Re: [boost] Valgrind reports use of uninitialized value in any_range

On 16 October 2015 at 07:45, Auer, Jens wrote:

Hi,

I am using an any_range of std::unique_ptr values in one of my programs. When I analyse this with valgrind, it reports many uninitialized value usages in any_range, and I cannot explain this from my code. I managed to produce a small example to reproduce this. I would like to know if that is a real issue, or if can just create a valgrind suppression rule.

It's safe to ignore under all compilers and platforms, under all use-cases, that I have tried. Please see the Boost test matrix to confirm correct functioning. It is due to a sub-optimal implementation that I did for the underlying iterator small buffer optimisation. The any_iterator_buffer uses a boost::array as a target for a placement new. I hope that by updating this code to use aligned_storage that the warning will go away. Since the start of the array is merely used (in the any_iterator implementation) as an argument to placement new I believe the alignment issues are irrelevant unless the type of the value_type is almost 64 bytes and the alignment of the value_type is greater than the alignment of the array. In practice, on the vast majority of platforms / compilers, this doesn't present a real problem. I'm sorry for the confusion my mistake has caused. I need to address this soon.

Best wishes, Jens

PS: I've sent this to boost-users yesterday, but I now think that boost-devel is a better match.

Regards, Neil