Do not convert fun() into (... -> any()) and vice-versa in typespecs

Author: josevalim

lib/elixir/lib/code/typespec.ex

@@ -27,11 +27,6 @@ defmodule Code.Typespec do
     end
   end
 
-  def spec_to_quoted(name, {:type, anno, :fun, []}) when is_atom(name) do
-    meta = meta(anno)
-    {:"::", meta, [{name, meta, []}, quote(do: term)]}
-  end
-
   def spec_to_quoted(name, {:type, anno, :bounded_fun, [type, constrs]}) when is_atom(name) do
     meta = meta(anno)
     {:type, _, :fun, [{:type, _, :product, args}, result]} = type
@@ -317,10 +312,6 @@ defmodule Code.Typespec do
     [{:->, meta(anno), [[typespec_to_quoted(args)], typespec_to_quoted(result)]}]
   end
 
-  defp typespec_to_quoted({:type, anno, :fun, []}) do
-    typespec_to_quoted({:type, anno, :fun, [{:type, anno, :any}, {:type, anno, :any, []}]})
-  end
-
   defp typespec_to_quoted({:type, anno, :range, [left, right]}) do
     {:.., meta(anno), [typespec_to_quoted(left), typespec_to_quoted(right)]}
   end

lib/elixir/lib/kernel/typespec.ex

@@ -668,14 +668,7 @@ defmodule Kernel.Typespec do
        when is_list(args) do
     {args, state} = fn_args(meta, args, vars, caller, state)
     {spec, state} = typespec(return, vars, caller, state)
-
-    fun_args =
-      case [args, spec] do
-        [{:type, _, :any}, {:type, _, :any, []}] -> []
-        pair -> pair
-      end
-
-    {{:type, location(meta), :fun, fun_args}, state}
+    {{:type, location(meta), :fun, [args, spec]}, state}
   end
 
   # Handle type operator

lib/elixir/test/elixir/typespec_test.exs

@@ -710,7 +710,8 @@ defmodule TypespecTest do
           @type my_type :: (... -> any)
         end
 
-      assert [type: {:my_type, {:type, _, :fun, []}, []}] = types(bytecode)
+      assert [type: {:my_type, {:type, _, :fun, [{:type, _, :any}, {:type, _, :any, []}]}, []}] =
+               types(bytecode)
     end
 
     test "@type with a fun with multiple arguments and return type" do
@@ -1520,9 +1521,6 @@ defmodule TypespecTest do
             assert ast_string ==
                      "@type literal_struct_all_fields_key_type() :: %TypespecTest.SomeStruct{key: integer()}"
 
-          {:built_in_fun, _, _} ->
-            assert ast_string == "@type built_in_fun() :: (... -> any())"
-
           {:built_in_nonempty_list, _, _} ->
             assert ast_string == "@type built_in_nonempty_list() :: [...]"