From: Paul Pogonyshev <pogonyshev@gmail.com>
To: 33034@debbugs.gnu.org
Subject: bug#33034: `unwind-protect' cleanup form is not executed if body dies in stack overflow
Date: Sat, 13 Oct 2018 12:07:48 +0200 [thread overview]
Message-ID: <CAG7BparyujS9CKTv54N-brS_KMu5H=XY3KjhQoS3nRD_rZ-L9A@mail.gmail.com> (raw)
To reproduce:
(defun overflow ()
(overflow))
(defun test ()
(interactive)
(message "BEFORE")
(unwind-protect
(overflow)
(message "CLEANUP")))
Invocation of `test' never issues message "CLEANUP", whether it is run
interactively or non-interactively.
By comparison, if you _catch_ the error with `condition-case':
(defun test-2 ()
(interactive)
(message "BEFORE")
(unwind-protect
(ignore-errors (overflow))
(message "CLEANUP")))
then cleanup form is executed properly.
But if your error catcher is "above" the `unwind-protect' form, the
cleanup is not executed again, even though the error is eaten as
expected:
(defun test-3 ()
(interactive)
(message "BEFORE")
(ignore-errors
(unwind-protect
(overflow)
(message "CLEANUP"))))
This is a perfect way to screw up your Emacs permanently (until full
restart): when some `unwind-protect' cleanups are not run, you can be
left with unexpected function advices, permanently altered global
state etc., without any good way to undestand what's wrong.
Paul
next reply other threads:[~2018-10-13 10:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-13 10:07 Paul Pogonyshev [this message]
2018-10-13 10:29 ` bug#33034: `unwind-protect' cleanup form is not executed if body dies in stack overflow Eli Zaretskii
2018-10-13 10:35 ` Paul Pogonyshev
2018-10-13 10:45 ` Eli Zaretskii
2018-10-13 10:52 ` Paul Pogonyshev
2018-10-13 11:01 ` Eli Zaretskii
2018-10-13 11:29 ` Eli Zaretskii
2018-10-13 11:38 ` Paul Pogonyshev
2018-10-13 12:35 ` Eli Zaretskii
2018-10-13 14:02 ` Paul Pogonyshev
2018-10-14 17:02 ` Paul Eggert
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