{"ast_node_type":"other","tokens":[{"end":40,"kind":"keyword","start":0,"text":"///"}]}
    /// the same underlying `RegionVid`.
    /// convert the same `ty::RePlaceholder(p)` twice, we can map to
    pub(crate) placeholder_index_to_region: IndexVec<PlaceholderIndex, ty::Region<'tcx>>,