Error code E0551

Note: this error code is no longer emitted by the compiler

An invalid meta-item was used inside an attribute.

Erroneous code example:

#![allow(unused)] fn main() { #[deprecated(note)] // error! fn i_am_deprecated() {} }

Meta items are the key-value pairs inside of an attribute. To fix this issue, you need to give a value to the note key. Example:

#![allow(unused)] fn main() { #[deprecated(note = "because")] // ok! fn i_am_deprecated() {} }