[PATCH] argp: argp.doc prints incorrectly when it starts with "\v" [BZ #19038]

[DJ Delorie]

Girish Joshi <girish946@gmail.com> writes:
> +        if ((!vt && !child) || (text == inp_text && !first_only))

I stared at this code for a long time, and I'm still not sure I
understand it.  I think that means the code is wrong, even if it does
the right thing.

The original bug has the root cause:

 "When processing what should come before the '\v', this section sets
  inp_text = doc and inp_text_limit = 0. That value of inp_text_limit is
  interpreted later to mean "print the whole string."

Would the logic be easier to follow if you just initialized
inp_text_limit to -1 and have -1 mean "print the whole string"?  That
way a value of zero is unambiguously an empty string.

You'd end up with code like this:

>   size_t inp_text_limit = -1;

>   inp_text_limit = (!post && vt) ? (vt - doc) : -1;

>   if (text == inp_text && inp_text_limit != -1)