Misc fastrtps typesupport generator cleanup

[sloretz]

This cleans up a bunch of stuff to do with the generators for rosidl_typesupport_fastrps_c and rosidl_typesupport_fastrtps_cpp

• Make sure to find_package() dependencies needed by generated code
• Made rosidl_typesupport_fastrtps_cpp find_package rosidl_generator_cpp so it generates files first
• Avoid calling ament_export_dependencies(...) when SKIP_INSTALL is used.
  • This means moving a few calls out of CMakeLists.txt and into the generator's CMake code
• Don't wrap the target_compile_definitions(...BUILDING_DLL...) line in an if(WIN32) block because it's unnecessary. The visibility header seems to do stuff on other platforms too.
• Add checks that generated targets exist from the generators these generators depend on
• Use target_link_libraries() instead of ament_target_dependencies() Is ament_target_dependencies() still necessary? ament/ament_cmake#292 in a couple places
• When a generator depends on another, make it target_link_libraries() to the generated target of the other rather than hard-coding the directory it's likely to create in the build folder
• Remove an unnecessary dependency between the target generated by rosidl_typesupport_fastrtp_c and the target generated by rosidl_typesupport_fastrtps_cpp
• When target_link_libraries() on targets from this generator in dependency packages, use the ..._TARGETS${_target_suffix} variable instead of the ..._LIBRARIES${_target_suffix}
  • also use rosidl_export_typesupport_targets() where it wasn't already
• Remove if(NOT _generated_headers... checks - because they don't seem to do anything
• Reviewed and organized the package.xmls with comments

Depends on ros2/rmw_dds_common#57

[sloretz]

CI (build: all test: --packages-select rosidl_typesupport_fastrtps_c rosidl_typesupport_fastrtps_cpp test_msgs rcl_interfaces)

• Linux
• Linux-aarch64
• Windows

[sloretz]

Marked as draft while I open other PRs. So far in my local testing it seems fixing these issues requires fixing up cmake issues in rmw_dds_common which requires fixing up cmake issues in rosidl_typesupport_c which requires the cmake fixes in ros2/rosidl#662 .

[sloretz]

Depends on ros2/rmw_dds_common#57

[sloretz]

@hidmic I've added you as a reviewer, but this one depends on ros2/rmw_dds_common#57 which depends on ros2/rosidl_typesupport#123 which depends on ros2/rosidl#662, so I've left it marked as a draft until those are merged.

[hidmic]

LGTM once this comes out of draft mode

[sloretz]

Leaving in draft until ros2/rosidl_typesupport#123 and then ros2/rmw_dds_common#57 are merged.

[sloretz]

CI (build: --packages-above-and-dependencies rosidl_typesupport_fastrtps_c rosidl_typesupport_fastrtps_cpp test: --packages-select rosidl_typesupport_fastrtps_c rosidl_typesupport_fastrtps_cpp)

• Linux
• Linux-aarch64
• Windows