Segfault with hashmap, boxes and pattern matching

[brson]

This segfaults.

extern mod std;

use std::oldmap::HashMap;

fn main() {
    let wait_map = HashMap::<int, @mut ~[int]>();
    match wait_map.find(&1) {
        Some(@ref mut waiters) => { }
        None => ()
    }
}

[catamorphism]

Reproduced. I'll take a stab at it.

[catamorphism]

Hmm, I'm not sure if this should even be legal (that is, whether it should be accepted by borrowck). And, the failure (which also happens when i change the pattern from ref mut to just ref) is a null-dereference in return_to_mut. I think I may be a bit out of my depth here.

[nikomatsakis]

I think this should be legal. Presumably we are failing to root the managed box or something like that, I'm not sure what this function return_to_mut is.

[catamorphism]

Fixed, just need to add the test case