error[E0658]: const closures are experimental --> $DIR/gate.rs:3:6 | LL | (const || {})(); | ^^^^^^^^^^^ | = note: see issue #106003 for more information = help: add `#![feature(const_closures)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.