Martin-Kous-MacBook-Pro:~ martinkou$ sudo easy_install -U Cython
Searching for Cython
Best match: Cython 0.14.1
Running Cython-0.14.1/setup.py -q bdist_egg --dist-dir /tmp/easy_install-5NQPRk/Cython-0.14.1/egg-dist-tmp-gOLK4r
warning: manifest_maker: MANIFEST.in, line 19: 'recursive-include' expects <dir> %lt;pattern1%gt; %lt;pattern2%gt; ...
/usr/libexec/gcc/powerpc-apple-darwin10/4.2.1/as: assembler (/usr/bin/../libexec/gcc/darwin/ppc/as or /usr/bin/../local/libexec/gcc/darwin/ppc/as) for architecture ppc not installed
Installed assemblers are:
/usr/bin/../libexec/gcc/darwin/x86_64/as for architecture x86_64
/usr/bin/../libexec/gcc/darwin/i386/as for architecture i386
/tmp/easy_install-5NQPRk/Cython-0.14.1/Cython/Plex/Scanners.c:6694: fatal error: error writing to -: Broken pipe
lipo: can't open input file: /var/tmp//ccAtkL0J.out (No such file or directory)
error: Setup script exited with error: command 'gcc-4.2' failed with exit status 1
This error pops up for a lot of build scripts besides Python distutil's - Perl modules like ImageMagik are also failing to build on OSX after Xcode4 is installed. The reason for this is Apple has removed the PPC assembler for OSX platforms in Xcode4, yet a lot of existing build scripts for OSX are building universal binaries.
There're quite a few solutions on the Internet, but the cleanest solution I've found so far, is the second solution (as of today) in this Stack Overflow page.
So it turns out Apple has still left a PPC assembler in the iOS platform files for Xcode 4. All you need to do is to make 2 sym links at the appropriate place and it'll work.
$ sudo ln -s /Developer/Platforms/iPhoneOS.platform/Developer/usr/libexec/gcc/darwin/ppc /Developer/usr/libexec/gcc/darwin
$ sudo ln -s /Developer/Platforms/iPhoneOS.platform/Developer/usr/libexec/gcc/darwin/ppc /usr/libexec/gcc/darwin