Rollup merge of #104557 - eholk:dyn-star-in-traits, r=compiler-errors

Add a test case for async dyn* traits

This adds a test case that approximates async functions in dyn traits using `dyn*`. The purpose is to have an example of where we are with `dyn*` and the goal of using it for dyn traits.

Issue #102425

r? `@compiler-errors`
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Matthias Krüger 2022-11-22 00:01:08 +01:00 committed by GitHub
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// check-pass
// edition: 2021
// This test case is meant to demonstrate how close we can get to async
// functions in dyn traits with the current level of dyn* support.
#![feature(dyn_star)]
#![allow(incomplete_features)]
use std::future::Future;
trait DynAsyncCounter {
fn increment<'a>(&'a mut self) -> dyn* Future<Output = usize> + 'a;
}
struct MyCounter {
count: usize,
}
impl DynAsyncCounter for MyCounter {
fn increment<'a>(&'a mut self) -> dyn* Future<Output = usize> + 'a {
Box::pin(async {
self.count += 1;
self.count
})
}
}
async fn do_counter(counter: &mut dyn DynAsyncCounter) -> usize {
counter.increment().await
}
fn main() {
let mut counter = MyCounter { count: 0 };
let _ = do_counter(&mut counter);
}