why is this cast required?

[DanielG]

```d
alias IntFunc = int delegate();

void exec(IntFunc[] funcs) {}

void main()
{
	int two() => 2;

	exec(
		// why do I have to cast to the exact type that exec() already 
takes?
		cast(IntFunc[])
		[
			() => 1,
			() => two(),
		]);
}
```

Without the cast, the error is:

>Error: incompatible types for `(() => 1) : (() => two())`: `int 
>function() pure nothrow @nogc @safe` and `int delegate() pure 
>nothrow @nogc @safe`