[cfe-dev] [Patch] Generate a warning if a message is sent to a nil receiver with return type larger than void* (PR 2718)

[Nikita Zhuk]

On 8.4.2009, at 4.42, Ted Kremenek wrote:

> Hi Nikita,
>
> This looks great.  Just to confirm, I think the particular reference  
> to the Apple documentation is the following:
>
> http://developer.apple.com/documentation/MacOSX/Conceptual/universal_binary/universal_binary_tips/universal_binary_tips.html#/ 
> /apple_ref/doc/uid/TP40002217-CH239-CJBJABFC

Yes, that's the correct one.

I have a question related to the nil receiver checks. Would it be  
possible to take the nil receiver assumption (ObjC messages with size  
of return value <= sizeof(void*) sent to nil always return zero) into  
account in GRExprEngine, so that the number of false positives could  
be reduced even further? For example, the following cases generate the  
nil receiver warning, although the conditions of 'if', 'for' and  
'while' statements are always false when the 'obj' is nil (because any  
message sent to nil returns zero).

for(int i = 0; i < [obj intM]; i++)
{
	long long j = [obj longlongM]; // no-warning  (currently generates  
the 'nil receiver' warning)
}

while([obj intM] != 0)
{
	long long j = [obj longlongM]; // no-warning  (currently generates  
the 'nil receiver' warning)
}

if([obj intM] != 0)
{
	long long j = [obj longlongM]; // no-warning  (currently generates  
the 'nil receiver' warning)
}