[Boost-users] Swap allocator problem in multi_array.hpp

From: Ewan Campbell (ewancampbell_at_[hidden])
Date: 2004-10-14 11:04:33

When resizing a multi-dimensional array I receive the warning:

d:\microsoft visual studio\vc98\include\xutility(100) : warning C4101: 
'_Tmp' : unreferenced local variable
       d:\boost\include\boost-1_31\boost\multi_array.hpp(246) : see 
reference to function template instantiation 'void __cdecl 
std::swap(class std::allocator<double> &,class std::allocator<double> 
&)' being compiled

An unreference local variable is not exactly the end of the world, but 
it is churned out every time a file is compiled that include this 
function and I'd rather not disable this warning. I can find no mention 
of anyone else having this problem for such a widely used function 
(dynamically resizing arrays).

The specific line that appears to be causing the problem is:
swap(this->allocator_,new_array.allocator_);
in "multi_array.hpp"

I am resizing the array like so

header file:

   typedef boost::multi_array<double, 2> array2d_type;
   typedef array2d_type::index index;

   Class CArrayConfiguration{
   ...
   protected:
   ...
   array2d_type m_pReceiveArray;
   ...
   };

implementation file:

   m_pReceiveArray.resize(boost::extents[M][5]); // where M = 10 -> 1000

and it is this line that prompts the warning.

I am using MSVC++ 6.0 on WinXP.

If I initalising the array to shape and then resize it there is no 
problem, but I require it to be a class member variable.

Thanks in advance,
ec