checker/tests/nullness/KeyForSubtyping.java

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

public class KeyForSubtyping {
  HashMap<String, String> mapA = new HashMap<>();
  HashMap<String, String> mapB = new HashMap<>();
  HashMap<String, String> mapC = new HashMap<>();

  public void testSubtypeAssignments(
      String not_a_key,
      @KeyFor("this.mapA") String a,
      @KeyFor("this.mapB") String b,
      @KeyFor({"this.mapA", "this.mapB"}) String ab) {
    // Try the error cases first, otherwise dataflow will change the inferred annotations on the
    // variables such that a line of code can have an effect on a subsequent line of code. We want
    // each of these tests to be independent.

    // :: error: (assignment)
    ab = a;
    // :: error: (assignment)
    ab = b;
    // :: error: (assignment)
    a = b;
    // :: error: (assignment)
    a = not_a_key;
    // :: error: (assignment)
    b = not_a_key;
    // :: error: (assignment)
    ab = not_a_key;

    // Now try the success cases

    a = ab;
    b = ab;
    not_a_key = ab;
    not_a_key = a;
  }

  public void testDataFlow(
      String not_yet_a_key,
      @KeyFor("this.mapA") String a,
      @KeyFor("this.mapB") String b,
      @KeyFor({"this.mapA", "this.mapB"}) String ab) {
    // Test that when a valid assignment is made, dataflow transfers the
    // KeyFor type qualifier from the right hand side to the left hand side.

    // :: error: (argument)
    method1(not_yet_a_key);
    not_yet_a_key = a;
    method1(not_yet_a_key);

    method1(a);
    // :: error: (argument)
    method1(b);
    method1(ab);

    b = ab;
    method1(b);
  }

  public void testSetOrdering(
      @KeyFor({"this.mapC", "this.mapA"}) String ac,
      @KeyFor({"this.mapA", "this.mapB", "this.mapC"}) String abc) {
    // Test that the order of elements in the set doesn't matter when doing subtyping checks,
    // @KeyFor("A, B, C") <: @KeyFor("C, A")

    // Try the error case first - see the note in method testSubtypeAssignments

    // :: error: (assignment)
    abc = ac;

    ac = abc;
  }

  public void testDataflowTransitivity(
      @KeyFor({"this.mapA"}) String a,
      @KeyFor({"this.mapA", "this.mapB"}) String ab,
      @KeyFor({"this.mapA", "this.mapB", "this.mapC"}) String abc) {
    ab = abc;
    // At this point, dataflow should have refined the type of ab to
    // @KeyFor({"this.mapA","this.mapB","this.mapC"})
    a = ab;
    // At this point, dataflow should have refined the type of a to
    // @KeyFor({"this.mapA","this.mapB","this.mapC"})

    // This would not succeed without the previous two assignments, but should now because of
    // dataflow.
    abc = a;
  }

  private void method1(@KeyFor("this.mapA") String a) {}

  private void testWithNullnessAnnotation(
      String not_a_key,
      @KeyFor("this.mapA") String a,
      @KeyFor("this.mapB") String b,
      @Nullable @KeyFor({"this.mapA", "this.mapB"}) String ab) {
    // These fail only because a @Nullable RHS cannot be assigned to a @NonNull LHS.

    // :: error: (assignment)
    a = ab;
    // :: error: (assignment)
    b = ab;
    // :: error: (assignment)
    not_a_key = ab;

    not_a_key = a; // Succeeds because both sides are @NonNull
  }

  // Test overriding

  static class Super {
    HashMap<String, String> map1 = new HashMap<>();
    HashMap<String, String> map2 = new HashMap<>();

    void method1(@KeyFor({"this.map1", "this.map2"}) String s) {}

    void method2(@KeyFor("this.map1") String s) {}
  }

  static class Sub extends Super {
    @Override
    void method1(@KeyFor("this.map1") String s) {}

    @Override
    // :: error: (override.param)
    void method2(@KeyFor({"this.map1", "this.map2"}) String s) {}
  }
}