Deprecate Module.function/3

Author: José Valim

CHANGELOG.md

@@ -16,6 +16,7 @@
   * [Path] Do not normalize paths in `Path.join/2` as normalization is beyond the scope of such function
 
 * Deprecations
+  * [Module] `Module.function/3` is deprecated, please use `:erlang.make_fun/3` instead
 
 * Backwards incompatible changes
 

lib/elixir/lib/module.ex

@@ -476,15 +476,7 @@ defmodule Module do
     :elixir_aliases.safe_concat([left, right])
   end
 
-  @doc """
-  Gets an anonymous function from the given module, function
-  and arity. The module and function are not verified to exist.
-
-      iex> fun = Module.function(Kernel, :is_atom, 1)
-      iex> fun.(:hello)
-      true
-
-  """
+  @doc false
   def function(mod, fun, arity) do
     :erlang.make_fun(mod, fun, arity)
   end

lib/elixir/src/elixir_dispatch.erl

@@ -522,5 +522,7 @@ deprecation_message(Warning, Message) ->
     Message -> Warning ++ ", " ++ Message
   end.
 
+deprecation('Elixir.Module', 'function', 3) ->
+  "use :erlang.make_fun/3";
 deprecation(_, _, _) ->
   false.

lib/elixir/test/elixir/module_test.exs

@@ -240,9 +240,4 @@ defmodule ModuleTest do
       assert Module.definitions_in(__MODULE__, :defp) == []
     end
   end
-
-  test :function do
-    assert Module.function(:erlang, :atom_to_list, 1).(:hello) == 'hello'
-    assert is_function Module.function(This, :also_works, 0)
-  end
 end

lib/logger/lib/logger/formatter.ex

@@ -81,7 +81,7 @@ defmodule Logger.Formatter do
   """
 
   def format({mod, fun}, level, msg, ts, md) do
-    Module.function(mod, fun, 4).(level, msg, ts, md)
+    apply(mod, fun, [level, msg, ts, md])
   end
 
   def format(config, level, msg, ts, md) do