@Amanieu Are you going to write an RFC? What can we do to help push this forward?
There is a PR for using the parking_lot code inside of libstd now: https://github.com/rust-lang/rust/pull/56410
If/when this PR is adopted, the Rust cheat sheet will need to be updated for
Mutex<T>, since the new parking_lot code does not have a
poison field. That would also be a good opportunity to add the missing
RwLock<T> to the cheat sheet.
Even with that PR,
Mutex will remain backwards-compatible and hence still have
poison. It will just use the
parking_lot machinery for implementing mutual exclusion, instead of leaving that to OS primitives.
I would absolutely love to update the cheat sheet if a consequence of this work is that the Box is removed. My understanding is that the Box is primarily to ensure that the OS primitive is not moved, and with parking_lot that goes away.