Also exclusive optional applications to Mix load path

Author: josevalim

lib/mix/lib/mix.ex

@@ -602,28 +602,42 @@ defmodule Mix do
   """
   @doc since: "1.15.0"
   def ensure_application!(app) when is_atom(app) do
-    ensure_application!(app, Mix.State.builtin_apps(), [])
+    ensure_application!(app, Mix.State.builtin_apps(), [], %{})
     :ok
   end
 
-  defp ensure_application!(app, builtin_apps, optional) do
-    case builtin_apps do
-      %{^app => path} ->
-        Code.prepend_path(path, cache: true)
-        Application.load(app)
-        optional = List.wrap(Application.spec(app, :optional_applications))
-
-        Application.spec(app, :applications)
-        |> List.wrap()
-        |> Enum.each(&ensure_application!(&1, builtin_apps, optional))
+  defp ensure_application!(app, builtin_apps, optional, seen) do
+    case seen do
+      %{^app => _} ->
+        seen
 
       %{} ->
-        unless app in optional do
-          Mix.raise(
-            "The application \"#{app}\" could not be found. This may happen if your " <>
-              "Operating System broke Erlang into multiple packages and may be fixed " <>
-              "by installing the missing \"erlang-dev\" and \"erlang-#{app}\" packages"
-          )
+        seen = Map.put(seen, app, true)
+
+        case builtin_apps do
+          %{^app => path} ->
+            Code.prepend_path(path, cache: true)
+            Application.load(app)
+
+            required = List.wrap(Application.spec(app, :applications))
+            optional = List.wrap(Application.spec(app, :optional_applications))
+
+            Enum.reduce(
+              required ++ optional,
+              seen,
+              &ensure_application!(&1, builtin_apps, optional, &2)
+            )
+
+          %{} ->
+            unless app in optional do
+              Mix.raise(
+                "The application \"#{app}\" could not be found. This may happen if your " <>
+                  "Operating System broke Erlang into multiple packages and may be fixed " <>
+                  "by installing the missing \"erlang-dev\" and \"erlang-#{app}\" packages"
+              )
+            end
+
+            seen
         end
     end
   end