Won't work, it's because there's a thing called "flange distance."
Without getting complicated, it's roughly (or maybe exactly) the distance from the sensor to the lens mount or back of the lens.
If the target camera's flange distance is LESS THAN the flange distance used between the native lens and native camera, you can adapt (usually).
If the target camera's flange distance is MORE, then you normally cannot adapt, at least purely. Sometimes you can get away with either a non-optical adaptation, losing infinity focus, or you have to use an adapter with glass, which usually loses too much quality / light / whatever to really be attractive.
So, while Canon's EOS mount flange distance is less than say Nikon F (which is why you can adapt Nikon lenses to a Canon DSLR), the Leica's is less than Canon, so it cannot be done in a pure sense.
This is also why mirrorless cameras are exciting (since their flange distance is small compared to the cameras of old) -- one can adapt almost any lens to a mirrorless.
This is doubly also why the new Sony A7s are so exciting - finally an affordable, mirrorless, full frame camera -- let the adaptions begin!
Here's a handy chart: