It's quite easy to accidentally write makefiles that build something different when you run them a second time, or when some server that used to be reliable sud

It's quite easy to accidentally write makefiles that build something different when you run them a second time, or when some server that used to be reliable suddenly goes down. Or when the user upgrades something that you wouldn't think is related. It does no validation of inputs. So suppose you're bisecting your way towards the cause of a failure related to the compiler version. Ideally there would be a commit which changed the compiler version, so your bisect would find a nice neat boundary in version history where the problem began. Make, by contrast, is just picking up whatever it finds on the PATH and hoping for the best. So the best you can do is exclude the code as the source of the bug and start scratching your head about the environment. That willingness to just pick up whatever it finds and make changes wherever it wants with no regard to whether dependency created by these state changes is made explicit and transparent to the user is what I mean by "imperative".