For reasons outside the scope of this discussion, we're experimenting with statically linking libgcc.a and libgcc_eh.a into dynamically linked applications which depend on libc but no other dynamic libraries. To make this work, libc needs to access a few functions for stack unwinding inside pthread_cancel. With suitable modifications, everything works, except for one problem: libgcc_eh.a is compiled with -fvisibility=hidden.
Now, I can put together a hack in our local source tree to remove this ... but why is this the case at all? It might make sense for libgcc_s.so, but that's compiled with default visibility (and the set of explicitly visible symbols is broken)? The only other use case I can think of is for shared libraries which (for some reason) want to embed private copies of these libraries, but on x86_64, libgcc*.a get compiled by default without -fPIC, so that doesn't even work. So ... is there a valid reason for this, or is this just an accident of history? AFICT, this behavior dates back to 2007 as of r120429 (http://gcc.gnu.org/viewcvs/trunk/libgcc/static-object.mk?view=markup&pathrev=120429). If no one knows a valid reason for this, I'll submit a patch to remove it from trunk. Otherwise, I'll just modify it locally. Thanks, Ollie
