Bad interaction of async functions with unused_lifetimes lint

[c410-f3r]

The following shouldn't trigger the lint:

#![forbid(unused_lifetimes)]

pub async fn stuff<'a, I>(_: I) 
where
    I: Iterator<Item = &'a i32>
{
}

Also happens with &'a self or &'a mut self parameters

[tmandry]

Odd, it looks like the lint is broken for async fns. We definitely want to fix this.

If anyone wants to take this on, the place to start is check_uses_for_lifetimes_defined_by_scope and reading / logging to understand how async functions are handled differently.

[Vooblin]

Hello!
I'm new in the Rust community and I'm going to actively contribute in Rust. I would like to start with this issue.

[Vooblin]

@rustbot claim

[c410-f3r]

@Vooblin Thank you!

[tmandry]

Ping from triage. @Vooblin are you still interested in working on this?