RFR: 8314488: Compile the JDK as C++17 [v5]

[Magnus Ihse Bursie]

On Thu, 11 Jan 2024 11:33:07 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Julian Waters has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove unnecessary -std=c++17 option in Lib.gmk
>
> Regarding https://github.com/TheShermanTanker/jdk/actions/runs/7070564987/job/19247370401, could it be that the adlc build didn't get the correct C++ version flags? It doesn't look like a clang 13 specific problem.

@TheRealMDoerr The adlc build is notoriously problematic, since it does not share the common flags set for JVM or JDK native compilation. :( So your suggestion sounds highly likely to me. Running with LOG=cmdlines will confirm this.

(This can be done on GHA by manually starting a run, and setting the value of "Additional make arguments" to `LOG=cmdlines` or possibly `LOG=info,cmdlines`)

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PR Comment: https://git.openjdk.org/jdk/pull/14988#issuecomment-1887040102