error[E0603]: unit struct `config` is private
  --> tests/trybuild/visibility-fail.rs:15:63
   |
15 |     let srv = actix_test::start(|| App::new().service(config::config));
   |                                                               ^^^^^^ private unit struct
   |
note: the unit struct `config` is defined here
  --> tests/trybuild/visibility-fail.rs:7:5
   |
7  |     #[get("/config")]
   |     ^^^^^^^^^^^^^^^^^
   = note: this error originates in the attribute macro `get` (in Nightly builds, run with -Z macro-backtrace for more info)