From e511cc7d49bd04cbe09450454bc573ac00c21a9b Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Fri, 24 Nov 2023 22:53:13 +0000
Subject: [PATCH] Unify TraitRefs and PolyTraitRefs

---
 compiler/rustc_infer/src/infer/at.rs             |  6 +++++-
 .../rustc_infer/src/infer/error_reporting/mod.rs | 16 +---------------
 .../nice_region_error/placeholder_error.rs       |  5 -----
 compiler/rustc_infer/src/infer/mod.rs            |  1 -
 4 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/compiler/rustc_infer/src/infer/at.rs b/compiler/rustc_infer/src/infer/at.rs
index c32c3aa6d2968..09313cd9738c2 100644
--- a/compiler/rustc_infer/src/infer/at.rs
+++ b/compiler/rustc_infer/src/infer/at.rs
@@ -448,7 +448,11 @@ impl<'tcx> ToTrace<'tcx> for ty::TraitRef<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
+            values: PolyTraitRefs(ExpectedFound::new(
+                a_is_expected,
+                ty::Binder::dummy(a),
+                ty::Binder::dummy(b),
+            )),
         }
     }
 }
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index a2aa99e78e1e9..d66990c348288 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -1667,9 +1667,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                             .report(diag);
                         (false, Mismatch::Fixed("signature"))
                     }
-                    ValuePairs::TraitRefs(_) | ValuePairs::PolyTraitRefs(_) => {
-                        (false, Mismatch::Fixed("trait"))
-                    }
+                    ValuePairs::PolyTraitRefs(_) => (false, Mismatch::Fixed("trait")),
                     ValuePairs::Aliases(infer::ExpectedFound { expected, .. }) => {
                         (false, Mismatch::Fixed(self.tcx.def_descr(expected.def_id)))
                     }
@@ -2219,18 +2217,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             infer::Aliases(exp_found) => self.expected_found_str(exp_found),
             infer::ExistentialTraitRef(exp_found) => self.expected_found_str(exp_found),
             infer::ExistentialProjection(exp_found) => self.expected_found_str(exp_found),
-            infer::TraitRefs(exp_found) => {
-                let pretty_exp_found = ty::error::ExpectedFound {
-                    expected: exp_found.expected.print_only_trait_path(),
-                    found: exp_found.found.print_only_trait_path(),
-                };
-                match self.expected_found_str(pretty_exp_found) {
-                    Some((expected, found, _, _)) if expected == found => {
-                        self.expected_found_str(exp_found)
-                    }
-                    ret => ret,
-                }
-            }
             infer::PolyTraitRefs(exp_found) => {
                 let pretty_exp_found = ty::error::ExpectedFound {
                     expected: exp_found.expected.print_only_trait_path(),
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
index c38e5b8cd09e5..d98ca995d71d4 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
@@ -197,11 +197,6 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         value_pairs: &ValuePairs<'tcx>,
     ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
         let (expected_args, found_args, trait_def_id) = match value_pairs {
-            ValuePairs::TraitRefs(ExpectedFound { expected, found })
-                if expected.def_id == found.def_id =>
-            {
-                (expected.args, found.args, expected.def_id)
-            }
             ValuePairs::PolyTraitRefs(ExpectedFound { expected, found })
                 if expected.def_id() == found.def_id() =>
             {
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index d6c7a24476f9e..739eb69929a6c 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -384,7 +384,6 @@ pub enum ValuePairs<'tcx> {
     Regions(ExpectedFound<ty::Region<'tcx>>),
     Terms(ExpectedFound<ty::Term<'tcx>>),
     Aliases(ExpectedFound<ty::AliasTy<'tcx>>),
-    TraitRefs(ExpectedFound<ty::TraitRef<'tcx>>),
     PolyTraitRefs(ExpectedFound<ty::PolyTraitRef<'tcx>>),
     PolySigs(ExpectedFound<ty::PolyFnSig<'tcx>>),
     ExistentialTraitRef(ExpectedFound<ty::PolyExistentialTraitRef<'tcx>>),