That is literally what I mentioned as a possible reason ("except possibly ..."), but what I overlooked was that you could take a mutable reference to the &[T] inside a Option<&[T]>, then store a valid &[T] into it - if NULL is allowed, you effectively mutated the discriminant of a enum when you have active references to its fields, violating some aspect of type/memory safety, even I'm not sure which.
> C generally chooses NULL, Rust happens to choose a different value.
It's not about what pointer value the langauge chooses when it's asked to create a zero-length slice, it's about whether the language accepts a NULL pointer in a zero-length slice it finds lying around somewhere.
Thanks.
> having Option<&[T]> be the same size as &[T]
That is literally what I mentioned as a possible reason ("except possibly ..."), but what I overlooked was that you could take a mutable reference to the &[T] inside a Option<&[T]>, then store a valid &[T] into it - if NULL is allowed, you effectively mutated the discriminant of a enum when you have active references to its fields, violating some aspect of type/memory safety, even I'm not sure which.
> C generally chooses NULL, Rust happens to choose a different value.
It's not about what pointer value the langauge chooses when it's asked to create a zero-length slice, it's about whether the language accepts a NULL pointer in a zero-length slice it finds lying around somewhere.