RFR: 8321688: Build on linux with GCC 7.5.0 fails after 8319577 [v2]

[Guoxiong Li]

On Sun, 17 Dec 2023 13:25:00 GMT, Guoxiong Li <gli at openjdk.org> wrote:

>> Hi all,
>> 
>> This patch fixes the building failure introduced by [JDK-8319577](https://bugs.openjdk.org/browse/JDK-8319577) in old GCC version (linux & GCC 7.5.0 locally).
>> 
>> Thanks for the review.
>> 
>>  Best Regards,
>> -- Guoxiong
>
> Guoxiong Li has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - Bump the needed version of GCC.
>  - Revert previous change.
>  - Merge branch 'master' into JDK-8321688
>  - JDK-8321688

> Have you tested with gcc 9? Or is this just supposition based on gcc9 having removed the experimental
status for C++17?

I have not tested GCC 8 and 9. @sviswa7 seems to test them.

> I have verified that with the above change the builds (release, fastdebug, slowdebug) all succeed with GCC 8.4.0 as well as prior GCC like GCC7.5.0 and the test/jdk/java/util/Arrays/Sorting.java passes successfully with these builds.

Thanks for your tests. But from the description of the [GCC document](https://gcc.gnu.org/projects/cxx-status.html), shown below, it may be good to skip GCC 8 and use GCC 9 directly if we want to switch to C++17.

>  Some C++17 features are available since GCC 5, but support was experimental and the ABI of C++17 features was not stable until GCC 9.

What do you think about it?

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PR Comment: https://git.openjdk.org/jdk/pull/17047#issuecomment-1861998852