Many fallthrough switch cases now have the FALLTHROUGH macro to tell the compiler that this is intended.

core/packed_data_container.cpp

@@ -224,7 +224,8 @@ uint32_t PackedDataContainer::_pack(const Variant &p_data, Vector<uint8_t> &tmpd
 
 			string_cache[s] = tmpdata.size();
 
-		}; //fallthrough
+			FALLTHROUGH;
+		};
 		case Variant::NIL:
 		case Variant::BOOL:
 		case Variant::INT: