[Bug c/26749] too few arguments to function va_start is caught too late

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26749

--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
Yes, I see the error there.  There are 53 calls to error() or error_at() in the
file.  I'm trying to understand why you think this particular one is a problem
(and the others aren't) and how that problem could be triggered.  I.e., a test
case.