Display negative traits implementation

src/librustdoc/html/render.rs

@@ -3613,18 +3613,24 @@ fn sidebar_assoc_items(it: &clean::Item) -> String {
             }
             let mut links = HashSet::new();
             let ret = v.iter()
-                       .filter_map(|i| if let Some(ref i) = i.inner_impl().trait_ {
-                           let i_display = format!("{:#}", i);
-                           let out = Escape(&i_display);
-                           let encoded = small_url_encode(&format!("{:#}", i));
-                           let generated = format!("<a href=\"#impl-{}\">{}</a>", encoded, out);
-                           if !links.contains(&generated) && links.insert(generated.clone()) {
-                               Some(generated)
+                       .filter_map(|i| {
+                           let is_negative_impl = is_negative_impl(i.inner_impl());
+                           if let Some(ref i) = i.inner_impl().trait_ {
+                               let i_display = format!("{:#}", i);
+                               let out = Escape(&i_display);
+                               let encoded = small_url_encode(&format!("{:#}", i));
+                               let generated = format!("<a href=\"#impl-{}\">{}{}</a>",
+                                                       encoded,
+                                                       if is_negative_impl { "!" } else { "" },
+                                                       out);
+                               if !links.contains(&generated) && links.insert(generated.clone()) {
+                                   Some(generated)
+                               } else {
+                                   None
+                               }
                            } else {
                                None
                            }
-                       } else {
-                           None
                        })
                        .collect::<String>();
             if !ret.is_empty() {
@@ -3671,6 +3677,10 @@ fn extract_for_impl_name(item: &clean::Item) -> Option<(String, String)> {
     }
 }
 
+fn is_negative_impl(i: &clean::Impl) -> bool {
+    i.polarity == Some(clean::ImplPolarity::Negative)
+}
+
 fn sidebar_trait(fmt: &mut fmt::Formatter, it: &clean::Item,
                  t: &clean::Trait) -> fmt::Result {
     let mut sidebar = String::new();

src/test/rustdoc/negative-impl-sidebar.rs

@@ -0,0 +1,19 @@
+// Copyright 2017 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)]
+#![crate_name = "foo"]
+
+pub struct Foo;
+
+// @has foo/struct.Foo.html
+// @has - '//*[@class="sidebar-title"][@href="#implementations"]' 'Trait Implementations'
+// @has - '//*[@class="sidebar-links"]/a' '!Sync'
+impl !Sync for Foo {}