Call preserving_mtime just once, at the root compile task

Author: José Valim

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

@@ -53,7 +53,6 @@ defmodule Mix.Tasks.Compile.Elixir do
 
          [watch_exts: [:ex, :eex]]
 
-
   """
   def run(args) do
     { opts, _ } = OptionParser.parse(args, aliases: [q: :quick],
@@ -70,11 +69,8 @@ defmodule Mix.Tasks.Compile.Elixir do
     stale      = Mix.Utils.extract_stale(to_watch, [compile_path])
 
     if opts[:force] or stale != [] do
-      Mix.Utils.preserving_mtime(compile_path, fn ->
-        File.mkdir_p! compile_path
-        compile_files opts[:quick], project, compile_path, to_compile, stale
-      end)
-
+      File.mkdir_p! compile_path
+      compile_files opts[:quick], project, compile_path, to_compile, stale
       :ok
     else
       :noop

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

@@ -28,11 +28,8 @@ defmodule Mix.Tasks.Compile.Erlang do
     if files == [] do
       :noop
     else
-      Mix.Utils.preserving_mtime(compile_path, fn ->
-        File.mkdir_p! compile_path
-        compile_files project, files, compile_path
-      end)
-
+      File.mkdir_p! compile_path
+      compile_files project, files, compile_path
       :ok
     end
   end

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

@@ -62,18 +62,22 @@ defmodule Mix.Tasks.Compile do
 
   def run(args) do
     Mix.Task.run "loadpaths", args
+    compile_path = Mix.project[:compile_path]
 
-    changed = Enum.reduce get_compilers, false, fn(compiler, acc) ->
-      res = Mix.Task.run "compile.#{compiler}", args
-      acc or res != :noop
-    end
+    changed =
+      Mix.Utils.preserving_mtime(compile_path, fn ->
+        Enum.reduce get_compilers, false, fn(compiler, acc) ->
+          res = Mix.Task.run "compile.#{compiler}", args
+          acc or res != :noop
+        end
+      end)
 
     # If any of the tasks above returns something different
     # than :noop, it means they produced something, so we
     # touch the common target `compile_path`. Notice that
     # we choose :noop since it is also the value returned
     # by a task that we already invoked.
-    if changed, do: File.touch Mix.project[:compile_path]
+    if changed, do: File.touch compile_path
   end
 
   defp get_compilers do

lib/mix/lib/mix/tasks/run.ex

@@ -14,8 +14,8 @@ defmodule Mix.Tasks.Run do
   * `--require`, `-r` - Requires a file before running the command
   * `--parallel-require`, `-pr` - Requires a file in parallel
   * `--no-halt` - Does not halt the system after running the command
-  * `--no-compile` - do not compile even if files require compilation;
-  * `--no-start` - do not start applications after compilation;
+  * `--no-compile` - Do not compile even if files require compilation;
+  * `--no-start` - Do not start applications after compilation;
 
   ## Examples