MacOS: Build Error: no member named 'filesystem' in namespace 'boost'

[farhanhubble]

I'm following the steps given for MacOS and ran into a compilation error on the make step.

[ 25%] Building CXX object CMakeFiles/environment.dir/src/environment.cpp.o
In file included from /Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/environment.cpp:7:
/Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/processPointClouds.h:47:17: error: no member named 'filesystem' in namespace 'boost'; did you mean 'std::__fs::filesystem'?
    std::vector<boost::filesystem::path> streamPcd(std::string dataPath);
                ^~~~~~~~~~~~~~~~~
                std::__fs::filesystem
/Library/Developer/CommandLineTools/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__filesystem/u8path.h:32:1: note: 'std::__fs::filesystem' declared here
_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
^
/Library/Developer/CommandLineTools/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__config:724:62: note: expanded from macro '_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM'
      _LIBCPP_BEGIN_NAMESPACE_STD namespace __fs { namespace filesystem {
                                                             ^
In file included from /Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/environment.cpp:9:
/Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/processPointClouds.cpp:132:13: error: no member named 'filesystem' in namespace 'boost'; did you mean 'std::__fs::filesystem'?
std::vector<boost::filesystem::path> ProcessPointClouds<PointT>::streamPcd(std::string dataPath)
            ^~~~~~~~~~~~~~~~~
            std::__fs::filesystem
/Library/Developer/CommandLineTools/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__filesystem/u8path.h:32:1: note: 'std::__fs::filesystem' declared here
_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
^
/Library/Developer/CommandLineTools/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__config:724:62: note: expanded from macro '_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM'
      _LIBCPP_BEGIN_NAMESPACE_STD namespace __fs { namespace filesystem {
                                                             ^
In file included from /Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/environment.cpp:9:
/Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/processPointClouds.cpp:135:17: error: no member named 'filesystem' in namespace 'boost'; did you mean 'std::__fs::filesystem'?
    std::vector<boost::filesystem::path> paths(boost::filesystem::directory_iterator{dataPath}, boost::filesystem::directory_iterator{});
                ^~~~~~~~~~~~~~~~~
                std::__fs::filesystem
/Library/Developer/CommandLineTools/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__filesystem/u8path.h:32:1: note: 'std::__fs::filesystem' declared here
_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM
^
/Library/Developer/CommandLineTools/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__config:724:62: note: expanded from macro '_LIBCPP_BEGIN_NAMESPACE_FILESYSTEM'
      _LIBCPP_BEGIN_NAMESPACE_STD namespace __fs { namespace filesystem {
                                                             ^
In file included from /Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/environment.cpp:9:
/Users/farhan/devel/udacity/SFND_Lidar_Obstacle_Detection/src/processPointClouds.cpp:135:48: error: no member named 'filesystem' in namespace 'boost'; did you mean 'std::__fs::filesystem'?
    std::vector<boost::filesystem::path> paths(boost::filesystem::directory_iterator{dataPath}, boost::filesystem::directory_iterator{});
                                               ^~~~~~~~~~~~~~~~~
                                               std::__fs::filesystem
/Library/Developer/CommandLineTools/SDKs/MacOSX14.2.sdk/usr/include/c++/v1/__filesystem/u8path.h:32:1: note: 'std::__fs::filesystem' declared here

[farhanhubble]

System information

MacOS Sonoma on Intel Silicon 

boost: stable 1.84.0 (bottled), HEAD
Collection of portable C++ source libraries
https://www.boost.org/
/usr/local/Cellar/boost/1.84.0 (16,054 files, 500.8MB) *
  Poured from bottle using the formulae.brew.sh API on 2024-02-20 at 22:42:08
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/b/boost.rb
License: BSL-1.0
==> Dependencies
Required: icu4c ✔, xz ✔, zstd ✔

gcc: stable 13.2.0 (bottled), HEAD
GNU compiler collection
https://gcc.gnu.org/
/usr/local/Cellar/gcc/13.2.0 (1,590 files, 401.9MB) *
  Poured from bottle using the formulae.brew.sh API on 2024-02-20 at 22:42:25
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/g/gcc.rb
License: GPL-3.0-or-later with GCC-exception-3.1
==> Dependencies
Required: gmp ✔, isl ✔, libmpc ✔, mpfr ✔, zstd ✔

pcl: stable 1.14.0 (bottled), HEAD
Library for 2D/3D image and point cloud processing
https://pointclouds.org/
/usr/local/Cellar/pcl/1.14.0_1 (1,254 files, 146.7MB) *
  Poured from bottle using the formulae.brew.sh API on 2024-02-20 at 22:45:47
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/p/pcl.rb
License: BSD-3-Clause
==> Dependencies
Build: cmake ✔, pkg-config ✘
Required: boost ✔, cminpack ✔, eigen ✔, flann ✔, glew ✔, libpcap ✔, libusb ✔, qhull ✔, qt ✔, vtk ✔, libomp ✔

[farhanhubble]

Triage: The file SFND_Lidar_Obstacle_Detection/src/processPointClouds.h does not include boost/filesystem headers nor is there anything in the CmakeList.txt file. The could have been "accidentally working" due to another package, likely QT, importing boost headers in its previous versions.

[farhanhubble]

Adding an explicit #include <boost/filesystem.hpp> to processPointClouds.h solves the issue.