http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60821
a.h.jaffe at gmail dot com changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |UNCONFIRMED Resolution|INVALID |--- --- Comment #2 from a.h.jaffe at gmail dot com --- @Marek I don't think that's right, or at least the behaviour doesn't make sense: http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/Darwin-Options.html#Darwin-Options "Apple's GCC on Darwin does create “fat” files if multiple -arch options are used; it does so by running the compiler or linker multiple times and joining the results together with lipo." And in any event, note that either -arch i386 or -arch x86_64 work *separately*!