From 928eedb0aaaaf126a726b2197e8bcbe93da95f3c Mon Sep 17 00:00:00 2001
From: JOE1994 <joseph942010@gmail.com>
Date: Sun, 19 Apr 2020 12:00:45 -0400
Subject: [PATCH] fix decode logic for 'AttrId' to be symmetric with encode
 logic

---
 src/librustc_ast/ast.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/librustc_ast/ast.rs b/src/librustc_ast/ast.rs
index ffee454dbac..f58a0c6deae 100644
--- a/src/librustc_ast/ast.rs
+++ b/src/librustc_ast/ast.rs
@@ -2218,8 +2218,8 @@ fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 }
 
 impl rustc_serialize::Decodable for AttrId {
-    fn decode<D: Decoder>(_: &mut D) -> Result<AttrId, D::Error> {
-        Ok(crate::attr::mk_attr_id())
+    fn decode<D: Decoder>(d: &mut D) -> Result<AttrId, D::Error> {
+        d.read_nil().map(|_| crate::attr::mk_attr_id())
     }
 }