[development] Modules that integrate non-GPL PHP apps violate the GPL.

[Karoly Negyesi]

> That alone makes the module a derived work of Drupal.
> 
> But if your program and the other program are linked, even if it is done 
> only at runtime, and make function calls to each other and share data 
> structures, your module is a derivative work of the other program as well.

AAAAAAAAH! Finally somebody explained this whole situation clearly. 

So if I am writing a bridge to run with Drupal that's GPL because of Drupal and because it's considered a derivative of some non-GPL code that means I am breaking some clause in the *other* code licence and we know there is such a clause *because* it is non GPL compatible. So the issue looked cloudy because we know the bridge breaks some rule but it can not be told what without studying the other licence. This makes sense to my obsessed-with-math-logic mind. For the first time, this debacle makes sense even if not a pleasant one.

However, there seems to be an escape! http://forum.joomla.org/index.php?topic=190545.0 this ends with "the LGPL would allow someone else to derive code based on it without any restriction you can make a LGPL bridge to buffer your proprietary extention (such as SMF) to a GPL program."

So, if this holds up then we should allow LGPL code in our repo and ask the bridge module authors to LGPL their code. This is a ton easier than, say, changing the licence of Drupal core.