RFR 8186961 Class.getFields() does not return fields of previously visited super interfaces/classes.

[Paul Sandoz]

Here is the updated webrev:

  http://cr.openjdk.java.net/~psandoz/jdk10/JDK-8186961-iface-static-fields-get/webrev/

I opted for the simple solution using a LinkedHashSet.

It’s possible to heavily optimize (avoiding the production of a linked hash set until required [*]) but the resulting code is harder to understand.

Paul.

[*] when there are two or more super interface with fields, or one or more super interfaces and a super classes with fields.


> On 30 Nov 2017, at 08:41, Paul Sandoz <Paul.Sandoz at oracle.com> wrote:
> 
> Hi Caes,
> 
> As we discussed off list the post loop logic is easily missed.
> 
> However, i found another obvious issue i missed with two classes (super/sub) extending from the same interface that declares a field. See updated test case in the webrev.
> 
> I have an idea to retain Field[] arrays and then process ‘em all at the end of the method to produce the final array. That should hopefully make the logic clearer too.
> 
> Paul.
> 
> 
>> On 29 Nov 2017, at 16:00, Claes Redestad <claes.redestad at oracle.com> wrote:
>> 
>> Hi Paul,
>> 
>> it seems you'll effectively skip processing of the last interface of c in the new code - is this intentional?
>> 
>> 3049         Field[] iFields = null;
>> 3050         for (Class<?> c : getInterfaces()) {
>> 3051             if (iFields != null && iFields.length > 0) {
>> ...
>> 3060             }
>> 3061             iFields = c.privateGetPublicFields();
>> 3062         }
>> 
>> ifaces is unused:
>> 
>> 3047         Class<?>[] ifaces = getInterfaces();
>> 
>> Nit: You could probably simplify code by replacing List<Field> fields with the LinkedHashSet directly, removing the need to create it conditionally.
>> 
>> /Claes
>> 
>> 
>> On 2017-11-29 21:15, Paul Sandoz wrote:
>>> Hi,
>>> 
>>> Please review:
>>> 
>>>  http://cr.openjdk.java.net/~psandoz/jdk10/JDK-8186961-iface-static-fields-get/webrev/ <http://cr.openjdk.java.net/~psandoz/jdk10/JDK-8186961-iface-static-fields-get/webrev/>
>>> 
>>> There is a bug lurking, perhaps for a while, where diamond patterns for interface hierarchies can result in the incorrect reporting of fields when using reflection, see the test case.
>>> 
>>> Since reflection data is cached i don’t see an advantage to retaining a set of of traversed interfaces, which is the root cause of the issue.
>>> 
>>> The code is optimized for common cases and will for less common cases collect fields of interfaces into a temporary linked hash set (to preserve the order, perhaps not strictly necessary but i did not want to change that behaviour).
>>> 
>>> Thanks,
>>> Paul.
>> 
>