Re: [boost] [dynamic_bitset] bug in to_ulong() in dynamic_bitset.hpp

From: Markus Schöpflin (markus.schoepflin_at_[hidden])
Date: 2007-12-04 04:38:20

Boris Gubenko wrote:

>   A failure of dynamic_bitset library test dyn_bitset_unit_tests3
>   on Tru64/cxx and HP-UX/aCC revealed what appears to be a bug in
>   <boost/dynamic_bitset/dynamic_bitset.hpp> introduced after
>   Boost 1.34.

[Snip long and detailed analysis.]

>   Replacing
> 
>     result |= (m_bits[i] << (bits_per_block * i));
> 
>   with
> 
>     unsigned long piece = m_bits[i];
>     result |= (piece << (bits_per_block * i));
> 
>   on the trunk makes the test succeed: verified on Tru64/cxx and on
>   HP-UX/aCC.

[...]

> 
>   To fix the problem, I suggest to replace the buggy code in
>   <boost/dynamic_bitset/dynamic_bitset.hpp> in the trunk with that
>   in 1.34. If there are no objections, I can do it.

I don't think that any of the authors of dynamic_bitset is still around, so 
there probably won't be any objections. I for one would welcome the fix.

Thanks,
Markus