I am sure that some companies would spend billions (yes, with a "b") for that. And they already have some of the smartest people on Earth working for them. The

I am sure that some companies would spend billions (yes, with a "b") for that. And they already have some of the smartest people on Earth working for them. The article is more theory than practice. It practice, the big problem is not really about knowing what should be rebuilt. It is about tying the work of many people with different ideas on how thing should be done together. The part about getting the build order correct, which is what the article is about is still important. But that's typically not the reason why everyone hates build systems. People can live with the occasional inefficiency, or "make clean". But getting that binary-only library that is not in the standard location with that source-only other library and its weird versioning scheme, both needing a different version of the same third library, written in a different programming language and using a different packet manager...