Why does Clang complain about all my autoreleased objects?

Question

I have the following function:

- (NSString *)urlEncodedValue {
NSString *result = (NSString *)CFURLCreateStringByAddingPercentEscapes(
                   kCFAllocatorDefault, 
                   (CFStringRef)self, 
                   NULL, 
                   CFSTR("?=&+/\r\n"), 
                   kCFStringEncodingUTF8
);

return [result autorelease];

}

Why is Clang giving me the following complaints?

• 1 Call to function 'CFURLCreateStringByAddingPercentEscapes' returns a Core Foundation object with a +1 retain count (owning reference)
• 2 Object sent -autorelease message
• 3 Object returned to caller as an owning reference (single retain count transferred to caller)
• 4 Object over-autoreleased: object was sent -autorelease but the object has zero (locally visible) retain counts

To the best of my knowledge, this conforms to Apple's guidelines regarding memory management and object ownership. Do I have to explicitly release the object? This error has come up 19 times in my project, all under similar circumstances. What am I doing wrong?

Answer 1

I've found the answer to my own question, posting it here if anyone else stumbles across the issue. I was using checker-0.198, checker-0.204 reports no such issue. Seems it was a temporary regression.