Do not ignore unimplemented function headers from used modules

Author: josevalim

lib/elixir/src/elixir_def.erl

@@ -79,7 +79,7 @@ fetch_definition([Tuple | T], File, Module, Set, Bag, All, Private) ->
       fetch_definition(T, File, Module, Set, Bag, NewAll, NewPrivate)
   catch
     error:badarg ->
-      check_bodiless_function(Check, Meta, File, Module, Kind, Tuple),
+      elixir_errors:form_error(Meta, File, ?MODULE, {function_head, Kind, Tuple}),
       fetch_definition(T, File, Module, Set, Bag, All, Private)
   end;
 
@@ -338,12 +338,6 @@ check_valid_defaults(Meta, File, Name, Arity, Kind, 0, _, LastDefaults, true, tr
 check_valid_defaults(_Meta, _File, _Name, _Arity, _Kind, 0, _StoredDefaults, _LastDefaults, _HasBody, _LastHasBody) ->
   ok.
 
-check_bodiless_function(Check, _Meta, _File, Module, _Kind, _Tuple)
-    when Check == false; Module == 'Elixir.Module' ->
-  ok;
-check_bodiless_function(_Check, Meta, File, _Module, Kind, Tuple) ->
-  elixir_errors:form_error(Meta, File, ?MODULE, {function_head, Kind, Tuple}).
-
 check_args_for_function_head(Meta, Args, E) ->
   [begin
      elixir_errors:form_error(Meta, E, ?MODULE, invalid_args_for_function_head)

lib/elixir/test/elixir/kernel/errors_test.exs

@@ -177,6 +177,22 @@ defmodule Kernel.ErrorsTest do
                         def foo
                       end
                       '''
+
+    assert_eval_raise CompileError,
+                      "nofile:10: implementation not provided for predefined def example/2",
+                      '''
+                      defmodule Kernel.ErrorsTest.FunctionTemplate do
+                        defmacro __using__(_) do
+                          quote do
+                            def example(foo, bar \\\\ [])
+                          end
+                        end
+                      end
+
+                      defmodule Kernel.ErrorsTest.UseFunctionTemplate do
+                        use Kernel.ErrorsTest.FunctionTemplate
+                      end
+                      '''
   end
 
   test "guard without definition" do