#[deriving] implementations need #[allow(unused_qualifications)]

[chris-morgan]

Example:

#![warn(unused_qualifications)]

use self::A::B;

#[deriving(PartialEq)]
pub enum A {
    B,
}

fn main() {
}

Output:

a.rs:7:5: 7:6 warning: unnecessary qualification
a.rs:7     B,
           ^
note: in expansion of #[deriving]
a.rs:5:1: 5:23 note: expansion site
a.rs:1:9: 1:30 note: lint level defined here
a.rs:1 #![warn(unused_qualifications)]
               ^~~~~~~~~~~~~~~~~~~~~
a.rs:7:5: 7:6 warning: unnecessary qualification
a.rs:7     B,
           ^
note: in expansion of #[deriving]
a.rs:5:1: 5:23 note: expansion site
a.rs:1:9: 1:30 note: lint level defined here
a.rs:1 #![warn(unused_qualifications)]
               ^~~~~~~~~~~~~~~~~~~~~
a.rs:7:5: 7:6 warning: unnecessary qualification
a.rs:7     B,
           ^
note: in expansion of #[deriving]
a.rs:5:1: 5:23 note: expansion site
a.rs:1:9: 1:30 note: lint level defined here
a.rs:1 #![warn(unused_qualifications)]
               ^~~~~~~~~~~~~~~~~~~~~
a.rs:7:5: 7:6 warning: unnecessary qualification
a.rs:7     B,
           ^
note: in expansion of #[deriving]
a.rs:5:1: 5:23 note: expansion site
a.rs:1:9: 1:30 note: lint level defined here
a.rs:1 #![warn(unused_qualifications)]
               ^~~~~~~~~~~~~~~~~~~~~

This is something that wasn’t an issue before, but with the scoping of enum variants can very easily become a problem now.

[retep998]

Just hit this while working on winapi. It's easy enough to just add a #[allow(unused_qualifications)] on the enum as a workaround though.