initialization of 'void (*)(void *, oid_t *, const void *, void *)' {aka 'void (*)(void *, struct _oid_t *, const void *, void *)'} from incompatible pointer type 'int (*)(void *, oid_t *, const void *, void *)' {aka 'int (*)(void *, struct _oid_t *, const void *, void *)'} [-Wincompatible-pointer-types]