When using clang with -fno-rtti, the use of `typeid` results in either compile-time errors or run-time errors. But Boost.Config did not define BOOST_NO_TYPEID for that case. So, for example, including any client header of BOOST_SP_TYPEID produced compiler errors on clang trunk with -fno-rtti. This was fixed in r78510 about a week ago: (http://svn.boost.org/trac/boost/changeset/78510) -#if !__has_feature(cxx_rtti) +#if !__has_feature(cxx_rtti) && !defined(BOOST_NO_RTTI) # define BOOST_NO_RTTI #endif +#if !__has_feature(cxx_rtti) && !defined(BOOST_NO_TYPEID) +# define BOOST_NO_TYPEID +#endif If Boost would like to enhance the support of -fno-rtti on clang, it would be good to merge the fix into the release branch. I ran the test runner (clang trunk with -fno-rtti) for unpatched release branch and patched release branch. There was no regression and more than 1000 test results got improved. Regards, Michel