[ordu]

> Rust requires a lot of runtime checks, but that's the price one has to pay for memory safety.

It requires a lot of runtime checks on the boundary between rust and C/C++ code. You cannot trust C/C++ code, so you are forced to check everything. C-function returns a enum value? Check that this value is in the enum, before converting it to the rust enum. Check that there are no situations like

    enum MyEnum {
        val1, val2=5
    };
    enum MyEnum foo() {
        return 42;
    }

But after you've done all that checks you need to check almost nothing, because if you have a enum value in Rust, you know for sure that it is a valid value. And compiler knows that the value is valid and optimizes accordingly. If you have an &str, you know that it is a valid utf8, you need not to check it on each access, it have been checked already. You got a valid pointer from C? Wrap it into NonNull, so neither you, nor compiler would need to check validity of a pointer once more.

It is unclear thing, who needs more checks -- safe code or unsafe code. I'm gravitating to a belief that unsafe code needs much more runtime checks.