|  | error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `Try`) | 
|  | --> $DIR/try-on-option-diagnostics.rs:7:5 | 
|  | | | 
|  | LL | / fn a_function() -> u32 { | 
|  | LL | |     let x: Option<u32> = None; | 
|  | LL | |     x?; | 
|  | | |     ^^ cannot use the `?` operator in a function that returns `u32` | 
|  | LL | |     22 | 
|  | LL | | } | 
|  | | |_- this function should return `Result` or `Option` to accept `?` | 
|  | | | 
|  | = help: the trait `Try` is not implemented for `u32` | 
|  | = note: required by `from_error` | 
|  |  | 
|  | error[E0277]: the `?` operator can only be used in a closure that returns `Result` or `Option` (or another type that implements `Try`) | 
|  | --> $DIR/try-on-option-diagnostics.rs:14:9 | 
|  | | | 
|  | LL |       let a_closure = || { | 
|  | |  _____________________- | 
|  | LL | |         let x: Option<u32> = None; | 
|  | LL | |         x?; | 
|  | | |         ^^ cannot use the `?` operator in a closure that returns `{integer}` | 
|  | LL | |         22 | 
|  | LL | |     }; | 
|  | | |_____- this function should return `Result` or `Option` to accept `?` | 
|  | | | 
|  | = help: the trait `Try` is not implemented for `{integer}` | 
|  | = note: required by `from_error` | 
|  |  | 
|  | error[E0277]: the `?` operator can only be used in a method that returns `Result` or `Option` (or another type that implements `Try`) | 
|  | --> $DIR/try-on-option-diagnostics.rs:26:13 | 
|  | | | 
|  | LL | /         fn a_method() { | 
|  | LL | |             let x: Option<u32> = None; | 
|  | LL | |             x?; | 
|  | | |             ^^ cannot use the `?` operator in a method that returns `()` | 
|  | LL | |         } | 
|  | | |_________- this function should return `Result` or `Option` to accept `?` | 
|  | | | 
|  | = help: the trait `Try` is not implemented for `()` | 
|  | = note: required by `from_error` | 
|  |  | 
|  | error[E0277]: the `?` operator can only be used in a trait method that returns `Result` or `Option` (or another type that implements `Try`) | 
|  | --> $DIR/try-on-option-diagnostics.rs:39:13 | 
|  | | | 
|  | LL | /         fn a_trait_method() { | 
|  | LL | |             let x: Option<u32> = None; | 
|  | LL | |             x?; | 
|  | | |             ^^ cannot use the `?` operator in a trait method that returns `()` | 
|  | LL | |         } | 
|  | | |_________- this function should return `Result` or `Option` to accept `?` | 
|  | | | 
|  | = help: the trait `Try` is not implemented for `()` | 
|  | = note: required by `from_error` | 
|  |  | 
|  | error: aborting due to 4 previous errors | 
|  |  | 
|  | For more information about this error, try `rustc --explain E0277`. |