Rclcpp template metaprogramming bug. Help wanted

JM_ROS · February 26, 2024, 9:54am

Hi,
we hit a bug in the function traits that is out of my league.
If you are really good with template metraprogramming, please have a look at:

github.com/ros2/rclcpp

AnySubscriptionCallback doesn't accept `std::bind` callbacks with bound arguments

opened 09:56AM - 20 Feb 24 UTC

HovorunB

## Bug report **Required Info:** - Operating System: - Ubuntu 22.04 - …Installation type: - from source - Version or commit hash: - rolling - DDS implementation: - Fast-RTPS - Client library (if applicable): - rclcpp #### Steps to reproduce issue 1) Build rclcpp on a version after https://github.com/ros2/rclcpp/pull/1928 2) Try to build for example [foxglove-bridge](https://github.com/foxglove/ros-foxglove-bridge) #### Expected behavior `std::bind(&FoxgloveBridge::rosMessageHandler, this, channelId, clientHandle, _1),` [(source)](https://github.com/foxglove/ros-foxglove-bridge/blob/89239eb5bbb8549fec08ade82254fabcf773cc37/ros2_foxglove_bridge/src/ros2_foxglove_bridge.cpp#L535-L538) is cast to `std::function` from [any_subscription_callback.hpp](https://github.com/ros2/rclcpp/blob/10252e9f66ac87f3903f301b64320d32457f0658/rclcpp/include/rclcpp/any_subscription_callback.hpp#L416) #### Actual behavior ![Screenshot from 2024-02-19 10-56-06](https://github.com/ros2/rclcpp/assets/87417416/56f16069-6ab4-4a4d-ae28-a9865cafaf17) #### Additional information For example `std::bind(&Class::method, this, std::placeholders::_1)` (without bound arguments) will build fine We also were able to fix the issue by casting the callback to `std::function` before passing it to the subscription ``` auto subscriber = this->create_generic_subscription( topic, datatype, qos, static_cast<std::function<void(std::shared_ptr<rclcpp::SerializedMessage>)>>(std::bind(&FoxgloveBridge::rosMessageHandler, this, channelId, clientHandle, _1)), subscriptionOptions); ``` Is this how it is supposed to be done now, or is there a bug in casting std::bind from any_subscription_callback.hpp?

Thanks.

system · March 27, 2024, 9:55am

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Rclcpp template metaprogramming bug. Help wanted

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