Compiling Native Extensions under Xcode 5.1

Trying my hand of late with python and ruby and other bits and pieces but found myself hitting a lot of clang compiler issues when trying to install ruby gems etc on my mac, specifically this sort of thing:

compiling generator.c
linking shared-object json/ext/generator.bundle
clang: error: unknown argument: '-multiply_definedsuppress' [-Wunused-command-line-argument-hard-error-in-future]
clang: note: this will be a hard error (cannot be downgraded to a warning) in the future
make: *** [generator.bundle] Error 1

Luckily after some googling manbolo.com to the rescue, Xcode 5.1 it appears has changed something from a warning to an error as explained in more detail on the blog post here.

Anyway whack in an

export ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future

and you should be right next time you try to

gem install pg

or of course you may need to do this if your using sudo

sudo ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install helios

Hope this helps you too.