RCArray is unsafe

Zach the Mystic via Digitalmars-d digitalmars-d at puremagic.com
Mon Mar 2 17:23:22 PST 2015

On Monday, 2 March 2015 at 20:37:46 UTC, Walter Bright wrote:
> On 3/1/2015 12:51 PM, Michel Fortin wrote:
>> That's actually not enough. You'll have to block access to 
>> global variables too:
>>     S s;
>>     void main() {
>>         s.array = RCArray!T([T()]);   // s.array's refcount is 
>> now 1
>>         foo(s.array[0]);           // pass by ref
>>     }
>>     void foo(ref T t) {
>>         s.array = RCArray!T([]);      // drop the old s.array
>>         t.doSomething();              // oops, t is gone
>>     }

So with Andrei's solution, will s.array ever get freed, since s 
is a global? I guess it *should* never get freed, since s is a 
global and it will always exist as a reference.

Which makes me think about a bigger problem... when you opAssign, 
don't you redirect the variable to a different instance? Won't 
the destructor then destroy *that* instance (or not destroy it, 
since it just got a +1 count) instead of the one most recently 
decremented? How does it hold onto the instance to be destroyed?

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