That doesn't follow. C++ doesn't have a GC to pick up the cycles, not it bakes RC into the language (and in fact, it is not that uncommon to see C++'s project rolling their own RC mechanism).

2015-11-01 11:28 GMT-08:00 Andrei Alexandrescu <andrei@erdani.com>:
On 11/01/2015 02:16 PM, deadal nix wrote:
2015-11-01 6:02 GMT-08:00 Andrei Alexandrescu <andrei@erdani.com
 <mailto:andrei@erdani.com>>:

    On 10/31/2015 11:35 PM, Michel Fortin wrote:

        I think it'd be more important to talk about auto-nulling weak
        references. That's a general concept that is necessary if you want
        reference counting to be useful and safe at the same time.


    Agreed. We need to put weak pointers in the initial DIP and carry
    them through.


It' doesn't looks like this kind of mechanism should be baked into the
language. It come with a cost that maybe one doesn't want to pay. Maybe
one is ok to fallback on the GC on that one. Maybe it is preferable to
provide several kind of RC. Adn weak reference are just one variation
one may wish.

After much deliberation and collective experience, C++ chose to support weak_ptr as a complement to shared_ptr, in spite of the well-understood performance overhead. It is sensible to draw from that experience as well; also, I agree with Michel that safety makes it all the more important that we design weak pointer support in from day one. -- Andrei