Understanding Rust Error E0779: Unknown Argument in instruction_set Attribute

Introduction to Error E0779

Rust Error E0779 occurs when an unknown or invalid argument is provided to the instruction_set attribute. This error is meant to catch cases where the specified instruction set for a function is not recognized by the Rust compiler.

Official Documentation Example


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

Currently, the instruction_set attribute supports only two arguments in Rust: 1. arm::a32 2. arm::t32

Working Example


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

Common Causes for Error E0779

Some typical scenarios that can trigger Rust Error E0779 include: 1. Misspelling a supported instruction set argument. 2. Specifying an unsupported instruction set argument. 3. Using the wrong attribute syntax.

How to Fix Error E0779

To resolve Rust Error E0779, you can take the following steps: 1. Ensure you're using a supported instruction set argument. 2. Verify that the argument has been spelled correctly. 3. Correct the attribute syntax if necessary.


By understanding the underlying cause of Rust Error E0779 and ensuring correct use of the instruction_set attribute and its supported arguments, you can ensure that your functions will be compiled using the intended instruction set. This will help improve code performance and maintainability.