Truffle: [NodeUtil.findFirstNodeInstance(..) + SpecializationNode.next]: NullPointerException!!

[Christian Humer]

Thanks! From the error you sent me it looks like a null value assigned to a 
field similar to: @Children Node[] childrenField

btw.: You don't need @CompilationFinal if your field is already annotated with 
@Child. @Child implies @CompilationFinal implicitely.

- Christian Humer


"Mohaned Y Qunaibit" <mqunaibi at uci.edu> wrote:
> Hello Christian,
> Yes, you are right it's not related to the ; it's one of the children from a 
> parent class:
> The work around I used for now is use  instead.
> I will try to find a way to create a small example after I fully find the 
> root of the issue.
>> On Sun, Jun 7, 2015 at 10:08 AM, Christian Humer 
>> <[christian.humer at gmail.com](mailto:christian.humer at gmail.com)> wrote: 
>>  
>> Hi Mohaned, 
>>  
>> I am not sure its related to the next pointer. Can you provide me with some 
>> some test code that I can run as well as the full stack trace? 
>>  
>> My first guess would be that you have a field annotated with @Children that 
>> is null. Can you also show me the code of the node that is responsible for 
>> the error? 
>>  
>> Anyway I think nodeAt should be more robust with null values in fields 
>> annotated with @Children. Will discuss this in the meantime. 
>>  
>> Thanks. 
>>  
>> - Christian Humer 
>>  
>> "Mohaned Y Qunaibit" <[mqunaibi at uci.edu](mailto:mqunaibi at uci.edu)> wrote: 
>>  
>> Hi, 
>>  
>>  
>> While I was merging the new changes on Graal+Truffle for ZipPy, I got null 
>>  
>> pointer exception when calling NodeUtil.findFirstNodeInstance(..) function. 
>>  
>>  
>> The problem is related to the SpecializationNode.next child. Since next is 
>>  
>> the only child of the uninitialized node NodeClass().getChildren() returns 
>>  
>> a list with null child and cause this issue. 
>>  
>>  
>> More specifically when fetching 
>>  
>> *childFields[0].getObject(UninitializedNode_);* 
>>  
>> NodeClass.java: 215 
>>  
>> private Node nodeAt(int idx) { 
>>  
>> int nodeCount = childFields.length; 
>>  
>> if (idx < nodeCount) { 
>>  
>> return (Node) *childFields[idx].getObject(node);* 
>>  
>> } else { 
>>  
>> for (NodeFieldAccessor childrenField : childrenFields) { 
>>  
>> Object[] nodeArray = (Object[]) 
>>  
>> childrenField.getObject(node); 
>>  
>> if (idx < nodeCount + nodeArray.length) { 
>>  
>> return (Node) nodeArray[idx - nodeCount]; 
>>  
>> } 
>>  
>> nodeCount += nodeArray.length; 
>>  
>> } 
>>  
>> } 
>>  
>> return null; 
>>  
>> } 
>>  
>>  
>> Any idea on how to fix/avoid it? 
>>  
>>  
>> Best, 
>>  
>> Mohaned Qunaibit