Okay. If someone can point me in the right direction, I'm willing to try and fix it up myself. I tried digging through the compiler selection code but couldn't figure out what the problem was.

However, regardless of when using ```brew install ghc --use-gcc```, the ```--with-gcc=gcc-4.2``` is still necessary during configuration of the bootstrap binary and the main sources.

The problem with that of course is that ```fails_with :clang``` allows for other options that ```apple-gcc42```, so that needs to be taken into account somehow.