On Thursday, July 4, 2019 at 4:53:34 PM UTC+10, Boris Zbarsky wrote: > On 7/4/19 10:11 PM, Gerald Squelart wrote: > > - I found plenty of `unsigned`s around, more than `uint32_t`s. > > How many are in code that predates the ability to use uint32_t, though?
I didn't do deeper archaeology, so it's very possible most unsigneds are in old or 3rd party code. But I didn't want to spend more time on this, in case old-timers already had knowledge about it. ;-) > > - Our latest coding style [1] points at Google's, which has a section about > > Integer Types [3], and the basic gist is: Use plain `int` for "not-too-big" > > numbers > > If you can 100% guarantee that they will not be too big, right? > > (In particular, for generation counters I would be somewhat worried > about making such a guarantee.) They did add "use int64_t for "big" numbers". In my own selfish case, it will be once per profiler start/stop. I'm fairly confident a user won't start and stop the profiler a few billion times in a session. :-D But that was not the point of this discussion, sorry for the distraction. > > never use any unsigned type unless you work with bitfields or need 2^N > > overflow (in particular, don't use unsigned for always-positive numbers, > > use signed and assertions instead). > > Do you happen to know why? Is this due to worries about underflow or > odd behavior on subtraction or something? Details in OP[3]. Some juicy bits: "Because of historical accident, the C++ standard also uses unsigned integers to represent the size of containers - many members of the standards body believe this to be a mistake, but it is effectively impossible to fix at this point." "The fact that unsigned arithmetic doesn't model the behavior of a simple integer, but is instead defined by the standard to model modular arithmetic (wrapping around on overflow/underflow), means that a significant class of bugs cannot be diagnosed by the compiler." "Mixing signedness of integer types is responsible for an equally large class of problems." > -Boris g. _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
