error[E0277]: `?` couldn't convert the error to `()` --> $DIR/issue-32709.rs:4:11 | LL | fn a() -> Result<i32, ()> { | --------------- expected `()` because of this LL | Err(5)?; | ^ the trait `From<{integer}>` is not implemented for `()` | = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait = help: the following other types implement trait `FromResidual<R>`: <Result<T, F> as FromResidual<Result<Infallible, E>>> <Result<T, F> as FromResidual<Yeet<E>>> = note: required for `Result<i32, ()>` to implement `FromResidual<Result<Infallible, {integer}>>` error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.