c99 goto past initialization

Question

While debugging a crash, I came across this issue in some code:

int func()
{
    char *p1 = malloc(...);
    if (p1 == NULL)
        goto err_exit;

    char         


        

Answer 1

if i compile this code with -O2 flag

gcc -Wall -std=c99 -O2 jump.c

i've got warning:

jump.c: In function ‘func’:
jump.c:10: warning: ‘p2’ may be used uninitialised in this function

and no warning without optimization