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

[Sundararajan Athijegannathan]

Looks good. Mac build/test fine.

Minor: why is the specific imports in bitfields.java are replaced with 
import *. Your IDE?

-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