-extern ecdh_t *ecdh_generate_public(void *pubkey);
-extern bool ecdh_compute_shared(ecdh_t *ecdh, const void *pubkey, void *shared);
+extern ecdh_t *ecdh_generate_public(void *pubkey) __attribute__((__malloc__));
+extern bool ecdh_compute_shared(ecdh_t *ecdh, const void *pubkey, void *shared) __attribute__((__warn_unused_result__));