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bug#39233: .elc file - possibly outdated backward compatibility comments
From: |
Eli Zaretskii |
Subject: |
bug#39233: .elc file - possibly outdated backward compatibility comments |
Date: |
Fri, 24 Jan 2020 11:20:19 +0200 |
> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Thu, 23 Jan 2020 11:26:52 -0500
> Cc: 39233@debbugs.gnu.org
>
> > In the .elc files on my machine, I see the following:
> > ;;; This file uses dynamic docstrings, first added in Emacs 19.29.
>
> It's factually correct, but indeed it not really relevant, we can drop
> this to save some bytes.
>
> > ;;; This file does not contain utf-8 non-ASCII characters,
> > ;;; and so can be loaded in Emacs versions earlier than 23.
>
> Here, this is indeed likely not factually correct: some .elc files might
> indeed work in earlier versions, but that will depend on many other
> things:
> - byte codes have been added in Emacs-24 for the lexical-binding
> support, others were added in Emacs-25, yet more in Emacs-26)
> - macros which expand to code which relies on functions/features only
> provided in newer versions).
> - changes in the reader (e.g. the readable syntax for hash-tables, or
> that of records).
>
> I think more useful would be to emit a warning any time a .elc file is
> loaded into an Emacs that's older than the one with which it
> was compiled since that's a case we "don't support" (at least when the
> major-version is different).
>
> > 1. Is it still correct that the byte compiled file can be loaded on
> > Emacs 22?
>
> It's quite likely that *some* do. But I expect that the vast
> majority don't.
>
> > 3. Following up on point 2, I also see:
> >
> > "\n;;; This file uses "
> > (if dynamic-docstrings
> > "dynamic docstrings, first added in Emacs 19.29"
> > "opcodes that do not exist in Emacs 18")
> >
> > I'm not sure what to do here, but it doesn't seem to make sense to
> > mention Emacs 18 in any case. Of course, this file might use
> > opcodes that do not exist in Emacs 23, or perhaps an even later
> > version.
>
> Throw it all away.
Will these changes still allow old Emacs binaries to load *.elc files
compiled by Emacs after these changes? I hope we won't break that use
case.
- bug#39233: .elc file - possibly outdated backward compatibility comments, Stefan Kangas, 2020/01/22
- bug#39233: .elc file - possibly outdated backward compatibility comments, Eli Zaretskii, 2020/01/22
- bug#39233: .elc file - possibly outdated backward compatibility comments, Stefan Monnier, 2020/01/23
- bug#39233: .elc file - possibly outdated backward compatibility comments,
Eli Zaretskii <=
- bug#39233: .elc file - possibly outdated backward compatibility comments, Eli Zaretskii, 2020/01/24
- bug#39233: .elc file - possibly outdated backward compatibility comments, Stefan Monnier, 2020/01/24
- bug#39233: .elc file - possibly outdated backward compatibility comments, Stefan Monnier, 2020/01/24
- bug#39233: .elc file - possibly outdated backward compatibility comments, Stefan Kangas, 2020/01/24
- bug#39233: .elc file - possibly outdated backward compatibility comments, Stefan Monnier, 2020/01/24
- bug#39233: .elc file - possibly outdated backward compatibility comments, Glenn Morris, 2020/01/24
- bug#39233: .elc file - possibly outdated backward compatibility comments, Eli Zaretskii, 2020/01/24