Knowledge of managed memory pointers

[Timon Gehr via Digitalmars-d]

On 04/17/2014 08:55 AM, Manu via Digitalmars-d wrote:
> It occurs to me that a central issue regarding the memory management
> debate, and a major limiting factor with respect to options, is the fact
> that, currently, it's impossible to tell a raw pointer apart from a gc
> pointer.
>
> Is this is a problem worth solving? And would it be as big an enabler to
> address some tricky problems as it seems to be at face value?
>
> What are some options? Without turning to fat pointers or convoluted
> changes in the type system, are there any clever mechanisms that could
> be applied to distinguish managed from unmanaged pointers.

It does not matter if changes to the type system are 'convoluted'. (They 
don't need to be.)

> If an API
> could be provided in druntime, it may be used by GC's, ARC, allocators,
> or systems that operate at the barrier between languages.
>

There already is.

bool isGCPointer(void* ptr){
     import core.memory;
     return !!GC.addrOf(ptr);
}

void main(){
     import std.c.stdlib;
     auto x=cast(int*)malloc(int.sizeof);
     auto y=new int;
     assert(!x.isGCPointer() && y.isGCPointer());
}