Consider the following code which is a simplified version of something I did IRL (and have done a couple of times) where there is an "extra" address-of operator which should not be there.
#define HEAD \ int typestruct my_struct { HEAD;};struct my_struct_extended { HEAD; int a; int b;};int my_function(const struct my_struct *data) { return data->type;}struct my_struct_extended global = { 2, 3, 4 };int main (int argc, char **argv) { struct my_struct_extended *local = &global; // ADDRESS-OF SHOULD NOT BE HERE \/ return my_function((struct my_struct *) &local);}There are to structs, one base struct and one extended struct. An instance of the extended struct is casted to the base struct to be used in my_function(). Due to the misplaced address-of operator however, the function basically starts working on trash data.
The compiler (in my case GCC) always warns when you pass a double pointer to a function expecting single pointer, but when a struct needs to be casted, such an error is masked. I guess the compiler interprets the cast as "YES! I REALLY WANT THIS" or something.
Is there a warning which can be enabled to trap this?
Note: The real-world case is with casts involving struct sockaddr:
ret = rrr_ip_send (&err, ip_data->ip_udp.fd,// EXTRA ADDRESS-OF \/ (struct sockaddr *) &addr, addr_len, (void *) send_data, send_size);