#![allow(unreachable_code)]


fn main() {
    println!("{:?}", {
        trait AnyDebug { fn as_debug(&self) -> Option<&dyn std::fmt::Debug> { None } } #[derive(Debug)] struct S; impl AnyDebug for S { fn as_debug(&self) -> Option<&dyn std::fmt::Debug> { Some(self) } } let b: Box<dyn AnyDebug> = Box::new(S); println!("{:?}", b.as_debug().unwrap()); struct S2; let b: Box<dyn AnyDebug> = Box::new(S2); println!("{:?}", b.as_debug());
    });
}


/* ~~~~=== stderr ===~~~~
   Compiling playground v0.0.1 (/playground)
error[E0277]: the trait bound `main::S2: main::AnyDebug` is not satisfied
 --> src/main.rs:6:324
  |
6 |         trait AnyDebug { fn as_debug(&self) -> Option<&dyn std::fmt::Debug> { None } } #[derive(Debug)] struct S; impl AnyDebug for S { fn as_debug(&self) -> Option<&dyn std::fmt::Debug> { Some(self) } } let b: Box<dyn AnyDebug> = Box::new(S); println!("{:?}", b.as_debug().unwrap()); struct S2; let b: Box<dyn AnyDebug> = Box::new(S2); println!("{:?}", b.as_debug());
  |                                                                                                                                                                                                                                                                                                                                    ^^^^^^^^^^^^ the trait `main::AnyDebug` is not implemented for `main::S2`
  |
  = note: required for the cast to the object type `dyn main::AnyDebug`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
error: Could not compile `playground`.

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

*/

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

*/