3 files changed, 18 insertions, 9 deletions
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 80f1a0d3254..9013bea749a 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -671,6 +671,22 @@ pub struct CombinedSnapshot<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
+    /// calls `tcx.try_unify_abstract_consts` after
+    /// canonicalizing the consts.
+    pub fn try_unify_abstract_consts(
+        &self,
+        a: ty::Unevaluated<'tcx>,
+        b: ty::Unevaluated<'tcx>,
+    ) -> bool {
+        let canonical = self.canonicalize_query(
+            ((a.def, a.substs), (b.def, b.substs)),
+            &mut OriginalQueryValues::default(),
+        );
+        debug!("canonical consts: {:?}", &canonical.value);
+
+        self.tcx.try_unify_abstract_consts(canonical.value)
+    }
+
     pub fn is_in_snapshot(&self) -> bool {
         self.in_snapshot.get()
     }
diff --git a/compiler/rustc_trait_selection/src/traits/fulfill.rs b/compiler/rustc_trait_selection/src/traits/fulfill.rs
index a2095907c7a..4b94deff825 100644
--- a/compiler/rustc_trait_selection/src/traits/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/traits/fulfill.rs
@@ -578,11 +578,7 @@ impl<'a, 'b, 'tcx> FulfillProcessor<'a, 'b, 'tcx> {
                         if let (ty::ConstKind::Unevaluated(a), ty::ConstKind::Unevaluated(b)) =
                             (c1.val, c2.val)
                         {
-                            if self
-                                .selcx
-                                .tcx()
-                                .try_unify_abstract_consts(((a.def, a.substs), (b.def, b.substs)))
-                            {
+                            if infcx.try_unify_abstract_consts(a, b) {
                                 return ProcessResult::Changed(vec![]);
                             }
                         }
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index f95e7b8b6c3..c150b222266 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -624,10 +624,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         if let (ty::ConstKind::Unevaluated(a), ty::ConstKind::Unevaluated(b)) =
                             (c1.val, c2.val)
                         {
-                            if self
-                                .tcx()
-                                .try_unify_abstract_consts(((a.def, a.substs), (b.def, b.substs)))
-                            {
+                            if self.infcx.try_unify_abstract_consts(a, b) {
                                 return Ok(EvaluatedToOk);
                             }
                         }