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

Matthias Kilian kili at outback.escape.de
Sun Sep 20 08:08:28 UTC 2009

On Sun, Sep 20, 2009 at 07:51:09AM +0900, Jason Dagit wrote:
> > 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.
> 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.

For case 2: putting mere modifications under a different license
than the original work (made by someone else) isn't very practical
IMHO, unless the modifications are a complete reimplementation of
the original work.

> 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.

No, if the modification happens *after* the relicensing, there's
no problem. It may be problematic if he wants to relicense his code
after there have been significant modifications made by others. But
this isn't the case for GZCRCs.lhs, since there are only trivial
changes made by others (two minor fixes by Eric Kow, and the final
drop of the legacy zlib by Petr Rockai, which just removes code
from GZCRCs.lhs).

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

The only problematic situation in this special case (GZCRCs.lhs)
would be if someone adds significant modifications to the "old"
(GPLed) version and refuses to put those modifications under the
3-clause BSD license. But I don't see why anyone should do this.
After all, the original author clearly expressed his will to change
the license of his code to BSD3, and anyone who works with this
code should respect the authors will.

However, should there already exist non-trivial modifications before
the change of the license, then those modifications of course can
be used and distributed under the terms of the GPLv2+.


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