Re: [boost] Re: is_pointer Bug

From: Peter Dimov (pdimov_at_[hidden])
Date: 2000-10-21 04:57:24

> >> // Copy
> >> template <typename InputIter, typename ForwardIter>
> >> inline ForwardIter Copy(InputIter first, InputIter last,
ForwardIter
> >result)
> >
> >... and in any event, your InputIter and ForwardIter types can't be
> >cv-qualified anyway, unless you explicitly provide them...
>
> Sure they can. And the compiler agrees with me. This:
>
> int main()
> {
>     int i[10];
>     int j[10];
>
>     int* const p = i;
>     Copy(p, p+10, j);
>
>     return 0;
> }
>
> compiles and generates the optimized assembly.

Yes, it compiles, and instantiates Copy<int *, int *>. Template
parameter deduction strips top level cv-qualifiers. Consider what would
happen if Copy was defined as

template <typename InputIter, typename ForwardIter>
 inline ForwardIter Copy(InputIter first, InputIter last, ForwardIter
result)
{
    for(; first != last; ++first, ++result) *result = *first;
}

and InputIter was int * const. ++first wouldn't compile.

--
Peter Dimov
Multi Media Ltd.