error[E0658]: #[alloc_error_handler] is an unstable feature (see issue #51540)
  --> $DIR/feature-gate-alloc-error-handler.rs:18:1
   |
LL | #[alloc_error_handler] //~ ERROR #[alloc_error_handler] is an unstable feature (see issue #51540)
   | ^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: add #![feature(alloc_error_handler)] to the crate attributes to enable

error: aborting due to previous error

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