> LibreDWG was licensed GPLv3-or-later and it didn’t help FreeCAD one bit. The problem is that FreeCAD isn't licensed under GPLv2-or-later. But LibreDWG's code

> LibreDWG was licensed GPLv3-or-later and it didn’t help FreeCAD one bit. The problem is that FreeCAD isn't licensed under GPLv2-or-later. But LibreDWG's code can be used under a GPLv4 (when it comes out) license, so at least you don't have two cases of this problem. > it would not have improved the ZFS situation at all. Yes, because Sun intentionally created a GPL-incompatible license and Oracle continues to perpetuate that. What's really troubling is that the Sun folks take it as a point of pride that their license is GPL-incompatible and don't consider it to have been a mistake. > When LibreDWG provides DWG file parsing, but is licensed in such a way that FreeCAD cannot use it, users cannot use it. If we're going to play the "theoretical software that might've been written" game, then I could argue that not copylefting your software also indirectly encumbers users because the users' friends may start using a proprietary version of a free software program that is incompatible. > The Free Software Definition doesn’t divide people into groups of “users” and “developers, who are not users." Developers are users. And developers have the same set of freedoms as users. However, there are certain privileges that developers can also have that don't make sense to users -- those privileges are not essential freedoms under the Free Software Definition. "The right to create a fork under another license" does not appear in the Free Software Definition, no matter how you try to twist it. Developers are allowed to link software against a library under a free license, they just have to follow the license rules. Now, if they (or other developers) have made license choices that restrict them in that department it's not the fault of the license. Is it a shame when that happens? Absolutely. But talking about how lax licenses solve all of these problems (while dismissing the downsides) is just being disingenuous. We have a perfect case study of copyleft working -- the Oracle proprietarisation of OpenSolaris. Had OpenSolaris been under a lax license, Oracle would probably still own the technical talent for Solaris (and it would have become a large proprietary software machine). That didn't happen because of copyleft.