Improve reability of GC on win64

[jmh530 via Digitalmars-d]

On Friday, 25 March 2016 at 05:46:04 UTC, Iakh wrote:
> On Thursday, 24 March 2016 at 19:30:46 UTC, Temtaime wrote:
>
>> And what's a problem with unions by the way ? By specs, 
>> currently it's forbidden to have union with pointers and value 
>> types.
>
> It's forbidden in @safe

I actually asked about this in the GSOC GC thread. I was thinking 
you could make the GC more precise in @safe code because of that 
restriction.