Bug#1089991: [armel] FTBFS with undefined reference to `__atomic_fetch_add_8' due to opentbb cmake not adding -latomic

[Johannes Schauer Marin Rodrigues]

Package: vcmi
Version: 1.5.2+dfsg-3
Severity: serious
Tags: ftbfs
Justification: fails to build from source (but built successfully in the past)
X-Debbugs-Cc: debian-arm at lists.debian.org
User: debian-arm at lists.debian.org
Usertags: armel
Control: block -1 by #1088922
Control: block #1089523 by -1

Hi,

vcmi FTBFS on armel:

/usr/bin/c++ -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 -Wdate-time -D_FORTIFY_SOURCE=2 -Wall -Wextra -Wpointer-arith -Wuninitialized -Wmismatched-tags -Wno-unused-parameter -Wno-switch -Wno-reorder -Wno-sign-compare -Wno-varargs -Wl,-z,relro -Wl,-z,now CMakeFiles/vcmiserver.dir/StdInc.cpp.o CMakeFiles/vcmiserver.dir/EntryPoint.cpp.o -o ../bin/vcmiserver  -Wl,-rpath,"\$ORIGIN::::::::::::::::::::::::" /usr/lib/arm-linux-gnueabi/libminizip.so ../bin/libvcmiservercommon.a ../bin/libvcmi.so /usr/lib/arm-linux-gnueabi/libz.so -ldl -lrt /usr/lib/arm-linux-gnueabi/libboost_filesystem.so.1.83.0 /usr/lib/arm-linux-gnueabi/libboost_program_options.so.1.83.0 /usr/lib/arm-linux-gnueabi/libboost_locale.so.1.83.0 /usr/lib/arm-linux-gnueabi/libboost_thread.so.1.83.0 /usr/lib/arm-linux-gnueabi/libboost_atomic.so.1.83.0 /usr/lib/arm-linux-gnueabi/libboost_chrono.so.1.83.0 /usr/lib/arm-linux-gnueabi/libboost_date_time.so.1.83.0 /usr/lib/arm-linux-gnueabi/libminizip.so
/usr/bin/ld: ../bin/libvcmi.so: undefined reference to `__atomic_fetch_add_8'
/usr/bin/ld: ../bin/libvcmi.so: undefined reference to `__atomic_load_8'
collect2: error: ld returned 1 exit status

The problem is a missing -latomic. Adding the -latomic to the vcmi build system
itself would be wrong because the flag is only required if vcmi uses
tbb::parallel_for.

This patch to vcmi fixes the issue:

https://sources.debian.org/src/vcmi/latest/debian/patches/fix-armel-atomics.patch/

But applying this patch to fix the issue would be wrong as that would be
papering over an issue with the cmake files that opentbb ships.

Thus, blocking this bug by #1088922.

Thanks!

cheers, josch