Error code E0534

The inline attribute was malformed.

Erroneous code example:

#[inline()] // error: expected one argument pub fn something() {} fn main() {}

The parenthesized inline attribute requires the parameter to be specified:

#![allow(unused)] fn main() { #[inline(always)] fn something() {} }

or:

#![allow(unused)] fn main() { #[inline(never)] fn something() {} }

Alternatively, a paren-less version of the attribute may be used to hint the compiler about inlining opportunity:

#![allow(unused)] fn main() { #[inline] fn something() {} }

For more information see the inline attribute section of the Reference.