temporarily allow access to live regions at a given CFG point

Author: lqd

compiler/rustc_borrowck/src/region_infer/values.rs

@@ -176,6 +176,11 @@ impl<N: Idx> LivenessValues<N> {
     pub(crate) fn region_value_str(&self, r: N) -> String {
         region_value_str(self.get_elements(r).map(RegionElement::Location))
     }
+
+    pub(crate) fn live_regions_at(&self, location: Location) -> impl Iterator<Item = N> + '_ {
+        let point = self.elements.point_from_location(location);
+        self.points.rows().filter(move |row| self.points.contains(*row, point))
+    }
 }
 
 /// Maps from `ty::PlaceholderRegion` values that are used in the rest of