Suspicion of regression in uninitialized value detection

[Patrice Bouchand]

Hello,

I suspect a regression in uninitialized value detection, but before
opening a bug I request your advices on the following problem:

I build the following code :
----------------------------------------------------
#include <stdio.h>
#include <stdlib.h>

int main( int argc, char **argv )
   {
   int j;
   int rtn;
   int k,t;

   j = atoi( argv[1] );

   if ( j > 5 )
      {
      rtn = 10;
      }

   k=t;

   printf("rtn = %d\n", rtn);

   exit(0);
   }
----------------------------------------------------

With gcc 4.0:

bash-4.2$ gcc-4.0  -O2 -Wall ./test_gcc2.c -o test_gcc
./test_gcc2.c: In function 'main':
./test_gcc2.c:17: warning: 't' is used uninitialized in this function
./test_gcc2.c:7: warning: 'rtn' may be used uninitialized in this function

With gcc 4.6.1, the warning on rtn disappears :

bash-4.2$  gcc  -O2 -Wall ./test_gcc2.c -o test_gcc
./test_gcc2.c: In function ‘main’:
./test_gcc2.c:8:8: attention : variable ‘k’ set but not used
[-Wunused-but-set-variable]
./test_gcc2.c:17:5: attention : ‘t’ is used uninitialized in this
function [-Wuninitialized]


 Do I need to pass special options to gcc 4.6.1 to enable this
detection or is it a gcc problem ?

   Regards

         Patrice