Specify the kind of the item for E0121

compiler/rustc_hir/src/hir.rs

@@ -2815,6 +2815,27 @@ impl ItemKind<'_> {
             _ => return None,
         })
     }
+
+    pub fn descr(&self) -> &'static str {
+        match self {
+            ItemKind::ExternCrate(..) => "extern crate",
+            ItemKind::Use(..) => "`use` import",
+            ItemKind::Static(..) => "static item",
+            ItemKind::Const(..) => "constant item",
+            ItemKind::Fn(..) => "function",
+            ItemKind::Mod(..) => "module",
+            ItemKind::ForeignMod { .. } => "extern block",
+            ItemKind::GlobalAsm(..) => "global asm item",
+            ItemKind::TyAlias(..) => "type alias",
+            ItemKind::OpaqueTy(..) => "opaque type",
+            ItemKind::Enum(..) => "enum",
+            ItemKind::Struct(..) => "struct",
+            ItemKind::Union(..) => "union",
+            ItemKind::Trait(..) => "trait",
+            ItemKind::TraitAlias(..) => "trait alias",
+            ItemKind::Impl(..) => "implementation",
+        }
+    }
 }
 
 /// A reference from an trait to one of its associated items. This