All types in a tuple struct aren't the same when using the #[simd] attribute.

Erroneous code example:

#![feature(repr_simd)]

#[repr(simd)]
struct Bad(u16, u32, u32); // error!

When using the #[simd] attribute to automatically use SIMD operations in tuple struct, the types in the struct must all be of the same type, or the compiler will trigger this error.

Fixed example:

#![feature(repr_simd)]

#[repr(simd)]
struct Good(u32, u32, u32); // ok!