ISO C became unusable for operating systems development
Ralf Jung has a blog post looking at some of the claims in this paper [0]. Some hopefully representative quotes:> The paper makes many good points, but I think the author is throwing out the baby with the bathwater by concluding that we should entirely get rid of this kind of Undefined Behavior. The point of this blog post is to argue that we do need UB by showing that even some of the most basic optimizations that all compilers perform require this far-reaching notion of Undefined Behavior.> I honestly think trying to write a highly optimizing compiler based on a different interpretation of UB would be a worthwhile experiment. We sorely lack data on how big the performance gain of exploiting UB actually is. However, I strongly doubt that the result would even come close to the most widely used compilers today—and programmers that can accept such a big performance hit would probably not use C to begin with. Certainly, any proposal for requiring compilers to curtail their exploitation of UB must come with evidence that this would even be possible while keeping C a viable language for performance-sensitive code.> To conclude, I fully agree with Yodaiken that C has a problem, and that reliably writing C has become incredibly hard since undefined behavior is so difficult to avoid. It is certainly worth reducing the amount of things that can cause UB in C, and developing practical tools to detect more advanced kinds of UB such as strict aliasing violations.> However, I do not think this problem can be solved with a platform-specific interpretation of UB. That would declare all but the most basic C compilers as non-compliant. We need to find some middle ground that actually permits compilers to meaningfully optimize the code, while also enabling programmers to actually write standards-compliant programs.[0]: https://www.ralfj.de/blog/2021/11/24/ub-necessary.html