Understanding Rust Error E0703: Invalid ABI Usage

Introduction to Rust Error E0703

Rust Error E0703 occurs when an invalid Application Binary Interface (ABI) is used in the code. An ABI specifies how functions should be called, data structures represented, and many other low-level details required when different languages and systems interact. In Rust, only a few predefined ABI strings can be used, and using an invalid ABI causes this error.

Example of Erroneous Code

extern "invalid" fn foo() {} // error!
fn main() {}

In the code example above, the ABI string "invalid" is not a predefined one for Rust. As a result, the error E0703 is triggered.

Resolving Rust Error E0703

To resolve Rust Error E0703, you need to replace the invalid ABI with a valid predefined ABI string. The predefined ABIs in Rust include 'Rust', 'C', and 'system'. Use one of these ABIs to correct the error.

Example of Corrected Code

extern "Rust" fn foo() {} // ok!
fn main() {}

In the corrected code example, the invalid ABI has been replaced with the 'Rust' ABI, resolving the error.

Other Predefined ABIs in Rust

Here are some other predefined ABIs in Rust that you might use: - 'C': Specifies that the function follows the C calling convention. - 'system': Specifies that the function follows the platform's system calling convention. It's usually the same as the 'C' calling convention. By using one of the predefined ABIs available in Rust, you can avoid Rust Error E0703.