Suggestion to fix clashing trait and generic names is incorrect when desired trait comes from module

[schuelermine]

Code

use crate::a::B;

mod a {
    pub trait B {}
}

struct C<B: B>(B);

Current output

error[E0404]: expected trait, found type parameter `B`
 --> src/lib.rs:7:13
  |
1 | use crate::a::B;
  |               - you might have meant to refer to this trait
...
7 | struct C<B: B>(B);
  |          -  ^ not a trait
  |          |
  |          found this type parameter
  |
help: consider importing this trait instead
  |
1 | use crate::a::B;
  |

Desired output

error[E0404]: expected trait, found type parameter `B`
 --> src/lib.rs:7:13
  |
1 | use crate::a::B;
  |               - you might have meant to refer to this trait
...
7 | struct C<B: B>(B);
  |          -  ^ not a trait
  |          |
  |          found this type parameter
  |

Rationale and extra context

The import is already there. Ideally it should tell you that the import is being shadowed by the generic, but barring that, it definitely shouldn’t suggest adding a useless line of code that already exists and only creates more errors.

Other cases

No response

Anything else?

This happens on stable and nightly.

[fmease]

The desired diagnostic should probably suggest fully qualifying the trait:

- struct C<B: B>(B);
+ struct C<B: crate::a::B>(B);

Technically speaking, in this specific case (where we aren't inside of a function but in a module), it could instead suggest self::B in order to pick up the otherwise unused import use crate::a::B; at the top of the file but that might be a bit esoteric. 😅

[chenyukang]

seems the label you might have meant to refer to this trait is clear enough to point out the issue 😅