Hello!

As some of you might be aware, copyright law and precendence in the EU show a bit of a difference in the FOSS license landscape compared to for example the US. Particularly, I am talking about linking in the context of derivative work. I tried to do some research here, but I didn't manage to find any conclusive articles or discussions on the matter.

As both dynamic and static linking in the EU is generally considered as a question of interoperability rather than derivative work, linking-wise virality of licenses like GPL are basically void over here. The EUPL license (my license of choice) as per my understanding even explicitly claims that "derivative work" is a definition out of scope of the license text due to this. I today read about additional possible AGPL violations uncovered from BambuLab regarding not opensourcing a .so library that the software uses. This made me wonder: what stops someone from taking a copyleft project in the EU, and adding all their heavy modifications basically as callouts to a proprietary dynamic library? Do I only have to publish the modified source full of single line callouts, without the library source?