bug#2993: 23.0.92; posn-col-row wrong with line-spacing in terminals

[Nikolaj Schumacher <me@nschum.de>]

Eli Zaretskii <eliz@gnu.org> wrote:

>> posn-col-row uses the `line-spacing' value in terminals.  According to the
>> doc `line-spacing' only has an effect in window systems.
>
> You mean, on graphic displays.

Yes.

If that wording is inaccurate, it should also be fixed in the doc
for `line-spacing', which says: "The space is measured in pixels, and
put below lines on window systems."

> Please use `display-graphic-p' rather than assuming that if
> `window-system' is non-nil, the display is necessarily a graphic one.
> At least one Emacs configuration violates this assumption.

I see.

--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -933,8 +933,10 @@ and `event-end' functions."
 	     (x (/ (car pair) (frame-char-width frame)))
 	     (y (/ (cdr pair) (+ (frame-char-height frame)
 				 (or (frame-parameter frame 'line-spacing)
-                                     ;; FIXME: Why the `default'?
-				     (default-value 'line-spacing)
+				     (when (display-graphic-p
+					    (frame-terminal frame))
+				       ;; FIXME: Why the `default'?
+				       (default-value 'line-spacing))
 				     0)))))
 	(cons x y))))))


regards,
Nikolaj Schumacher