Upcasting slice of class elements

[H. S. Teoh]

On Fri, Jan 05, 2018 at 10:16:04PM +0000, Nordlöw via Digitalmars-d-learn wrote:
> Why isn't
> 
>     class X {}
>     class Y : X {}
>     X[] xs = cast(X[])(Y[].init);
> 
> compilable in safe D?
> 
> What's unsafe about such a cast?

Your original code snippet seems redundant. If you wanted an empty array
of X's, there's no need to cast it from an array of Y's.

Perhaps you had something like this in mind instead?:

	X[] xs = [ cast(X) new Y(...), new Y(...), ... ];

The cast is only needed for the first element; common type inference
takes care of the rest of the array.


T

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