GCC/GCJ, SWT, and license lock-in

[David Daney]

Steve Perkins wrote:
>    I have a question about using GCC/GCJ to compile a Java application 
> which uses the SWT framework for its GUI, and whether this locks you 
> in or out of any licensing options.  I apologize in advance if this 
> question is somewhat off-topic... I searched "gnu.org" for a mailing 
> list specifically directed toward licensing discussion and came up empty.
>
>    The SWT is covered by the Eclipse Public License (EPL), which does 
> not bind you to use the EPL for programs which merely link to SWT 
> without modifying it (Question #27 at 
> http://www.eclipse.org/legal/eplfaq.php#DERIV).
>    However, the FSF considers the EPL to be incompatible with the 
> GPL.  I'm not sure what impact (if any) this would have on my desire 
> to write a GPL'ed application from scratch, which links to SWT for its 
> GUI.
>    I know that writing a *non*-GPL'ed application, and linking it to 
> GPL'ed code, creates problems (e.g. the Cygwin DLL dependency issue on 
> Windows).  This is because the GPL requires you to use the GPL for 
> works linking to GPL'ed code, even if you aren't modifying that GPL'ed 
> code.  However, it seems that this issue would not arise when going in 
> the other direction... applying the GPL to new code, which links to 
> libraries using non-restrictive licenses.
>    Now, if I were also making modifications to the SWT as part of this 
> work, then the EPL would be imposed upon the whole... and then I would 
> clearly run into a clash between the GPL and EPL.  However, since I am 
> not modifying SWT, the EPL does not require me to impose its terms on 
> the whole... so it appears that I would be free to apply the GPL on my 
> non-derivative new code.  On its face, there doesn't appear to be a 
> licensing problem with applying the GPL to a new application which 
> uses non-modified SWT.
>
>    This seems fairly intuitive to me, but I wanted to bounce it off 
> the GCC community to see if I'm overlooking any potential issues.  For 
> example, I'm not sure if GCC's recent migration from GPL 2 to GPL 3 
> has had any effect of imposing license terms on executables compiled 
> with GCC/GCJ.
I cannot really opine on SWT, but I would encourage you to look at the 
linking exception clauses in GCC's various runtime libraries.  
Specifically classpath/libgcj allow you to link to them with very few 
restrictions.

It might also be a good idea to get a real lawyer to help you evaluate 
your exact situation.

David Daney