Doesn't this mostly boil down to "C99 and C++ aren't compatible anymore"? One of the big gotchas of C++ is that lots of people think it's a superset of C, but

Doesn't this mostly boil down to "C99 and C++ aren't compatible anymore"? One of the big gotchas of C++ is that lots of people think it's a superset of C, but that's only (mostly) correct for ANSI C (C89). In my experience not even C99 is completely compatible with C89. One of the initial pain points when clang was young was that GCC used C89 as default, so lots of old stuff didn't build out of the box due to changes to how `inline` behaves or undefined symbols not being allowed anymore.