checker/tests/nullness/Issue1712.java

// Test case for Issue 1712
// https://github.com/typetools/checker-framework/issues/1712

abstract class Issue1712 {

  abstract <T> T match(
      Function<? super SubclassA, T> visitA, Function<? super SubclassB, T> visitB);

  class SubclassA extends Issue1712 {
    @Override
    <T> T match(Function<? super SubclassA, T> visitA, Function<? super SubclassB, T> visitB) {
      return visitA.apply(this); // line 11
    }
  }

  class SubclassB extends Issue1712 {
    @Override
    <T> T match(Function<? super SubclassA, T> visitA, Function<? super SubclassB, T> visitB) {
      return visitB.apply(this); // line 18
    }
  }

  abstract class Function<T1, T2> {
    abstract T2 apply(T1 arg);
  }
}