TestFlow.java

import org.checkerframework.checker.fenum.qual.Fenum;

@SuppressWarnings("fenum:assignment.type.incompatible")
public class TestFlow {
    public final @Fenum("A") Object ACONST1 = new Object();

    public final @Fenum("B") Object BCONST1 = new Object();
}

class FenumUser {

    @Fenum("A") Object state1 = new TestFlow().ACONST1;

    void foo(TestFlow t) {
        //:: error: (method.invocation.invalid)
        state1.hashCode();
        state1 = null;
        state1.hashCode();
        m();
        //:: error: (method.invocation.invalid)
        state1.hashCode();

        Object o = new Object();
        o = t.ACONST1;
        methodA(o);
        //:: error: (argument.type.incompatible)
        methodB(o);

        o = t.BCONST1;
        //:: error: (argument.type.incompatible)
        methodA(o);
        methodB(o);
    }

    void m() {}

    void methodA(@Fenum("A") Object a) {}

    void methodB(@Fenum("B") Object a) {}
}