error[E0658]: compiler plugins are experimental and possibly buggy
  --> $DIR/feature-gate-plugin.rs:3:1
   |
LL | #![plugin(foo)]
   | ^^^^^^^^^^^^^^^
   |
   = note: for more information, see https://github.com/rust-lang/rust/issues/29597
   = help: add #![feature(plugin)] to the crate attributes to enable

error: aborting due to previous error

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