suggest to limit lifetime of temporary borrow with let

diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index 66737372bda37b2664d1be8629ac1e28dc943876..13eb47a041fa670008cc7cf517d8378e6ece138e 100644 (file)
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -2578,7 +2578,7 @@ fn note_obligation_cause_for_async_await(
             };
 
             span.push_span_label(original_span, message);
-            err.set_span(span);
+            err.set_span(span.clone());
 
             format!("is not {}", trait_name)
         } else {