[staticassertion]

????

Whatever that means lol

You mean the borrow checker? People are working on formally proving that, and have already done so for large subsets of the language.

[ColonelPhantom]

They mean that in unsafe code, you have to adhere to some rules to prevent safe code from becoming unsafe.

In other words, incorrect code in "unsafe Rust" can cause safety issues that only appear when you use it in a certain way from "safe Rust".