I wrote a small crate that does unsafe operations, please help me verify its soundness: https://github.com/lbfalvy/bound
(Also I think you'll like it, I'm solving a fairly abstract problem that's not possible in safe Rust)

It's essentially a struct that ties together a heap reference and a struct that's constructed from it. The main use case is to return lock guards derived from Arc<Mutex> but it's defined in a very abstract way intentionally because I'm using Marc from mappable-rc and async-std's RwLock and I didn't want this to depend on either crate.

It actually has no dependencies apart from STD (I think this one may be unavoidable)