>> Then you could pretty safely use gcc -MD etc to generate dependencies 
>> as you build and gather them into .depend (or better allow
>> .include *.d) and completely skip the extra time spent doing depends.
>> 
>> --sjg

>mmmm. You'd be surprised how much time is spent on slow machines (eg. sun3)
>just doing preprocessing. Unifying the depend and compile preprocessing
>would be a tidy gain.

Actually the savings are not insignificant for faster machines too.
Though the dependall stuff already in netbsd's build already eliminates 
extra tree traversals so perhaps not that big a win.  

Being able to tell make to "ignore" stale dependencies would deal with 
the only hiccup - of the build failing when a header or other file 
has been removed/renamed.  Experience at work over the couple of years 
(maybe longer) that we've been using autodep.mk, shows this to be quite
a rare event - maybe once per month or so.

--sjg