error[E0369]: binary operation `==` cannot be applied to type `Error` --> $DIR/derives-span-PartialEq-enum.rs:9:6 | LL | #[derive(PartialEq)] | --------- in this derive macro expansion ... LL | Error | ^^^^^ | note: an implementation of `PartialEq<_>` might be missing for `Error` --> $DIR/derives-span-PartialEq-enum.rs:4:1 | LL | struct Error; | ^^^^^^^^^^^^ must implement `PartialEq<_>` = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info) help: consider annotating `Error` with `#[derive(PartialEq)]` | LL + #[derive(PartialEq)] LL | struct Error; | error: aborting due to previous error For more information about this error, try `rustc --explain E0369`.