From 2cc61eebb7f1677af2a20f76fb1411ed40f6901b Mon Sep 17 00:00:00 2001
From: Jeffrey Seyfried <jeffrey.seyfried@gmail.com>
Date: Thu, 2 Feb 2017 07:01:15 +0000
Subject: Allow using inert attributes from `proc_macro_derive`s with
 `#![feature(proc_macro)]`.

---
 src/libsyntax_ext/deriving/custom.rs | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

(limited to 'src/libsyntax_ext')

diff --git a/src/libsyntax_ext/deriving/custom.rs b/src/libsyntax_ext/deriving/custom.rs
index 974e86a5741..a7e2d82bb97 100644
--- a/src/libsyntax_ext/deriving/custom.rs
+++ b/src/libsyntax_ext/deriving/custom.rs
@@ -107,12 +107,10 @@ impl MultiItemModifier for ProcMacroDerive {
             }
         });
 
-        let mut res = vec![Annotatable::Item(item)];
         // Reassign spans of all expanded items to the input `item`
         // for better errors here.
-        res.extend(new_items.into_iter().flat_map(|item| {
-            ChangeSpan { span: span }.fold_item(item)
-        }).map(Annotatable::Item));
-        res
+        new_items.into_iter().map(|item| {
+            Annotatable::Item(ChangeSpan { span: span }.fold_item(item).expect_one(""))
+        }).collect()
     }
 }
-- 
cgit 1.4.1-3-g733a5