[PATCHv2] Add a warning for invalid function casts

[Bernd Edlinger]

On 11/30/17 16:45, Jason Merrill wrote:
> On Thu, Nov 30, 2017 at 10:14 AM, Bernd Edlinger
> <bernd.edlinger@hotmail.de> wrote:
>> On 11/29/17 22:57, Jason Merrill wrote:
>>> On 10/09/2017 06:30 PM, Bernd Edlinger wrote:
> 
>>>> +  if (INTEGRAL_TYPE_P (t1)
>>>> +      && INTEGRAL_TYPE_P (t2)
>>>> +      && TYPE_PRECISION (t1) == TYPE_PRECISION (t2)
>>>> +      && (TYPE_UNSIGNED (t1) == TYPE_UNSIGNED (t2)
>>>> +      || TYPE_PRECISION (t1) >= TYPE_PRECISION (integer_type_node)))
>>>> +    return true;
>>>
>>> This section needs a comment explaining what you're allowing and why.
>>
>> Okay. I will add a comment here:
>>
>>     /* The signedness of the parameter matters only when an integral
>>        type smaller than int is promoted to int, otherwise only the
>>        precision of the parameter matters.
>>        This check should make sure that the callee does not see
>>        undefined values in argument registers.  */
> 
> If we're thinking about argument promotion, should this use
> type_passed_as rather than assume promotion to int?
> 

I don't know, it is only a heuristic after all, and even if there is no
warning for a bogus type cast that does not mean any
correctness-guarantee at all.

Would type_passed_as make any difference for integral types?


Bernd.