Re: Can I use CRoaring library in Git?

From: Jakub Narębski <jnareb@gmail.com>
Date: Jul 18, 2022, 11:13 UTC
Message-ID: <85r12iu10e.fsf@gmail.com>
In-Reply-To: <CAPOJW5x4McofC5fxBvsRAzum28wmeDJCMTMRmY_0oy=32JjKqQ@mail.gmail.com>

Abhradeep Chakraborty <chakrabortyabhradeep79@gmail.com> writes:

> Hello,
>
> I need the CRoaring[1] library to use roaring bitmaps. But it has
> Apache license v2 which is not compatible with GPLv2[2].

Actually Apache License v2.0 *is* compatibile with GPLv2 and GPLv3 in the sense that you can include the Apache licensed code (like the CRoaring library) in the GPLv2 project (like Git).

Quote from the cited "Apache License V2.0 and GPL Compatibility"[2]:

  The Free Software Foundation considers the Apache License, Version 2.0
  to be a free software license, compatible with version 3 of the GPL.
  The Software Freedom Law Center provides practical advice for
  developers about including permissively licensed source.

  Apache 2 software can therefore be included in GPLv3 projects, because
  the GPLv3 license accepts our software into GPLv3 works. However,
  GPLv3 software cannot be included in Apache projects. The licenses are
  incompatible in one direction only, and it is a result of ASF's
  licensing philosophy and the GPLv3 authors' interpretation of
  copyright law.

License compatibility is directional.

See also "The Free-Libre / Open Source Software (FLOSS) License Slide"[3] by David A. Wheeler which shows which licenses are compatibile with which, as a directed graph

[3] https://dwheeler.com/essays/floss-license-slide.html

Show 7 quoted lines

>
> Is there a way to use the CRoaring library in Git? Taylor told me that
> contrib/persistent-https tree is also licensed under Apache License
> version 2.
>
> [1] https://github.com/RoaringBitmap/CRoaring
> [2] https://www.apache.org/licenses/GPL-compatibility.html