Almost exactly one month ago I have a junior developer share the same shared_ptr across threads, where some threads could be writing to it by calling reset(). T

Almost exactly one month ago I have a junior developer share the same shared_ptr across threads, where some threads could be writing to it by calling reset(). They forget that accessing the shared_ptr itself needs to be protected. Rust prevents this problem completely though. You are either going to deal with Arc<Mutex<T>> or Mutex<Arc<T>>, depending on the situation (in this case the latter), and forgetting the Mutex will simply cause compilation failure.