[ITK-dev] Bug in the library, or just in the test..?

[Johnson, Hans J]

This is not a bug in std::fill_n

The bug is “&this->m_Data[0]”.

I think that we need to check for this degenerate case.

I pushed an initial patch to review:  http://review.source.kitware.com/#/c/20307/

Hans




On 10/23/15, 12:33 PM, "Insight-developers on behalf of Luc Hermitte" <insight-developers-bounces at itk.org on behalf of luc.hermitte at c-s.fr> wrote:

>Hi,
>
>Le 23/10/2015 18:43, David Cole via Insight-developers a écrit :
>> The itkTransformTest is the only test failing on my Visual Studio 2013
>> Debug dashboard because of this code:
>
>What is the exact error produced when your run the test in verbose mode?
>
>
>> The problem is in the Fill implementation:
>>
>>     template< typename TValue >
>>     void VariableLengthVector< TValue >
>>     ::Fill(TValue const & v) ITK_NOEXCEPT
>>     {
>>       std::fill_n(&this->m_Data[0], m_NumElements, v);
>>     }
>>
>> In this test call, m_Data is nullptr, and m_NumElements is 0, so
>> clearly,&m_Data[0] is not a useful pointer, and with 0 elements, there
>> is nothing to fill.
>>
>> So.... should the implementation of Fill be changed to be conditional
>> on the pointer being non-nullptr, or the number of elements being
>> non-zero, or both? (Are other Fill implementations protected like so?)
>>
>> Or should the test be changed to avoid calling Fill when there are no
>> elements...?
>
>I'd say that this is a bug in std::fill_n (or something related to the
>STL being in CHECKED MODE) and that we should fall back into a plain
>loop. We should avoid adding such defensive tests (if (!empty) fill_n()).
>
>I can take care of this issue (only on Monday). If you don't mind, I'd
>rather avoid rebasing yet another time and first go through
>http://review.source.kitware.com/#/c/20253/10 (I could also fix the
>issue I've introduced in my first patch on VLV in this patch, but this
>is not the usual patching policy if I understand correctly)
>
>
>Regards,
>--
>Luc Hermitte
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