pub type Foo = foo::Foo causes bad dead_code warnings on enum variants

[lilyball]

The following code triggers dead_code warnings on each enum variant:

pub type Foo = foo::Foo;
pub mod foo {
    pub enum Foo {
        One,
        Two
    }
}

This happens even though the enum is fully public. Commenting put the pub type line gets rid of the warnings.

[dherman]

I ran into a similar issue:

mod tc39 {
    #[derive(Debug, Copy, Eq, PartialEq)]
    pub enum Politics {
        Good,
        Bad,
        Ugly
    }
}

use tc39::Politics::*;

fn main() {
    match Good {
        Good => println!("good!"),
        Bad => println!("bad!"),
        Ugly => println!("ugly!")
    }
}

This warns that Bad and Ugly aren't used.

[sanxiyn]

@kballard's code does not warn any more. @dherman's code does.

[birkenfeld]

@dherman's still does, but isn't that correct? The module is not public, neither is the import. If you make the use tc39::Politics::* a pub use, there is no warning anymore.

[sanxiyn]

This seems to be a case of #19140. Use in pattern doesn't count as use.

[Mark-Simulacrum]

Yes, we don't consider this sort of use a use, since it doesn't construct the value. Closing in favor of #19140.