Better error message for 'is private'

[gilescope]

mod foo {
    use bar::A;
    
    mod bar {
        pub struct A {}
    }
}

use foo::A;

fn main() {}

Produces the error:

error[E0603]: struct `A` is private
 --> src/main.rs:9:10
  |
9 | use foo::A;
  |          ^

playground link

It would be great if the error message said why the pub struct 'A' is private.
For example something like this:

error[E0603]: struct `A` is private because it is not exported by module foo

This would remove the head scratching time as one looks at the definition of the struct and sees the pub visibility modifier.

[gilescope]

(Bonus points for a suggestion that foo::bar::A is public and maybe you meant to use that one.)

[kornelski]

Similar to #42909

[steveklabnik]

Triage:

note: the struct import `A` is defined here...
 --> src/main.rs:2:9
  |
2 |     use bar::A;
  |         ^^^^^^
note: ...and refers to the struct `A` which is defined here
 --> src/main.rs:5:9
  |
5 |         pub struct A {}
  |         ^^^^^^^^^^^^ consider importing it directly

is very similar to

(Bonus points for a suggestion that foo::bar::A is public and maybe you meant to use that one.)

[estebank]

Current output:

error[E0603]: struct import `A` is private
 --> src/main.rs:9:10
  |
9 | use foo::A;
  |          ^ private struct import
  |
note: the struct import `A` is defined here...
 --> src/main.rs:2:9
  |
2 |     use bar::A;
  |         ^^^^^^
note: ...and refers to the struct `A` which is defined here
 --> src/main.rs:5:9
  |
5 |         pub struct A {}
  |         ^^^^^^^^^^^^ you could import this directly