On OS X 10.8 or 10.9 when using Xcode 5 and attempting to build an extension module using a universal Python that includes a PPC architecture (such as from one of the python.org 32-bit-only installers), the extension module build can fail with numerous compiler errors.  Recent python.org 32-bit-only installers attempt to remove unavailable PPC architectures when building extension modules.  Unfortunately, due to changes between Xcode 4 and Xcode 5, the test in Distutils does not work with Xcode 5 compilers.

The problem affects the current OS X 32-bit-only python.org installers for Python 3.3.2 and 2.7.5.  It is not a problem for OS X 64-bit/32-bit installers for 10.6+.

A workaround for the problem is to override the Distutils defaults by setting the ARCHFLAGS environment variable to the desired architectures, for example:

ARCHFLAGS="-arch i386" /usr/local/bin/python2.7 -m pip install ...