error[E0119]: conflicting implementations of trait `UniquePtrTarget` for type `here::C`
  --> tests/ui/unique_ptr_twice.rs:16:5
   |
7  |     impl UniquePtr<C> {}
   |     ---------------- first implementation here
...
16 |     impl UniquePtr<C> {}
   |     ^^^^^^^^^^^^^^^^ conflicting implementation for `here::C`