llvm dev - Aug 2017 - Relicensing: Revised Developer Policy

Hi all,

Now that we’ve settled on the license legalese to get to, we need to start the
process of relicensing.  We’re still sorting through all of the details of what
this will take, but the first step is clear: new contributions to LLVM will need
to be under both the old license structure and the new one (until the old
structure is completely phased out).  From a mechanical perspective, this is
pretty simple, but I want to make sure that the community is aware of this and
has time to digest and discuss any concerns.

In order to spell out what this will look like, we’ve gone ahead and revised
http://llvm.org/docs/DeveloperPolicy.html to reflect what the new structure will
look like.  While the license text is the canonical truth, the DeveloperPolicy
serves a few purposes: it explains to non-lawyers what the license means,
provides rationale for the design, and deals with relicensing process topics.

I’ve attached a draft of the revised document below.  Please take a look and let
me know if anything should be further clarified or if you have any other
questions and comments.  Thanks!

-Chris





Copyright, License, and Patents
==============================
.. note::

   This section deals with legal matters but does not provide legal advice.  We
   are not lawyers --- please seek legal counsel from a licensed attorney.

This section addresses the issues of copyright, license and patents for the LLVM
project.  The copyright for the code is held by the contributors of
the code.  The code is licensed under permissive `open source licensing terms`_,
namely the Apache 2 license, which includes a copyright and `patent license`_.
When you contribute code to the LLVM project, you license it under these terms.

If you have questions or comments about these topics, please contact the
`LLVM Developer's Mailing List <mailto:llvm-dev at lists.llvm.org>`_. 
However,
please realize that most compiler developers are not lawyers, and therefore you
will not be getting official legal advice.

Copyright
---------

The LLVM project does not collect copyright assignments, which means that the
copyright for the code in the project is held by the respective contributors.
Because you (or your company)
retain ownership of the code you contribute, you know it may only be used under
the terms of the open source license you contributed it under: the license for
your contributions cannot be changed in the future without your approval.

Because the LLVM project does not require copyright assignments, changing the
LLVM license requires tracking down the
contributors to LLVM and getting them to agree that a license change is
acceptable for their contributions.  We feel that a high burden for relicensing
is good for the project, because contributors do not have to fear that their
code will be used in a way with which they disagree.

Relicensing
-----------

The last paragraph notwithstanding, the LLVM Project is in the middle of a large
effort to change licenses, which aims to solve several problems:

* The old licenses made it difficult to move code from (e.g.) the compiler to
  runtime libraries, because runtime libraries used a different license from the
  rest of the compiler.
* Some contributions were not submitted to LLVM due to concerns that
  the patent grant required by the project was overly broad.
* The patent grant was unique to the LLVM Project, not written by a lawyer, and
  was difficult to determine what was protection was provided (if any).

The scope of relicensing is all code that is considered part of the LLVM
project, including the main LLVM repository, runtime libraries (compiler_rt,
OpenMP, etc), Polly, and all other subprojects.  There are a few exceptions:

* Code imported from other projects (e.g. Google Test, Autoconf, etc) will
  remain as it is.  This code isn't *developed* as part of the LLVM project,
it
  is *used* by LLVM.
* Some subprojects are impractical or uninteresting to relicense (e.g. llvm-gcc
  and dragonegg). These will be split off from the LLVM project (e.g. to
  separate Github projects), allowing interested people to continue their
  development elsewhere.

To relicense LLVM, we will be seeking approval from all of the copyright holders
of code in the repository, or potentially remove/rewrite code if we cannot.
This is a large
and challenging project which will take a significant amount of time to
complete.  In the interim, **all contributions to the project will be made under
the terms of both the new license and the legacy license scheme** (each of which
is described below).  The exception to this is the legacy patent grant, which
will not be required for new contributions.

When all of the code in the project has been converted to the new license or
removed, we will drop the requirement to contribute under the legacy license.
This will achieve the goal of having
a single standardized license for the entire codebase.

If you are a prior contributor to LLVM and have not done so already, please do
*TODO* to allow us to use your code. *Add a link to a separate page here, which
is probably a click through web form or something like that.  Details to be
determined later*.


.. _open source licensing terms:

New LLVM Project License Framework
----------------------------------

Contributions to LLVM are licensed under the `Apache License, Version 2.0
<https://www.apache.org/licenses/LICENSE-2.0>`_, with two limited
exceptions intended to ensure that LLVM is very permissively licensed.
Collectively, the name of this license is "Apache 2.0 License with LLVM
exceptions".  The exceptions read:

::

   ---- LLVM Exceptions to the Apache 2.0 License ----

   As an exception, if, as a result of your compiling your source code, portions
   of this Software are embedded into an Object form of such source code, you
   may redistribute such embedded portions in such Object form without complying
   with the conditions of Sections 4(a), 4(b) and 4(d) of the License.

   In addition, if you combine or link compiled forms of this Software with
   software that is licensed under the GPLv2 ("Combined Software") and
if a
   court of competent jurisdiction determines that the patent provision (Section
   3), the indemnity provision (Section 9) or other Section of the License
   conflicts with the conditions of the GPLv2, you may retroactively and
   prospectively choose to deem waived or otherwise exclude such Section(s) of
   the License, but only in their entirety and only with respect to the Combined
   Software.


We intend to keep LLVM perpetually open source and available under a permissive
license - this fosters the widest adoption of LLVM by
**allowing commercial products to be derived from LLVM** with few restrictions
and without a requirement for making any derived works also open source.  In
particular, LLVM's license is not a "copyleft" license like the
GPL.

The "Apache 2.0 License with LLVM exceptions" allows you to:

* freely download and use LLVM (in whole or in part) for personal, internal, or
  commercial purposes.
* include LLVM in packages or distributions you create.
* combine LLVM with code licensed under every other major open source
  license (including BSD, MIT, GPLv2, GPLv3...).
* make changes to LLVM code without being required to contribute it back
  to the project - contributions are appreciated though!

However, it imposes these limitations on you:

* You must retain the copyright notice if you redistribute LLVM: You cannot
  strip the copyright headers off or replace them with your own.
* Binaries that include LLVM must reproduce the copyright notice (e.g. in an
  included README file or in an "About" box), unless the LLVM code was
added as
  a by-product of compilation.  For example, if an LLVM runtime library like
  compiler_rt or libc++ was automatically included into your application by the
  compiler, you do not need to attribute it.
* You can't use our names to promote your products (LLVM derived or not) -
  though you can make truthful statements about your use of the LLVM code,
  without implying our sponsorship.
* There's no warranty on LLVM at all.

We want LLVM code to be widely used, and believe that this provides a model that
is great for contributors and users of the project.  For more information about
the Apache 2.0 License, please see the `Apache License FAQ
<http://www.apache.org/foundation/license-faq.html>`_, maintained by the
Apache Project.


.. note::

   The LLVM Project includes some really old subprojects (dragonegg,
   llvm-gcc-4.0, and llvm-gcc-4.2), which are licensed under **GPL
   licenses**.  This code is not actively maintained - it does not even
   build successfully.  This code is cleanly separated into distinct SVN
   repositories from the rest of LLVM, and the LICENSE.txt files specifically
   indicate that they contain GPL code.  When LLVM transitions from SVN to Git,
   we plan to drop these code bases from the new repository structure.


.. _patent license:

Patents
-------

Section 3 of the Apache 2.0 license is a patent grant under which
contributors of code to the project contribute the rights to use any of
their patents that would otherwise be infringed by that code contribution
(protecting uses of that code).  Further, the patent grant is revoked
from anyone who files a patent lawsuit about code in LLVM - this protects the
community by providing a "patent commons" for the code base and
reducing the
odds of patent lawsuits in general.

The license specifically scopes which patents are included with code
contributions.  To help explain this, the `Apache License FAQ
<http://www.apache.org/foundation/license-faq.html>`_ explains this scope
using
some questions and answers, which we reproduce here for your convenience (for
reference, the "ASF" is the Apache Software Foundation, the guidance
still
holds though)::

   Q1: If I own a patent and contribute to a Work, and, at the time my
   contribution is included in that Work, none of my patent's claims are
subject
   to Apache's Grant of Patent License, is there a way any of those claims
would
   later become subject to the Grant of Patent License solely due to subsequent
   contributions by other parties who are not licensees of that patent.

   A1: No.

   Q2: If at any time after my contribution, I am able to license other patent
   claims that would have been subject to Apache's Grant of Patent License
if
   they were licenseable by me at the time of my contribution, do those other
   claims become subject to the Grant of Patent License?

   A2: Yes.

   Q3: If I own or control a licensable patent and contribute code to a specific
   Apache product, which of my patent claims are subject to Apache's Grant
of
   Patent License?

   A3:  The only patent claims that are licensed to the ASF are those you own or
   have the right to license that read on your contribution or on the
   combination of your contribution with the specific Apache product to which
   you contributed as it existed at the time of your contribution. No additional
   patent claims become licensed as a result of subsequent combinations of your
   contribution with any other software. Note, however, that licensable patent
   claims include those that you acquire in the future, as long as they read on
   your original contribution as made at the original time. Once a patent claim
   is subject to Apache's Grant of Patent License, it is licensed under the
   terms of that Grant to the ASF and to recipients of any software distributed
   by the ASF for any Apache software product whatsoever.


Legacy License Structure
------------------------

.. note::
   The code base was previously licensed under the Terms described here.
   We are in the middle of relicensing to a new approach (described above), but
   until this effort is complete, the code is also still available under these
   terms.  Once we finish the relicensing project, new versions of the code will
   not be available under these terms.  However, nothing takes away your right
   to use old versions under the licensing terms under which they were
   originally released.

We intend to keep LLVM perpetually open source and to use a permissive open
source license.  The code in
LLVM is available under the `University of Illinois/NCSA Open Source License
<http://www.opensource.org/licenses/UoI-NCSA.php>`_, which boils down to
this:

* You can freely distribute LLVM.
* You must retain the copyright notice if you redistribute LLVM.
* Binaries derived from LLVM must reproduce the copyright notice (e.g. in an
  included README file).
* You can't use our names to promote your LLVM derived products.
* There's no warranty on LLVM at all.

We believe this fosters the widest adoption of LLVM because it **allows
commercial products to be derived from LLVM** with few restrictions and without
a requirement for making any derived works also open source (i.e. LLVM's
license is not a "copyleft" license like the GPL). We suggest that you
read the
`License <http://www.opensource.org/licenses/UoI-NCSA.php>`_ if further
clarification is needed.

In addition to the UIUC license, the runtime library components of LLVM
(**compiler_rt, libc++, and libclc**) are also licensed under the `MIT License
<http://www.opensource.org/licenses/mit-license.php>`_, which does not
contain
the binary redistribution clause.  As a user of these runtime libraries, it
means that you can choose to use the code under either license (and thus
don't
need the binary redistribution clause), and as a contributor to the code that
you agree that any contributions to these libraries be licensed under both
licenses.  We feel that this is important for runtime libraries, because they
are implicitly linked into applications and therefore should not subject those
applications to the binary redistribution clause. This also means that it is ok
to move code from (e.g.)  libc++ to the LLVM core without concern, but that code
cannot be moved from the LLVM core to libc++ without the copyright owner's
permission.

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On 08/07/2017 08:53 AM, Chris Lattner via llvm-dev
wrote:
> Hi all,
> 
> Now that we’ve settled on the license legalese to get to, we need to start
the process of relicensing.  We’re still sorting through all of the details of
what this will take, but the first step is clear: new contributions to LLVM will
need to be under both the old license structure and the new one (until the old
structure is completely phased out).  From a mechanical perspective, this is
pretty simple, but I want to make sure that the community is aware of this and
has time to digest and discuss any concerns.
> 
> In order to spell out what this will look like, we’ve gone ahead and
revised http://llvm.org/docs/DeveloperPolicy.html to reflect what the new
structure will look like.  While the license text is the canonical truth, the
DeveloperPolicy serves a few purposes: it explains to non-lawyers what the
license means, provides rationale for the design, and deals with relicensing
process topics.
> 
> I’ve attached a draft of the revised document below.  Please take a look
and let me know if anything should be further clarified or if you have any other
questions and comments.  Thanks!
> 
> -Chris
> 
> 
> 
> 
> 
> 
> Copyright, License, and Patents
> ==============================> 
> .. note::
> 
>    This section deals with legal matters but does not provide legal advice.
We
>    are not lawyers --- please seek legal counsel from a licensed attorney.
> 
> This section addresses the issues of copyright, license and patents for the
LLVM
> project.  The copyright for the code is held by the contributors of
> the code.  The code is licensed under permissive `open source licensing
terms`_,
> namely the Apache 2 license, which includes a copyright and `patent
license`_.
> When you contribute code to the LLVM project, you license it under these
terms.
> 
> If you have questions or comments about these topics, please contact the
> `LLVM Developer's Mailing List <mailto:llvm-dev at
lists.llvm.org>`_.  However,
> please realize that most compiler developers are not lawyers, and therefore
you
> will not be getting official legal advice.
> 
> Copyright
> ---------
> 
> The LLVM project does not collect copyright assignments, which means that
the
> copyright for the code in the project is held by the respective
contributors.
> Because you (or your company)
> retain ownership of the code you contribute, you know it may only be used
under
> the terms of the open source license you contributed it under: the license
for
> your contributions cannot be changed in the future without your approval.
> 
> Because the LLVM project does not require copyright assignments, changing
the
> LLVM license requires tracking down the
> contributors to LLVM and getting them to agree that a license change is
> acceptable for their contributions.  We feel that a high burden for
relicensing
> is good for the project, because contributors do not have to fear that
their
> code will be used in a way with which they disagree.
> 
> Relicensing
> -----------
> 
> The last paragraph notwithstanding, the LLVM Project is in the middle of a
large
> effort to change licenses, which aims to solve several problems:
> 
> * The old licenses made it difficult to move code from (e.g.) the compiler
to
>   runtime libraries, because runtime libraries used a different license
from the
>   rest of the compiler.
> * Some contributions were not submitted to LLVM due to concerns that
>   the patent grant required by the project was overly broad.
> * The patent grant was unique to the LLVM Project, not written by a lawyer,
and
>   was difficult to determine what was protection was provided (if any).
> 
> The scope of relicensing is all code that is considered part of the LLVM
> project, including the main LLVM repository, runtime libraries
(compiler_rt,
> OpenMP, etc), Polly, and all other subprojects.  There are a few
exceptions:
> 
> * Code imported from other projects (e.g. Google Test, Autoconf, etc) will
>   remain as it is.  This code isn't *developed* as part of the LLVM
project, it
>   is *used* by LLVM.
> * Some subprojects are impractical or uninteresting to relicense (e.g.
llvm-gcc
>   and dragonegg). These will be split off from the LLVM project (e.g. to
>   separate Github projects), allowing interested people to continue their
>   development elsewhere.
> 
> To relicense LLVM, we will be seeking approval from all of the copyright
holders
> of code in the repository, or potentially remove/rewrite code if we cannot.
> This is a large
> and challenging project which will take a significant amount of time to
> complete.  In the interim, **all contributions to the project will be made
under
> the terms of both the new license and the legacy license scheme** (each of
which
> is described below).  The exception to this is the legacy patent grant,
which
> will not be required for new contributions.
> 
> When all of the code in the project has been converted to the new license
or
> removed, we will drop the requirement to contribute under the legacy
license.
> This will achieve the goal of having
> a single standardized license for the entire codebase.
> 
> If you are a prior contributor to LLVM and have not done so already, please
do
> *TODO* to allow us to use your code. *Add a link to a separate page here,
which
> is probably a click through web form or something like that.  Details to be
> determined later*.
> 
> 
I had to read this paragraph a few times before I realized that this was a TODO
message for the author of the policy, and there was nothing for me (a prior
contributor) to do yet.  I would change this to something like:
" In the future we will have a mechanism for prior contributors to
re-license
their code ..."

-Tom

On 7 August 2017 at 16:53, Chris Lattner via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> When all of the code in the project has been converted to the new license
or
> removed, we will drop the requirement to contribute under the legacy
> license.
> This will achieve the goal of having
> a single standardized license for the entire codebase.
>
> If you are a prior contributor to LLVM and have not done so already, please
> do
> *TODO* to allow us to use your code. *Add a link to a separate page here,
> which
> is probably a click through web form or something like that.  Details to be
> determined later*.
Although the LLVM project and LLVM Foundation obviously can't give
legal advice, this page probably needs to be a little more than just a
web form. There is a wide variance in the level of understanding of
copyright and licensing issues across the developer community, even
open source contributors. As such, I think LLVM would benefit from
highlighting the sort of things contributors should be sure of before
submitting their permission, to ensure they have the authority to do
so. One scenario would be work-for-hire where permission was granted
to submit the code upstream, but copyright may still be held by the
client.

I'm really glad to see this re-licensing effort continuing to move
forwards. Thanks to everyone who has been working on it.

Best,

Alex

On Mon, Aug 7, 2017 at 11:48 PM Alex Bradbury via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> On 7 August 2017 at 16:53, Chris Lattner via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > When all of the code in the project has been converted to the new
> license or
> > removed, we will drop the requirement to contribute under the legacy
> > license.
> > This will achieve the goal of having
> > a single standardized license for the entire codebase.
> >
> > If you are a prior contributor to LLVM and have not done so already,
> please
> > do
> > *TODO* to allow us to use your code. *Add a link to a separate page
here,
> > which
> > is probably a click through web form or something like that.  Details
to
> be
> > determined later*.
>
> Although the LLVM project and LLVM Foundation obviously can't give
> legal advice, this page probably needs to be a little more than just a
> web form. There is a wide variance in the level of understanding of
> copyright and licensing issues across the developer community, even
> open source contributors. As such, I think LLVM would benefit from
> highlighting the sort of things contributors should be sure of before
> submitting their permission, to ensure they have the authority to do
> so. One scenario would be work-for-hire where permission was granted
> to submit the code upstream, but copyright may still be held by the
> client.
>
When we get to this point, we'll definitely be working with the lawyer for
the Foundation to make sure we get the legal things worked out correctly. I
think this TODO is just essentially a note for others that "something"
vetted by our lawyer will go here, not trying to forecast exactly what it
will be.
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Hi,

I still don't see any justification in the text why a license change is
required over having a contributor agreement including whatever patent
wording we want.

As such, I don't agree with it.

Cheers,
Rafael

Chris Lattner via llvm-dev <llvm-dev at lists.llvm.org> writes:
> Hi all,
>
> Now that we’ve settled on the license legalese to get to, we need to start
the process of relicensing.  We’re still sorting through all of the details of
what this will take, but the first step is clear: new contributions to LLVM will
need to be under both the old license structure and the new one (until the old
structure is completely phased out).  From a mechanical perspective, this is
pretty simple, but I want to make sure that the community is aware of this and
has time to digest and discuss any concerns.
>
> In order to spell out what this will look like, we’ve gone ahead and
revised http://llvm.org/docs/DeveloperPolicy.html to reflect what the new
structure will look like.  While the license text is the canonical truth, the
DeveloperPolicy serves a few purposes: it explains to non-lawyers what the
license means, provides rationale for the design, and deals with relicensing
process topics.
>
> I’ve attached a draft of the revised document below.  Please take a look
and let me know if anything should be further clarified or if you have any other
questions and comments.  Thanks!
>
> -Chris
>
>
>
>
>
> Copyright, License, and Patents
> ==============================>
> .. note::
>
>    This section deals with legal matters but does not provide legal advice.
We
>    are not lawyers --- please seek legal counsel from a licensed attorney.
>
> This section addresses the issues of copyright, license and patents for the
LLVM
> project.  The copyright for the code is held by the contributors of
> the code.  The code is licensed under permissive `open source licensing
terms`_,
> namely the Apache 2 license, which includes a copyright and `patent
license`_.
> When you contribute code to the LLVM project, you license it under these
terms.
>
> If you have questions or comments about these topics, please contact the
> `LLVM Developer's Mailing List <mailto:llvm-dev at
lists.llvm.org>`_.  However,
> please realize that most compiler developers are not lawyers, and therefore
you
> will not be getting official legal advice.
>
> Copyright
> ---------
>
> The LLVM project does not collect copyright assignments, which means that
the
> copyright for the code in the project is held by the respective
contributors.
> Because you (or your company)
> retain ownership of the code you contribute, you know it may only be used
under
> the terms of the open source license you contributed it under: the license
for
> your contributions cannot be changed in the future without your approval.
>
> Because the LLVM project does not require copyright assignments, changing
the
> LLVM license requires tracking down the
> contributors to LLVM and getting them to agree that a license change is
> acceptable for their contributions.  We feel that a high burden for
relicensing
> is good for the project, because contributors do not have to fear that
their
> code will be used in a way with which they disagree.
>
> Relicensing
> -----------
>
> The last paragraph notwithstanding, the LLVM Project is in the middle of a
large
> effort to change licenses, which aims to solve several problems:
>
> * The old licenses made it difficult to move code from (e.g.) the compiler
to
>   runtime libraries, because runtime libraries used a different license
from the
>   rest of the compiler.
> * Some contributions were not submitted to LLVM due to concerns that
>   the patent grant required by the project was overly broad.
> * The patent grant was unique to the LLVM Project, not written by a lawyer,
and
>   was difficult to determine what was protection was provided (if any).
>
> The scope of relicensing is all code that is considered part of the LLVM
> project, including the main LLVM repository, runtime libraries
(compiler_rt,
> OpenMP, etc), Polly, and all other subprojects.  There are a few
exceptions:
>
> * Code imported from other projects (e.g. Google Test, Autoconf, etc) will
>   remain as it is.  This code isn't *developed* as part of the LLVM
project, it
>   is *used* by LLVM.
> * Some subprojects are impractical or uninteresting to relicense (e.g.
llvm-gcc
>   and dragonegg). These will be split off from the LLVM project (e.g. to
>   separate Github projects), allowing interested people to continue their
>   development elsewhere.
>
> To relicense LLVM, we will be seeking approval from all of the copyright
holders
> of code in the repository, or potentially remove/rewrite code if we cannot.
> This is a large
> and challenging project which will take a significant amount of time to
> complete.  In the interim, **all contributions to the project will be made
under
> the terms of both the new license and the legacy license scheme** (each of
which
> is described below).  The exception to this is the legacy patent grant,
which
> will not be required for new contributions.
>
> When all of the code in the project has been converted to the new license
or
> removed, we will drop the requirement to contribute under the legacy
license.
> This will achieve the goal of having
> a single standardized license for the entire codebase.
>
> If you are a prior contributor to LLVM and have not done so already, please
do
> *TODO* to allow us to use your code. *Add a link to a separate page here,
which
> is probably a click through web form or something like that.  Details to be
> determined later*.
>
>
> .. _open source licensing terms:
>
> New LLVM Project License Framework
> ----------------------------------
>
> Contributions to LLVM are licensed under the `Apache License, Version 2.0
> <https://www.apache.org/licenses/LICENSE-2.0>`_, with two limited
> exceptions intended to ensure that LLVM is very permissively licensed.
> Collectively, the name of this license is "Apache 2.0 License with
LLVM
> exceptions".  The exceptions read:
>
> ::
>
>    ---- LLVM Exceptions to the Apache 2.0 License ----
>
>    As an exception, if, as a result of your compiling your source code,
portions
>    of this Software are embedded into an Object form of such source code,
you
>    may redistribute such embedded portions in such Object form without
complying
>    with the conditions of Sections 4(a), 4(b) and 4(d) of the License.
>
>    In addition, if you combine or link compiled forms of this Software with
>    software that is licensed under the GPLv2 ("Combined
Software") and if a
>    court of competent jurisdiction determines that the patent provision
(Section
>    3), the indemnity provision (Section 9) or other Section of the License
>    conflicts with the conditions of the GPLv2, you may retroactively and
>    prospectively choose to deem waived or otherwise exclude such Section(s)
of
>    the License, but only in their entirety and only with respect to the
Combined
>    Software.
>
>
> We intend to keep LLVM perpetually open source and available under a
permissive
> license - this fosters the widest adoption of LLVM by
> **allowing commercial products to be derived from LLVM** with few
restrictions
> and without a requirement for making any derived works also open source. 
In
> particular, LLVM's license is not a "copyleft" license like
the GPL.
>
> The "Apache 2.0 License with LLVM exceptions" allows you to:
>
> * freely download and use LLVM (in whole or in part) for personal,
internal, or
>   commercial purposes.
> * include LLVM in packages or distributions you create.
> * combine LLVM with code licensed under every other major open source
>   license (including BSD, MIT, GPLv2, GPLv3...).
> * make changes to LLVM code without being required to contribute it back
>   to the project - contributions are appreciated though!
>
> However, it imposes these limitations on you:
>
> * You must retain the copyright notice if you redistribute LLVM: You cannot
>   strip the copyright headers off or replace them with your own.
> * Binaries that include LLVM must reproduce the copyright notice (e.g. in
an
>   included README file or in an "About" box), unless the LLVM
code was added as
>   a by-product of compilation.  For example, if an LLVM runtime library
like
>   compiler_rt or libc++ was automatically included into your application by
the
>   compiler, you do not need to attribute it.
> * You can't use our names to promote your products (LLVM derived or
not) -
>   though you can make truthful statements about your use of the LLVM code,
>   without implying our sponsorship.
> * There's no warranty on LLVM at all.
>
> We want LLVM code to be widely used, and believe that this provides a model
that
> is great for contributors and users of the project.  For more information
about
> the Apache 2.0 License, please see the `Apache License FAQ
> <http://www.apache.org/foundation/license-faq.html>`_, maintained by
the
> Apache Project.
>
>
> .. note::
>
>    The LLVM Project includes some really old subprojects (dragonegg,
>    llvm-gcc-4.0, and llvm-gcc-4.2), which are licensed under **GPL
>    licenses**.  This code is not actively maintained - it does not even
>    build successfully.  This code is cleanly separated into distinct SVN
>    repositories from the rest of LLVM, and the LICENSE.txt files
specifically
>    indicate that they contain GPL code.  When LLVM transitions from SVN to
Git,
>    we plan to drop these code bases from the new repository structure.
>
>
> .. _patent license:
>
> Patents
> -------
>
> Section 3 of the Apache 2.0 license is a patent grant under which
> contributors of code to the project contribute the rights to use any of
> their patents that would otherwise be infringed by that code contribution
> (protecting uses of that code).  Further, the patent grant is revoked
> from anyone who files a patent lawsuit about code in LLVM - this protects
the
> community by providing a "patent commons" for the code base and
reducing the
> odds of patent lawsuits in general.
>
> The license specifically scopes which patents are included with code
> contributions.  To help explain this, the `Apache License FAQ
> <http://www.apache.org/foundation/license-faq.html>`_ explains this
scope using
> some questions and answers, which we reproduce here for your convenience
(for
> reference, the "ASF" is the Apache Software Foundation, the
guidance still
> holds though)::
>
>    Q1: If I own a patent and contribute to a Work, and, at the time my
>    contribution is included in that Work, none of my patent's claims
are subject
>    to Apache's Grant of Patent License, is there a way any of those
claims would
>    later become subject to the Grant of Patent License solely due to
subsequent
>    contributions by other parties who are not licensees of that patent.
>
>    A1: No.
>
>    Q2: If at any time after my contribution, I am able to license other
patent
>    claims that would have been subject to Apache's Grant of Patent
License if
>    they were licenseable by me at the time of my contribution, do those
other
>    claims become subject to the Grant of Patent License?
>
>    A2: Yes.
>
>    Q3: If I own or control a licensable patent and contribute code to a
specific
>    Apache product, which of my patent claims are subject to Apache's
Grant of
>    Patent License?
>
>    A3:  The only patent claims that are licensed to the ASF are those you
own or
>    have the right to license that read on your contribution or on the
>    combination of your contribution with the specific Apache product to
which
>    you contributed as it existed at the time of your contribution. No
additional
>    patent claims become licensed as a result of subsequent combinations of
your
>    contribution with any other software. Note, however, that licensable
patent
>    claims include those that you acquire in the future, as long as they
read on
>    your original contribution as made at the original time. Once a patent
claim
>    is subject to Apache's Grant of Patent License, it is licensed under
the
>    terms of that Grant to the ASF and to recipients of any software
distributed
>    by the ASF for any Apache software product whatsoever.
>
>
> Legacy License Structure
> ------------------------
>
> .. note::
>    The code base was previously licensed under the Terms described here.
>    We are in the middle of relicensing to a new approach (described above),
but
>    until this effort is complete, the code is also still available under
these
>    terms.  Once we finish the relicensing project, new versions of the code
will
>    not be available under these terms.  However, nothing takes away your
right
>    to use old versions under the licensing terms under which they were
>    originally released.
>
> We intend to keep LLVM perpetually open source and to use a permissive open
> source license.  The code in
> LLVM is available under the `University of Illinois/NCSA Open Source
License
> <http://www.opensource.org/licenses/UoI-NCSA.php>`_, which boils down
to
> this:
>
> * You can freely distribute LLVM.
> * You must retain the copyright notice if you redistribute LLVM.
> * Binaries derived from LLVM must reproduce the copyright notice (e.g. in
an
>   included README file).
> * You can't use our names to promote your LLVM derived products.
> * There's no warranty on LLVM at all.
>
> We believe this fosters the widest adoption of LLVM because it **allows
> commercial products to be derived from LLVM** with few restrictions and
without
> a requirement for making any derived works also open source (i.e.
LLVM's
> license is not a "copyleft" license like the GPL). We suggest
that you read the
> `License <http://www.opensource.org/licenses/UoI-NCSA.php>`_ if
further
> clarification is needed.
>
> In addition to the UIUC license, the runtime library components of LLVM
> (**compiler_rt, libc++, and libclc**) are also licensed under the `MIT
License
> <http://www.opensource.org/licenses/mit-license.php>`_, which does
not contain
> the binary redistribution clause.  As a user of these runtime libraries, it
> means that you can choose to use the code under either license (and thus
don't
> need the binary redistribution clause), and as a contributor to the code
that
> you agree that any contributions to these libraries be licensed under both
> licenses.  We feel that this is important for runtime libraries, because
they
> are implicitly linked into applications and therefore should not subject
those
> applications to the binary redistribution clause. This also means that it
is ok
> to move code from (e.g.)  libc++ to the LLVM core without concern, but that
code
> cannot be moved from the LLVM core to libc++ without the copyright
owner's
> permission.
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi Rafael,

We’ve discussed why a license change is preferable over the span of several
years now.  I’m happy to explain over the phone, contact me off list and we can
talk.

-Chris
> On Aug 10, 2017, at 8:33 AM, Rafael Avila de Espindola <rafael.espindola
at gmail.com> wrote:
> 
> Hi,
> 
> I still don't see any justification in the text why a license change is
> required over having a contributor agreement including whatever patent
> wording we want.
> 
> As such, I don't agree with it.
> 
> Cheers,
> Rafael
> 
> Chris Lattner via llvm-dev <llvm-dev at lists.llvm.org> writes:
> 
>> Hi all,
>> 
>> Now that we’ve settled on the license legalese to get to, we need to
start the process of relicensing.  We’re still sorting through all of the
details of what this will take, but the first step is clear: new contributions
to LLVM will need to be under both the old license structure and the new one
(until the old structure is completely phased out).  From a mechanical
perspective, this is pretty simple, but I want to make sure that the community
is aware of this and has time to digest and discuss any concerns.
>> 
>> In order to spell out what this will look like, we’ve gone ahead and
revised http://llvm.org/docs/DeveloperPolicy.html to reflect what the new
structure will look like.  While the license text is the canonical truth, the
DeveloperPolicy serves a few purposes: it explains to non-lawyers what the
license means, provides rationale for the design, and deals with relicensing
process topics.
>> 
>> I’ve attached a draft of the revised document below.  Please take a
look and let me know if anything should be further clarified or if you have any
other questions and comments.  Thanks!
>> 
>> -Chris
>> 
>> 
>> 
>> 
>> 
>> Copyright, License, and Patents
>> ==============================>> 
>> .. note::
>> 
>>   This section deals with legal matters but does not provide legal
advice.  We
>>   are not lawyers --- please seek legal counsel from a licensed
attorney.
>> 
>> This section addresses the issues of copyright, license and patents for
the LLVM
>> project.  The copyright for the code is held by the contributors of
>> the code.  The code is licensed under permissive `open source licensing
terms`_,
>> namely the Apache 2 license, which includes a copyright and `patent
license`_.
>> When you contribute code to the LLVM project, you license it under
these terms.
>> 
>> If you have questions or comments about these topics, please contact
the
>> `LLVM Developer's Mailing List <mailto:llvm-dev at
lists.llvm.org>`_.  However,
>> please realize that most compiler developers are not lawyers, and
therefore you
>> will not be getting official legal advice.
>> 
>> Copyright
>> ---------
>> 
>> The LLVM project does not collect copyright assignments, which means
that the
>> copyright for the code in the project is held by the respective
contributors.
>> Because you (or your company)
>> retain ownership of the code you contribute, you know it may only be
used under
>> the terms of the open source license you contributed it under: the
license for
>> your contributions cannot be changed in the future without your
approval.
>> 
>> Because the LLVM project does not require copyright assignments,
changing the
>> LLVM license requires tracking down the
>> contributors to LLVM and getting them to agree that a license change is
>> acceptable for their contributions.  We feel that a high burden for
relicensing
>> is good for the project, because contributors do not have to fear that
their
>> code will be used in a way with which they disagree.
>> 
>> Relicensing
>> -----------
>> 
>> The last paragraph notwithstanding, the LLVM Project is in the middle
of a large
>> effort to change licenses, which aims to solve several problems:
>> 
>> * The old licenses made it difficult to move code from (e.g.) the
compiler to
>>  runtime libraries, because runtime libraries used a different license
from the
>>  rest of the compiler.
>> * Some contributions were not submitted to LLVM due to concerns that
>>  the patent grant required by the project was overly broad.
>> * The patent grant was unique to the LLVM Project, not written by a
lawyer, and
>>  was difficult to determine what was protection was provided (if any).
>> 
>> The scope of relicensing is all code that is considered part of the
LLVM
>> project, including the main LLVM repository, runtime libraries
(compiler_rt,
>> OpenMP, etc), Polly, and all other subprojects.  There are a few
exceptions:
>> 
>> * Code imported from other projects (e.g. Google Test, Autoconf, etc)
will
>>  remain as it is.  This code isn't *developed* as part of the LLVM
project, it
>>  is *used* by LLVM.
>> * Some subprojects are impractical or uninteresting to relicense (e.g.
llvm-gcc
>>  and dragonegg). These will be split off from the LLVM project (e.g. to
>>  separate Github projects), allowing interested people to continue
their
>>  development elsewhere.
>> 
>> To relicense LLVM, we will be seeking approval from all of the
copyright holders
>> of code in the repository, or potentially remove/rewrite code if we
cannot.
>> This is a large
>> and challenging project which will take a significant amount of time to
>> complete.  In the interim, **all contributions to the project will be
made under
>> the terms of both the new license and the legacy license scheme** (each
of which
>> is described below).  The exception to this is the legacy patent grant,
which
>> will not be required for new contributions.
>> 
>> When all of the code in the project has been converted to the new
license or
>> removed, we will drop the requirement to contribute under the legacy
license.
>> This will achieve the goal of having
>> a single standardized license for the entire codebase.
>> 
>> If you are a prior contributor to LLVM and have not done so already,
please do
>> *TODO* to allow us to use your code. *Add a link to a separate page
here, which
>> is probably a click through web form or something like that.  Details
to be
>> determined later*.
>> 
>> 
>> .. _open source licensing terms:
>> 
>> New LLVM Project License Framework
>> ----------------------------------
>> 
>> Contributions to LLVM are licensed under the `Apache License, Version
2.0
>> <https://www.apache.org/licenses/LICENSE-2.0>`_, with two limited
>> exceptions intended to ensure that LLVM is very permissively licensed.
>> Collectively, the name of this license is "Apache 2.0 License with
LLVM
>> exceptions".  The exceptions read:
>> 
>> ::
>> 
>>   ---- LLVM Exceptions to the Apache 2.0 License ----
>> 
>>   As an exception, if, as a result of your compiling your source code,
portions
>>   of this Software are embedded into an Object form of such source
code, you
>>   may redistribute such embedded portions in such Object form without
complying
>>   with the conditions of Sections 4(a), 4(b) and 4(d) of the License.
>> 
>>   In addition, if you combine or link compiled forms of this Software
with
>>   software that is licensed under the GPLv2 ("Combined
Software") and if a
>>   court of competent jurisdiction determines that the patent provision
(Section
>>   3), the indemnity provision (Section 9) or other Section of the
License
>>   conflicts with the conditions of the GPLv2, you may retroactively and
>>   prospectively choose to deem waived or otherwise exclude such
Section(s) of
>>   the License, but only in their entirety and only with respect to the
Combined
>>   Software.
>> 
>> 
>> We intend to keep LLVM perpetually open source and available under a
permissive
>> license - this fosters the widest adoption of LLVM by
>> **allowing commercial products to be derived from LLVM** with few
restrictions
>> and without a requirement for making any derived works also open
source.  In
>> particular, LLVM's license is not a "copyleft" license
like the GPL.
>> 
>> The "Apache 2.0 License with LLVM exceptions" allows you to:
>> 
>> * freely download and use LLVM (in whole or in part) for personal,
internal, or
>>  commercial purposes.
>> * include LLVM in packages or distributions you create.
>> * combine LLVM with code licensed under every other major open source
>>  license (including BSD, MIT, GPLv2, GPLv3...).
>> * make changes to LLVM code without being required to contribute it
back
>>  to the project - contributions are appreciated though!
>> 
>> However, it imposes these limitations on you:
>> 
>> * You must retain the copyright notice if you redistribute LLVM: You
cannot
>>  strip the copyright headers off or replace them with your own.
>> * Binaries that include LLVM must reproduce the copyright notice (e.g.
in an
>>  included README file or in an "About" box), unless the LLVM
code was added as
>>  a by-product of compilation.  For example, if an LLVM runtime library
like
>>  compiler_rt or libc++ was automatically included into your application
by the
>>  compiler, you do not need to attribute it.
>> * You can't use our names to promote your products (LLVM derived or
not) -
>>  though you can make truthful statements about your use of the LLVM
code,
>>  without implying our sponsorship.
>> * There's no warranty on LLVM at all.
>> 
>> We want LLVM code to be widely used, and believe that this provides a
model that
>> is great for contributors and users of the project.  For more
information about
>> the Apache 2.0 License, please see the `Apache License FAQ
>> <http://www.apache.org/foundation/license-faq.html>`_, maintained
by the
>> Apache Project.
>> 
>> 
>> .. note::
>> 
>>   The LLVM Project includes some really old subprojects (dragonegg,
>>   llvm-gcc-4.0, and llvm-gcc-4.2), which are licensed under **GPL
>>   licenses**.  This code is not actively maintained - it does not even
>>   build successfully.  This code is cleanly separated into distinct SVN
>>   repositories from the rest of LLVM, and the LICENSE.txt files
specifically
>>   indicate that they contain GPL code.  When LLVM transitions from SVN
to Git,
>>   we plan to drop these code bases from the new repository structure.
>> 
>> 
>> .. _patent license:
>> 
>> Patents
>> -------
>> 
>> Section 3 of the Apache 2.0 license is a patent grant under which
>> contributors of code to the project contribute the rights to use any of
>> their patents that would otherwise be infringed by that code
contribution
>> (protecting uses of that code).  Further, the patent grant is revoked
>> from anyone who files a patent lawsuit about code in LLVM - this
protects the
>> community by providing a "patent commons" for the code base
and reducing the
>> odds of patent lawsuits in general.
>> 
>> The license specifically scopes which patents are included with code
>> contributions.  To help explain this, the `Apache License FAQ
>> <http://www.apache.org/foundation/license-faq.html>`_ explains
this scope using
>> some questions and answers, which we reproduce here for your
convenience (for
>> reference, the "ASF" is the Apache Software Foundation, the
guidance still
>> holds though)::
>> 
>>   Q1: If I own a patent and contribute to a Work, and, at the time my
>>   contribution is included in that Work, none of my patent's claims
are subject
>>   to Apache's Grant of Patent License, is there a way any of those
claims would
>>   later become subject to the Grant of Patent License solely due to
subsequent
>>   contributions by other parties who are not licensees of that patent.
>> 
>>   A1: No.
>> 
>>   Q2: If at any time after my contribution, I am able to license other
patent
>>   claims that would have been subject to Apache's Grant of Patent
License if
>>   they were licenseable by me at the time of my contribution, do those
other
>>   claims become subject to the Grant of Patent License?
>> 
>>   A2: Yes.
>> 
>>   Q3: If I own or control a licensable patent and contribute code to a
specific
>>   Apache product, which of my patent claims are subject to Apache's
Grant of
>>   Patent License?
>> 
>>   A3:  The only patent claims that are licensed to the ASF are those
you own or
>>   have the right to license that read on your contribution or on the
>>   combination of your contribution with the specific Apache product to
which
>>   you contributed as it existed at the time of your contribution. No
additional
>>   patent claims become licensed as a result of subsequent combinations
of your
>>   contribution with any other software. Note, however, that licensable
patent
>>   claims include those that you acquire in the future, as long as they
read on
>>   your original contribution as made at the original time. Once a
patent claim
>>   is subject to Apache's Grant of Patent License, it is licensed
under the
>>   terms of that Grant to the ASF and to recipients of any software
distributed
>>   by the ASF for any Apache software product whatsoever.
>> 
>> 
>> Legacy License Structure
>> ------------------------
>> 
>> .. note::
>>   The code base was previously licensed under the Terms described here.
>>   We are in the middle of relicensing to a new approach (described
above), but
>>   until this effort is complete, the code is also still available under
these
>>   terms.  Once we finish the relicensing project, new versions of the
code will
>>   not be available under these terms.  However, nothing takes away your
right
>>   to use old versions under the licensing terms under which they were
>>   originally released.
>> 
>> We intend to keep LLVM perpetually open source and to use a permissive
open
>> source license.  The code in
>> LLVM is available under the `University of Illinois/NCSA Open Source
License
>> <http://www.opensource.org/licenses/UoI-NCSA.php>`_, which boils
down to
>> this:
>> 
>> * You can freely distribute LLVM.
>> * You must retain the copyright notice if you redistribute LLVM.
>> * Binaries derived from LLVM must reproduce the copyright notice (e.g.
in an
>>  included README file).
>> * You can't use our names to promote your LLVM derived products.
>> * There's no warranty on LLVM at all.
>> 
>> We believe this fosters the widest adoption of LLVM because it **allows
>> commercial products to be derived from LLVM** with few restrictions and
without
>> a requirement for making any derived works also open source (i.e.
LLVM's
>> license is not a "copyleft" license like the GPL). We suggest
that you read the
>> `License <http://www.opensource.org/licenses/UoI-NCSA.php>`_ if
further
>> clarification is needed.
>> 
>> In addition to the UIUC license, the runtime library components of LLVM
>> (**compiler_rt, libc++, and libclc**) are also licensed under the `MIT
License
>> <http://www.opensource.org/licenses/mit-license.php>`_, which
does not contain
>> the binary redistribution clause.  As a user of these runtime
libraries, it
>> means that you can choose to use the code under either license (and
thus don't
>> need the binary redistribution clause), and as a contributor to the
code that
>> you agree that any contributions to these libraries be licensed under
both
>> licenses.  We feel that this is important for runtime libraries,
because they
>> are implicitly linked into applications and therefore should not
subject those
>> applications to the binary redistribution clause. This also means that
it is ok
>> to move code from (e.g.)  libc++ to the LLVM core without concern, but
that code
>> cannot be moved from the LLVM core to libc++ without the copyright
owner's
>> permission.
>> 
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

> On Aug 7, 2017, at 10:53, Chris Lattner via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> * The patent grant was unique to the LLVM Project, not written by a lawyer,
and
>   was difficult to determine what was protection was provided (if any).
Minor nit: "what was protection was" -> "what protection
was".

-- 
Stephen Checkoway