Ensure arithmetic constants are supported in function heads

Author: José Valim

lib/elixir/lib/kernel.ex

@@ -1046,7 +1046,7 @@ defmodule Kernel do
 
   """
   defmacro left + right do
-    quote do: :erlang.+(unquote(left), unquote(right))
+    quote do: __op__(:+, unquote(left), unquote(right))
   end
 
   @doc """
@@ -1059,7 +1059,7 @@ defmodule Kernel do
 
   """
   defmacro left - right do
-    quote do: :erlang.-(unquote(left), unquote(right))
+    quote do: __op__(:-, unquote(left), unquote(right))
   end
 
   @doc """
@@ -1100,7 +1100,7 @@ defmodule Kernel do
 
   """
   defmacro left * right do
-    quote do: :erlang.*(unquote(left), unquote(right))
+    quote do: __op__(:*, unquote(left), unquote(right))
   end
 
   @doc """
@@ -1117,7 +1117,7 @@ defmodule Kernel do
 
   """
   defmacro left / right do
-    quote do: :erlang./(unquote(left), unquote(right))
+    quote do: __op__(:/, unquote(left), unquote(right))
   end
 
   @doc """

lib/elixir/test/elixir/kernel/fn_test.exs

@@ -4,6 +4,13 @@ defmodule Kernel.FnTest do
   use ExUnit.Case, async: true
   import CompileAssertion
 
+  test "arithmetic constants on match" do
+    assert (fn 1 + 2 -> :ok end).(3)  == :ok
+    assert (fn 1 - 2 -> :ok end).(-1) == :ok
+    assert (fn -1 -> :ok end).(-1) == :ok
+    assert (fn +1 -> :ok end).(1)  == :ok
+  end
+
   test "clause with ^" do
     x = 1
     assert (fn ^x -> :ok; _ -> :error end).(1) == :ok