error[E0277]: `U` doesn't implement `std::fmt::Debug`
  --> $DIR/generic_underconstrained2.rs:5:1
   |
LL | existential type Underconstrained<T: std::fmt::Debug>: 'static;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `U` cannot be formatted using `{:?}` because it doesn't implement `std::fmt::Debug`
   |
   = help: the trait `std::fmt::Debug` is not implemented for `U`
   = help: consider adding a `where U: std::fmt::Debug` bound
   = note: the return type of a function must have a statically known size

error[E0277]: `V` doesn't implement `std::fmt::Debug`
  --> $DIR/generic_underconstrained2.rs:13:1
   |
LL | existential type Underconstrained2<T: std::fmt::Debug>: 'static;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `V` cannot be formatted using `{:?}` because it doesn't implement `std::fmt::Debug`
   |
   = help: the trait `std::fmt::Debug` is not implemented for `V`
   = help: consider adding a `where V: std::fmt::Debug` bound
   = note: the return type of a function must have a statically known size

error: aborting due to 2 previous errors

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