bug#57837: 29.0.50; fit-window-to-buffer should reposition the buffer

[Eli Zaretskii]

> From: Sam Steingold <sds@gnu.org>
> Date: Thu, 15 Sep 2022 13:31:48 -0400
> 
> When the buffer is smaller than the window, move the point to the end
> and do `C-x w -` (fit-window-to-buffer).
> The window shrinks, but it is empty - the whole buffer is above.
> One has to move the point to the beginning-of-buffer to make the buffer
> visible.
> 
> I think this is a bug - the window should show the whole buffer; after
> all this is the raison d'etre of `fit-window-to-buffer', right?

Yes, but by having point at EOB (and assuming the last line ends in a
newline), you've made point be outside of the window's text.  Instead
of moving point to the end, move it to last line of the buffer, and
then "C-x w -" will leave the entire buffer text on display.

So I don't think there's a bug here.

> Basically, after `fit-window-to-buffer' is called, the following should
> evaluate to t:
> 
> --8<---------------cut here---------------start------------->8---
> (and (pos-visible-in-window-p (point-min))
>      (pos-visible-in-window-p (point-max)))
> --8<---------------cut here---------------end--------------->8---

No, because point-max is after the last newline, and thus effectively
one line beyond the window's text.