PotreeConverter: MacOS Sierra: fatal error: 'experimental/filesystem' file not found

Works with gcc-6 as well:

brew install gcc@6 cd /ABSOLUTE/PATH/TO/PotreeConverter/build cmake -DCMAKE_BUILD_TYPE=Release -DLASZIP_INCLUDE_DIRS=/ABSOLUTE/PATH/TO/LASlib/LASzip/dll/ -DLASZIP_LIBRARY=/ABSOLUTE/PATH/TO/LASlib/LASzip/build/src/liblaszip.dylib -DCMAKE_C_COMPILER=/usr/local/Cellar/gcc\@6/6.4.0_1/bin/gcc-6 -DCMAKE_CXX_COMPILER=/usr/local/Cellar/gcc\@6/6.4.0_1/bin/g++-6 ..

I can confirm that I was able to work around this issue on High Sierra 10.13.1, using (homebrew) gcc 7.2.0 and g++ 7.20.

The extra steps were (as mentioned in linked stackoverflow posts here) to update the PATH in .profile with:
export PATH=/usr/local/Cellar/gcc/7.2.0/bin:$PATH
export LC_ALL=C; unset LANGUAGE

It was also necessary to symlink the homebrew-syntax ‘gcc-7’ and ‘g+±7’ in /usr/local/Cellar/gcc/7.2.0/bin to ‘gcc’ and ‘g++’

When running the PotreeConverter cmake script, it is necessary to add the DCMAKE_C_COMPILER and DCMAKE_CXX_COMPILER flags. My cmake script ended up looking like this:

cmake -DCMAKE_C_COMPILER=/usr/local/Cellar/gcc/7.2.0/bin/gcc -DCMAKE_CXX_COMPILER=/usr/local/Cellar/gcc/7.2.0/bin/g++ -DCMAKE_BUILD_TYPE=Release -DLASZIP_INCLUDE_DIRS=/Users/automator/Documents/dev/workspaces/lastools/master/LASzip/dll -DLASZIP_LIBRARY=/Users/automator/Documents/dev/workspaces/lastools/master/LASzip/build/src/liblaszip.dylib ..

I can confirm a similar (possibly same) issue on GNU/Linux (Manjaro). After building lastools, I receive the following error on the make step when building PotreeConverter as described in the README. Here is the error:

$ make [ 8%] Building CXX object PotreeConverter/CMakeFiles/PotreeConverter.dir/src/PotreeConverter.cpp.o In file included from /home/matt/dev/workspaces/PotreeConverter/master/PotreeConverter/src/PotreeConverter.cpp:14:0: /home/matt/dev/workspaces/PotreeConverter/master/PotreeConverter/include/PotreeWriter.h:78:21: error: ‘std::function’ has not been declared void traverse(std::function<void(PWNode*)> callback); ^~~~~~~~ /home/matt/dev/workspaces/PotreeConverter/master/PotreeConverter/include/PotreeWriter.h:78:29: error: expected ‘,’ or ‘...’ before ‘<’ token void traverse(std::function<void(PWNode*)> callback); ^ /home/matt/dev/workspaces/PotreeConverter/master/PotreeConverter/include/PotreeWriter.h:80:33: error: ‘std::function’ has not been declared void traverseBreadthFirst(std::function<void(PWNode*)> callback); ^~~~~~~~ /home/matt/dev/workspaces/PotreeConverter/master/PotreeConverter/include/PotreeWriter.h:80:41: error: expected ‘,’ or ‘...’ before ‘<’ token void traverseBreadthFirst(std::function<void(PWNode*)> callback); ^ /home/matt/dev/workspaces/PotreeConverter/master/PotreeConverter/src/PotreeConverter.cpp: In function ‘void Potree::writeSources(std::__cxx11::string, std::vector<std::__cxx11::basic_string<char> >, std::vector<int>, std::vector<Potree::AABB>, std::__cxx11::string)’: /home/matt/dev/workspaces/PotreeConverter/master/PotreeConverter/src/PotreeConverter.cpp:260:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < sourceFilenames.size(); i++){ ~~^~~~~~~~~~~~~~~~~~~~~~~~ make[2]: *** [PotreeConverter/CMakeFiles/PotreeConverter.dir/build.make:207: PotreeConverter/CMakeFiles/PotreeConverter.dir/src/PotreeConverter.cpp.o] Error 1 make[1]: *** [CMakeFiles/Makefile2:86: PotreeConverter/CMakeFiles/PotreeConverter.dir/all] Error 2 make: *** [Makefile:130: all] Error 2

Just researching this issue: experimental/filesystem is part of gcc since gcc 5.3: https://isocpp.org/files/papers/P0218r1.html and the version of gcc usually available on mac is 4.2.1. For a mac build we would need to replace all experimental/filesystem code with a different, cross platform, implementation. Any help or PR in that direction is welcome (though I am researching this atm. I will post any progress)

Could it be that /dev/workspaces/lastools/master/LASzip/dll and ~/dev/workspaces/lastools/master/LASzip/build/src/liblaszip.so are no longer compatible with PotreeConverter? Since the master branch of lastools may have changed?