[Bug c/107980] va_start does not warn about an arbitrary number of arguments in C2x mode

[jsm28 at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107980

--- Comment #20 from Joseph S. Myers <jsm28 at gcc dot gnu.org> ---
I think it's fine for such QoI diagnostics to happen during compilation.

Note that there is no requirement for [] or {} to be balanced in the additional
arguments, only ().