Would like to use Qt, but am having a license-related predicament

schala

Sorry, here's where I read it, at the bottom: http://qt-project.org/doc/qt-5/lgpl.html

@Digia Qt LGPL Exception version 1.1

As a special exception to the GNU Lesser General Public License version 2.1, the object code form of a "work that uses the Library" may incorporate material from a header file that is part of the Library. You may distribute such object code under terms of your choice, provided that the incorporated material (i) does not exceed more than 5% of the total size of the Library; and (ii) is limited to numerical parameters, data structure layouts, accessors, macros, inline functions and templates.@

sierdzio

wow, I did not know about it! You are right, this sounds really scary! Although I have never heard it being used agains anybody, throughout the years.

Header size compared to source size is small. Plus, this says about distributing object files, not executables.

schala

I just hope your earlier interpretation was the right meaning and that Digia/Nokia's lawyers just didn't word it correctly.

sierdzio

I should have given my source: "link":https://qt.gitorious.org/qt/qtbase/source/4cb03924c113c74b99e18c7347278600a011e917:LGPL_EXCEPTION.txt.

This is from a file distributed with all copies of Qt source code. Amazingly, the LGPL license text distributed with Qt does not include the Digia exception you have linked to in your previous post. Which is baffling. Right now I am really confused. I think this is a bug of some sort, maybe in the documentation.

I will ask on the dev mailing list.

schala

I recently had to dig deep for that link I provided as opposed to before.

sierdzio

I've posted the question, you can follow the discussion (if there will be any) here: "link":http://lists.qt-project.org/pipermail/development/2014-June/017396.html.

I will update this thread if anything new springs up.

schala

Appreciated

JKSH

Wow, this is quite a find. I think it is an oversight from the legal/documentation team.

Thank you schala for bringing this up, and thank you sierdzio for researching and escalating this to the dev mailing list.

sierdzio

According to Thiago (maintainer of QtCore), the one that is found in source code should be followed. See the dev mailing list thread.

schala

Yep, I noticed. Thanks again! Been excitedly coding away since reading that.

sierdzio

For the record, I will quote Thiago's answer here:
[quote]An exception cannot restrict the rights. Both expand: both are granting you
the right to distribute binaries that incorporate a certain amount of code
from Qt into the binary. That is necessary due to the nature of inline and
template functions -- most C++-based projects carry an LGPL exception like
that.

In any case, the one in the source code is the valid one.[/quote]

Hope he does not mind. Mailing lists are public anyway. Source: "link":http://lists.qt-project.org/pipermail/development/2014-June/017397.html.