[BUG] multiple definition of visionary::VisionaryControl::kSessionTimeout

[arrfou99]

I get a multiple definition error that I never got before which is not clear to me why!

After checking it looks like there are two kSessionTimeout defined where we have this constant defined two times:

sick_visionary_cpp_base/src/VisionaryControl.cpp

Line 27 in a2361e4

constexpr std::chrono::seconds VisionaryControl::kSessionTimeout;

sick_visionary_cpp_base/src/VisionaryControl.h

Line 36 in a2361e4

static constexpr std::chrono::seconds kSessionTimeout = std::chrono::seconds(5);

in order to avoid this error I had to remove the line VisionaryControl.cpp and use this in the VisionaryControl.h

 static constexpr std::chrono::seconds kSessionTimeout = std::chrono::seconds(5);

[peichtoSICKAG]

Hi arrfou99,

during our current release process, we noticed this issue again.
according to c++ spec a static constexpr data member which could be accessed via its memory address during runtime needs this additional declaration. Thus we did not change anything within the 1.1.0 release.
In our build matrix MSVC2022 compiler version 19.x, mingw x64 gcc 14.2 and linux native gcc 11.4 we did not face any problems.
If I remember correctly however, there were severeal changes regarding constexpr behaviour between different c++ standard versions.
Thus if you would like to add a combination of compiler / c++ standard where this is a problem we could consider making this conditional for the next release.
Otherwise we'd like to close this issue.

Sincerely
peichtoSICKAG

[robclaes]

I'm having the same issue while integrating this into ROS2 (humble) on default Ubuntu 22 ROS Docker container. In an Ubuntu24 ROS2 (Jazzy) this does not cause an error. Both of them are using the ROS2 colcon build environment.

[xfealal]

Hello @robclaes,

We failed to reproduce the error while building this repo inside the two Docker containers (Ubuntu 22 + Humble and Ubuntu 24 + Jazzy). Could you provide a minimal reproducible example (ROS2 with colcon) so we have a common starting point?

Your help is much appreciated.

[robclaes]

I have tried to create a minimal example on https://github.com/robclaes/sick_minimal_example

[flugi]

I dealt with this issue by modifying the CMakeLists file in the library from C++11 to C++17, which was enough modification for me (I also needed the fPIC g++ to add, but that is another issue), but it is a bad sign that C++20 setting does not compile.

Visionary lib links fine when both sides are C++11 or C++17, and I get multiple definition errors when the lib is built with the repository current setting C++11 while the program is built with C++17 or above.

(g++ 13.3.0)

[xfealal]

Hello @flugi and @robclaes,

We have reached the same diagnosis. However, since our codebase was developed using C++11, we do not see a direct way to resolve this issue, as it is not within our control to influence the language standards of the consuming parts during integration.

We recommend you ensure that the same language standard is used throughout the entire process for compilation.

As of now, there is no plan or decision on when or if the codebase will be migrated to a newer C++ standard.

Best regards