Re: [Emacs-diffs] emacs-26 f274cbd: Avoid reordering of output in 'shr-insert-document'

[martin rudalics <rudalics@gmx.at>]

 > If we do that, then why use save-window-excursion in the first place?
 > That's what it's supposed to preserve (among other things), right?

Not really.  The Elisp manual says about `save-window-excursion' that

      This macro records the window configuration of the selected frame,
      executes FORMS in sequence, then restores the earlier window
      configuration.

and about window configurations

     As a special exception, the window
   configuration does not record the value of point in the selected window
   for the current buffer.

so the point of the selected window is not necessarily restored.

 > If it doesn't do that much, let's do its job by hand altogether.  (And
 > then, of course, a few years down the line someone will come and ask
 > herself why don't they just use save-window-excursion.)

Well, `set-window-buffer' isn't that innocuous either.

Note that `shr-pixel-column' will also fail when the current buffer is
not shown in the selected window.  Hence, a more correct version should
do:

(defun shr-pixel-column ()
   (cond
    ((not shr-use-fonts)
     (current-column))
    ((not (eq (window-buffer) (current-buffer)))
     (let ((window-point (window-point)))
       (prog1
           (save-window-excursion
             ;; Avoid errors if the selected window is a dedicated one,
             ;; and they just want to insert a document into it.
             (set-window-dedicated-p nil nil)
	    (set-window-buffer nil (current-buffer))
	    (car (window-text-pixel-size nil (line-beginning-position) (point))))
         (set-window-point nil window-point))))
    (t
     (car (window-text-pixel-size nil (line-beginning-position) (point))))))

But without a doc-string I obviously can't tell for sure.

martin