error[E0277]: the trait bound `T: Trait` is not satisfied
  --> $DIR/underconstrained_generic.rs:22:5
   |
LL |     ()
   |     ^^ the trait `Trait` is not implemented for `T`
   |
note: required for `()` to implement `ProofForConversion<T>`
  --> $DIR/underconstrained_generic.rs:13:16
   |
LL | impl<X: Trait> ProofForConversion<X> for () {
   |         -----  ^^^^^^^^^^^^^^^^^^^^^     ^^
   |         |
   |         unsatisfied trait bound introduced here
help: consider restricting type parameter `T`
   |
LL | type Converter<T: Trait> = impl ProofForConversion<T>;
   |                 +++++++

error: aborting due to previous error

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