Auto merge of #90648 - matthewjasper:assoc-item-cleanup, r=cjgillot

Assoc item cleanup

This removes some fields from ObligationCauseCode

Split out of #90639

9 files changed, 29 insertions, 62 deletions

diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 8849d623b2d..298346c373e 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -2190,14 +2190,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
 
         if let Some(SubregionOrigin::CompareImplMethodObligation {
             span,
-            item_name,
             impl_item_def_id,
             trait_item_def_id,
         }) = origin
         {
             return self.report_extra_impl_obligation(
                 span,
-                item_name,
                 impl_item_def_id,
                 trait_item_def_id,
                 &format!("`{}: {}`", bound_kind, sub),
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
index b9e7ee12bc8..cfa79213c80 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
@@ -54,12 +54,16 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         {
             if let SubregionOrigin::CompareImplTypeObligation {
                 span,
-                item_name,
                 impl_item_def_id,
                 trait_item_def_id,
             } = origin
             {
-                self.emit_associated_type_err(span, item_name, impl_item_def_id, trait_item_def_id);
+                self.emit_associated_type_err(
+                    span,
+                    self.infcx.tcx.item_name(impl_item_def_id),
+                    impl_item_def_id,
+                    trait_item_def_id,
+                );
                 return Some(ErrorReported);
             }
         }
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note.rs b/compiler/rustc_infer/src/infer/error_reporting/note.rs
index 167a8893a11..6600c18351f 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/note.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/note.rs
@@ -330,30 +330,21 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 );
                 err
             }
-            infer::CompareImplMethodObligation {
-                span,
-                item_name,
-                impl_item_def_id,
-                trait_item_def_id,
-            } => self.report_extra_impl_obligation(
-                span,
-                item_name,
-                impl_item_def_id,
-                trait_item_def_id,
-                &format!("`{}: {}`", sup, sub),
-            ),
-            infer::CompareImplTypeObligation {
-                span,
-                item_name,
-                impl_item_def_id,
-                trait_item_def_id,
-            } => self.report_extra_impl_obligation(
-                span,
-                item_name,
-                impl_item_def_id,
-                trait_item_def_id,
-                &format!("`{}: {}`", sup, sub),
-            ),
+            infer::CompareImplMethodObligation { span, impl_item_def_id, trait_item_def_id } => {
+                self.report_extra_impl_obligation(
+                    span,
+                    impl_item_def_id,
+                    trait_item_def_id,
+                    &format!("`{}: {}`", sup, sub),
+                )
+            }
+            infer::CompareImplTypeObligation { span, impl_item_def_id, trait_item_def_id } => self
+                .report_extra_impl_obligation(
+                    span,
+                    impl_item_def_id,
+                    trait_item_def_id,
+                    &format!("`{}: {}`", sup, sub),
+                ),
         }
     }
 
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 9dae978dcde..32d3db39d64 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -419,21 +419,11 @@ pub enum SubregionOrigin<'tcx> {
 
     /// Comparing the signature and requirements of an impl method against
     /// the containing trait.
-    CompareImplMethodObligation {
-        span: Span,
-        item_name: Symbol,
-        impl_item_def_id: DefId,
-        trait_item_def_id: DefId,
-    },
+    CompareImplMethodObligation { span: Span, impl_item_def_id: DefId, trait_item_def_id: DefId },
 
     /// Comparing the signature and requirements of an impl associated type
     /// against the containing trait
-    CompareImplTypeObligation {
-        span: Span,
-        item_name: Symbol,
-        impl_item_def_id: DefId,
-        trait_item_def_id: DefId,
-    },
+    CompareImplTypeObligation { span: Span, impl_item_def_id: DefId, trait_item_def_id: DefId },
 }
 
 // `SubregionOrigin` is used a lot. Make sure it doesn't unintentionally get bigger.
@@ -1830,23 +1820,19 @@ impl<'tcx> SubregionOrigin<'tcx> {
             }
 
             traits::ObligationCauseCode::CompareImplMethodObligation {
-                item_name,
                 impl_item_def_id,
                 trait_item_def_id,
             } => SubregionOrigin::CompareImplMethodObligation {
                 span: cause.span,
-                item_name,
                 impl_item_def_id,
                 trait_item_def_id,
             },
 
             traits::ObligationCauseCode::CompareImplTypeObligation {
-                item_name,
                 impl_item_def_id,
                 trait_item_def_id,
             } => SubregionOrigin::CompareImplTypeObligation {
                 span: cause.span,
-                item_name,
                 impl_item_def_id,
                 trait_item_def_id,
             },
diff --git a/compiler/rustc_infer/src/traits/error_reporting/mod.rs b/compiler/rustc_infer/src/traits/error_reporting/mod.rs
index 9dbfa3a850b..c1f302e665d 100644
--- a/compiler/rustc_infer/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/traits/error_reporting/mod.rs
@@ -6,7 +6,6 @@ use rustc_errors::{struct_span_err, DiagnosticBuilder};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::TyCtxt;
-use rustc_span::symbol::Symbol;
 use rustc_span::{MultiSpan, Span};
 use std::fmt;
 use std::iter;
@@ -15,8 +14,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     pub fn report_extra_impl_obligation(
         &self,
         error_span: Span,
-        item_name: Symbol,
-        _impl_item_def_id: DefId,
+        impl_item_def_id: DefId,
         trait_item_def_id: DefId,
         requirement: &dyn fmt::Display,
     ) -> DiagnosticBuilder<'tcx> {
@@ -27,6 +25,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
 
         if let Some(trait_item_span) = self.tcx.hir().span_if_local(trait_item_def_id) {
             let span = self.tcx.sess.source_map().guess_head_span(trait_item_span);
+            let item_name = self.tcx.item_name(impl_item_def_id);
             err.span_label(span, format!("definition of `{}` from trait", item_name));
         }
 
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index 6570d8e1567..245df636107 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -267,14 +267,12 @@ pub enum ObligationCauseCode<'tcx> {
 
     /// Error derived when matching traits/impls; see ObligationCause for more details
     CompareImplMethodObligation {
-        item_name: Symbol,
         impl_item_def_id: DefId,
         trait_item_def_id: DefId,
     },
 
     /// Error derived when matching traits/impls; see ObligationCause for more details
     CompareImplTypeObligation {
-        item_name: Symbol,
         impl_item_def_id: DefId,
         trait_item_def_id: DefId,
     },
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index 0b88eb7572a..79194718d1e 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -266,19 +266,16 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     }
                 }
                 if let ObligationCauseCode::CompareImplMethodObligation {
-                    item_name,
                     impl_item_def_id,
                     trait_item_def_id,
                 }
                 | ObligationCauseCode::CompareImplTypeObligation {
-                    item_name,
                     impl_item_def_id,
                     trait_item_def_id,
                 } = obligation.cause.code
                 {
                     self.report_extra_impl_obligation(
                         span,
-                        item_name,
                         impl_item_def_id,
                         trait_item_def_id,
                         &format!("`{}`", obligation.predicate),
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index b21936a00b0..7d9568e0ca3 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -2354,11 +2354,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     )
                 });
             }
-            ObligationCauseCode::CompareImplMethodObligation {
-                item_name,
-                trait_item_def_id,
-                ..
-            } => {
+            ObligationCauseCode::CompareImplMethodObligation { trait_item_def_id, .. } => {
+                let item_name = self.tcx.item_name(trait_item_def_id);
                 let msg = format!(
                     "the requirement `{}` appears on the impl method `{}` but not on the \
                      corresponding trait method",
@@ -2383,9 +2380,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 }
                 err.span_note(assoc_span, &msg);
             }
-            ObligationCauseCode::CompareImplTypeObligation {
-                item_name, trait_item_def_id, ..
-            } => {
+            ObligationCauseCode::CompareImplTypeObligation { trait_item_def_id, .. } => {
+                let item_name = self.tcx.item_name(trait_item_def_id);
                 let msg = format!(
                     "the requirement `{}` appears on the associated impl type `{}` but not on the \
                      corresponding associated trait type",
diff --git a/compiler/rustc_typeck/src/check/compare_method.rs b/compiler/rustc_typeck/src/check/compare_method.rs
index 3eadb3f2363..cbfd8747ecf 100644
--- a/compiler/rustc_typeck/src/check/compare_method.rs
+++ b/compiler/rustc_typeck/src/check/compare_method.rs
@@ -92,7 +92,6 @@ fn compare_predicate_entailment<'tcx>(
         impl_m_span,
         impl_m_hir_id,
         ObligationCauseCode::CompareImplMethodObligation {
-            item_name: impl_m.ident.name,
             impl_item_def_id: impl_m.def_id,
             trait_item_def_id: trait_m.def_id,
         },
@@ -1167,7 +1166,6 @@ fn compare_type_predicate_entailment<'tcx>(
         impl_ty_span,
         impl_ty_hir_id,
         ObligationCauseCode::CompareImplTypeObligation {
-            item_name: impl_ty.ident.name,
             impl_item_def_id: impl_ty.def_id,
             trait_item_def_id: trait_ty.def_id,
         },