The compiler failed to generate an executable file. (RuntimeError)

Question

I recently upgraded to OS Mountain Lion. A project I\'m working on requires gem sys-proctable as a dependency, but when I run bundle install I get:

Answer 1

Be sure to open XCode after updates. I found that I had to open it and accept the new license agreement after a recent update of XCode via the App Store. Otherwise I received the "The compiler failed to generate an executable file. (RuntimeError) You have to install development tools first."