1 files changed, 26 insertions, 33 deletions

diff --git a/compiler/rustc_traits/src/chalk/mod.rs b/compiler/rustc_traits/src/chalk/mod.rs
index f76386fa7..a5ebc26a8 100644
--- a/compiler/rustc_traits/src/chalk/mod.rs
+++ b/compiler/rustc_traits/src/chalk/mod.rs
@@ -6,15 +6,10 @@
 pub(crate) mod db;
 pub(crate) mod lowering;
 
-use rustc_data_structures::fx::FxHashMap;
-
-use rustc_index::vec::IndexVec;
-
 use rustc_middle::infer::canonical::{CanonicalTyVarKind, CanonicalVarKind};
 use rustc_middle::traits::ChalkRustInterner;
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::subst::GenericArg;
-use rustc_middle::ty::{self, BoundVar, ParamTy, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, TyCtxt, TypeFoldable, TypeVisitable};
 
 use rustc_infer::infer::canonical::{
     Canonical, CanonicalVarValues, Certainty, QueryRegionConstraints, QueryResponse,
@@ -44,7 +39,7 @@ pub(crate) fn evaluate_goal<'tcx>(
     let mut params_substitutor =
         ParamsSubstitutor::new(tcx, placeholders_collector.next_ty_placeholder);
     let obligation = obligation.fold_with(&mut params_substitutor);
-    let params: FxHashMap<usize, ParamTy> = params_substitutor.params;
+    let params = params_substitutor.params;
 
     let max_universe = obligation.max_universe.index();
 
@@ -100,36 +95,35 @@ pub(crate) fn evaluate_goal<'tcx>(
                          binders: chalk_ir::CanonicalVarKinds<_>| {
         use rustc_middle::infer::canonical::CanonicalVarInfo;
 
-        let mut var_values: IndexVec<BoundVar, GenericArg<'tcx>> = IndexVec::new();
         let mut reverse_param_substitutor = ReverseParamsSubstitutor::new(tcx, params);
-        subst.as_slice(interner).iter().for_each(|p| {
-            var_values.push(p.lower_into(interner).fold_with(&mut reverse_param_substitutor));
-        });
-        let variables: Vec<_> = binders
-            .iter(interner)
-            .map(|var| {
-                let kind = match var.kind {
-                    chalk_ir::VariableKind::Ty(ty_kind) => CanonicalVarKind::Ty(match ty_kind {
-                        chalk_ir::TyVariableKind::General => CanonicalTyVarKind::General(
-                            ty::UniverseIndex::from_usize(var.skip_kind().counter),
-                        ),
-                        chalk_ir::TyVariableKind::Integer => CanonicalTyVarKind::Int,
-                        chalk_ir::TyVariableKind::Float => CanonicalTyVarKind::Float,
-                    }),
-                    chalk_ir::VariableKind::Lifetime => CanonicalVarKind::Region(
+        let var_values = tcx.mk_substs_from_iter(
+            subst
+                .as_slice(interner)
+                .iter()
+                .map(|p| p.lower_into(interner).fold_with(&mut reverse_param_substitutor)),
+        );
+        let variables = binders.iter(interner).map(|var| {
+            let kind = match var.kind {
+                chalk_ir::VariableKind::Ty(ty_kind) => CanonicalVarKind::Ty(match ty_kind {
+                    chalk_ir::TyVariableKind::General => CanonicalTyVarKind::General(
                         ty::UniverseIndex::from_usize(var.skip_kind().counter),
                     ),
-                    // FIXME(compiler-errors): We don't currently have a way of turning
-                    // a Chalk ty back into a rustc ty, right?
-                    chalk_ir::VariableKind::Const(_) => todo!(),
-                };
-                CanonicalVarInfo { kind }
-            })
-            .collect();
+                    chalk_ir::TyVariableKind::Integer => CanonicalTyVarKind::Int,
+                    chalk_ir::TyVariableKind::Float => CanonicalTyVarKind::Float,
+                }),
+                chalk_ir::VariableKind::Lifetime => {
+                    CanonicalVarKind::Region(ty::UniverseIndex::from_usize(var.skip_kind().counter))
+                }
+                // FIXME(compiler-errors): We don't currently have a way of turning
+                // a Chalk ty back into a rustc ty, right?
+                chalk_ir::VariableKind::Const(_) => todo!(),
+            };
+            CanonicalVarInfo { kind }
+        });
         let max_universe = binders.iter(interner).map(|v| v.skip_kind().counter).max().unwrap_or(0);
         let sol = Canonical {
             max_universe: ty::UniverseIndex::from_usize(max_universe),
-            variables: tcx.intern_canonical_var_infos(&variables),
+            variables: tcx.mk_canonical_var_infos_from_iter(variables),
             value: QueryResponse {
                 var_values: CanonicalVarValues { var_values },
                 region_constraints: QueryRegionConstraints::default(),
@@ -159,8 +153,7 @@ pub(crate) fn evaluate_goal<'tcx>(
                             max_universe: ty::UniverseIndex::from_usize(0),
                             variables: obligation.variables,
                             value: QueryResponse {
-                                var_values: CanonicalVarValues { var_values: IndexVec::new() }
-                                    .make_identity(tcx),
+                                var_values: CanonicalVarValues::dummy(),
                                 region_constraints: QueryRegionConstraints::default(),
                                 certainty: Certainty::Ambiguous,
                                 opaque_types: vec![],