disclaimer: I'm not a lawyer, this is just my understanding of the licenses.
On 2020/05/01 06:28:56, hanwenn wrote: > Technologically speaking, this is a brilliant idea, and I am all in favor it. > > However, I think we can't enable this by default. > > Ghostscript is licensed under AGPL, and linking it in makes LilyPond a derived > work, putting it under AGPL as well. That would be effectively a license change > of LilyPond, which would need consent of the current authors, and I think the > Scorio folks would not be happy with. To put this on a solid basis, here's a quote from https://www.gnu.org/licenses/gpl-3.0.html 13. Use with the GNU Affero General Public License. Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such. So I disagree that this is a license change as the "terms of this License will continue to apply to the part which is the covered work". LilyPond stays licensed under GPLv3. But yes "the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such". And here's the point that many have long argued about and continue to disagree: What is "combination"? Linking to a library clearly is (and it's even spelled out explicitly), but what about other "control flows" like calling GhostScript. Here's another quote: The “Corresponding Source” for a work in object code form means all the source code needed to generate, install, and (for an executable work) run the object code and to modify the work, including scripts to control those activities. However, it does not include the work's System Libraries, or general-purpose tools or generally available free programs which are used unmodified in performing those activities but which are not part of the work. For example, Corresponding Source includes interface definition files associated with source files for the work, and the source code for shared libraries and dynamically linked subprograms that the work is specifically designed to require, such as by intimate data communication or control flow between those subprograms and other parts of the work. So the first sentence and the example seem to include runtime dependencies ("subprograms"), but others (like System Libraries) are excluded. I don't know whether this applies to GhostScript, but I'd argue that it's not a "major essential component" of the OS. So in my opinion, LilyPond + GS already is AGPL if you're using a recent version of the software. > I suggest we make this an option that you have enable explicitly. If it is > enabled, we'd have to change the --license output to say AGPL as well. I'm open to making this change if people prefer. The major benefit will be for documentation builds anyway, so the "normal" usage of LilyPond is fine with forking. https://codereview.appspot.com/548030043/
