Sadly, bounds checking is the easy part; making sure that pointers can't become dangling is the hard one. Unfortunately, use-after-free is an extremely common security vulnerability in the wild (though it wasn't Heartbleed). We solved use-after-free in Rust, at least technically, although there were quite a few tradeoffs we had to make and the usability of the borrow checker is something we're going to need to work on post 1.0.