Set AMENT_PREFIX_PATH to $ENV{AMENT_PREFIX_PATH) in xacro-extras.cmake

[seantfish]

I was having an issue where I have derivative_robot_description referencing xacro files from original_robot_description which refer to package://original_robot_description.

I am also using xacro-extras.cmake to generate urdf files on build from *.urdf.xacro files.

Upon building, I would encounter this error:

<class 'ament_index_python.packages.PackageNotFoundError'>: "package 'original_robot_description' not found, searching: ['/path/to/ws/build/derivative_robot_description/ament_cmake_index']" "package 'original_robot_description' not found, searching: ['/path/to/ws/build/derivative_robot_description/ament_cmake_index']"

Upon investigating the colcon build logs, I found that list(JOIN AMENT_PREFIX_PATH ":" AMENT_PREFIX_PATH_ENV) was not actually populating at all, and only PROJECT_BUILD_INDEX was doing anything in COMMAND ${CMAKE_COMMAND} -E env AMENT_PREFIX_PATH="${PROJECT_BUILD_INDEX}:${AMENT_PREFIX_PATH_ENV}" xacro -o ${abs_output} ${input} ${_XACRO_REMAP}.

This change sets AMENT_PREFIX_PATH to $ENV{AMENT_PREFIX_PATH} and fixes the build issue.

[rhaschke]

I am surprised that this solves your issue.
You set the cmake variable AMENT_PREFIX_PATH, but you don't pass that variable to the environment when running xacro in line 89.
I suggest to get rid of AMENT_PREFIX_PATH_ENV, which doesn't seem to be used (anymore?).

[seantfish]

I was under the impression that AMENT_PREFIX_PATH_ENV is a reformatted version of AMENT_PREFIX_PATH. Getting rid of AMENT_PREFIX_PATH_ENV seems to still solve the problem on my end. Thanks!