[darcs-users] darcs patch: relicense Darcs.Commands.GZCRCs as BSD3

Gwern Branwen gwern0 at gmail.com
Sun Sep 20 13:38:57 UTC 2009

On Sat, Sep 19, 2009 at 6:51 PM, Jason Dagit <dagit at codersbase.com> wrote:
> On Wed, Sep 16, 2009 at 5:12 AM, Ganesh Sittampalam <ganesh at earth.li> wrote:
>> Hi,
>> I would like my contributions to darcs to be licensed under
>> BSD3 to assist integration with general Haskell infrastructure
>> and with camp. It's not practical to annotate every file I've
>> contributed to, but this one I wrote initially so it might as
>> well change.
>> Any other of my contributions, in the past or future, are also
>> hereby offered under a BSD3 licence. If I ever revoke this
>> declaration I will post to the mailing list to say so. (Obviously
>> any revocation could only apply to contributions made after that.)
> My only question about doing this is:  Can you really license your changes
> to Darcs as BSD3 where they are changes to existing GPL'd code?  I thought
> that the GPL applies to derivative works is why I ask.  So, if I'm
> understanding it correctly, then I think what you're trying to do only makes
> sense for 1) bits where you are the original author of the that bit 2)
> modifications to darcs where the previous authors agree to release their
> changes as BSD3.

Yes, he can. But you're also right: confusingly, what he would've done
in such a case is *dual*-licensing: his changes are BSD, the original
is GPL, and the result is BSD+GPL, but note, not just either - since
BSD adds no restrictions compared to GPL, we can essentially simplify
it to GPL. This is akin to a Wikipedia editor putting his edits and
articles under CC-BY, in addition to Wikipedia's standard
GFDL/CC-BY-SA; the legal distinction is there, but in practice, it
doesn't mean anything except for new works or works where the entire
history (=the whole chain of derivative works) has been relicensed.

(To continue the Wikipedia example: what are you going to do with an
edit which is both BY and BY-SA? You can pick which license you want
to use the edit under, but what *do* you do with just a diff? But it's
valuable if that edit is creating a 100 page article single-handedly,
since now you have an entire article in 2 flavors.)

> Another case I'm unclear about is when you are the OA (original author) of a
> chunk and then someone who hasn't agreed to relicense as BSD3 changes
> something in your code.  In that case, I think you'd have to revert (and
> rewrite) instead of just rewriting if you want to keep it BSD3.


> Just something to think about.  I don't object to any of this relicensing,
> I'm just trying to understand how it works.
> Jason

If copyright were a proposed type system, it'd be rejected for being
logically incoherent. :) We can but try to work & live with it as best
we can.


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