armel test failure with clang-16: undefined reference to `__atomic_store_1'

[drew-parsons]

xtensor 0.24.7-1 tests fail on armel (gnueabi) architecture with clang 16.0.6.
The tests pass with g++ 13.2.0, and pass with clang-16 on other architectures.
A test log is found at https://ci.debian.net/data/autopkgtest/unstable/armel/x/xtensor/38202370/log.gz
see also https://ci.debian.net/packages/x/xtensor/unstable/armel/

Except of the test log is

520s [100%] Linking CXX executable test_xtensor_lib
520s /usr/bin/cmake -E cmake_link_script CMakeFiles/test_xtensor_lib.dir/link.txt --verbose=1
520s /usr/bin/clang++  -DXSIMD_ENABLE_XTL_COMPLEX=1 -std=c++14 -Wunused-parameter -Wextra -Wreorder -Wconversion -Wsign-conversion -Wold-style-cast -Wunused-variable -O3 -DNDEBUG -rdynamic CMakeFiles/test_xtensor_lib.dir/main.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xadaptor_semantic.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xarray_adaptor.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xarray.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xblockwise_reducer.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xbroadcast.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xbuilder.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xcontainer_semantic.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xeval.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xexception.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xexpression.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xexpression_traits.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xfunction.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xfunc_on_xexpression.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xmultiindex_iterator.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xiterator.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xmath.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xoperation.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xoptional_assembly.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xreducer.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xscalar.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xscalar_semantic.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xshape.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xstorage.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xstrided_view.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xstrides.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xtensor.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xtensor_adaptor.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xtensor_semantic.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xview.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xview_semantic.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xutils.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xsimd8.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xaccumulator.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xadapt.cpp.o CMakeFiles/test_xtensor_lib.dir/test_strided_assign.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xassign.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xaxis_iterator.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xaxis_slice_iterator.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xbuffer_adaptor.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xchunked_array.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xchunked_view.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xcomplex.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xcsv.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xdatesupport.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xdynamic_view.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xfunctor_adaptor.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xfixed.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xhistogram.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xpad.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xindex_view.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xio.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xlayout.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xmanipulation.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xmasked_view.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xmath_result_type.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xnan_functions.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xnoalias.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xnorm.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xoptional.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xoptional_assembly_adaptor.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xoptional_assembly_storage.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xset_operation.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xrandom.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xrepeat.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xsort.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xsimd.cpp.o CMakeFiles/test_xtensor_lib.dir/test_xvectorize.cpp.o CMakeFiles/test_xtensor_lib.dir/test_extended_xmath_interp.cpp.o CMakeFiles/test_xtensor_lib.dir/test_extended_broadcast_view.cpp.o CMakeFiles/test_xtensor_lib.dir/test_extended_xmath_reducers.cpp.o CMakeFiles/test_xtensor_lib.dir/test_extended_xhistogram.cpp.o CMakeFiles/test_xtensor_lib.dir/test_extended_xsort.cpp.o CMakeFiles/test_xtensor_lib.dir/test_sfinae.cpp.o -o test_xtensor_lib 
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o: in function `doctest::detail::Subcase::~Subcase()':
521s main.cpp:(.text+0x3f4c): undefined reference to `__atomic_load_1'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text+0x4034): undefined reference to `__atomic_store_1'
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o: in function `doctest::detail::ResultBuilder::log()':
521s main.cpp:(.text+0x5fe4): undefined reference to `__atomic_fetch_add_4'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text+0x6074): undefined reference to `__atomic_fetch_add_4'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text+0x6138): undefined reference to `__atomic_fetch_add_4'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text+0x616c): undefined reference to `__atomic_fetch_add_4'
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o: in function `doctest::detail::MessageBuilder::log()':
521s main.cpp:(.text+0x67e4): undefined reference to `__atomic_fetch_add_4'
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o:main.cpp:(.text+0x6828): more undefined references to `__atomic_fetch_add_4' follow
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o: in function `doctest::Context::run()':
521s main.cpp:(.text+0xa144): undefined reference to `__atomic_store_1'
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o: in function `std::atomic<bool>::operator=(bool)':
521s main.cpp:(.text._ZNSt6atomicIbEaSEb[_ZNSt6atomicIbEaSEb]+0xc): undefined reference to `__atomic_store_1'
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o: in function `doctest::detail::MultiLaneAtomic<int>::load(std::memory_order) const':
521s main.cpp:(.text._ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order[_ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order]+0xc): undefined reference to `__atomic_load_4'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text._ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order[_ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order]+0x1c): undefined reference to `__atomic_load_4'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text._ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order[_ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order]+0x2c): undefined reference to `__atomic_load_4'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text._ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order[_ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order]+0x3c): undefined reference to `__atomic_load_4'
521s /usr/bin/arm-linux-gnueabi-ld: main.cpp:(.text._ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order[_ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order]+0x4c): undefined reference to `__atomic_load_4'
521s /usr/bin/arm-linux-gnueabi-ld: CMakeFiles/test_xtensor_lib.dir/main.cpp.o:main.cpp:(.text._ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order[_ZNK7doctest6detail15MultiLaneAtomicIiE4loadESt12memory_order]+0x5c): more undefined references to `__atomic_load_4' follow
...

openssl once had problems with clang and atomic, cf. openssl/openssl#16572. So adding -latomic might help. But it's strange only one architecture is affected. Maybe it's a bug in clang. They've had such problems in the past but that should have been fixed already.

[drew-parsons]

Worth noting that xtensor 0.24.7-1 is passing tests on armel with debian testing, https://ci.debian.net/packages/x/xtensor/testing/armel/

Not clear what the pertinent difference is between the failing debian unstable environment and the passing debian testing environment. Both runs used clang 1:16.0.6-15, so the problem is not really clang.

[tdegeus]

Thanks for reporting.

I would say that it is likely a compiler (implementation) bug, as tests are fine elsewhere. Regardless, it is hard to investigate if we don't have a reproducer in the CI. So either we should have that, or you would have to investigate even further unfortunately

[drew-parsons]

You're probably right, it might be a compiler issue that xtensor can't fix. For what it's worth the problem with missing atomic symbols occasionally shows up in other packages (currently netgen, and on powerpc not just armel, and that's with g++ not clang)

In any case the xtensor tests did eventually pass on armel,
https://ci.debian.net/data/autopkgtest/unstable/armel/x/xtensor/39720598/log.gz
Not clear what changed, package versions seem to be the same.

So I'll close this issue now.