It's more than time to rework this section of the manual to document the newer method of handling automatic prerequisite generation.

Then the question becomes, what example can we use to show the power of automated makefile rebuilds?  I think we might need a section in the manual discussing dynamic makefile creation options.  We can start with constructed variable names, then move to included makefile generation, and end up with the most complex: eval.  We'll need to think up a good set of examples to show the various options and when they're appropriate.

in section 4.14 Generating Prerequisites Automatically

the example is quite complex using sed to add the *.d files as target. there are easier ways to do that.

using an extra echo
%.d : %.c
  @echo -n $@" " > $@
  $(CC) $(CFLAGS) -MM $< >> $@

using gcc options -MT and -MF
%.d : %.c
  $(CC) $(CFLAGS) -MM -MT $@ -MT $(basename $@).o -MF $@ $<