gh-111178: fix USAN failures for partialobject

[picnixz]

Before reviewing this one, I'll add a suppression file with all the incriminating functions. And whenever I make a new PR for fixing USAN failures, I'll just remove the corresponding entries so that we can really check the changes by running the build bot.

• Issue: UBSan: Calling a function through pointer to incorrect function type is undefined behavior #111178

[vstinner]

What's the status of this PR? Why is it a draft?

[picnixz]

What's the status of this PR?

Forgotten :D

Why is it a draft?

I wanted to add the suppression before but since it wouldn't have worked anyway, I can mark it as ready (I'll just check that the warnings for partialobjects indeed disappeared).

[picnixz]

@vstinner Do you want me to add some _PyPartialObject_CAST?

[vstinner]

If you want to fix UBSan issues for partial(), you should patch more methods like: partial_dealloc, partial_repr, partial_traverse, etc.

[vstinner]

@vstinner Do you want me to add some _PyPartialObject_CAST?

I have mixed feelings about these macros :-) You can add a macro which just do the cast and don't check the type, or don't add the macro. As you want.

[picnixz]

If you want to fix UBSan issues for partial(), you should patch more methods like: partial_dealloc, partial_repr, partial_traverse, etc.

Oups, I forgot to do it. I think I only checked the warnings thinking that the rest would be reported. I'll do it tomorrow (hence reconverting into a draft).

[picnixz]

I haven't touched the utilities functions since they are not used as callbacks and shouldn't lead to undefined behaviours (e.g., partial_setvectorcall).

[vstinner]

LGTM

[vstinner]

Merged, thanks.