error[E0119]: conflicting implementations of trait `AnotherTrait` for type `D<_>`
  --> $DIR/negative-reasoning.rs:19:1
   |
LL | impl<T: std::fmt::Debug> AnotherTrait for T {}
   | ------------------------------------------- first implementation here
...
LL | impl AnotherTrait for D<OpaqueType> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `D<_>`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0119`.