Beta no longer compiles code which imports a re-export from the same sub-module from the root

[daboross]

Hi,

I'm not sure if this is a duplicate of another issue, but this is something I ran into in one of my projects. Here's a minimal reproduction:

pub mod objects {
    #[macro_use]
    mod macros {
        macro_rules! reference_wrappers {
            ($name:ident) => {
                pub struct $name(Reference);
            };
            ($($name:ident),* $(,)*) => {
                $(
                    reference_wrappers!($name);
                )*
            };
        }
    }
    mod impls {
        use ConstructionSite;
    }

    reference_wrappers!(ConstructionSite,);

    struct Reference;
}

pub use objects::*;

fn main() {}

This will compile fine on stable 1.28.0, but when run on 1.29.0-beta.4, it errors with the following message:

error[E0432]: unresolved import
  --> src/main.rs:16:13
   |
16 |         use ConstructionSite;
   |             ^^^^^^^^^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0432`.
error: Could not compile `playground`.

To learn more, run the command again with --verbose.

I can't find anything obviously wrong with the code that would cause this. This seems to me to be 100% correct Rust which the compiler is rejecting?

Stable playground which works: https://play.rust-lang.org/?gist=4931737787539855373990990044faa7&version=stable&mode=debug&edition=2015

Beta playground which does not: https://play.rust-lang.org/?gist=4931737787539855373990990044faa7&version=beta&mode=debug&edition=2015

[petrochenkov]

Looks similar to #53140

[daboross]

Ah, thanks for finding that! I was a bit to fixated on the macro and missed that this also fails:

pub mod objects {
    mod impls {
        use ConstructionSite;
    }

    pub struct ConstructionSite(Reference);

    struct Reference;
}

pub use objects::*;

fn main() {}

Closing in favor of #53140.