Windows on ARM should install to (Arm) directory

[jaraco]

When installing Python 3.13 for ARM on Windows using administrative privileges (for all users), it defaults to the C:\Program Files\Python313-arm64 directory. That means that the installation directories are inconsistent with how they're installed for other architectures, which use the architecture-specific folder for installation.

On Windows for ARM, Microsoft has chosen to still give prominence to AMD64, so the "Program Files" directory belongs to AMD64 programs, and there's a separate "Program Files (Arm)" (aka %PROGRAMFILES(ARM)%) directory for the native architecture. It's sort-of too bad that "Program Files" wasn't used for the native architecture, but that's the choice the platform has made.

I propose that the Windows for ARM installer should install to %PROGRAMFILES(ARM)% directory by default when installing for all users, and use the same naming scheme for "Python313".

[zooba]

Afraid not, the %PROGRAMFILES(ARM)% is intended for Arm32 apps. Apps native to the platform should be in %PROGRAMFILES%, and for some unknown reason there is no %PROGRAMFILES(X64)% as would be expected. (Unfortunately, I can't find a public reference for this, apart from a few credible sounding posts including #90900 where we changed back from installing to the wrong location.)

In any case, this is pending a PEP 773 result, which will take upstream out of the per-machine world entirely. Other distributors can choose where they want to install to, but I'm personally persuaded that %PROGRAMFILES% is correct and Python313-arm64 is an unfortunate wart that is viable for our current installer. (If PEP 773 is rejected then I'll still look to change the current installers, just in a way that doesn't impact user's workflows so dramatically.)

[jaraco]

the %PROGRAMFILES(ARM)% is intended for Arm32 apps

Thanks for the clarification. So many variables! Glad to hear that %programfiles% is preferable in most cases.

[zooba]

FWIW, I fired up a Windows on ARM64 24H2 (latest update) machine last week and there's no Program Files (Arm) directory at all. So I guess the last of the compatibility bits are gone.