From: Paul Eggert <eggert@cs.ucla.edu>
To: emacs-devel@gnu.org
Cc: Richard Copley <rcopley@gmail.com>, Eli Zaretskii <eliz@gnu.org>
Subject: Re: C warning in MSYS2 build
Date: Thu, 5 Oct 2017 12:32:26 -0700 [thread overview]
Message-ID: <281d43c7-b3a9-be40-a8e7-c8021c286f59@cs.ucla.edu> (raw)
In-Reply-To: <83inftwhlb.fsf@gnu.org>
[-- Attachment #1: Type: text/plain, Size: 1243 bytes --]
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....)
[-- Attachment #2: indent.diff --]
[-- Type: text/x-patch, Size: 761 bytes --]
diff --git a/src/indent.c b/src/indent.c
index 26507b5eb5..79841a3d2c 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -76,15 +76,17 @@ buffer_display_table (void)
static int
character_width (int c, struct Lisp_Char_Table *dp)
{
- Lisp_Object elt;
-
/* These width computations were determined by examining the cases
in display_text_line. */
/* Everything can be handled by the display table, if it's
present and the element is right. */
- if (dp && (elt = DISP_CHAR_VECTOR (dp, c), VECTORP (elt)))
- return ASIZE (elt);
+ if (dp)
+ {
+ Lisp_Object elt = DISP_CHAR_VECTOR (dp, c);
+ if (VECTORP (elt))
+ return ASIZE (elt);
+ }
/* Some characters are special. */
if (c == '\n' || c == '\t' || c == '\015')
next prev parent reply other threads:[~2017-10-05 19:32 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 [this message]
2017-10-05 20:08 ` Richard Copley
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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