RE: [boost] type_traits: workaround bias

From: Yitzhak Sapir (ysapir_at_[hidden])
Date: 2002-03-13 13:32:13

I compiled that with VC6SP5

At that time I was looking at the following, which may explain the
error:

struct X;
template <class T> struct wraps{ struct id {}; };
template <class T> char f(wraps<T&>::id);
int main()
{
    sizeof(f(wraps<X&>::id()));
    return 0;
};

this says:
error C2664: 'f' : cannot convert parameter 1 from 'struct wraps<struct
X &>::id' to 'struct wraps<struct X * &>::id'
        No constructor could take the source type, or constructor
overload resolution was ambiguous

> -----Original Message-----
> From: David Abrahams [mailto:david.abrahams_at_[hidden]]
> Sent: Wednesday, March 13, 2002 8:24 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] type_traits: workaround bias
> 
> 
> Which version of VC are you using?
> I get the ICE with 6sp4.
> It would be pretty damned exciting if we could get this to work...
> 
> -Dave
> 
> ----- Original Message -----
> From: "Aleksey Gurtovoy" <alexy_at_[hidden]>
> 
> 
> > David Abrahams wrote:
> > > > metafunctions, and that doesn't help the compiler. Without
> > > > seeing the code and errors I can't say if that's the case, but
> > > > there is a chance that using something named less
> > > > provocative as a wrapper template can help here.
> > >
> > > Tried that, too :^(
> > >
> > > struct X;
> > > template <class T> struct wraps{};
> > > template <class T> char f(wraps<T&>);
> > > int main()
> > > {
> > >     sizeof(f(wraps<X&>()));
> > >     return 0;
> > > };
> >
> > This compiles:
> >
> > #include "boost/static_assert.hpp"
> >
> > struct X;
> > template <class T> struct wraps{};
> > template <class T> char f(wraps<T&>);
> > template <class T> char(& f(void const volatile*))[2];
> >
> > int main()
> > {
> >     BOOST_STATIC_ASSERT(sizeof(f<X>(wraps<X&>())) == 1);
> >     return 0;
> > }
> >
> >
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> 
> 
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