#### Note: this error code is no longer emitted by the compiler This is because it was too specific to the `inline` attribute. Similar diagnostics occur for other attributes too. The example here will now emit `E0539` Erroneous code example: ```compile_fail,E0539 #[inline(unknown)] // error: invalid argument pub fn something() {} fn main() {} ``` The `inline` attribute only supports two arguments: * always * never All other arguments given to the `inline` attribute will return this error. Example: ``` #[inline(never)] // ok! pub fn something() {} fn main() {} ``` For more information see the [`inline` Attribute][inline-attribute] section of the Reference. [inline-attribute]: https://doc.rust-lang.org/reference/attributes/codegen.html#the-inline-attribute