Fixing const arrays

[kenji hara]

2011/12/11 Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org>:
> On 12/10/11 4:31 PM, kenji hara wrote:
>>
>> Treating whole constant arrays as ranges by automatically shedding the
>> top-level const is good.
>> But realizing it by language semantic change is definitely bad.It
>> breaks IFTI rule, and adding special case will make difficult to learn
>> language.
>>
>> Instead of language change, we can add specializations that receive
>> non-ranges and convert them to ranges by removing top-level const.
>> I believe that it is Phobos issue and is never the issue of language.
>
>
> I should add there is precedent. C++ also removes top-level const when
> passing objects by value to templates. Deducing top-level const with
> pass-by-value is inherently nonsensical.
>
> Andrei
>

Hmm, it's for sure.
----
void print_type(int){}

template <typename T>
void f(T p)
{
    int n;
    p = &n;     // OK, head is mutable
    //*p = 10;  // NG, tail is const
    print_type(p);
                // Error: need explicit cast from int const * to int
                // T is deduced as int const * == top const is removed
}
int main()
{
    int n;
    int const * const p = &n;
    f(p);
    return 0;
}

Kenji