macOS, roslib: No definition of [libboost-filesystem-dev] for OS [osx]

edit

I’m trying to install on macOS as per the macOS guide in the ROS wiki. So far so good up until section 2.5.1 when running the command

rosdep install --from-paths src --ignore-src --rosdistro melodic -y --skip-keys google-mock

which ends with the errors:

ERROR: the following packages/stacks could not have their rosdep keys resolved
to system dependencies:
roslib: No definition of [libboost-filesystem-dev] for OS [osx]
rosbag: No definition of [python-gnupg] for OS [osx]
rosbag_storage: No definition of [libgpgme-dev] for OS [osx]

Seems that I’m missing some dependencies. I'm not sure if I need these dependencies. The only things I want to run are rostopic and rosbag commands.

The guide says

Note: After running rosdep you will see the error below, so you may encounter issues when running roslisp or rosbag. (would be great if someone can test).

referring to the python-gnupg and libgpgme-dev dependencies.

I’m new to ROS. Any tips would be greatly appreciated.

EDIT: Ah, the next command

./src/catkin/bin/catkin_make_isolated --install -DCMAKE_BUILD_TYPE=Release -DCMAKE_MACOSX_RPATH=ON -DCMAKE_INSTALL_RPATH=$HOME/ros_catkin_ws/install_isolated/lib

failed with

CMake Error at /usr/local/Cellar/cmake/3.15.1/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find Boost (missing: Boost_INCLUDE_DIR thread system)

I suppose I do need boost. I should add this to the wiki page.