I've been thinking about things like that a bit. I see a very useful and safe Rust pattern, and wonder if I can possibly implement it in C++. Mostly the answer is no, because C++ is too powerful.

I would love to proved wrong, but everything I can think of still leaves a footgun that's easy to trigger by accident, and thus negates the point of the solution.

I think the can't-reference-after-moved-from and objects-are-not-Copy-by-default are key to creating these types (at least enforced at compile time). And that would require major language changes, at least as big as the C++11 changes.