[Issue 24772] Casting class references to void* should be @safe

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24772

--- Comment #7 from Richard (Rikki) Andrew Cattermole <alphaglosined at gmail.com> ---
That does establish some casting should be valid.

I.e.

```d
import std.stdio;

void main() {
    writeln(cast(size_t)cast(void*)new Object);
}
```

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