Populate message info for intra-process messages

[thomasmoore-torc]

rclcpp: Populate message info for intra-process messages

Branch: intra-process-message-info (this repo: ros2/rclcpp)
Related PR: #3272 — "Iterate over IntraProcessBuffer instead of creating a vector" (intra-process-reduce-copies). See Landing order below — no functional dependency, but the two touch overlapping code.

Summary

Subscriptions that receive a message via intra-process delivery currently get a default-constructed, empty rmw_message_info_t — no sequence number, no publisher GID, no from_intra_process flag. The same subscription receiving the same message via inter-process (rmw) delivery gets a fully populated one. Anything relying on message_info (deduplicating by publisher GID, checking from_intra_process, etc.) behaves inconsistently depending on whether a given publish happens to stay in-process or not.

This populates message_info for intra-process messages too, so subscribers see consistent, meaningful info regardless of delivery path.

Changes

• Populate message info for intra-process messages — threads an rmw_message_info_t alongside the message through the intra-process publish path (Publisher::do_intra_process_publish/do_intra_process_ros_message_publish_and_return_shared → IntraProcessManager → IntraProcessBuffer → subscription).
  • IntraProcessBuffer storage changes from a bare shared_ptr/unique_ptr to a bundled IntraProcessBufferData (message + rmw_message_info_t), added with a copy constructor that deep-copies the unique-ptr alternative (needed so get_all_data()-based paths, e.g. transient-local replay, keep working with move-only storage).
  • Fixes do_transient_local_publish to correctly convert between shared/unique storage and shared/unique subscription requests via std::visit instead of assuming the two always match.
• Move IntraProcessBufferData to its own header — pulls the new struct out into intra_process_buffer_data.hpp to keep intra_process_buffer.hpp focused and avoid a circular-ish coupling between buffer and data definitions.
• Update intra-process unit tests — updates test_intra_process_buffer.cpp and test_intra_process_manager.cpp for the new Data/IntraProcessBufferData API and adds coverage for message-info propagation across both shared- and unique-ownership subscriptions.

Compatibility

Internal to rclcpp's intra-process implementation (rclcpp::experimental::*); no public API signature changes. Behavior change: intra-process subscribers now observe non-default message_info where they previously saw an empty one.

Testing

Built and tested against rolling in a ros:rolling-ros-base container via colcon build/colcon test for rclcpp (3091 tests, 0 failures), plus uncrustify/cpplint lint targets. All green.

Landing order

intra-process-reduce-copies (opened separately) touches the same files (intra_process_buffer.hpp, intra_process_manager.hpp, and both intra-process test files) as part of an unrelated copy-reduction optimization. The two branches are independently buildable and testable, but not free to merge in either order without a rebase — real textual conflicts exist between them (confirmed via a trial merge). No functional dependency either way; whichever of the two merges second will need to reconcile against the other.

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