Cast a struct to void*

[Ali Çehreli via Digitalmars-d-learn]

On 01/09/2015 10:25 AM, John Colvin wrote:
> struct S
> {
>      void* p;
> }
>
> void main()
> {
>      S s;
>      auto a = cast(void*)s; //Error: e2ir: cannot cast s of type S to
> type void*
> }
>
> Is there are a good reason for this being disallowed?

I know two options:

a)

     alias p this;

b)

     auto opCast(T : void*)()
     {
         return p;
     }

Ali