mozilla/rust — pull request #7765 by blake2-ppc (2013-07-13 02:32:48+00:00)
Title: cmp: Use default methods in trait Ord, only require Ord::le

Rust will allow to supply default methods for all four methods, but we
don't have any nice error reporting for the case where at least one
method must be implemented, but it's arbitrary which.

So in this case, we require `le`, but allow implementing the others if needed.