Well, the answer to that is somewhat complicated. In Rust, a raw pointer has the same semantics of a C pointer. Could be null, could point to nowhere, the objec

Well, the answer to that is somewhat complicated. In Rust, a raw pointer has the same semantics of a C pointer. Could be null, could point to nowhere, the object pointed to could live temporarily, could live forever etc. However, there aren't any pointers which only weaken some of these conditions. The function I linked takes a possibly null raw pointer, and vouches that: 1. It points to null or something. 2. The object it points to (if it is not null) will live at least as long as the current scope. 3. The object it points to will not be mutated as long as the current scope is active. Practically speaking, as long as you don't do anything with the resulting Option<&T> other than check if it is empty, you're safe. In addition, Rust will preserve the internal pointer address, so you could bring it back to the FFI. So you could treat it consistently as such, you'll be fine. I'm not sure if the language spec guarantees that, because that's not how Rust references are designed to be used, but it won't matter in practice. For what you want, you could just create a generic structure that holds a pointer to the given type, and lets you ask if the contained pointer is null. That way you won't add any false guarantees to the pointer (e.g. immutability, lifetime, etc.).