[foreign] RFR 8217784: Ignore anonymous bitfields so they are handled as padding

[Maurizio Cimadamore]

On 28/01/2019 09:41, Sundararajan Athijegannathan wrote:
> Looks good. Mac build/test fine.
>
> Minor: why is the specific imports in bitfields.java are replaced with 
> import *. Your IDE?

That happens with me too with IntelliJ - you need to tweak import 
setting and tell the IDE to use star import when you have a ridiculously 
high number of inner classes (e.g. 9999). :-)

Maurizio

>
> -Sundar
>
> On 26/01/19, 2:56 AM, Maurizio Cimadamore wrote:
>> Looks good by me - I suggest you also wait for Sundar's opinion, 
>> since he's fresh with this code
>>
>> Maurizio
>>
>> On 25/01/2019 21:24, Maurizio Cimadamore wrote:
>>> The patch is functionally good, I just wonder if it's too magic - 
>>> e.g. wouldn't be better if the record computer processed the 
>>> anonymous bitfield (so that the correct padding can be added) 
>>> instead of relying on the right thing to happen (which will be 
>>> fragile if e.g. the impl changes a bit) ?
>>>
>>> Maurizio
>>>
>>> On 25/01/2019 19:18, Jorn Vernee wrote:
>>>> Good catch. I kinda glossed over unions since I thought there would 
>>>> be no point in having anonymous bitfields in a union, since there 
>>>> is no need for padding - but on second thought, these could be used 
>>>> to manually widen the type. Any ways, the compiler seems to allow 
>>>> anonymous bitfields in unions, so it's good to support that as well.
>>>>
>>>> Updated webrev: 
>>>> http://cr.openjdk.java.net/~jvernee/panama/webrevs/8217784/webrev.01/
>>>>
>>>> Jorn
>>>>
>>>> Maurizio Cimadamore schreef op 2019-01-25 19:25:
>>>>> Looks good - but what happens with unions? I'm worried we'd get a
>>>>> similar failure there...
>>>>>
>>>>> Maurizio
>>>>>
>>>>> On 25/01/2019 13:52, Jorn Vernee wrote:
>>>>>> Hi,
>>>>>>
>>>>>> From the bug description:
>>>>>>
>>>>>> Jextract fails on the following example:
>>>>>>
>>>>>> ```
>>>>>> struct Foo {
>>>>>>     unsigned int x: 1;
>>>>>>     int :7;
>>>>>>     unsigned int y: 8;
>>>>>>     int :16;
>>>>>>     int z;
>>>>>> };
>>>>>> ```
>>>>>>
>>>>>> The current code tries to look up the second field, but because 
>>>>>> it has no name this throws an illegal field name error.
>>>>>>
>>>>>> ---
>>>>>>
>>>>>> I've fixed this by ignoring anonymous bitfields, since the 
>>>>>> StructLayoutComputer inserts padding automatically before the 
>>>>>> next field.
>>>>>>
>>>>>> Please review the following.
>>>>>>
>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8217784
>>>>>> Webrev: 
>>>>>> http://cr.openjdk.java.net/~jvernee/panama/webrevs/8217784/webrev.00/ 
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Jorn