Hi, This is my first post here, so please do not hesitate in letting me know if this is not the correct forum for my question. I am running our front end through the regression tests for boost 1.33.1. Using the same compiler configuration we have been able to get through the regression for 1.32.0. In 1.33.1, we are producing an error that is_convertible is not a type on line 95 of boost/type_traits/is_enum.hpp. We get this error when running tests in libs/filesystem/test. From what I can tell, the problem is that is_convertible requires is_enum be defined which in turn requires is_convertible to be defined. The include path for the particular test has: boost/filesystem/exception.hpp-> /boost/filesystem/path.hpp /boost/filesystem/path.hpp-> boost/iterator/iterator_facade.hpp boost/iterator/iterator_facade.hpp-> boost/iterator/interoperable.hpp boost/iterator/interoperable.hpp-> boost/type_traits/is_convertible.hpp [This include is conditional on BOOST_NO_IS_ABSTRACT] boost/type_traits/is_convertible.hpp-> boost/type_traits/is_abstract.hpp boost/type_traits/is_abstract.hpp-> boost/type_traits/is_class.hpp boost/type_traits/is_class.hpp-> boost/type_traits/is_scalar.hpp boost/type_traits/is_scalar.hpp-> boost/type_traits/is_enum.hpp Setting BOOST_NO_IS_ABSTRACT does solve the issue, however I don't think it is the *best* solution. Any help appreciated. Regards, Richard