> The [Linux] kernel already contains some C++

Are you sure? I don't think the kernel even compiles with a C++ compiler [1]. Also, I just ran cloc on my linux repo and didn't get any actual C++ code.

Perhaps some external kernel modules are written in C++, but that seems like a bad idea too [2].

[1] https://www.phoronix.com/scan.php?page=news_item&px=45-Linux... [2] https://www.threatstack.com/blog/c-in-the-linux-kernel