Merge pull request #2164 from liveforeverx/fix_enum

fix matching on every map in Enum.into/2

Author: José Valim

lib/elixir/lib/enum.ex

@@ -838,7 +838,7 @@ defmodule Enum do
     list ++ to_list(collection)
   end
 
-  def into(collection, %{}) when is_list(collection) do
+  def into(collection, %{} = map) when is_list(collection) and (map_size(map) == 0) do
     :maps.from_list(collection)
   end
 

lib/elixir/test/elixir/enum_test.exs

@@ -187,6 +187,7 @@ defmodule EnumTest.List do
 
   test :into do
     assert Enum.into([a: 1, b: 2], %{}) == %{a: 1, b: 2}
+    assert Enum.into([a: 1, b: 2], %{c: 3}) == %{a: 1, b: 2, c: 3}
     assert Enum.into(%{a: 1, b: 2}, []) == [a: 1, b: 2]
     assert Enum.into([1, 2, 3], "numbers: ", &to_string/1) == "numbers: 123"
     assert Enum.into([1, 2, 3], fn