error[E0658]: attributes of the form `#[derive_*]` are reserved for the compiler (see issue #29644)
  --> $DIR/feature-gate-custom_derive.rs:11:3
   |
LL | #[derive_Clone]
   |   ^^^^^^^^^^^^
   |
   = help: add #![feature(custom_derive)] to the crate attributes to enable

error: aborting due to previous error

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