Change List.Chars.to_charlist to return empty list when given nil (#9299)

2 files changed, 8 insertions, 0 deletions

diff --git a/lib/elixir/lib/list/chars.ex b/lib/elixir/lib/list/chars.ex
index e9813a123..65ab3a906 100644
--- a/lib/elixir/lib/list/chars.ex
+++ b/lib/elixir/lib/list/chars.ex
@@ -24,6 +24,8 @@ defprotocol List.Chars do
 end
 
 defimpl List.Chars, for: Atom do
+  def to_charlist(nil), do: ''
+
   def to_charlist(atom), do: Atom.to_charlist(atom)
 end
 
diff --git a/lib/elixir/test/elixir/list/chars_test.exs b/lib/elixir/test/elixir/list/chars_test.exs
index 9f878c709..50679ccef 100644
--- a/lib/elixir/test/elixir/list/chars_test.exs
+++ b/lib/elixir/test/elixir/list/chars_test.exs
@@ -6,6 +6,12 @@ defmodule List.Chars.AtomTest do
   test "basic" do
     assert to_charlist(:foo) == 'foo'
   end
+
+  test "true false nil" do
+    assert to_charlist(false) == 'false'
+    assert to_charlist(true) == 'true'
+    assert to_charlist(nil) == ''
+  end
 end
 
 defmodule List.Chars.BitStringTest do