[jdk8u-dev] RFR: 8280963: Incorrect PrintFlags formatting on Windows [v2]

[Andrew John Hughes]

On Fri, 13 May 2022 17:38:41 GMT, Alex Kasko <akasko at openjdk.org> wrote:

>> A fix to 8u-only Windows-specific problem with -XX:+PrintFlags* output.
>> 
>> Problem description on Stack Overflow by Andrei Pangin: https://stackoverflow.com/a/63309395
>> 
>> The problem was fixed in jdk9 as part of [JDK-8042893](https://bugs.openjdk.java.net/browse/JDK-8042893), but this [jdk9 change](https://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/115188e14c15) doesn't look like a good candidate for the 8u backport according to [8u Best Practices](https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-June/012002.html). Still the problem manifests itself as a customer-visible bug on Windows because people do use -XX:+PrintFlagsFinal to find out the actual flags picked up by JVM and can be confused by unexpected zeros in the output. Proposed patch cherry-picks the minimal change from [JDK-8042893 commit](https://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/115188e14c15#l53.1).
>> 
>> Mailing list review: https://mail.openjdk.java.net/pipermail/jdk8u-dev/2022-February/014532.html
>> 
>> Testing:
>> 
>>  - [x] regression test is included with the proposed patch
>>  - [x] checked that it builds on Windows 64-bit and 32-bit on VS2017 and VS2010
>>  - [x] ran jtreg:hotspot/test/runtime on Windows and Linux
>
> Alex Kasko 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 one additional commit since the last revision:
> 
>   8280963: Incorrect PrintFlags formatting on Windows

I can approve this now once `jdk8u-fix-request` is added to the bug.

To clarify; I just meant the one `PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC` removal in the file being altered, not the rest of that huge patch. In theory, the changes mean that file should now compile without warnings and so the pragma is redundant. But this is something was can do under a separate bug.

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PR: https://git.openjdk.java.net/jdk8u-dev/pull/45