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Subject: |
29.0.50; Uninitialised variable warning in src/term.c |
|
Date: |
Thu, 07 Oct 2021 12:18:14 +0100 |
Severity: minor
I'm currently seeing the following warning with GCC 10.3.0:
In file included from term.c:30:
term.c: In function ‘encode_terminal_code’:
lisp.h:1853:35: warning: ‘gstring’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
1853 | return XVECTOR (array)->contents[idx];
| ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
term.c:553:16: note: ‘gstring’ was declared here
553 | Lisp_Object gstring;
| ^~~~~~~
I'm guessing it started with the following recent change:
Remove encode_terminal_code UNINITs
7e871dcd27 2021-10-03 17:52:28 -0700
https://git.sv.gnu.org/cgit/emacs.git/commit/?id=7e871dcd27
What's the best way to pacify it? Do we care about doing so in GCC 10?
Is
cmp = composition_table[src->u.cmp.id];
indeed guaranteed to be non-NULL? If so, maybe gstring could be
initialised as nil and then easserted as non-nil in the !cmp branch
(eassuming cmp is non-NULL in the !src->u.cmp.automatic branch does not
make the warning go away). If not, could there indeed be a bug?
Thanks,
--
Basil
In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo version
1.16.0, Xaw3d scroll bars)
of 2021-10-07 built on tia
Repository revision: e338effc774f9a7cfe13d4a35dc1cf493a22c972
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux bookworm/sid
Configured using:
'configure 'CC=ccache gcc' 'CFLAGS=-Og -ggdb3' --config-cache --prefix
/home/blc/.local --enable-checking=structs --with-x-toolkit=lucid
--with-file-notification=yes --with-x'
Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
X11 XAW3D XDBE XIM XPM LUCID ZLIB
Important settings:
value of $LANG: en_IE.UTF-8
value of $XMODIFIERS: @im=ibus
locale-coding-system: utf-8-unix
Major mode: Lisp Interaction
Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
show-paren-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
font-lock-mode: t
blink-cursor-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
line-number-mode: t
indent-tabs-mode: t
transient-mark-mode: t
Load-path shadows:
None found.
Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg rfc6068 epg-config gnus-util rmail
rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json map text-property-search time-date
seq gv subr-x byte-opt bytecomp byte-compile cconv mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode 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 lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock
font-lock syntax font-core term/tty-colors frame minibuffer 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 emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window 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
cairo x-toolkit x multi-tty make-network-process emacs)
Memory information:
((conses 16 50810 6940)
(symbols 48 6621 1)
(strings 32 18974 1858)
(string-bytes 1 613497)
(vectors 16 13616)
(vector-slots 8 184446 10452)
(floats 8 23 47)
(intervals 56 231 0)
(buffers 992 10))
--- End Message ---
--- Begin Message ---
|
Subject: |
Re: bug#51075: 29.0.50; Uninitialised variable warning in src/term.c |
|
Date: |
Thu, 7 Oct 2021 13:13:33 -0700 |
|
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 |
On 10/7/21 06:01, Eli Zaretskii wrote:
It's a bogus warning. It might be worth reporting to the GCC folks
(unless GCC 11 already fixed that).
Yes, I believed it's fixed in GCC 11. GCC 11.2.1 20210728 (Red Hat
11.2.1-1) does not warn me about it.
Feel free to assign some value to gstring in the 'else' clause, to
shut up GCC in this case.
I installed into the emacs-28 branch the attached, which fixes it in a
different way to make it a bit clearer to the reader that we're
pacifying an inadequate compiler rather than executing odd code for an
unknown reason.
There are a handful of other bogus warnings with GCC 11.2.1, which I'll
try to get around to pacifying (I hope before GCC 12 comes out :-).
0001-Pacify-GCC-10.3-Wmaybe-uninitialized.patch
Description: Text Data
--- End Message ---