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Bug 347810

Summary: dev-libs/libgcrypt-1.4.6 QA rijndael.c warning: dereferencing type-punned pointer will break strict-aliasing rules
Product: Gentoo Linux Reporter: David J Cozatt <djcozatt>
Component: Current packagesAssignee: Crypto team [DISABLED] <crypto+disabled>
Severity: normal    
Priority: High    
Version: unspecified   
Hardware: All   
OS: Linux   
Package list:
Runtime testing required: ---
Attachments: build log

Description David J Cozatt 2010-12-05 13:14:33 UTC
QA: other                                                                     │
│QA Notice: Package has poor programming practices which may compile           │
│           fine but exhibit random runtime failures.                          │
│rijndael.c:325:3: warning: dereferencing type-punned pointer will break   
   strict-aliasing rules                                                         │
│rijndael.c:325:3: warning: dereferencing type-punned pointer will break       │
│strict-aliasing rules                                                         │
│rijndael.c:348:7: warning: dereferencing type-punned pointer will break       │
│strict-aliasing rules                                                         │
│rijndael.c:372:3: warning: dereferencing type-punned pointer will break       │
│strict-aliasing rules                                                         │
│rijndael.c:586:3: warning: dereferencing type-punned pointer will break    

strict-aliasing rules                                                         │
│rijndael.c:610:7: warning: dereferencing type-punned pointer will break       │
│strict-aliasing rules                                                         │
│rijndael.c:633:3: warning: dereferencing type-punned pointer will break       │
│strict-aliasing rules                                                         │
│rijndael.c:653:3: warning: dereferencing type-punned pointer will break       │
│strict-aliasing rules

Dereferencing pointer type punned will break strict-aliasing rules

A quote:
<< The most common warning you will see is probably "dereferencing type-
punned pointer will break strict-aliasing rules".  The place where it
warns is in general not wrong -- what gcc tries to tell you is that you
will break the aliasing rules when you dereference the pointer later
(unless you cast it back to its original type first).  This warning
should be interpreted as saying that your interfaces are badly designed,
and the correct way to avoid the warning is to redesign them in a way
where you do not need to cast between conflicting types.  (Even if you
often can make this warning go away by changing void** to void*...) >>

Please read the actual standard too.  The rules about pointer type
conversions are at  The appropriate paragraphs are paragraphs
1 and 7.

Reproducible: Always

david@random ~ $ emerge --info libgcrypt
Portage (default/linux/amd64/10.0, gcc-4.5.1, glibc-2.12.1-r3, 2.6.36-gentoo-r3 x86_64)
                        System Settings
System uname: Linux-2.6.36-gentoo-r3-x86_64-AMD_Athlon-tm-_64_Processor_3200+-with-gentoo-2.0.1
Timestamp of tree: Sat, 04 Dec 2010 23:45:02 +0000
app-shells/bash:     4.1_p9
dev-java/java-config: 2.1.11-r2
dev-lang/python:     2.6.6-r1, 2.7.1, 3.1.3
dev-util/cmake:      2.8.1-r2
sys-apps/baselayout: 2.0.1-r1
sys-apps/openrc:     0.6.6
sys-apps/sandbox:    2.4
sys-devel/autoconf:  2.13, 2.68
sys-devel/automake:  1.10.3, 1.11.1
sys-devel/binutils:  2.20.1-r1
sys-devel/gcc:       4.4.5, 4.5.1-r1
sys-devel/gcc-config: 1.4.1
sys-devel/libtool:   2.4-r1
sys-devel/make:      3.82
virtual/os-headers: (sys-kernel/linux-headers)
ACCEPT_KEYWORDS="amd64 ~amd64"
CFLAGS="-march=native -O2 -pipe"
CONFIG_PROTECT="/etc /etc/"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo"
CXXFLAGS="-march=native -O2 -pipe"
FEATURES="assume-digests binpkg-logs buildpkg distlocks fixlafiles fixpackages multilib-strict news parallel-fetch protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch"
LDFLAGS="-Wl,--hash-style=gnu,-O1 -Wl,--as-needed"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"
USE="acl alsa amd64 berkdb bzip2 cdr cli cracklib crypt cups cxx dri en fortran gdbm gpm gtk iconv ipv6 midi mmx modules mudflap multilib ncurses nls nptl nptlonly openmp pam pcre perl pic pppd python readline session sse sse2 ssl sysfs tcpd threads unicode xorg zlib" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ubx" INPUT_DEVICES="evdev keyboard mouse" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="en_US" PHP_TARGETS="php5-2" RUBY_TARGETS="ruby18 ree18" USERLAND="GNU" VIDEO_CARDS="nv nvidia vesa nouveau" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" 

                        Package Settings

dev-libs/libgcrypt-1.4.6 was built with the following:
Comment 1 David J Cozatt 2010-12-05 13:16:11 UTC
Created attachment 256393 [details]
build log
Comment 2 Dane Smith (RETIRED) gentoo-dev 2010-12-07 18:19:54 UTC
Please note in the future:

 * Please do not file a Gentoo bug and instead report the above QA
 * issues directly to the upstream developers of this software.
 * Homepage:

Upstream bug filed.

Closing as upstream.