remove unused function argument

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -315,8 +315,6 @@ pub fn emit_inference_failure_err(
         body_id: Option<hir::BodyId>,
         failure_span: Span,
         arg: GenericArg<'tcx>,
-        // FIXME(#94483): Either use this or remove it.
-        _impl_candidates: Vec<ty::TraitRef<'tcx>>,
         error_code: TypeAnnotationNeeded,
         should_label_span: bool,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1980,7 +1980,6 @@ fn maybe_report_ambiguity(
                             body_id,
                             span,
                             trait_ref.self_ty().skip_binder().into(),
-                            vec![],
                             ErrorCode::E0282,
                             false,
                         )
@@ -2005,19 +2004,7 @@ fn maybe_report_ambiguity(
                 let subst = data.trait_ref.substs.iter().find(|s| s.has_infer_types_or_consts());
 
                 let mut err = if let Some(subst) = subst {
-                    let impl_candidates = self
+                    self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0283, true)
-                        .find_similar_impl_candidates(trait_ref)
-                        .into_iter()
-                        .map(|candidate| candidate.trait_ref)
-                        .collect();
-                    self.emit_inference_failure_err(
-                        body_id,
-                        span,
-                        subst,
-                        impl_candidates,
-                        ErrorCode::E0283,
-                        true,
-                    )
                 } else {
                     struct_span_err!(
                         self.tcx.sess,
@@ -2117,7 +2104,7 @@ fn maybe_report_ambiguity(
                     return;
                 }
 
-                self.emit_inference_failure_err(body_id, span, arg, vec![], ErrorCode::E0282, false)
+                self.emit_inference_failure_err(body_id, span, arg, ErrorCode::E0282, false)
             }
 
             ty::PredicateKind::Subtype(data) => {
@@ -2131,14 +2118,7 @@ fn maybe_report_ambiguity(
                 let SubtypePredicate { a_is_expected: _, a, b } = data;
                 // both must be type variables, or the other would've been instantiated
                 assert!(a.is_ty_var() && b.is_ty_var());
-                self.emit_inference_failure_err(
+                self.emit_inference_failure_err(body_id, span, a.into(), ErrorCode::E0282, true)
-                    body_id,
-                    span,
-                    a.into(),
-                    vec![],
-                    ErrorCode::E0282,
-                    true,
-                )
             }
             ty::PredicateKind::Projection(data) => {
                 if predicate.references_error() || self.is_tainted_by_errors() {
@@ -2155,7 +2135,6 @@ fn maybe_report_ambiguity(
                         body_id,
                         span,
                         subst,
-                        vec![],
                         ErrorCode::E0284,
                         true,
                     );

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -1538,14 +1538,7 @@ pub fn structurally_resolved_type(&self, sp: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
             ty
         } else {
             if !self.is_tainted_by_errors() {
-                self.emit_inference_failure_err(
+                self.emit_inference_failure_err((**self).body_id, sp, ty.into(), E0282, true)
-                    (**self).body_id,
-                    sp,
-                    ty.into(),
-                    vec![],
-                    E0282,
-                    true,
-                )
                     .emit();
             }
             let err = self.tcx.ty_error();

compiler/rustc_typeck/src/check/writeback.rs

@@ -692,7 +692,6 @@ fn report_type_error(&self, t: Ty<'tcx>) {
                     Some(self.body.id()),
                     self.span.to_span(self.tcx),
                     t.into(),
-                    vec![],
                     E0282,
                     false,
                 )
@@ -707,7 +706,6 @@ fn report_const_error(&self, c: ty::Const<'tcx>) {
                     Some(self.body.id()),
                     self.span.to_span(self.tcx),
                     c.into(),
-                    vec![],
                     E0282,
                     false,
                 )