Interesting, thanks for the links! I'm curious as to how many of the apparent issues are attributable to lifetime extension specifically as opposed to something else like async-related deadlocks as mentioned in the parent to the first linked comment (which I feel I've heard much more about), especially after the Rust 2024 changes.

That being said, after a bit more searching I found this 2023 blog from one of the Rust devs [0] which supports the "widespread" description at the time:

> One very common problem is deadlocks (or panics, for ref-cell) when mutex locks occur in a match scrutinee

so I think we can chalk this up to me being insufficiently well-read. I think it would be interesting to see to what extent the Rust 2024 changes alleviated the problem since it only changed if let, but I haven't found that information (yet).

There's also this related work [1], but I think the scope of that is rather larger.

> Interestingly, Mojo might avoid some or all of that, by having some destructors be implicit, and some destructors be explicit, [] , requiring users to write the destructors manually.

There's some relevant exploration being done in Rust that in principle could enable linear types [2], though obviously it remains to be seen to what extent this work will pan out.

[0]: https://smallcultfollowing.com/babysteps/blog/2023/03/15/tem...

[1]: https://blog.m-ou.se/super-let/

[2]: https://github.com/rust-lang/goals/blob/main/src/2026/move-t...