Error code E0778

The instruction_set attribute was malformed.

Erroneous code example:

#![feature(isa_attribute)] #[instruction_set()] // error: expected one argument pub fn something() {} fn main() {}

The parenthesized instruction_set attribute requires the parameter to be specified:

#![allow(unused)] #![feature(isa_attribute)] fn main() { #[cfg_attr(target_arch="arm", instruction_set(arm::a32))] fn something() {} }

or:

#![allow(unused)] #![feature(isa_attribute)] fn main() { #[cfg_attr(target_arch="arm", instruction_set(arm::t32))] fn something() {} }

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