[Distutils] Compiling Cython on Windows runs into link problems because of directories containing spaces

Almar Klein almar.klein at gmail.com
Thu Jan 5 11:49:24 CET 2012


I have a problem with compiling Cython code on Windows. I think this is a
bug in distutils which is easy to solve. I have reproduced this on Python
2.6 and Python 3.2 (32 bit).

The problem occurs with the native msvc compiler. Using gcc works fine. And
I prefer using gcc, but sometimes you just need msvc :/

The problem is that the command to link the libraries does not put double
quotes around paths that have spaces in them. Unfortunately, the path where
many users have Python installed have spaces in it (e.g. c:/program
files/python26). Small example: */LIBPATH:C:\Program Files
(x86)\python32\libs*. Oh, and the include_dirs DO have double quotes around

The problem is easily solved (I confirmed this) by changing
msvc9compiler.py and msvccompiler.py:

def library_dir_option(self, dir):  # OLD VERSION

     return "/LIBPATH:" + dir

def library_dir_option(self, dir): # FIXED VERSION

    if ' ' in dir and not dir.startswith('"'):

        dir = '"%s"' % dir

    return "/LIBPATH:" + dir

===== Below follows a minimal example =====

===== test_.pyx
def foo():


===== setup.py

import os, sys

from Cython.Distutils import build_ext

from distutils.core import setup

from distutils.extension import Extension

from numpy.distutils.misc_util import get_numpy_include_dirs

# Ugly hack so I can run setup.py in my IDE

sys.argv = ['setup.py', 'build_ext', '--inplace']

# Init include dirs

include_dirs = ['.']


# Creat Extensions

ext_modules = [

     Extension('test_', ['test_.pyx'],




# Compile


    cmdclass = {'build_ext': build_ext},

    ext_modules = ext_modules,


print('Successfully compiled cython file: test_')

===== output when running setup.py

running build_ext

No module named msvccompiler in numpy.distutils; trying from distutils

cythoning test_.pyx to test_.c

building 'test_' extension

C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\cl.exe /c /nologo
/Ox /MD /W3 /GS- /DNDEBUG -I. -I"C:\Program Files
(x86)\python32\lib\site-packages\numpy\core\include" -I"C:\Program Files
(x86)\python32\include" -I"C:\Program Files (x86)\python32\PC" /Tctest_.c

Found executable C:\Program Files (x86)\Microsoft Visual Studio

C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\link.exe /DLL
/nologo /INCREMENTAL:NO */LIBPATH:C:\Program Files (x86)\python32\libs
/LIBPATH:C:\Program Files (x86)\python32\PCbuild* /EXPORT:PyInit_test_

Found executable C:\Program Files (x86)\Microsoft Visual Studio

LINK : fatal error LNK1181: cannot open input file 'Files.obj'
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