error[E0392]: parameter `T` is never used --> $DIR/E0392.rs:1:10 | LL | enum Foo { Bar } | ^ unused parameter | = help: consider removing `T`, referring to it in a field, or using a marker such as `std::marker::PhantomData` error: aborting due to previous error For more information about this error, try `rustc --explain E0392`.