Fuzzing can help with that. But it’s not only applicable to Rust.
For Actix web he was using “unsafe” to increase performance. That doesn’t mean the code written was unsafe… The Rust community was turning to a cult on this topic when perfectly experienced C++ can write code would need the unsafe in Rust when they perfectly know the code isn’t. It’s good for the community to push people to avoid to use unsafe but not to that extend of drama and bullying…