Fix integer overflow in forward-point

* lisp/subr.el (forward-point): Rewrite in Lisp and move here ...
* src/cmds.c (Fforward_point): ... from here.  This fixes an
integer overflow bug with (forward-point most-positive-fixnum).

2 files changed, 5 insertions, 11 deletions

diff --git a/lisp/subr.el b/lisp/subr.el
index 123557e736b..70f33ee5bdb 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1558,7 +1558,6 @@ be a list of the form returned by `event-start' and `event-end'."
 
 ;;;; Obsolescent names for functions.
 
-(make-obsolete 'forward-point "use (+ (point) N) instead." "23.1")
 (make-obsolete 'buffer-has-markers-at nil "24.3")
 
 (make-obsolete 'invocation-directory "use the variable of the same name."
@@ -1580,6 +1579,11 @@ be a list of the form returned by `event-start' and `event-end'."
 (make-obsolete 'string-as-multibyte "use `decode-coding-string'." "26.1")
 (make-obsolete 'string-make-multibyte "use `decode-coding-string'." "26.1")
 
+(defun forward-point (n)
+  "Return buffer position N characters after (before if N negative) point."
+  (declare (obsolete "use (+ (point) N) instead." "23.1"))
+  (+ (point) n))
+
 (defun log10 (x)
   "Return (log X 10), the log base 10 of X."
   (declare (obsolete log "24.4"))
diff --git a/src/cmds.c b/src/cmds.c
index 5d7a45e65f6..5b98a09fda9 100644
--- a/src/cmds.c
+++ b/src/cmds.c
@@ -31,15 +31,6 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 static int internal_self_insert (int, EMACS_INT);
 
-DEFUN ("forward-point", Fforward_point, Sforward_point, 1, 1, 0,
-       doc: /* Return buffer position N characters after (before if N negative) point.  */)
-  (Lisp_Object n)
-{
-  CHECK_FIXNUM (n);
-
-  return make_fixnum (PT + XFIXNUM (n));
-}
-
 /* Add N to point; or subtract N if FORWARD is false.  N defaults to 1.
    Validate the new location.  Return nil.  */
 static Lisp_Object
@@ -526,7 +517,6 @@ syms_of_cmds (void)
 This is run after inserting the character.  */);
   Vpost_self_insert_hook = Qnil;
 
-  defsubr (&Sforward_point);
   defsubr (&Sforward_char);
   defsubr (&Sbackward_char);
   defsubr (&Sforward_line);