Void is surprisingly useful.

> Anyway, if you're going to give examples in GNU C, you should specify. ISO is the standard dialect (GCC's out-of-the-box behavior notwithstanding).

I say it now. ISO C is like speaking standard Latin: nobody does it, and nobody ever did (except maybe a few Romans, during a few years, and maybe neither). It's good as a guideline on which to base dialects, not as an actual dialect meant to be directly useful. Very few programs (none that are non-trivial?) are strictly conforming to ISO C (and even less to ISO C90).

> But my point is that in the general case, where you may want to write arbitrary code, you do face a combinatorial explosion. There might happen to be a few special cases where it's not strictly necessary...

I write a lot of type-generic code using GNU C23, and only have a few places where I've had to duplicate code; they are the special case, IME. We're working to improve the language in ways that those special cases may not be needed in the future.

> but Rust in particular is not a fan of this sort of thing.

I don't write any Rust, but this seems consistent with what I've heard, and with the little Rust I've read: it tends to be more verbose than C.