bug#34769: Bug in emacs 26.1 gdb-send match-string applied after non-matching string-match

[Eli Zaretskii]

> Date: Wed, 6 Mar 2019 21:10:54 +0100 (CET)
> From: Tobias Zawada <i_inbox@tn-home.de>
> Cc: 34769@debbugs.gnu.org
> 
> Dear Eli,
> thanks for looking into this.
> 
> > > It is wrong to call (match-string 3 string) if (string-match 
> > > gdb-control-commands-regexp string) returned nil.
> > ...
> > That is true, and a cleanup is a good idea. But please note that the
> > undefined results are not used if control-command-p is nil, so the
> > issue is not that serious.
> 
> The match data is that one of the previous successful matching operation.
> One gets an args-out-of-range signal if the indexes in the match data are 
> larger than the width of the string argument to match-string. That is how I 
> discovered the error.

You are right; I've now fixed this on the emacs-26 branch.