Nuke consolidated protocols when changing Elixir versions

Author: José Valim

lib/mix/lib/mix/project.ex

@@ -353,6 +353,13 @@ defmodule Mix.Project do
     Path.join(app_path(config), "ebin")
   end
 
+  @doc """
+  The path where protocol consolidations are stored.
+  """
+  def consolidation_path(config \\ config()) do
+    Path.join(build_path(config), "consolidated")
+  end
+
   @doc """
   Compiles the given project.
 

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

@@ -41,7 +41,7 @@ defmodule Mix.Tasks.Compile.Protocols do
     Mix.Task.run "compile", args
     {opts, _, _} = OptionParser.parse(args, switches: [force: :boolean, verbose: :boolean])
 
-    output   = default_path(config)
+    output   = Mix.Project.consolidation_path(config)
     manifest = Path.join(output, @manifest)
 
     protocols_and_impls =
@@ -50,7 +50,7 @@ defmodule Mix.Tasks.Compile.Protocols do
       end
 
     cond do
-      opts[:force] || Mix.Utils.stale?(Mix.Project.config_files, [manifest]) ->
+      opts[:force] || Mix.Utils.stale?(Mix.Project.config_files(), [manifest]) ->
         clean()
         paths = consolidation_paths()
         paths
@@ -71,12 +71,7 @@ defmodule Mix.Tasks.Compile.Protocols do
   Cleans up consolidated protocols.
   """
   def clean do
-    File.rm_rf(default_path)
-  end
-
-  @doc false
-  def default_path(config \\ Mix.Project.config) do
-    Path.join(Mix.Project.build_path(config), "consolidated")
+    File.rm_rf(Mix.Project.consolidation_path)
   end
 
   defp protocols_and_impls(config) do
@@ -136,10 +131,16 @@ defmodule Mix.Tasks.Compile.Protocols do
     :code.delete(module)
   end
 
-  defp read_manifest(manifest) do
+  defp read_manifest(manifest, output) do
     case :file.consult(manifest) do
-      {:ok, [@manifest_vsn | t]} -> t
-      _ -> []
+      {:ok, [@manifest_vsn | t]} ->
+        t
+      {:ok, _} ->
+        # If manifest is out of date, remove old files
+        _ = File.rm_rf(output)
+        []
+      {:error, _} ->
+        []
     end
   end
 
@@ -156,7 +157,7 @@ defmodule Mix.Tasks.Compile.Protocols do
 
   defp diff_manifest(manifest, new_metadata, output) do
     modified = Mix.Utils.last_modified(manifest)
-    old_metadata = read_manifest(manifest)
+    old_metadata = read_manifest(manifest, output)
 
     protocols =
       for {protocol, :protocol, beam} <- new_metadata,

lib/mix/lib/mix/tasks/escript.build.ex

@@ -215,9 +215,10 @@ defmodule Mix.Tasks.Escript.Build do
     end)
   end
 
-  defp consolidated_paths(project) do
-    if project[:consolidate_protocols] do
-      Mix.Tasks.Compile.Protocols.default_path <> "/*"
+  defp consolidated_paths(config) do
+    if config[:consolidate_protocols] do
+      Mix.Project.consolidation_path(config)
+      |> Path.join("*")
       |> Path.wildcard()
       |> prepare_beam_paths()
     else

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

@@ -72,5 +72,6 @@ defmodule Mix.Tasks.Loadpaths do
 
   defp rm_rf_app(config) do
     File.rm_rf Mix.Project.app_path(config)
+    File.rm_rf Mix.Project.consolidation_path(config)
   end
 end

lib/mix/test/mix/tasks/compile.elixir_test.exs

@@ -38,19 +38,22 @@ defmodule Mix.Tasks.Compile.ElixirTest do
 
   test "recompiles project if elixir version changed" do
     in_fixture "no_mixfile", fn ->
-      Mix.Tasks.Compile.run ["--verbose"]
+      Mix.Tasks.Compile.run []
       purge [A, B]
 
-      assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
+      assert File.exists?("_build/dev/lib/sample")
+      assert File.exists?("_build/dev/consolidated")
       assert Mix.Dep.ElixirSCM.read == {:ok, System.version, Mix.SCM.Path}
 
       Mix.Task.clear
+      File.write!("_build/dev/consolidated/.to_be_removed", "")
       File.write!("_build/dev/lib/sample/.compile.elixir_scm", ~s({v1, <<"0.0.0">>, nil}.))
       File.touch!("_build/dev/lib/sample/.compile.elixir_scm", {{2010, 1, 1}, {0, 0, 0}})
 
-      Mix.Tasks.Compile.run ["--verbose"]
+      Mix.Tasks.Compile.run []
       assert Mix.Dep.ElixirSCM.read == {:ok, System.version, Mix.SCM.Path}
       assert File.stat!("_build/dev/lib/sample/.compile.elixir_scm").mtime > {{2010, 1, 1}, {0, 0, 0}}
+      refute File.exists?("_build/dev/consolidated/.to_be_removed")
     end
   end