Array operations, dynamic arrays and length

[via Digitalmars-d-learn]

On Wednesday, 1 July 2015 at 19:09:36 UTC, Alex Parrill wrote:
> I don't think this is a bug.
>
> Since you don't initialize `c` to anything, it defaults to an 
> empty slice. Array [] operations apply to each element of a 
> slice, but `c` doesn't have any elements, so it does nothing.

I _do_ think it's a bug. Compare:

     import std.stdio;

     void main() {
         int[] a = [1,1,1,1];
         int[] b = [1,1,1,1];
         int[] c;
         int[2] d;

         c[] = a[] - b[];  // works
         c.writeln;        // []
         d[] = a[] - b[];  // works
         d.writeln;        // [0, 0]
         d[] = a[];        // throws!
         // object.Error@(0): Array lengths don't match for copy: 
4 != 2
     }

So, in the case of subtraction, it assigns only as many elements 
as the destination has, but for direct assignment, it throws an 
error. This is clearly inconsistent.