bug#33114: 25.2; Emacs hangs on closing a perenthesis in a regexp in cperl mode

[Eli Zaretskii <eliz@gnu.org>]

> From: Vincent Lefevre <vincent@vinc17.net>
> Date: Mon, 22 Oct 2018 02:37:49 +0200
> 
> 
> Consider the following file:
> 
> # -*- mode: cperl -*-
> s/./(/e;
> 
> 1. Open it with "emacs -Q".
> 2. Put the cursor just after the opening parenthesis.
> 3. Type ')' (closing parenthesis).
> 
> This makes Emacs hang. A C-g alone has no effect. Several C-g in a row
> may give the control back to the user.

Does the patch below produce good results?  (I don't use CPerl mode,
so I don't know if the highlighting after the change is correct.)

Thanks.

--- lisp/progmodes/cperl-mode.el~0	2018-06-11 06:32:21.000000000 +0300
+++ lisp/progmodes/cperl-mode.el	2018-10-23 18:02:06.924582600 +0300
@@ -8786,7 +8786,7 @@
 	(goto-char new-beg)))
     (setq beg (point))
     (goto-char end)
-    (while (and end
+    (while (and end (< end (point-max))
 		(progn
 		  (or (bolp) (condition-case nil
 				 (forward-line 1)