GNU License warning:

[Kagamin via Digitalmars-d]

On Friday, 13 January 2017 at 02:25:03 UTC, Ignacious wrote:
> Licenses should be more specific in their terminology and their 
> behaviors and effects rather than using arbitrary divisions.

If your plugin uses contrived API riddled with all good C(++) 
misfeatures to customize like 80% of program's functionality - it 
thus creates a competing proprietary product, which is what GPL 
tries to prevent. AFAIK it doesn't allow you to use complex API 
with out of process plugins either. With this division of API GPL 
tries to control what a plugin can do to the host application, 
namely it tries to keep degree of integration and complexity of 
the plugin API low. If you know a better way to do it, you can 
propose it to FSF, that's also why GPL addresses automatic 
license upgrade.