I suspect this is similar to another "recent" discussion about passing null pointers to mem* library functions. C89 allowed zero or null. C99 seems to forbid it. I'm going from memory here, can look at standards later if desired On Aug 20, 2015 8:08 AM, "Richard Hipp" <drh at sqlite.org> wrote:
> On 8/20/15, Bernhard Schommer <bernhardschommer at gmail.com> wrote: > > Hi, > > > > the warning which is mentioned in the ticket > > f51d9501800de5a0fb69d5048ce6662981b461ec still occurs also with newer gcc > > versions. The ticket was closed after a gcc bug report was opened. The > gcc > > bug was closed due to a missing testcase. > > I had a quick look at the problem and it seems that the warning is right > > since in certain context and with optimizations enabled gcc can prove > > that EXPR_FULLSIZE > > - nSize == 0 and thus the triggered warning for this is correct. > > I cannot find anything in the memset() documentation that says that > the third parameter must be greater than zero. Am I missing > something? Do there exist implementions of memset() for which that is > so? > > On the other hand, if all conforming implementations of memset() must > work correctly even if their third argument is zero, why is gcc > warning me about this? > > > Replacing > > memset(&zAlloc[nSize], 0, EXPR_FULLSIZE-nSize); > > By > > if(EXPR_FULLSIZE-nSize > 0) > > memset(&zAlloc[nSize], 0, EXPR_FULLSIZE-nSize); > > would remove the warning, > > > > Cheers, > > -Bernhard > > _______________________________________________ > > sqlite-users mailing list > > sqlite-users at mailinglists.sqlite.org > > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > > > > -- > D. Richard Hipp > drh at sqlite.org > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users >
