warning: use of deprecated attribute `plugin`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
  --> $DIR/issue-40001.rs:6:1
   |
LL | #![plugin(issue_40001_plugin)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: may be removed in a future compiler version
   |
   = note: `#[warn(deprecated)]` on by default