This fix is __required__ to build a lot of important packages in the python ecosystem, like numpy, pandas, pywin32 and probably a lot more, as most of these important packages have not migrated to setuptools and usually maintain support for multiple python versions.

I know that there is a way to change all the packages to use the canonical approach to compile things, but most of them have a tweaked compiler on top of the msvc9compiler.py compiler. I do not see a change in all the python packages to happen as fast as a small backwards compatible commit in the main cpython code. I see this commit as a fix for the win-arm64 package build and not an "extra" feature.

As I can see it, not adding this fix here will require a split of trees that are going to be used just for this reason.

I will add the fix to setuptools too, but that will not change the above (maintaining separate branches for people who want to use those packages).