8. Freedom from safety: unsafe mode

Programs written in Rust benefit from a high level of security, guaranteed by strong constraints verified at compile-time. But for certain applications, such as close interaction with hardware or code generation, these constraints are too strong. Rust provides a way of avoiding them for certain delicate parts of a program, while retaining them for the rest of the program: unsafe mode.

An unsafe program section is indicated by the keyword unsafe followed by the block containing the unsafe code, which can perform five unsafe actions:

• dereference a raw pointer; a raw pointer can escape possession and borrowing rules, as well as the automatic memory release system;

• calling an unsafe function or method ;

• access a modifiable static variable ;

...