RFR: build pragma error with gcc 4.4.7

David Holmes david.holmes at oracle.com
Tue Apr 24 04:11:57 UTC 2018



On 24/04/2018 1:27 PM, Andrew Hughes wrote:
> On 23 April 2018 at 20:19, Kim Barrett <kim.barrett at oracle.com> wrote:
>>> On Apr 21, 2018, at 11:18 AM, Andrew Hughes <gnu.andrew at redhat.com> wrote:
>>>
>>> On 19 March 2018 at 23:23, Kim Barrett <kim.barrett at oracle.com> wrote:
>>>> There are also problems with the patch as provided.
>>>>
>>>> (1) Since PRAGMA_DIAG_PUSH/POP do nothing in the version of gcc this
>>>> change is being made in support of, the warning would be disabled for
>>>> all following code in any translation unit that includes this file.
>>>> That doesn't seem good.
>>>
>>> No, but it's really the only solution on those compilers. We have such
>>> usage already elsewhere e.g.
>>>
>>> // Silence -Wformat-security warning for fatal()
>>> PRAGMA_DIAG_PUSH
>>> PRAGMA_FORMAT_NONLITERAL_IGNORED
>>>   fatal(buf);
>>> PRAGMA_DIAG_POP
>>>   return true; // silence compiler warnings
>>> }
>>> in src/hotspot/os_cpu/linux_zero/os_linux_zero.cpp
>>>
>>> If there are other warnings, then they will picked up on newer compilers,
>>> especially when building with -Werror. I don't think it's likely people are
>>> doing development on older compilers, but rather that we have to use
>>> them to build for older platforms.
>>
>> I would be a lot more comfortable if the possibly do-nothing push/pop and
>> the associated code were in a .cpp file, rather than in a .hpp file where it
>> could affect some open-ended and unexpected set of code.
>>
> 
> Ah yes, sorry, I missed that this was a .hpp, while the others were .cpp.
> 
>> But I think this is moot if os::readdir can be changed to call ::readdir rather
>> than ::readdir_r, as appears to be the case, possibly with some documentation
>> about not sharing the DIR* among multiple threads, at least not without locking.
>>
> 
> I think so too for OpenJDK 11, but I'm reluctant to backport such a change
> to older JDKs.
> I guess if we want to continue to workaround the warning there, we'll need
> to move the function into the .cpp file.
> 
>> That seemed to be what Michal was planning to do, but hasn’t gotten back to
>> it yet.
> 
> Indeed. He has a patch that does that, that I've already reviewed. Just waiting
> for him to post it publicly :)

He already has:

RFR: 8179887 - Build failure with glibc >= 2.24: error: 'int 
readdir_r(DIR*, dirent*, dirent**)' is deprecated

on both the mailing lists this email has gone to.

David
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