Enforce GCC instead of MSVC on windows

[zehua-jerry-yu]

I am using setuptools to install, and I want to enforce GCC compiler instead of MSVC on windows. I tried some methods mentioned in here, but the setup.cfg method mentioned does not work. I could specify --compiler msvc but if I write --compiler mingw32 it raises several errors: gcc: error: /EHsc: No such file or directory, gcc: error: /bigobj: No such file or directory, gcc: error: /std:c++14: No such file or directory.

Also, I tried the following command (env_csmar is an anaconda virtual environment under my disk F):

D:\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin\gcc.exe -static -shared -std=c++14 -DMS_WIN64 -fPIC "-IF:\...\env_csmar\lib\site-packages\pybind11\include" "-IF:\...\env_csmar\include" "-L F:\...\env_csmar\libs" -c example_cpp.cpp -o example_cpp.o

This works, and the .o file can be imported as a module on my windows. However, it still says it is compiled with MSVC (from #ifdef _MSVC_LANG). Why is this?

A very detailed description of my situation can be found here (link).