I think this could be fixed by convincing make to consider a missing
   optional dependency as always newer than the target - it may need
   another flavour of optional, but it could be done, and it would fix
   this (because f1.o would always be rebuilt when anything it used to
   depend on has vanished, fixing the dependency information in the
   process).


right... i was thinking that this would be happening.  does it
not with this autodep method?


.mrg.