From: Richard Copley <rcopley@gmail.com>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: Eli Zaretskii <eliz@gnu.org>, Emacs Development <emacs-devel@gnu.org>
Subject: Re: C warning in MSYS2 build
Date: Thu, 5 Oct 2017 21:08:06 +0100 [thread overview]
Message-ID: <CAPM58oiHS+-52PenZJunFSX2Qw6i03=Yu56kPJ+_sYWBSe6xAA@mail.gmail.com> (raw)
In-Reply-To: <281d43c7-b3a9-be40-a8e7-c8021c286f59@cs.ucla.edu>
On 5 October 2017 at 20:32, Paul Eggert <eggert@cs.ucla.edu> wrote:
> On 10/05/2017 11:54 AM, Eli Zaretskii wrote:
>>
>> Thanks, but it isn't new.
>
> In my experience this kind of warning can appear and vanish almost at whim:
> compiling at a different optimization levels, or changing compilation in
> some other way, can cause GCC to omit or include the warning. So possibly
> Richard wasn't getting the warning a day ago, but got the warning after
> changing from -O2 to -O0 (or whatever), or by upgrading GCC.
>
> If it's a major annoyance we could disable --Wnull-dereference for indent.c.
> I hope that's not needed, though.
>
> Come to think of it, last year I filed a GCC bug report about a similar
> problem with lib-src/etags.c and -Wnull-dereference, here:
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71157
>
> The GCC bug is not fixed yet. etags.c confused GCC by using an assignment
> inside an 'if' expression, which is contrary to the usual GNU style, and
> last year I worked around the GCC bug by changing etags.c to use a cleaner
> style. I notice that indent.c also has an assignment inside an 'if'
> expression that is relevant to these warnings. Richard, does it help to
> recode indent.c to use the usual GNU style, as in the attached patch? If so,
> let's do that instead. (Perhaps we should do that anyway....)
Thanks Eli and Paul.
The warnings don't change with that patch.
FWIW it seems to me that the results of the buffer_display_table calls
in c_string_width and lisp_string_width are dereferenced unchecked,
in character.c.
next prev parent reply other threads:[~2017-10-05 20:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-05 17:44 C warning in MSYS2 build Richard Copley
2017-10-05 18:54 ` Eli Zaretskii
2017-10-05 19:32 ` Paul Eggert
2017-10-05 20:08 ` Richard Copley [this message]
2017-10-05 22:44 ` Paul Eggert
2017-10-06 15:16 ` Richard Stallman
2017-10-06 17:23 ` Richard Copley
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