Confusing behavior involving array operations.

[Pillsy]

I have the following program on Mac OS X 10.6.3 running dmd version 2.043:

$ cat if.d
import std.stdio;

void main (string [] args)
{
  foreach(arg; args)
    writeln(arg);

  auto vec = new double[10];

  foreach(i, ref x; vec) { x = cast(double) i; }

  if (args.length > 1 && args[1] == "bar") { vec[] *= 0.5; }
}

This program compiles with no warnings. However, when I run it, I get a bus 
error regardless of the
value of the first command-line argument, or whether it's present at all. I 
also get bus error if I
eliminate the conditional altogether. AFAICT, the array operation I'm doing on 
vec is legitimate
according to

http://www.digitalmars.com/d/2.0/arrays.html

and the fact that the program bombs out regardless of the outcome of the test 
in the conditional is
particularly mystifying.

Any help would be greatly appreciated.

Thanks,
Pillsy