Tweak E0271 wording

1 files changed, 6 insertions, 2 deletions

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 e9842b2cba5..df6ce2777cf 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -1866,10 +1866,14 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
 
         with_forced_trimmed_paths! {
             if Some(pred.projection_ty.def_id) == self.tcx.lang_items().fn_once_output() {
+                let fn_kind = self_ty.prefix_string(self.tcx);
+                let item = match self_ty.kind() {
+                    ty::FnDef(def, _) => self.tcx.item_name(*def).to_string(),
+                    _ => self_ty.to_string(),
+                };
                 Some(format!(
-                    "expected `{self_ty}` to be a {fn_kind} that returns `{expected_ty}`, but it \
+                    "expected `{item}` to be a {fn_kind} that returns `{expected_ty}`, but it \
                      returns `{normalized_ty}`",
-                    fn_kind = self_ty.prefix_string(self.tcx)
                 ))
             } else if Some(trait_def_id) == self.tcx.lang_items().future_trait() {
                 Some(format!(