Unify :empty_list and :list domains in maps

Author: gldubc

lib/elixir/lib/module/types/descr.ex

@@ -32,7 +32,6 @@ defmodule Module.Types.Descr do
 
   @domain_key_types [
     {:domain_key, :binary},
-    {:domain_key, :empty_list},
     {:domain_key, :integer},
     {:domain_key, :float},
     {:domain_key, :pid},
@@ -3031,7 +3030,7 @@ defmodule Module.Types.Descr do
   defp bitmap_to_domain_keys(bitmap) do
     [
       if((bitmap &&& @bit_binary) != 0, do: domain_key(:binary)),
-      if((bitmap &&& @bit_empty_list) != 0, do: domain_key(:empty_list)),
+      if((bitmap &&& @bit_empty_list) != 0, do: domain_key(:list)),
       if((bitmap &&& @bit_integer) != 0, do: domain_key(:integer)),
       if((bitmap &&& @bit_float) != 0, do: domain_key(:float)),
       if((bitmap &&& @bit_pid) != 0, do: domain_key(:pid)),

lib/elixir/test/elixir/module/types/descr_test.exs

@@ -1702,6 +1702,18 @@ defmodule Module.Types.DescrTest do
       t2 = closed_map([{domain_key(:tuple), float()}])
       t3 = union(t1, t2)
       assert map_get(t3, tuple()) == {:ok, number() |> nil_or_type()}
+
+      # Verify that empty_list() bitmap type maps to :list domain (not :empty_list domain)
+      map_with_list_domain = closed_map([{domain_key(:list), atom([:empty])}])
+
+      # empty_list() should access the :list domain
+      assert map_get(map_with_list_domain, empty_list()) == {:ok, atom([:empty]) |> nil_or_type()}
+
+      # non_empty_list() should also access the :list domain
+      assert map_get(map_with_list_domain, non_empty_list(integer())) == {:ok, atom([:empty]) |> nil_or_type()}
+
+      # list() should also access the :list domain
+      assert map_get(map_with_list_domain, list(integer())) == {:ok, atom([:empty]) |> nil_or_type()}
     end
 
     test "map_get with dynamic" do