Re: [boost] BOOST license & GPL

Subject: Re: [boost] BOOST license & GPL
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2017-04-01 22:48:36

On Sun, Apr 2, 2017 at 1:13 AM, Niklas Angare via Boost
<boost_at_[hidden]> wrote:
> "Andrey Semashev via Boost" wrote:
>> On Sat, Apr 1, 2017 at 9:22 PM, Niklas Angare via Boost
>> <boost_at_[hidden]> wrote:
>>>
>>> It would feel better to me if
>>> they said "this is licensed under the GPL and, in part, other compatible
>>> licenses".
>>
>> It doesn't work like that. A product, as a whole, must be distributed
>> under a single license. (It can be distributed under multiple
>> licenses, e.g. proprietary and copyleft, but that is another off-topic
>> case; each such distribution is independent and whole.)
>
> Why does the whole source package have to be distributed under a single
> license?

Because the package is distributed as a whole. There is a common set
of rights and restrictions on that package which constitutes the
license.

A package is probably the wrong term here, because we tech people tend
to imagine it as a set of files, which could potentially have
different licenses. I believe, the lawyer language uses the term work,
which is understood as an atomic entity, an item with associated value
and terms of use. At least, that's how I see it.

>> As I understand it, a license, among other things, defines two sets: a
>> set of rights granted to the user, and a set of restrictions or
>> obligations imposed on the user. Two licenses are compatible if the
>> sets defined by the licenses are non-contradictory and can be
>> fulfilled combined. BSL is less restrictive than GPL, and in order for
>> the two of the licenses to be fulfilled the code must be distributed
>> under the GPL. It doesn't make that BSL part on its own licensed under
>> the GPL (or rather, you cannot enforce GPL on that part because the
>> original copyright holders did not allow that).
>
> The requirement that the entire BSL be included is not a part of the GPL, so
> for that particular detail the BSL is more restrictive than the GPL.

GPL also requires to distribute a copy of the license. Similar
requirement of BSL does not contradict the GPL.

My point is if you have Foo under BSL and Bar under GPL and you want
to distribute FooBar then you have to fulfill both BSL and GPL. You
can do this if you include BSL in the source code and distribute
FooBar under the GPL.