cannot link mimick : /usr/bin/ld: cannot find -lmimick about rclcpp HOT 2 OPEN

i think that because you are trying to build rclcpp without rclcpp test dependent packages.

Theoretically, this should work. That is, it is a supported use case to overlay just rclcpp on top of binary packages, and successfully compile it. The following should work:

$ . /opt/ros/iron/setup.bash
$ mkdir -p rclcpp_ws/src
$ cd rclcpp_ws
$ git clone -b iron https://github.com/ros2/rclcpp src/rclcpp
$ colcon build --allow-overriding rclcpp rclcpp_action rclcpp_components rclcpp_lifecycle

And indeed, it does work for me, on Rolling, Iron, and Humble, but with a caveat. When I first tried this out, I had already done source /opt/ros/iron/setup.bash, but then I installed ros-iron-mimick-vendor as part of installing dependencies. When I did that, I got the same error as @ericxiaoxin . If I sourced /opt/ros/iron/setup.bash again, though, it started working.

So I would say that this is a bug, but probably not an urgent one because it does work by resourcing /opt/ros/iron/setup.bash

from rclcpp.

i think that because you are trying to build rclcpp without rclcpp test dependent packages.

can you try with,

colcon build --packages-up-to rclcpp rclcpp_action rclcpp_components rclcpp_lifecycle

from rclcpp.