Move out of reference in move closures

[arora-aman]

struct S {
    x: String,
    y: String
}

fn x(s: &mut S) {
    let mut c = move || {
        s.x.truncate(0);
    };
    c();
}


fn main() {
    let mut s = S { x: "".into(), y: "".into() };
    x(&mut s);
}

Without the feature gate s which is a &mut S is moved. However with the feature gate *s.x is moved which is a String which behind a &mut S and can't be moved out.

[nikomatsakis]

notes: https://hackmd.io/CdxyYchnRfyIxZHeykyvoA

[arora-aman]

Update from 2229 sync meeting:

• We drop any Derefs in case of move closures.

[arora-aman]

https://hackmd.io/PzxYMPY4RF-B9iH9uj9GTA

[arora-aman]

First part implemented here: rust-lang/rust#80092