Suppose there is an isobaric process whereby the volume of a gas decreases while the pressure of the gas remains constant. Work is done on the gas to compress it.
Since the change in internal energy = Q + W from the first law, there's a +W so the internal energy of the gas should increase.
However, this is inconsistent with Charles law whereby Volume of a gas is proportional to Temperature, since volume has decreased, temperature and hence also internal energy must have decreased.
What am I missing?