Merging Apple's Objective-C 2.0 compiler changes

[Richard Kenner]

> FYI, quoting Brett Smith on this issue (with permission) below.
> 
> When the copyright holder of a program gives you permission to
> "redistribute it and/or modify it under the terms of the GNU General
> Public License as published by the Free Software Foundation, either
> version 2 of the License, or (at your option) any later version," they
> have given you permission to distribute it under the terms of any one or
> more of the licenses specified.

I don't mean to keep this thread alive longer, but that answer is 
not to the question we've been discussing.  OF COURSE you can
"redistribute" a GPLv2-or-later file under GPLv3-or-later.  That's
never been the question!

The question is whether you can RELICENSE a GPLv2-or-later file to
be GPLv3-or-later without needing explicit permission of the copyright
holder.  To understand the difference, note that:

> Also note that just because you receive a work under GPLv2-or-later and
> distribute it under GPLv3-or-later doesn't necessarily mean that the
> previous distributor has new obligations.  For example, if you get some
> GPLv2-or-later source from a distributor that has a tivoized product,
> you can't distribute that source under GPLv3-or-later and then turn
> around and ask the previous distributor for Installation Information.
> They're only on the hook to meet the conditions in one of the licenses
> they chose, which in this case would be GPLv2.