Third party "digital" lenses are not the same thing as EF-S lenses, if you want to butcher the safety stops then some EF-S lenses can be used to take
crap heavily vignetted images on a ff camera with the risk of severe damage to that camera, hardly seems worth the effort.
I do remember back in the day people did experiment with the practicality of various EF-S lenses on EF mounts, mainly so they could use EF-S lenses on the 10D as that predated EF-S and was EF only.
The Tokina (Third-party "digital") 11-16mm f/2.8 lens is in fact designed for crop lenses, and is so marketed; yet its construction does allow it to be used, without vignetting, at 16mm, on FF cameras. I like it because I can use it on both my 6- and 7D bodies, with very satisfactory results. I tried this after learning about it on this and many other forums...
Technically speaking, only lenses with an EF-S mount are EF-S lenses. Which means all third party lens with an image circle only designed to cover an APS-C sensor are in fact EF lens.
The EF-S lenses features an extra bit of plastic at the rear which prevents mounting the lens to any EF mount bodies. EF-S mount bodies have a corresponding extra cut out in the mount, enabling the body to take both EF and EF-S lenses.
Unlike Nikon FX, DX and all Canon mount EF lenses which must be designed to clear a FF mirror, EF-S mount lenses can make use of the extra room left over by the smaller mirror in APS-C bodies, so the rear elements can poke into the body a bit more. This allows some room for manoeuvre on how extreme the retrofocus designs have to be on EF-S lenses.
Pulling out the plastic cover at the rear of a EF-S lens such as the 10-22 does allow it to mount to a FF body, and you can look through the heavily vignetted viewfinder at 10mm - but when the mirror moves, it won't clear the back of the lens until its zoomed in to about 13mm. Incidentally, if you remove the filter the 10-22 fills the frame from 13mm onwards. But I wouldn't recommend trying - even if you stop it down fully, the corners are beyond mush.