1 files changed, 30 insertions, 11 deletions
diff --git a/compiler/rustc_typeck/src/check/wfcheck.rs b/compiler/rustc_typeck/src/check/wfcheck.rs
index d9f9d9dafff..df9399c56c7 100644
--- a/compiler/rustc_typeck/src/check/wfcheck.rs
+++ b/compiler/rustc_typeck/src/check/wfcheck.rs
@@ -203,25 +203,41 @@ pub fn check_trait_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
 
     let encl_trait_hir_id = tcx.hir().get_parent_item(hir_id);
     let encl_trait = tcx.hir().expect_item(encl_trait_hir_id);
-    if [tcx.lang_items().fn_trait(), tcx.lang_items().fn_mut_trait()]
-        .contains(&Some(encl_trait.def_id.to_def_id()))
-        && trait_item.ident.name.to_ident_string() == "call"
+    let encl_trait_def_id = encl_trait.def_id.to_def_id();
+    let fn_lang_item_name = if Some(encl_trait_def_id) == tcx.lang_items().fn_trait() {
+        Some("fn")
+    } else if Some(encl_trait_def_id) == tcx.lang_items().fn_mut_trait() {
+        Some("fn_mut")
+    } else {
+        None
+    };
+
+    if let (Some(fn_lang_item_name), "call") =
+        (fn_lang_item_name, trait_item.ident.name.to_ident_string().as_str())
     {
         // We are looking at the `call` function of the `fn` or `fn_mut` lang item.
         // Do some rudimentary sanity checking to avoid an ICE later (issue #83471).
-        if let Some(method_sig @ hir::FnSig { decl, .. }) = method_sig {
+        if let Some(hir::FnSig { decl, span, .. }) = method_sig {
             if let &[self_ty, _] = &decl.inputs {
                 if !matches!(self_ty.kind, hir::TyKind::Rptr(_, _)) {
-                    tcx.sess.struct_span_err(
-                        self_ty.span,
-                        "first argument of `call` in `fn`/`fn_mut` lang item must be a reference",
-                    ).emit();
+                    tcx.sess
+                        .struct_span_err(
+                            self_ty.span,
+                            &format!(
+                                "first argument of `call` in `{}` lang item must be a reference",
+                                fn_lang_item_name
+                            ),
+                        )
+                        .emit();
                 }
             } else {
                 tcx.sess
                     .struct_span_err(
-                        method_sig.span,
-                        "`call` function in `fn`/`fn_mut` lang item takes exactly two arguments",
+                        *span,
+                        &format!(
+                            "`call` function in `{}` lang item takes exactly two arguments",
+                            fn_lang_item_name
+                        ),
                     )
                     .emit();
             }
@@ -229,7 +245,10 @@ pub fn check_trait_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
             tcx.sess
                 .struct_span_err(
                     trait_item.span,
-                    "`call` trait item in `fn`/`fn_mut` lang item must be a function",
+                    &format!(
+                        "`call` trait item in `{}` lang item must be a function",
+                        fn_lang_item_name
+                    ),
                 )
                 .emit();
         }