LGPL 2.1 + GPL 3 = problems?

Philippe Verdy verdy_p at wanadoo.fr
Sun Jul 15 11:53:17 UTC 2007

De : Arnoud Engelfriet [mailto:arnoud at engelfriet.net] :
> What I meant is that you can apply the terms of the GPL to any
> LGPL work instead of the LGPL terms. See LGPL 2 section 3, first
> sentence.

Note the exact statement is:
	"(If a newer version than version 2 of the ordinary GNU General
	Public License has appeared, then you can specify that version
	instead if you wish.)"

But it is not cleared enough to explicitly state which "newer version" of
the GPL is usable, notably because it does not explicitly say if it is
valid. What makes the statement clear is "as published by the Free Software
Foundation" in the copyright notice.

These contestable terms (because it could include any other licence
compatible with the GPLv2, including one containing some terms not published
by the FSF itself) were revised in GPLv3 (section 14) and LGPLv3, by
explaining where such extended permission can be found:

	"If the Program specifies that a certain numbered version of the
	GNU General Public License “or any later version” applies to it,
	you have the option of following the terms and conditions either
	of that numbered version or of any later version published by the
	Free Software Foundation. If the Program does not specify a
	version number of the GNU General Public License, you may choose
	any version ever published by the Free Software Foundation."

This statement explicitly makes additional restrictions to the future
versions of the GPL (in the sense of section 10 of the GPLv3), as explained
in the following paragraphs in that section 14 of the GPLv3.

This interpretation was confirmed by the FSF, and justified the need to
include an upgrade to the referenced version of the GPL, to be fair with
what was done with the LGPLv2 in the past (when used in combination with
other non-FSF but compatible licenses).


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