Wrap rebar command on windows inside escript.exe

Author: José Valim

lib/mix/lib/mix/rebar.ex

@@ -1,15 +1,36 @@
 defmodule Mix.Rebar do
   @moduledoc false
-  @local_rebar_name "rebar"
 
   # Make Mix.Rebar work like a project so we can push it into the stack.
   @doc false
   def project, do: []
 
   @doc """
-  Return the path to the local copy of rebar. Used when building deps.
+  Returns the path supposed to host the local copy of rebar.
   """
-  def local_rebar_path, do: Path.join(Mix.Utils.mix_home, @local_rebar_name)
+  def local_rebar_path, do: Path.join(Mix.Utils.mix_home, "rebar")
+
+  @doc """
+  Returns the path to the global copy of rebar, if one exists.
+  """
+  def global_rebar_cmd do
+    wrap_cmd System.find_executable("rebar")
+  end
+
+  @doc """
+  Returns the path to the local copy of rebar, if one exists.
+  """
+  def local_rebar_cmd do
+    rebar = local_rebar_path
+    wrap_cmd(if File.regular?(rebar), do: rebar)
+  end
+
+  @doc """
+  Returns the path to the rebar copy in the current working directory, if one exists.
+  """
+  def cwd_rebar_cmd do
+    wrap_cmd(if File.regular?("./rebar"), do: Path.join(File.cwd!, "rebar"))
+  end
 
   @doc """
   Loads the rebar.config and evaluates rebar.config.script if it
@@ -123,4 +144,12 @@ defmodule Mix.Rebar do
       :erl_eval.add_binding(k, v, binds)
     end)
   end
+
+  defp wrap_cmd(nil), do: nil
+  defp wrap_cmd(rebar) do
+    case :os.type do
+      { :win32, _ } -> "escript.exe #{rebar}"
+      _ -> rebar
+    end
+  end
 end

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

@@ -104,15 +104,34 @@ defmodule Mix.Tasks.Deps.Compile do
     end
   end
 
+  defp do_rebar(app, root_path) do
+    do_command app, rebar_cmd(app), "compile skip_deps=true deps_dir=#{inspect root_path}"
+  end
+
+  @rebar_cmds [:cwd_rebar_cmd, :local_rebar_cmd, :global_rebar_cmd]
+
+  defp rebar_cmd(app) do
+    Enum.find_value(@rebar_cmds, apply(Mix.Rebar, &1, [])) || handle_rebar_not_found(app)
+  end
+
+  defp handle_rebar_not_found(app) do
+    shell = Mix.shell
+    shell.info "Could not find rebar, which is needed to build #{app}"
+    shell.info "I can install a local copy which is just used by mix"
+
+    unless shell.yes?("Shall I install this local copy?") do
+      raise Mix.Error, message: "could not find rebar to compile " <>
+        "dependency #{app}, please ensure rebar is available"
+    end
+
+    Mix.Task.run "local.rebar", []
+    Mix.Rebar.local_rebar_cmd || raise Mix.Error, message: "Rebar instalation failed"
+  end
+
   defp do_command(app, command, extra // "") do
-    if System.find_executable(command) do
-      if Mix.shell.cmd("#{command} #{extra}") != 0 do
-        raise Mix.Error, message: "could not compile dependency #{app}, #{command} command failed. " <>
-          "In case you want to recompile this dependency, please run: mix deps.compile #{app}"
-      end
-    else
-      raise Mix.Error, message: "could not find executable #{command} to compile " <>
-        "dependency #{app}, please ensure #{command} is available"
+    if Mix.shell.cmd("#{command} #{extra}") != 0 do
+      raise Mix.Error, message: "could not compile dependency #{app}, #{command} command failed. " <>
+        "In case you want to recompile this dependency, please run: mix deps.compile #{app}"
     end
   end
 
@@ -127,32 +146,4 @@ defmodule Mix.Tasks.Deps.Compile do
         "In case you want to recompile this dependency, please run: mix deps.compile #{app}"
     end
   end
-
-  defp do_rebar(app, root_path) do
-    do_command app, find_rebar(app), "compile skip_deps=true deps_dir=#{inspect root_path}"
-  end
-
-  defp find_rebar(app) do
-    cond do
-      File.regular?("./rebar") ->
-        Path.join(File.cwd!, "rebar")
-
-      File.regular?(Mix.Rebar.local_rebar_path) ->
-        Mix.Rebar.local_rebar_path
-
-      System.find_executable("rebar") ->
-        "rebar"
-
-      true ->
-        shell = Mix.shell
-        shell.info "Could not find rebar, which is needed to build #{app}"
-        shell.info "I can install a local copy which is just used by mix"
-        unless shell.yes?("Shall I install this local copy?") do
-          raise Mix.Error, message: "could not find rebar to compile " <>
-            "dependency #{app}, please ensure rebar is available"
-        end
-        Mix.Task.run "local.rebar", []
-        Mix.Tasks.local_rebar_path
-    end
-  end
 end