License Committee Report for July 2007

[John Cowan]

Wilson, Andrew scripsit:

> Look specifically at the case of a GPLv2-only program
> linking to an LGPLv3 library where the "system library" exception does
> not apply.  GPLv2 says the entire Combined Work
> falls under its copyleft.  This is trivially easy with an LGPLv2
> library, since the library can be automatically relicensed as GPLv2.

That's true, but that's not *why*.  An LGPLv2 library may, under section
6 of the LGPLv2, be combined or linked with a work that uses it under any
terms of your choice (provided modification of the library and reverse
engineering are permitted), including the GPLv2 (which is required by
the license on the work using the library).

> On the other hand, the LGPLv3 library is in fact GPLv3 with extra
> permissions which may be stripped away to leave bare GPLv3 ... which
> wants the entire Combined Work to be licensed under *its* copyleft,
> which FSF says is incompatible with GPLv2's.  Conflict of licenses
> ensues.

You *may* strip the LGPLv3-specific permissions, but nothing requires
you to do so.  Under clause 4 of the LGPLv3, you may instead distribute
the Combined Work under terms of your choice (with the same proviso).
These terms will be the GPLv2 once again.  No license conflict.

> Now look at the case of linking a proprietary program with the same
> LGPLv3 library.  Since one of those additional permissions is to bound
> the scope of v3 copyleft from spreading to the entire Combined Work,
> no conflict of licenses.

I agree.

-- 
There is no real going back.  Though I          John Cowan
may come to the Shire, it will not seem         cowan at ccil.org
the same; for I shall not be the same.          http://www.ccil.org/~cowan
I am wounded with knife, sting, and tooth,
and a long burden.  Where shall I find rest?           --Frodo