Refactor fold_free_universal_lifetime to take a UniversalIndex

Author: leoyvens

chalk-ir/src/fold.rs

@@ -140,7 +140,7 @@ pub trait UniversalFolder {
     /// As with `fold_free_universal_ty`, but for lifetimes.
     fn fold_free_universal_lifetime(
         &mut self,
-        universe: UniverseIndex,
+        universe: UniversalIndex,
         binders: usize,
     ) -> Fallible<Lifetime>;
 }
@@ -157,7 +157,7 @@ impl<T: IdentityUniversalFolder> UniversalFolder for T {
 
     fn fold_free_universal_lifetime(
         &mut self,
-        universe: UniverseIndex,
+        universe: UniversalIndex,
         _binders: usize,
     ) -> Fallible<Lifetime> {
         Ok(universe.to_lifetime())
@@ -349,7 +349,7 @@ pub fn super_fold_lifetime(
         } else {
             Ok(Lifetime::Var(depth))
         },
-        Lifetime::ForAll(universe) => folder.fold_free_universal_lifetime(universe.ui, binders),
+        Lifetime::ForAll(universe) => folder.fold_free_universal_lifetime(universe, binders),
     }
 }
 

chalk-ir/src/lib.rs

@@ -134,10 +134,6 @@ impl UniverseIndex {
         self.counter >= ui.counter
     }
 
-    pub fn to_lifetime(self) -> Lifetime {
-        Lifetime::ForAll(UniversalIndex { ui: self, idx: 0 })
-    }
-
     pub fn next(self) -> UniverseIndex {
         UniverseIndex {
             counter: self.counter + 1,
@@ -220,6 +216,12 @@ pub struct UniversalIndex {
     pub idx: usize,
 }
 
+impl UniversalIndex {
+    pub fn to_lifetime(self) -> Lifetime {
+        Lifetime::ForAll(self)
+    }
+}
+
 #[derive(Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct ApplicationTy {
     pub name: TypeName,

chalk-solve/src/infer/canonicalize.rs

@@ -101,10 +101,10 @@ impl<'q> UniversalFolder for Canonicalizer<'q> {
 
     fn fold_free_universal_lifetime(
         &mut self,
-        universe: UniverseIndex,
+        universe: UniversalIndex,
         _binders: usize,
     ) -> Fallible<Lifetime> {
-        self.max_universe = max(self.max_universe, universe);
+        self.max_universe = max(self.max_universe, universe.ui);
         Ok(universe.to_lifetime())
     }
 }

chalk-solve/src/infer/invert.rs

@@ -98,7 +98,7 @@ impl InferenceTable {
 struct Inverter<'q> {
     table: &'q mut InferenceTable,
     inverted_ty: HashMap<UniverseIndex, InferenceVariable>,
-    inverted_lifetime: HashMap<UniverseIndex, InferenceVariable>,
+    inverted_lifetime: HashMap<UniversalIndex, InferenceVariable>,
 }
 
 impl<'q> Inverter<'q> {
@@ -127,14 +127,14 @@ impl<'q> UniversalFolder for Inverter<'q> {
 
     fn fold_free_universal_lifetime(
         &mut self,
-        universe: UniverseIndex,
+        universe: UniversalIndex,
         binders: usize,
     ) -> Fallible<Lifetime> {
         let table = &mut self.table;
         Ok(
             self.inverted_lifetime
                 .entry(universe)
-                .or_insert_with(|| table.new_variable(universe))
+                .or_insert_with(|| table.new_variable(universe.ui))
                 .to_lifetime()
                 .shifted_in(binders),
         )

chalk-solve/src/infer/ucanonicalize.rs

@@ -227,10 +227,10 @@ impl<'q> UniversalFolder for UCollector<'q> {
 
     fn fold_free_universal_lifetime(
         &mut self,
-        universe: UniverseIndex,
+        universe: UniversalIndex,
         _binders: usize,
     ) -> Fallible<Lifetime> {
-        self.universes.add(universe);
+        self.universes.add(universe.ui);
         Ok(universe.to_lifetime())
     }
 }
@@ -255,11 +255,11 @@ impl<'q> UniversalFolder for UMapToCanonical<'q> {
 
     fn fold_free_universal_lifetime(
         &mut self,
-        universe0: UniverseIndex,
+        universe0: UniversalIndex,
         _binders: usize,
     ) -> Fallible<Lifetime> {
-        let universe = self.universes.map_universe_to_canonical(universe0);
-        Ok(universe.to_lifetime())
+        let universe = self.universes.map_universe_to_canonical(universe0.ui);
+        Ok(UniversalIndex { ui: universe, idx: universe0.idx }.to_lifetime())
     }
 }
 
@@ -283,11 +283,11 @@ impl<'q> UniversalFolder for UMapFromCanonical<'q> {
 
     fn fold_free_universal_lifetime(
         &mut self,
-        universe0: UniverseIndex,
+        universe0: UniversalIndex,
         _binders: usize,
     ) -> Fallible<Lifetime> {
-        let universe = self.universes.map_universe_from_canonical(universe0);
-        Ok(universe.to_lifetime())
+        let universe = self.universes.map_universe_from_canonical(universe0.ui);
+        Ok(UniversalIndex { ui: universe, idx: universe0.idx }.to_lifetime())
     }
 }
 

chalk-solve/src/infer/unify.rs

@@ -384,10 +384,10 @@ impl<'u, 't> UniversalFolder for OccursCheck<'u, 't> {
 
     fn fold_free_universal_lifetime(
         &mut self,
-        ui: UniverseIndex,
+        ui: UniversalIndex,
         binders: usize,
     ) -> Fallible<Lifetime> {
-        if self.universe_index < ui {
+        if self.universe_index < ui.ui {
             // Scenario is like:
             //
             // exists<T> forall<'b> ?T = Foo<'b>