> Isn't it the case that once you use unsafe even a single time, you lose all of Rust's nice guarantees? No, not even close. You only lose Rust's safety guaran

> Isn't it the case that once you use unsafe even a single time, you lose all of Rust's nice guarantees? No, not even close. You only lose Rust's safety guarantees when your unsafe code causes Undefined Behavior. Unsafe code that can be made to cause UB from Safe Rust is typically called unsound, and unsafe code that cannot be made to cause UB from Safe Rust is called sound. As long as your unsafe code is sound, then it does not break any of Rust's guarantees. For example, unsafe code can still use slices or references provided by Safe Rust, because those are always guaranteed to be valid, even in an unsafe block. However, if from inside that unsafe block you then go on to manufacture an invalid slice or reference using unsafe functions, that is UB and you lose Rust's safety guarantees because of the UB.