Load all children before parent, closes #12598

Author: josevalim

lib/mix/lib/mix/app_loader.ex

@@ -52,14 +52,13 @@ defmodule Mix.AppLoader do
   end
 
   @doc """
-  Loads the given app from path in an optimized format and returns its contents.
+  Reads the given app from path in an optimized format and returns its contents.
   """
-  def load_app(app, app_path) do
+  def read_app(app, app_path) do
     case File.read(app_path) do
       {:ok, bin} ->
         with {:ok, tokens, _} <- :erl_scan.string(String.to_charlist(bin)),
-             {:ok, {:application, ^app, properties} = app_data} <- :erl_parse.parse_term(tokens),
-             :ok <- ensure_loaded(app_data) do
+             {:ok, {:application, ^app, properties}} <- :erl_parse.parse_term(tokens) do
           {:ok, properties}
         else
           _ -> :invalid
@@ -70,11 +69,16 @@ defmodule Mix.AppLoader do
     end
   end
 
-  defp ensure_loaded(app_data) do
-    case :application.load(app_data) do
-      :ok -> :ok
-      {:error, {:already_loaded, _}} -> :ok
-      {:error, error} -> {:error, error}
+  @doc """
+  Loads the given app from path in an optimized format and returns its contents.
+  """
+  def load_app(app, app_path) do
+    with {:ok, properties} <- read_app(app, app_path) do
+      case :application.load({:application, app, properties}) do
+        :ok -> {:ok, properties}
+        {:error, {:already_loaded, _}} -> {:ok, properties}
+        {:error, _} -> :invalid
+      end
     end
   end
 

lib/mix/lib/mix/dep/converger.ex

@@ -205,10 +205,10 @@ defmodule Mix.Dep.Converger do
         all(t, [dep | acc], upper, breadths, optional, rest, lock, state)
 
       :nomatch ->
-        {%{app: app, deps: deps, opts: opts} = dep, rest, lock} =
+        {%{app: app, deps: deps, opts: opts} = dep, app_properties, rest, lock} =
           case state.cache.(dep) do
             {:loaded, cached_dep} ->
-              {cached_dep, rest, lock}
+              {cached_dep, nil, rest, lock}
 
             {:unloaded, dep, children} ->
               {dep, rest, lock} = state.callback.(put_lock(dep, lock), rest, lock)
@@ -217,7 +217,8 @@ defmodule Mix.Dep.Converger do
                 # After we invoke the callback (which may actually check out the
                 # dependency), we load the dependency including its latest info
                 # and children information.
-                {Mix.Dep.Loader.load(dep, children, state.locked?), rest, lock}
+                {dep, app_properties} = Mix.Dep.Loader.load(dep, children, state.locked?)
+                {dep, app_properties, rest, lock}
               end)
           end
 
@@ -228,11 +229,29 @@ defmodule Mix.Dep.Converger do
         {acc, optional, rest, lock} =
           all(no_longer_optional ++ t, [dep | acc], upper, breadths, optional, rest, lock, state)
 
+        # Now traverse all parent dependencies and see if we have any optional dependency.
         {discarded, deps} =
           split_non_fulfilled_optional(deps, Enum.map(acc, & &1.app), opts[:from_umbrella])
 
         new_breadths = Enum.map(deps, & &1.app) ++ breadths
-        all(deps, acc, breadths, new_breadths, discarded ++ optional, rest, lock, state)
+        res = all(deps, acc, breadths, new_breadths, discarded ++ optional, rest, lock, state)
+
+        # After we traverse all of our children, we can load ourselves.
+        # This is important in case of included application.
+        if app_properties do
+          case :application.load({:application, app, app_properties}) do
+            :ok ->
+              :ok
+
+            {:error, {:already_loaded, _}} ->
+              :ok
+
+            {:error, error} ->
+              Mix.raise("Could not start application #{inspect(app)}: #{inspect(error)}")
+          end
+        end
+
+        res
     end
   end
 

lib/mix/lib/mix/dep/loader.ex

@@ -106,7 +106,7 @@ defmodule Mix.Dep.Loader do
           {dep, []}
       end
 
-    %{validate_app(dep) | deps: attach_only_and_targets(children, opts)}
+    validate_app(%{dep | deps: attach_only_and_targets(children, opts)})
   end
 
   @doc """
@@ -383,18 +383,22 @@ defmodule Mix.Dep.Loader do
 
     cond do
       not ok?(dep) ->
-        dep
+        {dep, nil}
 
       recently_fetched?(dep) ->
-        %{dep | status: :compile}
+        {%{dep | status: :compile}, nil}
 
       opts_app == false ->
-        dep
+        {dep, nil}
 
       true ->
         path = if is_binary(opts_app), do: opts_app, else: "ebin/#{app}.app"
         path = Path.expand(path, opts[:build])
-        %{dep | status: app_status(path, app, req)}
+
+        case app_status(path, app, req) do
+          {:ok, vsn, app} -> {%{dep | status: {:ok, vsn}}, app}
+          status -> {%{dep | status: status}, nil}
+        end
     end
   end
 
@@ -411,7 +415,7 @@ defmodule Mix.Dep.Loader do
   end
 
   defp app_status(app_path, app, req) do
-    case Mix.AppLoader.load_app(app, app_path) do
+    case Mix.AppLoader.read_app(app, app_path) do
       {:ok, properties} ->
         case List.keyfind(properties, :vsn, 0) do
           {:vsn, actual} when is_list(actual) ->
@@ -446,7 +450,7 @@ defmodule Mix.Dep.Loader do
          false <- Config.Provider.valid_compile_env?(compile_env) do
       :compile
     else
-      _ -> {:ok, vsn}
+      _ -> {:ok, vsn, properties}
     end
   end
 end

lib/mix/lib/mix/dep/umbrella.ex

@@ -59,7 +59,7 @@ defmodule Mix.Dep.Umbrella do
     apps = Enum.map(deps, & &1.app)
 
     Enum.map(deps, fn umbrella_dep ->
-      umbrella_dep = Mix.Dep.Loader.load(umbrella_dep, nil, false)
+      {umbrella_dep, _} = Mix.Dep.Loader.load(umbrella_dep, nil, false)
 
       deps =
         Enum.filter(umbrella_dep.deps, fn dep ->