Re: Bug: Exporting "as PDF file and open" causes unnecessary revert prompt if PDF was already open [9.4 (release_9.4-103-gf0b8de @ /home/erik/.emacs.d/straight/build/org/)]

[Tim Cross]

Erik Hahn <mail@erikhahn.eu> writes:

> In a graphical emacs -Q instance, open any Org file. Export it as PDF and open
> (C-e l o). Then do the same again. Emacs prompts "File foo.pdf changed
> on disk. Reread from disk (yes or no)" although no external program (not
> counting latex as external here as it was started by Emacs) actually
> changed the file.
>
> Emacs  : GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.14)
>  of 2020-03-26, modified by Debian
> Package: Org mode version 9.4 (release_9.4-103-gf0b8de @ 
> /home/erik/.emacs.d/straight/build/org/)

Hmm. Not sure if this is strictly speaking a bug. Latex is an external
program and the process does replace the file on disk, so it has changed
compared to the buffer. So at that level, the revert seems normal.

However, Emacs knows this process has occurred and knows it should
re-read from disk as a new PDF has just been created, so perhaps it
should just do the revert without asking? This may have consequences for
users who are working with large PDF documents and high DPI settings who
may not want to re-generate the PDF every time, so it may be necessary
to make the auto reloading an option?

--
Tim Cross