http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47558
--- Comment #6 from Jack Howarth <howarth at nitro dot med.uc.edu> 2011-02-01 03:55:13 UTC --- We should be very concerned about the fact that on the darwin10 builds of gcc trunk, we don't prefix the same symbols in the FSF gcc's libgcc_s.1.dylib with $ld$hide$os10.4$, $ld$hide$os10.5$ and $ld$hide$os10.6$ as the system libgcc_s.1.dylib . It is entirely uncertain how the darwin linker behaves when only shown... /sw/lib/gcc4.6/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.10) as a linkage since /sw/lib/gcc4.6/lib/libgcc_s.1.dylib contains the same symbols as in /usr/lib/libgcc_s.1.dylib but without these magic prefixes. It is an open question if the stub mechanism is properly engaged in this case. I am trying to getting a clarification from the Apple linker developer on how serious this problem is.