Re: [boost] [type_traits][multi_index][msvc-7.1] problems with is_const in VC 7.1

Subject: Re: [boost] [type_traits][multi_index][msvc-7.1] problems with is_const in VC 7.1
From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2015-10-15 16:59:50

On 15/10/2015 20:40, Joaquín M LópezMuñoz wrote:

> Won't you have direct access to a local MSVC 7.1 installation to play
> with prior to commiting any changes to github? The if_ thing in
> particular seems inoffensive enough to try out.

I tried with no luck. It doesn't seem related to is_const, MSVC-7.1 
considers both

const_ref_global_fun_base::operator()(reference_wrapper<Arg>)

overloads exactly equal, even if BOOST_STATIC_ASSERT in that class 
considers both arguments are not the same.

One workaround I've found is to pass one reference_wrapper by const 
reference and the other one by value:

//Note, argument taken by const ref (unchanged)
   Type operator()(
     const reference_wrapper<
       typename remove_reference<Value>::type>& x)const
   {
     return operator()(x.get());
   }

//Note, argument taken by value (changed)
   Type operator()(
     reference_wrapper<
       typename remove_const<
         typename remove_reference<Value>::type>::type> x)const
   {
     return operator()(x.get());
   }

You could make this conditional to MSVC-7.1, but passing 
reference_wrapper by value should lead to the same performance, I guess.

Best,

Ion