Dual license the source code under MIT/APACHE

[Urgau]

Hello, I want this change to be done for two reasons:

• First, the Rust port is as of time of writing in an awkward position
  because he is dual license under MIT/APACHE instead of only the
  APACHE license. This change in license should fix this problem.
• Second, and the most convincing reason for this change to occurred is
  that some discussion as taken place with the Rust Libs Team
  to integrate the Rust port directly into the Rust standard library.
  And for that to happend the change in license is required because
  the code for the Rust repository is dual license against MIT/APACHE.

Peoples who needs to agree to this change (based on code change only):

• @lemire
• @biojppm
• @eugenegff
• @kitaisreal
• @wojdyr
• @nealrichardson
• @timkpaine

[timkpaine]

I transfer any rights of my tiny change over to @lemire, you can remove me from the list.

[lemire]

I do not think anyone could object to this change, and I am happy to merge. Because we are not a formal organization, the reasonable approach is just to wait some time, to give people a chance to object if they'd like, and then merge.

I would point out that, as far as I can see, there is really no reason for the Rust version to have the same license as the C++ version. I'd like to remind us that there is no copyright on ideas, coding patterns, algorithms or mathematical results. And the Rust code is distinctly different.

[eugenegff]

I transfer any rights of my tiny change over to @lemire, you can remove me from the list too

[wojdyr]

me too (transferring any right to @lemire)

[kitaisreal]

I transfer any rights of my tiny change over to @lemire.

[lemire]

The test failure is bogus, evidently, see #71

[Urgau]

The test failure is bogus, evidently, see #71

+1 I have rebase against main, updated a little bit the commit message and force force (squash). Now the workflows should all be green.

[Urgau]

I would point out that, as far as I can see, there is really no reason for the Rust version to have the same license as the C++ version. I'd like to remind us that there is no copyright on ideas, coding patterns, algorithms or mathematical results. And the Rust code is distinctly different.

@lemire Yes I agree but the issue is not on copyright but on the license of the source code. This repository use the Apache 2 license, this license defined what the license call "Derived Works", this include translations (both to a different natural language and to a different programming language), but it is not entirely clear how (and if any of) the requirements from the Apache license should be applied when the "Derived Works" is so radically different from the original source.

However what is clear is that under the clause 4.c and 4 (end):

(c) You must retain, in the Source form of any Derivative Works
that You distribute, all copyright, patent, trademark, and
attribution notices from the Source form of the Work,
excluding those notices that do not pertain to any part of
the Derivative Works

You may add Your own copyright statement to Your modifications and
may provide additional or different license terms and conditions
for use, reproduction, or distribution of Your modifications, or
for any such Derivative Works as a whole, provided Your use,
reproduction, and distribution of the Work otherwise complies with
the conditions stated in this License.

Every "Derivative Works" must also be license under the Apache 2 license and that re-licensing can be done but only if the license "complies with the conditions stated in this License" which is not the case for the MIT license.
Given this, the fact that the Rust port is actually using the MIT License and if we considered that a port in a different language falls under the "Derived Works", this means that the licensing with the MIT license of the Rust port may not be completely legal.

Given everything else and the fact that the code for the Rust repository is dual license against MIT/APACHE, I think that the Rust peoples might be a little be conservative about what falls under "Derived Works".

In conclusion, dual licensing this source code prevents potential licensing issues with the Rust port and permit the integration of it in the Rust standard library.

Source: License terms when porting free software to another language

PS: I may be completly wrong, in that case do not hesitate to contradict my words.

[nealrichardson]

No objection from me

[lemire]

We are just missing @biojppm.

I am sure he will agree, it is simply a matter of getting him to notice us.

[lemire]

@Urgau It seems that you are right, legally speaking.

Maybe I should start defaulting on the MIT license then?

[Urgau]

@Urgau It seems that you are right, legally speaking.

Maybe I should start defaulting on the MIT license then?

You mean only on MIT ? Because with this pull request the code will be under the MIT and APACHE licenses at the option of the one how use it.

But I would suggest to keep MIT/APACHE for "patent" issue. Josh Triplett said:

Requiring both MIT and Apache 2.0 as inbound licenses for contributions means that anyone making a contribution is providing the Apache 2.0 patent grant. And then having MIT and Apache 2.0 as outbound licenses people can use Rust under means that Rust provides widespread compatibility with all sorts of other FOSS licenses, including GPLv2.

[lemire]

@Urgau I was thinking about new (future) projects. Ok. MIT + Apache could be a good default in the future.

[Urgau]

@Urgau I was thinking about new (future) projects. Ok. MIT + Apache could be a good default in the future.

Oh, sorry for misinterpreted your question. In that case, yes MIT + Apache should be a pretty good default for your (and probably most peoples) future projects.

[biojppm]

Sorry for the delay. Indeed I do agree.

[joshtriplett]

Thank you very much!

@lemire @Urgau
This is a tangent for this request, but:
Rust primarily uses the MIT OR Apache-2.0 dual-license because it was the best available option at the time Rust was started to provide a permissive license with an explicit patent grant while preserving widespread compatibility (including with GPLv2). Today, there's a much simpler license for that: https://opensource.org/licenses/BSDplusPatent . That's pretty much 2-clause BSD with the Apache 2.0 patent grant added, and it's GPLv2-compatible. Folks involved with early Rust have said that if that license existed at the time, they would have used it instead. That may help you for new projects.

(For this project, we really appreciate you being willing to match the license of Rust, to simplify integration of the derived Rust version. Thank you!)

[lemire]

https://opensource.org/licenses/BSDplusPatent

Looks good.