fn main() {
    println!("{:?}", {
        #[derive(Debug)] struct S<T>(T); trait Tr { } impl<T> Tr for S<T> { } fn foo<T>(t: T) -> impl Tr { S(t) } foo(5)
    });
}


/* ~~~~=== stderr ===~~~~
   Compiling playground v0.0.1 (file:///playground)
error[E0277]: `impl main::Tr` doesn't implement `std::fmt::Debug`
 --> src/main.rs:4:22
  |
4 |       println!("{:?}", {
  |  ______________________^
5 | |         #[derive(Debug)] struct S<T>(T); trait Tr { } impl<T> Tr for S<T> { } fn foo<T>(t: T) -> impl Tr { S(t) } foo(5)
6 | |     });
  | |_____^ `impl main::Tr` cannot be formatted using `:?` because it doesn't implement `std::fmt::Debug`
  |
  = help: the trait `std::fmt::Debug` is not implemented for `impl main::Tr`
  = note: required by `std::fmt::Debug::fmt`

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 ===~~~~

*/