error[E0658]: the target feature `apxf` is currently unstable
  --> $DIR/feature-gate-apx-target-feature.rs:2:18
   |
LL | #[target_feature(enable = "apxf")]
   |                  ^^^^^^^^^^^^^^^
   |
   = note: see issue #139284 <https://github.com/rust-lang/rust/issues/139284> for more information
   = help: add `#![feature(apx_target_feature)]` 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   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date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 1 previous error

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