It’s not a good idea. You end up with two different C runtimes in memory that cannot communicate, and many things will not work properly. If you compile your debug build extension with the non-debug CRT (/MD rather than /MDd) you will lose asserts, but otherwise it will work fine and the quoted code picks the release lib. Or if you like, when you install Python 3.5 or later there are advanced options to install debug symbols and binaries. You can use a proper debug build against the debug binaries (python_d.exe). Cheers, Steve Top-posted from my Windows phone From: Ivan Pozdeev via Python-ideas Sent: Saturday, December 30, 2017 13:01 To: python-ideas@python.org Subject: [Python-ideas] Allow to compile debug extension against releasePython in Windows The Windows version of pyconfig.h has the following construct:     if defined(_DEBUG)            pragma comment(lib,"python37_d.lib")     elif defined(Py_LIMITED_API)            pragma comment(lib,"python3.lib")     else            pragma comment(lib,"python37.lib")     endif /* _DEBUG */ which fails the compilation of a debug version of an extension. Making debugging it... difficult. Perhaps we could define some other constant? I'm not sure whether such compilation is a good idea in general, so asking here at first. -- Regards, Ivan _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/