While working on updating Boost.Config for msvc-15.5 I've managed to break the test case for boost_no_cxx17_iterator_traits (both GCC and msvc agree on this) but can't see what's wrong :( The change is this one: https://github.com/boostorg/config/commit/305f5a58ef879037b0fd9fdaa8e05615c1... which removes use of std::iterator as a base class. Anyone any ideas? Many thanks, John. --- This email has been checked for viruses by AVG. http://www.avg.com