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Python

Since the official CPython implementation doesn't support building with GCC/Clang on Windows and has its own Windows specific directory layout, we maintain a friendly fork of CPython at https://github.com/msys2-contrib/cpython-mingw/

Some differences/features compared to the official Windows CPython:

  • In an active MSYS2 environment os.sep and os.altsep are switched to make relative paths more compatible with Unix tools that don't understand Windows paths. Outside of an active MSYS2 environment it behaves normally though.
  • sys.path uses the Unix directory layout, see python -m site
  • Virtual environments also work with bash: python -m venv _venv, source _venv/bin/activate and so on.
  • When building against the limited API only defining Py_LIMITED_API isn't enough, you also have to explicitly link against python3 instead of python3.y.

Portability

As long as you don't hardcode/assume platform specific values and paths and always use things like os.sep, do path operations with os.path or pathlib and derive Python installation related paths and configuration from the sysconfig module then your Python code should work just like with the official Windows CPython installation.

If for some reason you still need to detect our fork you can check for it as follows:

import os import sysconfig if os.name == "nt" and sysconfig.get_platform().startswith("mingw"): print("cpython-mingw detected!")

Known issues

  • C extensions are not compatible with the official CPython, which means pip can't use binary wheels from PyPI and packages have to be build when installing them.
  • Some C extensions don't build out of the box since they don't expect non-MSVC on Windows. In some cases we provide patched versions in our repo.
  • Passing --py-limited-api to upstream setuptools does not result in linking with the limited ABI DLL. See the upstream issue. The setuptools package in our repo is patched to fix this.

Changelog

  • 2024-11-09: With the update to Python 3.12, the environment variable setting SETUPTOOLS_USE_DISTUTILS=stdlib will cause distutils import errors because the standard library's distutils module has been removed. If you're still using this workaround, remove the environment variable.
  • 2024-07-01: setuptools now supports building C extensions in MSYS2 since v70.2.0. Previous versions required export SETUPTOOLS_USE_DISTUTILS=stdlib as a workaround.
  • 2023-08-22: The mingw Python now provides the limited ABI DLL (libpython3.dll). Support in upstream setuptools is still missing though.