Invalid unused export warning on 1.75.0-nightly (cd674d617 2023-10-24)

[dignifiedquire]

CI started failing for us, without code changes in this area today with nightly

The code is sth like this

mod keys;
pub use keys::*;

and produces

error: unused import: `keys::*`
  --> iroh-sync/src/lib.rs:44:9
   |
44 | pub use keys::*;
   |         ^^^^^^^
   |
   = note: `-D unused-imports` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(unused_imports)]`

but it should not, given that this is a public export in src/lib.rs.

Version with regression

latest update on 2023-10-24, rust version 1.75.0-nightly (cd674d617 2023-10-24)

Logs

CI logs: https://github.com/n0-computer/iroh/actions/runs/6624632107/job/17994903346?pr=1708

[dignifiedquire]

Okay, I am very confused, now this got triggered on stable as well: https://github.com/n0-computer/iroh/actions/runs/6625039736/job/17995549252

stable-aarch64-apple-darwin unchanged - rustc 1.73.0 (cc66ad468 2023-10-03)

[dignifiedquire]

Can reproduce the warning on my local machine using

cargo +nightly --version
cargo 1.75.0-nightly (d2f6a0485 2023-10-20)

but

cargo --version
cargo 1.73.0 (9c4383fb5 2023-08-26)

does not trigger it

[bvanjoi]

This behavior introduced through #116033.

And I think this behavior is indeed expected because iroh-sync::keys::* has been re-exported in iroh-sync::sync so pub use keys::* is not used: https://github.com/n0-computer/iroh/blob/main/iroh-sync/src/sync.rs#L28

[Teapot4195]

Behavior seems correct, just not very obvious why. Maybe the warning should print out why the symbol might be unused?

[dignifiedquire]

I see, thanks a lot, that was definitely on the confusing side, but glad the compiler catches it now :)

[dignifiedquire]

Behavior seems correct, just not very obvious why. Maybe the warning should print out why the symbol might be unused?

Agreed, I wonder if it could print out a warning about the shadowing of the reexport.