Ebuilds must not try to manipulate variables like DIROPTIONS or INSOPTIONS directly. They should use the diropts or insopts functions instead. PMS does not list *OPTIONS in the list of defined variables (i.e. those that are exported to the ebuild environment); the Devmanual does not mention these variables at all. Policy references: Devmanual: Install Functions Reference https://devmanual.gentoo.org/function-reference/install-functions/index.html PMS: Section 11.1 Defined Variables https://projects.gentoo.org/pms/6/pms.html#x1-118002
Looks like all uses are gone now.
