Pre-Pre-RFC: adding a must_use_async attribute

language design
1

When recently working in an async code base I have spent a total of a few hours debugging issues that were simply "oops I didn't await that"

#[must_use_async]
async fn foo() {}

async fn main() {
    foo()
}

would cause an error/warning, something like using an async fn without calling .await has no effect.

2

Would you mind providing a better example? Yours (if “fixed” by adding a semicolon) gives a warning.

warning: unused implementer of `std::future::Future` that must be used

Including the note

note: futures do nothing unless you `.await` or poll them`
3

Oh no this is embarrassing I was working in a project with #[allow(unused)] nooooo.

Thanks for taking the time to respond I thought it was super odd that the compiler wasnt saying anything sorry.

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4

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