src/test/ui/feature-gate-rustc_const_unstable.stderr

error[E0658]: the `#[rustc_const_unstable]` attribute is an internal feature
  --> $DIR/feature-gate-rustc_const_unstable.rs:18:1
   |
18 | #[rustc_const_unstable(feature="fzzzzzt")] //~ERROR internal feature
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: add #![feature(rustc_const_unstable)] to the crate attributes to enable

error: aborting due to previous error