error[E0412]: cannot find type `MissingType` in this scope
  --> $DIR/issue-68830-spurious-diagnostics.rs:8:10
   |
LL |     err: MissingType
   |          ^^^^^^^^^^^ not found in this scope

error[E0119]: conflicting implementations of trait `MyTrait<_>` for type `BadStruct`
  --> $DIR/issue-68830-spurious-diagnostics.rs:19:1
   |
LL | impl<T, D> MyTrait<T> for D {
   | --------------------------- first implementation here
...
LL | impl<T> MyTrait<T> for BadStruct {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `BadStruct`

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0119, E0412.
For more information about an error, try `rustc --explain E0119`.