Let Option derive #[must_use]

[dhardy]

Let Option and Box derive #[must_use] from their generic parameter T.

Rendered

[burdges]

Is there some reason #[must_use] should not be a marker trait?

[Lokathor]

I would say that actually must_use is more a property of a particular function, not really of types, and sticking it on types is a shorthanded way to put it on a lot of functions "for free" cognitively. I'd say it's best if we, as an ecosystem, stick to having must_use on functions/methods rather than types.