error[E0658]: the `#[do_not_recommend]` attribute is an experimental feature
  --> $DIR/unstable-feature.rs:4:1
   |
LL | #[do_not_recommend]
   | ^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #51992 <https://github.com/rust-lang/rust/issues/51992> for more information
   = help: add `#![feature(do_not_recommend)]` to the crate attributes to enable

error: aborting due to previous error

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