Ensure we emit a warning for recursive non used calls

Author: José Valim

lib/elixir/src/elixir_def_local.erl

@@ -14,6 +14,7 @@ macro_for(_Tuple, _All, nil) -> false;
 macro_for(Tuple, All, Module) ->
   try elixir_def:lookup_definition(Module, Tuple) of
     { { Tuple, Kind, Line, _, _, _, _ }, Clauses } when Kind == defmacro; All, Kind == defmacrop ->
+      %% This function is only called if S#elixir_scope.function /= Tuple
       elixir_import:record(Tuple, Module, Module),
       get_function(Line, Module, Clauses);
     _ ->
@@ -27,7 +28,9 @@ function_for(Module, Name, Arity) ->
   Tuple = { Name, Arity },
   case elixir_def:lookup_definition(Module, Tuple) of
     { { Tuple, _, Line, _, _, _, _ }, Clauses } ->
-      elixir_import:record(Tuple, Module, Module),
+      %% There is no need to record such calls
+      %% since they come from funtions that were
+      %% already analyzed at compilation time.
       get_function(Line, Module, Clauses);
     _ ->
       [_|T] = erlang:get_stacktrace(),

lib/elixir/src/elixir_dispatch.erl

@@ -43,7 +43,10 @@ import_function(Meta, Name, Arity, S) ->
       require_function(Meta, Receiver, Name, Arity, S);
     nomatch ->
       Module = S#elixir_scope.module,
-      elixir_import:record({ Name, Arity }, Module, Module),
+      case S#elixir_scope.function of
+        Tuple -> ok;
+        _ -> elixir_import:record(Tuple, Module, Module)
+      end,
       { { 'fun', ?line(Meta), { function, Name, Arity } }, S }
   end.
 

lib/elixir/src/elixir_translator.erl

@@ -578,8 +578,11 @@ translate_fn(Meta, Clauses, S) ->
 
 %% Locals
 
-translate_local(Meta, Name, Args, #elixir_scope{local=nil,module=Module} = S) ->
-  elixir_import:record({ Name, length(Args) }, Module, Module),
+translate_local(Meta, Name, Args, #elixir_scope{local=nil,module=Module,function=Function} = S) ->
+  case { Name, length(Args) } of
+    Function -> ok;
+    Tuple    -> elixir_import:record(Tuple, Module, Module)
+  end,
   Line = ?line(Meta),
   { TArgs, NS } = translate_args(Args, S),
   { { call, Line, { atom, Line, Name }, TArgs }, NS };

lib/elixir/test/elixir/kernel/warning_test.exs

@@ -0,0 +1,23 @@
+Code.require_file "../test_helper.exs", __DIR__
+
+defmodule Kernel.WarningTest do
+  use ExUnit.Case, async: true
+
+  import ExUnit.CaptureIO
+
+  test :invalid_token do
+    assert capture_io(fn ->
+      defmodule Sample do
+        defp hello(0), do: hello(1)
+        defp hello(1), do: :ok
+      end
+    end) =~ %r"function hello/1 is unused"
+  after
+    purge Sample
+  end
+
+  defp purge(module) do
+    :code.delete module
+    :code.purge module
+  end
+end