I'm not saying a theoretical language couldn't be made that allows this, but in Rust it would be breaking backwards compatibility.

For example [T]::sort (obviously) needs to be able to move the elements in the passed array, but there is no Move bound on T or something similar.

> It basically does if you use pin.

And we have Pin today, but I assumed the OP meant 'self-referential struct' as in, without using Pin.