[Qt-interest] Licensing

[Constantin Makshin]

On Sunday 30 May 2010 22:46:36 Steven Doerfler wrote:
> If he's right, and there's an ambiguity, then (perhaps) your executable
> may be completely free of restrictions, and you can do anything you like
> with it.  No need to tell people you used Qt, credit Nokia, tell people
> about their rights, or anything.
I've never said you can do whatever you want. I totally agree that you must/should say your program uses Qt (in "About" box, documentation or somewhere else) under the terms of LGPL and give people a way to read full LGPL text ("tell people about their rights", as you said).

> Distributing Qt alone is controlled by section 4.  If you distribute the
> Qt shared libraries on a CD/DVD, you must include Qt source code too. 
> If you let people download Qt shared libraries from your site, your site
> must offer Qt source code too.
Again — the last sentence of section 4 states that "though third parties are not compelled to copy the source along with the object code".
If I create a package with Qt compiled by me from original source code (Qt license files are included into the package and GPL text is shown to the user during installation), am I required to accompany this package with Qt sources?

> Distributing your dynamically linked executable along with the Qt shared
> libraries it depends upon is controlled by section 6.  Since your
> executable is dynamically linked, you're already following section 6b,
> so you just have to say that you used Qt, include its copyright notice
> and a copy of its license, and the various other things required at the
> top of section 6.  You don't have to offer Qt source code in this case.
That's what I was talking about from the very beginning — if you distribute your program along with Qt dynamic libraries compiled from unmodified source code, you don't have to distribute that code. But some people say that you must provide Qt sources with every copy of your program (if it's on a physical media) or let users download them from your server (if the program is distributes through a web site). Then I quoted places of LGPL text which might cause this ambiguity and tried to explain my point of view.

> Steven