Finding types of expressions yields "unknown" for generic types

[sdroege]

fn main() {
    let a = Some(3);
    let _b = a.and_then(|a1| a.map(|a2| a1 + a2));
    let c = std::sync::Mutex::new(2);
    let d = c.lock().unwrap();
    assert_eq!(*d, 2);
}

All variables are detected as "unknown" type here. This also has the side-effect that no autocomplete suggestions are provided (for example when typing a.and_ it gave nothing, or c.loc etc.).

Even when doing let c: std::sync::Mutex<i32> = ... the type of c is unknown (or the equivalent for a with Option<i32>.

[lnicola]

Hmm..

[bjorn3]

Is the rust-src rustup component installed?

$ rustup component list | grep rust-src
rust-src (installed)

[sdroege]

Indeed, that was it. I'm sure I installed it before but apparently not (or not in this machine?). Sorry for the noise!

[matklad]

Yet another thing which we can show in status... cc #4074