If you are running:

  • Mac OS X Lion 10.7.4
  • Xcode 4.3.3 installed via the App Store
  • ruby 1.9.3

…and you’ve removed previous versions of the Xcode environment, when you build gems with native extensions, you may see this:

/Users/dpassage/.rvm/rubies/ruby-1.9.3-p125/bin/ruby extconf.rb
creating Makefile

make
compiling autolink.c
make: /usr/bin/gcc-4.2: No such file or directory
make: *** [autolink.o] Error 1

This means you need to upgade your ruby! ruby 1.9.3-p125 contains a patch which hardcodes the gcc version used on OS X as gcc-4.2. The newer version fixes this, and just uses /usr/bin/gcc. As it should.