[Mateon1]

The `single_ref` field is a fixed-size array in both of the objects referenced in this line, so this line can't panic, and no bounds checks are involved (since the compiler sees the index < length at compile time and doesn't even need to emit one -- although I think it still does, and it's LLVM that gets rid of it actually)

Causing memory leaks is possible in safe Rust even without any arcane invocations, you can construct a cycle of Rc<T> counted objects. There's even a perfectly safe Box::leak in the standard library that gives you a &'static reference to any object by leaking it. Preventing leaks is outside of the scope of Rust's safety system.