rustc should suggest a cast from anonymous function type to function pointer

[tobx]

I have been told in Discord that:

"rustc should be able to see that one is an anonymous fn type and the other a fn pointer with the same call signature"

and that I should open an issue.

Given the following code:

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=b35796ef8b42be226dbba7c213fbd348

The current output is:

error[E0308]: mismatched types
  --> src/lib.rs:21:16
   |
21 |         Self { entries }
   |                ^^^^^^^ expected fn pointer, found fn item
   |
   = note: expected struct `Filter<_, for<'r> fn(&'r Result<walkdir::DirEntry, walkdir::Error>) -> _>`
              found struct `Filter<_, for<'r> fn(&'r Result<walkdir::DirEntry, walkdir::Error>) -> _ {note_filter}>`

Ideally the output should add a note, something like:

Try to cast: `note_filter as MyFilter`

[camelid]

Hmm, it kind of feels like rustc should be performing this cast automatically, though I guess that'd be a larger (and potentially difficult) language change.