Bug#1050589: gcc-13: [x32] -fbuiltin-strchr miscompiles

[Thorsten Glaser <tg@mirbsd.de>]

Package: gcc-13
Version: 13.2.0-1
Severity: normal
X-Debbugs-Cc: tg@mirbsd.de

I've got miscompiles of mksh with gcc-13 on x32 with dietlibc.

I could reproduce this in a chroot by doing…

export CC='diet -Os gcc'
export CFLAGS='-g -Wformat -Werror=format-security -Wall -Wextra'
export CPPFLAGS='-Wdate-time -D_FORTIFY_SOURCE=2 -DMKSH_BUILDMEAT'
sh Build.sh -r -j
./mksh -c 'x=q; x=${ echo a; typeset e=2; return 3; echo x$e;}; echo .$x.'

… in an mksh source tree. (Output is “..” but “.a.” was expected.)

Adding -fno-builtin-strchr to CFLAGS makes the problem go away.

This is as far as I could reduce this; more would involve diving
into the gcc internals.


-- System Information:
Debian Release: trixie/sid
  APT prefers unreleased
  APT policy: (500, 'unreleased'), (500, 'unstable')
Architecture: x32 (x86_64)

Kernel: Linux 5.10.0-23-amd64 (SMP w/4 CPU threads)
Kernel taint flags: TAINT_FIRMWARE_WORKAROUND
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968) (ignored: LC_ALL set to C), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: unable to detect

Versions of packages gcc-13 depends on:
ii  binutils       2.41-4
ii  cpp-13         13.2.0-1
ii  gcc-13-base    13.2.0-1
ii  libc6          2.37-7
ii  libcc1-0       13.2.0-1
ii  libgcc-13-dev  13.2.0-1
ii  libgcc-s1      13.2.0-1
ii  libgmp10       2:6.3.0+dfsg-2
ii  libisl23       0.26-3
ii  libmpc3        1.3.1-1
ii  libmpfr6       4.2.0-1
ii  libstdc++6     13.2.0-1
ii  libzstd1       1.5.5+dfsg2-1
ii  zlib1g         1:1.2.13.dfsg-3

Versions of packages gcc-13 recommends:
ii  libc6-dev  2.37-7

Versions of packages gcc-13 suggests:
pn  gcc-13-doc       <none>
pn  gcc-13-locales   <none>
pn  gcc-13-multilib  <none>

-- no debconf information