error[E0277]: `Error` doesn't implement `Debug` --> $DIR/derives-span-Debug-struct.rs:8:5 | LL | #[derive(Debug)] | ----- in this derive macro expansion LL | struct Struct { LL | x: Error | ^^^^^^^^ `Error` cannot be formatted using `{:?}` | = help: the trait `Debug` is not implemented for `Error` = note: add `#[derive(Debug)]` to `Error` or manually `impl Debug for Error` = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info) help: consider annotating `Error` with `#[derive(Debug)]` | LL | #[derive(Debug)] | error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.