Looking at the presentation it looks like you can borrow a non-const reference (in rust parlance) several times, so there&#x27;s no concurrency guarantee.<p>You would have to break compatibility with too much existing code to get the same level of strictness as Rust, so that&#x27;s reasonable, but yeah, it&#x27;s hard to imagine that C++ will be as safe as Rust. I&#x27;m glad these features are being pushed through though.