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

[pinskia at gcc dot gnu.org]

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

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Martin Sebor from comment #4)
> 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.

The others are a problem, see PR 24222 for the meta-bug about it.

A simple testcase is to use __builtin_va_start directly with no arguments.