Fix a bad hint

Author: camsteffen

compiler/rustc_hir_typeck/src/demand.rs

@@ -1196,6 +1196,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let hir::Node::Expr(parent_expr) = self.tcx.parent_hir_node(expr.hir_id) else {
             return;
         };
+        if parent_expr.span.desugaring_kind().is_some() {
+            return;
+        }
         enum CallableKind {
             Function,
             Method,