[jojomodding]

The explanation of `Unique` is a bit botched. `Unique` was originally intended to convey uniqueness in the sense of `noalias`, so that more compiler optimizations are possible similar to what happens around mutable references. This is what the article seems to suggest is going on .

But this is wrong, it is no longer the case that `Unique` implies any extra optimizations, since it was since recognized that having these optimizations on a low-level unsafe building block is actually undesirable. Further, the `as_ref` functions mentioned in the article are not used by `Vec`'s internals. They are anyways only marked unsafe because they create references, not because of anything special with `Unique`.

Nowadays, all that `Unique` does is interact with `dropck` in a quirky way, the "exception to the exception." It is quite complicated and I always have to read up on it. It is explained in the Rustonomocon, in the "Click here to see why" section of this chapter: https://doc.rust-lang.org/nomicon/phantom-data.html#an-excep...

[marekzan]

Hey, author here :).

Thank you for your critique and you are right, I struggled with this chapter a lot.

I will read the link to get a better understanding of this type and update the section.

If I may ask, do you have more sources where I can read up on the history and current uses of unique besides the rustonomicon?

Thank you again for your engagement! It is very helpful to get these insights from people with more knowledge.