Comment by creata
2 days ago
> One of the small but important significances of Rust is that it very often gets to have the same machine code as a correct "in-band error signalling" strategy from C but with source code that the maintainers can actually understand.
But aside from NonZero- and NonNull-based layout optimizations, I don't think Rust is doing anything special to obtain that machine code - it's just relying on LLVM to optimize things.
Well, all of the niche optimisations, so that includes every normal C-style user-defined enumeration because (unlike C or C++) Rust says those aren't just the integers wearing a funny hat.
But sure, for the most part LLVM will do The Right Thing™ here without much help and Rust is just giving better ergonomics to the same backend.