Autolink basic/built-in types and special forms in docs

lib/ex_doc/formatter/html/autolink.ex

@@ -62,6 +62,10 @@ defmodule ExDoc.Formatter.HTML.Autolink do
     timeout: 0
   ]
 
+  @basic_type_strings (for {f, a} <- @basic_types, do: "t:#{f}/#{a}")
+  @built_in_type_strings (for {f, a} <- @built_in_types, do: "t:#{f}/#{a}")
+  @special_form_strings (for {f, a} <- Kernel.SpecialForms.__info__(:macros), do: "#{f}/#{a}")
+
   @doc """
   Receives a list of module nodes and autolink all docs and typespecs.
   """
@@ -94,15 +98,15 @@ defmodule ExDoc.Formatter.HTML.Autolink do
     moduledoc =
       if module.doc do
         module.doc
-        |> local_doc(locals)
+        |> local_doc(locals, extension, lib_dirs)
         |> project_doc(modules, module.id, extension, lib_dirs)
       end
 
     docs = for module_node <- module.docs do
       doc =
         if module_node.doc do
           module_node.doc
-          |> local_doc(locals)
+          |> local_doc(locals, extension, lib_dirs)
           |> project_doc(modules, module.id, extension, lib_dirs)
         end
       %{module_node | doc: doc}
@@ -112,7 +116,7 @@ defmodule ExDoc.Formatter.HTML.Autolink do
       doc =
         if module_node.doc do
           module_node.doc
-          |> local_doc(locals)
+          |> local_doc(locals, extension, lib_dirs)
           |> project_doc(modules, module.id, extension, lib_dirs)
         end
       %{module_node | doc: doc}
@@ -339,15 +343,29 @@ defmodule ExDoc.Formatter.HTML.Autolink do
   or trailing `]`, e.g. `[my link link/1 is here](url)`, the fun/arity
   will get translated to the new href of the function.
   """
-  def local_doc(bin, locals) when is_binary(bin) do
+  def local_doc(bin, locals, extension \\ ".html", lib_dirs \\ elixir_lib_dirs()) when is_binary(bin) do
     fun_re = Regex.source(~r{(([ct]:)?([a-z_]+[A-Za-z_\d]*[\\?\\!]?|[\{\}=&\\|\\.<>~*^@\\+\\%\\!-]+)/\d+)})
     regex = ~r{(?<!\[)`\s*(#{fun_re})\s*`(?!\])}
+    elixir_doc = get_source(Kernel, [], lib_dirs)
+
     Regex.replace(regex, bin, fn all, match ->
-      if match in locals do
-        {prefix, _, function, arity} = split_function(match)
-        "[`#{function}/#{arity}`](##{prefix}#{enc_h function}/#{arity})"
-      else
-        all
+      {prefix, _, function, arity} = split_function(match)
+
+      cond do
+        match in locals ->
+          "[`#{function}/#{arity}`](##{prefix}#{enc_h function}/#{arity})"
+
+        match in @basic_type_strings ->
+          "[`#{function}/#{arity}`](#{elixir_doc}#{@basic_types_page})"
+
+        match in @built_in_type_strings ->
+          "[`#{function}/#{arity}`](#{elixir_doc}#{@built_in_types_page})"
+
+        match in @special_form_strings ->
+          "[`#{function}/#{arity}`](#{elixir_doc}Kernel.SpecialForms#{extension}##{prefix}#{enc_h function}/#{arity})"
+
+        true ->
+          all
       end
     end)
   end
@@ -406,8 +424,10 @@ defmodule ExDoc.Formatter.HTML.Autolink do
       cond do
         match in project_funs ->
           "[`#{module}.#{function}/#{arity}`](#{module}#{extension}##{prefix}#{enc_h function}/#{arity})"
+
         doc = lib_dirs_to_doc("Elixir." <> module, lib_dirs) ->
           "[`#{module}.#{function}/#{arity}`](#{doc}#{module}.html##{prefix}#{enc_h function}/#{arity})"
+
         true ->
           all
       end

test/ex_doc/formatter/html/autolink_test.exs

@@ -34,6 +34,13 @@ defmodule ExDoc.Formatter.HTML.AutolinkTest do
     # links to types without arity don't work
     assert Autolink.local_doc("`t:my_type`", ["t:my_type/0"]) == "`t:my_type`"
   end
+  test "autolink to basic and built-in types" do
+    assert Autolink.local_doc("`t:atom/0`", []) ==
+      "[`atom/0`](#{@elixir_docs}elixir/typespecs.html#basic-types)"
+
+    assert Autolink.local_doc("`t:term/0`", []) ==
+      "[`term/0`](#{@elixir_docs}elixir/typespecs.html#built-in-types)"
+  end
 
   test "autolink doesn't create links for undefined functions in docs" do
     assert Autolink.local_doc("`example/1`", ["example/2"]) == "`example/1`"
@@ -54,6 +61,11 @@ defmodule ExDoc.Formatter.HTML.AutolinkTest do
     assert Autolink.local_doc("`{}/1`", ["{}/1"]) === "[`{}/1`](#%7B%7D/1)"
   end
 
+  test "autolink creates links for Kernel special forms" do
+    assert Autolink.local_doc("`<<>>/1`", []) ===
+           "[`<<>>/1`](#{@elixir_docs}elixir/Kernel.SpecialForms.html#%3C%3C%3E%3E/1)"
+  end
+
   # elixir_functions
 
   test "autolink functions Module.fun/arity in docs" do

test/ex_doc/formatter/html/templates_test.exs

@@ -271,6 +271,8 @@ defmodule ExDoc.Formatter.HTML.TemplatesTest do
     assert content =~ ~s[A public type]
     assert content =~ ~s[add(#{integer}, <a href="#t:opaque/0">opaque</a>()) :: #{integer}]
     refute content =~ ~s[minus(#{integer}, #{integer}) :: #{integer}]
+    assert content =~ ~s[Basic type: <a href=\"https://hexdocs.pm/elixir/typespecs.html#basic-types\"><code class=\"inline\">atom/0</code></a>.]
+    assert content =~ ~s[Special form: <a href=\"https://hexdocs.pm/elixir/Kernel.SpecialForms.html#import/2\"><code class=\"inline\">import/2</code></a>.]
   end
 
   test "module_page outputs summaries" do

test/fixtures/types_and_specs.ex

@@ -5,6 +5,9 @@ defmodule TypesAndSpecs do
 
   @moduledoc """
   Types and tests fixture.
+
+  Basic type: `t:atom/0`.
+  Special form: `import/2`.
   """
 
   @typedoc "A public type"