//@ edition: 2021 trait MyTrait { async fn foo_recursive(&self, n: usize) -> i32; } impl MyTrait for i32 { async fn foo_recursive(&self, n: usize) -> i32 { //~^ ERROR recursion in an async fn requires boxing if n > 0 { self.foo_recursive(n - 1).await } else { *self } } } fn main() {}