temporarily allow access to regioncx internals

Allow access, from the crate, to:
- SCCs of outlives constraints
- member constraints
- liveness values

Author: lqd

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -58,7 +58,7 @@ pub struct RegionInferenceContext<'tcx> {
     /// regions, these start out empty and steadily grow, though for
     /// each universally quantified region R they start out containing
     /// the entire CFG and `end(R)`.
-    liveness_constraints: LivenessValues<RegionVid>,
+    pub(crate) liveness_constraints: LivenessValues<RegionVid>,
 
     /// The outlives constraints computed by the type-check.
     constraints: Frozen<OutlivesConstraintSet<'tcx>>,
@@ -71,15 +71,15 @@ pub struct RegionInferenceContext<'tcx> {
     /// The SCC computed from `constraints` and the constraint
     /// graph. We have an edge from SCC A to SCC B if `A: B`. Used to
     /// compute the values of each region.
-    constraint_sccs: Rc<Sccs<RegionVid, ConstraintSccIndex>>,
+    pub(crate) constraint_sccs: Rc<Sccs<RegionVid, ConstraintSccIndex>>,
 
     /// Reverse of the SCC constraint graph --  i.e., an edge `A -> B` exists if
     /// `B: A`. This is used to compute the universal regions that are required
     /// to outlive a given SCC. Computed lazily.
     rev_scc_graph: Option<ReverseSccGraph>,
 
     /// The "R0 member of [R1..Rn]" constraints, indexed by SCC.
-    member_constraints: Rc<MemberConstraintSet<'tcx, ConstraintSccIndex>>,
+    pub(crate) member_constraints: Rc<MemberConstraintSet<'tcx, ConstraintSccIndex>>,
 
     /// Records the member constraints that we applied to each scc.
     /// This is useful for error reporting. Once constraint