error[E0277]: the `?` operator can only be used on `Result`s, not `Option`s, in a function that returns `Result`
  --> $DIR/option-to-result.rs:5:6
   |
LL | / fn test_result() -> Result<(),()> {
LL | |     let a:Option<()> = Some(());
LL | |     a?;
   | |      ^ use `.ok_or(...)?` to provide an error compatible with `Result<(), ()>`
LL | |     Ok(())
LL | | }
   | |_- this function returns a `Result`
   |
   = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<(), ()>`

error[E0277]: the `?` operator can only be used on `Option`s, not `Result`s, in a function that returns `Option`
  --> $DIR/option-to-result.rs:11:6
   |
LL | / fn test_option() -> Option<i32>{
LL | |     let a:Result<i32, i32> = Ok(5);
LL | |     a?;
   | |      ^ use `.ok()?` if you want to discard the `Result<Infallible, i32>` error information
LL | |     Some(5)
LL | | }
   | |_- this function returns an `Option`
   |
   = help: the trait `FromResidual<Result<Infallible, i32>>` is not implemented for `Option<i32>`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.
