error[E0658]: the `#[must_not_suspend]` attribute is an experimental feature --> $DIR/feature-gate-must_not_suspend.rs:3:1 | LL | #[must_not_suspend = "You gotta use Umm's, ya know?"] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #83310 for more information = help: add `#![feature(must_not_suspend)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0658`.