Today's compilers. How about the compilers when calloc was first defined? As I said, I've worked on compilers that behaved differently, either always or according to various options. The computing universe has actually become less diverse in some ways than it used to be, so we should be careful of drawing conclusions about old interfaces based on today's monoculture. Is it really impossible for people here to imagine that some of the dozens of platforms that had their own compilers and C libraries chose to do the rounding up in the latter? It would actually be a pretty reasonable choice, for different microarchitectures capable of running the same instruction set and binaries but with different cache subsystems. That way you could make the decision at run time instead of compile time. Many of the early RISC machines did even weirder tricks than that to wring out the last bit of performance on multiple generations without having to recompile.
