Internal compiler error while fighting with traits

[nefigah]

rustc 1.0.0-nightly (3ef8ff1 2015-02-12 00:38:24 +0000)
binary: rustc
commit-hash: 3ef8ff1
commit-date: 2015-02-12 00:38:24 +0000
host: x86_64-apple-darwin
release: 1.0.0-nightly

src/util.rs:44:25: 44:30 error: mismatched types:
 expected `&_`,
    found `Self`
(expected &-ptr,
    found Self) [E0308]
src/util.rs:44         let indexer = &(*self as &Index<usize, Output = <Self as Index<usize>>::Output>);
                                       ^~~~~
src/util.rs:44:25: 44:30 error: internal compiler error: expected appropriate reference type
src/util.rs:44         let indexer = &(*self as &Index<usize, Output = <Self as Index<usize>>::Output>);
                                       ^~~~~
note: the compiler unexpectedly panicked. this is a bug.

Having a hell of a time getting some code to typecheck, and apparently broke the compiler with one attempt. Here's the code:

pub trait Array2D: Index<usize> {
    fn rows(&self) -> usize;
    fn columns(&self) -> usize;
    fn get<'a>(&'a self, y: usize, x: usize) -> Option<&'a <Self as Index<usize>>::Output> {
        if y >= self.rows() || x >= self.columns() {
            return None;
        }
        let i = y * self.columns() + x;
        let indexer = &(*self as &Index<usize, Output = <Self as Index<usize>>::Output>);
        Some(indexer.index(&i))
    }
}

[tamird]

@nefigah this example is incomplete. Can you add the definition of Index?

[nefigah]

@tamird I'm afraid I don't understand. The bound on my trait is just referring to std::ops::Index – (which was recently changed to take the argument of index() by value, instead of by reference like at the time I reported this issue and previously)

[tamird]

@nefigah ah, thanks.

Triage: no longer ICEs.

use std::ops::Index;

pub trait Array2D: Index<usize> {
    fn rows(&self) -> usize;
    fn columns(&self) -> usize;
    fn get<'a>(&'a self, y: usize, x: usize) -> Option<&'a <Self as Index<usize>>::Output> {
        if y >= self.rows() || x >= self.columns() {
            return None;
        }
        let i = y * self.columns() + x;
        let indexer = &(*self as &Index<usize, Output = <Self as Index<usize>>::Output>);
        Some(indexer.index(i))
    }
}

fn main() {
    // Add code here
}

$ rustc main.rs
main.rs:11:25: 11:88 error: non-scalar cast: `Self` as `&core::ops::Index<usize, Output=<Self as core::ops::Index<usize>>::Output>`
main.rs:11         let indexer = &(*self as &Index<usize, Output = <Self as Index<usize>>::Output>);
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error