error: identifier "nullptr" is undefined

Your Environment

• Operating System and version: Ubuntu 16.04
• Compiler: GCC 5.4.0
• PCL Version: 1.9.1

problem -- make process failed

[ 97%] Building NVCC (Device) object gpu/octree/CMakeFiles/pcl_gpu_octree.dir/src/cuda/pcl_gpu_octree_generated_octree_builder.cu.o
/home/zhaopf/pcl/gpu/octree/include/pcl/gpu/octree/device_format.hpp(81): warning: list initialization syntax is a C++11 feature
/home/zhaopf/pcl/gpu/octree/src/internal.hpp(59): error: identifier "nullptr" is undefined
1 error detected in the compilation of "/tmp/tmpxft_00000fae_00000000-13_octree_builder.compute_70.cpp1.ii".
CMake Error at pcl_gpu_octree_generated_octree_builder.cu.o.cmake:268 (message):
Error generating file
/home/zhaopf/pcl/release/gpu/octree/CMakeFiles/pcl_gpu_octree.dir/src/cuda/./pcl_gpu_octree_generated_octree_builder.cu.o
gpu/octree/CMakeFiles/pcl_gpu_octree.dir/build.make:2309: recipe for target 'gpu/octree/CMakeFiles/pcl_gpu_octree.dir/src/cuda/pcl_gpu_octree_generated_octree_builder.cu.o' failed
make[2]: *** [gpu/octree/CMakeFiles/pcl_gpu_octree.dir/src/cuda/pcl_gpu_octree_generated_octree_builder.cu.o] Error 1
CMakeFiles/Makefile2:8367: recipe for target 'gpu/octree/CMakeFiles/pcl_gpu_octree.dir/all' failed
make[1]: *** [gpu/octree/CMakeFiles/pcl_gpu_octree.dir/all] Error 2
Makefile:160: recipe for target 'all' failed
make: *** [all] Error 2

##HELP!
Does anyone encounter this problem like me? Please help me out~

Start by reproducing the GPU octree build with Ubuntu 16.04, GCC 5.4.0, and PCL 1.9.1, then inspect gpu/octree/src/internal.hpp and gpu/octree/include/pcl/gpu/octree/device_format.hpp around the reported lines. Done means the CUDA compilation completes without the nullptr error and the GPU octree target builds successfully.