MPL2 instead of LGPL

Roman Gilg subdiff at
Mon Aug 17 16:26:01 BST 2020

On Sun, Aug 16, 2020 at 10:10 AM Roman Gilg <subdiff at> wrote:
> Hi,
> I've read now multiple times about projects replacing their use of
> LGPLv3 [1] with MPL2 [2]. I would be interested in what people in the
> KDE community think about that.
> Examples of such projects are:
> * - LGPL v3 with special
> exception for static linking (why do KDE frameworks not need this?)
> * - was
> GPL2/LGPL3 dual licensed
> The disadvantages of LGPL are to my knowledge:
> * LGPLv3 code not copyable to GPL code. [3]
> * Usage of C++ templates licensed under LGPLv2.1 not possible or grey
> area(?) in proprietary code. [4]

That template weirdness is what worries me the most btw. I want to use
static inheritance in libraries I write more often in the future and
LGPLv3 has a weird and arbitrary "up to 10 lines are allowed" clause
in it.

If one wants to write a modern C++ library that makes heavy use of
templates in the API and which proprietary consumers should be able to
use is this clause alone reason to prefer the MPL2 over the LGPL or is
my concern unfounded?

> * Proprietary code static linking LGPL code is not practically doable.
> [5] See also above ZeroMQ exception.
> Now one would think with KDE Frameworks double-licensed under LGPLv2.2
> and LGPLv3 at least the first and second disadvantages are eliminated.
> But then why did Eigen not make use of this? And what about the static
> linking exception? Is this not relevant to KDE Frameworks? And what
> other important advantages/disadvantages of LGPL in comparison to MPL2
> are there?
> Best
> Roman
> [1]
> [2]
> [3]
> [4]
> [5]

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