Install new LLVM license structure and new developer policy.

This installs the new developer policy and moves all of the license
files across all LLVM projects in the monorepo to the new license
structure. The remaining projects will be moved independently.

Note that I've left odd formatting and other idiosyncracies of the
legacy license structure text alone to make the diff easier to read.
Critically, note that we do not in any case *remove* the old license
notice or terms, as that remains necessary until we finish the
relicensing process.

I've updated a few license files that refer to the LLVM license to
instead simply refer generically to whatever license the LLVM project is
under, basically trying to minimize confusion.

This is really the culmination of so many people. Chris led the
community discussions, drafted the policy update and organized the
multi-year string of meeting between lawyers across the community to
figure out the strategy. Numerous lawyers at companies in the community
spent their time figuring out initial answers, and then the Foundation's
lawyer Heather Meeker has done *so* much to help refine and get us ready
here. I could keep going on, but I just want to make sure everyone
realizes what a huge community effort this has been from the begining.

Differential Revision: https://reviews.llvm.org/D56897

llvm-svn: 351631

1 files changed, 212 insertions, 57 deletions

diff --git a/llvm/docs/DeveloperPolicy.rst b/llvm/docs/DeveloperPolicy.rst
index 09912940cde..daebe9e2eac 100644
--- a/llvm/docs/DeveloperPolicy.rst
+++ b/llvm/docs/DeveloperPolicy.rst
@@ -113,8 +113,8 @@ a file inline, making it difficult to work with for reviewers using that
 program.
 
 When submitting patches, please do not add confidentiality or non-disclosure
-notices to the patches themselves.  These notices conflict with the `LLVM
-License`_ and may result in your contribution being excluded.
+notices to the patches themselves.  These notices conflict with the LLVM
+licensing terms and may result in your contribution being excluded.
 
 .. _code review:
 
@@ -646,44 +646,226 @@ 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 an attorney.
+   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 individual contributors of
-the code and the terms of its license to LLVM users and developers is the
-`University of Illinois/NCSA Open Source License
-<http://www.opensource.org/licenses/UoI-NCSA.php>`_ (with portions dual licensed
-under the `MIT License <http://www.opensource.org/licenses/mit-license.php>`_,
-see below).  As contributor to the LLVM project, you agree to allow any
-contributions to the project to licensed under these terms.
+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@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 require copyright assignments, which means that the
-copyright for the code in the project is held by its respective contributors who
-have each agreed to release their contributed code under the terms of the `LLVM
-License`_.
+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::
 
-An implication of this is that the LLVM license is unlikely to ever change:
-changing it would require tracking down all the contributors to LLVM and getting
-them to agree that a license change is acceptable for their contribution.  Since
-there are no plans to change the license, this is not a cause for concern.
+   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.
 
-As a contributor to the project, this means that you (or your company) retain
-ownership of the code you contribute, that it cannot be used in a way that
-contradicts the license (which is a liberal BSD-style license), and that the
-license for your contributions won't change without your approval in the
-future.
 
-.. _LLVM License:
+.. _patent license:
 
-License
+Patents
 -------
 
-We intend to keep LLVM perpetually open source and to use a liberal open source
-license. **As a contributor to the project, you agree that any contributions be
-licensed under the terms of the corresponding subproject.** All of the code in
+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:
@@ -691,13 +873,13 @@ 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).
+  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
+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.
@@ -715,30 +897,3 @@ 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.
-
-Note that the LLVM Project does distribute dragonegg, **which is
-GPL.** This means that anything "linked" into dragonegg must itself be compatible
-with the GPL, and must be releasable under the terms of the GPL.  This implies
-that **any code linked into dragonegg and distributed to others may be subject to
-the viral aspects of the GPL** (for example, a proprietary code generator linked
-into dragonegg must be made available under the GPL).  This is not a problem for
-code already distributed under a more liberal license (like the UIUC license),
-and GPL-containing subprojects are kept in separate SVN repositories whose
-LICENSE.txt files specifically indicate that they contain GPL code.
-
-Patents
--------
-
-To the best of our knowledge, LLVM does not infringe on any patents (we have
-actually removed code from LLVM in the past that was found to infringe).  Having
-code in LLVM that infringes on patents would violate an important goal of the
-project by making it hard or impossible to reuse the code for arbitrary purposes
-(including commercial use).
-
-When contributing code, we expect contributors to notify us of any potential for
-patent-related trouble with their changes (including from third parties).  If
-you or your employer own the rights to a patent and would like to contribute
-code to LLVM that relies on it, we require that the copyright owner sign an
-agreement that allows any other user of LLVM to freely use your patent.  Please
-contact the `LLVM Foundation Board of Directors <mailto:board@llvm.org>`_ for more
-details.