let_unit_value still has a false positive when the expression is an async function with a generic return type

[booleancoercion]

Summary

Similarly to the last comment in #8998 before it was closed, this lint is emitted in error, since the let binding is used to specify the return type in this case. Satisftying the lint by removing the let binding altogether causes a compiler error.

Lint Name

let_unit_value

Reproducer

pub async fn generic<T>() -> T {
    unimplemented!()
}

pub async fn calling_generic() {
    let () = generic().await;
}

Version

Occurs on the playground on both stable 1.67.1 and nightly 1.70.

Additional Labels

@rustbot label +l-suggestion-causes-error

[rustbot]

Error: Label l-suggestion-causes-error can only be set by Rust team members

Please file an issue on GitHub at triagebot if there's a problem with this bot, or reach out on #t-infra on Zulip.

[Jarcho]

This was fixed in #10439

[booleancoercion]

My bad, that issue was a bit hard to look up