[cfe-dev] ConvertArgumentsForCall may segfault when called function has default parameters

[Keno Fischer]

Patch is at http://reviews.llvm.org/D4917.

On Thu, Aug 14, 2014 at 6:40 PM, Reid Kleckner <rnk at google.com> wrote:
> Yes, use cast_or_null. Other AST getters do the same thing.
>
> On Thu, Aug 14, 2014 at 3:34 PM, Keno Fischer <kfischer at college.harvard.edu>
> wrote:
>>
>> So, I believe the seg fault is actually it trying to dyn_cast a NULL
>> expr inside getArg(N). Should I adjust getArg to return NULL in that
>> case?
>>
>> On Thu, Aug 14, 2014 at 6:32 PM, Keno Fischer
>> <kfischer at college.harvard.edu> wrote:
>> > Sounds good, I'll draft up a patch.
>> >
>> > On Thu, Aug 14, 2014 at 6:31 PM, Reid Kleckner <rnk at google.com> wrote:
>> >> I vote for making getLocStart() / getLocEnd() check that getArg(N) is
>> >> not
>> >> null before pulling the location from it. If we have a setter that
>> >> nulls out
>> >> subexprs, then it seems like the class should tolerate null subexprs in
>> >> other methods.
>> >>
>> >>
>> >> On Thu, Aug 14, 2014 at 1:23 PM, Keno Fischer
>> >> <kfischer at college.harvard.edu>
>> >> wrote:
>> >>>
>> >>> Hello,
>> >>>
>> >>> when the CallExpr passed to Sema::ConvertArgumentsForCall has all
>> >>> default parameters, and the number of actual arguments passed is zero,
>> >>> this function will segfault in the call to Call->getLocStart() if the
>> >>> Callee has an invalid getLocStart(), the reason being that since
>> >>> ConvertArgumentsForCall has set the correct number of arguments, but
>> >>> has not filled them in yet, getLocStart() will try to access the first
>> >>> (not yet existent) argument and thus segfaults. One possible fix is to
>> >>> move the call to Call->getLocStart() before the adjustment of the
>> >>> number of function arguments. Does anybody see something better? It
>> >>> seems to me that this shouldn't segfault even on an invalid location,
>> >>> since getLocStart even explicitly checks for the 0 argument case.
>> >>>
>> >>> Thanks,
>> >>> Keno
>> >>> _______________________________________________
>> >>> cfe-dev mailing list
>> >>> cfe-dev at cs.uiuc.edu
>> >>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>> >>
>> >>
>
>