False type-mismatch for derive(Hash) for structs with fields called "state"

[valyagolev]

As minimal reproduction as it gets: cargo new --lib repro, then:

#[derive(Hash)]
pub enum BgGameState {
    Over, // you can comment it out as well
}

#[derive(Hash)]
pub struct BgGame {
    pub state: BgGameState, // rename it, it will go away
}

rust-analyzer version: 0.4.1521-standalone, also some earlier versions

rustc version: tried with rustc 1.69.0 (84c898d65 2023-04-16), rustc 1.71.0-nightly (521f4dae1 2023-05-19), also some earlier versions

relevant settings: It's VS Code remote on my box, via SSH, but I've been running it without issues for many months

[valyagolev]

Ohhh, I figured it out. If I rename "state", it goes away :-)

(I guess nobody ever tried to use hashing for anything with "state"... makes sense)

[HKalbasi]

Yes this happens since state is used in the macro expansion code:

impl core::hash::Hash for BgGame {
    fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
        core::mem::discriminant(self).hash(state);
        match self {
            BgGame { state: state } => {
                               // ^^^ state shadows the state
                state.hash(state);
            }
        }
    }
}

[lowr]

This should be resolved when we implement macro hygiene. Closing as a duplicate of #11681.

[flodiebold]

Maybe we could use a name that's less likely to collide until then?