error[E0277]: `()` doesn't implement `std::fmt::Display`
  --> $DIR/issue-81098.rs:3:13
   |
LL | fn wat() -> impl core::fmt::Display {
   |             ^^^^^^^^^^^^^^^^^^^^^^^ `()` cannot be formatted with the default formatter
   |
   = help: the trait `std::fmt::Display` is not implemented for `()`
   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead

error[E0277]: `()` doesn't implement `std::fmt::Display`
  --> $DIR/issue-81098.rs:9:12
   |
LL | fn ok() -> impl core::fmt::Display {
   |            ^^^^^^^^^^^^^^^^^^^^^^^ `()` cannot be formatted with the default formatter
LL |     1;
   |     -- help: remove this semicolon
   |     |
   |     this expression has type `{integer}`, which implements `std::fmt::Display`
   |
   = help: the trait `std::fmt::Display` is not implemented for `()`
   = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead

error: aborting due to 2 previous errors

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