I have a C library that accepts data as C void * (sometimes with a size), and I'd like to expose an interface that exposes a generic type-checked interface. I thought that I could write a trait for types that can be transformed to a C void * and back, such as &'static T and Box<T>, but also usize and Rc<T>. My first question is whether there is a crate that already provide something similar (I didn't find one).
Then, if there's no crate that I can use, I'd also like some feedback on my current design for this. I'm thinking about using two traits for thin and fat pointers respectively (as the library sometimes accepts a size along the void pointer). Each trait would have methods to convert to and from void *, and a method to obtain a reference to the value from a void *. There likely would be a blanket impl of the fat pointer trait for types implementing the thin pointer one. I'm also wondering about using a third super trait to convert to a void * and size, instead of duplicating these functions in the two other traits, or having to manually implement both traits for thin pointers.
