Example of single package containing both ros1 and ros2 code

src/bar_ros/CMakeLists.txt

@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 3.5.0)
+project(bar_ros)
+
+find_package(catkin QUIET)
+find_package(ament_cmake QUIET)
+
+if (catkin_FOUND)
+  include(ros1/ros.cmake)
+elseif(ament_cmake_FOUND)
+  include(ros2/ros.cmake)
+else()
+  message(FATAL_ERROR "ROS build tool not found.")
+endif()

src/bar_ros/package.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<package format="3">
+  <name>bar_ros</name>
+  <version>0.0.1</version>
+  <description>The bar package</description>
+
+  <maintainer email="[email protected]">rre</maintainer>
+  <license>BSD</license>
+
+  <buildtool_depend condition="$ROS_VERSION == 1">catkin</buildtool_depend>
+  <depend condition="$ROS_VERSION == 1">roscpp</depend>
+
+  <buildtool_depend condition="$ROS_VERSION == 2">ament_cmake</buildtool_depend>
+  <depend condition="$ROS_VERSION == 2">rclcpp</depend>
+  <test_depend condition="$ROS_VERSION == 2">ament_lint_auto</test_depend>
+  <test_depend condition="$ROS_VERSION == 2">ament_lint_common</test_depend>
+
+  <depend>lib_foo</depend>
+
+  <export>
+    <build_type condition="$ROS_VERSION == 1">catkin</build_type>
+    <build_type condition="$ROS_VERSION == 2">ament_cmake</build_type>
+  </export>
+</package>

src/bar_ros/ros1/ros.cmake

@@ -0,0 +1,29 @@
+find_package(catkin REQUIRED COMPONENTS
+  roscpp
+)
+
+find_package(lib_foo REQUIRED)
+
+catkin_package(
+#  INCLUDE_DIRS include
+#  LIBRARIES bar_ros1
+#  CATKIN_DEPENDS lib_foo roscpp
+#  DEPENDS system_lib
+)
+
+include_directories(
+# include
+  ${catkin_INCLUDE_DIRS}
+  ${lib_foo_INCLUDE_DIRS}
+)
+
+add_executable(${PROJECT_NAME}_node ros1/src/bar_node.cpp)
+target_link_libraries(${PROJECT_NAME}_node
+  ${catkin_LIBRARIES}
+  ${lib_foo_LIBRARIES}
+)
+install(TARGETS ${PROJECT_NAME}_node
+  ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
+  LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
+  RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
+)

src/bar_ros/ros2/ros.cmake

@@ -0,0 +1,39 @@
+# Default to C99
+if(NOT CMAKE_C_STANDARD)
+  set(CMAKE_C_STANDARD 99)
+endif()
+
+# Default to C++14
+if(NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 14)
+endif()
+
+if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+  add_compile_options(-Wall -Wextra -Wpedantic)
+endif()
+
+# find dependencies
+find_package(ament_cmake REQUIRED)
+find_package(rclcpp REQUIRED)
+find_package(lib_foo REQUIRED)
+
+include_directories(include ${lib_foo_INCLUDE_DIRS})
+
+add_executable(${PROJECT_NAME}_node ros2/src/bar_node.cpp)
+ament_target_dependencies(${PROJECT_NAME}_node rclcpp)
+target_link_libraries(${PROJECT_NAME}_node ${lib_foo_LIBRARIES})
+
+install(TARGETS ${PROJECT_NAME}_node DESTINATION lib/${PROJECT_NAME})
+
+if(BUILD_TESTING)
+  find_package(ament_lint_auto REQUIRED)
+  # the following line skips the linter which checks for copyrights
+  # uncomment the line when a copyright and license is not present in all source files
+  #set(ament_cmake_copyright_FOUND TRUE)
+  # the following line skips cpplint (only works in a git repo)
+  # uncomment the line when this package is not in a git repo
+  #set(ament_cmake_cpplint_FOUND TRUE)
+  ament_lint_auto_find_test_dependencies()
+endif()
+
+ament_package()