Hello everybody, I've a problem with the boost fusion library. I try to convert a fusion set into a map using the transform algorithm. Here is a example: typedef typename boost::fusion::result_of::as_map< typename boost::fusion::result_of::transform<BoundMembers, map_name_to_member>::type

::type Content;

where BoundMembers is a boost::fusion::set and map_name_to_member is defined as: struct map_name_to_member { template <typename T> struct result; template <class F, typename T> struct result<F(T)> { typedef boost::fusion::pair<typename T::Name, typename T::Member> type; }; }; With boost 1.56 and gcc 4.8.1 I get the following compilation error: include/boost/fusion/iterator/key_of.hpp:36:16: error: invalid use of incomplete type ‘struct boost::fusion::extension::key_of_impl<boost::fusion::transform_view_iterator_tag>’ struct key_of ^ include/boost/fusion/iterator/key_of.hpp:21:16: error: declaration of ‘struct boost::fusion::extension::key_of_impl<boost::fusion::transform_view_iterator_tag>’ struct key_of_impl; However, this code used to work with Boost 1.48. I found a workaround to fix this, by converting the result of transform to a fusion list before coverting it to a map, i.e.: typedef typename boost::fusion::result_of::as_map< typename boost::fusion::result_of::as_list< typename boost::fusion::result_of::transform<BoundMembers, internal::map_name_to_member>::type

::type ::type Content;

Am I doing something wrong or is this intended behavior? Thanks for your support. Best regards, Christian Kerl