Move mix dependencies to _build

Author: José Valim

Makefile

@@ -21,6 +21,8 @@ $(1): lib/$(1)/ebin/Elixir.$(2).beam lib/$(1)/ebin/$(1).app
 
 lib/$(1)/ebin/$(1).app: lib/$(1)/mix.exs
 	$(Q) cd lib/$(1) && ../../bin/elixir -e "Mix.Sup.start_link()" -r mix.exs -e "Mix.Task.run('compile.app')"
+	$(Q) cp lib/$(1)/_build/lib/$(1)/ebin/$(1).app lib/$(1)/ebin/$(1).app
+	$(Q) rm -rf lib/$(1)/_build
 
 lib/$(1)/ebin/Elixir.$(2).beam: $(wildcard lib/$(1)/lib/*.ex) $(wildcard lib/$(1)/lib/*/*.ex) $(wildcard lib/$(1)/lib/*/*/*.ex)
 	@ echo "==> $(1) (compile)"

lib/mix/lib/mix/cli.ex

@@ -50,9 +50,9 @@ defmodule Mix.CLI do
   defp run_task(name, args) do
     try do
       # We need to skip loading the paths for the project and
-      # its dependencies because the dependencies may be setting
-      # up or getting updated and we don't want to load their
-      # config until the process is done.
+      # its dependencies on deps.get and deps.update to avoid
+      # having two versions of the same dep after get or update
+      # is done.
       if not deps_task?(name) && Mix.Project.get do
         Mix.Task.run "loadpaths", ["--no-deps-check", "--no-elixir-version-check"]
         Mix.Task.reenable "loadpaths"

lib/mix/lib/mix/deps.ex

@@ -252,7 +252,7 @@ defmodule Mix.Deps do
     do: "the dependency requires Elixir #{req} but you are running on v#{System.version}"
 
   defp dep_status(Mix.Dep[app: app, requirement: req, opts: opts, from: from]) do
-    info = { app, req, Dict.drop(opts, [:dest, :lock, :env, :drop]) }
+    info = { app, req, Dict.drop(opts, [:dest, :lock, :env, :build]) }
     "\n  > In #{Path.relative_to_cwd(from)}:\n    #{inspect info}\n"
   end
 
@@ -341,10 +341,8 @@ defmodule Mix.Deps do
   Returns all load paths for the dependency.
   Expects a fetched dependency.
   """
-  def load_paths(Mix.Dep[manager: :mix, app: app, opts: opts]) do
-    Mix.Project.in_project(app, opts[:dest], fn _ ->
-      Mix.Project.load_paths
-    end) |> Enum.uniq
+  def load_paths(Mix.Dep[manager: :mix, opts: opts]) do
+    [Path.join(opts[:build], "ebin")]
   end
 
   def load_paths(Mix.Dep[manager: :rebar, opts: opts, extra: extra]) do

lib/mix/lib/mix/deps/converger.ex

@@ -40,11 +40,10 @@ defmodule Mix.Deps.Converger do
   an updated depedency in case some processing is done.
   """
   def all(rest, callback) do
-    config = [ deps_path: Path.expand(Mix.project[:deps_path]),
-               root_lockfile: Path.expand(Mix.project[:lockfile]) ]
+    conf = Mix.Project.deps_config
     main = Mix.Deps.Retriever.children
     apps = Enum.map(main, &(&1.app))
-    all(main, [], [], apps, config, callback, rest)
+    all(main, [], [], apps, conf, callback, rest)
   end
 
   # We traverse the tree of dependencies in a breadth-

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

@@ -40,7 +40,7 @@ defmodule Mix.Deps.Lock do
   parent project lockfile.
   """
   def lockfile do
-    Mix.project[:root_lockfile] || Mix.project[:lockfile]
+    Mix.project[:lockfile]
   end
 
   @doc """

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

@@ -79,8 +79,11 @@ defmodule Mix.Deps.Retriever do
   defp with_scm_and_app({ app, req, opts }, scms) when is_atom(app) and
       (is_binary(req) or is_regex(req) or req == nil) and is_list(opts) do
 
-    path = Path.join(Mix.project[:deps_path], app)
-    opts = Keyword.put(opts, :dest, path)
+    dest  = Path.join(Mix.Project.deps_path, app)
+    build = Path.join([Mix.Project.build_path, "lib", app])
+    opts  = opts
+            |> Keyword.put(:dest, dest)
+            |> Keyword.put(:build, build)
 
     { scm, opts } = Enum.find_value scms, { nil, [] }, fn(scm) ->
       (new = scm.accepts_options(app, opts)) && { scm, new }

lib/mix/lib/mix/project.ex

@@ -36,6 +36,8 @@ defmodule Mix.Project do
     end
   end
 
+  @private_config [:build_path, :app_path]
+
   # Invoked after each Mix.Project is compiled.
   @doc false
   def __after_compile__(env, _binary) do
@@ -46,7 +48,10 @@ defmodule Mix.Project do
   # the top of the stack can be accessed.
   @doc false
   def push(atom, file // "nofile") when is_atom(atom) do
-    config = Keyword.merge default_config, get_project_config(atom)
+    config = default_config
+             |> Keyword.merge(get_project_config(atom))
+             |> Keyword.drop(@private_config)
+
     case Mix.ProjectStack.push(atom, config, file) do
       :ok ->
         :ok
@@ -62,6 +67,14 @@ defmodule Mix.Project do
     Mix.ProjectStack.pop
   end
 
+  # The configuration that is pushed down to dependencies.
+  @doc false
+  def deps_config(config // config()) do
+    [ build_path: build_path(config),
+      deps_path: deps_path(config),
+      lockfile: Path.expand(config[:lockfile]) ]
+  end
+
   @doc """
   Retrieves the current project, `nil` if there is no
   current project (i.e. there is no mixfile in the current
@@ -93,6 +106,7 @@ defmodule Mix.Project do
 
   @doc """
   Returns the project configuration for the current environment.
+  This configuration is cached once the project is pushed into the stack.
   """
   def config do
     case Mix.ProjectStack.peek do
@@ -102,14 +116,16 @@ defmodule Mix.Project do
   end
 
   @doc """
-  Returns a list of project configuration files, for example,
-  `mix.exs` and `mix.lock`. This function is usually used
-  in compilation tasks to trigger a full recompilation
-  whenever such configuration files change.
+  Returns a list of project configuration files as known by
+  this project. This function is usually used in compilation
+  tasks to trigger a full recompilation whenever such
+  configuration files change.
+
+  By default it includes the mix.exs file and the lock manifest.
   """
   def config_files do
-    project  = get
-    opts     = [Mix.Deps.Lock.manifest]
+    project = get
+    opts    = [Mix.Deps.Lock.manifest]
 
     if project && (source = project.__info__(:compile)[:source]) do
       opts = [String.from_char_list!(source)|opts]
@@ -149,16 +165,82 @@ defmodule Mix.Project do
   end
 
   @doc """
-  Returns the paths this project compiles to,
-  collecting all `:compile_path` in case of umbrella apps.
+  Returns the path to store dependencies for this project.
+  The returned path will be expanded.
+
+  ## Examples
+
+      Mix.Project.deps_path
+      #=> "/path/to/project/deps"
+
+  """
+  def deps_path(config // config()) do
+    Path.expand config[:deps_path]
+  end
+
+  @doc """
+  Returns the build path for this project.
+  The returned path will be expanded.
+
+  ## Examples
+
+      Mix.Project.build_path
+      #=> "/path/to/project/_build"
+
+  """
+  def build_path(config // config()) do
+    config[:build_path] || Path.expand("_build")
+  end
+
+  @doc """
+  Returns the library path inside the build.
+  The returned path will be expanded.
+
+  ## Examples
+
+      Mix.Project.app_path
+      #=> "/path/to/project/_build/lib/app"
+
+  """
+  def app_path(config // config()) do
+    config[:app_path] || if app = config[:app] do
+      Path.join([build_path(config), "lib", app])
+    else
+      raise Mix.Error, message: "Cannot access build without an application name, " <>
+        "please ensure you are in a directory with a mix.exs file and it defines " <>
+        "an :app name under the project configuration"
+    end
+  end
+
+  @doc """
+  Returns the paths this project compiles to.
+  The returned path will be expanded.
+
+  ## Examples
+
+      Mix.Project.compile_path
+      #=> "/path/to/project/_build/lib/app/priv"
+
   """
   def compile_path(config // config()) do
-    unless config[:app] do
-      raise Mix.Error, message: "Cannot access compilation path without an application name, " <>
-        "please ensure you are in a directory with a mix.exs file and it defines an :app " <>
-        "name under the project configuration"
+    Path.join(app_path(config), "ebin")
+  end
+
+  @doc """
+  Builds the project structure for the current application.
+  """
+  def build_structure(config // config()) do
+    ebin = compile_path(config)
+    File.mkdir_p!(ebin)
+
+    lib = Path.dirname(ebin)
+    old = Path.expand("priv")
+
+    case :file.make_symlink(old, Path.join(lib, "priv")) do
+      :ok -> :ok
+      { :error, :eexist } -> :ok
+      { :error, _ } -> File.cp_r!(old, lib) |> IO.inspect
     end
-    Path.expand "ebin"
   end
 
   @doc """

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

@@ -63,7 +63,7 @@ defmodule Mix.Tasks.Compile.App do
       properties = ensure_correct_properties(app, properties)
       contents   = { :application, app, properties }
 
-      File.mkdir_p!(Path.dirname(target))
+      Mix.Project.build_structure(config)
       File.open!(target, [:write], &:io.fwrite(&1, "~p.", [contents]))
 
       Mix.shell.info "Generated #{app}.app"

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

@@ -245,7 +245,7 @@ defmodule Mix.Tasks.Compile.Elixir do
     end
 
     result = files_to_path(manifest, stale, to_compile, compile_path, fn ->
-      File.mkdir_p!(compile_path)
+      Mix.Project.build_structure(project)
       Code.prepend_path(compile_path)
       set_compiler_opts(project, opts, [])
     end)

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

@@ -258,7 +258,8 @@ defmodule Mix.Tasks.Compile.Erlang do
     if stale == [] && removed == [] do
       :noop
     else
-      File.mkdir_p!(Path.dirname(manifest))
+      # Build the project structure so we can write down compiled files.
+      Mix.Project.build_structure
 
       # Remove manifest entries with no source
       Enum.each(removed, &File.rm/1)