Correct anchor for links to associated trait items

Author: mitaa

src/librustdoc/html/render.rs

@@ -2085,7 +2085,13 @@ fn render_assoc_item(w: &mut fmt::Formatter, meth: &clean::Item,
         let href = match link {
             AssocItemLink::Anchor => anchor,
             AssocItemLink::GotoSource(did) => {
-                href(did).map(|p| format!("{}{}", p.0, anchor)).unwrap_or(anchor)
+                // We're creating a link from an impl-item to the corresponding
+                // trait-item and need to map the anchored type accordingly.
+                let shortty = match shortty(it) {
+                    ItemType::Method => ItemType::TyMethod,
+                    s@_ => s,
+                };
+                href(did).map(|p| format!("{}#{}.{}", p.0, shortty, name)).unwrap_or(anchor)
             }
         };
         let vis_constness = match get_unstable_features_setting() {

src/test/rustdoc/issue-17476.rs

@@ -16,6 +16,6 @@ extern crate issue_17476;
 pub struct Foo;
 
 // @has issue_17476/struct.Foo.html \
-//      '//*[@href="http://example.com/issue_17476/trait.Foo.html#method.foo"]' \
+//      '//*[@href="http://example.com/issue_17476/trait.Foo.html#tymethod.foo"]' \
 //      'foo'
 impl issue_17476::Foo for Foo {}

src/test/rustdoc/issue-28478.rs

@@ -0,0 +1,27 @@
+// Copyright 2016 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.
+
+// @has issue_28478/trait.Bar.html
+pub trait Bar {
+    fn bar();
+}
+
+// @has issue_28478/struct.Foo.html
+pub struct Foo;
+
+impl Foo {
+    // @has - '//*[@href="#method.foo"]' 'foo'
+    pub fn foo() {}
+}
+
+impl Bar for Foo {
+    // @has - '//*[@href="../issue_28478/trait.Bar.html#tymethod.bar"]' 'bar'
+    fn bar() {}
+}