struct ture {
        int a;
};
struct cont {
        struct ture *x;
};

struct ture *x;
struct ture **px;
struct cont *y;
void func (void)
{
        int *a = &(x->a);
        int *b = &x->a;
        int *c = &(y->x->a);
        int *d = &((*px)->a);

        if (x)
                frob();
        if (px)
                frob();
        if (y->x)
                frob();
        if (y)
                frob();

        return;
}
/*
 * check-name: Dereferencing before check
 * check-command: smatch sm_deref_check_deref.c
 *
 * check-output-start
sm_deref_check_deref.c:20 func() warn: variable dereferenced before check 'px' (see line 16)
sm_deref_check_deref.c:24 func() warn: variable dereferenced before check 'y' (see line 15)
 * check-output-end
 */