From 943a794b9308a3998cbdc89cd1f4a61c67377ba7 Mon Sep 17 00:00:00 2001
From: Wojtek Mach <wojtek@wojtekmach.pl>
Date: Wed, 6 Dec 2017 18:01:18 +0100
Subject: [PATCH 1/2] Autolink Erlang typespecs

---
 lib/ex_doc/formatter/html/autolink.ex        | 17 +++++++++++++----
 test/ex_doc/formatter/html/autolink_test.exs | 11 +++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/lib/ex_doc/formatter/html/autolink.ex b/lib/ex_doc/formatter/html/autolink.ex
index aaa7596a7..9cd11b82f 100644
--- a/lib/ex_doc/formatter/html/autolink.ex
+++ b/lib/ex_doc/formatter/html/autolink.ex
@@ -67,7 +67,7 @@ defmodule ExDoc.Formatter.HTML.Autolink do
   """
   def all(modules, extension, extra_lib_dirs) do
     aliases = Enum.map modules, &(&1.module)
-    lib_dirs = extra_lib_dirs ++ elixir_lib_dirs()
+    lib_dirs = extra_lib_dirs ++ elixir_lib_dirs() ++ erlang_lib_dirs()
     modules
     |> Enum.map(&Task.async(fn -> process_module(&1, modules, aliases, extension, lib_dirs) end))
     |> Enum.map(&Task.await(&1, :infinity))
@@ -141,7 +141,7 @@ defmodule ExDoc.Formatter.HTML.Autolink do
   Converts the given `ast` to string while linking the locals
   given by `typespecs` as HTML.
   """
-  def typespec(ast, typespecs, aliases, lib_dirs \\ elixir_lib_dirs()) do
+  def typespec(ast, typespecs, aliases, lib_dirs \\ elixir_lib_dirs() ++ erlang_lib_dirs()) do
     if formatter_available?() do
       format_typespec(ast, typespecs, aliases, lib_dirs)
     else
@@ -246,8 +246,7 @@ defmodule ExDoc.Formatter.HTML.Autolink do
           alias = expand_alias(alias)
 
           if source = get_source(alias, aliases, lib_dirs) do
-            n = enc_h("#{name}")
-            url = "#{source}#{enc_h(inspect alias)}.html#t:#{n}/#{length(args)}"
+            url = remote_url(source, alias, name, args)
             string = format_typespec_form(form, url)
             put_placeholder(form, string, placeholders)
           else
@@ -263,6 +262,16 @@ defmodule ExDoc.Formatter.HTML.Autolink do
     |> replace_placeholders(placeholders)
   end
 
+  defp remote_url(@erlang_docs = source, module, name, _args) do
+    module = enc_h("#{module}")
+    name = enc_h("#{name}")
+    "#{source}#{module}.html#type-#{name}"
+  end
+  defp remote_url(source, alias, name, args) do
+    name = enc_h("#{name}")
+    "#{source}#{enc_h(inspect alias)}.html#t:#{name}/#{length(args)}"
+  end
+
   defp format_typespec_form(form, url) do
     string = Macro.to_string(form)
     {string_to_link, _string_with_parens} = split_string_to_link(string)
diff --git a/test/ex_doc/formatter/html/autolink_test.exs b/test/ex_doc/formatter/html/autolink_test.exs
index 9638a7d57..0dd25c9c4 100644
--- a/test/ex_doc/formatter/html/autolink_test.exs
+++ b/test/ex_doc/formatter/html/autolink_test.exs
@@ -305,6 +305,17 @@ defmodule ExDoc.Formatter.HTML.AutolinkTest do
            ~s[<a href=\"typespecs.html#built-in-types\">term</a>()]
   end
 
+  test "autolink Erlang types in typespecs" do
+    assert Autolink.typespec(quote(do: :sets.set()), [], []) ==
+           ~s[<a href=\"#{@erlang_docs}sets.html#type-set\">:sets.set</a>()]
+
+    assert Autolink.typespec(quote(do: :sets.set(foo())), [], []) ==
+           ~s[<a href=\"#{@erlang_docs}sets.html#type-set\">:sets.set</a>(foo())]
+
+    assert Autolink.typespec(quote(do: :sets.set(foo())), [foo: 0], []) ==
+           ~s[<a href=\"#{@erlang_docs}sets.html#type-set\">:sets.set</a>(<a href=\"#t:foo/0\">foo</a>())]
+  end
+
   test "autolink shared aliases in typespecs" do
     assert Autolink.typespec(quote(do: Foo.t), [], [Foo]) ==
            ~s[<a href="Foo.html#t:t/0">Foo.t</a>()]

From 22048e30da6f34bb893bddc024fcee563961d9ee Mon Sep 17 00:00:00 2001
From: Wojtek Mach <wojtek@wojtekmach.pl>
Date: Wed, 6 Dec 2017 19:03:55 +0100
Subject: [PATCH 2/2] Update test

---
 test/ex_doc/formatter/html/templates_test.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/ex_doc/formatter/html/templates_test.exs b/test/ex_doc/formatter/html/templates_test.exs
index 520fa9802..24c966f66 100644
--- a/test/ex_doc/formatter/html/templates_test.exs
+++ b/test/ex_doc/formatter/html/templates_test.exs
@@ -261,7 +261,7 @@ defmodule ExDoc.Formatter.HTML.TemplatesTest do
       ~S[<a href="TypesAndSpecs.Sub.html#t:t/0">TypesAndSpecs.Sub.t</a>(), ] <>
       ~S[<a href="#t:opaque/0">opaque</a>(), :ok | :error}]
 
-    ref_html = ~s[ref() :: {:binary.part(), <a href="#t:public/1">public</a>(#{any})}]
+    ref_html = ~s[ref() :: {<a href="http://www.erlang.org/doc/man/binary.html#type-part">:binary.part</a>(), <a href="#t:public/1">public</a>(#{any})}]
 
     assert content =~ ~s[<a href="#t:public/1">public(t)</a>]
     refute content =~ ~s[<a href="#t:private/0">private</a>]