error[E0277]: the trait bound `&Chars: Trait` is not satisfied
  --> $DIR/suggest-remove-deref-issue-140166.rs:14:26
   |
LL |     format_args!("{:?}", FlatMap(&Chars));
   |                   ----   ^^^^^^^^^^^^^^^ the trait `Trait` is not implemented for `&Chars`
   |                   |
   |                   required by this formatting parameter
   |
   = help: the trait `Trait` is implemented for `Chars`
note: required for `FlatMap<&Chars>` to implement `Debug`
  --> $DIR/suggest-remove-deref-issue-140166.rs:7:16
   |
LL | impl<T: Trait> std::fmt::Debug for FlatMap<T> {
   |         -----  ^^^^^^^^^^^^^^^     ^^^^^^^^^^
   |         |
   |         unsatisfied trait bound introduced here

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0277`.