warning: type `src::Zst` is more private than the item `Src::field`
  --> $DIR/should_accept_if_src_has_unreachable_field.rs:24:9
   |
LL |         pub(in super) field: Zst,
   |         ^^^^^^^^^^^^^^^^^^^^^^^^ field `Src::field` is reachable at visibility `pub(crate)`
   |
note: but type `src::Zst` is only usable at visibility `pub(self)`
  --> $DIR/should_accept_if_src_has_unreachable_field.rs:21:16
   |
LL |     #[repr(C)] pub(self) struct Zst; // <- unreachable type
   |                ^^^^^^^^^^^^^^^^^^^^
   = note: `#[warn(private_interfaces)]` on by default

warning: 1 warning emitted