On 19.2.2016 13:08, Marek Polacek wrote: > On Fri, Feb 19, 2016 at 01:04:04PM +0100, Petr Spacek wrote: >> On 19.2.2016 08:50, Jakub Jelinek wrote: >>> On Fri, Feb 19, 2016 at 03:12:29AM +0100, Kevin Kofler wrote: >>>> Jakub Jelinek wrote: >>>>> ASSERT(this) is pointless, it is testing if undefined behavior didn't >>>>> happen after the fact, that is just too late. As I said, use >>>>> -fsanitize=undefined to make sure you don't call methods on nullptr. >>>> >>>> Doesn't -fno-delete-null-pointer-checks make such ASSERTs work (and also >>>> explicit "if (this)" type checks)? I read that that flag fixes programs >>>> which rely on "if (this)" checks. >>> >>> That switch allows to work around buggy programs, at the cost of optimizing >>> them less, yes. In any case, such programs should be fixed, this must be >>> always non-NULL, methods can't be called on NULL pointers. >> >> Could you elaborate on this, please? >> >> What is wrong with >> if (ptr != NULL) >> ? >> >> What standard says that it is wrong? > > It's about checking whether "this", in C++, is NULL. Since any call on a null > pointer is undefined behavior, any code relying on such checks is > non-standard.
Ah, okay. I was talking about pure C all the time, so I got confused :-) -- Petr Spacek @ Red Hat -- devel mailing list devel@lists.fedoraproject.org http://lists.fedoraproject.org/admin/lists/devel@lists.fedoraproject.org
