Odd error message with Iterator trait object

[jorendorff]

fn dump(iter: &Iterator<Item=i32>) {
    for s in iter {
        println!("{}", s);
    }
}

fn main() {
    let a = [1,2,3,4,5,6];
    dump(&a.iter().cloned());
}

Error output is:

<anon>:2:9: 4:10 error: the trait `core::iter::Iterator` is not implemented for the type `&core::iter::Iterator<Item=i32>` [E0277]
<anon>:2         for s in iter {
<anon>:3             println!("{}", s);
<anon>:4         }
<anon>:2:9: 4:10 help: see the detailed explanation for E0277
<anon>:2:9: 4:10 note: `&core::iter::Iterator<Item=i32>` is not an iterator; maybe try calling `.iter()` or a similar method
<anon>:2:9: 4:10 note: required by `core::iter::IntoIterator::into_iter`
error: aborting due to previous error

Adding mut to the trait object type on line 1, and the corresponding borrow on line 9, fixes it. My question is, can the error message be improved?

[Mark-Simulacrum]

Closing in favor of #32627.

[jorendorff]

@Mark-Simulacrum This is #32627. Which issue did you mean to link to? :)

[Mark-Simulacrum]

Ah.. #37914. GH should really warn you about this...