fn main() {
    println!("{:?}", {
        struct S<T>(T); trait Tr { } impl<T> Tr for S<T> { } fn foo<T: std::fmt::Debug>(t: T) -> impl Tr + std::fmt::Debug { S(t) }
    });
}


/* ~~~~=== stderr ===~~~~
   Compiling playground v0.0.1 (file:///playground)
error[E0277]: `main::S<T>` doesn't implement `std::fmt::Debug`
 --> src/main.rs:5:98
  |
5 |         struct S<T>(T); trait Tr { } impl<T> Tr for S<T> { } fn foo<T: std::fmt::Debug>(t: T) -> impl Tr + std::fmt::Debug { S(t) }
  |                                                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ `main::S<T>` cannot be formatted using `:?`; add `#[derive(Debug)]` or manually implement `std::fmt::Debug`
  |
  = help: the trait `std::fmt::Debug` is not implemented for `main::S<T>`
  = note: the return type of a function must have a statically known size

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 ===~~~~

*/