Do not silently discard Erlang compile errors, closes #6209

Author: José Valim

lib/mix/lib/mix/compilers/erlang.ex

@@ -42,11 +42,7 @@ defmodule Mix.Compilers.Erlang do
   of error. An error is raised at the end if any of the
   files failed to compile.
   """
-  def compile(manifest, mappings, src_ext, dest_ext, force, callback) when is_boolean(force) do
-    compile(manifest, mappings, src_ext, dest_ext, [force: force], callback)
-  end
-
-  def compile(manifest, mappings, src_ext, dest_ext, opts, callback) do
+  def compile(manifest, mappings, src_ext, dest_ext, opts, callback) when is_list(opts) do
     force = opts[:force]
     files =
       for {src, dest} <- mappings do
@@ -55,6 +51,12 @@ defmodule Mix.Compilers.Erlang do
     compile(manifest, files, src_ext, opts, callback)
   end
 
+  def compile(manifest, mappings, src_ext, dest_ext, force, callback) when is_boolean(force) do
+    IO.warn "Mix.Compilers.Erlang.compile/6 with a boolean as 5th argument is deprecated, " <>
+            "please pass [force: true]"
+    compile(manifest, mappings, src_ext, dest_ext, [force: force], callback)
+  end
+
   @doc """
   Compiles the given `mappings`.
 

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

@@ -71,7 +71,7 @@ defmodule Mix.Tasks.Compile.Erlang do
     unless is_list(erlc_options) do
       Mix.raise ":erlc_options should be a list of options, got: #{inspect(erlc_options)}"
     end
-    erlc_options = erlc_options ++ [{:outdir, compile_path}, {:i, include_path}, :report]
+    erlc_options = erlc_options ++ [:report, outdir: compile_path, i: include_path]
     erlc_options = Enum.map erlc_options, fn
       {kind, dir} when kind in [:i, :outdir] ->
         {kind, to_erl_file(dir)}
@@ -95,7 +95,14 @@ defmodule Mix.Tasks.Compile.Erlang do
         :code.delete(module)
 
         file = to_erl_file(Path.rootname(input, ".erl"))
-        :compile.file(file, erlc_options)
+        case :compile.file(file, erlc_options) do
+          {:ok, module} ->
+            {:ok, module}
+          :error ->
+            :error
+          {:error, :badarg} ->
+            Mix.raise "Compiling Erlang #{inspect file} failed with ArgumentError, probably because of invalid :erlc_options"
+        end
     end)
   end
 

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

@@ -4,11 +4,24 @@ defmodule Mix.Tasks.Compile.ErlangTest do
   use MixTest.Case
   import ExUnit.CaptureIO
 
-  setup do
+  setup config do
+    erlc_options = Map.get(config, :erlc_options, [])
+    Mix.ProjectStack.post_config erlc_options: erlc_options
     Mix.Project.push MixTest.Case.Sample
     :ok
   end
 
+  @tag erlc_options: [{:d, 'foo', 'bar'}]
+  test "raises on invalid erlc_options" do
+    in_fixture "compile_erlang", fn ->
+      assert_raise Mix.Error, ~r"failed with ArgumentError", fn ->
+        capture_io fn ->
+          Mix.Tasks.Compile.Erlang.run []
+        end
+      end
+    end
+  end
+
   test "compilation continues if one file fails to compile" do
     in_fixture "compile_erlang", fn ->
       File.write! "src/zzz.erl", """