There was a problem compiling the FLANN CADA 9.2，How to fix ?

[Auroratan]

parameter of abstract class type "flann::KDTreeCuda3dIndex<flann::L1>" is not allowed: flann_cuda_s d:\pcl1.9.1\3rdparty\flann\source\flann-1.8.0-src\src\cpp\flann\algorithms\kdtree_cuda_3d_index.h 124
function returning abstract class "flann::KDTreeCuda3dIndex<flann::L1>" is not allowed: flann_cuda_s d:\pcl1.9.1\3rdparty\flann\source\flann-1.8.0-src\src\cpp\flann\algorithms\kdtree_cuda_3d_index.h 124

error points to the code :
KDTreeCuda3dIndex(const KDTreeCuda3dIndex& other);
KDTreeCuda3dIndex operator=(KDTreeCuda3dIndex other);

vs2017 indicates that the function definition was not found！how to fix?

problem:
d:\pcl1.9.1\3rdparty\flann\source\flann-1.8.0-src\src\cpp\flann\algorithms\kdtree_cuda_3d_index.h(228): warning : overloaded function "flann::NNIndex::knnSearch [with Distance=flann::L1]" is hidden by "flann::KDTreeCuda3dIndex::knnSearch [with Distance=flann::L1]" -- virtual function override intended?
2> detected during instantiation of class "flann::KDTreeCuda3dIndex [with Distance=flann::L1]"
2>D:/PCL1.9.1/3rdParty/Flann/source/flann-1.8.0-src/src/cpp/flann/algorithms/kdtree_cuda_3d_index.cu(838): here
2>
2>d:\pcl1.9.1\3rdparty\flann\source\flann-1.8.0-src\src\cpp\flann\algorithms\kdtree_cuda_3d_index.h(124): error : parameter of abstract class type "flann::KDTreeCuda3dIndex<flann::L1>" is not allowed:
2> pure virtual function "flann::NNIndex::findNeighbors [with Distance=flann::L1]" has no overrider
2> detected during instantiation of class "flann::KDTreeCuda3dIndex [with Distance=flann::L1]"
2>D:/PCL1.9.1/3rdParty/Flann/source/flann-1.8.0-src/src/cpp/flann/algorithms/kdtree_cuda_3d_index.cu(838): here
2>
2>d:\pcl1.9.1\3rdparty\flann\source\flann-1.8.0-src\src\cpp\flann\algorithms\kdtree_cuda_3d_index.h(124): error : function returning abstract class "flann::KDTreeCuda3dIndex<flann::L1>" is not allowed:
2> pure virtual function "flann::NNIndex::findNeighbors [with Distance=flann::L1]" has no overrider
2> detected during instantiation of class "flann::KDTreeCuda3dIndex [with Distance=flann::L1]"
2>D:/PCL1.9.1/3rdParty/Flann/source/flann-1.8.0-src/src/cpp/flann/algorithms/kdtree_cuda_3d_index.cu(838): here
2>