use auxiliary_macro::hidden_repr_cfg_not_any; use pin_project::pin_project; // `#[hidden_repr_cfg_not_any(packed)]` generates `#[cfg_attr(not(any()), repr(packed))]`. #[pin_project] #[hidden_repr_cfg_not_any(packed)] //~ ERROR may not be used on #[repr(packed)] types struct S { #[pin] f: u32, } fn main() {}