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// edition:2018 #![feature(must_not_suspend)] #![deny(must_not_suspend)] #[must_not_suspend = "You gotta use Umm's, ya know?"] struct Umm { i: i64 } fn bar() -> Umm { Umm { i: 1 } } async fn other() {} pub async fn uhoh() { let _guard = bar(); //~ ERROR `Umm` held across other().await; drop(_guard); } fn main() { }