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