http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55061
--- Comment #17 from Ian Lance Taylor <ian at airs dot com> 2012-10-25 17:41:26 UTC --- Thanks for attaching the config.log. The config.log suggests that this program: int main () { return _Unwind_GetIPInfo (); } both compiles and links when using GCC 4.0.1 on Darwin. That would be a surprising result, as it does not link when using the FSF GCC 4.0.1: _Unwind_GetIPInfo is undefined. Apparently with GCC 4.0.1 on Darwin _Unwind_GetIPInfo is defined somewhere. Can you verify that? If that is correct, then the configure script needs to check not only that _Unwind_GetIPInfo is available at link time, but also that it is declared in unwind.h.