NullPointerException on CtParameterReferenceImpl.getDeclaration(CtParameterReferenceImpl.java:44)

[arnobl]

Using the latest 5.2-SNAPSHOT (20160626) version I have a NPE (it was not the case some days ago).

java.lang.NullPointerException
    at spoon.support.reflect.reference.CtParameterReferenceImpl.getDeclaration(CtParameterReferenceImpl.java:44)
    at spoon.support.reflect.reference.CtParameterReferenceImpl.getDeclaration(CtParameterReferenceImpl.java:27)
    at fr.inria.diverse.torgen.inspectorguidget.filter.LocalVariableAccessFilter.matches(LocalVariableAccessFilter.java:15)
    at fr.inria.diverse.torgen.inspectorguidget.filter.LocalVariableAccessFilter.matches(LocalVariableAccessFilter.java:1)

My code is:

    @Override
    public boolean matches(final CtVariableReference<?> element) {
        return element.getDeclaration() instanceof CtLocalVariable;
    }

I think that the problem is the clone method of CtParameterReferenceImpl does not consider the executable parameter, so that it can become null in some cases.

The code I analyse is (it concerns the local var e):

class Foo {
    public void foo() {
        JButton b = new JButton();
        b.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                switch(e.getActionCommand()) {
                }
            }
        });
    }
}

[arnobl]

There may be a problem in the class CtParameterReferenceImpl: the method setDeclaringExecutable can set the executable to null but the method getDeclaration does not check the nullity of executable.

[arnobl]

I checked that the problem does not appear using 5.2.0-20160616.235102-85

[GerardPaligot]

Do you have any test case who highlight your bug? Because I can't reproduce it.

I create a file with your snippet code (Foo class), I apply Spoon on it in no classpath mode and I execute a Query on each CtVariableReference:

@Test
public void testDeclarationOfVariableReference() throws Exception {
    final Launcher launcher = new Launcher();
    launcher.addInputResource("./src/test/resources/noclasspath/Foo2.java");
    launcher.getEnvironment().setNoClasspath(true);
    launcher.buildModel();

    launcher.getModel().getElements(new TypeFilter<CtVariableReference>(CtVariableReference.class) {
        @Override
        public boolean matches(CtVariableReference element) {
            try {
                if (element.getDeclaration() instanceof CtLocalVariable) {

                }
            } catch (NullPointerException e) {
                fail("Fail with " + element.getSimpleName() + " declared in " + element.getParent().getSignature());
            }
            return super.matches(element);
        }
    });
}

But everything works.

[arnobl]

I tried to isolate the problem in a test case but it also works. However, my tool does not work anymore. I will try to find the reason ASAP.

[GerardPaligot]

Ok, the test doesn't work if I change it to:

if (element.clone().getDeclaration() instanceof CtLocalVariable) {
}

There is a bug in the clone. PR soon to fix it.