Appendix: Installing MinGW on Windows

  1. Download the MinGW installer from http://www.mingw.org/wiki/HOWTO_Install_the_MinGW_GCC_Compiler_Suite. (As of this writing, the download link is a bit difficult to find; it’s under “About” in the menu on the left-hand side). You want the file entitled “Automated MinGW Installer” (currently version 5.1.4).

  2. Run it and install MinGW. Only the basic package is strictly needed for Cython, although you might want to grab at least the C++ compiler as well.

  3. You need to set up Windows’ “PATH” environment variable so that includes e.g. “c:\mingw\bin” (if you installed MinGW to “c:\mingw”). The following web-page describes the procedure in Windows XP (the Vista procedure is similar): https://support.microsoft.com/kb/310519

  4. Finally, tell Python to use MinGW as the default compiler (otherwise it will try for Visual C). If Python is installed to “c:\Python27”, create a file named “c:\Python27\Lib\distutils\distutils.cfg” containing:

    [build]
    compiler = mingw32
    

The [WinInst] wiki page contains updated information about this procedure. Any contributions towards making the Windows install process smoother is welcomed; it is an unfortunate fact that none of the regular Cython developers have convenient access to Windows.

Python 3.8+

Since Python 3.8, the search paths of DLL dependencies has been reset. (changelog)

Only the system paths, the directory containing the DLL or PYD file are searched for load-time dependencies. Instead, a new function os.add_dll_directory() was added to supply additional search paths. But such a runtime update is not applicable in all situations.

Unlike MSVC, MinGW has its owned standard libraries such as libstdc++-6.dll, which are not placed in the system path (such as C:\Windows\System32). For a C++ example, you can check the dependencies by MSVC tool dumpbin:

> dumpbin /dependents my_gnu_extension.cp38-win_amd64.pyd
...
Dump of file my_gnu_extension.cp38-win_amd64.pyd

File Type: DLL

  Image has the following dependencies:

      python38.dll
      KERNEL32.dll
      msvcrt.dll
      libgcc_s_seh-1.dll
      libstdc++-6.dll
      ...

These standard libraries can be embedded via static linking, by adding the following options to the linker:

-static-libgcc -static-libstdc++ -Wl,-Bstatic,--whole-archive -lwinpthread -Wl,--no-whole-archive

In setup.py, a cross platform config can be added through extending build_ext class:

from setuptools import setup
from setuptools.command.build_ext import build_ext

link_args = ['-static-libgcc',
             '-static-libstdc++',
             '-Wl,-Bstatic,--whole-archive',
             '-lwinpthread',
             '-Wl,--no-whole-archive']

...  # Add extensions

class Build(build_ext):
    def build_extensions(self):
        if self.compiler.compiler_type == 'mingw32':
            for e in self.extensions:
                e.extra_link_args = link_args
        super(Build, self).build_extensions()

setup(
    ...
    cmdclass={'build_ext': Build},
    ...
)
[WinInst]https://github.com/cython/cython/wiki/CythonExtensionsOnWindows