precise gc?

[eskimo]

> 
> I'm not sure I understand why you would hide a pointer from the GC.
As already suggested by Kapps, for weak references. I need that for my
new std.signals implementation.
> 
> > Are there memory models in use
> > where the inverted pointer value might also be in GC memory?
> > 
> 
> Yes, that can happen in 32-bit.
> 
Yeah, you are right if all pointer bits are actually used it is far too
easy. On the other hand especially because less space is wasted for
pointers on 32 bit, I can easily afford an extra variable to solve this
problem (kind of). Buah, I am starting to like 64 bit architectures ;-)

Thanks!