Segfault when casting array of Interface types

[rcor via Digitalmars-d-learn]

On Tuesday, 16 September 2014 at 08:49:04 UTC, Marc Schütz wrote:
> On Tuesday, 16 September 2014 at 08:39:43 UTC, Marc Schütz 
> wrote:

>
> Whether the compiler should accept that or not is a different 
> question. I guess it should, because if it doesn't, there 
> wouldn't be an easy way to achieve a reinterpret cast (only via 
> an intermediate cast to `void*`, which is clumsy).
>
> Anyway, using `std.conv.to` is the way to go here (if you don't 
> require that last bit of performance), because it is safer in 
> general (also checks for overflows and the like, for example).

Thanks, didn't think of trying std.conv.to. Can someone expand a 
bit on what to! is doing in this situation that cast isn't? I 
looked up 'reinterpret cast' but didn't see the connection to 
this.

>
> AFAIK casting between interfaces and classes needs to adjust 
> the underlying pointer. Therefore, when casting an array, the 
> compiler would have to do that with the entire array, which 
> cannot be copied without allocating memory (and mustn't be 
> modified in-place for consistency reasons). This means that the 
> cast is instead a pure reinterpret cast (repainting).

Is to! creating a new array of pointers while cast isn't? This 
isn't a performance critical section and it's not a huge array, 
so I ask mostly out of curiosity.