Actix and Inventory crate

Question

I'm trying to make it possible to register an actix route automatically. To do so I found the crate Inventory which seems to answer my need.
I have the following code:

#[get("/hello2/{name}")]
async fn greet2(req: HttpRequest) -> String {
    let name = req.match_info().get("name").unwrap_or("World");
    let a = format!("Hello2 {}!", &name);
    a
}

pub struct TestStruct {
    test: fn(HttpRequest) -> dyn Future<Output = String>
}

inventory::collect!(TestStruct);

inventory::submit! {
    let mut a = TestStruct {
        test: <greet2 as HttpServiceFactory>::register
    };
    a.test.push(greet2::register::greet2);
    a
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    HttpServer::new(move || {
        let mut app = App::new();
        for route in inventory::iter::<AutomaticHttpService> {
            app = app.service(route);
        }
        app
    })
        .bind(("127.0.0.1", 8080))?
        .workers(2)
        .run()
        .await
}

My code does not compile as I cannot access the requested function pointer and I cannot use the HttpServiceFactory trait as it is not declared in the same file. I also tried to use the std::any::Any type and then cast to HttpServiceFactory (maybe using unsafe) but without success because its size was not known at compile time. Would you have any clues to unblock my situation?