Segfault when casting array of Interface types

Franz via Digitalmars-d-learn digitalmars-d-learn at puremagic.com
Mon Sep 15 20:03:15 PDT 2014


On Tuesday, 16 September 2014 at 02:21:42 UTC, 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?)

look at what 's auto has created:

import std.stdio;

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;
   writeln(typeof(i).stringof);
}

Your issue comme from auto.



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