inferred size for static array initialization

[Namespace via Digitalmars-d-learn]

On Monday, 2 May 2016 at 20:05:15 UTC, Steven Schveighoffer wrote:
> On 5/2/16 3:38 PM, Namespace wrote:
>>> The assembler might be safe in some instances, but that 
>>> doesn't
>>> reflect the original internal representation in the compiler. 
>>> Some
>>> other configuration of calls may allow the compiler to reuse 
>>> that
>>> memory, and then you run into problems.
>>>
>>> I'm wondering if you used my rewrite if it would actually 
>>> output the
>>> same thing?
>>
>> Not quite. Look for yourself:
>> https://godbolt.org/g/kO8hdW
>> https://godbolt.org/g/KCfYPy
>
> Except for offsets, it looks identical. May be the compiler 
> puts things in different spots for different ways of writing.
>
> But the thing that's not disclosed here is: what happens when 
> the compiler feels the need to reuse that stack space? Your 
> example doesn't have anything that may compete for the space, 
> it just returns after this is over.
>
> For example, define a static array of exactly the same size to 
> use after the call:
>
> int[3] x;
>
> Now, see if x is pigeonholed into that same place your 
> temporary return existed (and therefore 'as' points at it).
>
> I'm still fully on the side of this being unsafe.
>
> -Steve

I used it very often, but always assigned the result to an 
auto-type variable, never to a slice.