inquery about "GPL with commercial exception"

[Jeff Epler]

On Tue, Sep 29, 2015 at 05:14:11PM +0200, IOhannes m zmölnig (Debian/GNU) wrote:
> i'm currently thinking about packaging "linuxsampler", which has a
> somewhat abominable license, which they call "GPL with commercial
> exception" [1].
> 
> [1] https://www.linuxsampler.org/downloads.html#exception

For discussion, the text in question from the linuxsampler website reads:

 [*] LinuxSampler is licensed under the GNU GPL with the exception that
 USAGE of the source code, libraries and applications FOR COMMERCIAL
 HARDWARE OR SOFTWARE PRODUCTS IS NOT ALLOWED without prior written
 permission by the LinuxSampler authors. If you have questions on the
 subject, that are not yet covered by the FAQ, please contact us. 

I think this is more a *prohibition* (something permitted by the GPL,
use for any purposes, is prohibited) than an *exception*.

The page also says that a mandatory dependency of LinuxSampler, libgig,
is licensed under GPL without prohibition.

In my opinion:
 - GPL with additional use prohibition is not DFSG-compatible
 - GPL with additional use prohibition is not GPL-compatible

As a consequence of the second item, I believe LinuxSampler is not
distributable at all, since it works only by linking GPL-compatible and
GPL-incompatible code together into a single work, so I don't believe
that LinuxSampler can be distributed even in the non-free archive.

Jeff