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Re: One unclear point in the Vim license

On Thu, Jan 03, 2002 at 11:21:19AM +0100, Bram Moolenaar wrote:

> Thomas Bushnell wrote:
>> Glenn Maynard <g_dlegal@zewt.org> writes:

>>> I notice Vim in testing links against libgpm, which is GPL (according
>>> to /usr/doc/libgpmg1/copyright).  Is this a problem, Vim's license being
>>> GPL-incompatible?  (http://www.gnu.org/philosophy/license-list.html) I'm
>>> not entirely clear on what can link to GPL libraries and when.

>> Certainly the current Vim license is GPL-incompatible.  (Even if we
>> decided it's free after all, it's definitely not ok to link it against
>> a GPLd library.)

> I don't see how you can call a GPL'ed library "free" if it's not allowed
> to compile it together with other software.

The GPL license is specifically written with provisions that ensure the 
freeness of derived works.  The GPL always allows you to link a GPL 
library against other code if 1) you do not distribute or publish the
combined work, or 2) you distribute the combined work under the GPL.  If
you cannot or choose not to distribute the other code under the GPL
(for instance, because you do not hold the copyright to it and its
license is incompatible with the GPL), then this is not the fault of the
author of the GPL code.

The term "free software" is used to refer to specific kinds of freedoms
regarding software and source code.  At least as far as the term is used
in the GNU/Linux community[1], this doesn't imply the freedom to
relicense the code however you want, although there are some free
licenses that do permit this.  One metric of freedom holds that software
in the public domain is the most free, because you can use public domain
software any way you want to.  But the authors of the GPL are more
pragmatic, as I suspect you yourself are, given that Vim is not in the
public domain: the GPL does place some limits on the freedom of users,
but it does so only to encourage a global net gain in the freeness of
software.  Sometimes, achieving this goal requires a local loss in
freedom; it is not always possible to link free software against GPL
software, but this is a necessary sacrifice given the goals of the GPL.  
And it is never possible to link non-free software to GPL libraries, 
because this is contrary to the goals of the GPL.

Steve Langasek
postmodern programmer

[1] Referring here to the community that has grown up around GNU 
software and the Linux kernel, which is an apt characterization even if 
you don't believe in calling the system GNU/Linux :)

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