RFR: 8224087: Compile C code for at least C99 Standard compliance

[David Holmes]

On 21/05/2019 8:49 am, dean.long at oracle.com wrote:
> Isn't that going to break inline asm?

It doesn't appear to. I'll check what the docs say about such things.

Thanks for flagging it.

David
-----

> dl
> 
> On 5/20/19 3:40 PM, Erik Joelsson wrote:
>> That sounds good to me. I missed that distinction before, but pure c99 
>> does sound better.
>>
>> /Erik
>>
>> On 2019-05-20 15:31, David Holmes wrote:
>>> Hi Volker,
>>>
>>> Thanks for the xlc update - I will incorporate that.
>>>
>>> It has been suggested that we actually set c99 rather than gnu99 to 
>>> avoid any GNU extensions creeping in. Does anyone have any concerns 
>>> with doing that?
>>>
>>> Thanks,
>>> David
>>>
>>> On 21/05/2019 12:05 am, Volker Simonis wrote:
>>>> Hi David,
>>>>
>>>> thanks for considering AIX in your change.
>>>>
>>>> With OpenJDK 13 we've moved to XLC 16 which has a new Clang based
>>>> frontend. The "ucs" feature-suboption [1] you're using in your change
>>>> is only supported in the old, xlc compiler but not in the new xlclang
>>>> any more [2]. However, the good news is that the new xlclang now
>>>> supports the same "-std=gn99" option like gcc and clang, so you could
>>>> easily handle the xlc case now together with gcc and clang as shown in
>>>> this webrev:
>>>>
>>>> http://cr.openjdk.java.net/~simonis/webrevs/2019/8224087/
>>>>
>>>> Otherwise, your change looks good!
>>>>
>>>> Please let me know once you've pushed it. I opened "8224214: [AIX]
>>>> Remove support for legacy xlc compiler" [3] for further cleannups
>>>> because we still set some "-qlanglvl" options for C++ which aren't
>>>> supported by the new compiler either.
>>>>
>>>> Best regards,
>>>> Volker
>>>>
>>>> [1] 
>>>> https://www.ibm.com/support/knowledgecenter/SSGH3R_12.1.0/com.ibm.xlcpp121.aix.doc/compiler_ref/opt_langlvl.html 
>>>>
>>>> [2] 
>>>> https://www.ibm.com/support/knowledgecenter/SSGH3R_16.1.0/com.ibm.xlcpp161.aix.doc/compiler_ref/opt_langlvl_aix.html 
>>>>
>>>>
>>>>
>>>> On Mon, May 20, 2019 at 9:40 AM David Holmes 
>>>> <david.holmes at oracle.com> wrote:
>>>>>
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8224087
>>>>> webrev: http://cr.openjdk.java.net/~dholmes/8224087/webrev/
>>>>>
>>>>> The need to remove a for-loop declaration expression to appease gcc 
>>>>> 4.8
>>>>> annoyed me enough to investigate setting C99 as our minimum allow
>>>>> C-language level when compiling. It turned out to be a lot more 
>>>>> complex
>>>>> a situation than I thought due to toolchain quirks. See lots of 
>>>>> details
>>>>> in the bug report.
>>>>>
>>>>> To summarise the changes:
>>>>> - gcc: force to -std=gnu99
>>>>> - clang force to -std=gnu99
>>>>> - Solaris studio - no effective change
>>>>> - Visual Studio - no change
>>>>> - xlc - no effective change (but we use the explicit flag rather than
>>>>> accepting it as default)
>>>>>
>>>>> I've checked how this works with all the toolchains except xlc as I 
>>>>> have
>>>>> no access to that. Some assistance from someone who can verify the
>>>>> correctness on xlc would be appreciated.
>>>>>
>>>>> Thanks,
>>>>> David
>