Trait re-exports fail due to privacy of containing module

[Ryman]

This was working previously before rustc 0.13.0-nightly (3d2cf6063 2014-10-22 00:22:04 +0000).

If this is an intended change, we should probably give the error where the re-export is defined and not on use of the trait.

use foo::Bar;

mod foo {
    pub use self::bar::Bar;

    mod bar {
        pub trait Bar {
            fn call(&self) -> bool;
        }
    }
}

impl foo::Bar for uint {
    fn call(&self) -> bool {
        true
    }
}

fn main() {
    println!("{}", 0u.call())
    //^~ ERROR source trait is inaccessible
}

[jansegre]

I've noticed this too while compiling nphysics, I've narrowed it to http://is.gd/X0EHDP

The error is

<anon>:22:5: 22:13 error: source trait is inaccessible
<anon>:22     b.boom();
              ^~~~~~~~
<anon>:22:5: 22:13 note: module `bar` is private
<anon>:22     b.boom();
              ^~~~~~~~
error: aborting due to previous error

I'm using rustc 0.13.0-nightly (f03745244 2014-10-26 16:42:33 +0000).

[zargony]

I'm facing the same problem for quite some time now (currently rustc 1.0.0-nightly (29bd9a0 2015-01-20 23:03:09 +0000)). Is this a bug or is it intended behavior?

[steveklabnik]

@nikomatsakis is this expected?

[Syntaf]

Just ran into this bug in my code, would love to see a fix for this!

[zargony]

Im also still running into this from time to time (rustc 1.3.0). I'd love to see it fixed or clarified whether this is intended or a bug.

[AndiDog]

I also have this with rustc nightly (from PPA: "201510280406e0e2627wily")

[nikomatsakis]

@steveklabnik I think this is a bug, actually. @nrc @alexcrichton do you agree?

[nikomatsakis]

@steveklabnik yes I realize I'm responding to a comment from Jan 28 :) a bit late, I know

[ghost]

@nikomatsakis this was "fixed" by #28504 but reverted by #29325 due to a regression.

Personally, I think that the correct fix for the regression should be to make pub trait Pub: Priv a privacy error, but as far as I can tell, it's not easy to implement this currently, and it's likely to cause further regressions. Trait privacy is hard :(

[steveklabnik]

@nikomatsakis better late than never ❤️

[alexcrichton]

@nikomatsakis yeah this looks like a bug to me, and I think @eljay is right in that #28504 is probably the right fix if we deal with trait Pub: Priv, which I think is the cause of some other visibility/privacy bug around here...

[sgrif]

This can be simplified even further to: http://is.gd/QG9LGU. Also an additional note, this only affects usage in the same crate. Other crates are able to use the re-exports fine.

[LukasKalbertodt]

Still a bug in 1.6 😢

[sorpaas]

+1

[gbersac]

still a bug in cargo 0.8.0-nightly (28a0cbb 2016-01-17)

[tomaka]

For those who may fall on this issue, it can be bypassed by using the UFCS syntax: TraitName::method(&trait_implementor, params...).

For example http://is.gd/QG9LGU becomes http://is.gd/zYo5Qm