checker/tests/nullness/generics/KeyForPolyKeyFor.java

package nullness.generics;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.*;

// test related to issue 429: https://github.com/typetools/checker-framework/issues/429
public class KeyForPolyKeyFor {
  // TODO: Figure out why diamond operator does not work:
  // Map<@KeyFor("dict") String, String> dict = new HashMap<>();
  Map<@KeyFor("dict") String, String> dict = new HashMap<@KeyFor("dict") String, String>();

  void m() {
    Set<@KeyFor("dict") String> s = nounSubset(dict.keySet());

    for (@KeyFor("dict") String noun : nounSubset(dict.keySet())) {}
  }

  // This method's declaration uses no @KeyFor annotations because in addition to being used by the
  // dictionary feature, it is also used by a spell checker that only stores sets of words and does
  // not use the notions of dictionaries, maps or keys.
  Set<@PolyKeyFor String> nounSubset(Set<@PolyKeyFor String> words) {
    return words;
  }
}