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

From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-10-20 07:58:23

Ewan Campbell wrote:
>
> The MSVC++ 6.0 compiler implements swap like so:
>
> template<class _Ty> inline
>    void swap(_Ty& _X, _Ty& _Y)
>    {_Ty _Tmp = _X;
>    _X = _Y, _Y = _Tmp; }
>
> The unreferenced local variable warning is referring to _Tmp. Since
> _Tmp is required to swap the variables, does this not indicate that
> this particular use of the swap function is redundant?

It may be redundant for a specific allocator type, but by commenting the 
swap() line you are eliminating the swap call for all possible allocator 
types, some of which may, indeed, need it.