The old Canon film camera EF-M, not to be confused with mirrorless cameras featuring an "EF-M" lens mount, did not have auto focus ability and was manual focus only. Does it support the focus by wire lenses in the EOS line? Does it even have any electrical connectors in the mount (apart from the ones controlling the aperture blades)?
I don't know about the focus-by-wire bit, but this photo.net discussion thread includes side-by-side images of the mounts of a 5D and an EF-M, and shows that the EF-M did indeed have all the electrical contacts of the EOS mount.
My guess would be that manually focusing with focus-by-wire will probably still work, since that's more about electronic communication between the lens's focus motor and the manual focus ring, not about lens-to-body AF communication, which the EF-M lacks.
There are currently 2 types of Canon STM lenses: Fast and silent Lead-Screw Type STM and slow and noisy Gear-Type STM.
The Gear type STM lenses (40mm 2.8 STM and 50mm 1.8 STM) work fine in manual focus with the EF-M, but the Lead screw type lenses (10-18mm STM and 18-135mm STM) will NOT manually focus.
(I also tried the new 18-135mm Nano USM and 70-300mm Nano USM II, and they both also do NOT manually focus on the EF-M)
SO, the EF-M works just fine with the 40mm 2.8 STM and 50mm 1.8 STM lenses, but just as with a DSLR, you do need to half press the shutter to get the metering started before the electronic STM focus will work. It works with the lens set to either AF or MF.
Once it starts working, the AF or MF will continue to work indefinitely, as long as you keep turning the focus ring. This continues even after the cameras metering as stopped. If you stop focusing, the STM will lose power after about 4 seconds of idle time. A half-press tap of the shutter button brings it back to life again.
Image Stabilization is a different story as it does not appear to work at all.
I also tried using my old EF 35-80 Power Zoom lens on the EF-M, and the power zoom function DOES work. But, because this lens has no manual focus ring, the lens of course is not really usable on the EF-M.