pub unsafe fn get_eclass_for_sort_expr( arg_root: *mut PlannerInfo, arg_expr: *mut Expr, arg_nullable_relids: Relids, arg_opfamilies: *mut List, arg_opcintype: Oid, arg_collation: Oid, arg_sortref: Index, arg_rel: Relids, arg_create_it: bool) -> *mut EquivalenceClass