The converse is that if your class is just a standard layout object with a trivial destructor, you can expose an equivalent C definition without all the C++ sug

The converse is that if your class is just a standard layout object with a trivial destructor, you can expose an equivalent C definition without all the C++ sugar and avoid the forced allocation. The allocation and the opaque handler can still be useful for ABI stability purposes, but that's true in C++ as well.