On Jan 25, 2014, at 8:09 AM, Gary Bilkus <m...@gary.bilkus.com> wrote:
> On 25/01/2014 15:37, John Ralls wrote: >> On Jan 25, 2014, at 5:49 AM, Gary Bilkus <m...@gary.bilkus.com> wrote: >> >>> On 24/01/2014 17:08, Derek Atkins wrote: >>>> John Ralls <jra...@ceridwen.us> writes: >>>> >>>>> if (sizeof(time_t) == 8) >>>>> return (double)((int64)time1 - (int64)time2); >>>>> else >>>>> return (double)((int32)time1 - (int32)time2); >>>> This code probably wouldn't compile cleanly. It would complain about >>>> casting to different sizes. Even though theoretically the compiler >>>> should be able to optimize the branch by noticing that it is always true >>>> or always false, it will still complain about the unused branch. (I >>>> know this from personal experience). >>>> >>>>> That could be done as a macro and inserted into one of the header >>>>> files in each library. >>>>> >>>>> Regards, >>>>> John Ralls >>>> -derek >>>> >>> Given that time_t is always a signed integer value, wouldn't >>> >>> return (double)(time1-time2) >>> >>> just work anyway, at least as far as a patch for mingw is concerned? >> Only if the binary never leaves the machine on which it was compiled. The >> problem arises when the program compiled with one size of time_t is run with >> an msvcrt with the other size. Keith Mashall explains it pretty clearly in >> the second and third emails in that thread I cited a couple of days ago. >> >> Regards, >> John Ralls >> > Hold on though. These solutions don't call MSVCRT at all, so why does that > matter? And if it did, why would your solution work anyway, given that > sizeof is evaluated at compile time? (leaving aside Derek's point that it > might not compile cleanly. > > It seens that trying to find a way of guaranteeing to call the right version > of MSVCRT correctly is way harder than just getting the correct result! Yes, the sizeof() hack was a dumb idea. One normally gets a time_t from an msvcrt function call, so msvcrt is involved regardless. Marshall offers a pretty complex patch with lots of casts, and he certainly knows the ins and outs better than I. Perhaps you should ask him. It looks to me that always defining _USE_32_BIT_TIME_T might work, though you might have to make that conditional on Vista-or-later. Have you tested that? Regards, John Ralls _______________________________________________ gnucash-devel mailing list gnucash-devel@gnucash.org https://lists.gnucash.org/mailman/listinfo/gnucash-devel
