{"ast_node_type":"other","tokens":[{"end":66,"kind":"keyword","start":0,"text":"assert_eq!(unique_ptr.layout().fields.count(),"}]}
                assert_eq!(unique_ptr.layout().fields.count(), 2);
                // (which means another 2 fields, the second of which is a `PhantomData`)
                let [nonnull_ptr, phantom] =