fn main() {
    println!("{:?}", {
        fn foo(a: Option<i32>, b: Option<i32>) -> Option<i32> { let c = (|| a? + b?); c }
    });
}


/* ~~~~=== stderr ===~~~~
   Compiling playground v0.0.1 (file:///playground)
warning: unnecessary parentheses around assigned value
 --> src/main.rs:5:73
  |
5 |         fn foo(a: Option<i32>, b: Option<i32>) -> Option<i32> { let c = (|| a? + b?); c }
  |                                                                         ^^^^^^^^^^^^ help: remove these parentheses
  |
  = note: #[warn(unused_parens)] on by default

error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)
 --> src/main.rs:5:77
  |
5 |         fn foo(a: Option<i32>, b: Option<i32>) -> Option<i32> { let c = (|| a? + b?); c }
  |                                                                             ^^ cannot use the `?` operator in a function that returns `i32`
  |
  = help: the trait `std::ops::Try` is not implemented for `i32`
  = note: required by `std::ops::Try::from_error`

error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)
 --> src/main.rs:5:82
  |
5 |         fn foo(a: Option<i32>, b: Option<i32>) -> Option<i32> { let c = (|| a? + b?); c }
  |                                                                                  ^^ cannot use the `?` operator in a function that returns `i32`
  |
  = help: the trait `std::ops::Try` is not implemented for `i32`
  = note: required by `std::ops::Try::from_error`

error[E0308]: mismatched types
 --> src/main.rs:5:87
  |
5 |         fn foo(a: Option<i32>, b: Option<i32>) -> Option<i32> { let c = (|| a? + b?); c }
  |                                                   -----------                         ^ expected enum `std::option::Option`, found closure
  |                                                   |
  |                                                   expected `std::option::Option<i32>` because of return type
  |
  = note: expected type `std::option::Option<i32>`
             found type `[closure@src/main.rs:5:73: 5:85 a:_, b:_]`

error: aborting due to 3 previous errors

Some errors occurred: E0277, E0308.
For more information about an error, try `rustc --explain E0277`.
error: Could not compile `playground`.

To learn more, run the command again with --verbose.

*/

/* ~~~~=== stdout ===~~~~

*/