finding redundant graph entries

[Mervyn Keene, Clubman]

Is there any direct support for showing, or have people come up with clever
ways of finding, unnecessary lines in the DAG? Trivial example: in a
typical HelloWorld build model the "hello" executable depends on hello.o
which in turn depends on hello.c. If there was an explicit direct
dependency of hello.exe on hello.c it would not be incorrect but would be
unnecessary and create fuzziness. It strikes me that an analysis of these
might help find actual bugs in the graph. Does anyone know a way of finding
them? Illustrative sample makefile appended.

hello.exe: hello.o hello.c  # <- redundant
        $(CC) -o $@ $<

hello.o: hello.c
        $(CC) -c $<

.PHONY: clean
clean:
        -rm -f *.exe *.o