error[E0658]: the `#[optimize]` attribute is an experimental feature
  --> $DIR/feature-gate-optimize_attribute.rs:2:1
   |
LL | #![optimize(speed)]
   | ^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
   = help: add `#![feature(optimize_attribute)]` 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   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date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]: the `#[optimize]` attribute is an experimental feature
  --> $DIR/feature-gate-optimize_attribute.rs:4:1
   |
LL | #[optimize(size)]
   | ^^^^^^^^^^^^^^^^^
   |
   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
   = help: add `#![feature(optimize_attribute)]` 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   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date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]: the `#[optimize]` attribute is an experimental feature
  --> $DIR/feature-gate-optimize_attribute.rs:7:1
   |
LL | #[optimize(size)]
   | ^^^^^^^^^^^^^^^^^
   |
   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
   = help: add `#![feature(optimize_attribute)]` 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   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date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]: the `#[optimize]` attribute is an experimental feature
  --> $DIR/feature-gate-optimize_attribute.rs:10:1
   |
LL | #[optimize(speed)]
   | ^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
   = help: add `#![feature(optimize_attribute)]` 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   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date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]: the `#[optimize]` attribute is an experimental feature
  --> $DIR/feature-gate-optimize_attribute.rs:13:1
   |
LL | #[optimize(banana)]
   | ^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
   = help: add `#![feature(optimize_attribute)]` 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   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date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[E0722]: invalid argument
  --> $DIR/feature-gate-optimize_attribute.rs:13:12
   |
LL | #[optimize(banana)]
   |            ^^^^^^

error: aborting due to 6 previous errors

Some errors have detailed explanations: E0658, E0722.
For more information about an error, try `rustc --explain E0658`.