markusn/homebrew — comment on commit d2cb260b3400cb21a4b07307bdfdcbb268ee61b4
File: Library/Formula/gmp.rb line 25
By mistydemeo:

Xcode 4.0/4.1 users on Lion still have gcc-4.2. Since this is a compiler issue, it could be written as `unless xcode_version >= 4.2` or ```unless File.exist? `which gcc-4.2`.chomp```