Obscure crashes due to gcc 4.9 -O2 => -fisolate-erroneous-paths-dereference

Jeff Law law@redhat.com
Fri Feb 20 17:32:00 GMT 2015


On 02/20/15 10:09, Florian Weimer wrote:
> On 02/20/2015 06:01 PM, Jeff Law wrote:
>
>> But that's always true -- this isn't any different than aliasing,
>> arithmetic overflow, etc.  The standards define the contract between the
>> compiler/library implementors and the developers.  Once the contract is
>> broken, all bets are off.
>
> What I don't like about this case (std::vector<T>::data() returning
> nullptr vs memcpy/memcmp/qsort non-null assertions) is that it is
> internally non-composing in a totally non-obvious way.  data() is
> explicitly intended to cover interoperability with these older C
> functions, and it fails.
And that's precisely why I consider this class of issues the most 
problematical.

Jeff



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