The problem here is that we don't want a mutex. Once you have it the performance cost would apply in runtime. In fact, to write this code in rust you would need

The problem here is that we don't want a mutex. Once you have it the performance cost would apply in runtime. In fact, to write this code in rust you would need to write unsafe code to get around the problem where Rust forces you to write correct but inefficient code. This code is intentionally not thread-safe. This isn't so much a bug but an interesting thought experiment.