From: Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: rgm@gnu.org, stefan@marxist.se, contovob@tcd.ie,
dick.r.chiang@gmail.com, 46722@debbugs.gnu.org, larsi@gnus.org
Subject: bug#46722: test-map-into fails
Date: Wed, 05 Jan 2022 13:24:40 -0500 [thread overview]
Message-ID: <jwvtueiqcbp.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <83a6ga9hu1.fsf@gnu.org> (Eli Zaretskii's message of "Wed, 05 Jan 2022 20:07:50 +0200")
> Is it? how so? copy-sequence is not a trivial operation, at least not
> with arbitrary data structures.
This is used on the `key` argument of `gethash/puthash` on a hash-table
defined to use `:test #'equal`. And it is used on a value which is
defined to be a list.
For this reason, I think it is very safe.
The reason why the current code only misfires "rarely" is that in most
cases, when we change by side-effect an object that's a key in an
`equal` hashtable, the result is a hashtable where this entry can't be
found (because its hash doesn't match any more), so we end up
luckily not making use of this (now broken) entry.
So the underlying bug only appears if either the hash-table is rehashed
or the new `sxhash-equal` value happens to the same as the old one.
> And we nowadays use generics a lot, so this could potentially affect
> gobs of code. So I'd rather we didn't install this on the
> release branch.
Fine by me,
Stefan
next prev parent reply other threads:[~2022-01-05 18:24 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 16:22 bug#46722: test-map-into fails Glenn Morris
2021-02-23 16:33 ` Basil L. Contovounesios
2021-02-23 17:06 ` Glenn Morris
2021-02-23 17:30 ` Stefan Monnier
2021-02-23 20:58 ` Basil L. Contovounesios
2021-02-23 22:50 ` Basil L. Contovounesios
2021-04-04 16:05 ` Glenn Morris
2021-11-17 8:47 ` Stefan Kangas
2021-11-29 18:20 ` Glenn Morris
2021-11-29 18:26 ` Lars Ingebrigtsen
2021-11-29 18:40 ` Glenn Morris
2022-01-04 21:56 ` dick
2022-01-05 14:01 ` dick
2022-01-05 16:31 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-01-05 17:51 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-01-05 18:07 ` Eli Zaretskii
2022-01-05 18:24 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors [this message]
2022-01-13 19:23 ` Philipp Stephani
2022-01-13 20:40 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-01-13 20:45 ` Philipp Stephani
2022-01-14 7:40 ` Lars Ingebrigtsen
2022-01-14 12:02 ` Philipp Stephani
2022-01-15 8:01 ` Lars Ingebrigtsen
2022-01-15 11:47 ` Philipp Stephani
2022-01-15 15:16 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-01-15 15:55 ` Eli Zaretskii
2022-01-20 12:49 ` Lars Ingebrigtsen
2022-01-05 15:17 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-01-05 16:04 ` dick
2022-01-05 16:38 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-01-05 18:35 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-01-05 18:59 ` dick
2022-01-05 19:17 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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