error[E0658]: this is an internal attribute that will never be stable --> $DIR/gate-do-not-const-check.rs:1:1 | LL | #[rustc_do_not_const_check] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0658`.