Shadow-Pass

This feature would allow the user to render a pass of the shadows in a scene.

There are probably many uses for this, but the specific use I have in mind is for the combination of Cycles with EEVEE. At the moment, Cycles suffers from terminator artifacts. The temporary solution is to use EEVEE. However, EEVEE's shadows have many artifacts. By being able to render a scene in eevee without shadows, and then a shadow pass in cycles, you could combine the strengths of each engine.

Currently the only way (that I know of) to do this is to use shadow catching. The problem, however, is that this doesn't work for self shadowing.

To clarify, this shadow pass would include ONLY the shadows, not the shading (or in simple terms, the "shady side") of objects.