fn find_best_leaf_obligation<'tcx>(
infcx: &InferCtxt<'tcx>,
obligation: &PredicateObligation<'tcx>,
consider_ambiguities: bool,
) -> PredicateObligation<'tcx>
fn find_best_leaf_obligation<'tcx>(
infcx: &InferCtxt<'tcx>,
obligation: &PredicateObligation<'tcx>,
consider_ambiguities: bool,
) -> PredicateObligation<'tcx>