framework/tests/all-systems/PolyCollectorTypeVars.java

import java.util.Comparator;

class MyGen<K0> {}

abstract class Ordering<T> implements Comparator<T> {
  // Natural order

  public static <C extends Comparable> Ordering<C> natural() {
    return new Ordering<C>() {
      @Override
      public int compare(C o1, C o2) {
        return 0;
      }
    };
  }
}

public class PolyCollectorTypeVars {
  // Both of these come from the extends Comparable on line 9
  @SuppressWarnings({"rawtypes", "type.argument"})
  public static MyGen<Comparable> treeKeys2() {
    // See Limitation in DefaultTypeArgumentInference on interdependent methods
    return treeKeys(Ordering.natural());
  }

  public static <K0> MyGen<K0> treeKeys(final Comparator<K0> comparator) {
    return new MyGen<K0>();
  }
}