PureTest.java

import org.checkerframework.checker.nullness.qual.*;
import org.checkerframework.dataflow.qual.*;

class PureTest {
    @org.checkerframework.dataflow.qual.Pure
    @Nullable Object puremethod(@Nullable Object a) {
        return a;
    }

    public void test() {
        //:: error: (assignment.type.incompatible)
        @NonNull Object l0 = puremethod(null);

        if (puremethod(null) == null) {
            //:: error: (assignment.type.incompatible)
            @NonNull Object l1 = puremethod(null);
        }

        if (puremethod("m") != null) {
            @NonNull Object l1 = puremethod("m");
        }

        if (puremethod("m") != null) {
            //:: error: (assignment.type.incompatible)
            @NonNull Object l1 = puremethod(null);
        }

        if (puremethod("m") != null) {
            //:: error: (assignment.type.incompatible)
            @NonNull Object l1 = puremethod("n");
        }

        Object x = new Object();

        if (puremethod(x) == null) {
            return;
        }

        @NonNull Object l2 = puremethod(x);

        x = new Object();

        //:: error: (assignment.type.incompatible)
        @NonNull Object l3 = puremethod(x);

        //:: error: (assignment.type.incompatible)
        @NonNull Object l4 = puremethod("n");
    }

    public @org.checkerframework.dataflow.qual.Pure @Nullable Object getSuperclass() {
        return null;
    }

    static void shortCircuitAnd(PureTest pt) {
        if ((pt.getSuperclass() != null)
                && pt.getSuperclass().toString().equals("java.lang.Enum")) {
            // empty body
        }
    }

    static void shortCircuitOr(PureTest pt) {
        if ((pt.getSuperclass() == null)
                || pt.getSuperclass().toString().equals("java.lang.Enum")) {
            // empty body
        }
    }

    static void testInstanceofNegative(PureTest pt) {
        if (pt.getSuperclass() instanceof Object) {
            return;
        }
        //:: error: (dereference.of.nullable)
        pt.getSuperclass().toString();
    }

    static void testInstanceofPositive(PureTest pt) {
        if (!(pt.getSuperclass() instanceof Object)) {
            return;
        }
        pt.getSuperclass().toString();
    }

    static void testInstanceofPositive2(PureTest pt) {
        if (!(pt.getSuperclass() instanceof Object)) {
        } else {
            pt.getSuperclass().toString();
        }
    }

    static void testInstanceofNegative2(PureTest pt) {
        if (pt.getSuperclass() instanceof Object) {
        } else {
            return;
        }
        pt.getSuperclass().toString();
    }

    static void testInstanceofString(PureTest pt) {
        if (!(pt.getSuperclass() instanceof String)) {
            return;
        }
        pt.getSuperclass().toString();
    }

    static void testContinue(PureTest pt) {
        for (; ; ) {
            if (pt.getSuperclass() == null) {
                System.out.println("m");
                continue;
            }
            pt.getSuperclass().toString();
        }
    }

    void setSuperclass(@Nullable Object no) {
        // set the field returned by getSuperclass.
    }

    static void testInstanceofPositive3(PureTest pt) {
        if (!(pt.getSuperclass() instanceof Object)) {
            return;
        } else {
            pt.setSuperclass(null);
        }
        //:: error: (dereference.of.nullable)
        pt.getSuperclass().toString();
    }

    @Override
    @SideEffectFree
    public String toString() {
        return "foo";
    }
}