meson/docs/markdown/snippets/rust-bindgen-cpp.md

Bindgen will now use Meson's heuristic for what is a C++ header

Bindgen natively assumes that a file with the extension .hpp is a C++ header, but that everything else is a C header. Meson has a whole list of extensions it considers to be C++, and now will automatically look for those extensions and set bindgen to treat those as C++