> The fourth is, that the `default` case needs a template, which we
> obviously don't have in C and which we will probably never have, for
> the same reasons.
>
Envisioning generic as a group of overloads is interesting. With C++, we
now have abbreviated function templates, so even the non-default cases can
be templates somewhat directly. The observation that C++ could use
something like generic was the subject of a previous paper:
https://wg21.link/p0404.