error[E0658]: box pattern syntax is experimental --> $DIR/feature-gate-box_patterns.rs:2:9 | LL | let box x = Box::new('c'); | ^^^^^ | = note: see issue #29641 for more information = help: add `#![feature(box_patterns)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.