Revert "Ensure project's Logger config is used when running Mix tasks (#9332)"

This reverts commit 78551c1.

Closes #9675.

Author: José Valim

lib/mix/lib/mix/cli.ex

@@ -1,8 +1,6 @@
 defmodule Mix.CLI do
   @moduledoc false
 
-  @compile {:no_warn_undefined, Logger.App}
-
   @doc """
   Runs Mix according to the command line arguments.
   """
@@ -78,8 +76,6 @@ defmodule Mix.CLI do
     try do
       ensure_no_slashes(name)
       Mix.Task.run("loadconfig")
-      # Restart Logger so it uses the configuration of the project.
-      if logger_configured?(), do: restart_logger()
       Mix.Task.run(name, args)
     rescue
       # We only rescue exceptions in the Mix namespace, all
@@ -95,18 +91,6 @@ defmodule Mix.CLI do
     end
   end
 
-  defp logger_configured? do
-    :logger in Mix.ProjectStack.config_apps()
-  end
-
-  defp restart_logger do
-    # Mix should not depend directly on Logger, that's why we first check if it's loaded.
-    if Process.whereis(Logger) do
-      Logger.App.stop()
-      :ok = Logger.App.start()
-    end
-  end
-
   defp env_variable_activated?(name) do
     System.get_env(name) in ~w(1 true)
   end

lib/mix/lib/mix/tasks/app.start.ex

@@ -70,15 +70,25 @@ defmodule Mix.Tasks.App.Start do
       end
     end
 
-    unless "--no-start" in args do
-      apps = apps(config)
-
-      # Stop Logger if the application does not depend on it.
-      #
-      # Mix should not depend directly on Logger, that's why we first check if it's loaded.
-      if not logger_dependency?(apps) && Process.whereis(Logger), do: Logger.App.stop()
+    # Stop Logger when starting the application as it is
+    # up to the application to decide if it should be restarted
+    # or not.
+    #
+    # Mix should not depend directly on Logger so check that it's loaded.
+    logger = Process.whereis(Logger)
+
+    if logger do
+      Logger.App.stop()
+    end
 
-      start(apps, type(config, opts), "--no-validate-compile-env" not in args)
+    if "--no-start" in args do
+      # Start Logger again if the application won't be starting it
+      if logger do
+        :ok = Logger.App.start()
+      end
+    else
+      config = Mix.Project.config()
+      start(apps(config), type(config, opts), "--no-validate-compile-env" not in args)
 
       # If there is a build path, we will let the application
       # that owns the build path do the actual check
@@ -215,31 +225,6 @@ defmodule Mix.Tasks.App.Start do
     :ok
   end
 
-  defp logger_dependency?(apps), do: logger_dependency?(apps, [])
-
-  defp logger_dependency?([], _checked_apps) do
-    false
-  end
-
-  defp logger_dependency?([app | apps], checked_apps) do
-    deps =
-      List.wrap(Application.spec(app, :included_applications)) ++
-        List.wrap(Application.spec(app, :applications))
-
-    cond do
-      deps == [] ->
-        logger_dependency?(apps, [app | checked_apps])
-
-      :logger in deps ->
-        true
-
-      true ->
-        checked_apps = [app | checked_apps]
-        new_apps = (deps -- apps) -- checked_apps
-        logger_dependency?(apps ++ new_apps, checked_apps)
-    end
-  end
-
   defp load_protocol(file) do
     case file do
       "Elixir." <> _ ->

lib/mix/test/mix/cli_test.exs

@@ -67,45 +67,6 @@ defmodule Mix.CLITest do
     end)
   end
 
-  test "runs the task using the Logger configuration of the project", context do
-    in_tmp(context.test, fn ->
-      File.mkdir_p!("lib")
-
-      File.write!("mix.exs", """
-      defmodule MyProject do
-        use Mix.Project
-
-        def project do
-          [app: :my_project, version: "0.0.1"]
-        end
-      end
-      """)
-
-      File.mkdir_p!("config")
-
-      File.write!("config/config.exs", """
-      import Config
-
-      config :logger, :console, format: "TEST[$level] $message\n"
-      """)
-
-      File.write!("lib/hello.ex", """
-      defmodule Mix.Tasks.LogHello do
-        use Mix.Task
-
-        require Logger
-
-        def run(_) do
-          Logger.info("HELLO")
-        end
-      end
-      """)
-
-      contents = mix(~w[log_hello])
-      assert contents =~ "TEST[info] HELLO\n"
-    end)
-  end
-
   test "no task error", context do
     in_tmp(context.test, fn ->
       contents = mix(~w[no_task])