Re: apache2 and gpl2+
On 31/08/14 17:54, Johannes Schauer wrote:
> As it is pointed out here  and here , GPL2 is incompatible with Apache2
> but GPL3 projects can contain Apache2 licensed code. Since vcmi is licensed
> GPL2+, could the Debian package upgrade the license to GPL3+ and thus turn it
> into a GPL3 project with Apache2 code which should be compatible? Sorry if this
> is stupid, it's just a naive idea.
(All answers are on the basis of your statements about the license being
accurate: I know nothing about vcmi.)
That general reasoning works, but you don't have to "upgrade" the
license or anything. The way to think about it is: who has the right to
say what you may do, and what did they say?
The copyright holder of fuzzylite (more precisely, the fuzzylite source
code) says you may copy it, as long as you don't do anything not allowed
by the Apache license v2.
The copyright holder of vcmi (more precisely, the parts of the vcmi
source code other than fuzzylite) says you may copy it, as long as you
don't do anything not allowed by any of the GPL2, or the GPL3, or a
hypothetical future GPL version.
OK, that's the source. What about the binaries? They are a derivative
work of both vcmi and fuzzylite source code, so you may only do things
that are allowed by both the vcmi copyright holders, and the fuzzylite
copyright holders. In other words, the license is "you must obey the
GPL2 or later, and simultaneously obey the Apache license v2".
The GPL2 says you can only copy under GPL2 if the source code for the
whole thing is under terms no more restrictive than GPL2, and the Apache
license v2 has terms more restrictive than that, so, no go: this
combination of licenses would place impossible requirements on you.
However, the GPL3 says you can only copy under GPL3 if the source code
for the whole thing is under terms no more restrictive than (GPL3 + a
few restrictions), and the Apache license v2 fits in those few
restrictions, so it is possible to comply with the terms of both the
GPL3 and the Apache license v2 simultaneously. Both of these licenses
let you do everything the DFSG requires, so that's good enough for Debian.
The license applicable to the binaries is still not GPL-3, though - it
is ((GPL-2 or GPL-3 or ...) and Apache-2.0). The practical result is the
same as ((GPL-3 or ...) and Apache-2.0), but it matters if you're going
to extract GPL-2+ bits and combine them with something GPL-2.