error[E0277]: the trait bound `PartialEqNotEq: Eq` is not satisfied --> $DIR/union-derive-eq.rs:16:5 | LL | #[derive(Eq)] | -- in this derive macro expansion LL | union U2 { LL | a: PartialEqNotEq, | ^^^^^^^^^^^^^^^^^ the trait `Eq` is not implemented for `PartialEqNotEq` | note: required by a bound in `AssertParamIsEq` --> $SRC_DIR/core/src/cmp.rs:LL:COL = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info) help: consider annotating `PartialEqNotEq` with `#[derive(Eq)]` | LL + #[derive(Eq)] LL | struct PartialEqNotEq; | error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.