debug

Author: lcnr

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -72,10 +72,6 @@ pub(crate) fn handle_opaque_type_uses<'tcx>(
     for (external_name, variable) in
         universal_region_relations.universal_regions.named_universal_regions_iter()
     {
-        debug!(
-            "init_free_and_bound_regions: region {:?} has external name {:?}",
-            variable, external_name
-        );
         definitions[variable].external_name = Some(external_name);
     }
 
@@ -119,6 +115,8 @@ pub(crate) fn handle_opaque_type_uses<'tcx>(
             }
         }
 
+        debug!(?opaque_type_key, ?hidden_type, "check defining use");
+
         let opaque_type_key = opaque_type_key.fold_captured_lifetime_args(tcx, |region| {
             let scc = constraint_sccs.scc(region.as_var());
             let vid = constraint_sccs.annotation(scc).representative;
@@ -247,16 +245,19 @@ struct OpaqueHiddenTypeFolder<'a, 'tcx> {
 }
 
 impl<'tcx> OpaqueHiddenTypeFolder<'_, 'tcx> {
+    #[instrument(level = "debug", skip(self))]
     fn apply_member_constraint(&mut self, r: RegionVid) -> Option<Region<'tcx>> {
         let member = self.constraint_sccs.scc(r);
 
         if let Some((_, reg)) = self.arg_regions.iter().copied().find(|&(vid, _)| vid == r) {
+            debug!("member equal to arg");
             return Some(reg);
         }
 
         // If the member region lives in a higher universe, we currently choose
         // the most conservative option by leaving it unchanged.
         if !self.constraint_sccs.annotation(member).min_universe().is_root() {
+            debug!("member not in root universe");
             return None;
         }
 
@@ -273,6 +274,7 @@ impl<'tcx> OpaqueHiddenTypeFolder<'_, 'tcx> {
                 })
             })
             .collect::<Vec<_>>();
+        debug!(?choice_regions, "after enforcing lower-bound");
 
         // Now find all the *upper bounds* -- that is, each UB is a
         // free region that must outlive the member region `R0` (`UB:
@@ -282,6 +284,8 @@ impl<'tcx> OpaqueHiddenTypeFolder<'_, 'tcx> {
             choice_regions.retain(|&(o_r, _)| self.universal_region_relations.outlives(ub, o_r));
         }
 
+        debug!(?choice_regions, "after enforcing upper-bound");
+
         // At this point we can pick any member of `choice_regions` and would like to choose
         // it to be a small as possible. To avoid potential non-determinism we will pick the
         // smallest such choice.
@@ -319,7 +323,7 @@ impl<'tcx> OpaqueHiddenTypeFolder<'_, 'tcx> {
             debug!("no unique minimum choice");
             return None;
         };
-
+        debug!(?min_choice);
         Some(min_choice)
     }