Relicense {fmt} to make it more friendly for standard library vendors

[vitaut]

According to Billy O'Neal, the standard library vendors (including libstdc++) all can't look at BSD-licensed code. To fix this we need to drop all requirements on binary redistribution, e.g. introduce a clause similar to "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.

See also http://llvm.org/foundation/relicensing/

Also might be a good time to introduce CLA: https://github.com/cla-assistant/cla-assistant

List of current library contributors from blame:

• Victor Zverovich (vitaut)
• Ivan Shynkarenka (chronoxor): Visual Studio 2017: warning C4456: declaration of 'result' hides prev… #1075 (comment)
• Jason Shuo Zang (jasonszang): cmake: default FMT_PKGCONFIG_DIR to a relative path #1078 (comment)
• Daniela Engert (DanielaE): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Elias Kosunen (eliaskosunen): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Jonathan Müller (foonathan): Create PR template to help agree to the licensing terms #1083 (comment)
• Brian Ricciardelli (ricco19, Brian): Forward declare is_string<FILE*> specializations #1086 (comment)
• Michael Winterberg (mwinterb): Added missing typename to FMT_STRING. #1089 (comment)
• Mario Werner (niosHD): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Lars Gullik Bjønnes: Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Olaf Hering (olafhering): install pkg-config file into libdir #1091 (comment)
• Billy Donahue (BillyDonahue): handle fwrite results #1098 #1099 (comment)
• Mark Stapper (starkmapper): Bcc32 compatibility #1079 (comment)
• Lectem: Add compile features for cmake 3.8+ #1103 (comment)
• Alex Alabuzhev (alabuzhev): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• remyabel: Fix a couple of deprecated things. #1102 (comment)
• Bruce Mitchener (waywardmonkeys): Enable [[noreturn]] some. #1107 (comment)
• Dean Moldovan (dean0x7d): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• medithe: Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Alexander Bolz (abolz): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Mathias Winterhalter (ToolsDevler): Restructure printf_arg_formatter to make it customizable #1093 (comment)
• Remotion: Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Tao He (sighingnow): fmt::ptr: support unique_ptr and shared_ptr. #1121 (comment)
• Nicolas (Rakete1111): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Jamboree: Support named arguments #173 (comment)
• Sign Bit / Florin Iucha (0x8000-0000): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• morinmorin: Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Carter Li: Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Denis Blank (Naios): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Paul Dreik (pauldreik): trigger assertion in to_unsigned #1135 (comment)
• denchat: Fix DLL visibility of explicit instantiation "declaration" of internal::basic_data<void> in header format.h and the explicit instantiation "definition" in format.cc #1134 (comment)
• Greg Sjaardema (gsjaardema): Eliminate shadowed variable warnings from gcc-7.2 #1139 (comment)
• Gabi Melman (gabime): Fixed issue #779 #780 (comment)
• Mateusz Janek (stryku): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Michael Lui (mikelui): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Candy Gumdrop: Fix building under NVIDIA's CUDA compiler #875 (comment)
• Ingo van Lil (inguin): Fix warnings #218 (comment)
• jdale88: Fixed some level 4 warnings in VS2013 #28 (comment)
• Thomas Bernard (teajay-fr): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• hhggit: Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Andreas Schönle (AndreasSchoenle): Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)
• Yassine (Ryuuke): added color support for windows #102 (comment)
• tnovotny: Relicense {fmt} to make it more friendly for standard library vendors #1073 (comment)

[mjcaisse]

Boost Software License (BSL) also has no binary requirement.

Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

[DanielaE]

That's fine with me!

[eliaskosunen]

I agree to the changes

[riccozzz]

By the way, I am the artist formerly known as just "Brian" on this list, so you can remove it.

[mwinterb]

As a note, mwinterb and Michael Winterberg are the same. Unless there's another Michael Winterberg out contributing :)

[niosHD]

Hi @vitaut, thank you for the ping in #513. I am fine with changing the license to drop all requirements on binary redistribution.

[LarsGullik]

I agree to the changes.

[alabuzhev]

No objections.

[dean0x7d]

I agree with changing the license!

[medithe]

I agree to the changes!

[abolz]

I agree to the changes.

[Remotion]

I agree to license changes as well.

[Rakete1111]

I agree as well :)

[0x8000-0000]

I agree to the changes.

[morinmorin]

I agree to the changes.

[CarterLi]

That's ok with me.

[Naios]

I agree to the changes.

[stryku]

LGTM, I agree +1

[mikelui]

Late to the party. Agreed!

[nightlark]

Please stay far, far, far away from CLAs -- they are a huge pain that can add significant hurdles to contribution or even make it legally impossible to contribute.

My own experience with this has been with Microsoft/vcpkg; they require signing a CLA in order to open a PR to add a package. I sent the legal department at work an email asking for permission to sign the CLA at the beginning of the year -- it has not been approved because of some "indemnity clause", and they have offered no alternatives for how we can get a package submitted (nearly 6 months later). To be clear, the code for adding a package could legally be open sourced, but because of the CLA it's impossible for me to contribute that change upstream. I've even asked if I could prepare the package and open the PR on my own time so that I could sign the individual CLA instead, and the answer was basically no (submitting the package would be too similar to the project I was getting paid to work on). And this restriction applies no matter how trivial the change is.

Some of the writing on the subject (DCO would be much easier for contributors at companies than a CLA):
https://ben.balter.com/2018/01/02/why-you-probably-shouldnt-add-a-cla-to-your-open-source-project/
https://opensource.com/article/18/3/cla-vs-dco-whats-difference
https://about.gitlab.com/2017/11/01/gitlab-switches-to-dco-license/
https://software.llnl.gov/about/licenses/#developer-certificate-of-origin

Beyond that, an unmodified license that fulfills the requirements you're looking for (Boost as suggested above?) might be easier to get past corporate legal departments than one with exceptions added (ZeroMQ LGPL with static linking exception raised some questions) -- at least as far as upstreaming any changes go. I know where I work legal gives a bit more scrutiny to contributions to OSS projects if their chosen license also covers patents.

[vitaut]

BSD will continue to be an option so exception is not a problem.

[vitaut]

All current contributors to fmt/core.h and format.cc accounted for except for authors of two small commits:

• @Zefz (JohanJansen): 352ae74
• @MikePopoloski: b1d10a2

fmt/format.h:

• @gawain-bolton (Gawain Bolton): 79b79f3

fmt/format-inl.h:

• @vgalka-sl (Vasili Galka): acb469a

fmt/time.h:

• @codicodi: 3f24a38

[teajay-fr]

I have no objections to changing the license terms.

[ghost]

I agree to the changes.

[AndreasSchoenle]

I do of course agree to changing license terms in any way you see fit.

[tnovotny]

I am fine with the changes.

[vitaut]

The new license draft: https://github.com/fmtlib/fmt/blob/master/LICENSE.rst