error[E0308]: `?` operator has incompatible types --> $DIR/remove-question-symbol-with-paren.rs:5:6 | LL | fn foo() -> Option<()> { | ---------- expected `Option<()>` because of return type LL | let x = Some(()); LL | (x?) | ^^ expected `Option<()>`, found `()` | = note: `?` operator cannot convert from `()` to `Option<()>` = note: expected enum `Option<()>` found unit type `()` help: try removing this `?` | LL - (x?) LL + (x) | help: try wrapping the expression in `Some` | LL | (Some(x?)) | +++++ + error: aborting due to previous error For more information about this error, try `rustc --explain E0308`.