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Re: Bug #189164: libdbd-mysql-perl uses GPL lib, may be used by GPL-incompatible apps

Steve Langasek wrote:
>This assumes that the FSF's interpretation depends on the claim that
>dynamic linking creates a derived work.  While varies parties have
>claimed this at one point or another, I have argued that the >dynamically linked work is under the purview of the GPL by virtue of >the license terms alone, *if* you are distributing the GPL library in >question, which is always the case for Debian.

Well, this statement is simply wrong, and I'll devote the rest of this email to explaining why.

If the dynamic linking does *not* create a derived work, you are distributing two works:
A. The new program which links to the GPL'ed library
B. The GPL'ed library which is linked to

Not one work.  A "mere aggregaton" of two works.

Under the GPL, the library B is distributable under section 3, using either the written offer (b) or the distribution of source code (a), and the source code for the library can be distributed under section 1.

There is no restriction on the distribution of B with other works. In fact, there's an explicit statement that there's no such restriction (Section 2, final paragraph). So the GPL imposes no restriction on the distribution of A and B together. Note carefully that *all* the restrictions in the GPL (except for the very mild section 1 restrictions) are stated in terms of "incorporating parts of the Program", "as part of a whole which is a work based on the Program", etc., all of which are terms refering to the creation of a derived work.

Steve said:
>"You have no say in it, it's not a derived work" is a
>null argument, because as distributors we must accept the terms of a
>license that *gives* them a say in it.
Wrong. The license, in the case of the GPL, *doesn't* give them a say in it.

Some other, theoretical, license, *could* impose such a restriction (a la the BSD advertising clause), but the GPL simply *doesn't* impose such restrictions.

The "dynamic linking imposes GPL" is, fundamentally, based on the idea that dynamic linking creates a derived work. I'm quite sure the FSF lawyers will agree with me on that.

Furthermore, it is not within the rights of the copyright holder to decide unilaterally what constitutes a derived work. I believe that is considered to be a matter of facts, to be established by court cases and precedents.

Respecting the FSF's *opinion* that dynamic linking creates a derived work is perfectly sensible and wise. (Hey, they could be legally correct!) Claiming that the GPL somehow imposes itself on works linked with even if linking *doesn't* legally create a derived work is just plain wrong.


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