Add pixi definitions for building with the address sanitizer

[FFY00]

Feature or enhancement

Proposal:

At the moment, it's fairly painful to test downstream projects with the address sanitizer. We need to compile CPython and the whole dependency tree with the ASAN support, and the environment is pretty fragile.

While working on this for NumPy and SciPy, we found that using pixi's pixi-build feature makes this particular job extremely easier. On account of this, it would be extremely helpful to have pixi definitions directly in the CPython upstream, as that would allow us to test against arbitrary versions/commits of CPython. Otherwise, we would need to have these definitions in a 3rd party repo, and manually bump versions there.

Since CPython's build and install process on POSIX, as well as its dependencies, are so stable, the pixi definitions shouldn't need much maintenance.

IMO it would be extremely helpful to host the definitions in this repository in a best-effort maintenance capacity. The NumPy and SciPy downstreams would be immediate users (numpy/numpy#30381, scipy/scipy#24066).

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-142466: Pixi package definitions for downstream use #142469

[hugovk]

See also python/devguide#1669, cc @lysnikolaou.

[FFY00]

Ah, I missed that!

[lucascolley]

let me open a PR with what we have right now, it is far from perfect but hopefully will make it clear to cpython devs what the "best-effort maintenance" would look like