GROOVY-8096 setScriptBaseClass with Java class breaks @Field Binding init due to call to super() instead of super(Binding)

[kreiger]

This test fails because ClassNode.getSuperClass().getDeclaredConstructor(SCRIPT_CONTEXT_CTOR) doesn't see the constructors in the Java base class.

ModuleNode.setScriptBaseClassFromConfig(ClassNode)
calls .setSuperClass(ClassHelper.make(baseClassName)) on the scriptDummy ClassNode.

The ClassNode created for this script's base class has .lazyInitDone = true and .constructors = null so when .getSuperClass().getDeclaredConstructor(SCRIPT_CONTEXT_CTOR) is called by ModuleNode.createStatementsClass(), then ClassNode.constructors is set to an empty ArrayList in ClassNode.getDeclaredConstructors()

The script constructor is then generated as

     Constructor(Binding context) {
         super();                   // Fields are initialized after the call to super()
                                    // Fields are initialized here
         setBinding(context);       // Fields are initialized before the call to setBinding(context)
     }

instead of

     Constructor(Binding context) {
         super(context);            // Fields are initialized after the call to super(context)
     }

Fields are initialized between the call to super() and the setBinding(context)
which means Field initializers don't have access to the Binding context.

This leads to MissingPropertyException because we're trying to look up variables from the new Binding() created in the default constructor, instead of the binding we passed in.

[daniellansun]

How about making the default constructor private? Developers can get compilation error other than runtime error, then the program will be more robust IMO.

[kreiger]

Unfortunately the exact same super() call is generated, because classNode.getSuperClass().getDeclaredConstructor(SCRIPT_CONTEXT_CTOR) incorrectly returns null in ModuleNode.createStatementsClass() even though that constructor exists.

If i make the default constructor private i get IllegalAccessError:

java.lang.reflect.InvocationTargetException
    at TestBindingsInFieldInitializersWithConfigJavaBaseScript.main(TestBindingsInFieldInitializersWithConfigJavaBaseScript.groovy)
Caused by: java.lang.IllegalAccessError: tried to access method groovy.lang.BindingScript.<init>()V from class TestBindingsInFieldInitializersWithConfigJavaBaseScript
    at TestBindingsInFieldInitializersWithConfigJavaBaseScript.<init>(TestBindingsInFieldInitializersWithConfigJavaBaseScript.groovy)

If i remove the default constructor i get NoSuchMethodError:

java.lang.reflect.InvocationTargetException
    at TestBindingsInFieldInitializersWithConfigJavaBaseScript.main(TestBindingsInFieldInitializersWithConfigJavaBaseScript.groovy)
Caused by: java.lang.NoSuchMethodError: groovy.lang.BindingScript: method <init>()V not found
    at TestBindingsInFieldInitializersWithConfigJavaBaseScript.<init>(TestBindingsInFieldInitializersWithConfigJavaBaseScript.groovy)

[kreiger]

If i remove both constructors the super() call just goes to the default constructor in groovy.lang.Script, giving MissingPropertyException on trying to access the wrong Binding context on field initalization:

groovy.lang.MissingPropertyException: No such property: args for class: TestBindingsInFieldInitializersWithConfigJavaBaseScript
    at TestBindingsInFieldInitializersWithConfigJavaBaseScript.<init>(TestBindingsInFieldInitializersWithConfigJavaBaseScript.groovy:2)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at groovy.lang.GroovyShell.runScriptOrMainOrTestOrRunnable(GroovyShell.java:271)

[kreiger]

Created JIRA ticket at https://issues.apache.org/jira/browse/GROOVY-8096

[paulk-asert]

Just to clarify - this isn't a PR designed to fix a problem (although BindingScript might prove useful in a solution) but to illustrate a problem. Correct?

[kreiger]

@paulk-asert Correct, this just adds a couple of unit tests to illustrate the problem. I hope you agree that it's better than just describing it. :)

I was able to make a patch myself where i use Class.forName() to look up the class, but i highly doubt it is correct.