Implement proper C++ visibility support?

[claudiofantacci]

Implement C++ visibility support as described here.

This will probably allow us to remove this Windows-specific CMake instruction.

An example of this implementation can be found in YARP in conf/api.h used, e.g., in os/api.h.

[traversaro]

The CMake's macro GenerateExportHeader may also be useful.

A thing that is typically tricky to get right is to correctly disable the visibility flags on Windows when building a static library. Related discussion: ros/console_bridge#40 (comment) .

[claudiofantacci]

@traversaro great, thanks for your feedback. I'll have a look at it and see what I can do 👍
I'll write here any thought I will have during the process.

[claudiofantacci]

@traversaro, the GenerateExportHeader macro seems super cool and capable of handling the static library issue with little more effort.
I will try using it and, if succesful, include it in our how-to-export-cpp-library with the proper documentation 👍

[traversaro]

Yes. To be honest I think that for most cases in research code the benefit of a clean list of symbols is not worth the overhead of making sure that the visibility macros are properly used, but this is probably a decision that it make sense to do on a per-project basis.

[claudiofantacci]

Yes. To be honest I think that for most cases in research code the benefit of a clean list of symbols is not worth the overhead of making sure that the visibility macros are properly used, but this is probably a decision that it make sense to do on a per-project basis.

100% agree 🚀

[traversaro]

The issue robotology/icub-main#577 is a good example of issue that would be avoided if CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS was used instead of manually adding visibility decorators.