checker/tests/units/Consistency.java

import org.checkerframework.checker.units.qual.Area;
import org.checkerframework.checker.units.qual.Length;
import org.checkerframework.checker.units.qual.km;
import org.checkerframework.checker.units.qual.km2;
import org.checkerframework.checker.units.qual.m;
import org.checkerframework.checker.units.qual.m2;
import org.checkerframework.checker.units.util.UnitsTools;

/**
 * One possible future extension is adding method annotations to check for consistency of arguments.
 * This is not implemented yet; send us a message if you think this would help you!
 *
 * @skip-test
 */
public class Consistency {

  @UnitsSame({0, 1})
  @UnitsProduct({0, 1, -1})
  @Area int calcArea(@Length int width, @Length int height) {
    return width * height;
  }

  void use() {
    @m int m1, m2;
    m1 = UnitsTools.toMeter(5);
    m2 = UnitsTools.toMeter(51);

    @km int km1, km2;
    km1 = UnitsTools.toMeter(5);
    km2 = UnitsTools.toMeter(5);

    @m2 int msq;
    @km2 int kmsq;

    // good
    msq = calcArea(m1, m2);

    // :: bad args
    msq = calcArea(m1, km2);

    // :: bad return
    kmsq = calcArea(m1, m2);

    // good
    kmsq = calcArea(km1, km2);
  }
}