Fix uninitialized build warnings

[jmackay2]

This fixes a few uninitialized build warnings.

This was tested on Ubuntu 24.04, c++ version 13.3.0.

Some of the warnings that this attempts to fix:

pcl/recognition/src/ransac_based/obj_rec_ransac.cpp: In member function ‘int pcl::recognition::ObjRecRANSAC::groupHypotheses(std::__cxx11::list<pcl::recognition::HypothesisBase>&, int, pcl::recognition::RigidTransformSpace&, HypothesisOctree&) const’:
pcl/recognition/src/ransac_based/obj_rec_ransac.cpp:300:77: warning: ‘b’ may be used uninitialized [-Wmaybe-uninitialized]
  300 |   float enlr = scene_bounds_enlargement_factor_*std::max (std::max (b[1]-b[0], b[3]-b[2]), b[5]-b[4]);
      |                                                                          ~~~^
pcl/recognition/src/ransac_based/obj_rec_ransac.cpp:299:9: note: ‘b’ declared here
  299 |   float b[6]; scene_octree_.getBounds (b);

In file included from /usr/include/eigen3/Eigen/SVD:36,
                 from /usr/include/eigen3/Eigen/Geometry:13,
                 from pcl/common/include/pcl/point_cloud.h:46,
                 from pcl/io/include/pcl/io/pcd_io.h:44,
                 from pcl/tools/ndt3d.cpp:37:
In member function ‘Eigen::SVDBase<MatrixType>::Index Eigen::SVDBase<MatrixType>::rank() const [with Derived = Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> >]’,
    inlined from ‘void Eigen::SVDBase<MatrixType>::_solve_impl(const RhsType&, DstType&) const [with RhsType = Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> >; DstType = Eigen::Matrix<double, 6, 1>; Derived = Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> >]’ at /usr/include/eigen3/Eigen/src/SVD/SVDBase.h:314:22,
    inlined from ‘static void Eigen::internal::Assignment<DstXprType, Eigen::Solve<DecType, RhsType>, Eigen::internal::assign_op<Scalar, Scalar>, Eigen::internal::Dense2Dense>::run(DstXprType&, const SrcXprType&, const Eigen::internal::assign_op<Scalar, Scalar>&) [with DstXprType = Eigen::Matrix<double, 6, 1>; DecType = Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >; RhsType = Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> >; Scalar = double]’ at /usr/include/eigen3/Eigen/src/Core/Solve.h:147:26,
    inlined from ‘void Eigen::internal::call_assignment_no_alias(Dst&, const Src&, const Func&) [with Dst = Eigen::Matrix<double, 6, 1>; Src = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; Func = assign_op<double, double>]’ at /usr/include/eigen3/Eigen/src/Core/AssignEvaluator.h:890:49,
    inlined from ‘Derived& Eigen::PlainObjectBase<Derived>::_set_noalias(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; Derived = Eigen::Matrix<double, 6, 1>]’ at /usr/include/eigen3/Eigen/src/Core/PlainObjectBase.h:797:41,
    inlined from ‘Eigen::PlainObjectBase<Derived>::PlainObjectBase(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; Derived = Eigen::Matrix<double, 6, 1>]’ at /usr/include/eigen3/Eigen/src/Core/PlainObjectBase.h:594:19,
    inlined from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const Eigen::EigenBase<OtherDerived>&) [with OtherDerived = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; _Scalar = double; int _Rows = 6; int _Cols = 1; int _Options = 0; int _MaxRows = 6; int _MaxCols = 1]’ at /usr/include/eigen3/Eigen/src/Core/Matrix.h:423:29,
    inlined from ‘void pcl::NormalDistributionsTransform<PointSource, PointTarget, Scalar>::computeTransformation(PointCloudSource&, const Matrix4&) [with PointSource = pcl::PointXYZ; PointTarget = pcl::PointXYZ; Scalar = float]’ at pcl/registration/include/pcl/registration/impl/ndt.hpp:125:33:
/usr/include/eigen3/Eigen/src/SVD/SVDBase.h:154:15: warning: ‘sv.Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6, 0, 6, 6>, 2>::<unnamed>.Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >::m_nonzeroSingularValues’ may be used uninitialized [-Wmaybe-uninitialized]
  154 |     Index i = m_nonzeroSingularValues-1;
      |               ^~~~~~~~~~~~~~~~~~~~~~~
In file included from pcl/registration/include/pcl/registration/ndt.h:638,
                 from pcl/tools/ndt3d.cpp:39:
pcl/registration/include/pcl/registration/impl/ndt.hpp: In member function ‘void pcl::NormalDistributionsTransform<PointSource, PointTarget, Scalar>::computeTransformation(PointCloudSource&, const Matrix4&) [with PointSource = pcl::PointXYZ; PointTarget = pcl::PointXYZ; Scalar = float]’:
pcl/registration/include/pcl/registration/impl/ndt.hpp:122:51: note: ‘sv’ declared here
  122 |     Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6>> sv(
      |                                                   ^~
In member function ‘Eigen::SVDBase<MatrixType>::Index Eigen::SVDBase<MatrixType>::rank() const [with Derived = Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> >]’,
    inlined from ‘void Eigen::SVDBase<MatrixType>::_solve_impl(const RhsType&, DstType&) const [with RhsType = Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> >; DstType = Eigen::Matrix<double, 6, 1>; Derived = Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> >]’ at /usr/include/eigen3/Eigen/src/SVD/SVDBase.h:314:22,
    inlined from ‘static void Eigen::internal::Assignment<DstXprType, Eigen::Solve<DecType, RhsType>, Eigen::internal::assign_op<Scalar, Scalar>, Eigen::internal::Dense2Dense>::run(DstXprType&, const SrcXprType&, const Eigen::internal::assign_op<Scalar, Scalar>&) [with DstXprType = Eigen::Matrix<double, 6, 1>; DecType = Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >; RhsType = Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> >; Scalar = double]’ at /usr/include/eigen3/Eigen/src/Core/Solve.h:147:26,
    inlined from ‘void Eigen::internal::call_assignment_no_alias(Dst&, const Src&, const Func&) [with Dst = Eigen::Matrix<double, 6, 1>; Src = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; Func = assign_op<double, double>]’ at /usr/include/eigen3/Eigen/src/Core/AssignEvaluator.h:890:49,
    inlined from ‘Derived& Eigen::PlainObjectBase<Derived>::_set_noalias(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; Derived = Eigen::Matrix<double, 6, 1>]’ at /usr/include/eigen3/Eigen/src/Core/PlainObjectBase.h:797:41,
    inlined from ‘Eigen::PlainObjectBase<Derived>::PlainObjectBase(const Eigen::DenseBase<OtherDerived>&) [with OtherDerived = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; Derived = Eigen::Matrix<double, 6, 1>]’ at /usr/include/eigen3/Eigen/src/Core/PlainObjectBase.h:594:19,
    inlined from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const Eigen::EigenBase<OtherDerived>&) [with OtherDerived = Eigen::Solve<Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6> > >, Eigen::CwiseUnaryOp<Eigen::internal::scalar_opposite_op<double>, const Eigen::Matrix<double, 6, 1> > >; _Scalar = double; int _Rows = 6; int _Cols = 1; int _Options = 0; int _MaxRows = 6; int _MaxCols = 1]’ at /usr/include/eigen3/Eigen/src/Core/Matrix.h:423:29,
    inlined from ‘void pcl::NormalDistributionsTransform<PointSource, PointTarget, Scalar>::computeTransformation(PointCloudSource&, const Matrix4&) [with PointSource = pcl::PointXYZ; PointTarget = pcl::PointXYZ; Scalar = float]’ at pcl/registration/include/pcl/registration/impl/ndt.hpp:125:33:
/usr/include/eigen3/Eigen/src/SVD/SVDBase.h:153:93: warning: ‘*(const Eigen::PlainObjectBase<Eigen::Matrix<double, 6, 1, 0, 6, 1> >::Scalar*)((char*)&sv + offsetof(Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6, 0, 6, 6>, 2>,Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6, 0, 6, 6>, 2>::<unnamed>.Eigen::SVDBase<Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6, 0, 6, 6>, 2> >::m_singularValues.Eigen::Matrix<double, 6, 1, 0, 6, 1>::<unnamed>.Eigen::PlainObjectBase<Eigen::Matrix<double, 6, 1, 0, 6, 1> >::<unnamed>.Eigen::MatrixBase<Eigen::Matrix<double, 6, 1, 0, 6, 1> >::<unnamed>.Eigen::DenseBase<Eigen::Matrix<double, 6, 1, 0, 6, 1> >::<unnamed>.Eigen::DenseCoeffsBase<Eigen::Matrix<double, 6, 1, 0, 6, 1>, 3>::<unnamed>.Eigen::DenseCoeffsBase<Eigen::Matrix<double, 6, 1, 0, 6, 1>, 1>::<unnamed>.Eigen::DenseCoeffsBase<Eigen::Matrix<double, 6, 1, 0, 6, 1>, 0>::<unnamed>))’ may be used uninitialized [-Wmaybe-uninitialized]
  153 |     RealScalar premultiplied_threshold = numext::maxi<RealScalar>(m_singularValues.coeff(0) * threshold(), (std::numeric_limits<RealScalar>::min)());
      |                                                                   ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
pcl/registration/include/pcl/registration/impl/ndt.hpp: In member function ‘void pcl::NormalDistributionsTransform<PointSource, PointTarget, Scalar>::computeTransformation(PointCloudSource&, const Matrix4&) [with PointSource = pcl::PointXYZ; PointTarget = pcl::PointXYZ; Scalar = float]’:
pcl/registration/include/pcl/registration/impl/ndt.hpp:122:51: note: ‘sv’ declared here
  122 |     Eigen::JacobiSVD<Eigen::Matrix<double, 6, 6>> sv(
      |                                                   ^~

In file included from pcl/common/include/pcl/memory.h:46,
                 from pcl/io/include/pcl/io/pcd_io.h:42,
                 from pcl/tools/obj2pcd.cpp:40:
In function ‘void pcl::setFieldValue(PointT&, std::size_t, const ValT&) [with PointT = PointNormal; ValT = float]’,
    inlined from ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointNormal]’ at pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:127:41:
pcl/common/include/pcl/type_traits.h:240:40: warning: ‘normal’ may be used uninitialized [-Wmaybe-uninitialized]
  240 |     *reinterpret_cast<ValT*>(data_ptr) = value;
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In file included from pcl/io/include/pcl/io/vtk_lib_io.h:260,
                 from pcl/tools/obj2pcd.cpp:41:
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp: In function ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointNormal]’:
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:125:13: note: ‘normal’ declared here
  125 |       float normal[3];
      |             ^~~~~~
In function ‘void pcl::setFieldValue(PointT&, std::size_t, const ValT&) [with PointT = PointXYZ; ValT = float]’,
    inlined from ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointXYZ]’ at pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:127:41:
pcl/common/include/pcl/type_traits.h:240:40: warning: ‘normal’ may be used uninitialized [-Wmaybe-uninitialized]
  240 |     *reinterpret_cast<ValT*>(data_ptr) = value;
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp: In function ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointXYZ]’:
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:125:13: note: ‘normal’ declared here
  125 |       float normal[3];
      |             ^~~~~~
[ 38%] Linking CXX executable ../bin/pcl_obj2pcd
[ 38%] Built target pcl_obj2pcd
[ 38%] Building CXX object tools/CMakeFiles/pcl_compute_hausdorff.dir/compute_hausdorff.cpp.o
In file included from pcl/common/include/pcl/memory.h:46,
                 from pcl/io/include/pcl/io/pcd_io.h:42,
                 from pcl/tools/vtk2pcd.cpp:40:
In function ‘void pcl::setFieldValue(PointT&, std::size_t, const ValT&) [with PointT = PointNormal; ValT = float]’,
    inlined from ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointNormal]’ at pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:127:41:
pcl/common/include/pcl/type_traits.h:240:40: warning: ‘normal’ may be used uninitialized [-Wmaybe-uninitialized]
  240 |     *reinterpret_cast<ValT*>(data_ptr) = value;
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In file included from pcl/io/include/pcl/io/vtk_lib_io.h:260,
                 from pcl/tools/vtk2pcd.cpp:41:
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp: In function ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointNormal]’:
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:125:13: note: ‘normal’ declared here
  125 |       float normal[3];
      |             ^~~~~~
In function ‘void pcl::setFieldValue(PointT&, std::size_t, const ValT&) [with PointT = PointXYZ; ValT = float]’,
    inlined from ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointXYZ]’ at pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:127:41:
pcl/common/include/pcl/type_traits.h:240:40: warning: ‘normal’ may be used uninitialized [-Wmaybe-uninitialized]
  240 |     *reinterpret_cast<ValT*>(data_ptr) = value;
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp: In function ‘void pcl::io::vtkPolyDataToPointCloud(vtkPolyData*, pcl::PointCloud<PointT>&) [with PointT = pcl::PointXYZ]’:
pcl/io/include/pcl/io/impl/vtk_lib_io.hpp:125:13: note: ‘normal’ declared here
  125 |       float normal[3];
      |             ^~~~~~

[mvieth]

Thanks for the pull request. Which compiler do you use when you see the warnings? Could you post the full warning messages? Do you know why the warnings occur? In the first two files, initializing with zeros seems more like silencing the warnings instead of an actual fix. In ndt.hpp, printing an error could make sense (something like PCL_ERROR("[%s::computeTransformation] JacobiSVD on hessian failed!\n", getClassName().c_str());). I am assuming sv.info() was introduced in Eigen 3.4.0?

[jmackay2]

Thanks for the pull request. Which compiler do you use when you see the warnings? Could you post the full warning messages? Do you know why the warnings occur? In the first two files, initializing with zeros seems more like silencing the warnings instead of an actual fix. In ndt.hpp, printing an error could make sense (something like PCL_ERROR("[%s::computeTransformation] JacobiSVD on hessian failed!\n", getClassName().c_str());). I am assuming sv.info() was introduced in Eigen 3.4.0?

I updated the PR info with better details with the full warning messages.

The warnings are all related to how the variables may be uninitialized. I guess the compiler can't determine that float normal[3] is actually initialized in normals->getTupleValue(i, normal). I believe the same is true for float b[6];.

Yes, sv.info() was a Eigen 3.4.0 update. I'm not terribly thrilled about having to wrap the svd check in the eigen version check, but it is nice that the new version tells you if SVD failed. I added a PCL_ERROR message in the svd check.

[mvieth]

I updated the PR info with better details with the full warning messages.

Thanks!

I looked a bit more into the warnings and the code and it really seems like they are false positives because the compiler is not "smart enough" (at least the ones in io and recognition). g++14 does not show the warnings any more. With that in mind, the changes look good to me. Thanks!