@steve.dower
I finally got around to reflecting this in for the scipy toolchain documentation in DOC: update toolchain.rst to reflect windows universal C runtime by h-vetinari · Pull Request #13713 · scipy/scipy · GitHub, and @rgommers voiced concerns about the impact re: potential subtle bugs and the difficulty of debugging them.
As an intermediate step, I opened POC: Build windows with vs2019 by h-vetinari · Pull Request #165 · conda-forge/scipy-feedstock · GitHub, where Isuru from conda-forge/core pointed out that if scipy were to build its windows wheels with vs2019, users would still need to upgrade their UCRT (presumably through the windows update process?), and that this would complicate all static linkages, because then any library linking to (e.g. npymath.lib) would need a linker that’s at least as new.
Since this new input sounds like the opposite of what you said previously, I wanted to kindly ask you for your thoughts on this. Especially as this would put scipy back to square one regarding using newer toolchains until Issue 42380: Build windows binaries with MS VS2019 16.8+ / MSVC 19.28+ - Python tracker is solved (+ 4years until that’s the oldest supported python version), which then means not being able to use C99/C11, etc.
Edit: I unintentionally misrepresented Isuru’s statement; he clarified on the issue:
Note that I didn’t mean to say that UCRT needs to be updated. I mean Visual Studio C++ runtime.