Tracking issue for release notes of #130897: library: Compute RUST_EXCEPTION_CLASS from native-endian bytes

[rustbot]

This issue tracks the release notes text for #130897.

Steps

• Proposed text is drafted by PR author (or team) making the noteworthy change.
• Issue is nominated for release team review of clarity for wider audience.
• Release team includes text in release notes/blog posts.

Release notes text

The responsible team for the underlying change should edit this section to replace the automatically generated link with a succinct description of what changed, drawing upon text proposed by the author (either in discussion or through direct editing).

# Compatibility Notes
- [The ABI-level exception class of a Rust panic is now encoded with native-endian bytes,
  so it is legible in hex dumps.](https://github.com/rust-lang/rust/pull/130897)

Tip

Use the previous releases categories to help choose which one(s) to use.
The category will be de-duplicated with all the other ones by the release team.

More than one section can be included if needed.

Release blog section

If the change is notable enough for inclusion in the blog post, the responsible team should add content to this section.
Otherwise leave it empty.

cc @workingjubilee, @thomcc -- origin issue/PR authors and assignees for starting to draft text

[workingjubilee]

Compatibility notes.

I'd probably go with the issue name, ish:

• The ABI-level exception class of a Rust panic is now encoded with native-endian bytes, so it is legible in hex dumps.

Added the relnotes tag on request of @nbdd0121 whomst maintains some code that works with Rust's exception class, as it does an unwinding implementation. However I should note this is an unstable implementation detail of std, so it's not clear to me whether this should indeed be included in relnotes.

[RalfJung]

Rust panics now are encoded

That sounds like something completely different than what the PR does, IMO. It's no about encoding Rust panics as a whole, it's just about which 64bit-identifier we use to mark an unwind as originating from Rust. The term "exception class" should show up, IMO.

But yeah this is not for the blog post I'd say, just for the "compatibility notes" section.

[workingjubilee]

Thank you for catching that! I meant to say something about "exception class" but apparently my intent never reached the keyboard. Fixed.