Array operations

[Andy Valencia via Digitalmars-d-learn]

In the following code, two questions.  First, is there any 
difference between "x[] = y" and "x[] = y[]"?  It appears not.  
Second, in assigning from arrays of differing sizes, Phobos 
causes an illegal instruction, rather than the sort of exception 
I'd have expected.  I'm curious why they stepped away from D's 
exception architecture?

Thanks!
Andy
```d
import std.stdio : writeln;

void main() {
    int[] x = new int[8];
    x[] = 1;
    int[] y = new int[4];
    y[] = 2;
    x[0 .. 4] = y;
    writeln(x);
    x[] = 1;
    x[0 .. 4] = y[];
    writeln(x);
    x[] = y[];
    writeln(x);
}
```