4 ms·

That function was using an unsafe block to disable the bounds check. This kind of bug would likely be impossible in "safe" rust (that didn't use unsafe).

• ajross 3y ago
  The linked glibc code was likewise being fancy trying to use a stack buffer to avoid a heap allocation. Idiomatic C would have worked just fine too. The point is that Rust is also (though not as severely) subject to developers playing tricks and hurting themselves.
• uecker 3y ago
  In reality people use unsafe to optimize and then introduce bugs. You could also use a safe abstractions to avoid bounds violations in C.
  • zamalek 3y ago
    That isn't the use-case for unsafe. If you see a codebase doing this then you should stop paying attention to or using that codebase. Unsafe is for creating things that are beyond the understanding of the borrow checker. For example, using unsafe is mandatory for creating a mutex because the safety rules are upheld by the data structure itself. Unsafe is not "C mode" as most would assume - it is more unsafe than C because if you don't uphold the memory model things will break. Rust's strict aliasing and mutability rules provide ample opportunity for compiler optimizations and zero cost abstractions. Turning to unsafe is generally a sign of incompetence/arrogance.