bug#32444: 27.0.50; lisp.h XCAR compilatiob warning

bug#32444: 27.0.50; lisp.h XCAR compilatiob warning

[Live System User]

Hi,

        Compilation gives various warnings:

In file included from dbusbind.c:26:0:
dbusbind.c: In function ‘xd_signature’:
lisp.h:379:38: warning: potential null pointer dereference [-Wnull-dereference]
 #define lisp_h_XCAR(c) XCONS (c)->u.s.car
                        ~~~~~~~~~~~~~~^~
lisp.h:1280:10: note: in expansion of macro ‘lisp_h_XCAR’
   return lisp_h_XCAR (c);
          ^~~~~~~~~~~

          Thanks.




In GNU Emacs 27.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.20.10)
 of 2018-08-14 built on localhost.localdomain
Repository revision: 5620d591ee67e5b31ca8d5aa0dcc1a13116b09a7
Windowing system distributor 'Fedora Project', version 11.0.11803000
System Description: Fedora 24 (Workstation Edition)

Recent messages:
354 Ok Send data ending with <CRLF>.<CRLF>
Sending email 
250 OK , completed
Sending email done
221 Service Closing transmission
Sending...done
mwheel-scroll: End of buffer [2 times]
help-follow-mouse: No cross-reference here
Mark set [2 times]
previous-line: Beginning of buffer [9 times]
previous-line: Beginning of buffer
Configured using:
 'configure 'CFLAGS=-DMAIL_USE_LOCKF -O0 -ggdb3 -pipe -Wall
 -Werror=format-security -fexceptions -fstack-protector-strong
 --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic'
 LDFLAGS=-Wl,-z,relro --disable-dependency-tracking
 --prefix=/tmp/emacs-27.0-git-master
 --with-dbus --with-gif --with-jpeg --with-png --with-rsvg --with-lcms2
 --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3 --with-gpm=yes
 --with-xwidgets --with-modules --with-json'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES THREADS XWIDGETS JSON LCMS2 GMP

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  gnus-desktop-notify-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(mailalias smtpmail novice pp shadow sort mail-extr emacsbug help-fns
radix-tree cl-print debug backtrace cus-start timezone utf-7 nnfolder
nnagent nnml gnutls network-stream nsm gnus-agent gnus-srvr gnus-score
score-mode nnvirtual gnus-msg gnus-cache gnus-demon nntp
gnus-desktop-notify notifications dbus xml epa-file nnreddit gnus-art
mm-uu mml2015 cl sieve sieve-mode sieve-manage sasl sasl-anonymous
sasl-login sasl-plain advice nnir gnus-sum gnus-group mm-url gnus-undo
gnus-start gnus-cloud nnimap nnmail mail-source imap rfc2104 utf7 netrc
parse-time gnus-spec gnus-int gnus-range gnus-win gnus message rmc puny
dired desktop frameset edmacro kmacro dired-loaddefs subr-x format-spec
rfc822 mml url url-proxy url-privacy url-expand url-methods url-history
url-cookie url-domsuf url-util url-parse auth-source eieio eieio-core
eieio-loaddefs json rx map url-vars mm-view mml-smime smime dig mailcap
mml-sec password-cache epa epg cl-extra help-mode easymenu epg-config
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev sendmail
derived gmm-utils mailheader seq byte-opt bytecomp byte-compile cconv
wid-edit nnoo nnheader gnus-util rmail dframe rmail-loaddefs rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils misearch multi-isearch
elec-pair cl-seq easy-mmode cl-macs inline cl-loaddefs cl-lib gv pcase
time-date mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
xwidget-internal move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 851994 71946)
 (symbols 48 127392 27)
 (strings 32 106029 5199)
 (string-bytes 1 4104892)
 (vectors 16 11881)
 (vector-slots 8 573706 25598)
 (floats 8 273 798)
 (intervals 56 10266 32)
 (buffers 992 39)
 (heap 1024 75735 21342))

bug#32444: 27.0.50; lisp.h XCAR compilatiob warning

[Lars Ingebrigtsen]

Live System User <nyc4bos@aol.com> writes:

>         Compilation gives various warnings:
>
> In file included from dbusbind.c:26:0:
> dbusbind.c: In function ‘xd_signature’:
> lisp.h:379:38: warning: potential null pointer dereference [-Wnull-dereference]
>  #define lisp_h_XCAR(c) XCONS (c)->u.s.car
>                         ~~~~~~~~~~~~~~^~
> lisp.h:1280:10: note: in expansion of macro ‘lisp_h_XCAR’
>    return lisp_h_XCAR (c);
>           ^~~~~~~~~~~

Yes, I'm seeing the same thing.  Is this due to an old version of gcc or
something?  I'm using "gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516".

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#32444: 27.0.50; lisp.h XCAR compilatiob warning

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Live System User <nyc4bos@aol.com> writes:
>
>>         Compilation gives various warnings:
>>
>> In file included from dbusbind.c:26:0:
>> dbusbind.c: In function ‘xd_signature’:
>> lisp.h:379:38: warning: potential null pointer dereference [-Wnull-dereference]
>>  #define lisp_h_XCAR(c) XCONS (c)->u.s.car
>>                         ~~~~~~~~~~~~~~^~
>> lisp.h:1280:10: note: in expansion of macro ‘lisp_h_XCAR’
>>    return lisp_h_XCAR (c);
>>           ^~~~~~~~~~~
>
> Yes, I'm seeing the same thing.  Is this due to an old version of gcc or
> something?  I'm using "gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516".

Yes, it's not present with a newer gcc, so this is a known issue (and it
sounds like it won't be fixed (from when I reported a similar thing)),
so I'm closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no