From: "João Távora" <joaotavora@gmail.com>
To: "Basil L. Contovounesios" <contovob@tcd.ie>
Cc: darthandrus@gmail.com, 40693-done@debbugs.gnu.org,
Dmitry Gutov <dgutov@yandex.ru>
Subject: bug#40693: 28.0.50; json-encode-alist changes alist
Date: Fri, 22 May 2020 21:14:20 +0100 [thread overview]
Message-ID: <87eerbybfn.fsf@gmail.com> (raw)
In-Reply-To: <87sgfs81g6.fsf@tcd.ie> (Basil L. Contovounesios's message of "Fri, 22 May 2020 15:54:33 +0100")
"Basil L. Contovounesios" <contovob@tcd.ie> writes:
>> Am I missing something or doesn't this work like you want?
>
> There's a problem with the conditional require at byte-compile time. If
> the version of Emacs doing the byte-compilation has native JSON support,
> then it will generate invalid byte-code (and complain) for the case
> where there is no native JSON support. In other words, there will be a
> bug when an Emacs without native JSON loads a file that was
> byte-compiled in an Emacs with native JSON.
This doesn't give any any warning:
(defvar foo-42 42)
(provide 'foo)
;; foo.el ends here
and a bar.el
(eval-and-compile
(defvar bar-have-native-42 t) ;; or nil
(unless bar-have-native-42
(require 'foo)))
(defalias 'forty-two
(if (eval-when-compile bar-have-native-42)
(lambda () (message "%s" 42.0))
(lambda () (message "%s" foo-42))))
;; bar.el ends here
And it seems to work in both cases:
~/tmp ❯❯❯ emacs -Q --batch -L . -f batch-byte-compile bar.el
~/tmp ❯❯❯ emacs -Q --batch -L . -l bar.elc -f forty-two
42.0
# now change that t to nil
~/tmp ❯❯❯ emacs -Q --batch -L . -f batch-byte-compile bar.el
~/tmp ❯❯❯ emacs -Q --batch -L . -l bar.elc -f forty-two
42
But indeed in the recipe I gave you, I had forgotten the second
eval-when-compile. If you take that away, it warns again.
No idea how to check if byte-code is "valid" or not: I just check the
warnings. Can you tell me?
> Thanks. I've therefore gone with the original patch[1], as it exhibits
> correct behaviour and is the least intrusive, but you should obviously
> feel free to tweak it as you prefer.
I think I'll let it be, the reason I'm not a huge fan is the foward
declarations of individual functions and variables, but it's not so bad.
João
next prev parent reply other threads:[~2020-05-22 20:14 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-18 2:59 bug#40693: 28.0.50; json-encode-alist changes alist Ivan Andrus
2020-04-18 17:29 ` Dmitry Gutov
2020-04-18 21:00 ` Ivan Andrus
2020-04-18 23:13 ` Michael Heerdegen
2020-04-19 0:10 ` Dmitry Gutov
2020-04-19 0:29 ` Michael Heerdegen
2020-04-19 0:33 ` Basil L. Contovounesios
2020-04-19 0:34 ` Basil L. Contovounesios
2020-04-29 10:11 ` Basil L. Contovounesios
2020-04-29 10:30 ` Eli Zaretskii
2020-04-29 12:08 ` Dmitry Gutov
2020-04-29 12:21 ` Eli Zaretskii
2020-04-29 14:28 ` Dmitry Gutov
2020-04-29 14:40 ` Eli Zaretskii
2020-04-29 15:02 ` Dmitry Gutov
2020-04-29 15:07 ` Eli Zaretskii
2020-04-29 14:41 ` Basil L. Contovounesios
2020-05-18 1:24 ` Basil L. Contovounesios
2020-05-18 14:27 ` Eli Zaretskii
2020-05-18 22:50 ` Dmitry Gutov
2020-05-18 23:50 ` João Távora
2020-05-21 21:14 ` Basil L. Contovounesios
2020-05-21 22:16 ` João Távora
2020-05-22 14:54 ` Basil L. Contovounesios
2020-05-22 20:14 ` João Távora [this message]
2020-05-23 16:13 ` Basil L. Contovounesios
2020-05-23 19:40 ` João Távora
2020-05-23 22:41 ` Basil L. Contovounesios
2020-05-23 22:45 ` João Távora
2020-04-19 20:35 ` Paul Eggert
2020-04-19 21:01 ` Drew Adams
2020-04-19 22:14 ` Paul Eggert
2020-04-19 22:29 ` Michael Heerdegen
2020-04-19 23:59 ` Paul Eggert
2020-04-20 0:25 ` Michael Heerdegen
2020-04-20 0:32 ` Paul Eggert
2020-04-20 0:57 ` Michael Heerdegen
2020-04-20 2:55 ` Paul Eggert
2020-04-20 14:56 ` Eli Zaretskii
2020-04-20 5:45 ` Drew Adams
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