eval< boost::phoenix::stl::begin, boost::range_detail::filtered_range< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost::proto::argsns_ ::list2< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term< boost::phoenix::argument<1> >, 0l> >, boost ::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term<int>, 0l> > >, 2l> >, int [5]>; boost::phoenix::detail::expression::function_eval< boost::phoenix::stl::begin, A0>::type = boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::phoenix::detail::tag::function_eval, boost::proto ::argsns_::list2< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost::proto ::argsns_::term<boost::phoenix::stl::begin>, 0l>, boost ::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost::proto ::argsns_::term< boost::range_detail::filtered_range< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost ::proto::argsns_::list2< boost::phoenix::actor< boost::proto::exprns_ ::basic_expr< boost::proto::tagns_::tag ::terminal, boost::proto ::argsns_::term< boost::phoenix ::argument<1> >, 0l> >, boost::phoenix::actor< boost::proto::exprns_ ::basic_expr< boost::proto::tagns_::tag ::terminal, boost::proto ::argsns_::term<int>, 0l> > >, 2l> >, int [5]> >, 0l> >, 2l> > >::type boost::phoenix::begin( const boost::range_detail::filtered_range< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost::proto::argsns_ ::list2< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term< boost::phoenix::argument<1> >, 0l> >, boost ::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost ::proto::argsns_::term<int>, 0l> > >, 2l> >, int [5]>; boost::phoenix::detail::expression::function_eval< boost::phoenix::stl::begin, A0>::type = boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::phoenix::detail::tag::function_eval, boost::proto ::argsns_::list2< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost::proto ::argsns_::term<boost::phoenix::stl::begin>, 0l>, boost ::proto::exprns_::basic_expr< boost::proto::tagns_::tag::terminal, boost::proto ::argsns_::term< boost::range_detail::filtered_range< boost::phoenix::actor< boost::proto::exprns_::basic_expr< boost::proto::tagns_::tag::less, boost ::proto::argsns_::list2< boost::phoenix::actor< boost::proto::exprns_ ::basic_expr< boost::proto::tagns_::tag ::terminal, boost::proto ::argsns_::term< boost::phoenix ::argument<1> >, 0l> >, boost::phoenix::actor< boost::proto::exprns_ ::basic_expr< boost::proto::tagns_::tag ::terminal, boost::proto ::argsns_::term<int>, 0l> > >, 2l> >, int [5]> >, 0l> >, 2l> > &) Thanks, Nate