Huh, I wouldn't think of function pointers as a hidden edge in the language, and I've only been seriously using C for about 4 years.

Is there some crazy consequence of using function pointers that I've been missing? Callbacks are pretty ubiquitous in C code bases, and the "hand coded vtable" pattern isn't too uncommon.

Maybe the lesson is that what language feature are the "hidden edges" depend on one's domain.