With mere “guidelines”, there is no practical, unambiguous way to establish without a shadow of doubt that a function implemented using unsafe Rust upholds the

With mere “guidelines”, there is no practical, unambiguous way to establish without a shadow of doubt that a function implemented using unsafe Rust upholds the safety guarantees of safe Rust. So I want a proper formal semantics, maybe not for all of Rust, but at least for a fragment interesting enough to express lifetime and mutability concerns. In particular, I want a formal account of interior mutability.