The first function is wrong because it leaves the compiler the discretion to do something dangerous. But isn't that the same problem as the second function? The

The first function is wrong because it leaves the compiler the discretion to do something dangerous. But isn't that the same problem as the second function? The compiler has much more discretion in the first case, all the way to nasal demons and flying monkeys, but that's little consolation when the discretion it does have in the second case is to do exactly the thing that makes the function insecure. "Whatever it decides to do is ok," but some of the things it can decide to do will leak your password hashes. Throw in Spectre and it's a huge mess, because it's not just the password hashing function leaking the password hashes, it's anything with an exploitable bounds check that can reach the memory where they're stored.