If the alternative is putting gas in a bucket, which a) will be evaporating into your face while you walk back; b) will be dissolving the bucket while you walk

If the alternative is putting gas in a bucket, which a) will be evaporating into your face while you walk back; b) will be dissolving the bucket while you walk back; c) you won't be able to use the get the gas into the tank anyway, even if it hasn't completely dissolved the bucket, then yes you walk. That's what happens when you run out of gas and you don't have a container in your car. You walk.