compiler cache like functionality

it would be possible to to choose the location of an output artifact based on the hash(es) of the input artifact(s) and transform properties.
this would enable free rebuilds for example when switching back and forth between git branches, stashes, etc.
unlike ccache, this would bypass all i/o activity and thus be potentially much faster.
of course this requires some cache management and dealing with the artifact aliasing, so it's not entirely trivial.