It won't work in our case because the gcc 4.9 build we have references it's own c rts lib, which is 4.9 specific, and is notably different than what is on a stock Mac
Imagine if we were to ship a libHSrts.a, compiled against the gcc 4.9 libc (and it's includes). Now a user without gcc 4.9 on thier system, installs that bindist. And when they compile code that references libc, it'll compile against the system libc (and it's includes). If tha code is paired with Haskell code (or *is* Haskell code via the FFI), and is then linked with libHSrts.a from the bindist.... now we have an executable that has parts compiled against two different libc-s. This won't work unless the two libcs (and their includes) are ABI compatible.... which I don't know if it is between gcc's 4.9 libc, and the libc Apple ships for it's systems.