error[E0658]: `macro_rules!` derives are unstable --> $DIR/feature-gate-macro-derive.rs:3:1 | LL | macro_rules! MyDerive { derive() {} => {} } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #143549 for more information = help: add `#![feature(macro_derive)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0658`.