error[E0658]: use of an internal attribute
  --> $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
   = note: the `#[rustc_do_not_const_check]` attribute is an internal implementation detail that will never be stable
   = note: `#[rustc_do_not_const_check]` skips const-check for this function's body

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0658`.