I wonder if the headers clause of the GPL would apply here.

3. Object Code Incorporating Material from Library Header Files.

The object code form of an Application may incorporate material from a
header file that is part of the Library. You may convey such object
code under terms of your choice, provided that, if the incorporated
material is not limited to numerical parameters, data structure
layouts and accessors, or small macros, inline functions and templates
(ten or fewer lines in length), you do both of the following:

    * a) Give prominent notice with each copy of the object code that
the Library is used in it and that the Library and its use are covered
by this License.
    * b) Accompany the object code with a copy of the GNU GPL and this
license document.


On Thu, Nov 4, 2010 at 12:54 PM, Mrinal Kalakrishnan <mail@mrinal.net> wrote:
> Hi,
>
> Does anyone know the implications of a GPL-licensed .msg or .srv file?
> If I wrote code that uses these messages (through the generated C++
> code), does my code also need to be under the GPL? Or maybe, because
> the code generation process only reads the GPL-encumbered .msg file
> and outputs independent C++ code it's somehow free of the license?
>
> Thanks,
> Mrinal
> _______________________________________________
> ros-users mailing list
> ros-users@code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
>