Box2D has moved from C++ to C for this v3.0 release. Erin has explained why further down in the post:
https://box2d.org/posts/2024/08/releasing-box2d-3.0/#moving-...
https://box2d.org/posts/2024/08/releasing-box2d-3.0/#moving-...
The reasons given here felt more insightful to me: https://box2d.org/documentation/md_faq.html
> Box2D is designed to be portable and easy to wrap with other languages, so I decided to use C11. I used C11 to get support for atomics.