This program fails to compile:

import java.util.ArrayList;

enum Day {
    Sunday,
    Monday,
    Tuesday
};

public class X {
    public static void main(String [] args) {
        Day day = null;
        
        switch (day) {
            case Sunday: break;
            case Monday: break;
        }

        if (day __matches Sunday) {
            System.out.println("Blah");
        }
    }
}

X.java:18: error: cannot find symbol
        if (day __matches Sunday) {
                          ^
  symbol: variable Sunday
  location: class X
1 error