Function rustc_mir_transform::dest_prop::places_to_candidate_pair

fn places_to_candidate_pair<'tcx>(
    a: Place<'tcx>,
    b: Place<'tcx>,
    body: &Body<'tcx>,
) -> Option<(Local, Local)>

If the pair of places is being considered for merging, returns the candidate which would be merged in order to accomplish this.

The contract here is in one direction - there is a guarantee that merging the locals that are outputted by this function would result in an assignment between the inputs becoming a self-assignment. However, there is no guarantee that the returned pair is actually suitable for merging - candidate collection must still check this independently.

This output is unique for each unordered pair of input places.