Sinplify mechanism for checking and handling locks

In particular, there is no need to pass :lockfile around deps.
We also remove the umbrella handling from the lock.

Author: José Valim

lib/mix/lib/mix/deps.ex

@@ -270,7 +270,11 @@ defmodule Mix.Deps do
         :outdated ->
           dep.status :lockoutdated
         :ok ->
-          dep
+          if vsn = old_elixir_lock(dep) do
+            dep.status({ :elixirlock, vsn })
+          else
+            dep
+          end
       end
     else
       dep
@@ -451,4 +455,11 @@ defmodule Mix.Deps do
       if is_binary(app), do: binary_to_atom(app), else: app
     end
   end
+
+  defp old_elixir_lock(Mix.Dep[opts: opts]) do
+    old_vsn = Mix.Deps.Lock.elixir_vsn(opts[:build])
+    if old_vsn && old_vsn != System.version do
+      old_vsn
+    end
+  end
 end

lib/mix/lib/mix/deps/lock.ex

@@ -9,40 +9,28 @@ defmodule Mix.Deps.Lock do
   @doc """
   Returns the manifest file for dependencies.
   """
-  def manifest do
-    Path.join(Mix.Project.manifest_path, @manifest)
+  def manifest(manifest_path // Mix.Project.manifest_path) do
+    Path.join(manifest_path, @manifest)
   end
 
   @doc """
   Touches the manifest timestamp and updates the elixir version.
   """
-  def touch do
-    manifest_path = Mix.Project.manifest_path
+  def touch(manifest_path // Mix.Project.manifest_path) do
     File.mkdir_p!(manifest_path)
     File.write!(Path.join(manifest_path, @manifest), System.version)
   end
 
   @doc """
   Returns the elixir lock version.
   """
-  def elixir_vsn do
-    unless Mix.Project.umbrella? do
-      case File.read(manifest) do
-        { :ok, contents } -> contents
-        { :error, _ } -> nil
-      end
+  def elixir_vsn(manifest_path // Mix.Project.manifest_path) do
+    case File.read(manifest(manifest_path)) do
+      { :ok, contents } -> contents
+      { :error, _ } -> nil
     end
   end
 
-  @doc """
-  Returns the lockfile path. In case this is a nested
-  dependencies, the lockfile will always point to the
-  parent project lockfile.
-  """
-  def lockfile do
-    Mix.project[:lockfile]
-  end
-
   @doc """
   Read the lockfile, returns a keyword list containing
   each app name and its current lock information.
@@ -72,4 +60,8 @@ defmodule Mix.Deps.Lock do
       touch
     end
   end
-end
+
+  defp lockfile do
+    Mix.project[:lockfile]
+  end
+end

lib/mix/lib/mix/deps/retriever.ex

@@ -139,7 +139,7 @@ defmodule Mix.Deps.Retriever do
 
   ## Fetching
 
-  defp mix_dep(Mix.Dep[opts: opts, app: app, status: status] = dep, config) do
+  defp mix_dep(Mix.Dep[opts: opts, app: app] = dep, config) do
     Mix.Deps.in_dependency(dep, config, fn _ ->
       config    = Mix.project
       umbrella? = Mix.Project.umbrella?
@@ -150,14 +150,12 @@ defmodule Mix.Deps.Retriever do
           Path.join(Mix.Project.compile_path(config), "#{app}.app")
         end
 
-      stat = cond do
-        vsn = old_elixir_lock() -> { :elixirlock, vsn }
-        req = old_elixir_req(config) -> { :elixirreq, req }
-        true -> status
+      if req = old_elixir_req(config) do
+        dep = dep.status({ :elixirreq, req })
       end
 
       opts = Keyword.put_new(opts, :app, app_path)
-      { dep.manager(:mix).opts(opts).status(stat).extra(umbrella: umbrella?), children }
+      { dep.manager(:mix).opts(opts).extra(umbrella: umbrella?), children }
     end)
   end
 
@@ -210,13 +208,6 @@ defmodule Mix.Deps.Retriever do
     end
   end
 
-  defp old_elixir_lock do
-    old_vsn = Mix.Deps.Lock.elixir_vsn
-    if old_vsn && old_vsn != System.version do
-      old_vsn
-    end
-  end
-
   defp old_elixir_req(config) do
     req = config[:elixir]
     if req && not Version.match?(System.version, req) do

lib/mix/lib/mix/project.ex

@@ -71,8 +71,7 @@ defmodule Mix.Project do
   @doc false
   def deps_config(config // config()) do
     [ build_path: build_path(config),
-      deps_path: deps_path(config),
-      lockfile: Path.expand(config[:lockfile]) ]
+      deps_path: deps_path(config) ]
   end
 
   @doc """

lib/mix/lib/mix/tasks/loadpaths.ex

@@ -38,8 +38,9 @@ defmodule Mix.Tasks.Loadpaths do
       end
     end
 
-    # Force recompile if we have a version mismatch
-    old_vsn = Mix.Deps.Lock.elixir_vsn
+    # Force recompile if we have a version mismatch.
+    # Skip it for umbrella apps since they have no build.
+    old_vsn = not Mix.Project.umbrella? && Mix.Deps.Lock.elixir_vsn
     if old_vsn && old_vsn != System.version, do: Mix.Deps.Lock.touch
 
     Enum.each Mix.Project.load_paths, &Code.prepend_path(&1)