{"ast_node_type":"other","tokens":[{"end":83,"kind":"keyword","start":0,"text":"ty::FnPtr(..)"}]}
                ty::FnPtr(..) => Some("function pointers must be non-null".into()),
                ty::Adt(..) if ty.is_box() => Some("`Box` must be non-null".into()),
                ty::Never => Some("the `!` type has no valid value".into()),