[phobos] std.parallelism's unit tests randomly hang on win32

[Walter Bright]

On 5/3/2011 5:43 AM, David Simcha wrote:
>
>> Add asserts on that pointer value going out of range, and keep working 
>> backwards until the point where the value goes wrong is discovered.
>
>
> Been trying to do that, but I think there are multiple places where this is 
> happening and the asserts are affecting codegen or timings just enough to 
> prevent some.

You can also do the simple:

     if (ptr == bad value) *((char*)0)=0;

which doesn't perturb timings or code gen much. I use these often. The debugger 
will tell you which one tripped.