From: Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: How to debug erratic specializer behavior of generic functions
Date: Sun, 20 Feb 2022 18:56:40 -0500 [thread overview]
Message-ID: <jwvbkz1p00o.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: 871qzx2jrt.fsf@web.de
> Any hints for where to dig, how to debug, or what could be involved? So
> far I have nothing for emacs -Q, no recipe, that demonstrates the
> behavior (that's why I chose to ask here first before starting a bug
> report).
If you're seeing this with Emacs's code on `master`, then please report
it as a bug. If you're seeing it with Emacs < 29, then
I suggest you try the patch below.
Stefan
diff --git a/lisp/emacs-lisp/cl-generic.el b/lisp/emacs-lisp/cl-generic.el
index 983694204df..5090e060372 100644
--- a/lisp/emacs-lisp/cl-generic.el
+++ b/lisp/emacs-lisp/cl-generic.el
@@ -604,7 +604,9 @@ cl--generic-dispatchers
(defun cl--generic-get-dispatcher (dispatch)
(with-memoization
- (gethash dispatch cl--generic-dispatchers)
+ ;; We need `copy-sequence` here because this `dispatch' object might be
+ ;; modified by side-effect in `cl-generic-define-method' (bug#46722).
+ (gethash (copy-sequence dispatch) cl--generic-dispatchers)
;; (message "cl--generic-get-dispatcher (%S)" dispatch)
(let* ((dispatch-arg (car dispatch))
(generalizers (cdr dispatch))
next prev parent reply other threads:[~2022-02-20 23:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-20 23:36 How to debug erratic specializer behavior of generic functions Michael Heerdegen
2022-02-20 23:56 ` Stefan Monnier via Users list for the GNU Emacs text editor [this message]
2022-02-20 23:58 ` Lars Ingebrigtsen
2022-02-21 0:05 ` Michael Heerdegen
2022-02-21 0:50 ` Michael Heerdegen
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