Practically everything will be marked by it. Using `Vec`? Marked. Reading file? Marked. Printing something to stdout? Marked. The idea behind Rust's unsafe is

Practically everything will be marked by it. Using `Vec`? Marked. Reading file? Marked. Printing something to stdout? Marked. The idea behind Rust's unsafe is to cover unsafe bits in safe API which (assuming correctness of the unsafe code) can not be misused to cause memory issues in safe Rust.