Allow use of macros in alias

Author: sabiwara

lib/elixir/lib/kernel/typespec.ex

@@ -938,15 +938,15 @@ defmodule Kernel.Typespec do
 
   ## Helpers
 
-  # This is a backport of Macro.expand/2 because we want to expand
+  # This is a modified backport of Macro.expand/2 because we want to expand
   # aliases but we don't them to become compile-time references.
   defp expand_remote({:__aliases__, meta, list} = alias, env) do
     case :elixir_aliases.expand_or_concat(meta, list, env, true) do
       receiver when is_atom(receiver) ->
         receiver
 
       [head | tail] ->
-        case Macro.expand_once(head, env) do
+        case Macro.expand(head, env) do
           head when is_atom(head) ->
             :elixir_aliases.concat([head | tail])
 

lib/elixir/test/elixir/typespec_test.exs

@@ -849,6 +849,19 @@ defmodule TypespecTest do
       assert [{:atom, _, Keyword}, {:atom, _, :t}, [{:var, _, :value}]] = kw_with_value_args
     end
 
+    test "@type with macro in alias" do
+      bytecode =
+        test_module do
+          defmacro module() do
+            quote do: __MODULE__
+          end
+
+          @type my_type :: module().Foo
+        end
+
+      assert [type: {:my_type, {:atom, _, TypespecTest.TypespecSample.Foo}, []}] = types(bytecode)
+    end
+
     test "@type with a reserved signature" do
       assert_raise Kernel.TypespecError,
                    ~r"type required\/1 is a reserved type and it cannot be defined",