Suspicion of regression in uninitialized value detection

[Patrice B]

Sorry for the noise, the problem is already tracked here:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18501

Le 2 décembre 2011 10:42, Patrice Bouchand <pbfwdlist@gmail.com> a écrit :
> Hello,
>
> I suspect a regression in uninitialized value detection, but before opening
> a bug I request your advices on the following problem:
>
> I compile 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
>