There are two implementations of boost::result_of: a TR1-style implementation and a decltype-based implementation. While the TR1-style implementation has a public interface `boost::tr1_result_of`, decltype-based one doesn't have a public interface. By defining BOOST_RESULT_OF_USE_DECLTYPE, boost::result_of use decltype-based implementation. But this is not always a viable solution, since this breaks some Boost libraries. So how about adding `boost::cxx11_result_of` as public interface of the decltype-based implementation? Attached a patch to add `boost::cxx11_result_of`. (This patch also changes the name of `cpp0x_result_of_impl` to `cxx11_result_of_impl` to reflect the recent discussion on the cpp/cxx naming.) P.S. Is it worth trying to use this `boost::cxx11_result_of` in `boost::transform_iterator` code on trunk? Regards, Michel