error[E0658]: use of unstable library feature `autodiff`
  --> $DIR/feature-gate-autodiff-use.rs:13:3
   |
LL | #[autodiff(dfoo, Reverse)]
   |   ^^^^^^^^
   |
   = note: see issue #124509 <https://github.com/rust-lang/rust/issues/124509> for more information
   = help: add `#![feature(autodiff)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error[E0658]: use of unstable library feature `autodiff`
  --> $DIR/feature-gate-autodiff-use.rs:9:5
   |
LL | use std::autodiff::autodiff;
   |     ^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #124509 <https://github.com/rust-lang/rust/issues/124509> for more information
   = help: add `#![feature(autodiff)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: aborting due to 2 previous errors

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