Improve spans with use crate::{self}

[SparkyPotato]

Fixes #104276.

The error becomes:

error: crate root imports need to be explicitly named: `use crate as name;`
 --> src/lib.rs.rs:1:13
  |
1 | use crate::{self};
  |             ^^^^

warning: unused import: `self`
 --> src/lib.rs:1:13
  |
1 | use crate::{self};
  |             ^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

[rustbot]

r? @estebank

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[cjgillot]

@SparkyPotato could you add a ui test for this?

[SparkyPotato]

Done!

[cjgillot]

@bors r+

[bors]

📌 Commit c7b2891 has been approved by cjgillot

It is now in the queue for this repository.