error[E0277]: the trait bound `Error: Default` is not satisfied --> $DIR/derives-span-Default-struct.rs:8:5 | LL | #[derive(Default)] | ------- in this derive macro expansion LL | struct Struct { LL | x: Error | ^^^^^^^^ the trait `Default` is not implemented for `Error` | = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info) help: consider annotating `Error` with `#[derive(Default)]` | LL | #[derive(Default)] | error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.