./mach build shows a warning when running on Python 3.10, and per searchfox I believe it's not only mach build. See also https://www.python.org/dev/peps/pep-0632/.

The severity field is not set for this bug.
:mhentges, could you have a look please?

For more information, please visit auto_nag documentation.

The severity field is not set for this bug.
:mhentges, could you have a look please?

For more information, please visit auto_nag documentation.

Those who need to parse the output of Mach output can hide Python warning output with the PYTHONWARNINGS environment variable.
E.g.:

PYTHONWARNINGS=ignore ./mach <command>

This is a great bug for future contributors!
We need to adjust all usages of distutils to be ported to something that's still maintained.
A couple notes:

• We don't need to port anything in third_party/python, or testing/web-platform/tests/tools/third_party
• There's some helpful distutils porting docs here
• Let's break down work here by component (mozbuild, mozrelease, mozperftest, etc), creating "sub-bugs" of this meta bug for each one.
• It looks like the majority of changes will be from distutils.version.LooseVersion to packaging.version.Version, and from distutils.spawn.find_executable to shutil.which

testing/web-platform/tests/tools/third_party

Still will be good to have 😉 (but https://github.com/web-platform-tests/wpt is the better place to do it I guess)

Still will be good to have 😉

True, but those will be solved by updating those vendored dependencies - we shouldn't patch distutils out of them, because then we're soft-forking the 3rd-party code, which I don't think we want :)

Things in WPT should be automatically synced back to the upstream by wpt-sync bot, so I think that shouldn't be problematic.

Oh actually scratch that, it's third_party in WPT!