Remove `ReCanonical` in favor of `ReLateBound`

9 files changed, 59 insertions, 50 deletions

diff --git a/src/librustc/infer/canonical/canonicalizer.rs b/src/librustc/infer/canonical/canonicalizer.rs
index a54d977a517..9c70606349b 100644
--- a/src/librustc/infer/canonical/canonicalizer.rs
+++ b/src/librustc/infer/canonical/canonicalizer.rs
@@ -331,8 +331,8 @@ impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for Canonicalizer<'cx, 'gcx, 'tcx>
             | ty::ReErased => self.canonicalize_region_mode
                 .canonicalize_free_region(self, r),
 
-            ty::ReClosureBound(..) | ty::ReCanonical(_) => {
-                bug!("canonical region encountered during canonicalization")
+            ty::ReClosureBound(..) => {
+                bug!("closure bound region encountered during canonicalization")
             }
         }
     }
@@ -407,12 +407,6 @@ impl<'cx, 'gcx, 'tcx> Canonicalizer<'cx, 'gcx, 'tcx> {
     where
         V: TypeFoldable<'tcx> + Lift<'gcx>,
     {
-        debug_assert!(
-            !value.has_type_flags(TypeFlags::HAS_CANONICAL_VARS),
-            "canonicalizing a canonical value: {:?}",
-            value,
-        );
-
         let needs_canonical_flags = if canonicalize_region_mode.any() {
             TypeFlags::HAS_FREE_REGIONS | TypeFlags::KEEP_IN_LOCAL_TCX
         } else {
@@ -569,7 +563,11 @@ impl<'cx, 'gcx, 'tcx> Canonicalizer<'cx, 'gcx, 'tcx> {
         r: ty::Region<'tcx>,
     ) -> ty::Region<'tcx> {
         let var = self.canonical_var(info, r.into());
-        self.tcx().mk_region(ty::ReCanonical(var))
+        let region = ty::ReLateBound(
+            self.binder_index,
+            ty::BoundRegion::BrAnon(var.index() as u32)
+        );
+        self.tcx().mk_region(region)
     }
 
     /// Given a type variable `ty_var` of the given kind, first check
diff --git a/src/librustc/infer/canonical/mod.rs b/src/librustc/infer/canonical/mod.rs
index b6f79414725..f7eb7118f41 100644
--- a/src/librustc/infer/canonical/mod.rs
+++ b/src/librustc/infer/canonical/mod.rs
@@ -20,7 +20,7 @@
 //! - a map M (of type `CanonicalVarValues`) from those canonical
 //!   variables back to the original.
 //!
-//! We can then do queries using T2. These will give back constriants
+//! We can then do queries using T2. These will give back constraints
 //! on the canonical variables which can be translated, using the map
 //! M, into constraints in our source context. This process of
 //! translating the results back is done by the
diff --git a/src/librustc/infer/canonical/query_response.rs b/src/librustc/infer/canonical/query_response.rs
index 06e97a71ce5..4858d1d0919 100644
--- a/src/librustc/infer/canonical/query_response.rs
+++ b/src/librustc/infer/canonical/query_response.rs
@@ -308,11 +308,12 @@ impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
         // ...also include the other query region constraints from the query.
         output_query_region_constraints.extend(
             query_response.value.region_constraints.iter().filter_map(|r_c| {
-                let &ty::OutlivesPredicate(k1, r2) = r_c.skip_binder(); // reconstructed below
-                let k1 = substitute_value(self.tcx, &result_subst, &k1);
-                let r2 = substitute_value(self.tcx, &result_subst, &r2);
-                if k1 != r2.into() {
-                    Some(ty::Binder::bind(ty::OutlivesPredicate(k1, r2)))
+                let ty::OutlivesPredicate(k1, r2) = r_c.skip_binder(); // reconstructed below
+                let k1 = substitute_value(self.tcx, &result_subst, &ty::Binder::bind(*k1));
+                let r2 = substitute_value(self.tcx, &result_subst, &ty::Binder::bind(*r2));
+                if k1 != r2.map_bound(|bound| bound.into()) {
+                    let predicate = ty::OutlivesPredicate(*k1.skip_binder(), *r2.skip_binder());
+                    Some(ty::Binder::bind(predicate))
                 } else {
                     None
                 }
@@ -433,16 +434,21 @@ impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
                 UnpackedKind::Type(result_value) => {
                     // e.g., here `result_value` might be `?0` in the example above...
                     if let ty::Bound(b) = result_value.sty {
+                        // ...in which case we would set `canonical_vars[0]` to `Some(?U)`.
+
+                        // We only allow a `ty::INNERMOST` index in substitutions.
                         assert_eq!(b.index, ty::INNERMOST);
-                        // in which case we would set `canonical_vars[0]` to `Some(?U)`.
                         opt_values[b.var] = Some(*original_value);
                     }
                 }
                 UnpackedKind::Lifetime(result_value) => {
                     // e.g., here `result_value` might be `'?1` in the example above...
-                    if let &ty::RegionKind::ReCanonical(index) = result_value {
-                        // in which case we would set `canonical_vars[0]` to `Some('static)`.
-                        opt_values[index] = Some(*original_value);
+                    if let &ty::RegionKind::ReLateBound(index, br) = result_value {
+                        // ... in which case we would set `canonical_vars[0]` to `Some('static)`.
+
+                        // We only allow a `ty::INNERMOST` index in substitutions.
+                        assert_eq!(index, ty::INNERMOST);
+                        opt_values[br.as_bound_var()] = Some(*original_value);
                     }
                 }
             }
@@ -525,21 +531,23 @@ impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
                 .iter()
                 .map(move |constraint| {
                     let ty::OutlivesPredicate(k1, r2) = constraint.skip_binder(); // restored below
-                    let k1 = substitute_value(self.tcx, result_subst, k1);
-                    let r2 = substitute_value(self.tcx, result_subst, r2);
+                    let k1 = substitute_value(self.tcx, result_subst, &ty::Binder::bind(*k1));
+                    let r2 = substitute_value(self.tcx, result_subst, &ty::Binder::bind(*r2));
 
                     Obligation::new(
                         cause.clone(),
                         param_env,
-                        match k1.unpack() {
+                        match k1.skip_binder().unpack() {
                             UnpackedKind::Lifetime(r1) => ty::Predicate::RegionOutlives(
-                                ty::Binder::dummy(
-                                    ty::OutlivesPredicate(r1, r2)
-                            )),
+                                ty::Binder::bind(
+                                    ty::OutlivesPredicate(r1, r2.skip_binder())
+                                )
+                            ),
                             UnpackedKind::Type(t1) => ty::Predicate::TypeOutlives(
-                                ty::Binder::dummy(ty::OutlivesPredicate(
-                                    t1, r2
-                            )))
+                                ty::Binder::bind(
+                                    ty::OutlivesPredicate(t1, r2.skip_binder())
+                                )
+                            ),
                         }
                     )
                 })
@@ -621,11 +629,11 @@ pub fn make_query_outlives<'tcx>(
             }
             Constraint::RegSubReg(r1, r2) => ty::OutlivesPredicate(r2.into(), r1),
         })
-        .map(ty::Binder::dummy) // no bound regions in the code above
+        .map(ty::Binder::dummy) // no bound vars in the code above
         .chain(
             outlives_obligations
                 .map(|(ty, r)| ty::OutlivesPredicate(ty.into(), r))
-                .map(ty::Binder::dummy), // no bound regions in the code above
+                .map(ty::Binder::dummy) // no bound vars in the code above
         )
         .collect();
 
diff --git a/src/librustc/infer/canonical/substitute.rs b/src/librustc/infer/canonical/substitute.rs
index 5b2e758d816..7839c892266 100644
--- a/src/librustc/infer/canonical/substitute.rs
+++ b/src/librustc/infer/canonical/substitute.rs
@@ -19,7 +19,7 @@
 use infer::canonical::{Canonical, CanonicalVarValues};
 use ty::fold::{TypeFoldable, TypeFolder};
 use ty::subst::UnpackedKind;
-use ty::{self, Ty, TyCtxt, TypeFlags};
+use ty::{self, Ty, TyCtxt};
 
 impl<'tcx, V> Canonical<'tcx, V> {
     /// Instantiate the wrapped value, replacing each canonical value
@@ -64,9 +64,9 @@ where
     T: TypeFoldable<'tcx>,
 {
     if var_values.var_values.is_empty() {
-        debug_assert!(!value.has_type_flags(TypeFlags::HAS_CANONICAL_VARS));
         value.clone()
-    } else if !value.has_type_flags(TypeFlags::HAS_CANONICAL_VARS) {
+    } else if !value.has_escaping_bound_vars() {
+        // There are no bound vars to substitute.
         value.clone()
     } else {
         value.fold_with(&mut CanonicalVarValuesSubst {
@@ -104,8 +104,8 @@ impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for CanonicalVarValuesSubst<'cx, 'g
                     match self.var_values.var_values[b.var].unpack() {
                         UnpackedKind::Type(ty) => ty::fold::shift_vars(
                             self.tcx,
-                            self.binder_index.index() as u32,
-                            &ty
+                            &ty,
+                            self.binder_index.index() as u32
                         ),
                         r => bug!("{:?} is a type but value is {:?}", b, r),
                     }
@@ -114,7 +114,8 @@ impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for CanonicalVarValuesSubst<'cx, 'g
                 }
             }
             _ => {
-                if !t.has_type_flags(TypeFlags::HAS_CANONICAL_VARS) {
+                if !t.has_vars_bound_at_or_above(self.binder_index) {
+                    // Nothing more to substitute.
                     t
                 } else {
                     t.super_fold_with(self)
@@ -125,10 +126,20 @@ impl<'cx, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for CanonicalVarValuesSubst<'cx, 'g
 
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match r {
-            ty::RegionKind::ReCanonical(c) => match self.var_values.var_values[*c].unpack() {
-                UnpackedKind::Lifetime(l) => l,
-                r => bug!("{:?} is a region but value is {:?}", c, r),
-            },
+            ty::RegionKind::ReLateBound(index, br) => {
+                if *index == self.binder_index {
+                    match self.var_values.var_values[br.as_bound_var()].unpack() {
+                        UnpackedKind::Lifetime(l) => ty::fold::shift_region(
+                            self.tcx,
+                            l,
+                            self.binder_index.index() as u32,
+                        ),
+                        r => bug!("{:?} is a region but value is {:?}", br, r),
+                    }
+                } else {
+                    r
+                }
+            }
             _ => r.super_fold_with(self),
         }
     }
diff --git a/src/librustc/infer/combine.rs b/src/librustc/infer/combine.rs
index 0ee03bc4c6e..f13210926a7 100644
--- a/src/librustc/infer/combine.rs
+++ b/src/librustc/infer/combine.rs
@@ -485,7 +485,6 @@ impl<'cx, 'gcx, 'tcx> TypeRelation<'cx, 'gcx, 'tcx> for Generalizer<'cx, 'gcx, '
                 }
             }
 
-            ty::ReCanonical(..) |
             ty::ReClosureBound(..) => {
                 span_bug!(
                     self.span,
diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index d19c495af3b..1963d366e7a 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -152,7 +152,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             }
 
             // We shouldn't encounter an error message with ReClosureBound.
-            ty::ReCanonical(..) | ty::ReClosureBound(..) => {
+            ty::ReClosureBound(..) => {
                 bug!("encountered unexpected ReClosureBound: {:?}", region,);
             }
         };
diff --git a/src/librustc/infer/freshen.rs b/src/librustc/infer/freshen.rs
index c12e64b4c2c..b53444992fa 100644
--- a/src/librustc/infer/freshen.rs
+++ b/src/librustc/infer/freshen.rs
@@ -114,7 +114,6 @@ impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for TypeFreshener<'a, 'gcx, 'tcx> {
                 self.tcx().types.re_erased
             }
 
-            ty::ReCanonical(..) |
             ty::ReClosureBound(..) => {
                 bug!(
                     "encountered unexpected region: {:?}",
diff --git a/src/librustc/infer/lexical_region_resolve/mod.rs b/src/librustc/infer/lexical_region_resolve/mod.rs
index 8f28e9a320d..75f503d3bcf 100644
--- a/src/librustc/infer/lexical_region_resolve/mod.rs
+++ b/src/librustc/infer/lexical_region_resolve/mod.rs
@@ -260,9 +260,7 @@ impl<'cx, 'gcx, 'tcx> LexicalResolver<'cx, 'gcx, 'tcx> {
     fn lub_concrete_regions(&self, a: Region<'tcx>, b: Region<'tcx>) -> Region<'tcx> {
         let tcx = self.tcx();
         match (a, b) {
-            (&ty::ReCanonical(..), _)
-            | (_, &ty::ReCanonical(..))
-            | (&ty::ReClosureBound(..), _)
+            (&ty::ReClosureBound(..), _)
             | (_, &ty::ReClosureBound(..))
             | (&ReLateBound(..), _)
             | (_, &ReLateBound(..))
diff --git a/src/librustc/infer/region_constraints/mod.rs b/src/librustc/infer/region_constraints/mod.rs
index c82603bf560..46b12d01829 100644
--- a/src/librustc/infer/region_constraints/mod.rs
+++ b/src/librustc/infer/region_constraints/mod.rs
@@ -833,10 +833,6 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
             ty::RePlaceholder(placeholder) => placeholder.universe,
             ty::ReClosureBound(vid) | ty::ReVar(vid) => self.var_universe(vid),
             ty::ReLateBound(..) => bug!("universe(): encountered bound region {:?}", region),
-            ty::ReCanonical(..) => bug!(
-                "region_universe(): encountered canonical region {:?}",
-                region
-            ),
         }
     }