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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Jazzy Interface generation","articleBody":"I have been maintaining a (desktop) version of this repo for humble (https://github.com/EGAlberts/ros2_java) particularly the version I use most is .\n\nI recently attempted to update to Jazzy to access newer versions of libraries related to my work, however I discovered there is an issue with  CMake builds when it comes to Jazzy. I tried to isolate it to very simple builds such as just generating the java versions of builtin_interfaces.\n\nI get errors along these lines:\nCMake Error at /opt/ros/jazzy/share/rosidl_generator_c/cmake/rosidl_generator_c_generate_interfaces.cmake:145 (add_library):\n  add_library cannot create ALIAS target\n  \"builtin_interfaces::builtin_interfaces__rosidl_generator_c\" because\n  another target with the same name already exists.\nCall Stack (most recent call first):\n  /opt/ros/jazzy/share/ament_cmake_core/cmake/core/ament_execute_extensions.cmake:48 (include)\n  /opt/ros/jazzy/share/rosidl_cmake/cmake/rosidl_generate_interfaces.cmake:280 (ament_execute_extensions)\n  CMakeLists.txt:19 (rosidl_generate_interface)\n\nI think the actual line/file given is a red herring though, as repeating this process without any ros2-java involved does not lead to an error from the file listed. However the issue it points out seems to be real, as I did have success building ros2 from source i.e. having ros2-java always be involved in the generation of header files for interfaces. So it seems the existence of builtin_interfaces a binary in the ros2 jazzy install causes a conflict when rebuilding it in an overlaying workspace with ros2-java, specifically I suppose in rosidl_generator_java. ","author":{"url":"https://github.com/EGAlberts","@type":"Person","name":"EGAlberts"},"datePublished":"2026-01-13T13:54:31.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/250/ros2_java/issues/250"}