Error code E0075

A #[simd] attribute was applied to an empty or multi-field struct.

Erroneous code examples:

#![allow(unused)] #![feature(repr_simd)] fn main() { #[repr(simd)] struct Bad; // error! }
#![allow(unused)] #![feature(repr_simd)] fn main() { #[repr(simd)] struct Bad([u32; 1], [u32; 1]); // error! }

The #[simd] attribute can only be applied to a single-field struct, because the one field must be the array of values in the vector.

Fixed example:

#![allow(unused)] #![feature(repr_simd)] fn main() { #[repr(simd)] struct Good([u32; 2]); // ok! }