Re: Segfault when casting array of Interface types

[Ali Çehreli via Digitalmars-d-learn]

On 09/15/2014 07:21 PM, rcor wrote:
I'm back for another round of "is this a bug, or am I doing something
stupid?".
C and D implement interface I, and I have an array of each. I'd like to
combine these into one I[], but eventually I'd like to cast an element
back to its original type.

interface I {}
class C : I {}
class D : I {}

void main() {
   C[] c = [new C, new C];
   D[] d = [new D, new D];
   auto i = cast(I[]) c ~ cast(I[]) d;
   assert(cast(C) i[0]); // segfault
}

casting each array to I[] is fine, but casting an element back to C
segfaults (even if it weren't a C, it should just return null, right?)

I don't have an answer and I am not even sure whether this is a bug. 
However, std.conv.to works with the example:

import std.conv;

interface I {}
class C : I {}
class D : I {}

void main() {
  C[] c = [new C, new C];
  D[] d = [new D, new D];

  auto i = c.to!(I[]) ~ d.to!(I[]);    // <-- here
  assert(cast(C)(i[0]));
}

Ali