Can define and use async fn without feature gate on nightly

[Nemo157]

#![feature(futures_api)]

pub struct Foo;

impl Foo {
    pub async fn foo(&mut self) {
    }
}

fn main() {
    let mut bar = Foo;
    bar.foo();
}

(playground) runs without error, for some reason the async_await feature gate is not required.

(cc @nikomatsakis @cramertj)

[pnkfelix]

@Nemo157 Just to be clear: Is there a way to access async fn with no feature gate at all? The provided example is at least opting into #![feature(futures_api)].

If one must use some feature gate to use async fn, then I'd be tempted to prioritize this as P-medium, not P-high.

[pnkfelix]

(leaving nominated and unprioritized for now, at least until above question is resolved.)

[pnkfelix]

triage: Based on @eddyb's statement that our plan is to stabilize futures "soon", I'll assign this P-high priority for now. Leaving nominated due to the question I posted above.

[Nemo157]

@pnkfelix not that I could find, but futures_api is currently in FCP for stabilization.

[varkor]

Stabilisation issue: #59725