make dependency rules inadequate - (nf)

[utzoo!decvax!pur-ee!uiucdcs!essick]

#R:uiucdcs:8000001:uiucdcs:8000002:000:837
uiucdcs!essick    Jul 23 11:02:00 1982

	Oh well, it appears that I was wrong and that if I had used my
head things would have been more obvious. I figured that since the
a.c file is where the `#include "a.h"` is, then a.c should be dependent
on a.h.  Boy was I wrong.  I had thought that the dependencies should
look like:

	all -> a.o -> a.c -> a.h

when in fact they should look like:

	all -> a.o +-> a.c
	           !
	           +-> a.h

Thanks for all the responses straightening me out.

Just for the book: the first dependency tree has the following fault:
Suppose that a.h is modified and, using my suggestion of passing 
modification status back up the tree, we decided to recompile a.c into
a.o.. Well, a.c still hasn't been touched, so the next time, things
will be recompiled because a.h has a more recent modification date than
a.c.

	Ray Essick
	uiucdcs!essick