Make a minimal amount of region APIs public

Author: Xavier Denis

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -1328,14 +1328,20 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         })
     }
 
-    // Evaluate whether `sup_region == sub_region`.
-    fn eval_equal(&self, r1: RegionVid, r2: RegionVid) -> bool {
+    /// Evaluate whether `sup_region == sub_region`.
+    ///
+    /// Panics if called before `solve()` executes,
+    // This is `pub` because it's used by unstable external borrowck data users, see `consumers.rs`.
+    pub fn eval_equal(&self, r1: RegionVid, r2: RegionVid) -> bool {
         self.eval_outlives(r1, r2) && self.eval_outlives(r2, r1)
     }
 
-    // Evaluate whether `sup_region: sub_region`.
+    /// Evaluate whether `sup_region: sub_region`.
+    ///
+    /// Panics if called before `solve()` executes,
+    // This is `pub` because it's used by unstable external borrowck data users, see `consumers.rs`.
     #[instrument(skip(self), level = "debug", ret)]
-    fn eval_outlives(&self, sup_region: RegionVid, sub_region: RegionVid) -> bool {
+    pub fn eval_outlives(&self, sup_region: RegionVid, sub_region: RegionVid) -> bool {
         debug!(
             "sup_region's value = {:?} universal={:?}",
             self.region_value_str(sup_region),
@@ -2248,7 +2254,10 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     }
 
     /// Access to the SCC constraint graph.
-    pub(crate) fn constraint_sccs(&self) -> &Sccs<RegionVid, ConstraintSccIndex> {
+    /// This can be used to quickly under-approximate the regions which are equal to each other
+    /// and their relative orderings.
+    // This is `pub` because it's used by unstable external borrowck data users, see `consumers.rs`.
+    pub fn constraint_sccs(&self) -> &Sccs<RegionVid, ConstraintSccIndex> {
         self.constraint_sccs.as_ref()
     }