IF YOU NEED XCODE'S COMPILER, THIS WILL BREAK ALL THE THINGS!!!
- Install GCC for OSX.
- The filename of the download for Mountain Lion is listed as GCC-10.7.pkg on the site, but downloads as GCC-10.7-v2.pkg
- If you get a warning that the file can't be opened because it's from an unidentified developer, just control-click on it, and then click open.