I was reading a topic on main forum, when I realised that neither Drain types in std nor drain functions that return them are marked as #[must_use]. This makes following code compile without warnings: fn main() { let mut s = "hi there".to_owned(); s.drain(2..6); println!("{s}"); } I'm quite surprised by this. It is of course perfectly fine to drop Drain type. Unless it is forgotten there is no memory leak, so the only consequence of dropping it is that drained items are dropped as ...
