use tests_build::tokio; #[tokio::main] async fn never() -> ! { loop {} } #[tokio::main] async fn impl_trait() -> impl Iterator { [()].into_iter() } #[tokio::main] async fn impl_trait2() -> Result<(), impl core::fmt::Debug> { Err(()) } fn main() { if impl_trait().count() == 10 { never(); } let _ = impl_trait2(); }