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 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 #include 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_::termboost::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_::termboost::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