Add warning for unrequired module

3 files changed, 42 insertions, 7 deletions

diff --git a/lib/elixir/lib/module/checker.ex b/lib/elixir/lib/module/checker.ex
index 4a49eef95..bf0877028 100644
--- a/lib/elixir/lib/module/checker.ex
+++ b/lib/elixir/lib/module/checker.ex
@@ -126,8 +126,12 @@ defmodule Module.Checker do
 
   defp check_export(module, fun, arity, meta, state) do
     case ParallelChecker.fetch_export(state.cache, module, fun, arity) do
-      {:ok, _} ->
-        check_deprecated(module, fun, arity, meta, state)
+      {:ok, :def, reason} ->
+        check_deprecated(module, fun, arity, reason, meta, state)
+
+      {:ok, :defmacro, reason} ->
+        state = warn(meta, state, {:unrequired_module, module, fun, arity})
+        check_deprecated(module, fun, arity, reason, meta, state)
 
       {:error, :module} ->
         if warn_undefined?(module, fun, arity, state) do
@@ -217,14 +221,23 @@ defmodule Module.Checker do
     ]
   end
 
-  defp format_warning({:deprecated, module, function, arity, reason}) do
+  defp format_warning({:deprecated, module, fun, arity, reason}) do
     [
-      Exception.format_mfa(module, function, arity),
+      Exception.format_mfa(module, fun, arity),
       " is deprecated. ",
       reason
     ]
   end
 
+  defp format_warning({:unrequired_module, module, fun, arity}) do
+    [
+      "you must require ",
+      inspect(module),
+      " before invoking the macro ",
+      Exception.format_mfa(module, fun, arity)
+    ]
+  end
+
   defp format_locations([location]) do
     format_location(location)
   end
diff --git a/lib/elixir/src/elixir_dispatch.erl b/lib/elixir/src/elixir_dispatch.erl
index a6cfb1b65..b15e6dddd 100644
--- a/lib/elixir/src/elixir_dispatch.erl
+++ b/lib/elixir/src/elixir_dispatch.erl
@@ -170,7 +170,7 @@ expand_require(Meta, Receiver, {Name, Arity} = Tuple, Args, E) ->
       elixir_lexical:record_remote(Receiver, Name, Arity, nil, ?line(Meta), ?key(E, lexical_tracker)),
       {ok, Receiver, expand_macro_named(Meta, Receiver, Name, Arity, Args, E)};
     true ->
-      Info = {unrequired_module, {Receiver, Name, length(Args), ?key(E, requires)}},
+      Info = {unrequired_module, {Receiver, Name, length(Args)}},
       elixir_errors:form_error(Meta, E, ?MODULE, Info);
     false ->
       error
@@ -272,7 +272,7 @@ prune_stacktrace([], _MFA, Info, _E) ->
 
 %% ERROR HANDLING
 
-format_error({unrequired_module, {Receiver, Name, Arity, _Required}}) ->
+format_error({unrequired_module, {Receiver, Name, Arity}}) ->
   Module = elixir_aliases:inspect(Receiver),
   io_lib:format("you must require ~ts before invoking the macro ~ts.~ts/~B",
     [Module, Module, Name, Arity]);
diff --git a/lib/elixir/test/elixir/module/checker_test.exs b/lib/elixir/test/elixir/module/checker_test.exs
index 7e193de12..6f645c5a7 100644
--- a/lib/elixir/test/elixir/module/checker_test.exs
+++ b/lib/elixir/test/elixir/module/checker_test.exs
@@ -402,7 +402,7 @@ defmodule Module.CheckerTest do
       assert_no_warnings(files)
     end
 
-    test "do not warn for moduel defined in local context" do
+    test "do not warn for module defined in local context" do
       files = %{
         "a.ex" => """
         defmodule A do
@@ -420,6 +420,28 @@ defmodule Module.CheckerTest do
       assert_no_warnings(files)
     end
 
+    test "warn for unrequired module" do
+      files = %{
+        "ab.ex" => """
+        defmodule A do
+          def a(), do: B.b()
+        end
+
+        defmodule B do
+          defmacro b(), do: :ok
+        end
+        """
+      }
+
+      warning = """
+      warning: you must require B before invoking the macro B.b/0
+        ab.ex:2: A.a/0
+
+      """
+
+      assert_warnings(files, warning)
+    end
+
     test "excludes no_warn_undefined" do
       files = %{
         "a.ex" => """