Function layout_of_simd_ty 

fn layout_of_simd_ty<'db>(
    db: &'db dyn HirDatabase,
    id: StructId,
    repr_packed: bool,
    args: &GenericArgs<'db>,
    env: ParamEnvAndCrate<'db>,
    dl: &TargetDataLayout,
) -> Result<Arc<Layout>, LayoutError>