[cfe-dev] static analyzer false positive? (when reinterpreting buffer as char*)

[Sean McBride]

Hi all,

Consider:

----------------
#include <stdint.h>

int main (void)
{
 	uint16_t bar[2] = {0, 0}; // 4 bytes
 	char* foo = (char*)bar;
 	int x = foo[3]; // warning here
  (void)x;
	
	 return 0;
}
----------------

$ clang --version
clang version 3.2 (trunk 164470)

$ clang -Weverything test.c 
(no output)

$ clang --analyze test.c
test.c:7:2: warning: Assigned value is garbage or undefined
        int x = foo[3];
        ^       ~~~~~~
1 warning generated.

I'm not a language lawyer, but isn't this a false positive?  (It is new in Xcode 4.5 vs 4.4.1 and repros in ToT).

Cheers,

-- 
____________________________________________________________
Sean McBride, B. Eng                 sean at rogue-research.com
Rogue Research                        www.rogue-research.com 
Mac Software Developer              Montréal, Québec, Canada