RFR: 8314488: Compile the JDK as C++17 [v6]

[Thomas Stuefe]

On Mon, 5 Feb 2024 09:44:02 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> > Sure, you can always install a newer GCC than the system one, but it's another thing that makes it harder for people to build OpenJDK. Having said that, C++17 is nice to have.
> 
> @theRealAph I am still just hearing hand-waving "perhaps someone somewhere will have a somewhat harder time building the JDK". Yes, perhaps that is so. But that is very uncertain, and I have still not heard a single concrete example of where this would apply. In contrast, going to gcc 10 will clearly bring a benefit to all other platforms, since it allows us to synchronize the code base at C++17.
> 
> In light of this, I think we need to hear some really compelling evidence of problems that would ensue if we raise the minimum to gcc 10. If nobody can produce such evidence, then to me it is a sign that this fear is not well-grounded, and we should proceed with this PR.

@magicus You put the onus of proving that problems could ensue strictly to the objectors. That is a bit one-sided. I do not see much effort - any, really - put into detailing the motivation for this move, neither in the PR description nor in the JBS issue text. I just read through the whole PR discussion and really the only helpful comment I found was from Kim ( https://github.com/openjdk/jdk/pull/14988#issuecomment-1858136247 ).

I think important decisions like enforcing C++17 would benefit from a more careful preparation.

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PR Comment: https://git.openjdk.org/jdk/pull/14988#issuecomment-1946628523