Re: Add GPL compatibility check for plugins

[kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)]

> I was not thrilled with this change.  But the FSF was very insistent.
> The way I figured it, plugins already must be GPL-compatible to work
> with GCC.  Whether they need to actively declare it or not makes no
> difference, so it didn't really matter to me one way or the other.

Here's how I see the legal issue.  There's no difference between a
plugin and linked-in code in terms of whether that code is a
derivative work of GCC: it is if you're using GCC's data structures.

There's no prohibition against *creating* a mix of proprietary code
with code covered by the GPL and, again, this would apply to code
linked in to GCC or within a plugin.  The prohibition is against
*distributing* such code.  If you have code that's derived from both
GPL code and code with an non-GPL compatible license, there is no
license that allows distribution of that work, so it cannot be
redistributed.  So I don't see how you can have a "proprietary plugin"
and I think that reminding people of that fact is a good idea.

(The Linux driver issue isn't quite as clear: it's not as clear to me that
a Linux device driver would be viewed as a derived work of the kernel.  But
of course none of this has ever been litigated and I think we should hope
that it never is.)