An async
function used recursion without boxing.
Erroneous code example:
#![allow(unused)]
fn main() {
async fn foo(n: usize) {
if n > 0 {
foo(n - 1).await;
}
}
}
ⓘ
The recursive invocation can be boxed:
#![allow(unused)]
fn main() {
async fn foo(n: usize) {
if n > 0 {
Box::pin(foo(n - 1)).await;
}
}
}
The Box<...>
ensures that the result is of known size, and the pin is
required to keep it in the same place in memory.
Alternatively, the body can be boxed:
#![allow(unused)]
fn main() {
use std::future::Future;
use std::pin::Pin;
fn foo(n: usize) -> Pin<Box<dyn Future<Output = ()>>> {
Box::pin(async move {
if n > 0 {
foo(n - 1).await;
}
})
}
}