bug#32189: 27.0.50; GCC 7 warning due to -Wformat-truncation=2

[Ken Brown]

On 7/20/2018 2:56 AM, Eli Zaretskii wrote:
> > From: Paul Eggert <eggert@cs.ucla.edu>
> > Date: Thu, 19 Jul 2018 16:19:38 -0700
> > Second, the code in question uses snprintf followed by build_string, and can be
> > simplified by using vformat_string instead. That would avoid the warnings and
> > should make the code more reliable. Something like the attached patch, say. I
> > haven't tested it since I don't use MS-Windows. Let's use something like this
> > rather than shutting off the warnings.
>
> Works for me (although vformat_string does exactly what a call to
> snprintf does, just with a larger buffer).  Ken, could you please
> check if this works in the Cygwin build?

Yes, although I'm getting the following warning after this change:

../../master/src/w32cygwinx.c: In function ‘format_string’:
../../master/src/w32cygwinx.c:32:3: warning: function ‘format_string’ 
might be a candidate for ‘gnu_printf’ format attribute 
[-Wsuggest-attribute=format]
   Lisp_Object str = vformat_string (format, args);
   ^~~~~~~~~~~

Ken