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Index: DeveloperPolicy.rst =================================================================== --- DeveloperPolicy.rst (revision 308891) +++ DeveloperPolicy.rst (working copy) @@ -117,8 +117,8 @@ 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: @@ -644,44 +644,226 @@ .. 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 -`_ (with portions dual licensed -under the `MIT License `_, -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. -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. +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. -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. +Relicensing +----------- -.. _LLVM License: +The last paragraph notwithstanding, the LLVM Project is in the middle of a large +effort to change licenses, which aims to solve several problems: -License +* 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 +`_, 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 +`_, 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 ------- -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 +`_ 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`_, which boils down to this: @@ -689,13 +871,13 @@ * 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 `_ if further clarification is needed. @@ -714,33 +896,3 @@ 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. - -We have no plans to change the license of LLVM. If you have questions or -comments about the license, please contact the `LLVM Developer's Mailing -List mailto:llvm-dev@lists.llvm.org`_. - -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. </mailto:board@llvm.org></mailto:llvm-dev@lists.llvm.org></mailto:llvm-dev@lists.llvm.org>