make

[Juergen Wagner]

In article <3019 at chorus.fr> mm at chorus.fr (Marc Maathuis) writes:
>Can anybody explain me why in the following typescript
>'make -n' and 'make' want to recompile:
....
><5>  cat makefile
>prog:   prog.o
>        cc -o prog prog.o
>
>prog.o: x.h
>        cc -c prog.c
>
>x.h:    y.h
>
><6>  > x.h
><7>  > y.h

The problem here is that no matter how often you call 'make', the target
x.h is *ALWAYS* out of date with respect to y.h. Y.h is not being updated.
If there is no such update necessary, I don't see why you would have that
last rule in the Makefile. I'd prefer something like

	foo:	foo.o
		cc -o foo foo.o

	foo.o:	foo.c x.h y.h
		cc -c prog.c

Unless there is a special update for x.h which is necessary if y.h is newer,
the above lines should be sufficient.

Juergen Wagner		   			gandalf at csli.stanford.edu
						 wagner at arisia.xerox.com