[boost] GPL compatibility etc.

From: John Maddock (john_at_[hidden])
Date: 2004-05-07 05:36:18

It seems on reading the GPL FAQ and in particular
http://www.gnu.org/licenses/gpl-faq.html#GPLIncompatibleLibs, that:

The GPL normally extends itself to all of the program * including all
library dependencies *, I'll leave aside the issue of whether this is legal,
and instead point out the section which reads:

"If you want your program to link against a library not covered by that
exception, you need to add your own exception, wholly outside of the GPL.
This copyright notice and license notice give permission to link with the
program FOO:
  Copyright (C) yyyy <name of copyright holder>

  This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your option)
any later version.

  This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.

  You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc., 59
Temple Place, Suite 330, Boston, MA 02111-1307 USA

  In addition, as a special exception, <name of copyright holder> gives
permission to link the code of this program with the FOO library (or with
modified versions of FOO that use the same license as FOO), and distribute
linked combinations including the two. You must obey the GNU General Public
License in all respects for all of the code used other than FOO. If you
modify this file, you may extend this exception to your version of the file,
but you are not obligated to do so. If you do not wish to do so, delete this
exception statement from your version.

Only the copyright holders for the program can legally authorize this
exception. If you wrote the whole program yourself, then assuming your
employer or school does not claim the copyright, you are the copyright
holder--so you can authorize the exception. But if you want to use parts of
other GPL-covered programs by other authors in your code, you cannot
authorize the exception for them. You have to get the approval of the
copyright holders of those programs. "

The last paragraph is particularly odious it seems to me, especially if you
are trying to combine Boost with GPL'ed libraries into one GPL whole.

One final point, I note that some libraries under non-GPL licences contain
explicit exceptions along the lines of:

"4. If PCRE is embedded in any software that is released under the GNU
   General Purpose Licence (GPL), or Lesser General Purpose Licence (LGPL),
   then the terms of that licence shall supersede any condition above with
   which it is incompatible."

But having said that, the new Boost License seems to be most like the
licenses that the GPL folks consider to be "compatible", so maybe we just
need to hasten the provision of the new License to all of Boost.

John.