I would love this.
Though I am not likely to filter out C++ stories; I always feel a little sadness when I discover a C-tagged story that is really C++-related.
C++ is not a strict superset of C (it hasn’t been since at least C99); and since, the two languages have diverged dramatically with only a few features from C++ being migrated back to C.
If a C++ tag is not created, I would, at least, argue for the C tag being renamed C-family so that it is more encompassing and so my hopes are not so high when I see it.
I agree and would also not filter it out but I can see myself filtering down to just C stories. I am not interested in C++ but having a way to just list plain C articles would be useful.
I find this similar to having FreeBSD/NetBSD/OpenBSD as separate tags - they are all BSD/Unix but different enough to warrant their own sections. C is also not C++ even if they share a common origin.
I don’t see much point in ‘C family’ tag, as it’s hard to recall a single article or blog post that is relevant to all of the “family” at once and is not a 1000th rant about the perils of unmanaged memory.