1 error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
2 --> $DIR/expand-to-unstable-2.rs:10:10
4 LL | #[derive(Unstable)]
7 = note: this error originates in the derive macro `Unstable` (in Nightly builds, run with -Z macro-backtrace for more info)
9 error: aborting due to previous error