* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
@ 2016-12-11 9:41 Philipp
2016-12-11 18:38 ` Glenn Morris
0 siblings, 1 reply; 15+ messages in thread
From: Philipp @ 2016-12-11 9:41 UTC (permalink / raw)
To: 25166
You can set the function cell of nil and t using `fset' and friends.
But you can't call the `nil' function using (nil) (it does work with
(t)). I think that attempting to set the function cell of nil and t is
almost always a bug -- probably the programmer wanted to set a real
symbol, but some of the constants got passed. I propose to signal an
error (e.g. `setting-constant') whenever the function cell of nil and t
is modified; maybe the same should happen for keywords.
In GNU Emacs 26.0.50.5 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
of 2016-12-10 built on localhost
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^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-11 9:41 bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t Philipp
@ 2016-12-11 18:38 ` Glenn Morris
2016-12-12 20:25 ` Glenn Morris
0 siblings, 1 reply; 15+ messages in thread
From: Glenn Morris @ 2016-12-11 18:38 UTC (permalink / raw)
To: Philipp; +Cc: 25166
Philipp wrote:
> You can set the function cell of nil and t using `fset' and friends.
> But you can't call the `nil' function using (nil) (it does work with
> (t)). I think that attempting to set the function cell of nil and t is
> almost always a bug -- probably the programmer wanted to set a real
> symbol, but some of the constants got passed. I propose to signal an
> error (e.g. `setting-constant') whenever the function cell of nil and t
> is modified; maybe the same should happen for keywords.
I just did this yesterday...
See https://debbugs.gnu.org/25110, ba8e883, and 3fd4433.
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-11 18:38 ` Glenn Morris
@ 2016-12-12 20:25 ` Glenn Morris
2016-12-26 19:29 ` Philipp Stephani
0 siblings, 1 reply; 15+ messages in thread
From: Glenn Morris @ 2016-12-12 20:25 UTC (permalink / raw)
To: Philipp; +Cc: 25166
Glenn Morris wrote:
> Philipp wrote:
>
>> You can set the function cell of nil and t using `fset' and friends.
>> But you can't call the `nil' function using (nil) (it does work with
>> (t)). I think that attempting to set the function cell of nil and t is
>> almost always a bug -- probably the programmer wanted to set a real
>> symbol, but some of the constants got passed. I propose to signal an
>> error (e.g. `setting-constant') whenever the function cell of nil and t
>> is modified; maybe the same should happen for keywords.
>
> I just did this yesterday...
> See https://debbugs.gnu.org/25110, ba8e883, and 3fd4433.
And now see also ffb1302. :)
Anyway, I only did "nil", since as you say "t" can actually be called as
a function. But you are right that it's probably unintended.
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-12 20:25 ` Glenn Morris
@ 2016-12-26 19:29 ` Philipp Stephani
2016-12-26 19:41 ` Philipp Stephani
2016-12-26 19:47 ` Eli Zaretskii
0 siblings, 2 replies; 15+ messages in thread
From: Philipp Stephani @ 2016-12-26 19:29 UTC (permalink / raw)
To: Glenn Morris; +Cc: 25166
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Glenn Morris <rgm@gnu.org> schrieb am Mo., 12. Dez. 2016 um 21:25 Uhr:
> Glenn Morris wrote:
>
> > Philipp wrote:
> >
> >> You can set the function cell of nil and t using `fset' and friends.
> >> But you can't call the `nil' function using (nil) (it does work with
> >> (t)). I think that attempting to set the function cell of nil and t is
> >> almost always a bug -- probably the programmer wanted to set a real
> >> symbol, but some of the constants got passed. I propose to signal an
> >> error (e.g. `setting-constant') whenever the function cell of nil and t
> >> is modified; maybe the same should happen for keywords.
> >
> > I just did this yesterday...
> > See https://debbugs.gnu.org/25110, ba8e883, and 3fd4433.
>
> And now see also ffb1302. :)
> Anyway, I only did "nil", since as you say "t" can actually be called as
> a function. But you are right that it's probably unintended.
>
>
Thanks! Interestingly the behavior was already added in 1994 (commit
c15c5d408d696928862ca2848a359231e373556c), but apparently reverted later.
I'd suggest to simply reinstate that commit.
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^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-26 19:29 ` Philipp Stephani
@ 2016-12-26 19:41 ` Philipp Stephani
2016-12-26 19:47 ` Eli Zaretskii
1 sibling, 0 replies; 15+ messages in thread
From: Philipp Stephani @ 2016-12-26 19:41 UTC (permalink / raw)
To: Glenn Morris; +Cc: 25166
[-- Attachment #1.1: Type: text/plain, Size: 1205 bytes --]
Philipp Stephani <p.stephani2@gmail.com> schrieb am Mo., 26. Dez. 2016 um
20:29 Uhr:
> Glenn Morris <rgm@gnu.org> schrieb am Mo., 12. Dez. 2016 um 21:25 Uhr:
>
> Glenn Morris wrote:
>
> > Philipp wrote:
> >
> >> You can set the function cell of nil and t using `fset' and friends.
> >> But you can't call the `nil' function using (nil) (it does work with
> >> (t)). I think that attempting to set the function cell of nil and t is
> >> almost always a bug -- probably the programmer wanted to set a real
> >> symbol, but some of the constants got passed. I propose to signal an
> >> error (e.g. `setting-constant') whenever the function cell of nil and t
> >> is modified; maybe the same should happen for keywords.
> >
> > I just did this yesterday...
> > See https://debbugs.gnu.org/25110, ba8e883, and 3fd4433.
>
> And now see also ffb1302. :)
> Anyway, I only did "nil", since as you say "t" can actually be called as
> a function. But you are right that it's probably unintended.
>
>
> Thanks! Interestingly the behavior was already added in 1994 (commit
> c15c5d408d696928862ca2848a359231e373556c), but apparently reverted later.
> I'd suggest to simply reinstate that commit.
>
Here's a patch.
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From 5e47f4f2af44285fc877906c5c7689f66e80baf6 Mon Sep 17 00:00:00 2001
From: Philipp Stephani <phst@google.com>
Date: Mon, 26 Dec 2016 20:38:04 +0100
Subject: [PATCH] Prevent setting the function cell of t (Bug#25166)
Restore behavior of commit c15c5d408d696928862ca2848a359231e373556c,
and make 'fset' consistent with 'fmakunbound'.
* src/data.c (Ffset): Also disallow setting the function cell of t.
* test/src/data-tests.el (data-tests-fset-fmakunbound): Add unit test.
---
src/data.c | 2 +-
test/src/data-tests.el | 7 +++++++
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/data.c b/src/data.c
index 821fc37937..0fe4bdf590 100644
--- a/src/data.c
+++ b/src/data.c
@@ -734,7 +734,7 @@ DEFUN ("fset", Ffset, Sfset, 2, 2, 0,
register Lisp_Object function;
CHECK_SYMBOL (symbol);
/* Perhaps not quite the right error signal, but seems good enough. */
- if (NILP (symbol))
+ if (NILP (symbol) || EQ (symbol, Qt))
xsignal1 (Qsetting_constant, symbol);
function = XSYMBOL (symbol)->function;
diff --git a/test/src/data-tests.el b/test/src/data-tests.el
index 757522e399..2daba91b8f 100644
--- a/test/src/data-tests.el
+++ b/test/src/data-tests.el
@@ -450,3 +450,10 @@ binding-test-some-local
(remove-variable-watcher 'data-tests-lvar collect-watch-data)
(setq data-tests-lvar 6)
(should (null watch-data)))))
+
+(ert-deftest data-tests-fset-fmakunbound ()
+ "Test that Bug#25166 is fixed."
+ (should-error (fset nil #'car) :type 'setting-constant)
+ (should-error (fset t #'car) :type 'setting-constant)
+ (should-error (fmakunbound nil) :type 'setting-constant)
+ (should-error (fmakunbound t) :type 'setting-constant))
--
2.11.0
^ permalink raw reply related [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-26 19:29 ` Philipp Stephani
2016-12-26 19:41 ` Philipp Stephani
@ 2016-12-26 19:47 ` Eli Zaretskii
2016-12-27 15:15 ` Stefan Monnier
1 sibling, 1 reply; 15+ messages in thread
From: Eli Zaretskii @ 2016-12-26 19:47 UTC (permalink / raw)
To: Philipp Stephani, Stefan Monnier; +Cc: 25166
> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Mon, 26 Dec 2016 19:29:17 +0000
> Cc: 25166@debbugs.gnu.org
>
> And now see also ffb1302. :)
> Anyway, I only did "nil", since as you say "t" can actually be called as
> a function. But you are right that it's probably unintended.
>
> Thanks! Interestingly the behavior was already added in 1994 (commit
> c15c5d408d696928862ca2848a359231e373556c), but apparently reverted later. I'd suggest to simply
> reinstate that commit.
It was reverted in 32e5c58ca969ec30d31520da52c9866cafa62927. Perhaps
Stefan could tell why he did that (the log message doesn't say).
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-26 19:47 ` Eli Zaretskii
@ 2016-12-27 15:15 ` Stefan Monnier
2016-12-27 22:49 ` Eli Zaretskii
0 siblings, 1 reply; 15+ messages in thread
From: Stefan Monnier @ 2016-12-27 15:15 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: Philipp Stephani, 25166
> It was reverted in 32e5c58ca969ec30d31520da52c9866cafa62927. Perhaps
> Stefan could tell why he did that (the log message doesn't say).
Because there doesn't seem to be any good reason to single out nil and
t in this respect and because those things aren't terribly dangerous.
Stefan
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-27 15:15 ` Stefan Monnier
@ 2016-12-27 22:49 ` Eli Zaretskii
2016-12-27 23:11 ` Stefan Monnier
0 siblings, 1 reply; 15+ messages in thread
From: Eli Zaretskii @ 2016-12-27 22:49 UTC (permalink / raw)
To: Stefan Monnier; +Cc: p.stephani2, 25166
> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Cc: Philipp Stephani <p.stephani2@gmail.com>, rgm@gnu.org,
> 25166@debbugs.gnu.org
> Date: Tue, 27 Dec 2016 10:15:29 -0500
>
> > It was reverted in 32e5c58ca969ec30d31520da52c9866cafa62927. Perhaps
> > Stefan could tell why he did that (the log message doesn't say).
>
> Because there doesn't seem to be any good reason to single out nil and
> t in this respect and because those things aren't terribly dangerous.
So therefore we shouldn't reinstate that now.
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-27 22:49 ` Eli Zaretskii
@ 2016-12-27 23:11 ` Stefan Monnier
2017-05-01 14:44 ` Philipp Stephani
0 siblings, 1 reply; 15+ messages in thread
From: Stefan Monnier @ 2016-12-27 23:11 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: p.stephani2, 25166
>> Because there doesn't seem to be any good reason to single out nil and
>> t in this respect and because those things aren't terribly dangerous.
> So therefore we shouldn't reinstate that now.
Yes, that's my opinion.
Stefan
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2016-12-27 23:11 ` Stefan Monnier
@ 2017-05-01 14:44 ` Philipp Stephani
2017-05-01 15:12 ` Eli Zaretskii
0 siblings, 1 reply; 15+ messages in thread
From: Philipp Stephani @ 2017-05-01 14:44 UTC (permalink / raw)
To: Stefan Monnier, Eli Zaretskii; +Cc: 25166
[-- Attachment #1: Type: text/plain, Size: 396 bytes --]
Stefan Monnier <monnier@iro.umontreal.ca> schrieb am Mi., 28. Dez. 2016 um
00:11 Uhr:
> >> Because there doesn't seem to be any good reason to single out nil and
> >> t in this respect and because those things aren't terribly dangerous.
> > So therefore we shouldn't reinstate that now.
>
> Yes, that's my opinion.
>
>
>
Well, my opinion is obviously different, so the maintainer should decide.
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^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2017-05-01 14:44 ` Philipp Stephani
@ 2017-05-01 15:12 ` Eli Zaretskii
2017-10-27 17:59 ` Noam Postavsky
0 siblings, 1 reply; 15+ messages in thread
From: Eli Zaretskii @ 2017-05-01 15:12 UTC (permalink / raw)
To: Philipp Stephani; +Cc: 25166, monnier
> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Mon, 01 May 2017 14:44:44 +0000
> Cc: rgm@gnu.org, 25166@debbugs.gnu.org
>
> Stefan Monnier <monnier@iro.umontreal.ca> schrieb am Mi., 28. Dez. 2016 um 00:11 Uhr:
>
> >> Because there doesn't seem to be any good reason to single out nil and
> >> t in this respect and because those things aren't terribly dangerous.
> > So therefore we shouldn't reinstate that now.
>
> Yes, that's my opinion.
>
> Well, my opinion is obviously different, so the maintainer should decide.
One maintainer has already decided, see above.
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2017-05-01 15:12 ` Eli Zaretskii
@ 2017-10-27 17:59 ` Noam Postavsky
2017-10-28 16:16 ` Stefan Monnier
0 siblings, 1 reply; 15+ messages in thread
From: Noam Postavsky @ 2017-10-27 17:59 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: Philipp Stephani, 25166, Stefan Monnier
# fset of nil is already covered in Bug#25110
retitle 25166 It shouldn't be possible to set the function cell of t
tags 25166 wontfix
close 25166
quit
On Mon, May 1, 2017 at 11:12 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Philipp Stephani <p.stephani2@gmail.com>
>> Date: Mon, 01 May 2017 14:44:44 +0000
>> Cc: rgm@gnu.org, 25166@debbugs.gnu.org
>>
>> Stefan Monnier <monnier@iro.umontreal.ca> schrieb am Mi., 28. Dez. 2016 um 00:11 Uhr:
>>
>> >> Because there doesn't seem to be any good reason to single out nil and
>> >> t in this respect and because those things aren't terribly dangerous.
>> > So therefore we shouldn't reinstate that now.
>>
>> Yes, that's my opinion.
>>
>> Well, my opinion is obviously different, so the maintainer should decide.
>
> One maintainer has already decided, see above.
Seems final enough, closing as wontfix.
PS for an example of why singling out nil makes sense (but this
doesn't apply to t) see [1].
Summary: (autoload #'nil "something" nil t) silently succeeds but
makes forward-word, backward-word, etc, (fail to) funcall nil.
[1]: https://github.com/jwiegley/use-package/issues/512
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2017-10-27 17:59 ` Noam Postavsky
@ 2017-10-28 16:16 ` Stefan Monnier
2017-10-28 16:45 ` Noam Postavsky
0 siblings, 1 reply; 15+ messages in thread
From: Stefan Monnier @ 2017-10-28 16:16 UTC (permalink / raw)
To: Noam Postavsky; +Cc: 25166, Philipp Stephani
> PS for an example of why singling out nil makes sense (but this
> doesn't apply to t) see [1].
> Summary: (autoload #'nil "something" nil t) silently succeeds but
> makes forward-word, backward-word, etc, (fail to) funcall nil.
Why would someone do (autoload #'nil "something" nil t) ?
Stefan
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2017-10-28 16:16 ` Stefan Monnier
@ 2017-10-28 16:45 ` Noam Postavsky
2017-10-29 18:10 ` Stefan Monnier
0 siblings, 1 reply; 15+ messages in thread
From: Noam Postavsky @ 2017-10-28 16:45 UTC (permalink / raw)
To: Stefan Monnier; +Cc: 25166, Philipp Stephani
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> PS for an example of why singling out nil makes sense (but this
>> doesn't apply to t) see [1].
>> Summary: (autoload #'nil "something" nil t) silently succeeds but
>> makes forward-word, backward-word, etc, (fail to) funcall nil.
>
> Why would someone do (autoload #'nil "something" nil t) ?
By accident. It's a bug in use-package.
(use-package foo-pkg :commands <commands-to-autoload>)
Creates autoloads for all the commands in <commands-to-autoload>, which
can be a symbol, or a list of symbols. But nil is also a symbol, so
passing an empty list makes an autoload for nil (because use-package
checks for symbolp before listp), rather than making autoloads for 0
commands.
^ permalink raw reply [flat|nested] 15+ messages in thread
* bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t
2017-10-28 16:45 ` Noam Postavsky
@ 2017-10-29 18:10 ` Stefan Monnier
0 siblings, 0 replies; 15+ messages in thread
From: Stefan Monnier @ 2017-10-29 18:10 UTC (permalink / raw)
To: Noam Postavsky; +Cc: 25166, Philipp Stephani
> By accident. It's a bug in use-package.
That's a rare accident, which I assume has been fixed already (if not,
it's another argument in favor of saying that it's not important).
Nothing that warrants adding special error detection.
Stefan
^ permalink raw reply [flat|nested] 15+ messages in thread
end of thread, other threads:[~2017-10-29 18:10 UTC | newest]
Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-12-11 9:41 bug#25166: 26.0.50; It shouldn't be possible to set the function cell of nil and t Philipp
2016-12-11 18:38 ` Glenn Morris
2016-12-12 20:25 ` Glenn Morris
2016-12-26 19:29 ` Philipp Stephani
2016-12-26 19:41 ` Philipp Stephani
2016-12-26 19:47 ` Eli Zaretskii
2016-12-27 15:15 ` Stefan Monnier
2016-12-27 22:49 ` Eli Zaretskii
2016-12-27 23:11 ` Stefan Monnier
2017-05-01 14:44 ` Philipp Stephani
2017-05-01 15:12 ` Eli Zaretskii
2017-10-27 17:59 ` Noam Postavsky
2017-10-28 16:16 ` Stefan Monnier
2017-10-28 16:45 ` Noam Postavsky
2017-10-29 18:10 ` Stefan Monnier
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