[clang] Diagnose the code with trailing comma in the function call. (PR #125232)

[Björn Pettersson via cfe-commits]

bjope wrote:

Thanks. I see now that it did not work with older clang (at least not 19.1.0).

It did however work with our downstream fork before this patch. I haven't figured out how we avoided the error in the past. I guess we must have something downstream that avoided the error in the past, but I can't remember that we've done anything actively to suppress such errors. Weird.

I also agree that our downstream users should try to use __VA_OPT__ instead (hopefully there are no other tools that would complain about that).

https://github.com/llvm/llvm-project/pull/125232