Right I understand the nuances - I was simplifying for the sake of brevity.

However, "binary form" isn't the only issue.  You also can't distribute things in source form under a license that further restricts its distribution.  ie - you can't distribute a  libMesh based code under NDA.

The GPL is more onerous than you believe - it's not just about what ends up in your ABI... it's also about what can be considered a "derivative work".  Go look up the discussions about PyQt and GPL.  It's a python library using GPL.  What does GPL mean to python?  I mean, you don't ever distribute a "binary" linked with that python library, right?  However, it has been decided that even though you never "link" to it... any python code "using" PyQt still has to have a GPL license because it's a "derivative work". 

Lots of quotations in that paragraph because I don't quite agree... but the Qt people were upset enough that they created PySide: http://qt-project.org/wiki/PySide  which is a complete reimplementation of PyQt under an LGPL license...

Anyway - we gotta get this stuff out of libMesh... it goes against the general principles I think most of the developers have: that we want to create open source software that can be utilized for both open and closed development...


On Wed, Feb 26, 2014 at 6:55 AM, Roy Stogner <roystgnr@ices.utexas.edu> wrote:

On Wed, 26 Feb 2014, Derek Gaston wrote:

How in the hell did we end up with GPL software in libmesh/contrib?

libHilbert is GPL (says so right in the COPYING file we have for it in contrib).

Linking libMesh to that software in any way is a violation of that license.

No, it's not.  You can link LGPL and GPL software together, you just
have to license the result as GPL, and you basically can't license the
derived work (in this case, "any libMesh library binary built with the
default --enable-libhilbert" or "any binary statically linked to such
a build") as anything else.  But this doesn't preclude also licensing
non-derived works (e.g. "the rest of libMesh's source code", "libMesh
builds with --disable-libHilbert", and probably even
"dynamically-linked apps" thanks to the fact that libHilbert doesn't
make it into user code or our ABIs) under other licences like LGPL.

We should remove libHilbert from libMesh immediately!

Okay, your previous sentence might be wrong, but IMHO this one isn't.

The libHilbert license basically prevents anyone from distributing a
libMesh app plus all dependencies as binaries unless they compiled
libMesh with --disable-libHilbert or they license the whole binary
under the GPL!  I don't think anyone's actually passing around
binaries (we add new features and change the ABI often enough that you
really want to distribute libMesh apps as source code), but the whole
point of us choosing LGPL is that we want to allow people to do this.

How much do we rely on it?

Narrowly but heavily: IIRC libHilbert is basically the only thing
we've got that makes N-to-M restarts possible, which is a very nice
feature to have.