`--world-safe`, `-ws` A command flag that displays packages that can be safely removed from the world file. In other words, packages that are an installed dependency of another package and are present in the world file. Won't be picked up by `emerge -c` upon removal from the world file. This is useful to catch certain unintentional slip-ups and manage the world file appropiately. I would be willing to make a merge request but I have zero experience or knowledge with the Portage API.