Error code E0779

An unknown argument was given to the instruction_set attribute.

Erroneous code example:

#![feature(isa_attribute)]

#[instruction_set(intel::x64)] // error: invalid argument
pub fn something() {}
fn main() {}

The instruction_set attribute only supports two arguments currently:

• arm::a32
• arm::t32

All other arguments given to the instruction_set attribute will return this error. Example:

#![feature(isa_attribute)]

#[cfg_attr(target_arch="arm", instruction_set(arm::a32))] // ok!
pub fn something() {}
fn main() {}

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