Mileage may vary on this one, but after upgrading to Yosemite, I encountered two issues with brew.
The first was with gcc47. After running, "brew upgrade". It got stuck on the gcc47 formula, which error'd with:
==> Upgrading gcc47 gcc47: OS X Mavericks or older is required for stable. Use `brew install devel or --HEAD` for newer. Error: An unsatisfied requirement failed this build.
I decided it was better to move to gcc48 than to bother trying to get gcc47 working. To do that, just install gcc48 and remove gcc47 with:
➜ ~ brew install gcc48 ➜ ~ brew uninstall gcc47
There is an open issue with brew for that one. (https://github.com/Homebrew/homebrew/issues/33422)That fixed that. Then, I ran into an issue with subversion, which relied on serf. The failed to compile with:
#include <apr_pools .h=""> ^ 1 error generated. scons: *** [context.o] Error 1 scons: building terminated because of errors.
But you can get around the issue by installing the command line tools for xcode with:
➜ xcode-select --install
If you run into the same issues, hopefully that fixes you.