Qualified associated type in generic parameter needs a space separating the <<

[japaric]

STR

#![feature(associated_types)]

trait Trait {
    type Type;

    // OK
    fn method() -> <Self as Trait>::Type;
    // Can't parse
    fn method() -> Box<<Self as Trait>::Type>;
}

fn main() {}

Output

ai.rs:9:23: 9:25 error: expected `;` or `{`, found `<<`
ai.rs:9     fn method() -> Box<<Self as Trait>::Type>;

Version

rustc 0.12.0-pre (9508faa22 2014-09-17 23:45:36 +0000)

cc @pcwalton

[huonw]

I guess this works if you put a space in between the two <s?

[japaric]

You're right @huonw! I didn't see anything like that in the tests (maybe I missed it), so I didn't think it would work.

Closing

[huonw]

This still seems like a grammar annoyance.