RFR: 8232084: HotSpot build failed with GCC 9.2.1

[David Holmes]

On 17/10/2019 12:45 pm, Yasumasa Suenaga wrote:
> On 2019/10/17 11:39, David Holmes wrote:
>> On 17/10/2019 12:19 pm, Yasumasa Suenaga wrote:
>>> On 2019/10/17 9:34, David Holmes wrote:
>>>> On 17/10/2019 10:07 am, serguei.spitsyn at oracle.com wrote:
>>>>> Hi Yasumasa,
>>>>>
>>>>> It looks good.
>>>>> One tip:
>>>>>
>>>>> + // This code would be warned as "stringop-truncation" by GCC 8 or 
>>>>> later.
>>>>> +PRAGMA_DIAG_PUSH
>>>>> +PRAGMA_STRINGOP_TRUNCATION_IGNORED
>>>>>         strncpy(buf, str, len);
>>>>> +PRAGMA_DIAG_POP
>>>>>
>>>>>
>>>>> I'd suggest to place the comment before the line with strncopy().
>>>>
>>>> I'd suggest just dropping the comment as it adds nothing, further 
>>>> gcc 8 is not flagging this use of strncpy.
>>>
>>> The comment is suggested in [1].
>>> Indeed stringop-truncation warning was not reported by GCC 8, but 
>>> this option introduced in it,
>>> and I agree with Ioi to add the comment for other developers why this 
>>> #pragma is needed.
>>
>> PRAGMA_STRINGOP_TRUNCATION_IGNORED
>>
>> seems to pretty clearly state what the issue is to me. But if you want 
>> to add a comment to make that more clear fine. But don't mention gcc 8 
>> as it is not relevant to the need for the pragma now.
> 
> I'd like to change the comment as below:
> 
>      This code would be warned as "stringop-truncation" by modern GCC
> 
> Is it ok?

Grammatically it needs work. I propose

// This code can cause a "stringop-truncation" warning with gcc

"modern" will become inaccurate as time goes by.

Thanks,
David

> 
> Yasumasa
> 
> 
>> Thanks,
>> David
>>
>>>
>>> Yasumasa
>>>
>>>
>>> [1] 
>>> https://mail.openjdk.java.net/pipermail/serviceability-dev/2019-October/029578.html 
>>>
>>>
>>>> Otherwise okay.
>>>>
>>>> Thanks,
>>>> David
>>>>
>>>>> Not  subject for re-review.
>>>>>
>>>>> Thanks,
>>>>> Serguei
>>>>>
>>>>>
>>>>> On 10/16/19 16:25, Yasumasa Suenaga wrote:
>>>>>> (Re-send email because I could not send original email to 
>>>>>> serviceability-dev and hotspot-compiler-dev)
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> We discussed the fix for JDK-8232084 in [1], and I think we should 
>>>>>> fix it with #pragma.
>>>>>> I uploaded new webrev. Could you review it?
>>>>>>
>>>>>>   JBS: https://bugs.openjdk.java.net/browse/JDK-8232084
>>>>>>   webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8232084/webrev.03/
>>>>>>
>>>>>> This change has passed the tests on submit repo 
>>>>>> (mach5-one-ysuenaga-JDK-8232084-1-20191016-1534-5969882).
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Yasumasa
>>>>>>
>>>>>>
>>>>>> [1] 
>>>>>> https://mail.openjdk.java.net/pipermail/serviceability-dev/2019-October/029547.html 
>>>>>>
>>>>>