Type inference when using the new slice syntax

[IvanUkhov]

Hello,

The following code:

#[allow(unstable)]
extern crate test;

fn foo(_: &mut[f64]) {
}

fn bar(bencher: &mut test::Bencher) {
    let mut a = vec![1.0, 2.0, 3.0];
    bencher.iter(|&mut:| foo(&mut a[])); // Works with a.as_mut_slice()
}

fn main() {
    let mut a = vec![1.0, 2.0, 3.0];
    foo(&mut a[]);
}

yields the following error:

<anon>:9:13: 9:40 error: unable to infer enough type information about `closure[<anon>:9:18: 9:39]`; type annotations required
<anon>:9     bencher.iter(|&mut:| foo(&mut a[])); // Works with a.as_mut_slice()
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error
playpen: application terminated with error code 101

However, replacing the new &mut a[] with the old a.as_mut_slice() makes it compile just fine. Presumably the type inference should work identically in the two cases.

Regards,
Ivan