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LGPL License and modified source code

  • Good morning everybody,

    I am using Qt 4.6.2 with the LGPL license in a commercial product. For testing this product I used the QtTest module and the QSignalSpy class. The QSignalSpy enforces a Qt::DirectConnectoin which makes a stress test crash (see ).

    So I copied the header file qsignalspy.h and substituted Qt::DirectConnection with Qt::QueuedConnection. This solved the problem. The new header file called just signalspy.h with the class SignalSpy is only used in the unit tests for my product.

    My question is, if I have anything to do to satisfy the LGPL (because of the minor change)? Do I have to provide the modified sourcecode? And if so, to whom?

    Thanks in advance!


  • Moderators

    if you're don't publish your modifications with your product you're not violating the LGPL ... for your personal use you can modify anything you want.

  • Moderators

    Both GPL and LGPL talk about distributing modified sources to users. You don't have to publish them world-wide. And since those are tests, basically you and your co-workers are those users ;)

    In this case, additionally, I think Qt-exception works and you don't need to do anything, just like raven-worx said.

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