error[E0658]: `cfg(doctest)` is experimental and subject to change
  --> $DIR/feature-gate-cfg_doctest.rs:1:7
   |
LL | #[cfg(doctest)]
   |       ^^^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/62210
   = help: add `#![feature(cfg_doctest)]` to the crate attributes to enable

error: aborting due to previous error

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