[dbaupp]

An `unsafe` block only enables extra features, it doesn't change existing behaviour of safe Rust. Specifically, it allows calling `unsafe` functions (FFI and pure Rust `unsafe` ones), dereferencing raw pointers and some minor other stuff (e.g., inline assembly, some manipulations of packed structs). The borrow checker still works on references, the trait system still enforces Send/Sync for concurrency, and the type system still requires things to have matching types.

It's definitely true that having a one dimensional `unsafe` might seem unnecessarily powerful in some cases (e.g. an particular unsafe block might just need to do some pointer offsetting and dereferencing, but no FFI), but it isn't a "you're on your own" hammer.