error[E0004]: non-exhaustive patterns: `(Some(&[]), Err(_))` not covered --> $DIR/non-exhaustive-match-nested.rs:5:11 | LL | match (l1, l2) { | ^^^^^^^^ pattern `(Some(&[]), Err(_))` not covered | = note: the matched value is of type `(Option<&[T]>, Result<&[T], ()>)` help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown | LL ~ (None, Ok(&[_, _, ..])) => "None, Ok(at least two elements)", LL + (Some(&[]), Err(_)) => todo!() | error[E0004]: non-exhaustive patterns: `T::A(U::C)` not covered --> $DIR/non-exhaustive-match-nested.rs:15:11 | LL | match x { | ^ pattern `T::A(U::C)` not covered | note: `T` defined here --> $DIR/non-exhaustive-match-nested.rs:1:10 | LL | enum T { A(U), B } | - ^ not covered = note: the matched value is of type `T` help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown | LL ~ T::B => { panic!("goodbye"); }, LL + T::A(U::C) => todo!() | error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0004`.