[0815test]

Cell<T> (1) is not safe to reference across threads, and (2) can only mutate via the equivalent of a memcpy. It can be useful in many ways, but there is a real sense in which &T and &mut T (which would probably be called &uniq T, if Rust devs cared about theoretical cleanness over reusing short keywords!) are truly fundamental.

[Rusky]

Point 2 is only a limitation of the current standard library, not of the language-level model. It has even been relaxed recently, so you can go from a &Cell<[T]> to a &[Cell<T>]: https://github.com/rust-lang/rust/pull/61620

The same could be done for struct fields if the type system knew about it, and the whole thing could just use normal syntax.

Sharing between threads still needs &T or &mut T (or an owned value), but that's not usually involved in the painful cases.