In example 01_basic_registration, it report an error which indicate eigen3 has unaligned arrays

[huiyan-dev]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Build the package
2. Run ./build/01_basic_registration

Additional context

3. Use gdb:
   (gdb) run
   Starting program: small_gicp/build/01_basic_registration
   [Thread debugging using libthread_db enabled]
   Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
   [New Thread 0x7ffff6446640 (LWP 52509)]
   [New Thread 0x7ffff5c45640 (LWP 52510)]
   [New Thread 0x7ffff5444640 (LWP 52511)]
   01_basic_registration: /usr/include/eigen3/Eigen/src/Core/DenseStorage.h:147: Eigen::internal::plain_array<T, Size, MatrixOrArrayOptions, 64>::plain_array() [with T = double; int Size = 16; int MatrixOrArrayOptions = 0]: Assertion (internal::UIntPtr(eigen_unaligned_array_assert_workaround_gcc47(array)) & (63)) == 0 && "this assertion is explained here: " "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html" " **** READ THIS WEB PAGE !!! ****"' failed. 01_basic_registration: /usr/include/eigen3/Eigen/src/Core/DenseStorage.h:147: Eigen::internal::plain_array<T, Size, MatrixOrArrayOptions, 64>::plain_array() [with T = double; int Size = 16; int MatrixOrArrayOptions = 0]: Assertion (internal::UIntPtr(eigen_unaligned_array_assert_workaround_gcc47(array)) & (63)) == 0 && "this assertion is explained here: " "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html" " **** READ THIS WEB PAGE !!! ****"' failed.
   01_basic_registration: /usr/include/eigen3/Eigen/src/Core/DenseStorage.h:147: Eigen::internal::plain_array<T, Size, MatrixOrArrayOptions, 64>::plain_array() [with T = double; int Size = 16; int MatrixOrArrayOptions = 0]: Assertion (internal::UIntPtr(eigen_unaligned_array_assert_workaround_gcc47(array)) & (63)) == 0 && "this assertion is explained here: " "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html" " **** READ THIS WEB PAGE !!! ****"' failed. 01_basic_registration: /usr/include/eigen3/Eigen/src/Core/DenseStorage.h:147: Eigen::internal::plain_array<T, Size, MatrixOrArrayOptions, 64>::plain_array() [with T = double; int Size = 16; int MatrixOrArrayOptions = 0]: Assertion (internal::UIntPtr(eigen_unaligned_array_assert_workaround_gcc47(array)) & (63)) == 0 && "this assertion is explained here: " "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html" " **** READ THIS WEB PAGE !!! ****"' failed.

Thread 4 "01_basic_regist" received signal SIGABRT, Aborted.
[Switching to Thread 0x7ffff5444640 (LWP 52511)]
__pthread_kill_implementation (no_tid=0, signo=6, threadid=140737308280384) at ./nptl/pthread_kill.c:44
44 ./nptl/pthread_kill.c: No such file or directory.
(gdb) bt
#0 __pthread_kill_implementation (no_tid=0, signo=6, threadid=140737308280384) at ./nptl/pthread_kill.c:44
#1 __pthread_kill_internal (signo=6, threadid=140737308280384) at ./nptl/pthread_kill.c:78
#2 __GI___pthread_kill (threadid=140737308280384, signo=signo@entry=6) at ./nptl/pthread_kill.c:89
#3 0x00007ffff7242476 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4 0x00007ffff72287f3 in __GI_abort () at ./stdlib/abort.c:79
#5 0x00007ffff722871b in __assert_fail_base (fmt=0x7ffff73dd130 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n",
assertion=0x55555556e670 "(internal::UIntPtr(eigen_unaligned_array_assert_workaround_gcc47(array)) & (63)) == 0 && "this assertion is explained here: " "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.htm"..., file=0x55555556e4b8 "/usr/include/eigen3/Eigen/src/Core/DenseStorage.h", line=147, function=) at ./assert/assert.c:94
#6 0x00007ffff7239e96 in __GI___assert_fail (
assertion=0x55555556e670 "(internal::UIntPtr(eigen_unaligned_array_assert_workaround_gcc47(array)) & (63)) == 0 && "this assertion is explained here: " "http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.htm"..., file=0x55555556e4b8 "/usr/include/eigen3/Eigen/src/Core/DenseStorage.h", line=147,
function=0x55555556e5e0 "Eigen::internal::plain_array<T, Size, MatrixOrArrayOptions, 64>::plain_array() [with T = double; int Size = 16; int MatrixOrArrayOptions = 0]") at ./assert/assert.c:103
#7 0x000055555556ad5a in Eigen::internal::plain_array<double, 16, 0, 64>::plain_array (this=0x7ffff5443b90) at /usr/include/eigen3/Eigen/src/Core/DenseStorage.h:147
#8 0x0000555555569fc2 in Eigen::DenseStorage<double, 16, 4, 4, 0>::DenseStorage (this=0x7ffff5443b90) at /usr/include/eigen3/Eigen/src/Core/DenseStorage.h:211
#9 0x00007ffff7d4f9a0 in Eigen::PlainObjectBase<Eigen::Matrix<double, 4, 4, 0, 4, 4> >::PlainObjectBase<Eigen::CwiseNullaryOp<Eigen::internal::scalar_constant_op, Eigen::Matrix<double, 4, 4, 0, 4, 4> > > (
this=0x7ffff5443b90, other=...) at /usr/include/eigen3/Eigen/src/Core/PlainObjectBase.h:590
--Type for more, q to quit, c to continue without paging--
#10 0x00007ffff7d475ea in Eigen::Matrix<double, 4, 4, 0, 4, 4>::Matrix<Eigen::CwiseNullaryOp<Eigen::internal::scalar_constant_op, Eigen::Matrix<double, 4, 4, 0, 4, 4> > > (this=0x7ffff5443b90, other=...)
at /usr/include/eigen3/Eigen/src/Core/Matrix.h:423
#11 0x00007ffff7d40ca2 in small_gicp::estimate_local_features<small_gicp::NormalCovarianceSetter<small_gicp::PointCloud>, small_gicp::PointCloud, small_gicp::KdTree<small_gicp::PointCloud, small_gicp::AxisAlignedProjection> > (cloud=..., kdtree=..., num_neighbors=10, point_index=4655) at small_gicp/include/small_gicp/util/normal_estimation.hpp:78
#12 0x00007ffff7de6c55 in _ZN10small_gicp27estimate_local_features_ompINS_22NormalCovarianceSetterINS_10PointCloudEEES2_NS_6KdTreeIS2_NS_21AxisAlignedProjectionEEEEEvRT0_RT1_ii._omp_fn.0(void) ()
at small_gicp/include/small_gicp/util/normal_estimation_omp.hpp:24
#13 0x00007ffff7f40c0e in ?? () from /lib/x86_64-linux-gnu/libgomp.so.1
#14 0x00007ffff7294ac3 in start_thread (arg=) at ./nptl/pthread_create.c:442
#15 0x00007ffff7326850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

Expected behavior
fix the bug

Environment (please complete the following information):

• OS: [Ubuntu]
• Version [22.04.5 LTS]
• Language [C++]

[themightyoarfish]

if you are using PCL, make sure pcl was built with the same flags as are used for small_gicp and your project (specifically -march=native). you can bring them into your project with add_definitions(${PCL_DEFINITIONS}). if that does not help, try setting BUILD_WITH_MARCH_NATIVE=OFF for small_gicp.