warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/issue-52050.rs:1:12
   |
LL | #![feature(specialization)]
   |            ^^^^^^^^^^^^^^
   |
   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
   = help: consider using `min_specialization` instead, which is more stable and complete
   = note: `#[warn(incomplete_features)]` on by default

error[E0119]: conflicting implementations of trait `IntoPyDictPointer` for type `()`
  --> $DIR/issue-52050.rs:28:1
   |
LL | / impl<I> IntoPyDictPointer for I
LL | | where
LL | |     I: Iterator,
   | |________________- first implementation here
...
LL |   impl IntoPyDictPointer for ()
   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `()`
   |
   = note: upstream crates may add a new impl of trait `std::iter::Iterator` for type `()` in future versions

error: aborting due to 1 previous error; 1 warning emitted

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