`api_operation` wraps async fn body in a synchronous closure and renders `.awaiting` in it invalid

[cafce25]

The following code:

use actix_web::Responder;
#[apistos::api_operation(
    tag = "image"
)]
async fn foo() -> impl Responder {
    bar().await;
    todo!()
}
async fn bar() {}

results in:

error[E0728]: `await` is only allowed inside `async` functions and blocks
 --> src/main.rs:6:11
  |
2 | / #[apistos::api_operation(
3 | |     tag = "image"
4 | | )]
  | |__- this is not `async`
5 |   async fn foo() -> impl Responder {
6 |       bar().await;
  |             ^^^^^ only allowed inside `async` functions and blocks

when the user apparently did use an asynchronous function.

There is 2 options to resolve this:

1. Document the fact that the body of a function annotated with api_operation must be synchronous.
2. Fix the macro definition

---

Currently the macro expands to this:

fn foo() -> impl std::future::Future<
    Output = apistos::actix::ResponderWrapper<impl Responder>,
> + apistos::PathItemDefinition {
    let inner = core::future::ready(
        apistos::actix::ResponderWrapper(
            (move || {
                bar().await;
                ::core::panicking::panic("not yet implemented")
            })(),
        ),
    );
    apistos::actix::ResponseWrapper {
        inner,
        path_item: __openapi_foo,
    }
}

it could probably expand to

fn foo() -> impl std::future::Future<
    Output = apistos::actix::ResponderWrapper<impl Responder>,
> + apistos::PathItemDefinition {
    let inner = core::future::ready(
        apistos::actix::ResponderWrapper(
            async move {
                bar().await;
                ::core::panicking::panic("not yet implemented")
            }.await,
        ),
    );
    apistos::actix::ResponseWrapper {
        inner,
        path_item: __openapi_foo,
    }
}

or something similar and allow the use of .await within the body of foo.

[rlebran]

Hey, thanks for the report, I'm looking to fix the macro definition.
For your information, api_operation does support async body, there is just an issue currently with impl Responder return type.

[rlebran]

Hi, releasing apistos 0.4.0 this afternoon with a fix.
Be careful though, it comes with a MSRV bump to 1.81.0 due to a transitive dependency.