I assume your commentary is that this is bad, but I'd like to know why. I see this criticism thrown at lots of libraries.
All safe code in rust is built on unsafe code. The standard library is full of unsafe code. The purpose of `unsafe` is to encourage that dangerous things are safely wrapped. In business logic I'd question using unsafe code directly, but in a performance critical low level memory management library that's exactly where I'd expect to see it.
> The standard library is full of unsafe code.
Yes, and this means that for me to trust that the code is memory safe I need to trust the people who develop the standard library (or validate the unsafe usage myself). Rust has a good track record and a very good review process to ensure correctness of their "unsafe" block.
This library however? Do they know how to write "unsafe" blocks? I don't know! Maybe? If there were zero uses of "unsafe" in this library I would be able to adopt it without worrying about memory safety at all. In addition, I'm not that good at knowing whether an "unsafe" block is safe myself. It's not like I can review this cases myself and be confident.
(Memory safety is of course not everything, but bugs related to memory safety are much more annoying than other types of bugs.)
I gave no commentary. I don't even know what to say about that disclaimer. But I am not a Rust fan and I think "safety" should be achieved through making good programming easy.