From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Stefan Kangas <stefan@marxist.se>
Cc: 39233@debbugs.gnu.org
Subject: bug#39233: .elc file - possibly outdated backward compatibility comments
Date: Thu, 23 Jan 2020 11:26:52 -0500 [thread overview]
Message-ID: <jwva76eqha2.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <87zhefkhi9.fsf@marxist.se> (Stefan Kangas's message of "Wed, 22 Jan 2020 09:44:14 +0100")
> 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.
Stefan
next prev parent reply other threads:[~2020-01-23 16:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-22 8:44 bug#39233: .elc file - possibly outdated backward compatibility comments Stefan Kangas
2020-01-22 17:13 ` Eli Zaretskii
2020-01-23 16:26 ` Stefan Monnier [this message]
2020-01-24 9:20 ` Eli Zaretskii
2020-01-24 14:22 ` Stefan Monnier
2020-01-24 14:36 ` Lars Ingebrigtsen
2020-01-24 16:08 ` Stefan Kangas
2020-01-24 15:23 ` Eli Zaretskii
2020-01-24 17:29 ` Stefan Monnier
2020-01-24 18:45 ` Stefan Monnier
2020-01-24 19:06 ` Stefan Kangas
2020-01-24 19:14 ` Stefan Monnier
2020-01-24 19:19 ` Glenn Morris
2020-01-24 20:08 ` Eli Zaretskii
2020-09-21 12:56 ` Lars Ingebrigtsen
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