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

[Kim Barrett]

On Thu, 26 Jun 2025 02:01:55 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.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25992#discussion_r2288416731