| error[E0277]: the trait bound `Error: Eq` is not satisfied | 
 |   --> $DIR/derives-span-Eq-tuple-struct.rs:8:5 | 
 |    | | 
 | LL | #[derive(Eq,PartialEq)] | 
 |    |          -- in this derive macro expansion | 
 | LL | struct Struct( | 
 | LL |     Error | 
 |    |     ^^^^^ the trait `Eq` is not implemented for `Error` | 
 |    | | 
 | note: required by a bound in `AssertParamIsEq` | 
 |   --> $SRC_DIR/core/src/cmp.rs:LL:COL | 
 | help: consider annotating `Error` with `#[derive(Eq)]` | 
 |    | | 
 | LL + #[derive(Eq)] | 
 | LL | struct Error; | 
 |    | | 
 |  | 
 | error: aborting due to 1 previous error | 
 |  | 
 | For more information about this error, try `rustc --explain E0277`. |