bug#14636: 24.3.50.1; window-line-height doesn't seem to work, unless the point is at the end-of-buffer

[Eli Zaretskii]

> Date: Sun, 16 Jun 2013 18:19:06 +0100
> From: E Sabof <esabof@gmail.com>
> Cc: 14636@debbugs.gnu.org
> 
> You might be confusing posn-at-point (which returns the height of the
> character amoung other things), with pos-visible-in-window-p, which returns
> t or nil.

I'm not confusing them.  And pos-visible-in-window-p can return more
than just nil or t, see its doc string.

> In any case, the height of the character can be different from the height
> of the line, so they are not equivalent.

They are not equivalent, in the sense that a single call to
pos-visible-in-window-p will not do what window-line-height does.  You
need to call pos-visible-in-window-p twice, for the line you are
interested in and the one after it, to get the same information.

> So either a) the documentation is incomplete and misleading, or b)
> there is a bug in the implementation (which I think is more likely,
> given the arbitrary circumstances under which this function does and
> doesn't work).

There's no bug.  It looks arbitrary to you because whether the window
display is up-to-date when window-line-height runs is impossible to
predict.  Take a look at the source of window-line-height, and you
will see it.