fn insert(&mut self, span: Span, hir_id: HirId, node: Node<'hir>) {
debug_assert_eq!(self.owner, hir_id.owner);
debug_assert_ne!(hir_id.local_id.as_u32(), 0);
+ debug_assert_ne!(hir_id.local_id, self.parent_node);
// Make sure that the DepNode of some node coincides with the HirId
// owner of that node.