RFR: 8314488: Compiling the JDK with C++17

[Johan Sjölen]

On Wed, 20 Aug 2025 14:44:21 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> I'm hijacking the PR mechanism as a way to discuss new C++17 features that can
>> be more easily structured and captured than bare email. Once discussion
>> settles down I'll turn the results into HotSpot Style Guide changes. I don't
>> intend to integrate any version of this document to the OpenJDK repository.
>
> doc/cpp17-features.md line 1103:
> 
>> 1101: Template template parameters are barely used (if at all) in HotSpot.
>> 1102: 
>> 1103: [n4051](http://wg21.link/n4051)
> 
> I'm moving this to the permitted category, after realizing that I'd
> unknowingly used it in some exploratory work I'm conducting. Artifically
> disallowing this syntactic regularization serves no useful purpose.

I have used this, so happy to see it being approved. This spurred me to have a second look at this document, seems like I've missed some things.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25992#discussion_r2288903833