> I do not understand how this is related to the question. Using
> "BUILD_DEFS+=USE_INET6" did nothing to enforce the IPv6 capability, so
> how does deleting this line change anything?
> 
> If a package unconditionally needs IPv6, then "inet6" is not really
> an option for this package at all, since it should be possible for
> options to be disabled as well as enabled.

I think this is a valid point. We should be very careful with semantics
in order not to make things more confusing than necessary.
In my opinion we need the following functionality:

a) a way for a package to indicate that it can support IPv6
b) a way for a package to indicate that it needs IPv6 support to compile,
i.e. always compiles with IPv6 support.
c) a way for a package to indicate that there is some sort compile time switch
to decide whether to use IPv6 support or not. This is what USE_INET6 if for
so far and which the inet6 option is about to take over.

Of course c) and b) each imply a), but both contain more information than
a). (as a side note, a) does not necessarily mean b) or c) since one could
imagine a case where a package by its own means decides whether to use IPv6
but does not provide a compile time switch for it; not very desirable,
I admit).

My feeling is that it makes little sense to have the switch in c) set per
package. I cannot think why it should make sense on a given system to
decide per package to compile with IPv6 support or not. In contrast, it makes
a lot of sense to have such a global switch, as we used to with USE_INET6.

So much for the specific IPv6 issue.
I would like to take the opportunity to check whether I correctly
understood the various options variables:

PKG_SUPPORTED_OPTIONS: lists the options supported by that package
PKG_OPTIONS_VAR:	name of the options variable for that package
PKG_DEFAULT_OPTIONS:	default settings (with - prefixes to cancel out
a specific option). Is that to be set per package or globally?
Should packages make sure to always use PKG_DEFAULT_OPTIONS+= ?
What is the difference to PKG_SUGGESTED_OPTIONS?

-- 
Georg Schwarz    http://home.pages.de/~schwarz/
 georg.schwarz@freenet.de  +49 178 8545053