Forbid dynamic arrays in boolean evaluation contexts

[Steven Schveighoffer]

On Tue, 26 Mar 2013 13:34:02 -0400, Vladimir Panteleev  
<vladimir at thecybershadow.net> wrote:

> On Tuesday, 26 March 2013 at 17:32:12 UTC, Jonathan M Davis wrote:
>> On Tuesday, March 26, 2013 12:24:56 Vladimir Panteleev wrote:
>>> [] (the literal) has .ptr as null. That may or may not be a bug.
>>
>> As I understand it, it's very much on purpose. It avoids a needless  
>> memory
>> allocation.
>
> In the same way that "" allocates memory?
>
> [] can be an empty slice of *anything*, but it might as well be a  
> 0-length constant in the data segment, similar to "".

"" needs to point to the data segment because it has to point to a  
readable 0 character for C compatibility.  The same is not true for [].

The code for [] is modifiable without changing the compiler, you certainly  
can suggest something different.  I think the function is _d_newarray,  
there may be more than one version (one that is for 0-initialized data,  
one that is not).  Changing it will probably break code that depends on it  
being null (intentionally or not).

But it definitely is NOT a bug.  Any suggested change would be an  
enhancement request.

-Steve