Re: Deallocating an object twice

["Randy Brukardt" <randy@rrsoftware.com>]

"Victor Porton" <porton@narod.ru> wrote in message 
news:lr11gd$log$2@speranza.aioe.org...
> Victor Porton wrote:
>
>> If I understand correctly, it is an undefined behavior (or is it called
>> unbounded error?) if a pool access is deallocated twice with
>> Unchecked_Deallocation.
>>
>> I think it should be a Program_Error (if checks are on).
>>
>> Why was not this done even in Ada2012 (not speaking about older Ada)?
>>
>> It's bad.
>>
>> Or is it done and I just miss it?
>
> The same should be done if attempt to deallocate an access which never has
> been allocated (for example, if it is an aliased object on the stack).

In both cases, how would you tell? An access type is just a raw pointer. We 
do such a check in Janus/Ada when we can, but it can be reliably detected in 
only a small percentage of cases. (And if the storage pool is user-defined, 
it's up to the storage pool to deal with this -- the language can't do 
anything.)

There's a reason it's called UNCHECKED_Deallocation, after all.

                                         Randy.