---

yaml
---
r: 176057
b: refs/heads/try
c: 038aa0e
h: refs/heads/master
i:
  176055: 9d19ee7
v: v3

Author: flaper87

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: a530cc9706324ad44dba464d541a807eb5afdb08
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 777435990e0e91df6b72ce80c9b6fa485eeb5daa
-refs/heads/try: 921ba5a09fa66b0a50bfebee5430622d0d4f3065
+refs/heads/try: 038aa0e8e958a78f01f7a322e2465fd4488fa021
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

branches/try/src/librustc_typeck/check/wf.rs

@@ -76,6 +76,18 @@ impl<'ccx, 'tcx> CheckTypeWellFormedVisitor<'ccx, 'tcx> {
             ast::ItemImpl(_, ast::ImplPolarity::Positive, _, _, _, _) => {
                 self.check_impl(item);
             }
+            ast::ItemImpl(_, ast::ImplPolarity::Negative, _, Some(ref tref), _, _) => {
+                let trait_ref = ty::node_id_to_trait_ref(ccx.tcx, tref.ref_id);
+                match ccx.tcx.lang_items.to_builtin_kind(trait_ref.def_id) {
+                    Some(ty::BoundSend) | Some(ty::BoundSync) => {}
+                    Some(_) | None => {
+                        ccx.tcx.sess.span_err(
+                            item.span,
+                            format!("negative impls are currently \
+                                     allowed just for `Send` and `Sync`").as_slice())
+                    }
+                }
+            }
             ast::ItemFn(..) => {
                 self.check_item_type(item);
             }

branches/try/src/test/compile-fail/typeck-negative-impls-builtin.rs

@@ -0,0 +1,20 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(optin_builtin_traits)]
+
+struct TestType;
+
+trait TestTrait {}
+
+impl !TestTrait for TestType {}
+//~^ ERROR  negative impls are currently allowed just for `Send` and `Sync`
+
+fn main() {}