RFR: 8314488: Compiling the JDK with C++17 [v3]

[Magnus Ihse Bursie]

On Mon, 25 Aug 2025 09:42:45 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Please review this change to use C++17 for building C++ parts of the JDK. In
>> particular this affects HotSpot. This change also includes an update to the
>> HotSpot Style Guide regarding C++17 features and their use in HotSpot code.
>> 
>> Testing: mach5 tier1-8
>> 
>> This change includes a modification of the Style Guide. Rough consensus among
>> the HotSpot Group members is required to make such a change. Only Group
>> members should vote for approval (via the github PR), though reasoned
>> objections or comments from anyone will be considered. A decision on this
>> proposal will not be made before Friday 5-September-2025 at 12h00 UTC.
>> 
>> Since we're piggybacking on github PRs here, please use the PR review process
>> to approve (click on Review Changes > Approve), rather than sending a "vote:
>> yes" email reply that would be normal for a CFV.
>
> Kim Barrett has updated the pull request incrementally with one additional commit since the last revision:
> 
>   dholmes tweaks

The build change looks fine. I'd like to point out that this change will apply to all C++ code in the JDK, not only Hotspot. I don't think it is a problem; most other native libraries are almost trivial compared to Hotspot, and not many cares about intricacies like C++ version.

This is not a vote on the hotspot guide change.

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Marked as reviewed by ihse (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26884#pullrequestreview-3151936814