Add `unsafe_precondition_assert!`

[ojeda]

See https://lore.kernel.org/rust-for-linux/CANiq72mi47p0jVoXXq1d1G+7PnHi7ngs6zTS084igfZZzzNGBw@mail.gmail.com/.

Like #1159, but for unsafe_precondition_assert!.

The name mimics other {kind}_assert!s like debug_assert!, as well as core's ub-checks one (assert_unsafe_precondition!).

Please double check if there are already asserts out there (or perhaps even new ones) that could make use of it, and transform (or add) them in a second patch etc.

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This requires submitting a proper patch to the LKML and the Rust for Linux mailing list. Please recall to test your changes (including generating the documentation if changed, running the Rust doctests if changed, etc.), to use a proper title for the commit, to sign your commit under the Developer's Certificate of Origin and to add a Suggested-by: tag, and a Link: tag to this issue. Please see https://docs.kernel.org/process/submitting-patches.html and https://rust-for-linux.com/contributing for details.

[hz2]

hi id like to take this on

[ojeda]

Sure, thanks, please go ahead!

(For other readers/future issues: no need to mention it -- you all can just send the patch! :)

[hz2]

thank you!

for future reference, is there a way to check if a issue is already being worked on?

[ojeda]

You're welcome!

Unless someone posts here, not really (one may want to search Lore for the issue link, though, e.g. https://lore.kernel.org/rust-for-linux/?q=https%3A%2F%2Fgithub.com%2FRust-for-Linux%2Flinux%2Fissues%2F1126.

So if you expect to take long to send it, it may be a good idea to still post a note here (but of course there is no need to ask for permission to start, if that makes sense).

[BennoLossin]

@ojeda fyi this issue is both labeled easy and medium, is that intentional? (#1159 also has both labels)

[ojeda]

Yeah, I meant it as "it could be either", or perhaps "in-between", depending on the person and/or the discussion in the list, so that people would find it if searching for either of the tags. I did it in others too, I think. But if it is confusing, we can remove it.