An invalid number of generic parameters was passed to an intrinsic function. Erroneous code example: ```compile_fail,E0094 #![feature(intrinsics, rustc_attrs)] #![allow(internal_features)] extern "rust-intrinsic" { #[rustc_safe_intrinsic] fn size_of() -> usize; // error: intrinsic has wrong number // of type parameters } ``` Please check that you provided the right number of type parameters and verify with the function declaration in the Rust source code. Example: ``` #![feature(intrinsics, rustc_attrs)] #![allow(internal_features)] extern "rust-intrinsic" { #[rustc_safe_intrinsic] fn size_of() -> usize; // ok! } ```