refactor with map

Author: lengyijun

clippy_lints/src/borrow_deref_ref.rs

@@ -91,19 +91,20 @@ impl LateLintPass<'_> for BorrowDerefRef {
 
                         // has deref trait -> give 2 help
                         // doesn't have deref trait -> give 1 help
-                        if let Some(deref_trait_id) = cx.tcx.lang_items().deref_trait(){
-                            if !implements_trait(cx, inner_ty, deref_trait_id, &[]) {
-                                return;
+                        match cx.tcx.lang_items()
+                                .deref_trait()
+                                .map(|deref_trait_id| implements_trait(cx, inner_ty, deref_trait_id, &[]) ) {
+                            Some(false) => {}
+                            _ => {
+                                diag.help(
+                                    &format!(
+                                        "consider using `&**{}` if you would like to deref",
+                                        &snippet_opt(cx, deref_target.span).unwrap(),
+                                     )
+                                );
                             }
                         }
 
-                        diag.help(
-                            &format!(
-                                "consider using `&**{}` if you would like to deref",
-                                &snippet_opt(cx, deref_target.span).unwrap(),
-                             )
-                        );
-
                     }
                 );