error[E0658]: async closures are unstable --> $DIR/feature-async-closure.rs:5:13 | LL | let _ = async || {}; | ^^^^^ | = note: see issue #62290 for more information = help: add `#![feature(async_closure)]` to the crate attributes to enable = help: to use an async block, remove the `||`: `async {` error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.