On Tue, Jun 8, 2010 at 09:12, Yusuke ENDOH <mame / tsg.ne.jp> wrote:
>
> Though I think "or GPLv3" is much better if matz allows,
> I'll commit the following patch unless there is objection:

[...]
>
> +DO NOT LINK Ruby WITH A LIBRARY WHOSE LICENSE IS NOT COMPATIBLE WITH Ruby
> +License (see COPYING).
> +For example, currently you cannot link with readline6, which is under GPLv3.
> +

The wording here is incorrect, and I think reflects a misunderstanding
of the GPL (and GPL v3).

The GNU Public License is *not* an EULA. You do not have to agree to
it in order to download and use GPL-licensed software. As David Jones
points out at <http://drj11.wordpress.com/2008/02/25/the-gnu-gpl-is-not-an-eula/>,
the license itself states that "Activities other than copying,
distribution and modification are not covered by this License; they
are outside its scope. The act of running the Program is not
restricted".

So it is perfectly legal for me to link Ruby with any number of GPL3
libraries, including readline6, and to use that copy of Ruby as much
as I wish. The only thing I cannot do is *distribute* a version of
Ruby which has been linked with readline6.

In addition, I cannot distribute Ruby linked with a library unless I
comply with all of the license terms. So libraries I link and
distribute must be compatible with *both* the GPL and the alternative
Matz license terms in http://www.ruby-lang.org/en/LICENSE.txt

This means that you can't link and distribute GPL2 libraries under the
Ruby license either, so you can't use versions of readline prior to
readline6 either.

So the wording should be more like this:

---
  DO NOT DISTRIBUTE Ruby WITH A LIBRARY WHOSE LICENSE IS NOT
COMPATIBLE WITH EITHER SET OF Ruby LICENSE TERMS (see COPYING).

 For example, currently you cannot distribute Ruby linked with any
version of GNU readline, under the original Ruby license terms; you
must distribute Ruby linked with readline under the GPL. You cannot
distribute Ruby linked with readline6 at all, because it uses GPL v3,
and Ruby is not yet approved for GPLv3 licensing.

 You can link Ruby with any GPL or GPLv3 licensed software and use it;
you just may not be able to distribute it if you do so.
---


mathew
--
<URL:http://www.pobox.com/~meta/>