[cfe-dev] Why the argument of `delete' is converted to void* ?

[John McCall]

On Jul 8, 2012, at 10:46 AM, Enea Zaffanella wrote:
> On 07/05/2012 11:53 PM, John McCall wrote:
>> On Jul 4, 2012, at 10:13 AM, Enea Zaffanella wrote:
>>> On 07/04/2012 05:07 PM, Jean-Daniel Dupas wrote:
>>>> Le 4 juil. 2012 à 15:57, Enea Zaffanella a écrit :
>>> [...]
>>>>> Sorry for the misunderstanding, but the original question was not
>>>>> really meant to be restricted to classes having a trivial destructor
>>>>> (if you add a non-trivial destructor to class S then "delete ps" will
>>>>> call it, whereas "operator delete(ps)" will not).
>>>>> 
>>>>> To rephrase my question: since in the general case "delete ps" may
>>>>> also call the destructor, why is its argument (always) converted to void*?
>>>>> 
>>>>> Cheers,
>>>>> Enea.
>>>> 
>>>> 
>>>> AFAIK, even with a non trivial destructor, the code always end up
>>>> calling the operator delete(void *) to free the memory.
>>> 
>>> Yes, the argument of "operator delete" has to be converted to a void*.
>>> 
>>> But this, afaict, is an inner implementation detail that should not be
>>> exposed in the AST (or it should be exposed elsewhere, e.g., in a method
>>> named getOperatorDeleteArg).
>>> 
>>> The argument of the CXXDeleteExpr is *not* subject to such an implicit
>>> conversion; as a matter of fact, the implicit conversion (if made
>>> explicit by the user) would change the semantics of the delete
>>> expression by killing the call of the destructor.
>> 
>> It's a bug in the AST;  Sema is doing an implicit conversion to void* in order
>> to not have to implement custom logic for deleting values of record type, but
>> it should at least be dropping the extra ICE when it does so.  IR-generation
>> has to awkwardly work around this.
>> 
>> John.
> 
> Can you please review the attached patch?
> (It passes all tests in clang.)

How odd.  This was done intentionally?

Anyway, approved.

John.