From 01d24297eb6fe16abdf7869c60519650e3490faf Mon Sep 17 00:00:00 2001
From: Flavio Percoco <flaper87@gmail.com>
Date: Wed, 11 Mar 2015 01:51:50 +0100
Subject: [PATCH] Feature gate defaulted traits

---
 src/libsyntax/feature_gate.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 0a9980c89252..f5e891a9dd64 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -563,6 +563,13 @@ impl<'a, 'v> Visitor<'v> for PostExpansionVisitor<'a> {
                 }
             }
 
+            ast::ItemDefaultImpl(..) => {
+                self.gate_feature("optin_builtin_traits",
+                                  i.span,
+                                  "default trait implementations are experimental \
+                                   and possibly buggy");
+            }
+
             ast::ItemImpl(_, polarity, _, _, _, _) => {
                 match polarity {
                     ast::ImplPolarity::Negative => {