* New warning
[not found] <87fs74k8zq.fsf.ref@yahoo.com>
@ 2023-06-06 13:36 ` Po Lu
2023-06-06 15:59 ` Eshel Yaron
0 siblings, 1 reply; 7+ messages in thread
From: Po Lu @ 2023-06-06 13:36 UTC (permalink / raw)
To: emacs-devel
Since a previous commit, I get:
../../emacs/src/window.c: In function ‘window_wants_header_line’:
../../emacs/src/window.c:5546:19: warning: potential null pointer dereference [-Wnull-dereference]
5546 | || !null_header_line_format (BVAR (XBUFFER (WINDOW_BUFFER (w)),
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5547 | header_line_format), f))
| ~~~~~~~~~~~~~~~~~~~~~~~
Would someone please look into this?
Thanks.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: New warning
2023-06-06 13:36 ` New warning Po Lu
@ 2023-06-06 15:59 ` Eshel Yaron
2023-06-06 16:14 ` Eli Zaretskii
0 siblings, 1 reply; 7+ messages in thread
From: Eshel Yaron @ 2023-06-06 15:59 UTC (permalink / raw)
To: Po Lu; +Cc: emacs-devel
Po Lu <luangruo@yahoo.com> writes:
> Since a previous commit, I get:
>
> ../../emacs/src/window.c: In function ‘window_wants_header_line’:
> ../../emacs/src/window.c:5546:19: warning: potential null pointer dereference [-Wnull-dereference]
> 5546 | || !null_header_line_format (BVAR (XBUFFER (WINDOW_BUFFER (w)),
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 5547 | header_line_format), f))
> | ~~~~~~~~~~~~~~~~~~~~~~~
>
> Would someone please look into this?
> Thanks.
Hmm, clang doesn't emit this warning (and I didn't try compiling with
gcc before submitting that patch, sorry about that).
The following seems to silence this warning with gcc 13.1, but I'm not
sure I fully understand why/when WINDOW_BUFFER might return NULL, so I'm
not sure it's the right thing to do... Any insights?
diff --git a/src/window.c b/src/window.c
index 81578375498..644fcab9d04 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5540,6 +5540,7 @@ window_wants_header_line (struct window *w)
&& !WINDOW_PSEUDO_P (w)
&& !EQ (window_header_line_format, Qnone)
&& (!null_header_line_format (window_header_line_format, f)
+ || !WINDOW_BUFFER (w)
|| !null_header_line_format (BVAR (XBUFFER (WINDOW_BUFFER (w)),
header_line_format), f))
&& (WINDOW_PIXEL_HEIGHT (w)
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: New warning
2023-06-06 15:59 ` Eshel Yaron
@ 2023-06-06 16:14 ` Eli Zaretskii
2023-06-06 16:41 ` Eli Zaretskii
0 siblings, 1 reply; 7+ messages in thread
From: Eli Zaretskii @ 2023-06-06 16:14 UTC (permalink / raw)
To: Eshel Yaron; +Cc: luangruo, emacs-devel
> From: Eshel Yaron <me@eshelyaron.com>
> Cc: emacs-devel@gnu.org
> Date: Tue, 06 Jun 2023 18:59:14 +0300
>
> Po Lu <luangruo@yahoo.com> writes:
>
> > Since a previous commit, I get:
> >
> > ../../emacs/src/window.c: In function ‘window_wants_header_line’:
> > ../../emacs/src/window.c:5546:19: warning: potential null pointer dereference [-Wnull-dereference]
> > 5546 | || !null_header_line_format (BVAR (XBUFFER (WINDOW_BUFFER (w)),
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > 5547 | header_line_format), f))
> > | ~~~~~~~~~~~~~~~~~~~~~~~
> >
> > Would someone please look into this?
> > Thanks.
>
> Hmm, clang doesn't emit this warning (and I didn't try compiling with
> gcc before submitting that patch, sorry about that).
>
> The following seems to silence this warning with gcc 13.1, but I'm not
> sure I fully understand why/when WINDOW_BUFFER might return NULL, so I'm
> not sure it's the right thing to do... Any insights?
WINDOW_BUFFER returns a Lisp object, so using !WINDOW_BUFFER is wrong
(and will cause compilation errors with some configure options). You
want to use either BUFFERP (WINDOW_BUFFER (w)) or
NILP (WINDOW_BUFFER (w)).
In which case this is AFAIU a bogus warning, since we already test
WINDOW_LEAF_P. So I'm not sure what exactly did GCC see there (my
version of GCC doesn't emit any warnings there). And I don't know how
to ask GCC which part triggered the warning.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: New warning
2023-06-06 16:14 ` Eli Zaretskii
@ 2023-06-06 16:41 ` Eli Zaretskii
2023-06-06 17:53 ` Andreas Schwab
2023-06-06 23:26 ` Po Lu
0 siblings, 2 replies; 7+ messages in thread
From: Eli Zaretskii @ 2023-06-06 16:41 UTC (permalink / raw)
To: luangruo; +Cc: me, emacs-devel
> Date: Tue, 06 Jun 2023 19:14:11 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: luangruo@yahoo.com, emacs-devel@gnu.org
>
> > From: Eshel Yaron <me@eshelyaron.com>
> > Cc: emacs-devel@gnu.org
> > Date: Tue, 06 Jun 2023 18:59:14 +0300
> >
> > Po Lu <luangruo@yahoo.com> writes:
> >
> > > Since a previous commit, I get:
> > >
> > > ../../emacs/src/window.c: In function ‘window_wants_header_line’:
> > > ../../emacs/src/window.c:5546:19: warning: potential null pointer dereference [-Wnull-dereference]
> > > 5546 | || !null_header_line_format (BVAR (XBUFFER (WINDOW_BUFFER (w)),
> > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > 5547 | header_line_format), f))
> > > | ~~~~~~~~~~~~~~~~~~~~~~~
I've now tried on two different systems, with and without
optimizations, with GCC 9.2 and 11.3, and none of those produce this
warning. What version of GCC do you have there, Po Lu?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: New warning
2023-06-06 16:41 ` Eli Zaretskii
@ 2023-06-06 17:53 ` Andreas Schwab
2023-06-06 18:30 ` Eli Zaretskii
2023-06-06 23:26 ` Po Lu
1 sibling, 1 reply; 7+ messages in thread
From: Andreas Schwab @ 2023-06-06 17:53 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: luangruo, me, emacs-devel
On Jun 06 2023, Eli Zaretskii wrote:
> I've now tried on two different systems, with and without
> optimizations, with GCC 9.2 and 11.3, and none of those produce this
> warning.
Did you configure with --enable-checking? Try without.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: New warning
2023-06-06 17:53 ` Andreas Schwab
@ 2023-06-06 18:30 ` Eli Zaretskii
0 siblings, 0 replies; 7+ messages in thread
From: Eli Zaretskii @ 2023-06-06 18:30 UTC (permalink / raw)
To: Andreas Schwab; +Cc: luangruo, me, emacs-devel
> From: Andreas Schwab <schwab@linux-m68k.org>
> Cc: luangruo@yahoo.com, me@eshelyaron.com, emacs-devel@gnu.org
> Date: Tue, 06 Jun 2023 19:53:44 +0200
>
> On Jun 06 2023, Eli Zaretskii wrote:
>
> > I've now tried on two different systems, with and without
> > optimizations, with GCC 9.2 and 11.3, and none of those produce this
> > warning.
>
> Did you configure with --enable-checking? Try without.
Thanks. Stupid GCC.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: New warning
2023-06-06 16:41 ` Eli Zaretskii
2023-06-06 17:53 ` Andreas Schwab
@ 2023-06-06 23:26 ` Po Lu
1 sibling, 0 replies; 7+ messages in thread
From: Po Lu @ 2023-06-06 23:26 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: me, emacs-devel
Eli Zaretskii <eliz@gnu.org> writes:
>> Date: Tue, 06 Jun 2023 19:14:11 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: luangruo@yahoo.com, emacs-devel@gnu.org
>>
>> > From: Eshel Yaron <me@eshelyaron.com>
>> > Cc: emacs-devel@gnu.org
>> > Date: Tue, 06 Jun 2023 18:59:14 +0300
>> >
>> > Po Lu <luangruo@yahoo.com> writes:
>> >
>> > > Since a previous commit, I get:
>> > >
>> > > ../../emacs/src/window.c: In function ‘window_wants_header_line’:
>> > > ../../emacs/src/window.c:5546:19: warning: potential null pointer dereference [-Wnull-dereference]
>> > > 5546 | || !null_header_line_format (BVAR (XBUFFER (WINDOW_BUFFER (w)),
>> > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > > 5547 | header_line_format), f))
>> > > | ~~~~~~~~~~~~~~~~~~~~~~~
>
> I've now tried on two different systems, with and without
> optimizations, with GCC 9.2 and 11.3, and none of those produce this
> warning. What version of GCC do you have there, Po Lu?
GCC 13.1.1.
Thanks.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-06-06 23:26 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <87fs74k8zq.fsf.ref@yahoo.com>
2023-06-06 13:36 ` New warning Po Lu
2023-06-06 15:59 ` Eshel Yaron
2023-06-06 16:14 ` Eli Zaretskii
2023-06-06 16:41 ` Eli Zaretskii
2023-06-06 17:53 ` Andreas Schwab
2023-06-06 18:30 ` Eli Zaretskii
2023-06-06 23:26 ` Po Lu
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