Bug#505224: RFP: freecad -- An extensible CAx program (alpha)

[Denis Barbier <bouzim@gmail.com>]

On 2009/2/10, Adam C Powell IV wrote:
[...]
> The issue here is that FreeCAD links to Coin3D which is GPL, and to Open
> CASCADE which is OCTPL [1] and is not GPL-compatible.  The Coin3D
> developers refuse to make a GPL exception for Open CASCADE [2].  And I
> have never been able to reach anyone at Open CASCADE for any purpose
> (was the maintainer of the Debian package), except indirectly via the
> Forum.
>
> [1] http://www.opencascade.org/occ/license/
> [2] https://jira.sim.no/browse/COINSUPPORT-425
>
> So unless they separate the Coin3D and Open CASCADE linkages into
> independent binaries, FreeCAD will unfortunately not be distributable
> for the foreseeable future. :-(
> Robert, I owe you an answer on why the OCTPL is GPL-incompatible.
> IANAL, TINLA, TINASOTODP, etc. but here goes:
>      * 4. para 4: "If you distribute or sublicense the Software (as
>        modified by You or on Your behalf as the case may be), You cause
>        such Software to be licensed as a whole, at no charge, to all
>        third parties..."  The GPL does not require "at no charge", and
>        even expressly allows charging for software, so this is an
>        additional restriction beyond the GPL.

GPL 2, section 2.b)
    You must cause any work that you distribute or publish, that in
    whole or in part contains or is derived from the Program or any
    part thereof, to be licensed as a whole at no charge to all third
    parties under the terms of this License.

>      * 4. para 5: "You document all Your Modifications, indicate the
>        date of each such Modifications, designate the version of the
>        Software You used..."  None of this is required by the GPL, so
>        all of these are additional restrictions.

GPL 2, section 2.a)
    You must cause the modified files to carry prominent notices
    stating that you changed the files and the date of any change.

To me, OCTPL 6.3 (as found in OpenCascade sources, not the one
at the website, which is outdated IIRC) is identical to LGPL 2.1, they
paraphrased it, and I believe that OCTPL 6.3 is compatible with GPL.

Denis