I&#x27;m a Rust fan, but I&#x27;ll still be excited if Swift manages to add some sort of borrow checker to the language in a future revision (C++, D, and Nim have all also at least alluded towards such a direction, but only C++ has made any progress so far). From what I&#x27;ve seen though, I&#x27;m still not sure that Chris Lattner has given serious thought to such an addition. I&#x27;m waiting for a concrete proposal before getting my hopes up, because Rust had to make put significant effort into tailoring the base language to borrow checking and implementing such an analysis after the fact runs the risk of serious divergence (or worse, breakage) in the ecosystem.<p>(There&#x27;s also the fact that, as of the hypothetical Swift 4k, none of the library ecosystem will be leveraging the borrow checker and so Rust will still have a substantial head start for people who want thoroughly static ownership.)<p>Other than that I&#x27;m a bit dismayed that Swift just punts concurrency to GCD, given how many other new languages make concurrency such a major focus (especially Rust).