Rollup merge of #39589 - ollie27:rustdoc_impl_disambiguation, r=alexcrichton

rustdoc: Improve impl disambiguation

* Don't disambiguate if there are multiple impls for the same type.
* Disambiguate for impls of &Foo and &mut Foo.
* Don't try to disambiguate generic types.

[before](https://doc.rust-lang.org/nightly/std/ops/trait.Rem.html#implementors) [after](https://ollie27.github.io/rust_doc_test/std/ops/trait.Rem.html#implementors)

1 files changed, 40 insertions, 0 deletions

diff --git a/src/test/rustdoc/impl-disambiguation.rs b/src/test/rustdoc/impl-disambiguation.rs
new file mode 100644
index 00000000000..afe1daf5983
--- /dev/null
+++ b/src/test/rustdoc/impl-disambiguation.rs
@@ -0,0 +1,40 @@
+// 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.
+
+#![crate_name = "foo"]
+
+pub trait Foo {}
+
+pub struct Bar<T> { field: T }
+
+// @has foo/trait.Foo.html '//*[@class="item-list"]//code' \
+//     "impl Foo for Bar<u8>"
+impl Foo for Bar<u8> {}
+// @has foo/trait.Foo.html '//*[@class="item-list"]//code' \
+//     "impl Foo for Bar<u16>"
+impl Foo for Bar<u16> {}
+// @has foo/trait.Foo.html '//*[@class="item-list"]//code' \
+//     "impl<'a> Foo for &'a Bar<u8>"
+impl<'a> Foo for &'a Bar<u8> {}
+
+pub mod mod1 {
+    pub struct Baz {}
+}
+
+pub mod mod2 {
+    pub enum Baz {}
+}
+
+// @has foo/trait.Foo.html '//*[@class="item-list"]//code' \
+//     "impl Foo for foo::mod1::Baz"
+impl Foo for mod1::Baz {}
+// @has foo/trait.Foo.html '//*[@class="item-list"]//code' \
+//     "impl<'a> Foo for &'a foo::mod2::Baz"
+impl<'a> Foo for &'a mod2::Baz {}