Now bitflags merely derives PartialOrd with the mechanism built into rustc, which compares the values numerically. But a flags type is also a Boolean lattice, so it has another natural partial order: x ≤ y iff y.contains(x). As i can't disable deriving PartialOrd i can't use if the other semantics if wanted.

Either option would be fine:
• Let user disable deriving PartialOrd (and ergo Ord)
• Let user choose the semantics of PartialOrd per type