Fixing const arrays

[Timon Gehr]

On 12/10/2011 11:41 PM, Andrei Alexandrescu wrote:
> 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
>

Yes, but in C++ const is not transitive, so this change necessarily 
introduces some inconsistency. (for the better, I think)

struct S{int* x;}

void foo(T)(T t){ ... }

immutable int x;
foo(immutable(S)(&x)); // deduced type needs to be immutable(S)