> Yeah, that's probably be best approach.  It does mean that you can't be
> certain of an application that uses _NETBSD_SOURCE continuing to compile
> correctly on new versions of the system, though.
Thats the price you'll have to pay for change / enhancements ;-)

> A strict POSIX application will define _POSIX_C_SOURCE, and won't define
> _NETBSD_SOURCE (since that's in the implementation's namespace).  Because
> _POSIX_C_SOURCE is defined, <sys/featuretest.h> wouldn't define
> _NETBSD_SOURCE.
>
> For avoidance of doubt, here's what I'd propose putting into
> <sys/featuretest.h>, after the current check for _POSIX_SOURCE:
[..]
Sounds nice. I'll have some cycles left next week. So if nobody else is 
already working on this, then I could provide a patch.

Regards,
Marc

mundus es fabula