Revert "Use an empty keyword list instead of nil for empty definitions"

This reverts commit 4477115.

Author: josevalim

lib/elixir/lib/kernel.ex

@@ -4104,7 +4104,7 @@ defmodule Kernel do
       end
 
   """
-  defmacro def(call, expr \\ []) do
+  defmacro def(call, expr \\ nil) do
     define(:def, call, expr, __CALLER__)
   end
 
@@ -4134,7 +4134,7 @@ defmodule Kernel do
       ** (UndefinedFunctionError) undefined function Foo.sum/2
 
   """
-  defmacro defp(call, expr \\ []) do
+  defmacro defp(call, expr \\ nil) do
     define(:defp, call, expr, __CALLER__)
   end
 
@@ -4162,7 +4162,7 @@ defmodule Kernel do
       end
 
   """
-  defmacro defmacro(call, expr \\ []) do
+  defmacro defmacro(call, expr \\ nil) do
     define(:defmacro, call, expr, __CALLER__)
   end
 
@@ -4178,7 +4178,7 @@ defmodule Kernel do
   naming and default arguments.
 
   """
-  defmacro defmacrop(call, expr \\ []) do
+  defmacro defmacrop(call, expr \\ nil) do
     define(:defmacrop, call, expr, __CALLER__)
   end
 
@@ -4673,7 +4673,7 @@ defmodule Kernel do
             macro_definition =
               case impls do
                 [] ->
-                  define(kind, call, [], env)
+                  define(kind, call, nil, env)
 
                 [guard] ->
                   quoted =

lib/elixir/src/elixir_bootstrap.erl

@@ -10,11 +10,11 @@
 'MACRO-@'(Caller, Tree) ->
   unless_loaded('MACRO-@', [Caller, Tree], fun() -> nil end).
 
-'MACRO-def'(Caller, Call) -> 'MACRO-def'(Caller, Call, []).
+'MACRO-def'(Caller, Call) -> 'MACRO-def'(Caller, Call, nil).
 'MACRO-def'(Caller, Call, Expr) -> define(Caller, def, Call, Expr).
 'MACRO-defp'(Caller, Call, Expr) -> define(Caller, defp, Call, Expr).
 
-'MACRO-defmacro'(Caller, Call) -> 'MACRO-defmacro'(Caller, Call, []).
+'MACRO-defmacro'(Caller, Call) -> 'MACRO-defmacro'(Caller, Call, nil).
 'MACRO-defmacro'(Caller, Call, Expr) -> define(Caller, defmacro, Call, Expr).
 'MACRO-defmacrop'(Caller, Call, Expr) -> define(Caller, defmacrop, Call, Expr).
 

lib/elixir/src/elixir_def.erl

@@ -212,7 +212,7 @@ run_with_location_change(File, #{file := File} = E, Callback) ->
 run_with_location_change(File, E, Callback) ->
   elixir_lexical:with_file(File, E, Callback).
 
-def_to_clauses(_Kind, Meta, Args, [], [], E) ->
+def_to_clauses(_Kind, Meta, Args, [], nil, E) ->
   check_args_for_function_head(Meta, Args, E),
   [];
 def_to_clauses(_Kind, Meta, Args, Guards, [{do, Body}], _E) ->

lib/iex/test/iex/helpers_test.exs

@@ -382,7 +382,7 @@ defmodule IEx.HelpersTest do
         "* def left == right\n\n  @spec term() == term() :: boolean()\n\nguard: true\n\nReturns `true` if the two terms are equal.\n\n"
 
       def_h =
-        "* defmacro def(call, expr \\\\ [])\n\nDefines a public function with the given name and body."
+        "* defmacro def(call, expr \\\\ nil)\n\nDefines a public function with the given name and body."
 
       assert capture_io(fn -> h(IEx.Helpers.pwd() / 0) end) =~ pwd_h
       assert capture_io(fn -> h(IEx.Helpers.c() / 2) end) =~ c_h