bug#22025: Emacs 25 corrupts Emacs 24 .emacs.desktop.

[Alan Mackenzie <acm@muc.de>]

Hello, Eli.

On Fri, Nov 27, 2015 at 11:05:25AM +0200, Eli Zaretskii wrote:
> > Date: Fri, 27 Nov 2015 08:38:37 +0000
> > From: Alan Mackenzie <acm@muc.de>

> > Emacs 25 has read a version 206 .desktop file, but written a version 208
> > file on termination.  Emacs 24 cannot execute this version.

> > There was no yes-or-no-p asking "are you sure you want to convert your
> > desktop to a format incompatible with previous Emacs versions?".

> > Manually restoring a .desktop to version 206 is fraught with
> > difficulties, even for somebody (myself) who understands the issues
> > reasonably well, and has an old version of .desktop saved "just in
> > case".

> > Recommendation
> > --------------

> > Emacs 25, having loaded a version 206 .desktop, should save it in the
> > same format until the user has positively consented to it being
> > converted to version 208.

> This would be a nice enhancement, but it certainly isn't a bug in my
> book.

I couldn't disagree more.  Users should be free to update to Emacs 25,
but it shouldn't be for us to force them.

I've just lost half a morning restoring my .desktop to the earlier
format.  Most users wouldn't be able to do this.

I think we are enormously cavalier with the .desktop file - no backup of
any type (such as .emacs.desktop~) is kept, and should there be trouble
reading .desktop, it is difficult to exit Emacs without having this
.desktop overwritten.

> Of course, if making that happen is relatively easy, it would be good
> to have such a compatibility mode.  Patches welcome.

I will work on this.

> I marked it wishlist.

I really wish you hadn't.

-- 
Alan Mackenzie (Nuremberg, Germany).