From: Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: Teika Kazura <teika@gmx.com>
Cc: 62317@debbugs.gnu.org
Subject: bug#62317: 28.2; This byte-compiled file behaves wrongly.
Date: Sat, 01 Apr 2023 12:27:35 -0400 [thread overview]
Message-ID: <jwv355jwple.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <20230321.125408.609857763486645873.teika@gmx.com> (Teika Kazura's message of "Tue, 21 Mar 2023 12:54:08 +0900 (JST)")
> * How to reproduce:
> First, ~/.emacs.d/init.el:
> ------------------------------------------------------------------------
> (eval-and-compile
> (push user-emacs-directory load-path)
> (require 'a))
>
> ;; Hereafter is ignored when byte-compiled.
>
> (defvar foo-var 'baz)
> (message "Hello, world.")
> (pop-to-buffer "*Messages*")
> ------------------------------------------------------------------------
>
> ~/.emacs.d/a.el:
> ------------------------------------------------------------------------
> (set-buffer "*Messages*") ;; or (set-buffer (get-buffer-create "bar"))
> (provide 'a)
> ------------------------------------------------------------------------
I suspect you can simplify the above to:
(eval-and-compile (set-buffer "*Messages*"))
;; Hereafter is ignored when byte-compiled.
(message "Hello, world.")
> Stefan, any ideas? I think switching to a different buffer inside
> `eval-and-compile` is a bad idea, but maybe I'm missing something.
I tend to agree.
[ Side note: (push user-emacs-directory load-path) is also a bad idea. ]
We could guard against this to some extent, but there will always be
ways for the code executed at compile-time to mess up the state of
the compiler, so I'm not sure where we should draw the line.
FWIW, in my book `set-buffer` is a code smell (usually better replaced
by `with-current-buffer`).
Admittedly, the resulting behavior can be very puzzling&frustrating for
the user, which would tend to argue in favor of trying to at least
detect the problem.
But note that if the code switched to a buffer where point is not at
EOB, we'd probably get helpful error messages during compilation, so
I'm leaning towards considering it a "minor corner case" issue, but
I think the untested patch below would be enough to plug the hole.
Stefan
diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 5df1205869c..e22ab94e378 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -2376,7 +2376,10 @@ byte-compile-from-buffer
(form (read-positioning-symbols inbuffer))
(warning (byte-run--unescaped-character-literals-warning)))
(when warning (byte-compile-warn-x form "%s" warning))
- (byte-compile-toplevel-file-form form)))
+ ;; Defend against macros using `set-buffer' or `goto-char'
+ ;; bug#62317.
+ (save-excursion
+ (byte-compile-toplevel-file-form form))))
;; Compile pending forms at end of file.
(byte-compile-flush-pending)
(byte-compile-warn-about-unresolved-functions)))
next prev parent reply other threads:[~2023-04-01 16:27 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-21 3:54 bug#62317: 28.2; This byte-compiled file behaves wrongly Teika Kazura
2023-03-22 6:39 ` bug#62317: bug #62317: " Teika Kazura
2023-03-28 9:15 ` Teika Kazura
2023-03-28 12:08 ` Eli Zaretskii
2023-03-28 12:43 ` Andrea Corallo
2023-03-28 12:53 ` Eli Zaretskii
2023-03-28 13:49 ` Andrea Corallo
2023-03-30 9:20 ` Teika Kazura
2023-03-30 9:41 ` Eli Zaretskii
2023-04-01 7:36 ` Teika Kazura
2023-04-01 8:08 ` Eli Zaretskii
2023-04-01 16:27 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2023-04-01 17:10 ` bug#62317: " Eli Zaretskii
2023-04-01 23:09 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-04-02 5:17 ` Eli Zaretskii
2023-09-12 0:08 ` Stefan Kangas
2023-09-12 18:12 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-13 14:02 ` Stefan Kangas
2023-09-13 14:45 ` Eli Zaretskii
2023-09-13 15:46 ` Stefan Kangas
2023-04-01 23:15 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-09-12 0:09 ` Stefan Kangas
2023-04-05 4:12 ` bug#62317: bug #62317: " Teika Kazura
[not found] ` <handler.62317.C.169462003624017.notifdonectrl.0@debbugs.gnu.org>
2023-09-14 6:35 ` bug#62317: acknowledged by developer Teika Kazura
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