Add Compiler.reenable/1 to reenable compilers

Author: am-kantox

lib/mix/lib/mix/task.compiler.ex

@@ -175,18 +175,7 @@ defmodule Mix.Task.Compiler do
   """
   @callback clean() :: any
 
-  @doc """
-  A compiler task (as well as a regular task) may return a list of
-  dependent tasks if they are to be re-enabled when this task gets
-  re-enabled.
-
-  For instance, if task `"foo"` executes `"bar"` with
-  `Mix.Task.run("bar")` from `run/1`, this method should be
-  implemented to return `["bar"]`.
-  """
-  @callback depends_on :: [binary]
-
-  @optional_callbacks clean: 0, manifests: 0, depends_on: 0
+  @optional_callbacks clean: 0, manifests: 0
 
   @doc """
   Adds a callback that runs after a given compiler.
@@ -323,4 +312,33 @@ defmodule Mix.Task.Compiler do
 
     Mix.Sync.PubSub.broadcast(build_path, lazy_message)
   end
+
+  @doc """
+  Reenables given compilers so they can be executed again down the stack.
+
+  If an umbrella project reenables compilers, they are re-enabled for all
+  child projects.
+
+  Default is `[]`, for none compilers to be reenabled.
+  This task always re-enables `"compiler.all"`.
+  """
+  @spec reenable([{:compilers, compilers}]) :: :ok when compilers: :all | [Mix.Task.task_name()]
+  def reenable(opts \\ []) do
+    if not Keyword.keyword?(opts) do
+      IO.warn(
+        "Mix.Task.Compiler.reenable/1 expects a keyword list " <>
+          "as an argument with compilers: [compiler()], " <>
+          "reenabling no compiler"
+      )
+    else
+      compilers =
+        case Keyword.get(opts, :compilers, []) do
+          :all -> Mix.Tasks.Compile.compilers()
+          list when is_list(list) -> list
+        end
+
+      Enum.each(["loadpaths", "compile", "compile.all"], &Mix.Task.reenable(&1))
+      Enum.each(compilers, &Mix.Task.reenable("compile.#{&1}"))
+    end
+  end
 end

lib/mix/lib/mix/task.ex

@@ -131,18 +131,6 @@ defmodule Mix.Task do
   """
   @callback run(command_line_args :: [binary]) :: any
 
-  @doc """
-  A task may return a list of dependent tasks
-  if they are to be re-enabled when this task gets re-enabled.
-
-  For instance, if task `"foo"` executes `"bar"` with
-  `Mix.Task.run("bar")` from `run/1`, this method should be implemented
-  to return `["bar"]`.
-  """
-  @callback depends_on :: [binary]
-
-  @optional_callbacks depends_on: 0
-
   @doc false
   defmacro __using__(_opts) do
     quote do
@@ -630,20 +618,8 @@ defmodule Mix.Task do
   end
 
   def reenable(task) when is_binary(task) do
-    module = get(task)
-
-    # it’s safe against `no_return` because otherwise `run/1`
-    #   would be `no_return` as well
-    if module && function_exported?(module, :depends_on, 0) do
-      Enum.each(module.depends_on(), &reenable/1)
-    end
-
-    do_reenable(task, module)
-  end
-
-  defp do_reenable(task, module) do
     proj = Mix.Project.get()
-    recursive = module && recursive(module)
+    recursive = (module = get(task)) && recursive(module)
 
     Mix.TasksServer.delete_many([{:task, task, proj}, {:alias, task, proj}])
 

lib/mix/lib/mix/tasks/compile.all.ex

@@ -89,14 +89,6 @@ defmodule Mix.Tasks.Compile.All do
     result
   end
 
-  @impl true
-  @doc false
-  def depends_on do
-    Mix.Project.config()
-    |> Mix.Tasks.Compile.compilers()
-    |> Enum.map(&"compile.#{&1}")
-  end
-
   defp compile([], _, status, diagnostics) do
     {status, diagnostics}
   end

lib/mix/lib/mix/tasks/compile.ex

@@ -174,11 +174,6 @@ defmodule Mix.Tasks.Compile do
     {res, diagnostics}
   end
 
-  @impl true
-  def depends_on do
-    ["loadpaths", "compile.all"]
-  end
-
   defp format(expression, args) do
     :io_lib.format(expression, args) |> IO.iodata_to_binary()
   end

lib/mix/test/mix/tasks/compile_test.exs

@@ -123,9 +123,20 @@ defmodule Mix.Tasks.CompileTest do
       end
       """)
 
-      Mix.Task.reenable("compile")
-      assert {:ok, []} = Mix.Task.run("compile")
+      assert :ok = Mix.Task.reenable("compile")
+      assert {:noop, []} = Mix.Task.run("compile")
+      refute File.regular?("_build/dev/lib/sample/ebin/Elixir.Z.beam")
+
+      assert :ok = Mix.Task.Compiler.reenable()
+      assert {:noop, []} = Mix.Task.run("compile")
+      refute File.regular?("_build/dev/lib/sample/ebin/Elixir.Z.beam")
 
+      assert :ok = Mix.Task.Compiler.reenable(compilers: ["erlang"])
+      assert {:noop, []} = Mix.Task.run("compile")
+      refute File.regular?("_build/dev/lib/sample/ebin/Elixir.Z.beam")
+
+      assert :ok = Mix.Task.Compiler.reenable(compilers: ["elixir", "erlang"])
+      assert {:ok, []} = Mix.Task.run("compile")
       assert File.regular?("_build/dev/lib/sample/ebin/Elixir.Z.beam")
     end)
   end