JuliaLang/julia — pull request #976 by ViralBShah (2012-06-26 17:27:22+00:00)
Title: Use clang as default compiler on OS X

I am planning to change to clang as the default compiler on OS X. Apple has not been shipping gcc higher than 4.2 for a while now. OpenBLAS 0.2.0 (yet to release), which includes sandybridge support, does not compile with the old gcc on OS X.

It seems like the right time to bite the bullet and move to clang. This requires clang 3.1, which means updating to the latest Xcode and command line utilities. Presumably, this should also make it possible to enable AVX instructions in FFTW as well.

On Snow Leopard, one can continue to use GCC with USEGCC=1 USECLANG=0. On Lion, with gcc 4.7 and higher, I believe things should work fine too.

`make test` does not break with this change.