[GROOVY-7866] Groovy tries to invoke an instance method in a static context when using ExpandoMetaClass

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.4.7
• Labels: trait traits
• Assignee: Unassigned
• Reporter: Graeme Rocher
• Created: 17/Jun/16 08:35
• Updated: 17/Oct/21 15:43

Description

The following script:

ExpandoMetaClass.enableGlobally()

trait Attributes {
    void attributes(Map attrs) {}
}    

class Foo implements Attributes {
    String attributes
    static stuff = {
        attributes foo:"bar"
    }
}

new Foo().attributes(foo:'bar')

Foo.stuff.call()

Produces

java.lang.IllegalArgumentException: object is not an instance of declaring class
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
	at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1212)
	at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:1125)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1021)
	at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1157)

I debugged the issue and there is some kind of caching logic that is broken. There is a `CachedMethod` instance that is invoked, even though it is not a static method.

There should never be a case where the `attributes` method from the trait is invoked since it is an instance method and this is a static context.