# Error code E0077

A tuple struct's element isn't a machine type when using the `#[simd]` attribute.

Erroneous code example:

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

    fn main() {
    #[repr(simd)]
    struct Bad(String); // error!
    }

When using the `#[simd]` attribute on a tuple struct, the elements in the tuple must be machine types so SIMD operations can be applied to them.

Fixed example:

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

    fn main() {
    #[repr(simd)]
    struct Good(u32, u32, u32, u32); // ok!
    }