error[E0603]: unit struct `not_public` is private
  --> tests/compile_fail/not_public.rs:14:13
   |
14 |     hidden::not_public(1);
   |             ^^^^^^^^^^ private unit struct
   |
note: the unit struct `not_public` is defined here
  --> tests/compile_fail/not_public.rs:6:5
   |
6  |     fn_overloads! {
   |     ^^^^^^^^^^^^^
   = note: this error originates in the macro `fn_overloads` (in Nightly builds, run with -Z macro-backtrace for more info)