update signature for added pub/sub options

[eboasson]

This relates to ros2/rmw#187.

Before merging, it'd probably be best to make a "dashing" branch.

Signed-off-by: Erik Boasson eb@ilities.com

[dirk-thomas]

I would suggest holding off on branch and get ros2/rmw#188 (comment) resolved first. Than you should be easily able to keep supporting both ROS distros from the same branch.

[wjwwood]

Looks right to me.

[rotu]

I wasn't able to find a solution with type reflection or SFINAE to make it cross-compatible, but I think I found a decent enough alternative using #ifdefs:

eboasson#1

[rotu]

I figured out how to do this cleanly with SFINAE! I prefer this approach, but I'll leave you guys to choose.

eboasson#2

A few tricks:

1. The extern "C" linkage specifier only needs to be on the function declaration in the rmw.h header and will link the matching overload.
2. I had to declare the new types (e.g. rmw_subscription_options_t) to be template parameters, so that they don't trigger an unknown type name.
3. Where I used new properties of existing classes, I had to replace the class name (e.g. rmw_subscription_t) with a template argument so it views it as a substitution failure instead of a missing member.

[eboasson]

@rotu, on macOS it breaks 😞 ... but now there is ros2/rmw#188 and that's a clean solution.

[rotu]

Good to know. What’s the failure on MacOS?

[eboasson]

I get this:

This error state is being overwritten:

  'failed to resolve symbol 'rmw_create_publisher' in shared library '/Users/erik/ros2_ws/install/rmw_cyclonedds_cpp/lib/librmw_cyclonedds_cpp.dylib', at /Users/erik/ros2_ws/src/ros2/rmw_implementation/rmw_implementation/src/functions.cpp:163'

with this new error message:

  'failed to resolve symbol 'rmw_create_subscription' in shared library '/Users/erik/ros2_ws/install/rmw_cyclonedds_cpp/lib/librmw_cyclonedds_cpp.dylib', at /Users/erik/ros2_ws/src/ros2/rmw_implementation/rmw_implementation/src/functions.cpp:163'

And checking the contents of the library with nm /Users/erik/ros2_ws/install/rmw_cyclonedds_cpp/lib/librmw_cyclonedds_cpp.dylib | grep -E 'rmw_create_(publisher|subscriber)' I only see scary mangled names:

0000000000005950 T __Z20rmw_create_publisherPK10rmw_node_tPK29rosidl_message_type_support_tPKcPK17rmw_qos_profile_t
00000000000425a0 d __ZZ20rmw_create_publisherPK10rmw_node_tPK29rosidl_message_type_support_tPKcPK17rmw_qos_profile_tE26__rcutils_logging_location

[eboasson]

Closing because #51 sorted it out