Thanks for explaining.

> a) NoneType object is not iterable. If the function don't return empty list
> later distutil will fail

Possible fix: self.dll_libraries = get_msvcr() or []

> method for detection of a msvc runtime is not correct. If the method
> return a library GCC will link to two c-runtimes. Also some function
> dearation are not visible if is not specified appropriate
> preprocessor directive.

Can you propose fixes for those?  Also, how to test it?

> So I could not found reason this method to exist .

“Include the appropriate MSVC runtime library if Python was built with MSVC 7.0 or later.”