There's not a module-level Safe/Trustworthy/Unsafe division, but as steveklabnik1 says, any potentially-dangerous code has to be placed into an `unsafe` block.
One can also forbid the use of any `unsafe` blocks for a crate/module (with the #[forbid(unsafe_code)] attribute), but this is slightly different to the {-# LANGUAGE Safe #-} pragma in that it does consider imports at all. However, since "unsafety" is modeled in the language in Rust, and is granular, people are encouraged to have every module be "Trustworthy" (in Safe Haskell terms): if an individual function could cause undefined behaviour if misused, it should be marked "unsafe", and a "Safe" module (i.e. one using the forbid above) won't be able to use it.
Re:The Value of Undefined Behavior
by steveklabnik on Sunday July 22, 2018 @04:09AM
(#17585787)
Rust requires you to to explicitly mark individual blocks of code as unsafe, and you can only do unsafe operations inside of them.
I have no idea whether any equivalent exists for Rust.