Re: GnuTLS in Debian

[Simon McVittie <smcv@debian.org>]

On 11/01/14 17:37, Игорь Пашев wrote:
> Do I understand correctly the following:
> 
> Application M under the MIT license linked to LGPL3 library L - ok
> Application C under the CDDL license linked to LGPL3 library L - ok
> Application G under the GPL3 license linked to LGPL3 library L - ok,
> all under GPL3
> 
> Bang!
> 
> Application M is now under the GPL3 ?
> Application C is now illegally linked to L ?

No. As far as I understand the FSF's statements on how they intend the
GPL and shared libraries to interact[1]:

* the {M,C,G,L} source code is under the {MIT,CDDL,...} license

* the binary compiled from L is a separate work (let's call it L')
  which is a derivative work of L, and is also under the LGPL3

* the binary compiled from M and linked with L' is a Combined Work M'
  whose effective license is, or closely resembles, the LGPL3 (because
  it's a derivative work of both M and L', and the LGPL3 is more
  restrictive than MIT)

* the binary compiled from C and linked with L' is a Combined Work C'
  whose license is complicated (you may do anything with it that
  would be allowed by both the CDDL *and* the LGPL3)

* the binary compiled from G and linked with L' is a Combined Work G'
  containing G and L, whose effective license is the GPL3
  (because the GPL3 has more restrictions / fewer exceptions than the
  LGPL3)

(where "Combined Work" is as defined in the LGPL3).

The GPL3's requirement that you distribute G' under the more restrictive
terms of the GPL3 does not affect how you may distribute L'.

Regards,
    S

[1] I am not a lawyer, so I am not qualified to assess whether this is
    how any particular country's copyright law actually works. However,
    it seems the closest to a canonical answer that you're likely
    to get.