error[E0277]: can't compare `Comparable` with `Comparable`
  --> $DIR/invalid-derive-comparison-34229.rs:2:46
   |
LL | #[derive(PartialEq, PartialOrd)] struct Nope(Comparable);
   |                     ----------               ^^^^^^^^^^ no implementation for `Comparable < Comparable` and `Comparable > Comparable`
   |                     |
   |                     in this derive macro expansion
   |
   = help: the trait `PartialOrd` is not implemented for `Comparable`
help: consider annotating `Comparable` with `#[derive(PartialOrd)]`
   |
LL | #[derive(PartialEq)] #[derive(PartialOrd)]
   |                      +++++++++++++++++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.
