Re: Preview: portable dumper

[Joost Kremers]

On Sat, Dec 03 2016, Eli Zaretskii wrote:
> > Date: Fri, 2 Dec 2016 16:07:24 -0800 (PST)
> > From: Drew Adams <address@hidden>
> > Cc: address@hidden, address@hidden
> >
> > > Only rarely have we made changes that would prevent this.
> >
> > That used to be the case.  Now, nearly every major release is
> > incompatible, AFAICT.  As far as I can see, long gone are the
> > days when you could byte-compile in an older version and use
> > the byte-compiled code in a newer version.
>
> I'm not aware of such problems.  AFAIK, we only made an 
> incompatible
> change once, in Emacs 23.  The byte-compiled files compiled by 
> later
> versions should all be compatible.  If you see a problem with 
> that,
> please report it as a bug.

Well, I may have run into a problem of this kind: a package 
(`expand-region') that started behaving weird when I moved from 
Emacs 24.5 to a 25 pretest. I did not recompile any packages when 
I upgraded Emacs, so when I ran into the problem, I was running 
Emacs 24 byte code in Emacs 25. When I recompiled `expand-region', 
the problem I was experiencing went away.

I didn't investigate further (I know zilch about Emacs' byte code 
and my problem was solved), so I can't be 100% sure it was due to 
a byte code incompatibility, it just seemed likely. (I also didn't 
consider filing a bug with Emacs, because it made sense to me 
*not* to expect byte-code compatibility across major versions.)

Anyway, the details are here (no technical details, just a 
description of the problem):

https://github.com/magnars/expand-region.el/issues/195


--
Joost Kremers
Life has its moments