[llvm-dev] RFC: Improving license & patent issues in the LLVM community

[Alex Bradbury via llvm-dev]

On 29 October 2015 at 10:25, Jonas Maebe via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Hi,
>
> Regarding the previously voiced concerns of incompatibilities between the
> Apache and GPLv2 license, I'd like to add one more thing.
>
> I work on a, at this time mostly LLVM-unrelated [1], "GPLv2 or later"
> licensed compiler: the Free Pascal Compiler. Some people in the project are
> vehemently opposed to the GPLv3, so a move of our project to that license
> would not be easy (even if legally perfectly possible).
>
> The reason I care about the LLVM license is that I regularly consult the
> Clang source code to find out things that are not documented anywhere else.
> In particular:
> a) layout details of Objective-C class/category/interface metadata
> b) OS X compilation details, e.g. for which versions of (Mac) OS X and iOS
> do you have to link in which, if any, crt*.o file
>
> Not being able to use the Clang source code anymore as a reference point for
> this kind of information would be a big loss to me. Apple just documenting
> all of this would be equally fine by me, of course, but I don't see that
> happening.

(Disclaimer: I am not a lawyer).

Copyright protects creative expression rather than ideas or facts
(although some jurisdictions do have a copyright-like idea of
'database rights'
https://en.wikipedia.org/wiki/Sui_generis_database_right). Referring
to Clang source to ascertain certain facts wouldn't necessarily put
any requirement on the licensing of the code you later produce.
However for safety many might prefer not to look at the source so that
any incidental similarities can't be accused of being due to copying
code directly. If you're worried about this, asking a community member
to use the Clang source to write a short document on the details you
require might be a way forward.

Alex