[tahoe-dev] Is TGPPL compatible with Apache license?

[Zooko O'Whielacronx]

It's so confusing.

Yuanz's original question was ambiguous: is he asking whether it is
legal to build a derived work out of Apache-licensed (Swift) code
combined with GPL-or-TGPPL-licensed (Zfec) code? Or is he asking
whether it is legal to build a derived work out of Apache-licensed
code, combined with GPL-or-TGPPL-licensed code, combined with
proprietary code? The answer is yes to the former and no to the latter
[*].

Hope this helps!

Re: Greg Troxel's letter. I'm sorry the licensing and governance of
Tahoe-LAFS is currently so ill-documented. I understand it all, and it
is all fine with me. There is no organization (certainly not my
company, https://LeastAuthority.com!) which has special rights to the
mainline Tahoe-LAFS codebase or which has too much influence over the
direction of the open source project.

But, it being all clear in _my_ head is not sufficient for other
people. It needs to be written down. I think Peter Secor (head of
Tahoe-LAFS Software Foundation) should probably be the one to do the
writing. I'll ask him to collaborate with me on a document or wiki
page or something.

Regards,

Zooko

[* Well, with some caveats. No, it is not legal to make a derived work
combining Zfec and proprietary software, except:

Caveat 1: If you are using Zfec under the terms of the GPL, what
copyright law actually forbids is *redistribution* of a GPL-derived
work without permission. So if you make a derived work combining Zfec
and proprietary software, but you don't redistribute it, then you do
not have to satisfy the other obligations of the GPL because you do
not need the GPL-rights-holder's permission to redistribute since you
aren't redistributing. That's why Spideroak can use Zfec in their
proprietary server-side software even though they don't GPL their
entire server-side codebase.

Caveat 2: If instead you are using Zfec under the terms of the TGPPL,
the TGPPL allows you to make a derived work combining TGPPL-licensed
and proprietary software and keep the resulting work proprietary, as
long as you release it under the TGPPL within 12 months.]