Revisiting the PHP binding license issues

Hello,

I would like to see Xapian used more widely in the PHP community. The major
obstacle is that binaries of the PHP extension cannot be distributed. I've
been reading earlier discussions on this and wonder if there's now an
option.

My starting points were
https://trac.xapian.org/wiki/FAQ/PHP%20Bindings%20Package and the
discussion at https://trac.xapian.org/ticket/191.

One comment int he discussion is:

> So the PHP bindings don't link in any PHP licensed code, but they do
> compile against PHP licensed headers. I'm not a lawyer, but I think this is
> the only remaining potential problem.


The GPL FAQ says at
https://www.gnu.org/licenses/gpl-faq.html#GPLIncompatibleLibs that there is
scope for adding exceptions when building against incompatible libraries.

Given that only the PHP bindings compile against the PHP licensed headers,
can the PHP bindings alone:
a) be relicensed under GPLv3, and grant an additional permission under
section 7?
b) remain GPLv2 and add a specific exception?

If so, this would allow Xapian to remain GPLv2+ licenced, and yet the PHP
bindings to be distributed pre-compiled.

I've searched the Debian legal archives for precedence one way or the
other, but (ironically) the search isn't great at returning relevant
results.

Peter

Other references:
https://xapian.org/docs/bindings/php7/
https://lists.debian.org/debian-legal/2009/04/msg00101.html