1 files changed, 44 insertions, 36 deletions

diff --git a/crates/hir_ty/src/infer/unify.rs b/crates/hir_ty/src/infer/unify.rs
index 6e7b0f5a6..b7bc48569 100644
--- a/crates/hir_ty/src/infer/unify.rs
+++ b/crates/hir_ty/src/infer/unify.rs
@@ -49,7 +49,7 @@ impl<'a, 'b> Canonicalizer<'a, 'b> {
 
     fn do_canonicalize<T: TypeWalk>(&mut self, t: T, binders: DebruijnIndex) -> T {
         t.fold_binders(
-            &mut |ty, binders| match ty.interned(&Interner) {
+            &mut |ty, binders| match ty.kind(&Interner) {
                 &TyKind::InferenceVar(var, kind) => {
                     let inner = var.to_inner();
                     if self.var_stack.contains(&inner) {
@@ -129,29 +129,28 @@ impl<T> Canonicalized<T> {
         solution: Canonical<Substitution>,
     ) {
         // the solution may contain new variables, which we need to convert to new inference vars
-        let new_vars = Substitution(
-            solution
-                .binders
-                .iter(&Interner)
-                .map(|k| match k.kind {
-                    VariableKind::Ty(TyVariableKind::General) => ctx.table.new_type_var(),
-                    VariableKind::Ty(TyVariableKind::Integer) => ctx.table.new_integer_var(),
-                    VariableKind::Ty(TyVariableKind::Float) => ctx.table.new_float_var(),
-                    // HACK: Chalk can sometimes return new lifetime variables. We
-                    // want to just skip them, but to not mess up the indices of
-                    // other variables, we'll just create a new type variable in
-                    // their place instead. This should not matter (we never see the
-                    // actual *uses* of the lifetime variable).
-                    VariableKind::Lifetime => ctx.table.new_type_var(),
-                    _ => panic!("const variable in solution"),
-                })
-                .collect(),
+        let new_vars = Substitution::from_iter(
+            &Interner,
+            solution.binders.iter(&Interner).map(|k| match k.kind {
+                VariableKind::Ty(TyVariableKind::General) => ctx.table.new_type_var(),
+                VariableKind::Ty(TyVariableKind::Integer) => ctx.table.new_integer_var(),
+                VariableKind::Ty(TyVariableKind::Float) => ctx.table.new_float_var(),
+                // HACK: Chalk can sometimes return new lifetime variables. We
+                // want to just skip them, but to not mess up the indices of
+                // other variables, we'll just create a new type variable in
+                // their place instead. This should not matter (we never see the
+                // actual *uses* of the lifetime variable).
+                VariableKind::Lifetime => ctx.table.new_type_var(),
+                _ => panic!("const variable in solution"),
+            }),
         );
-        for (i, ty) in solution.value.into_iter().enumerate() {
+        for (i, ty) in solution.value.iter(&Interner).enumerate() {
             let (v, k) = self.free_vars[i];
             // eagerly replace projections in the type; we may be getting types
             // e.g. from where clauses where this hasn't happened yet
-            let ty = ctx.normalize_associated_types_in(ty.clone().subst_bound_vars(&new_vars));
+            let ty = ctx.normalize_associated_types_in(
+                ty.assert_ty_ref(&Interner).clone().subst_bound_vars(&new_vars),
+            );
             ctx.table.unify(&TyKind::InferenceVar(v, k).intern(&Interner), &ty);
         }
     }
@@ -163,13 +162,13 @@ pub fn could_unify(t1: &Ty, t2: &Ty) -> bool {
 
 pub(crate) fn unify(tys: &Canonical<(Ty, Ty)>) -> Option<Substitution> {
     let mut table = InferenceTable::new();
-    let vars = Substitution(
+    let vars = Substitution::from_iter(
+        &Interner,
         tys.binders
             .iter(&Interner)
             // we always use type vars here because we want everything to
             // fallback to Unknown in the end (kind of hacky, as below)
-            .map(|_| table.new_type_var())
-            .collect(),
+            .map(|_| table.new_type_var()),
     );
     let ty1_with_vars = tys.value.0.clone().subst_bound_vars(&vars);
     let ty2_with_vars = tys.value.1.clone().subst_bound_vars(&vars);
@@ -178,7 +177,8 @@ pub(crate) fn unify(tys: &Canonical<(Ty, Ty)>) -> Option<Substitution> {
     }
     // default any type vars that weren't unified back to their original bound vars
     // (kind of hacky)
-    for (i, var) in vars.iter().enumerate() {
+    for (i, var) in vars.iter(&Interner).enumerate() {
+        let var = var.assert_ty_ref(&Interner);
         if &*table.resolve_ty_shallow(var) == var {
             table.unify(
                 var,
@@ -186,11 +186,11 @@ pub(crate) fn unify(tys: &Canonical<(Ty, Ty)>) -> Option<Substitution> {
             );
         }
     }
-    Some(
-        Substitution::builder(tys.binders.len(&Interner))
-            .fill(vars.iter().map(|v| table.resolve_ty_completely(v.clone())))
-            .build(),
-    )
+    Some(Substitution::from_iter(
+        &Interner,
+        vars.iter(&Interner)
+            .map(|v| table.resolve_ty_completely(v.assert_ty_ref(&Interner).clone())),
+    ))
 }
 
 #[derive(Clone, Debug)]
@@ -231,6 +231,7 @@ pub(crate) struct TypeVariableData {
 pub(crate) struct InferenceTable {
     pub(super) var_unification_table: InPlaceUnificationTable<TypeVarId>,
     pub(super) type_variable_table: TypeVariableTable,
+    pub(super) revision: u32,
 }
 
 impl InferenceTable {
@@ -238,6 +239,7 @@ impl InferenceTable {
         InferenceTable {
             var_unification_table: InPlaceUnificationTable::new(),
             type_variable_table: TypeVariableTable { inner: Vec::new() },
+            revision: 0,
         }
     }
 
@@ -282,7 +284,9 @@ impl InferenceTable {
         substs2: &Substitution,
         depth: usize,
     ) -> bool {
-        substs1.0.iter().zip(substs2.0.iter()).all(|(t1, t2)| self.unify_inner(t1, t2, depth))
+        substs1.iter(&Interner).zip(substs2.iter(&Interner)).all(|(t1, t2)| {
+            self.unify_inner(t1.assert_ty_ref(&Interner), t2.assert_ty_ref(&Interner), depth)
+        })
     }
 
     fn unify_inner(&mut self, ty1: &Ty, ty2: &Ty, depth: usize) -> bool {
@@ -297,7 +301,7 @@ impl InferenceTable {
         let ty1 = self.resolve_ty_shallow(ty1);
         let ty2 = self.resolve_ty_shallow(ty2);
         if ty1.equals_ctor(&ty2) {
-            match (ty1.interned(&Interner), ty2.interned(&Interner)) {
+            match (ty1.kind(&Interner), ty2.kind(&Interner)) {
                 (TyKind::Adt(_, substs1), TyKind::Adt(_, substs2))
                 | (TyKind::FnDef(_, substs1), TyKind::FnDef(_, substs2))
                 | (
@@ -322,7 +326,7 @@ impl InferenceTable {
     }
 
     pub(super) fn unify_inner_trivial(&mut self, ty1: &Ty, ty2: &Ty, depth: usize) -> bool {
-        match (ty1.interned(&Interner), ty2.interned(&Interner)) {
+        match (ty1.kind(&Interner), ty2.kind(&Interner)) {
             (TyKind::Unknown, _) | (_, TyKind::Unknown) => true,
 
             (TyKind::Placeholder(p1), TyKind::Placeholder(p2)) if *p1 == *p2 => true,
@@ -360,7 +364,10 @@ impl InferenceTable {
                 == self.type_variable_table.is_diverging(*tv2) =>
             {
                 // both type vars are unknown since we tried to resolve them
-                self.var_unification_table.union(tv1.to_inner(), tv2.to_inner());
+                if !self.var_unification_table.unioned(tv1.to_inner(), tv2.to_inner()) {
+                    self.var_unification_table.union(tv1.to_inner(), tv2.to_inner());
+                    self.revision += 1;
+                }
                 true
             }
 
@@ -398,6 +405,7 @@ impl InferenceTable {
                     tv.to_inner(),
                     TypeVarValue::Known(other.clone().intern(&Interner)),
                 );
+                self.revision += 1;
                 true
             }
 
@@ -447,7 +455,7 @@ impl InferenceTable {
             if i > 0 {
                 cov_mark::hit!(type_var_resolves_to_int_var);
             }
-            match ty.interned(&Interner) {
+            match ty.kind(&Interner) {
                 TyKind::InferenceVar(tv, _) => {
                     let inner = tv.to_inner();
                     match self.var_unification_table.inlined_probe_value(inner).known() {
@@ -470,7 +478,7 @@ impl InferenceTable {
     /// be resolved as far as possible, i.e. contain no type variables with
     /// known type.
     fn resolve_ty_as_possible_inner(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
-        ty.fold(&mut |ty| match ty.interned(&Interner) {
+        ty.fold(&mut |ty| match ty.kind(&Interner) {
             &TyKind::InferenceVar(tv, kind) => {
                 let inner = tv.to_inner();
                 if tv_stack.contains(&inner) {
@@ -497,7 +505,7 @@ impl InferenceTable {
     /// Resolves the type completely; type variables without known type are
     /// replaced by TyKind::Unknown.
     fn resolve_ty_completely_inner(&mut self, tv_stack: &mut Vec<TypeVarId>, ty: Ty) -> Ty {
-        ty.fold(&mut |ty| match ty.interned(&Interner) {
+        ty.fold(&mut |ty| match ty.kind(&Interner) {
             &TyKind::InferenceVar(tv, kind) => {
                 let inner = tv.to_inner();
                 if tv_stack.contains(&inner) {