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Bug 318899

Summary:	NPE with @args matching Argument by Type
Product:	[Tools] AspectJ	Reporter:	stefan.penndorf
Component:	LTWeaving	Assignee:	aspectj inbox <aspectj-inbox>
Status:	RESOLVED FIXED	QA Contact:
Severity:	major
Priority:	P3	CC:	aclement
Version:	unspecified
Target Milestone:	1.6.10
Hardware:	PC
OS:	All
Whiteboard:

Description stefan.penndorf

2010-07-05 10:24:03 EDT

Build Identifier: 

This bug is related to Bug 257833. I'm wondering why nobody has faced and reported that bug before?!?!

This is the top of the stacktrace i get:
java.lang.NullPointerException
	at org.aspectj.weaver.reflect.ShadowMatchImpl$RuntimeTestEvaluator.visit(ShadowMatchImpl.java:140)
	at org.aspectj.weaver.ast.Instanceof.accept(Instanceof.java:29)
	at org.aspectj.weaver.reflect.ShadowMatchImpl$RuntimeTestEvaluator.matches(ShadowMatchImpl.java:121)
	at org.aspectj.weaver.reflect.ShadowMatchImpl.matchesJoinPoint(ShadowMatchImpl.java:78)

This bug occurs in aspectJ 1.6.1 and 1.6.8 so i think all versions in between are affected as well. I'm using aspectJ together with Spring 2.5.6 but i think that does not matter.

Expected behavior:
When using @Before("args(myId,..)") to match all methods that have an argument of type MyInterface as first argument (see steps to reproduce), the methods declared argument types should be used to determine if the method matches when null is passed as first argument.

Actual Behavior:
NullPointerException is thrown from org.aspectj.weaver.reflect.ShadowMatchImpl$RuntimeTestEvaluator.visit(ShadowMatchImpl.java:140).


Note: Everything works fine if null is not used as first argument. That means if your first argument is never null you'll get no exception and everything works as expected. But if there is one method you don't want to match/intercept that gets null as it's first argument the runtime exception occurs.

Reproducible: Always

Steps to Reproduce:
1. define an interface MyInterface
2. define a pointcut / empty advice using "@args(myId)", e.g.
@Before("args(myId,..)")
public void startsMyIdArgument(final JoinPoint jp, final MyInterface myId) { };
3. call a method of an intercepted class with the first argument being null and you'll get a NullPointerException

Comment 1 Andrew Clement

2010-07-06 15:34:08 EDT

I tried to build a scenario from your instructions, but it just works fine for me.  My code is below - is that the kind of thing you mean?  I haven't used spring in this case, I was hoping to recreate it without needing to do so.

---- B.java ----
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

public class B {
	public static void main(String[] args) {
		new D().foo(null);
	}
}

class D {
	public void foo(MyInterface mi) {
	}
}

@Aspect
class X {
	@Before("args(myId)")
	public void startsMyIdArgument(final JoinPoint jp, final MyInterface myId) {
	}
}

interface MyInterface {
}
----

Comment 2 Andrew Clement

2010-09-01 00:19:38 EDT

created the NPE with a unit test (couldn't create it with a compiler test).  Fixed it up.