Integrated: 8369186: HotSpot Style Guide should permit some uses of the C++ Standard Library

[Kim Barrett]

On Thu, 2 Oct 2025 07:11:51 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change to the HotSpot Style Guide to suggest that C++
> Standard Library components may be used, after appropriate vetting and
> discussion, rather than just a blanket "no, don't use it" with a few very
> narrow exceptions. It provides some guidance on that vetting process and
> the criteria to use, along with usage patterns.
> 
> In particular, it proposes that Standard Library headers should not be
> included directly, but instead through HotSpot-provided wrapper headers. This
> gives us a place to document usage, provide workarounds for platform issues in
> a single place, and so on.
> 
> Such wrapper headers are provided by this PR for `<cstddef>`, `<limits>`, and
> `<type_traits>`, along with updates to use them. I have a separate change for
> `<new>` that I plan to propose later, under JDK-8369187. There will be
> additional followups for other C compatibility headers besides `<cstddef>`.
> 
> This PR also cleans up some nomenclature issues around forbid vs exclude and
> the like.
> 
> Testing: mach5 tier1-5, GHA sanity tests

This pull request has now been integrated.

Changeset: e8a1a870
Author:    Kim Barrett <kbarrett at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/e8a1a8707ee6192c85ac62a2a51c815e07613c38
Stats:     670 lines in 68 files changed: 430 ins; 134 del; 106 mod

8369186: HotSpot Style Guide should permit some uses of the C++ Standard Library

Reviewed-by: jrose, lkorinth, iwalulya, kvn, stefank

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PR: https://git.openjdk.org/jdk/pull/27601