lightdm-1.9.15 fails to build with clang-3.4

[Jauhien Piatlicki]

Subj, build log on Gentoo GNU/Linux attached.

[Austin English (austinenglish)]

Created attachment 371304
emerge log

clang -fno-color-diagnostics -DHAVE_CONFIG_H -I. -I../.. -Wall -Wstrict-prototypes -Wnested-externs -Werror=missing-prototypes -Werror=implicit-function-declaration -Werror=pointer-arith -Werror=init-self -Werror=format-security -Werror=format=2 -Werror=missing-include-dirs -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -pthread -I/usr/include/gio-unix-2.0/ -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -O2 -march=corei7 -g -pipe -c -o initctl-status.o `test -f 'status.c' || echo './'`status.c
status.c:87:30: error: format string is not a string literal
      [-Werror,-Wformat-nonliteral]
    vsnprintf (status, 1024, format, ap);
                             ^~~~~~
1 error generated.
Makefile:1232: recipe for target 'initctl-status.o' failed

Reproducible: Always

Steps to Reproduce:
set CC=clang (see https://wiki.gentoo.org/wiki/Clang)
emerge -v =x11-misc/lightdm-1.8.5-r1
Actual Results:
emerge fails

Expected Results:
emerge succeeds

dev-light-2014013002 ~ # emerge --info
Portage 2.2.8-r1 (default/linux/amd64/13.0, gcc-4.8.2, glibc-2.18-r1, 3.12.0-gentoo-devlight-1 x86_64)
=================================================================
System uname: Linux-3.12.0-gentoo-devlight-1-x86_64-Intel-R-_Core-TM-_i7_CPU_960_@_3.20GHz-with-gentoo-2.2
KiB Mem: 6106996 total, 1437380 free
KiB Swap: 11718652 total, 11355728 free
Timestamp of tree: Thu, 30 Jan 2014 20:00:01 +0000
ld GNU ld (GNU Binutils) 2.24
app-shells/bash: 4.2_p45-r1
dev-java/java-config: 2.2.0
dev-lang/python: 2.7.6, 3.3.3
dev-util/cmake: 2.8.12.2
dev-util/pkgconfig: 0.28
sys-apps/baselayout: 2.2
sys-apps/openrc: 0.12.4
sys-apps/sandbox: 2.6-r1
sys-devel/autoconf: 2.13, 2.69
sys-devel/automake: 1.11.6, 1.12.6, 1.13.4, 1.14.1
sys-devel/binutils: 2.24-r2
sys-devel/gcc: 4.8.2
sys-devel/gcc-config: 1.8
sys-devel/libtool: 2.4.2
sys-devel/make: 4.0-r1
sys-kernel/linux-headers: 3.13 (virtual/os-headers)
sys-libs/glibc: 2.18-r1
Repositories: gentoo
ACCEPT_KEYWORDS="amd64 ~amd64"
ACCEPT_LICENSE="*"
CBUILD="x86_64-pc-linux-gnu"
CFLAGS="-O2 -march=corei7 -g -pipe"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/share/gnupg/qualified.txt"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo"
CXXFLAGS="-O2 -march=corei7 -g -pipe"
DISTDIR="/var/portage/distfiles"
FCFLAGS="-O2 -pipe"
FEATURES="assume-digests binpkg-logs buildpkg config-protect-if-modified distlocks ebuild-locks fixlafiles merge-sync news parallel-fetch preserve-libs protect-owned sandbox sfperms splitdebug strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr"
FFLAGS="-O2 -pipe"
GENTOO_MIRRORS="http://distfiles.gentoo.org"
INSTALL_MASK="/usr/lib/systemd/system /lib/systemd"
LANG="en_US.utf8"
LDFLAGS="-Wl,-O1 -Wl,--as-needed"
MAKEOPT...

[Jauhien Piatlicki (piatlicki)]

The same for =x11-misc/lightdm-1.9.15 and =sys-devel/clang-3.4-r100

[Jauhien Piatlicki (piatlicki)]

See also: https://bugs.gentoo.org/show_bug.cgi?id=502480

[Robert Ancell (robert-ancell)]

The problem is in logger.c:

void
logger_logv_default (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap)
{
    ...
    tmp = g_vsnprintf (NULL, 0, format, ap_copy);
    ...
}

So clang doesn't know that "format" is a valid format string. To mark this in GCC we can use:
__attribute__ ((format_arg (3)))

clang supports format (printf, a, b) but not format_arg. So not sure how we mark this correctly...

[Jauhien Piatlicki (piatlicki)]

Upstream was informed: https://bugs.launchpad.net/lightdm/+bug/1310257

Please, somebody add this link to see also, as I do not have permissions to do it.

[D-rammelt (d-rammelt)]

lightdm-1.11.9 compiles with Clang. Tested on clang/llvm 3.5.0.

[D-rammelt (d-rammelt)]

Created attachment 384740
Fix logger.c compiling with Clang

diff -aur ./lightdm-1.8.5/src/logger.c ./lightdm-1.11.9/src/logger.c

[D-rammelt (d-rammelt)]

Created attachment 384770
disable tests

Tests must also be disabled in the ebuild as per 1.11.9

[Jauhien (jauhien)]

=x11-misc/lightdm-1.9.0 works for me also. This bug should be closed, when it will be unmasked.

[Jauhien (jauhien)]

1.11.9 I mean, wrong copy/paste

[Jauhien (jauhien)]

Please, close this bug as =x11-misc/lightdm-1.11.9 is unmasked already.

[Austin English (austinenglish)]

Closing.