linker command failed at fastmath installing pycrypto on OSX
Question: I did `pip install pycrypto` (actually wanted to install `fabric` but it
failed at pycrypto) and got the error below. I'm on python 2.7.3. Tried 3.3
too but same error. How do I fix this please?

My clang version:

    
    
    $ clang --version
    Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
    Target: x86_64-apple-darwin11.4.2
    Thread model: posix
    

Error:

    
    
    ...
    
    creating build/lib.macosx-10.7-x86_64-2.7/Crypto/Signature
    
    copying lib/Crypto/Signature/__init__.py -> build/lib.macosx-10.7-x86_64-2.7/Crypto/Signature
    
    copying lib/Crypto/Signature/PKCS1_PSS.py -> build/lib.macosx-10.7-x86_64-2.7/Crypto/Signature
    
    copying lib/Crypto/Signature/PKCS1_v1_5.py -> build/lib.macosx-10.7-x86_64-2.7/Crypto/Signature
    
    running build_ext
    
    running build_configure
    
    building 'Crypto.PublicKey._fastmath' extension
    
    creating build/temp.macosx-10.7-x86_64-2.7
    
    creating build/temp.macosx-10.7-x86_64-2.7/src
    
    cc -fno-strict-aliasing -fno-common -dynamic -I/usr/local/include -Wall -Wstrict-prototypes -std=c99 -O3 -fomit-frame-pointer -Isrc/ -I/usr/include/ -I/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c src/_fastmath.c -o build/temp.macosx-10.7-x86_64-2.7/src/_fastmath.o
    
    src/_fastmath.c:1545:20: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
    
                            else if (result < 0)
    
                                     ~~~~~~ ^ ~
    
    src/_fastmath.c:1621:20: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
    
                            else if (result < 0)
    
                                     ~~~~~~ ^ ~
    
    2 warnings generated.
    
    cc -bundle -undefined dynamic_lookup -L/usr/local/lib build/temp.macosx-10.7-x86_64-2.7/src/_fastmath.o -lgmp -o build/lib.macosx-10.7-x86_64-2.7/Crypto/PublicKey/_fastmath.so
    
    ld: illegal text-relocation to ___gmp_binvert_limb_table in /usr/local/lib/libgmp.a(mp_minv_tab.o) from ___gmpn_divexact_1 in /usr/local/lib/libgmp.a(dive_1.o) for architecture x86_64
    
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    
    error: command 'cc' failed with exit status 1
    
    ----------------------------------------
    
    Command /usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python -c "import setuptools;__file__='/var/folders/_2/fwbd8jjn0mj_y_9w4f31g2nm0000gn/T/pip-build/pycrypto/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/_2/fwbd8jjn0mj_y_9w4f31g2nm0000gn/T/pip-riA3zG-record/install-record.txt --single-version-externally-managed failed with error code 1 in /var/folders/_2/fwbd8jjn0mj_y_9w4f31g2nm0000gn/T/pip-build/pycrypto
    
    Exception information:
    Traceback (most recent call last):
      File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.2.1-py2.7.egg/pip/basecommand.py", line 107, in main
        status = self.run(options, args)
      File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.2.1-py2.7.egg/pip/commands/install.py", line 261, in run
        requirement_set.install(install_options, global_options)
      File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.2.1-py2.7.egg/pip/req.py", line 1166, in install
        requirement.install(install_options, global_options)
      File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.2.1-py2.7.egg/pip/req.py", line 589, in install
        cwd=self.source_dir, filter_stdout=self._filter_install, show_stdout=False)
      File "/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pip-1.2.1-py2.7.egg/pip/util.py", line 612, in call_subprocess
        % (command_desc, proc.returncode, cwd))
    InstallationError: Command /usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python -c "import setuptools;__file__='/var/folders/_2/fwbd8jjn0mj_y_9w4f31g2nm0000gn/T/pip-build/pycrypto/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/_2/fwbd8jjn0mj_y_9w4f31g2nm0000gn/T/pip-riA3zG-record/install-record.txt --single-version-externally-managed failed with error code 1 in /var/folders/_2/fwbd8jjn0mj_y_9w4f31g2nm0000gn/T/pip-build/pycrypto
    


Answer: I was using an HPC version of gcc. So I removed that and reinstalled Command
Line Tools in Xcode. Then I was able to install pycrypto and fabric.

