Understanding and Fixing Rust Error E0094

Introduction to Rust Error E0094

Rust Error E0094 occurs when an invalid number of generic parameters are passed to an intrinsic function. In this article, we'll go over the error, provide examples of erroneous code, and guide you on how to fix it.

Erroneous Code Example

Below is an example of code that triggers Rust Error E0094 due to an incorrect number of type parameters:

#![allow(unused)]
#![feature(intrinsics)]

fn main() {
extern "rust-intrinsic" {
    #[rustc_safe_intrinsic]
    fn size_of<T, U>() -> usize; // error: intrinsic has wrong number
                                 //        of type parameters
}
}

How to Fix Rust Error E0094

To fix Rust Error E0094, you need to ensure that you provide the correct number of type parameters to the intrinsic function. Verify the function declaration in the Rust source code to determine the appropriate number of type parameters.

Corrected Code Example

Here's the corrected code example with the proper number of type parameters for the size_of intrinsic function:

#![allow(unused)]
#![feature(intrinsics)]

fn main() {
extern "rust-intrinsic" {
    #[rustc_safe_intrinsic]
    fn size_of<T>() -> usize; // ok!
}
}

Conclusion