Closed sloretz closed 4 years ago
clalancette
commented
4 years ago If I remember properly, this has something to do with either ament or colcon automatically doing this for you. Can you confirm whether this works if you make the plain CMake package an ament package, or building it with colcon (or both), makes it work?
sloretz
commented
4 years ago Can you confirm whether this works if you make the plain CMake package an ament package, or building it with colcon (or both), makes it work?
I am building it with colcon.
If I add a package.xml then the build succeeds. Nothing else changed. It's still a plain CMake package and I'm building the same way using ROS Rolling deb packages.
<?xml version="1.0"?>
<package format="2">
<name>find_fastrtps_test</name>
<version>0.1.0</version>
<description>Debugging issues with FastRTPS CMake module.</description>
<maintainer email="sloretz@openrobotics.org">Shane Loretz</maintainer>
<license>Apache License 2.0</license>
<build_depend>rclcpp</build_depend>
<export>
<build_type>cmake</build_type>
</export>
</package>If I add a
package.xmlthen the build succeeds. Nothing else changed. It's still a plain CMake package and I'm building the same way using ROS Rolling deb packages.
Weird. I'm guessing that colcon is doing something differently there with regards to CMAKE_PREFIX_PATH when it finds a package.xml. But we are deep into speculation territory, so I'll stop guessing here.
sloretz
commented
4 years ago Weird. I'm guessing that colcon is doing something differently there with regards to CMAKE_PREFIX_PATH when it finds a package.xml. But we are deep into speculation territory, so I'll stop guessing here.
Very weird. With and without the package.xml all CMake variables are identical (edit: in the top-level CMakeLists.txt).
get_cmake_property(_variableNames VARIABLES)
list (SORT _variableNames)
foreach (_variableName ${_variableNames})
message(STATUS "${_variableName}=${${_variableName}}")
endforeach()That didn't include the path variables in the CMAKE_PREFIX_PATH documentation, but those are exactly the same too with and without a package.xml.
message(STATUS "CMAKE_SYSTEM_PREFIX_PATH=${CMAKE_SYSTEM_PREFIX_PATH}")
message(STATUS "CMAKE_INCLUDE_PATH=${CMAKE_INCLUDE_PATH}")
message(STATUS "CMAKE_LIBRARY_PATH=${CMAKE_LIBRARY_PATH}")
message(STATUS "CMAKE_PROGRAM_PATH=${CMAKE_PROGRAM_PATH}")
message(STATUS "CMAKE_PREFIX_PATH=${CMAKE_PREFIX_PATH}")
message(STATUS "CMAKE_IGNORE_PATH=${CMAKE_IGNORE_PATH}")-- CMAKE_SYSTEM_PREFIX_PATH=/usr/local;/usr;/;/usr;/home/sloretz/bigssd/drake_ros_demos/ws/install/find_fastrtps_test;/usr/X11R6;/usr/pkg;/opt
-- CMAKE_INCLUDE_PATH=
-- CMAKE_LIBRARY_PATH=
-- CMAKE_PROGRAM_PATH=
-- CMAKE_PREFIX_PATH=
-- CMAKE_IGNORE_PATH=I'm not sure what's different here, might have to read the find_library() docs for more clues.
sloretz
commented
4 years ago Regardless, if the Find module can find_package() the two projects, it should have enough info to find the libraries from them. Maybe the fastrtps-config.cmake and fastcdr-config.cmake are setting variables that can be put into HINTS to the find_library() calls?
sloretz
commented
4 years ago :tada: made a wrapper script to catch how CMake is invoked. The (first) cmake command is exactly the same with and without a package.xml
/usr/bin/cmake /home/sloretz/bigssd/drake_ros_demos/ws/src/find_fastrtps_test -DCMAKE_INSTALL_PREFIX=/home/sloretz/bigssd/drake_ros_demos/ws/install/find_fastrtps_testWhen I made the script echo environment variables it shows a single diff between two builds: CMAKE_PREFIX_PATH is set to /opt/ros/rolling. No idea why that only happens when this package has a package.xml. No idea why echoing the CMake variable CMAKE_PREFIX_PATH in CMake shows a blank value when the environment variable is set. No idea why colcon (nor which colcon extension) would only set the environment variable when the package has a package.xml.
declare -x CMAKE_PREFIX_PATH="/opt/ros/rolling"I think I understand what's going on here. I think colcon-ros identifies a ROS package because a package.xml is present. Even though the build type is plain cmake, the colcon-ros CmakeBuildTask modifies the environment with add_app_to_cpp which appends AMENT_PREFIX_PATH to CMAKE_PREFIX_PATH.
There's a few things I think should be different.
fastcdr and fastrtps, then it should be able to find the libraries without CMAKE_PREFIX_PATH being set. There's probably something that can be done with HINTS to fix that. (that should be enough to close this ticket)package.xml should be the same, except that colcon could use the package.xml to make more packages available to a plain CMake package if they're listed in it's package.xml. There shouldn't be any magic in having a package.xml beyond listing a package's build type and dependencies.AMENT_PREFIX_PATH should be appended to CMAKE_PREFIX_PATH at all, regardless of build type. IIUC packages using ament_cmake create setup scripts that can be sourced to set environment variables. ament_python packages have a hook for setting PYTHONPATH. There should be a similar hook for CMAKE_PREFIX_PATH set by any ament_cmake package. That is, sourcing /opt/ros/<distro>/setup.bash should set CMAKE_PREFIX_PATH. This would enable plain CMake packages to be built without using colcon+package.xml or manually setting CMAKE_PREFIX_PATH/-DCMAKE_PREFIX_PATH.clalancette
commented
4 years ago @sloretz Do you think https://github.com/ros2/rosidl_typesupport_fastrtps/pull/56 would solve this issue? It was committed at the end of October, but we haven't done a release of that package into Rolling since.
sloretz
commented
4 years ago Do you think #56 would solve this issue? It was committed at the end of October, but we haven't done a release of that package into Rolling since.
Gah. Yup that should fix it. https://github.com/ros2/ros2/issues/943 looks like exactly this issue.
Bug report
Required Info:
Steps to reproduce issue
Create a workspace with a plain CMake package
find_fastrtps_testBuild that package
Runing with
--trace-expandshows FastRTPS and FastCDR are found, but thefind_library()calls appear to have been unsuccessfulExpected behavior
I would expect the CMake module to successfully find FastRTPS.
Additional information
The libraries exist:
/opt/ros/rolling/setup.bashis sourced, but noCMAKE_PREFIX_PATHvariable is set. I thought it would have been set to/opt/ros/rolling.