On Thu, 20 Jan 2000, Jun-ichiro itojun Hagino wrote:

> 	for packages which may break IPv4 part:
> 	- prepare foo and foo6 separately (like apache/apache6)
> 	- on pre-1.4x, foo6 will not be built (BROKEN)
> 	- on post-1.4x, foo6 can be built fine
> 
> 	I'm still wondering how to identify the former case and the latter
> 	case.  Candidates are as follows:
> 	- Check kernel AF_INET6 support - looks unwise.  INET6 can be
> 	  turned off.
> 	- Check existence of certain file - like /usr/include/netinet6/ip6.h
> 	- others?
> 	I think the second option (certain file) is the way to go.  If you have
> 	any other ideas, please let me know.

You could patch the package so that it builds an ipv6 version if gnu
configure finds the header file and sets HAVE_NETINET6_IP6_H
(overridable by a configure option). That way, if the author accepts
the patch, it will build out of the box on NetBSD-1.4.x, NetBSD-1.5,
and maybe other systems, too.