cdrtools - GPL code with CDDL build system

[Eduard Bloch <edi@gmx.de>]

Hello debian-legal experts ;-),

I need a bit support to clarify the issue with cdrtools' build system.

Summary: a while ago, Joerg Schilling (upstream) replaced the copyright
headers in the files of his build system inside of the cdrtools package
with references to a CDDL license context.

In #350739, the reporter claims that we and JS are violating the GPL
because not all files required to create the executable work are
available under the GPL license.

CDDL is considered GPL-incompatible for linking with GPLed code.
Discussion with upstream in hope to make it double-licensed was not very
fruitfull. He defines his tarball as "medium" (in terms of our
DFSG!) where the two parts of the software (code and build system) are
allowed to coexist, and if we would not allow that, then we had prooved
that GPL violates the DFSG (because it infects other software on the
same "medium", hahaha).

Now the question: how GPL-compatible should we consider this CDDL-like
license? See http://www.gnu.org/licenses/license-list.html for details.

We have the option of splitting the source package into code (GPLed)
and meta-code (CDDL). Would that be suitable for main?

The case seems similar to the famous "GPL code needing non-free build
tool", but this time to build system is not that non-free.

Eduard.