Re: Rethinking the design of xwidgets

[Akira Kyle]

On Tue, Oct 13, 2020 at 10:38 PM, Richard Stallman <rms@gnu.org> 
wrote:

>   > That leads me to my following proposal to rethink the design 
>   > of 
>   > xwidgets. Given that Emacs now has support for dynamic 
>   > modules and 
>   > it is now enabled by default, I propose exposing an 
>   > interface for 
>   > dynamic modules to define custom xwidgets.
>
> I think that is a good idea.  However, before we develop that,
> we should recheck our defenses against nonfree dynamic modules.
> Are they strong enough?

There is the GPL compatibility symbol (plugin_is_GPL_compatible) 
that must be exported in order for Emacs to load a dynamic 
module. I'm not a lawyer but I'd say there's no way someone could 
claim in a court that they weren't willfully violating the GPL if 
they wrote a nonfree dynamic module as they'd have to explicitly 
include such a symbol in their code and it would be literally 
written into the compiled library. I suppose the dynamic module 
documentation and header file (emacs-module.h) could have more 
explicit text explaining the purpose of that symbol and why a 
dynamic module must be GPL compatible. Beyond that, I can't think 
of anything further to protect against nonfree dynamic modules.