They can't now. They could up to and almost including 1.0. At that point the consensus was that memory leaks were unsafe and so unsafe code could rely on them not happening. That code was not incorrect! It just had assumptions that were false. One solution was to make those assumptions true by outlawing memory leaks. The original memory leak hack to trigger memory corruption was fairly fiendish in combination with scoped threads (IIRC).
>There are plenty of undesirable behaviors that fall outside of this definition of unsafety. Memory leaks are simply one example.
That is my whole point. It is a useless definition cherry-picked by Rust because it is what Rust, in theory, prevents. It does not precede Rust. Rust precedes it.
>It is the same yardstick used by other memory-safe languages- for instance, despite your claims to the contrary, garbage collectors do not and cannot guarantee a total lack of garbage. They have a lot of slack to let the garbage build up and then collect it all at once, or in some situations never collect it at all.
If it will eventually be collected then it isn't a memory leak.
Most actual safe languages don't let you write integer overflow.