checker/tests/wpi-testchecker/non-annotated/LUBAssignmentTest.java

import org.checkerframework.checker.testchecker.wholeprograminference.qual.Parent;
import org.checkerframework.checker.testchecker.wholeprograminference.qual.Sibling1;
import org.checkerframework.checker.testchecker.wholeprograminference.qual.Sibling2;

public class LUBAssignmentTest {
  // The default type for fields is @DefaultType.
  private static int privateField;
  public static int publicField;

  void assignFieldsToSibling1() {
    privateField = getSibling1();
    publicField = getSibling1();
  }

  static {
    privateField = getSibling2();
    publicField = getSibling2();
  }

  // LUB between @Sibling1 and @Sibling2 is @Parent, therefore the assignments
  // above refine the type of privateField to @Parent.
  void testFields() {
    // :: warning: (argument)
    expectsParent(privateField);
    // :: warning: (argument)
    expectsParent(publicField);
  }

  void expectsParent(@Parent int t) {}

  static @Sibling1 int getSibling1() {
    return 0;
  }

  static @Sibling2 int getSibling2() {
    return 0;
  }

  String lubTest2() {
    if (Math.random() > 0.5) {
      @SuppressWarnings("cast.unsafe")
      @Sibling1 String s = (@Sibling1 String) "";
      return s;
    } else {
      @SuppressWarnings("cast.unsafe")
      @Sibling2 String s = (@Sibling2 String) "";
      return s;
    }
  }
}