On Wed, Oct 30, 2013 at 7:11 PM, Paul Eggert <egg...@cs.ucla.edu> wrote: > On 10/30/2013 02:24 PM, Jeffrey Walton wrote: >> On Wed, Oct 30, 2013 at 4:01 PM, Paul Eggert <egg...@cs.ucla.edu> wrote: >>> > On 10/30/2013 02:36 AM, Jeffrey Walton wrote: >>> > >>>> >> time_t is supposed to be an integer or real >>>> >> (http://pubs.opengroup.org/onlinepubs/009696699/basedefs/sys/types.h.html). >>> > >>> > Unsigned integers are integers, so an unsigned time_t >> Negative. On all systems, the C standard tells us signed integer >> overflow is undefined and unsigned integer wrap is implementation >> defined (or is it well defined). > > It's well defined to wrap around, for unsigned integer types that are > not narrower than 'int'. But my comment was about POSIX terminology, > not about your terminology, and according to POSIX unsigned integers > are indeed integers. Oh, my bad.
>> > Sure, *sometimes* the warning is useful, just as even a >> > clock that's stopped is right twice a day. But in the code >> > I deal with, the warning is a false alarm more often than >> > not. >> Are you certain of that? > > Sure, and I gave an example. Compile it in an artificial environment > where time_t is unsigned, and TIME_T_MAX is UINT_MAX and TIME_T_MIN > is ((unsigned) 0), and you'll get a warning that's bogus. And there's > no good way to rewrite the code to avoid the warning. >> I'd like to say turn it off for the functions in question (like the >> timt_t example), but I know that can be painful in the free software >> world (we've had the ability for 15 years or so in the MS world). > > We can also do it in the free software world, but it's typically not worth > the maintenance hassle, at least, not for this particular warning, which > is a false alarm way too often. Perhaps I'm approaching this the wrong way (I probably don't have your experience with the platform). When Linux/Unix folks turn off -Wconversion, what do they use to find the bad conversions? Jeff _______________________________________________ Autoconf mailing list Autoconf@gnu.org https://lists.gnu.org/mailman/listinfo/autoconf
