> I can reason that the unsafe section has zero side effects outside of it There are basically a core set of invariants that `unsafe` code must hold, and you

> I can reason that the unsafe section has zero side effects outside of it There are basically a core set of invariants that `unsafe` code must hold, and you can reason about it in those terms. http://doc.rust-lang.org/nightly/nomicon/ http://doc.rust-lang.org/nightly/nomicon/ talks a lot about this.