This was a bit confusing for me to read, as it was using an old style of rust that I am not used to
Unfortunately, this lint group isn't on by default, but I think `elided_lifetimes_in_paths` may be on track to be deny-by-default in edition 2021?
Currently, the lifetime elision doc only documents function definitions, but lifetime elision is also allowed in the following other locations:
* `fn` types, such as `fn(&T)`
* `Fn`/`FnMut`/`FnOnce`, such as `Fn(&T)`
* `impl` headers
To demo this up, I made some type aliases for `fn`/`Fn` which you can pass `&T` as a parameter to (to follow the lifetime rules of the surrounding context), and compared what you get with that instead of using `fn`/`Fn` directly, where lifetime elision takes on the rules from `fn`/`Fn`/etc.
I also demoed up an `impl` header that used lifetime elision twice, although the error message in that case is broken (filed https://github.com/rust-lang/rust/issues/87763)
The demo was half for this change description, and half just to make sure I understand Rust -- in particular, I really had to reverse engineer it for `impl` because I wasn't sure, and it didn't seem to be documented anywhere (at least not here!)
https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=f82b280de4b992f225bc32121f333e96
I'm not sure if this is actually desirable. For one thing, the link I used isn't
locked to c++20 exactly. But it is the same page the [std lib](https://doc.rust-lang.org/std/sync/atomic/enum.Ordering.html) links to
so that may be good for something.
I'm also not sure if other references to `C++11` should be updated or removed.
Basically, I feel like _something_ should change here but I'm not really sure what :-\