Here's a quote I found. Take it for what you think:
Canon FD lenses are manual-focus only lenses which Canon sold in the years before switching over to the autofocus EF system. Many, particularly those made in the late 70s and early 80s, offer excellent optical quality, have smoothly-operating metal barrels and are available quite inexpensively on the used market. So the obvious thought comes to mind - can such lenses be attached to EOS cameras?
Unfortunately the lens mounts used by the two systems are completely incompatible. FD lens mounts are smaller in diameter, have a different lens register from EF lenses, rely on mechanical levers to control lens aperture, are of a breech-lock design (rotating pressure ring) and never contain autofocus motors.* EF lens mounts are larger in diameter, are of a bayonet mount design (put lens into camera and rotate partway to lock), support electronic control of the lens aperture and the lenses usually contain autofocus motors.