sbp/scalable — comment on commit 01d8d97a6d34b309699d4ad0e64f195219f34776
File: Makefile line 52
By nslater:

Another way to think about it is that a rule is a command saying that the target should be made when its dependancies are updated. An ordered dependency is a fancy way of making sure that a chain of these rules is executed in the right order. A phony target is a one which does not correspond to an actual file, and so should generally never depend on a file. How can a non-file depend on a file? Remember that depend here doesn't mean use, it means that the rule should be run when the dependancies are newer than the target. But if the target isn't a file, that becomes meaningless. Your phony target uses the Makefile, but this isn't a dependency in the language of Make.