Huh, finally got bitten by autoref in match - had a `match self ...` where self is by reference and the variant contains a reference, then used `ptr::hash` on the reference in the variant. The bug was that even though the ref in the variant is copy, it still got auto-ref'ed, so

`ptr::hash` gave me a hash based on the local reference to the ref, rather than the ref itself. Solution was to `match *self` instead of `self`.