// edition:2018 // compile-flags: -Zdrop-tracking #![feature(must_not_suspend)] #![deny(must_not_suspend)] #[must_not_suspend = "You gotta use Umm's, ya know?"] struct Umm { i: i64 } struct Bar { u: Umm, } async fn other() {} impl Bar { async fn uhoh(&mut self) { let guard = &mut self.u; //~ ERROR `Umm` held across other().await; *guard = Umm { i: 2 } } } fn main() { }