From 696c88d69ce01cc41acd9744d120e12be260a4b6 Mon Sep 17 00:00:00 2001
From: Ellen <supbscripter@gmail.com>
Date: Thu, 19 Aug 2021 19:46:35 +0100
Subject: [PATCH] canonicalize const equate predicates

---
 .../rustc_trait_selection/src/traits/fulfill.rs     | 13 ++++++++-----
 .../rustc_trait_selection/src/traits/select/mod.rs  | 12 ++++++++----
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_trait_selection/src/traits/fulfill.rs b/compiler/rustc_trait_selection/src/traits/fulfill.rs
index 7048f0dbedc..1d44e171807 100644
--- a/compiler/rustc_trait_selection/src/traits/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/traits/fulfill.rs
@@ -4,6 +4,7 @@ use rustc_data_structures::obligation_forest::{Error, ForestObligation, Outcome}
 use rustc_data_structures::obligation_forest::{ObligationForest, ObligationProcessor};
 use rustc_errors::ErrorReported;
 use rustc_hir as hir;
+use rustc_infer::infer::canonical::OriginalQueryValues;
 use rustc_infer::traits::{SelectionError, TraitEngine, TraitEngineExt as _, TraitObligation};
 use rustc_middle::mir::abstract_const::NotConstEvaluatable;
 use rustc_middle::mir::interpret::ErrorHandled;
@@ -552,11 +553,13 @@ 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)))
-                            {
+                            let canonical = infcx.canonicalize_query(
+                                ((a.def, a.substs), (b.def, b.substs)),
+                                &mut OriginalQueryValues::default(),
+                            );
+                            debug!("canonical consts: {:?}", &canonical.value);
+
+                            if self.selcx.tcx().try_unify_abstract_consts(canonical.value) {
                                 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 dcf5ac63b78..60484b4d065 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -33,6 +33,7 @@ use rustc_errors::ErrorReported;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::Constness;
+use rustc_infer::infer::canonical::OriginalQueryValues;
 use rustc_infer::infer::LateBoundRegionConversionTime;
 use rustc_middle::dep_graph::{DepKind, DepNodeIndex};
 use rustc_middle::mir::abstract_const::NotConstEvaluatable;
@@ -608,10 +609,13 @@ 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)))
-                            {
+                            let canonical = self.infcx.canonicalize_query(
+                                ((a.def, a.substs), (b.def, b.substs)),
+                                &mut OriginalQueryValues::default(),
+                            );
+                            debug!("canonical consts: {:?}", &canonical.value);
+
+                            if self.tcx().try_unify_abstract_consts(canonical.value) {
                                 return Ok(EvaluatedToOk);
                             }
                         }