casting array literals doesn't work as stated in the docs

[Denis Koroskin]

On Sun, 03 Jan 2010 05:56:21 +0300, Steven Schveighoffer  
<schveiguy at yahoo.com> wrote:

> On Sat, 02 Jan 2010 20:54:30 -0500, Denis Koroskin <2korden at gmail.com>  
> wrote:
>
>> On Sun, 03 Jan 2010 04:23:00 +0300, Trass3r <mrmocool at gmx.de> wrote:
>>
>>> http://www.digitalmars.com/d/2.0/expression.html#ArrayLiteral
>>>
>>> The code example from the docs yields [1 1] and [1 0 1 0] instead of  
>>> [1 1] and [257] for dmd 2.037.
>>>
>>>
>>> Additionally
>>>
>>> short[] t = [cast(short) 5, 3];
>>> short[] t2 = [cast(short) 5, 3].dup;
>>>
>>> void main()
>>> { ...
>>>
>>> yields:
>>>
>>> Error: cannot evaluate _adDupT((& D12TypeInfo_G2i6__initZ),[5,3]) at  
>>> compile-time
>>> Error: cannot implicitly convert expression (_adDupT((&  
>>> D12TypeInfo_G2i6__initZ),[5,3])) of type int[] to short[]
>>> Error: cannot evaluate _adDupT((& D12TypeInfo_G2i6__initZ),[5,3]) at  
>>> compile-time
>>>
>>>
>>> Using int instead of short only removes the second message.
>>>
>>>
>>> Compiler bug(s)?
>>
>> Yes and no. It used to work (and should still work), but the behavior  
>> was changed to take all array literal values into consideration.
>>
>> "Proper" code should look like this:
>>
>> short[] t = [cast(short) 5, cast(short)3];
>>
>> which is err... I'll let someone else to decide. Just imagine there are  
>> ten (or more) values in an array literal.
>
> the cast-entire-array takes care of that.  Corrected docs example:
>
> short[] rt = cast(short[]) (cast(byte[])[1, 1]).dup;
>
> Note the cast of the entire literal, not just the first element.
>
> so now, if you want to set the type of the array, cast the entire  
> array.  If you want to set the type of only one element, cast that one  
> element, but the runtime might decide to use a bigger type anyways.
>
> correcting your code:
>
> short[] t = cast(short[])[5,3];
> short[] t2 = cast(short[])[5,3].dup;
>
> -Steve

Array casting is something I avoid as a plague. It is highly inconsistent:  
in some cases, it does bitwise casting (kind of a reinterpret_cast,  
changing size of an array), in others - in creates per-element copy of an  
array, thus doing at runtime something I'd like to be done at compile-time.

Maybe it's just me, but I wouldn't recommend anyone using array casting  
(other that T[] -> void[]).