while(!serial) command

In the ds1307 library, theres a while(!serial) command but it seems like a new command exists, while(!serial.available). But it doesn't "convert to bool (boolean)? , according to the error.

The error also says, no match for operator in serial.

Any ideas?

Only the Leonardo needs to wait for the Serial instance to be ready. It uses a different serial to usb chip. while(Serial) and while(Serial.available) or while(Serial.available()) are three different things.