error[E0658]: `cfg(overflow_checks)` is experimental and subject to change --> $DIR/feature-gate-cfg_overflow_checks.rs:3:7 | LL | #[cfg(overflow_checks)] | ^^^^^^^^^^^^^^^ | = note: see issue #111466 for more information = help: add `#![feature(cfg_overflow_checks)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.