Fantastic build system failure modes and how to fix them (camp2023)

Rebuilding target files when source files have changed is seems easy, but is not. Commonly used build systems (make, ninja, etc.) are often unable to guarantee both that they rebuild only what needs to be rebuilt and that they do not rebuild what does not need to be rebuilt. I will show how to reliably encounter common build system failure modes and explain which architectural choices lead to those. Using DJB's “redo” design as an example, I will show how build system architecture determines if failure modes can be addressed at all. Lastly, I will speculate why many developers dismiss such issues before encountering them – and some even do afterwards. ”Listen Morty, I hate to break it to you, but what people call a build system is just a bunch of rules that compel computers to output garbage. It hits hard, Morty, then it slowly fades, leaving you stranded with a mis-compiled binary. I did it. Your friends are gonna do it. Break the cycle, Morty. Rise above. Focus on build correctness.” about this event: https://pretalx.c3voc.de/camp2023/talk/CFASNP/