how do I use wrap in route macro? How instantiate struct for wrap?

[anatawa12]

My code cannot be compiled with E0423. How do I use wrap in route macro?

pub struct GithubTokenValidator {
}

impl Default for GithubTokenValidator {
    fn default() -> Self {
        Self::new()
    }
}

impl<S, B> Transform<S> for GithubTokenValidator ... { ... };

//#[post("/event_handler", wrap="GithubTokenValidator {}")] // says `error: unexpected token`
#[post("/event_handler", wrap="GithubTokenValidator")]
async fn event_handler(ctx: web::Data<AppContext>, body: Bytes, req: HttpRequest) -> Result<impl Responder, Error> {
    Ok("")
}

error[E0423]: expected value, found struct `GithubTokenValidator`
  --> src/main.rs:30:31
   |
30 |   #[post("/event_handler", wrap="GithubTokenValidator")]
   |                                 ^^^^^^^^^^^^^^^^^^^^^^ help: use struct literal syntax instead: `GithubTokenValidator {}`
   | 
  ::: src/middle_ware.rs:18:1
   |
18 | / pub struct GithubTokenValidator {
19 | | }
   | |_- `GithubTokenValidator` defined here

[anatawa12]

[Self-solving]

I found we can use expressions like GithubTokenValidator::new(). However, we can't use expressions GithubTokenValidator {}